Bacterial & fungal infection (Med Micro 3) Flashcards
(140 cards)
1
Q
What is india ink staining used for?
A
It is a specific test for cryptococcal meningitis.
A negative result suggests the absence of cryptococcal meningitis.
2
Q
What is the sensitivity of india ink staining?
A
Around 85%.
This means it fails to diagnose 1/6 true cases.
3
Q
What has superseded india ink staining in diagnosing cryptococcal meningitis?
A
Cryptococcal antigen testing.
This test has far higher sensitivity and specificity, both >95%.
4
Q
Fill in the blank: The CSF results of very low glucose and very high protein should raise suspicion of _______.
A
cryptococcal and tuberculous meningitis.
5
Q
What are common manifestations of cryptococcal disease?
A
Rash and pulmonary involvement.
6
Q
What is the typical timeframe for most cases of TB reactivation?
A
Within 2 years
This timeframe highlights the importance of monitoring individuals who may be at risk for tuberculosis reactivation.
7
Q
When should screening for migrants be conducted according to the CDC?
A
Within 5 years or if high risk
High-risk factors include incarceration, which increases the likelihood of TB exposure.
8
Q
What is the causative agent of Tetanus?
A
Clostridium tetani
Clostridium tetani is an anaerobic bacterium that produces a potent neurotoxin.
9
Q
How is Tetanus transmitted?
A
Bacteria enter the body through wounds, such as deep cuts, puncture wounds, or burns
Tetanus is not transmitted person-to-person but rather through contaminated wounds.
10
Q
What is the ‘spatula test’ used for?
A
A bedside diagnostic tool for Tetanus that involves touching the oropharynx with a spatula
A positive result is indicated by a reflex spasm of the masseters.
11
Q
What is the primary method of preventing Tetanus?
A
Vaccination, with routine childhood vaccinations and booster shots recommended for adults
Infection does not provide natural immunity.
12
Q
What is the treatment for Tetanus?
A
TIG (tetanus immunoglobulin), wound care, antibiotics (metronidazole), active vaccination, benzodiazepines for muscle rigidity
Treatment is considered a medical emergency.
13
Q
What bacterium causes Leptospirosis?
A
Leptospira bacteria
Leptospira is a spirochete bacterium responsible for this zoonotic disease.
14
Q
How is Leptospirosis transmitted?
A
Contact with the urine or bodily fluids of infected animals or contaminated water or soil
This is often a risk for those in high rainfall or flooding areas.
15
Q
What are common symptoms of Leptospirosis?
A
Flu-like symptoms including fever, headache, chills, and muscle aches
Severe cases may lead to kidney or liver failure.
16
Q
What is the primary treatment for Leptospirosis?
A
Doxycycline
Early treatment can significantly reduce complications.
17
Q
What bacterium causes Scrub Typhus?
A
Orientia tsutsugamushi
This bacterium is transmitted through bites from infected larval trombiculid mites.
18
Q
What are the symptoms of Scrub Typhus?
A
Fever, headache, body aches, rash, eschar at the bite site
Symptoms may vary, making diagnosis challenging.
19
Q
What is the recommended treatment for Scrub Typhus?
A
Doxycycline
This treatment is effective if administered early.
20
Q
What is the causative agent of Diphtheria?
A
Corynebacterium diphtheriae (toxin-producing strains)
The disease can lead to severe complications due to the toxin produced.
21
Q
How is Diphtheria transmitted?
A
Respiratory droplets and direct contact with skin lesions
Close contact with an infected person increases the risk.
22
Q
What are the clinical features of respiratory diphtheria?
A
Sore throat, low-grade fever, ‘bull neck’ from cervical lymphadenopathy and edema
These symptoms are indicative of the disease.
23
Q
What is the treatment for Diphtheria?
A
Diphtheria antitoxin (DAT) and antibiotics (Erythromycin or Penicillin)
Immediate administration of antitoxin is critical.
24
Q
How many cases of TB per year? How many deaths? How many co-infected with HIV?
A
1 million deaths and 10 million cases per year, with 1 million co-infected with HIV
India, China, and Russia have the highest rates of Multi-Drug Resistant (MDR) TB.
25
Name 3 non-TB mycobacterium?
