Micro Final2 Flashcards
(500 cards)
1
Q
What common fungal infection (that is typically asymptomatic) can present with symptoms very similar to tuberculosis?
A
Cryptococcus: fever, cough, night sweats
2
Q
What organism is this? What is being used to visualize it? How does it enter the body?
A
Cryptococcus; India ink; respiratory tract
3
Q
What tissue does cryptococcus have a preference for after entering via the respiratory tract?
A
The CNS, so it causes fungal meningitis
4
Q
What is the most significant virulence factor of cryptococcus?
A
The capsule
5
Q
What is being used to visualize these budding yeast cells of cryptococcus?
A
Silver stain
6
Q
Can cryptococcus have skin manifestations?
A
Yes, it can present with a non-blanching rash or skin lesions
7
Q
How is cryptococcal infection diagnosed?
A
Visualization of organism from biopsy or CSF, or cryptococcal capsular antigen in blood or CSF
8
Q
How is cryptococcus treated?
A
Amphotericin B, 5-fluorocytosine, and fluconazole
9
Q
What organism can be spotted on this blood smear?
A
Histoplasma capsulatum, which is a fungus growing inside an RBC
10
Q
What is the vector for infection by Histoplasma capsulatum? What environments predispose somebody to this?
A
Inhalation of microconidia; spelunking or construction work, or exposure to bat guano
11
Q
A 65 y/o man entered a Mexican mine filled with bat guano, and the CT reveals these nodules. He does not have TB. What organism is most likely?
A
Histoplasmosa capsulatum
12
Q
How can histoplasmosis be diagnosed? Does having AIDS increase or decrease the sensitivity of these methods?
A
Urine histoplasma antigen, bone marrow biopsy, other biopsies, or CSF antigen; AIDS patients show increased sensitivity
13
Q
In this 50 year old AIDS patients with fever, weight loss, pancytopenia, and hemoptysis, the following organism is seen with silver stain in bronchoalveolar lavage. What is it?
A
Histoplasma
14
Q
The following organism in the liver was better visualized with silver stain on the right. It was taken from a patient from an excavation site in Ohio. What immunological structure is this? What organism is it?
A
Granuloma; Histoplasma capsulatum
15
Q
What three drugs are used to treat Histoplasma capsulatum?
A
Amphotericin, itraconazole, and voriconazole
16
Q
Where is the greatest prevalence of histoplasmosis in the US?
A
Ohio river valley
17
Q
Can serology be used to diagnose histoplasmosis?
A
Rarely
18
Q
What other dimorphic fungal infection has a prevalence pattern in the US that overlaps with Histoplasma capsulatum?
A
Blastomyces dermatitidis
19
Q
How does Blastomyces dermatitidis typically enter the body?
A
Inhalation of conidia (spores)
20
Q
What respiratory symptoms are caused by Blastomyces?
A
Atypical chronic pneumonia with mass-like lesions, lobar infilrates
21
Q
What dimorphic fungus can cause these skin manifestations?
A
Blastomyces dermatitidis
22
Q
What is the shape of the conidia of Blastomyces?
A
Ovoid
23
Q
What are two common localizations of Blastomyces infection?
A
Lungs and skin
24
Q
Where is Coccioides immitis most prevalent in the US?
A
The Southwest
25
What disease is also called San Joaquin Valley Fever?
Coccidioidomycosis, caused by *Coccidioides*
26
What is the shape of *Coccidioides* conidia?
Rectangular arthroconidia
27
What is the infectious unit of *Coccidioides*?
A barrel-shaped arthroconidium: one of these packets
28
What are the primary clinical manifestations of *Coccidioides*?
A primary pulmonary infection, usually asymptomatic, but sometimes with flu-like symptoms two weeks post exposure
29
What are risky environments for *Coccidioides* exposure?
Excavations, construction, or military exercises in the southwest US
30
What are these fungal skin lesions caused by in this patient who was at an excavation two weeks ago in the southwest US?
They are an infection of *Coccidioides*
31
How is *Coccidioides* infection treated?
Amphotericin B, and fluconazole as well in immunocompromised hosts
32
What fungus is this morphology a characteristic sign of?
It is the mariner's wheel of *Paracoccidiodes brasiliensis*
33
What is the typical worldwide origin of *Paracoccidiodes* infections?
South America
34
Do *Paracoccidiodes* infections occur equally in men and women?
No, more often in males
35
What is the route of primary infection by *Paracoccidiodes*?
Lungs
36
What are three drugs with which *Paracoccidioides* is treated?
Itraconazole, amphotericin B and TMP-SMX
37
Papular skin lesions present on this AIDS patient from Thailand. What is the most likely organism?
*Penicillum marneffei*
38
What two drugs are used to treat *Penicillum marneffei*?
Amphotericin and 5-fluorocytosine (flucytosine)
39
What fungal infection endemic in Southeast Asia produces these skin lesions? Is it common in immunocompetent hosts?
*Penicillum marneffei*; no, it is not common in the immunocompetent
40
What infection is this most likely to be, in an immunosuppressed patient from Bangladesh? What is expected to be seen on CT scan?
Mucormycosis; inflamed sinuses
41
What fungal infection is characterized by oral infections with broad ribbon-like hyphae with right angle branching?
Mucormycosis, caused by zygomycetes
42
Which is the most common fungus in the Zygomycetes family that causes oral and sinus infections, shown here?
*Rhizopus*
43
What is the hyphae pattern of *Rhizopus*?
Nonseptate ribbon-like hyphae with right angle branching
44
Why is diabetes mellitus a risk factor for mucormycosis?
Hyperglycemia and ketoacidosis causes impaired phagocytic chemotaxis
45
What fungal infection seen here can invade burn or trauma wounds and produces black necrotic lesions?
Zygomycetes, like *Rhizopus*
46
How is a zygomycete infection of a surgical wound treated?
Aggressive surgical debridement, amphotericin, and posaconazole
47
Are *Rhizopus* infections common in immunocompetent hosts?
No
48
When an opportunistic fungal infection shows septated hyphae with acute angle branching, which organism is suspected?
*Aspergillus*
49
What is an aspergilloma?
A fungus ball in the lung, walled off similar to a granuloma
50
What cell types prevent inhaled conidia of *Aspergillus* from becoming infectious in pulmonary tissue?
Macrophages and neutrophils
51
Will *Aspergillus* present in immunocompetent hosts?
Usually not
52
What is the most likely organism shown here, cultured from a heart valve in a 74 year old man with diabetes and an implanted defibrillator?
*Aspergillus* (septated acute branching hyphae)
53
What are the top three drugs used to treat *Aspergillus*?
Voriconazole, amphotericin B, caspofungin
54
What mainly determines survival in an invasive case of *Aspergillus*?
Immune recovery
55
What kind of organism is *Pneumocystis jirovecii*?
A fungus
56
What is this organism, visualized with silver stain in a lung biopsy of an AIDS patient complaining of dyspnea on exertion?
*Pneumocystic jirovecii*
57
What is the typical diagnostic test used for *Pneumocystis jirovecii*?
Direct fluorescence antibody (silver staining can also be used, but DFA is faster and more sensitive)
58
What is used to treat *Pneumocystis jirovecii*?
TMP-SMX
59
Is *Pneumocystis jirovecii* a typical infection in immunocompetent hosts?
No
60
What condition is this? What family of yeast causes it?
Athlete's foot or tinea pedis; *Trichophyton*
61
When lesions similar to athlete's foot present in the groin, what is it called?
Tinea cruris
62
What topical drugs are used to treat tinea pedis?
Miconazole and tolnaftate
63
What non-azole systemic therapy can be used against *Trichophyton rubrum* if topical antifungals fail?
Terbinafine (lamisil)
64
What is fungal onchomycosis?
Fungal infection of the nail
65
What is tinea corporis?
Ringworm
66
What organism causes ringworm?
*Trichophyton verrucosum*
67
What is the difference between a Tinea and a Taenia?
Tinea refers to cutaneous fungal infections, while taenia refers to tapeworms
68
What organism causes a superficial infection characterized by hypo or hyperpigmentation? How is it diagnosed?
*Malassezia furfur*; scrapings stained with KOH
69
What stains are used to visualize topical dermatophytes?
KOH or calcafluor white
70
Are subcutaneous fungal infections common in the US?
No, they are more typical in the tropics
71
How do the fungi in this subcutaneous infection get under the epidermis?
Local trauma and implantation
72
What subcutaneous infection of the foot will produce black fungal grains on culture?
Eumycetoma, caused by *Madurella* fungi
73
What bacterium can cause a presentation similar to eumycetoma?
Actinomycetes like *Nocardia*, which is then called actinomycetoma
74
What subcutaneous infection is commonly caused by *Madurella grisea*? What is the most typical treatment?
An infection of the foot called Madura foot; surgical removal, including possibly amputation (voriconazole and posaconazole also show some preliminary efficacy)
75
What fungal infection is associated with rose thorn punctures?
Sporotrichosis
76
What outdoor activity is a risk factor for sporotrichosis infection?
Gardening
77
What organism causes this infection associated with gardening?
*Sporothrix schenckii*
78
What is the treatment for sporotrichosis?
Sporonox (itraconazole)
79
What is the pathway of spread of *Sporothrix schenckii* after the initial subcutaneous implantation?
Lymphatic, usually up the arm
80
What fungal infection likely produced these nodules? The patient denies gardening, touching fishtanks, or construction.
*Exophiala jeanselmei*
81
What is phaeohyphomycosis? What is a potential serious target tissue of the infection?
An infection with darkly-pigmented fungi, e.g. *Exserohilum rostratum*; meningitis
82
What is this fungus, which caused an outbreak of meningitis in 2012 after a contamination of pharmaceutical goods?
*Exserohilum rostratum*
83
What are three typically targeted cellular processes by antifungals?
The cell membrane which uses ergosterol instead of cholesterol, DNA synthesis, and the cell wall
84
What is the mechanism of fluconazole?
It inhibits ergosterol synthesis
85
What is the suffix used for drugs that inhibit ergosterol synthesis?
#NAME?
86
What cellular process is targeted by flucytosine?
DNA synthesis
87
How do polyene antibiotics kill fungi?
They cause direct membrane damage
88
What part of the cell is attacked by the antifungal amphotericin?
The cell membrane
89
What drug is this? What is its mechanism?
Amphotericin; disruption of the fungal cell membrane
90
Is oral ketoconazole still typically used?
No
91
What are the two first generation triazoles?
Itraconazole and fluconazole
92
What are the two second generation triazoles?
Voriconazole and posaconazole
93
What kind of enzyme is responsible for converting lanosterol to ergosterol in fungi? What class of drugs inhibits it?
A cytochrome P450; azoles
94
Do azoles cross-react with mammalian cytochrome p450s?
Some cross-reactivity is seen
95
Is fluconazole fungicidal or fungistatic?
Fungistatic
96
Does fluconazole have an oral formulation? Is it narrow or broad spectrum?
Yes, there is an oral formulation; it is narrow spectrum
97
What organisms is fluconazole very effective against?
*C. albicans* and *Cryptococcus*
98
Do non-*albicans* *Candida *species respond to fluconazole?
Usually, no
99
What are common adverse effects of fluconazole?
Nausea, vomiting, rash
100
What sort of drugs have bad interactions with fluconazole, e.g., what tissue are those drugs metabolized by?
Drugs that are metabolized by or inhibit liver enzymes
101
Is itraconazole more or less orally bioavailable than fluconazole?
Less
102
Which azole is cleared renally instead of by the liver?
Fluconazole
103
Which triazole antifungal has the shortest serum half life?
Voriconazole
104
What is the advantage of second generation triazoles?
They are more broad spectum, e.g. include all *Candida* species, Aspergillus, Fusarium
105
Which triazole is not effective against *Aspergillus*?
Fluconazole
106
Which triazole has poor CSF penetration?
Itraconazole
107
What is a unique adverse effect of voriconazole compared to other triazoles?
Visual disturbances
108
What azole is used for invasive histoplasma, blastomycosis, and sporotrichosis?
Itraconazole
109
For invasive aspergillosis, what triazole is preferred?
Voriconazole
110
What triazole is preferred for mucormycosis?
Posaconazole
111
Which triazole uniquely produces osmotic diarrhea at high doses?
Itraconazole
112
What drug would be preferred to treat this fungal infection of the oral cavity and sinuses?
Posaconazole (the infection is mucormycosis caused by zygomycetes)
113
Does posaconazole have an oral formulation, an IV formulation, or both?
Only an oral formulation
114
What is the mechanism of terbinafine?
Interferes with ergosterol synthesis
115
What is terbinafine used to treat?
Superficial fungal infections, e.g. onychomycosis
116
What topical therapy can be used against oral thrush? What is its benefit?
Nystatin; it has little toxicity and is not absorbed by the body
117
What infections may be treated with clotrimazole?
Mucocutaneous candidiasis and dermatophyte infections (e.g. ringworm)
118
What is the meaning of "polyene macrolide"?
It has many double bonds (polyene) and a ring with more than 12 atoms (macrolide)
119
What drug is shown here and what is it doing?
Amphotericin B, forming a pore in a cell membrane to kill a fungus
120
What is the most significant delayed toxicity of amphotericin B?
Nephrotoxicity
121
What is amphotericin B the drug of choice for?
Cryptococcal meningitis, mucormycosis, histoplasmosis, and invasive fungal infection that does not respond to other therapy
122
What is flucytosine most commonly used to treat in the US?
Cryptococcal meningitis
123
What class of drugs does caspofungin belong to? What part of the fungus does it target?
Echinocandins; the cell wall
124
What three genuses of fungi are echinocandins very active against?
All *Candida* species, *Pneumocystis jirovecii*, and most *Aspergilllus* species
125
Do echinocandins have activity against systemic dimorphic endemic fungi, e.g. *Coccidioides*?
Not really, so they usually can only be used in conjunction with other drugs
126
Can caspofungin be given orally?
No
127
What are typical adverse effects of caspofungin infusion?
Intravenous site irritation, infusion related adverse effects consistent with histamine release
128
What are the two most common organisms causing fungal endophthalmitis?
*C. albicans* and *Aspergillus*
129
What is used to treat fungal endopthalmitis?
Intravitreal administration of amphotericin
130
What other fungal skin lesions are those caused by *Penicillum marneffei* difficult to distinguish from?
Cryptococcal lesions
131
What is another (more generic) name for the drug Sporonox?
Itraconazole
132
Are human parasites eukaryotes or prokaryotes? Can they be multicellular, unicellular, or both?
Eukaryotes; they can be both multicellular and unicellular
133
What are the two general classes of helminths?
Nematodes and platyhelminthes
134
What are the unicellular parasites classified as?
Protozoa
135
What are the presenting symptoms of malaria?
Fever, shivering, pain in the joints, headache, and vomiting
136
Approximately how many cases of malaria occur per year worldwide?
~200 million
137
Where do most cases of malaria occur today?
90% are in Africa
138
What parasite is visualized in these RBCs? It is found in a 45 year old UN employee.
*Plasmodia falciparum*, identifiable by the multiply infected red cells and heavy parasitemia
139
Which *Plasmodium* causes the worst type of malaria?
*P. falciparum*
140
Which mosquito transmits *P. falciparum*?
Anopheles mosquito
141
What are these called? What organism are they characteristic of?
Schizonts; *Plasmodium ovale,* since the RBC is enlarged and oval
142
What additional treatment is required against *P. ovale and P. vivax*?
Primaquine
143
What cell type within mosquitos is colonized by *Plasmodium*?
Gametes, which become oocysts
144
What tissue is the first area of replication for *Plasmodium* entering a human host?
The liver
145
Why is it possible for malaria to manifest months to years after exposure?
The parasite can spend a long time replicating in the liver before being released into the bloodstream
146
What is the structure indicated with a white arrow, known as the resting stage of *Plasmodium*?
A hypnozoite
147
What is the basis of the malaria rapid diagnosis test?
Antibodies that bind to malaria antigens in the blood
148
What is the second most lethal cause of malaria?