* Mycobacterium ulcerans → Buruli ulcer
* Mycobacterium avium complex (MAC) → Disseminated disease in immunocompromised individuals
* Mycobacterium leprae → Leprosy (Hansen’s disease)
## Footnote
These organisms can cause significant health issues, particularly in vulnerable populations.
26
What is latent TB?
A state of persistent immune response to Mycobacterium tuberculosis antigens without active disease
## Footnote
Latent TB can reactivate later if the immune system is weakened.
27
How is TB primarily transmitted?
Droplet spread: inhaled, inoculated, or ingested
## Footnote
Proximity and duration of exposure significantly affect transmission risk.
28
What is the Ghon focus?
A caseating granuloma in the lung
## Footnote
If it also involves lymph nodes, it becomes known as the Ghon complex.
29
What are the clinical features of pulmonary TB?
* Cough duration > 2 weeks
* Fever
* Weight loss
* Night sweats
## Footnote
Severe cases can present with acute shortness of breath.
30
What are the features of TB pleural tap?
* Straw-coloured exudates
* Elevated lactate dehydrogenase levels
* Markedly elevated protein levels
* Lymphocyte predominance
## Footnote
These findings are indicative of pleural TB.
31
What are key side effects of Rifampicin?
* Hepatotoxicity
* Orange/red discoloration of body fluids
* Flu-like syndrome
* Induction of cytochrome P450 enzymes
## Footnote
Monitoring liver function is crucial during treatment.
32
What is Directly Observed Treatment (DOT)?
A treatment approach for TB where healthcare workers observe patients taking their medication
## Footnote
It is particularly important for high-risk individuals to ensure adherence.
33
What is the primary pathogen responsible for leprosy?
Mycobacterium leprae
## Footnote
This bacterium has a long incubation period, leading to challenges in diagnosis.
34
What is the incubation period for leprosy?
3-20 years
## Footnote
The long incubation period complicates contact tracing and early diagnosis.
35
What is the treatment for leprosy?
Multi-drug therapy (MDT) for 6-12 months including rifampicin, clofazimine, and dapsone
## Footnote
Treatment is provided globally and is effective in preventing disease progression.
36
What are the characteristics of lepromatous lesions?
Symmetrical lesions, leonine facies, infiltrated earlobes
## Footnote
Lepromatous leprosy presents with distinct facial features and skin changes.
37
What type of lesions are associated with secondary syphilis?
Generalized rash, systemic signs
## Footnote
Secondary syphilis often presents with a widespread rash and various systemic symptoms.
38
What are the characteristics of histoid lepromatous leprosy?
Well-defined, skin-colored or erythematous, shiny papules and subcutaneous plaques, most infectious
## Footnote
Histoid lepromatous leprosy is a more infectious form of the disease.
39
What is the recommended duration for paucibacillary leprosy treatment?
6 months
## Footnote
Treatment duration is essential for effective management of leprosy.
40
What is the recommended duration for multibacillary leprosy treatment?
12 months
## Footnote
Multibacillary leprosy requires a longer treatment period due to the higher bacterial load.
41
What is the mechanism of action of rifampicin?
Inhibits DNA-dependent RNA polymerase → blocks bacterial RNA synthesis
## Footnote
Rifampicin is a key antibiotic used in leprosy treatment.
42
What is the usual dose of rifampicin for leprosy treatment?
10 mg/kg/day
## Footnote
Correct dosing is crucial to ensure efficacy and minimize side effects.
43
What is the dose range for dapsone?
1–2 mg/kg/day
## Footnote
Dosing can vary based on patient factors.
44
What are some side effects of dapsone?
* DRESS syndrome (Drug Rash with Eosinophilia and Systemic Symptoms)
* Risk of haemolytic anaemia in G6PD deficiency (reduce dose)
## Footnote
Monitoring for specific side effects is essential, especially in at-risk populations.
45
What is the typical dosing regimen for clofazimine?
Usually 50 mg daily + 300 mg monthly in MDT
## Footnote
Multi-drug therapy (MDT) is the standard approach in leprosy treatment.
46
What are some side effects of clofazimine?
* Skin hyperpigmentation
* Dry skin
* Generally well tolerated
## Footnote
While clofazimine has side effects, it is usually well tolerated by patients.
47
What are lepra reactions?
Episodes of sudden increase in the activity of the disease due to an alteration in the immunological status
## Footnote
These reactions require careful monitoring and management to prevent complications.