*Plasmodium vivax*
149
What are most *P. falciparum* strains now resistant to which complicates treatment?
Chloroquine
150
How are hypnozoites significant to the prognosis of a malaria case? Which species of malaria does not have them?
Being a latent form of the parasite, they can cause a relapse after a round of treatment; *Plasmodium falciparum* does not have them so it will not relapse after a successful treatment with RBC schizonticides
151
What is the most feared complication of *P. falciparum* infection? What are the symptoms?
Cerebral malaria; seizure, altered mental status, and hypoglycemia
152
What are these? Which *Plasmodium* are they helpful in identifying?
Banana-shaped gametocytes; *P. falciparum*
153
Are schizonts seen in peripheral blood smears of a patient with *P. falciparum*?
Usually not
154
What is this structure that merozoites like *Plasmodium* use to enter the red blood cell?
The parasitopherous vacuole
155
Why can cerebral malaria cause ischemia of the brain?
Parasitized RBCs attach to endothelial cells and sequester in cerebral capillaries, because of the knobs shown on this EM
156
What is visualized in pathological examination of cerebral malaria?
Ring hemorrhages
157
What is the pigment that is deposited in tissue following malaria infection?
Hemozoin
158
Why is primaquine necessary for treatment of *P. vivax* and *P. ovale*?
It acts against hypnozoites, a dormant form of the parasite, which would otherwise cause relapse of the malaria after months or years
159
Which malaria parasite is seen here?
*P. vivax*, due to the prevalence of schizonts (and they are not oval shaped as in *P. ovale* although the distinction is minute)
160
Which two *Plasmodium* species may be hard to differentiate on peripheral blood smear?
*P. ovale *and *P. vivax*
161
What kind of drug is primaquine? What tissue does it primarily act upon to kill *Plasmodium*?
Tissue schizontocide; liver
162
Is primaquine effective against the erythrocytic forms of *Plasmodium*?
No, so a chloroquine is required as well
163
When is primaquine contraindicated?
In the case of a G6PD deficiency, which would cause hemolytic anemia
164
What human diseases are also protective against malaria?
Sickle cell disease and thalassemia
165
Does *Plasmodium malariae *have a hypnozoite form? How long can the organism persist in blood after the initial infection?
No; for 20-30 years
166
Does *P. malariae* present with schizonts in the peripheral blood smear? What is particularly distinguishable about its blood smear appearance?
Yes, there are schizonts; there are also band forms of infected RBC's
167
Is quinine still effective against all four species of *Plasmodium*? Is it available as an IV formulation?
Yes; No, instead IV quinidine is used
168
What herbal remedy based on "Chinese wormwood" was recently approved as a powerful antimalarial?
Artemesinin
169
What was the most important component of malaria control efforts in the early 20th century?
Eliminating breeding sites for the mosquito vector
170
What is this parasite, transmitted by the same ticks that carry *Anaplasma* and *Borellia* *burgdorferi*?
*Babesia microti*
171
What is the animal reservoir (not the vector) of *Babesia*?
White footed mice and small rodents
172
What drugs are used to treat *Babesia*?
Atovaquone and azithromycin
173
Where are most cases of babesia in the United States from?
Coastal vacation areas with more ticks, e.g. eastern LI, Shelter Island
174
What are the clinical manifestations of babesiosis in an immunocompetent host?
Mild flu-like illness after 1-6 weeks, including malaise/fatigue/fever, chills and sweats
175
Do most patients with babesiosis recall a tick bite?
No
176
How could a bedbound 85 year old man with hemolytic anemia in East Harlem get babesia?
Blood transfusions are a vector for parasite transmission
177
Which species of nematode parasites are generally the largest?
*Ascaris lumbricoides*
178
How many people in the world are infected with Asc*aris lumbricoides*? Although many are asymptomatic, what is a clinical presentation usually a result of?
25%; obstruction of the intestine
179
Are children more or less at risk to develop complications from infection by *Ascaris lumbricoides*?
More, because their intestine is smaller and more prone to blockage
180
How does *Ascaris lumbricoides* stay in the upper GI tract? How many eggs are produced daily?
They do not attach to the wall, but instead contract their muscles against the fecal stream and peristalsis; about 2000 eggs/day
181
What life stage of *Ascaris lumbricoides* can penetrate the intestinal wall to enter the bloodstream? What tissues are then affected?
Larvae; they move through the liver and then into the right heart and lungs, and then are coughed up and re-ingested, at which point they are young adults and resistant to gastric acidity
182
What are the two clinical manifestations of *Ascaris lumbricoides*?
Intestinal obstruction and nutrient impairment
183
What are the two most commonly used drugs for treating nematode infections?
Albendazole and mebendazole
184
What is the mechanism of benzimidazoles? What are two used in mass treatment campaigns?
They inhibit the assembly of microtubules and uptake of glucose by helminths; albendazole and mebendazole
185
What can be used to treat the nematodes *Ascaris lumbricoides, Necatur americanus, Ancylostoma duodenale, Strongyloides, Enterobius,* and *Trichuris*?
Benzimidazoles
186
What is the common suffix for benzimidazoles? What are they used to treat?
-bendazole, e.g. Albendazole; nematode parasites
187
How is *Ascaris* transmitted between humans?
Ingestion of eggs from fecally contaminated soil or food
188
What is the difference between the methods of *Necatur americanus* and of *Ascaris lumbricoides* in staying within the small bowel?
*Necatur* attaches to the intestinal with small teeth, while *Ascaris* swims upstream. *Necatur's* mouth is pictured:
189
What is the layman name for *Necatur americanus* and *Ancylostoma duodenale*?
Hookworm
190
How long can adult hookworms be?
9mm-13mm
191
What is the typical clinical presentation of a patient with hookworm?
Childhood anemia
192
How does hookworm enter the body?
It penetrates the skin such as the bare foot, or can enter via the pulmonary or digestive tracts
193
What is this condition called, caused by a zoonotic parasite that is moving around the surface of the foot?
Cutaneous larva migrans
194
What is cutaneous larva migrans?
A migrating rash caused by a zoonotic parasite under the skin
195
Why do parasites involved in cutaneous larva migrans stay under the skin and not enter the bloodstream?
They are zoonotic and cannot complete their lifecycle in a human host, so they wander around the dermis layer leaving itchy tracks
196
What is the name of the dog hookworm? What condition does it cause?
*Ancylostoma braziliense*; Cutaneous larva migrans, a creeping eruption caused by worms under the skin
197
Where are zoonotic hookworms common in the US?
Southeastern US and tropical areas
198
How are zoonotic (e.g. dog) hookworms treated?
Ivermectin or albendazole
199
How is a case of human hookworm infection diagnosed? How is it treated?
Visualization of eggs in the stool; mebendazole or albendazole
200
Why are there tracks of bacteria in this streaked sputum culture of a patient with dyspnea and wheezing from Peru?
Because of *Strongyloides*, a nematode leaving tracks of bacteria as it moves around the plate
201
How does *Strongyloides* enter the body? Where does it* *replicate? How does it get there?
It penetrates the skin as a larval form; it replicates in the small intestine; the larvae migrate from the skin to the circulation to the lungs, where they are coughed and reingested, entering the GI tract
202
How is *Strongyloides* diagnosed?
Visualization of larvae or eggs in the stool
203
How may *Strongyloides* enter a patient with a PMH of GI issues that has never traveled to places where this parasite is endemic?
Small bowel transplant from somebody who had the parasite
204
Where is *Strongyloides* endemic?
Southeastern US and the tropics
205
What is the most serious manifestation of *Strongyloides* infection? What is the major risk factor for this presentation as opposed to other less serious presentations?
Hyperinfection syndrome; being immunocompromised
206
How is *Strongyloides* treated?
Ivermectin, thiabendazole or albendazole
207
Which three intestinal nematodes have a life cycle that passes through the lungs? What is similar about the method of entry of these nematodes?
The hookworms *Necatur americanus* and *Ancylostoma duodenale* and the worm *Strongyloides stercoralis*; they all enter the body by penetrating skin
208
What are these tiny ovoid structures inside this nematode?
Eggs
209
Where is pinworm prevalent throughout the US?
The entire country
210
What are symptoms of pinworm infection?
Perianal itching or vaginitis
211
What is the scientific name for pinworm?
*Enterobius vermicularis*
212
What is the most common intestinal nematode infection in the US?
Pinworm (*Enterobius vermicularis*)
213
What are risk factors for pinworm infection?
Humidity, crowding, and a high proportion of school age children
214
What is this organism that is migrating to the perianal region to lay eggs and is prevalent throughout the US?
Pinworm (*E. vermicularis*)
215
What is the method of transmission for *Enterobius vermicularis*?
Fecal-oral
216
What is the "Scotch Tape" test? What parasite is it used to diagnose?
Tape is applied to the perianal area and examined microscopically for ova; this will detect pinworm (*Enterobius vermicularis*)
217
How is pinworm treated?
Mebendazole, albendazole, or pyrantel pamoate
218
If albendazole and mebendazole are not available, what else can be used to treat pinworm? What is its mechanism of action?
Pyrantel pamoate; it is a neuromuscular junction blocker that paralyzes them
219
What organism are these eggs from? What telltale feature is used to identify them?
Whipworm (*Trichuris trichiura*); the polar plugs
220
What parts of the world are endemic for *Trichuris trichiura* infection?
Warm moist climates, so SE Asia, sub-Saharan Africa, and the Caribbean
221
Does *Trichuris trichuria* pass through the human lungs in its life cycle?
No
222
What organism is this? What is a severe complication of infection that is preceded by tenesmus?
Whipworm (*Truichuris trichiura*); rectal prolapse
223
How is *Trichuris trichiura* transmitted?
Fecal-oral (ingestion of eggs in stool)
224
How is whipworm (*Trichuris trichiura*) treated?
Mebendazole or albendazole
225
What nematode infection causes elephantiasis of the limbs? What is the mechanism for this? Does the elephantiasis subside after the parasite is killed?
Filariasis; lymphedema due to lymphatic blockage by the parasite; no, the damage to the lymphatics is permanent
226
What is the vector for infection by parasites that cause filariasis? What parts of the world are still endemic for it?
Mosquitos; tropical regions
227
When is a blood sample to diagnose filariasis taken? Why?
During the night time; because the adult worms release microfilariae at the time of mosquito feeding
228
What condition is this, caused by the parasite on the right?
Lymphatic filariasis, caused by a variety of nematodes, most significantly *Wuchereria bancrofti* and *Brugia* species
229
What manifestation of infection is produced by *Onchocerca volvulus*? How is it transmitted between humans;
River blindness, caused by the organism migrating to the eye; subcutaneous infection by blackfly bites
230
What disease is caused by *Wuchereria bancrofti*?
Lymphatic filariasis, which produces elephantiasis of limbs
231
Where is *Onchocerca volvulus* endemic?
Africa, Latin America, and the Middle East
232
How is *Dracunculis medinensis* transmitted? How can an endemic community prevent this?
Drinking water contaminated with larvae; filtering the water through a nylon mesh
233
What extraocular symptoms associate with river blindness? How long can these symptoms persist without treatment?
Subcutaneous nodules and dermatitis where the microfilariae are being produced by adult females under the skin; 9 years
234
How long does it take for the guinea worm to produce a blister on the skin? How does the worm get from the site of infection to the skin?
About 1 year; it penetrates the stomach and intestinal wall, and travels via the abdominal cavity and retroperitoneal space toward the skin
235
What is the scientific name for the guinea worm?
*Dracunculis medinsis*
236
How is an infection by *Dracunculis medinsis* treated?
Mechanical extraction of the worms from the skin, and topical treatment with antibiotics if superinfection is suspected (no antihelminthics are available)
237
When does the *Dracunculis medinsis* female release eggs from a skin lesion?
When the lesion is brought into contact with water, which the patient usually does to relieve the local discomfort
238
What is the structure of a cestode?
They are flat ribbonlike worms. The head or scolex is followed by an elongating chain of proglottids, segments that comprise independent reproductive units
239
How long can cestodes become?
Up to 12m
240
What kind of a worm is this?
A cestode or "tapeworm"
241
What is the reservoir for tapeworm? How is tapeworm transmitted to humans?
It lives in the muscles of livestock or fish; humans are infected by ingesting raw or undercooked infected meat
242
What is the scientific name for the fish tapeworm?
*Diphyllobothrium latum*
243
What is the typical treatment for flatworms?
Praziquantel
244
What is the morphological difference between the scolex of the beef and the fish tapeworm?
The fish tapeworm (*Diphylobothrium latum*) has hooks on its scolex, while the beef tapeworm (*Taenia saginata*) has no hooks on its scolex
245
Does the pork tapeworm have a scolex with hooklets? What is its scientific name?
Yes;* Taenia solium*
246
What countries would rarely harbor *Taenia solium* infections?
Muslim countries
247
What is the number one cause of adult-onset seizures in the developing world?
Parasitic infection
248
What is a tapeworm infection of the brain called?
Neurocysticercosis
249
What parasitic infection of the brain is seen here?
Neurocysticercosis (tapeworm)
250
What organism causes neurocysticercosis?
*Taenia solium* (pork tapeworm)
251
How is *Taenia solium* infection of the brain ventricles treated?
Surgical removal is indicated if the infection is within the ventricles
252
When is albendazole indicated for neurocysticercosis?
For 5-100 lesions and when the ventricles are not involved
253
What is the mechanism of praziquantel?
It damages the worm integument and allows for Ca++ influx
254
What organism causes a hydatid cyst?
*Echinococcus granulosus,* the dog tapeworm
255
What organism is the reason for sandbox covers? How does it enter the body?
*Echinococcus granulosus*, the dog tapeworm; ingesting eggs from dog feces
256
What organism is associated with a salty taste in the mouth while coughing?
Dog tapeworm (*Echninococcus granulosus*) which creates hydatid cysts that rupture and spill scolices that taste salty
257
What treatment is used to remove *Echinococcus granulosus*? What animal(s) harbor this tapeworm?
Surgical excisions, like the PAIR procedure, or albendazole when this is not possible; Dog and sheep
258
What differentiates the progression of intestinal infection as opposed to neurocysticercosis in the event of *Taelia solium* exposure?
Whether it was in undercooked pork (which causes GI manifestation) or in food contaminated by feces of an infected human (neurocysticercosis course)
259
What parasites are shared between snails and humans? Are they segmented like tapeworms?
Trematodes (flukes); no
260
What structure is seen on the egg of a trematode?
A lid-like structure called an operculum
261
What determines the different manifestations of splenomegaly, hepatomegaly, hematuria, or CNS involvement for cases of schistosomiasis?
The particular species of trematode involved, which differs based on the location of the exposure
262
What is the major strategy for preventing outbreaks of schistosomiasis?
Preventing contamination of the water supply by snails, which harbor the sporocysts
263
How do trematodes enter the body in the course of causing schistosomiasis? Where in the body do they mature?
They penetrate the skin upon exposure to water containing cercariae released by infected snails; they mature in the liver
264
How do trematodes return from humans to their animal reservoir (freshwater snails)?
Excretion of eggs in feces and urine
265
What kind of immune response is generated in response to trematode eggs during schistosomiasis?
A Th2 response
266
What are the four clinically relevent species of *Schistosoma*? How are they all treated?
*S. mansoni, S. hematobium, S. japonicum, S. mekongi*; Praziquantel
267
What led to an outbreak in hepatitis C near the Aswan dam in Egypt?
Tartar emetic was administered to prevent schistosomiasis because of the increase in freshwater snails, but many syringes were reused, spreading HCV
268
What is the common name of *Opistorchis sinensis*? How does it enter a human host? What cancer does it increase the risk of?
Chinese liver fluke; ingestion of raw freshwater fish; Bile duct cancer
269
How can humans be infected with *Fasciola hepatica*? Where does it reside in humans?
Ingestion of raw watercress; in the bile ducts
270
What is the common name of *Fasciola hepatica*? How is it treated?