48
What are the two forms of lepra reactions?
* Type 1 (reversal reaction)
* Type 2 (erythema nodosum leprosum)
## Footnote
Understanding the types of reactions is crucial for treatment and management.
49
What is the treatment for lepra reactions?
Prednisolone for at least 5 months, tapered by 5mg every 2 weeks
## Footnote
Timely treatment of lepra reactions is essential to prevent nerve damage.
50
How long after treatment does leprosy become non-infectious?
1 month
## Footnote
Rapidly becoming non-infectious is a key goal of effective leprosy treatment.
51
What is the pathogen responsible for typhoid fever?
Typhoidal salmonella - Typhi
52
In what age group does 40% of typhoid cases occur?
< 5 years old
53
What organ can be a reservoir of chronic infection in typhoid patients?
Gallbladder
54
What is a characteristic fever pattern in typhoid fever?
Step-ladder fever, gradually rising over the first week; sustained
55
When do "Rose Spots" usually appear in typhoid fever?
'Rose Spots' usually appear during the second week
56
What is the 'Typhoid state' characterised by?
Headache, confusion, delirium
57
What is Faget's sign?
Relative bradycardia (Faget sign) indicates a lower-than-expected heart rate for the degree of fever - seen in typhoid fever.
58
What are two major complications of typhoid fever?
* GI bleeding
* Intestinal perforation
59
What is considered the test of choice for diagnosing typhoid fever?
Blood culture
60
What factors influence the choice of antibiotics for typhoid fever?
Strain and local resistance patterns
61
List the three types of vaccines available for typhoid fever.
* Ty21a (Oral attenuated strain)
* Vi vaccine (Vi polysaccharide antigen)
* Vi conjugate vaccine
62
What is the pathogen responsible for non-typhoidal salmonella infections?
Salmonella enterica subspecies (excluding Typhi & Paratyphi)
63
What is the primary mode of transmission for non-typhoidal salmonella?
Contaminated food/water, fecal-oral route
64
What are the two main types of non-typhoidal salmonella infections?
* Gastroenteritis
* Invasive NTS (iNTS)
65
Which region is identified as having a high burden of non-typhoidal salmonella infections?
Sub-Saharan Africa
66
What is the mortality risk associated with invasive NTS disease?
High (10–25%)
67
What is the causative agent of melioidosis?
Burkholderia pseudomallei
68
What is the primary reservoir for Burkholderia pseudomallei?
Soil and surface water (especially rice paddies)
69
What are the clinical features of acute melioidosis?
* Bacteraemia
* Sepsis
* Pneumonia
* Abscesses
70
What is the first-line antibiotic treatment for acute melioidosis?
* Ceftazidime
71
What is the causative agent of brucellosis?
Brucella spp.:
* B. melitensis (goats/sheep) – most pathogenic to humans
* B. abortus (cattle)
* B. suis (pigs)
* B. canis (dogs)
72
What are the common clinical features of acute brucellosis?
* Undulant fever
* Malaise
* Sweats
* Arthralgia
* Myalgia
73
What is a significant diagnostic test for brucellosis?
SAT (Standard Agglutination Test)
74
What is the primary treatment regimen for uncomplicated brucellosis?
Doxycycline + rifampicin for 6 weeks
75
What is the causative agent of plague?
Yersinia pestis
76
What are the three clinical forms of plague?
* Bubonic
* Septicaemic
* Pneumonic
77
What is the incubation period for plague?
2–7 days
78
Which diagnostic method shows a bipolar appearance for Yersinia pestis?
Microscopy on Wayson/Methylene blue stain
79
What is the treatment for plague if started within 24 hours?
Gentamicin + Doxycycline
80
What is the historical significance of the second pandemic of plague?
Black Death, 14th C; killed 1/3 of Europe (~100 million)
81
Who is most at risk of developing brucellosis?
Vets, abattoir workers, lab staff, farmers
82
How is brucellosis transmitted?
ingestion (unpasteurised dairy); inhalation (lab, abattoirs); percutaneous (handling animals/tissues)
83
In which countries is plague endemic?
DRC, Madagascar, China, Mongolia, Uganda, USA - Madagascar: 41% of world cases.
84
What is the key vector in the transmission of plague?
Fleas, esp. Xenopsylla cheopsis.
85
What is the most common clinical form of plague?