Liver fluke; triclabendazole
271
What is the only trematode *not* treated with praziquantel? What is it treated with?
Liver fluke (*Fasciola hepatica*); triclabendazole
272
What is the pathogenetic mechanism of most forms of schistosomiasis?
Inflammatory reaction to the eggs
273
What parasites must spend part of their lifecycle in a snail?
Trematodes
274
What are the two most likely intestinal protozoa to present in the US?
*Entamoeba histolytica *and *Giardia lamblia*
275
What is the primary reservoir for *Entamoeba histolytica*? What organ(s) does it attack?
Humans; the liver, lungs, the GI wall, and in rare cases, the brain. Large cysts are formed:
276
What organism causes the majority of amebiasis cases in developing countries?
*Entamoeba histolytica*
277
How is *Entamoeba histolytica* transmitted?
Fecal-oral
278
What type of colitis is this? What organism is likely responsible?
Amebic colitis; *Entamoeba*
279
In what extraintestinal tissues can *Entamoeba* form abscesses?
Liver, lungs, and brain
280
What is a condition caused by *Entamoeba *that manifests as stool with blood mucous and pus (that may have been the cause of Thomas Jefferson's death)?
Amebic dysentery
281
How is *Entamoeba* treated?
Metronidazole (or tinidazole)
282
What is the amoeba that causes infection via direct inoculation into nares, pictured here causing a fatal infection of the brain?
*Balamuthia*
283
What is the prognosis for infection by free living amoeba?
Almost invariably, death
284
What kind of organisms are *Acanthamoeba*, *Balamuthia*, and *Naegleria*? Do they spread host-to-host or through the enviroment?
Free-living amoeba; they can spread in the environment as a trophozoite or cyst form
285
What dramatic infection seen here is caused by a contamination of contact lens solution?
Acanthamoeba keratitis
286
What form of *Giardia lamblia *is seen on the right side of this picture that is capable of surviving in the environment?
The cyst form
287
What kind of symptoms are produced by *Giardia lamblia*?
GI symptoms: nausea, diarrhea, fatigue and weight loss
288
How many *Giardia* cysts are necessary to cause in infection via ingestion?
Only 10
289
What triggers the transformation from the cyst form back into the trophozoite form for *Giardia* entering the body?
The gastric acid exposure in the stomach
290
Why does* Giardia* cause malabsorption and lactase deficiency?
It inhibits several digestive enzymes and absorbs nutrients from the host's GI tract, while also causing loss of the intestinal brush border
291
What infectious organism is this, present on an intestinal wall and causing chronic diarrhea and malabsorption even after successful treatment?
*Giardia*
292
How is *Giardia lamblia* infection treated?
Tinidazole or metronidazole
293
How is *Giardia lamblia* transmitted?
Fecal-oral
294
How is *Trichomonas vaginalis* transmitted?
Sexual contact
295
Do males develop symptoms of *Trichomonas vaginalis*?
Usually no
296
What sexually transmitted protozoan commonly causes vaginitis and cervicitis, with no cyst form or mitochondria?
*Trichomonas vaginalis*
297
What are these curious little spiral organisms that cause fever, myalgias, orbital edema, and eosinophilia? How are they transmitted to humans?
*Trichinella spiralis*; eating undercooked meat
298
What tissue do *Trichinella spiralis* organisms enter to cause a brisk inflammatory response (fever, myalgias)? How do they get there from the GI tract?
Muscle; penetration of the bowel wall and entering circulation
Here is the organism in muscle:
299
What form of *Cryptosporidium* is ingested to cause the infection?
The cyst form
300
How is *Cryptosporidium *diagnosed?
Visualization of parasites with acid fast or an immunostain of the stool sample
301
What properties do *Cryptosporidium, Isospora, Cyclospora*, and *Microsporidium *share in common?
They are all intestinal spore-forming protozoa
302
What spore-forming protozoa caused an outbreak affecting \>400k people in Milwaukee in 1993? What caused it?
*Cryptosporidium*; contamination of the water supply
303
In AIDS patients, what does *Cryptosporidium* manifest as?
Wasting syndrome (HIV-related cachexia)
304
Is *Cryptosporidium* larger or smaller than other spore-forming protozoans?
Smaller than most, hence the name *Cryptosporidium _parvum_ *meaning "small"
305
What nucleated, single-celled obligate intracellular protozoan without mitochondria presents as an opportunistic infection in AIDS patients and immunosuppressed patients?
*Microsporidium*
306
What is the treatment for *Microsporidia* and *Cryptosporidia*?
Since they are usually symptomatic in immunocompromised patients, the immune system is reconstituted, e.g. with antiretrovirals in AIDS patients to bring up the CD4+ count
307
In Africa, what insect transmits sleeping sickness, also called African trypanosomiasis?
The Tsetse fly
308
What organism causes Chagas disease in South America?
*Trypanosoma cruzi*
309
What parasite pictured here is transmitted by the sandfly?
The *Leishmania* species
310
What are the sympotoms of cutaneous leishmaniasis?
Clusters of skin lesions and palpable subcutaneous nodules (the lymph nodes)
311
What are these skin lesions and this slide of skin scrapings indicative of?
Leishmaniasis
312
What organism is the vector Leishmaniasis?
The sandfly
313
What organism is the vector for Chagas disease, also called South American trypanosomiasis?
The kissing or Riduviid bug
314
Where is Leishmaniasis endemic?
Many countries in the New and Old Worlds, including Central and South America, Europe, Asia, and the Middle East
315
Besides cutaneous leishmaniasis, how else can the parasite manifest clinically?
Mucocutaneous or visceral symptoms
316
What tissues are targeted in mucocutaneous leishmaniasis?
The nose, oropharynx and larynx
317
What two drugs are used to treat Leishmaniasis?
Pentavalent antimonials (heavy metals) or amphotericin B
318
What compound has demonstrated preliminary efficacy against New World cutaneous Leishmaniasis but is not yet FDA approved?
Miltefosine
319
What species causes the diseases called Dum Dum fever or Kala Azar?
*Leishmania* species
320
What fungi mimics the histologic appearance of *Leishmania*?
*Histoplasma capsulatum*
321
What are the animal reservoirs for Leishmaniasis?
Rodents and canines
322
What are the three categories of manifestations of Leishmaniasis?
Cutaneous, mucocutaneous, and visceral
323
What protozoan parasite can be seen here, which is distributed by the Chinch bug?
*Trypanosoma cruzi*
324
How far north is the distribution of the Chinch (Chagas) bug that causes South American trypanasomiasis?
As far north as Mexico
325
Does *T. cruzi* enter the body via oral secretions of the chinch bug?
No, the trypomastigotes enter from feces secreted by the chinch bug and travel into the bite wound or a mucosal membrane
326
The acute phase of what Central and South American parasitic infection is seen here? What is this sign called?
*Trypanosoma cruzi*; Romana's sign or chagoma
327
What three organs are enlarged in the chronic progression of South American trypanosomiasis?
The heart, esophagus, and colon
328
Do trypomastigotes replicate in the blood in African, South American, or both localizations of trypanosomiasis?
Only African
329
What are the two treatments of choice for acute Chagas disease? What is their mechanism?
Benznidazole or nifurtimox; they form oxygen radicals within the parasite
330
How is Chagas disease diagnosed?
Peripheral blood smear showing trypomastigotes or xenodiagnosis and culture (of the offending insect vector, the Riduviid bug)
331
What organisms cause African sleeping sickness?
*Trypanosoma brucei gambiense* and *Trypanosoma brucei rhodesiense*
332
What is the prognosis of untreated African sleeping sickness?
Death
333
How does *Trypanosoma brucei* evade the immune system?
It alters its antigenic surface proteins if it is discovered by white blood cells
334
How does African trypanosomiasis kill its host?
It enters the CNS and performs irreversible damage to the brain
335
What is the first sign of infection with African sleeping sickness? What is its name?
Extracellular proliferation of parasites at the site of the Tsetse fly bite(s); Winterbottom's sign
336
How long does it take for African sleeping sickness to progress to the CNS stage?
Months to years
337
What causes the daytime somnolence of African trypanosomiasis?
Disruption of normal circadian rhythms
338
Is Toxoplasmosis rare or relatively common in the US?
It is relatively common but typically asymptomatic
339
If *Toxoplasma gondii* does cause symptoms in an immunocompetent host, what are they typically?
Mononucleosis-type illness and lymphadenopathy
340
Can a congenital infection of toxoplasmosis have severe effects on the neonate?
It is rare, but yes there can be severe effects, including mental retardation, hydrocephalus, and blindness
341
In immunocompromised or immunosuppressed hosts, what can *Toxoplasma gondii* infections manifest as?
Encephalitis and pneumonia
342
What organism is this, which is transmitted by eggs glued to a mosquito which drop during feeding and burrow into the skin of the host?
The botfly, *Dermatobia hominis*
343
What is the major determinant of the risk of infection by opportunistic pathogens (that can be measured via blood tests)?
CD4 count
344
What type of infections would defects in cell mediated immunity increase risk for? What about defects in neutrophils?
Cell-mediated: viral pathogens; Neutrophils: bacteria and fungi
345
How can the severity of immunosuppression in a transplant be quantified?
The dose and type of immunosuppressents and the recency of rejections or graft-versus-host disease
346
What is typically the only effective therapy for eliminating opportunistic pathogens in an immunocompromised patient and hence the primary objective?
Restoring immune function
347
How can immune function be restored in a neutropenic patient that is experiencing an opportunistic infection?
Granulocyte colony stimulating factor (GCSF) or other growth factors
348
What are the first typical opportunistic pathogens to appear in an AIDS patient once the CD4 count drops below 500/μL?
Bacterial pneumonia or pulmonary TB, mucocutaneous candidasis, shingles, oral hairy leukoplakia, and Kaposi's sarcoma
349
Does chronic herpes simplex infection typically begin to appear in AIDS patients with lower or higher CD4 counts than those that present with oral hairy leukoplakia?
Lower
350
What are the final opportunistic pathogens that attack AIDS patients when their CD4 count drops below 50/μL?
Disseminated *Mycobacterium avium* and cytomegalovirus
351
An AIDS patient presenting with hypoxemia and this CXR is likely experiencing what opportunistic infection, particularly if he responds to TMP/SMX? Is a DFA for this organism in sputum always sufficiently sensitive?
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*Pneumocystic jirovecii* pneumonia; no, the DFA may not be sensitive enough with sputum
352
What opportunistic pathogen are all of these lab detection methods being used to identify?
*Pneumocystic jirovecii*
353
What staining can be used to detect *Mycobacterium avium*? What must be noted about the culture requirements for this organism?
Acid fast; culture requires a special medium and may take weeks
354
What disease symptoms are caused by *Mycobacterium avium* in AIDS patients?
A disseminated disease called MAC that causes fevers, chills, sweats, weight loss, and diarrhea, with infection of many organs
355
What is this infection, common in AIDS patients, that presents with ring-enhancing lesions in the brain after fever and headache for a week?
Toxoplasmosis
356
A 35 year old man with AIDS presents with fever and headache for a week and has no ring enhancing lesions in the brain, but instead an India ink stain of CSF reveals the following. What organism is this? What treatment is recommended?
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*Cryptococcus neoformans*; amphotericin B and flucytosine
357
What viral infection is common in AIDS patients that causes weakness of the extremities, and patchy T2 hyperintensities without enhancement near the gray-white junction in a brain MRI?
JC (John Cunningham) virus
358
What is the genomic makeup of JC virus? Does it have an envelope?
Double-stranded DNA virus; no envelope
359
Does JC virus normally cause disease in immunocompetent individuals?
No
360
How does JC virus enter the body? Where does it create a latent infection?
Enters via respiratory tract; latent infection of kidney
361
Why does JC cause weakness of the extremities?
Reactivation of the virus can lead to viremia and infection of oligodendrocytes which causes demyelination
362
When HIV/AIDS patients have a dropping CD4 count, what drugs are normally started to prevent TB? What about PCP and CNS toxoplasmosis? *Mycobacterium avium *complex?
TB - isoniazid;
PCP and CNS toxoplasmosis - TMP/SMX;
Disseminated *Mycobacterium avium* - Azithromycin
363
What infections are a solid organ transplant recipient most at risk of within the first month?
Bacterial surgical site infection and nosocomial infections
364
When do most opportunistic infections, excepting EBV and community acquired infections, appear in an immunosuppressed solid organ transplant recipient? When can EBV and community acquired infections be expected?
1-12 months after the transplant; EBV and community acquired infections appear more than 6 months afterward
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365
What is given as prophylaxis during a period of high immunosuppression in a solid organ transplant recipient to preven infection by *Pneumocystis jirovecii*?
TMP-SMX
366
What is done to prevent CMV infection in a solid organ transplant recipient?
CMV is monitored by PCR frequently and ganciclovir is started and immunosuppression decreased if it turns positive
367
Is prophylaxis available for solid organ transplant recipients to prevent EBV infection?
No, it is monitored by PCR and immunosuppression is decreased if the PCR is positive
368
What are the main pathogens that chemotherapy patients with neutropenia are most at risk for?
Gram-negative bacteria e.g. *Pseudomonas*, *Candida*, and *Aspergillus *and other filamentous fungi
369
What is the laboratory definition of neutropenia?
Absolute neutrophil count below 500 cells/mm3
370
What is the approach to a patient that develops fever after neutropenia from chemotherapy?
1) Broad spectrum antibiotic wtih activity against *Pseudomonas*, e.g. cefepime
2) possible vancomycin, aminoglycosides or fluconazole if MRSA, gram negatives, or *Candida* respectively are suspected
3) if neutropenia is prolonged, start antifungal against *Aspergillus*
371
What happens to the risk of invasive pulmonary aspergillosis if neutropenia contines for more than a few weeks?
It trends close to 80%
372
When a patient receives a fully ablative bone marrow transplant, does he or she retain any of the past immune memory? What about vaccines?
All past immune memory is lost; past vaccines are no longer protective
373
What family of viruses do both JC virus and BK virus belong to? Are they rare or ubiquitous?
Polyoma viruses; they are ubiquitous and cause diseased in immunodeficient hosts
374
What is the organism pictured here that is responsible for this skin infection in a child? Acid fast staining is employed in the upper right. What does this infection reveal about the immunocompetency of the child?
![]()
*Nocardia*; the child is immunodefecient, perhaps due to a disorder of phagocytic function (chronic granulomatous disease)
375
What laboratory features do *Nocardia* and *Actinomyces* share? How can they be differentiated?
Both are gram-positive, branching, filamentous and slow-growing rods;
while *Nocardia* is a strict aerobe, *Actinomyces* can grow in either condition, and *Nocardia* is weakly acid-fast staining while *Actinomyces* does not stain
376
In patients with primary immunodeficiency, does the opportunistic pathogen that eventually presents reveal something about which kind of immunodeficiency the patient has?
Yes, depending on the organism, severity, and recurrence
377
What eye infection is this? How painful is it?
Acanthamoeba keratitis; extremely painful
378
What is the most common retinal infection in the US?
*Toxoplasmosis gondii*
379
How can infection spread from the upper respiratory tract to the eye?
Via the nasolacrimal duct
380
What are two methods of parenteral transmission of ocular infections?
Transplacental passage and direct contact in the birth canal during delivery
381
What two organisms are significant for eye infection related to contact lens hygiene?
*Acanthamoeba* and *Pseudomonas aeruginosa*
382
What bacterium is associated with eye infections following trauma with soil or vegetable matter?
*Bacillus cereus*
383
What eye infection is associated with faulty sterilization of surgical instruments?
*Mycobacterium chelonei*
384
What are two significant bacterial causes of conjunctivis?
*Strep pyogenes *and *Neisseria gonorrhoeae*
385
What are two significant viral causes of conjunctivitis?
*Adenovirus* and *Herpesvirus*
386
What is the presentation of *Neisseria gonorrhoeae* infection of the eye?
Hyperacute conjunctivitis with profuse yellow exudate, and it can perforate the eye
387
What broad category of eye infection is this?