Bubonic plague (85%)
## Footnote
Characterized by sudden fever, headache, and painful lymphadenopathy (buboes), usually in the inguinal area. It is not contagious.
86
What are the symptoms of Bubonic plague?
Sudden fever, headache, painful lymphadenopathy (buboes)
## Footnote
Usually inguinal and not contagious.
87
Name other forms of plague
Septicaemic
Pneumonic
Meningeal
## Footnote
May complicate untreated bubonic plague.
88
What is Coccidioidomycosis also known as?
Valley Fever, Desert Fever, Desert Rheumatism
## Footnote
Coccidioidomycosis is caused by Coccidioides immitis and C. posadasii.
89
What are the causative pathogens of Coccidioidomycosis?
Coccidioides immitis and C. posadasii
## Footnote
These are dimorphic fungi.
90
Which geographical areas are most affected by Coccidioidomycosis?
Southwestern USA, especially Arizona (70%), California (25%), New Mexico, Texas, Mexico, Central & South America
## Footnote
Coccidioidomycosis is prevalent in dry, dusty areas.
91
How is Coccidioidomycosis transmitted?
Inhalation of arthroconidia
## Footnote
Can occur with short exposure or environmental disruption.
92
What is the incubation period for Coccidioidomycosis?
1–4 weeks
## Footnote
Reactivation can occur even decades later.
93
What are the clinical forms of Coccidioidomycosis?
1. Acute Pulmonary
2. Chronic Pulmonary
3. Disseminated
## Footnote
Complications may include meningitis.
94
What is the biohazard level for culturing Coccidioides?
Biosafety Level 3
## Footnote
Very high lab hazard; do NOT culture in routine labs.
95
What is the causative agent of Histoplasmosis?
Histoplasma capsulatum
## Footnote
There are two varieties: var. capsulatum (global) and var. duboisii (African type).
96
Where is Histoplasmosis endemic?
USA (Ohio–Mississippi River Valleys), Southeast Asia, Africa
## Footnote
It is often found in regions with bat/bird droppings.
97
What are the risk activities for contracting Histoplasmosis?
Caving, demolition, cleaning droppings, roofing, deforestation
## Footnote
These activities involve exposure to contaminated soil.
98
What are the clinical forms of Histoplasmosis?
1. Acute Pulmonary
2. Chronic Pulmonary
3. Disseminated
## Footnote
Other forms include mediastinal lymphadenitis and granuloma.
99
What is the treatment for moderate to severe acute Histoplasmosis?
Liposomal AmB followed by itraconazole for 12 weeks
## Footnote
Steroids may be added if necessary.
100
What is the causative agent of Paracoccidioidomycosis?
Paracoccidioides brasiliensis and Paracoccidioides lutzii
## Footnote
These are also dimorphic fungi.
101
In which region is Paracoccidioidomycosis endemic?
South America, especially Brazil, Colombia, Venezuela, Ecuador, Argentina
## Footnote
It thrives in humid, rural environments.
102
What are common clinical features of Paracoccidioidomycosis?
Pulmonary disease, mucocutaneous lesions, skin lesions
## Footnote
Mucocutaneous lesions often present as painful ulcers.
103
What is the histopathological feature of Paracoccidioidomycosis?
Large yeast cells with multiple buds
## Footnote
They have a characteristic pilot wheel or Mickey Mouse appearance.
104
What is the treatment for mild to moderate Paracoccidioidomycosis?
Itraconazole for 6–12 months
## Footnote
Severe or disseminated cases may require amphotericin B followed by itraconazole.
105
What is the triad of symptoms for Mycetoma?
Painless mass, draining sinuses, granules
## Footnote
It presents a risk of disability.
106
What is the treatment for Chromoblastomycosis?
Itraconazole long-term, cryotherapy, surgery
## Footnote
It is characterized by warty or cauliflower-like skin lesions.
107
What is the causative agent of Talaromycosis?
Talaromyces marneffei
## Footnote
It mimics tuberculosis and is systemic in HIV.
108
What is the treatment for Cryptococcosis?
Amphotericin B + flucytosine for induction, fluconazole for consolidation
## Footnote
It commonly causes meningitis in immunocompromised patients.
109
Name the key groups of Rickettsia.
* Spotted Fever Group (SFG)
* Typhus Group
* Scrub typhus group
## Footnote
Each group is associated with specific diseases and vectors.