Blepharoconjunctivitis: the eyelids are inflamed (blepharitis) along with the conjunctiva
388
What is always treated concurrently with *N. gonorrheae* infection of the conjunctiva?
*Chlamydia*, since coinfection rates are ~30%
389
What kind of conjunctivitis is caused by chlamydia? How is it treated?
Inclusion conjunctivitis (named after the inclusion bodies seen in histological preparations); oral tetracycline, doxycycline, erythromycin, or azithromycin
390
What is the leading cuase of preventable blindness in the world, mostly in developing countries? What is the vector for it? What bacterium causes it? How is it treated?
Trachoma; housefly; *Chlamydia trachomatis*; topical and oral tetracycline
391
How is trachoma different from inclusion conjunctivitis, since both are caused by *Chlamydia* species?
Trachoma is on the inner surface of the eyelid, while inclusion conjunctivitis affects the conjunctiva
392
What is the #1 risk factor for bacterial keratitis in the US?
Contact lens wear, particuarly overnight use
393
What are the two most common organisms causing bacteria keratitis?
*Staph aureus* and *Pseudomonas aeruginosa*
394
How does bacteria enter the cornea to cause keratitis, which is exacerbated by contact lens wear overnight?
Corneal abrasions
395
What condition is seen here that was caused by contaminated contact lens wear overnight?
Bacterial keratitis, probably due to *Pseudomonas* or *Staph*
396
How is bacterial keratitis diagnosed?
Culture of the bacterium from exudate or the offending contact lens source
397
How is bacterial keratitis treated?
Topical antibiotics because they penetrate the cornea better than orals: fluoroquinolones like moxifloxacin, or vancomycin and tobramycin
398
What is the primary adverse effect of topical antibiotics applied to the cornea?
The preservative can be toxic to the epithelium
399
Are topical antibiotics on the cornea absorbed systemically?
Only in minute quantities, but still check for allergies and contraindications
400
Which herpesviruses affect the eye?
Herpes simplex virus 1 and 2, varicella zoster virus, EBV, CMV, and Kaposi sarcoma-associated virus (HHV-8)
401
What tissue is this? What infection is this?
This is the cornea; Herpes simplex keratitis
402
What stain was used here to visualize a multinucleated epithelial cell in a case of keratitis? What virus is suspected?
Giemsa stain; Herpes simplex
403
Should a topical or oral antiviral be used against herpes simplex keratitis?
Either can be used
404
What two topical antivirals can be used for herpes simplex keratitis?
Trifluridine and ganciclovir
405
What virus has caused this outbreak, which comes with a risk of keratitis?
Herpes zoster (varicella zoster virus)
406
Is fungal keratitis more frequent in warmer or cooler areas of the US?
Warmer areas
407
What is an environmental and a pharmacological risk factor for fungal keratitis?
Trauma to the cornea with a plant or vegetable is the leading risk factor, followed by topical steroid use
408
What type of keratitis is likely here, which followed trauma to the eye with vegetable material?
Fungal keratitis
409
What is the most common cause of fungal keratitis in the southern US? How is it treated?
Filamentus *Fusarium*; Natamycin drops
410
Besides amphotericin B and Natamycin, what class of antifungals is also used against fungal keratitis?
Triazoles, e.g. ketoconazole, fluconazole, itraconazole, and voriconazole
411
What part of this eye is inflamed? What does this layer cover?
The conjunctiva; it covers the sclera, the white part of the eye
412
What part of the eye is inflamed in keratitis?
The cornea
413
What is an infection of the whole eyeball called? What is the incidence post surgery? How is it treated
Endopthalmitis; 1/1000 after surgery; intravitreal injection of antibiotics or vitrectomy
414
What is this emergency condition called?
Endopthalmitis, in this case caused by *Staph*
415
What are the key clinical signs of inhalational anthrax?
Widened mediastinum with fever and sepsis
416
What agent of bioterrorism presents with a widened mediastinum with fever and sepsis?
Inhalational anthrax
417
What agent of bioterrorism creates a localized skin lesion with a depressed black scab?
Cutaneous anthrax
418
What potential agent of bioterrorism causes a vesicular/pustular rash starting on the hands, covering the body and with all lesions at the same stage of development?
Smallpox
419
What is the bacterium that causes anthrax?
*Bacillus anthracis*
420
What is the gram staining and shape of anthrax? Does it form spores? Is it an aerobe or an anaerobe?
Large gram positive rod; spore forming; facultative anaerobe
421
What are the three methods of infection by anthrax?
Inhalation, ingestion or inoculation through skin
422
Does *Bacillus anthracis* have a capsule? What two toxins does it produce?
Yes; edema toxin and lethal factor
423
How does anthrax lethal toxin cause cell death?
It is a zinc metalloprotease that stimulates inflammatory cytokine production
424
How long does it take for cutaneous anthrax to manifest? What is the prognosis with treatment?
1-2 weeks; good prognosis with treatment (very rare mortality)
425
Which manifestation of anthrax is responsible for the most deaths? How long does it take for symptoms to present?
Inhalational anthrax; up to 60 days after inhalation
426
Where does anthrax replicate after spores are inhaled?
Macrophages phagocytose the spores and carry them to lymph nodes, where germination occurs weeks later
427
Can anthrax spores be aerosolized? Can infections be spread person to person?
Yes, and they are odorless and colorless; no infectivity between humans
428
What antibiotics are used against anthrax?
Penicillin and ciprofloxacin
429
What organism causes plague? How is it transmitted to humans from its reservoir in rats?
Ye*rsinia pestis*, a member of *Enterobacteriaceae*; fleas
430
What is this bacterium with the "safety-pin" appearance, transmitted via fleas?
*Yersinia pestis* or plague
431
What is the genomic makeup of the variola virus (Smallpox)? How infectious is it? How is it spread between persons?
Large DNA virus; very infectious, only a few virions produces symptoms; spread via droplets or aerosols or direct/indirect contact
432
What disease is caused by the variola virus?
Smallpox
433
How long is it before the variola virus produces symptoms? What are they?
8 days; fever, malaise, headache, back ache, delirium
434
What is the mortality of smallpox? What causes death?
15-40%; usually secondary to circulating immune complexes or bacterial superinfection
435
Why do we not vaccinate for smallpox?
The last naturally occurring case was in 1977 in Somalia
436
How is the chickenpox rash different from the smallpox rash?
The chicken pox rash has lesions in different stages (papules, vesicles, and crusts) and rarely involves the palms and soles, while the smallpox rash always presents with lesions in the same stage with no crusing and some are usually umbilicated.
Left, chickenpox; right, smallpox
437
What vaccine did Edward Jenner discover in the 18th century that was active against smallpox? How quickly must it be given after smallpox exposure to confer immunity?
The cowpox virus given as a vaccine provides immunity against smallpox; Within 4 days
438
Is there a proven treatment for smallpox?
No, although Cidofovir, a DNA polymerase inhibitor, may have some efficacy
439
What poxvirus outbreak occurred in 2003 as a result of owners of pet prairie dogs?
Monkeypox
440
What spore-forming bacillus that is naturally found in soil produces flaccid paralysis and is associated with improperly canned foods?
*Clostridium botulinum*
441
How toxic is the botulinum toxin produced by *Clostridium botulinum*?
Very, 1 gram could kill a million people
442
What are symptoms or signs of inhalational botulism?
Double/blurred vision, drooping eyelids, slurred speech, difficulty swallowing, and muscle weaknesses or flaccid paralysis, including paralysis of respiratory muscles
443
What is the treatment for inhalational botulism?
Supportive and use of antitoxin
444
What organism causes tularemia? What is its shape and gram staining? How is it transmitted naturally?
*Francicella tularensis*; Poorly staining gram negative coccobacilli; by ticks
445
What are the three major causes of viral hemorrhagic fevers?
Filoviruses like Ebola and Marburg virus, and Arena viruses like Lassa fever
446
How are most round worms treated, as a general rule?
Benzimidazoles, e.g. albendazole
447
How are most flat worms treated, as a general rule?
Praziquantel
448
How are most anaerobic protozoans like *Entamoeba, Giardia,* and *Trichomonas* treated, as a general rule?
Tinidazole and metronidazole
449
Is the treatment for *Ascaris* different from that for hookworms?
No, both should be prescribed mebendazole or albendazole
450
What drug can be used to treat all of: *Enterobius*, *Strongyloides*, *Trichurius*, hookworm, and *Ascaris*?
Albendazole
451
Which roundworm species enter the body by penetrating the skin? Which one is significant for causing hyperinfection syndrome?
*Strongyloides* and hookworms; *Strongyloides* can cause hyperinfection syndrome
452
What are adverse effects of albendazole?
Abdominal pain, reversible hair loss (alopecia), and liver damage (high liver enzymes)
453
In the case of a severe hyperinfection syndrome caused by *Strongyloides*, what alterations in treatment may be made?
Ivermectin, albendazole, and thiabendazole are still administered but possibly as a rectal enema to increase exposure of the parasite to the drug
454
What is the mechanism of ivermectin? What organisms is it the drug of choice for?
It is neurotoxic to the worm, keeping a chloride channel open and causing paralysis; Filiarisis causing river blindness, and sometimes *Strongyloides*
455
What are two drugs that are active against filariasis?
Diethylcarbamazine (DEC) and ivermectin
456
What class of organisms is praziquantel usually used for?
Flatworms (cestodes)
457
When might albendazole be used instead of praziquantel for a tapeworm infection? Why?
In the case of neurocysticercosis (*Taenia solium* in the brain); albendazole has better CNS penetration
458
What are all cases of schistosomiasis treated with?
Praziquantel
459
What is this condition? What parasite spread by mosquitos is it indicative of, in conjunction with anemia?
Icterus; malaria
460
How widespread is malarial resistance to chloroquine?
Very widespread (in red)
461
What must be monitored when using IV quinidine?
Cardiotoxicity, since it can cause arrhythmias
462
If a patient is taking quinine prophylaxis and they go into a coma, what adverse effect may have occured?
Hypoglycemia, because it stimulates pancreatic insulin secretion
463
In the case of chloroquine resistance, what antibiotic can usually used for prophylaxis against and treatment of malaria? What is the adverse effect associated with this treatment?
Doxycycline in conjunction with quinine; photosensitivity
464
Is mefloquine still used to treat or as prophylaxis for malaria?
While the weekly dosing is convenient, it has serious potential side effects (e.g., Stevens-Johnson syndrome) and is no longer preferred, only being used for pregnant women as it is the only non-teratogenic anti-malarial
465
What is atovaquone and proguanil used to treat? What is the only side effect of concern?
Malaria; GI intolerance, so take it with food
466
What antimalarial combination is an effective prophylaxis but may be too expensive for extended trips, and has few side effects except for GI intolerance?
Atovaquone and proguanil
467
What treatment is used for severe, chloroquine resistant *falciparum* malaria?
IV quinidine and IV doxycycline
468
What is IV artesunate used to treat, for which it was recently approved by the FDA? Is resistance to this drug yet known?
Malaria; no resistance yet reported
469
When a malaria patient shows schizonts in a peripheral blood smear, what organism is less likely to be the culprit? What change should be made in treatment as opposed to the treatment for that organism?
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*P. falciparum* is less likely and *P. ovale* and *P. vivax* are more likely; primaquine is used to kill schizonts
470
What enzymatic deficiency is a contraindication for primaquine? Why?
G6PD deficiency; it can cause hemolytic anemia
471
What is the preferred treatment for babesia? Why is it preferred over clindamycin and quinine?
Atovaquone with azithromycin; fewer side effects
472
What is the drug of choice against *Entamoeba histolytica* infections? What is an important dietary guideline for patients on this drug?
Metronidazole; no alcohol should be consumed
473
What can be added to metronidazole for treatment of amebiasis to kill cysts with infectious particles?
Iodoquinol
474
What treatment options are shared by *Giardia*, *Entamoeba*, and *Trichomonas*? What is their mechanism?
Metronidazole and tinidazole; inhibition of DNA synthesis
475
What is the major toxicity of amphotericin B?
Nephrotoxicity, with potential electrolyte abnormalities
476
What insect-borne protozoan parasite infection can be treated with amphotericin B?
Leishmaniasis
477
What is a typical FDA-approved treatment for Leishmaniasis that is not also used against fungi?
Pentavalent antimonials like sodium stibogluconate and meglumine antimonate
478
What are sodium stibogluconate and meglumine antimonate used to treat?
Leishmaniasis
479
How is South American trypanosomiasis treated? Is the drug available in the US?
Benznidazole and nifurtimox; only via the CDC
480
Is the treatment for South American and African trypanosomiasis the same?
No
481
What is the first line therapy for an AIDS patient presenting with ring enhancing lesions in a brain CT? What organism is implicated?
Pyrimethamine and sulfadiazene; *Toxoplasma gondii*
482
What are pyrimethamine and sulfadiazene used to treat? What are the adverse effects associated with these drugs?
Toxoplasmosis, usually in an immunocompromised patient; pancytopenia and a skin reaction called Stevens-Johnson syndrome
483
Can *Pneumocystis jirovecii* be grown in culture? How is it diagnosed? How is it treated?
No; direct fluorescence antibody; TMP-SMX
484
Who will you need to call to treat kinetoplastids like *Trypanosoma?*
The CDC, since the treatments are not normally available in the US
485
What is the top unnatural cause of death in low-income countries as reported by the WHO in 2008?
Lower respiratory infection
486
What are the top two risk factors for the global distrubtion of disease in low and middle income persons?
Being underweight and unsafe sex
487
What patient population does Doctors Without Borders focus on? How much does treatment cost?
Poorest, sickest patients worldwide; free to patient
488
What is being done here on this patient that may have sleeping sickness in Sudan?
A lumbar puncture to retrieve CSF which can determine if the parasites have reached the CSF
489
What is the relationship between severity and the risk of infection for the fetus over the course of a pregnancy?
Inverse
490
Over the course of a pregnancy, during what period are infections worst for both mother and fetus? What period is typical for a better prognosis for the child at the expense of the fetus? What period is typical for a better prognosis for the mother at the expense of the fetus?
1st trimester – bad for mother and fetus;
3rd trimester – bad for mother, fetus may be savable;
2nd trimester – bad for fetus, mother is safer
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491
What viral pathogens are capable of vertical transmission?
5 H's: HIV, Herpesviruses, Hep B, Hep C, HPV, ...
Rubella,
and Parvovirus B19
492
What protozoan parasite is most at risk of crossing from mother to fetus?
*Toxoplasma gondii*
493
What bacteria can be transmitted from mother to fetus during pregnancy?
CLESS mnemonic:
Chlamydia,
Listeria,
E. Coli,
Syphilis,
and Strep (Group B)
494
What is the key strategy for preventing neonatal infection of HIV? What viral co-infection is a risk for perinatal infection?
Decrease viral titers in the 3rd trimester; Hepatitis C
495
What is the efficacy for antiretroviral treatment for vertical transmission of HIV to neonates? Is it more or less effective than C-section delivery alone?
Near 100%; much more effective
496
What bacterium is a common colonizer of the human GU tract, found in 10-30% of pregnant women, and was the most common cause of sepsis and meningitis in infants \<3mo old in the 1970s? How is vertical transmission prevented?
*Strep agalactiae* (group B Strep); screening at 26-28 weeks, and then treatment during labor or before C-section
497
What is the prevention strategy for neonatal herpes?
Preventing maternal acquisition during pregnancy, and avoiding exposure to herpetic lesions during delivery
498
For a pregant woman with active HSV displaying genital lesions, what is the recommendation for treatment or delivery?
C-section delivery
499
What are the ToRCHSV infections?
A group of *in utero* infections that present similarly, including ocular findings and rash
500
What *in utero* infections present similarly with ocular findings and a rash?
Use the mnemonic ToRCHSV:
*Toxoplasma gondii*
Rubella
Syphilis
Cytomegalovirus
HSV
Syphilis
Varicella