110
What is the primary vector for the Spotted Fever Group?
Ticks
## Footnote
Other vectors include lice for R. prowazekii and fleas for R. typhi.
111
What is the typical incubation period for Rickettsial infections?
1-2 weeks
## Footnote
This period can vary depending on the specific infection.
112
What are the clinical features of Rickettsial infections?
* Non-specific febrile illness
* Relative bradycardia
* Rash
* Eschar (in some cases)
* Severe complications (e.g., meningoencephalitis)
## Footnote
Clinical features can vary widely among different infections.
113
Which Rickettsia species is responsible for Rocky Mountain Spotted Fever?
Rickettsia rickettsii
## Footnote
This disease is particularly dangerous and has a high fatality rate.
114
How is Rickettsial infection diagnosed?
* Serology (IFA, ELISA)
* PCR
* Skin biopsy
## Footnote
Culture is challenging due to the intracellular nature of the organisms.
115
What is the first-line treatment for Rickettsial infections?
Doxycycline
## Footnote
Doxycycline is effective for all ages and severities and shows improvement within 48 hours.
116
What preventive measures can be taken against Rickettsial infections?
* Vector control (ticks, fleas, lice)
* Personal protective measures in endemic areas
## Footnote
Awareness and prevention are key to controlling outbreaks.
117
Fill in the blank: The causative agent of African Tick Bite Fever is _______.
Rickettsia africae
## Footnote
This species is associated with multiple inoculation sites and eschar formation.
118
What kind of vector transmits Murine Typhus?
Fleas
## Footnote
Fleas, specifically Xenopsylla cheopis, are the primary vector for this disease.
119
Which species causes Scrub Typhus?
Orientia tsutsugamushi
## Footnote
Although related, it is not classified as a true Rickettsia.
120
What is the geographic distribution of Rocky Mountain Spotted Fever?
Americas (USA, Brazil, Colombia)
## Footnote
This disease is primarily found in North and South America.
121
What is the geographic distribution of Epidemic Typhus?
Worldwide (especially during war/famine)
## Footnote
Epidemic Typhus outbreaks are often linked to socio-economic crises.
122
True or False: There is a widely available vaccine for Rickettsial infections.
False
## Footnote
Some experimental vaccines exist, but none are widely available.
123
What type of bacteria is Anthrax?
Aerobic, gram positive bacteria
## Footnote
Anthrax sporulates on blood plate and may require a specialist library to identify.
124
How is Anthrax transmitted?
Via contact with infected animals/animal products
125
What are the clinical features of cutaneous anthrax?
Necrotic eschar with oedema+++ (gelatinous)
126
What are the cardinal features of inhalational anthrax?
Cardinal's cap meningitis; CFR 50-80%
127
What is the first line treatment for Anthrax?
PO ciprofloxacin
128
What is the duration of treatment for post-exposure prophylaxis in Anthrax?
60 days of ciprofloxacin - unless sensitive to penicillin, then switch to Amox
129
What type of bacteria is Coxiella burnetii?
Gram negative bacterium
130
What are the risk factors for transmission of Coxiella burnetii?
Working with animals/cattle, raw milk, tick-bites
131
What category biothreat is Coxiella burnetii?
Category 3 biothreat agent
132
What is the typical clinical presentation of acute Q-fever?
Fever, fatigue, flu-like symptoms
133
What percentage of Q-fever cases are asymptomatic?
> 50%
134
What is a major complication of chronic Q-fever?
Culture negative endocarditis
135
What makes the diagnosis of Q-fever challenging?
Lack of awareness and delayed results (around two weeks)
136
What is the treatment for chronic Q-fever?
Doxycycline, length depends on risk factors
137
What are the prevention methods for Q-fever?
* Cattle vaccines
* Safe birthing for animals
* Don’t drink raw milk
* Screen pregnant women and newborns
138
What are some causes of culture negative endocarditis?
* Brucellosis
* Bartonella sp
* Coxiella burnetii
* Staphylococcus
* Streptococcus
* E.faecalis
* Whipple's
* Non-TB mycobacteria
139
What percentage of those infected with mycobacterium tuberculosis will develop primary TB infection?
5%
140
Which tests is recommended for monitoring a patient with diphtheria to assess potential complications?
ECG
