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COMLEX STEP 1 2017 > Micro > Flashcards

Micro Flashcards

1
Q

What are the two microoganisms that are:
Gram positive
Catalase negative
alpha hemolytic

how do you tell the apart?

A

Optochin Sensitive, Bile soluble

positive: Strep Pneumonia (Encapsulated)
negative: Strep Viridans (mutans)

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2
Q

What are three organism you become susceptible with sickle cell or after a splenectomy?

which is the most common involved in pneumonia?

A

Encapsulated Organisms

  1. Streptococcus Pneumonia
  2. Haemophilus influenza
  3. Neisseria Meningitidis
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3
Q

How does Parvovirus B19 present in children?

A
  1. “Slapped Cheeks” rash in children
  2. Aplastic crisis in sickle cell disease
  3. fetus - Hydrops fetalis (RBC dectruction)

in adults - pure RBC aplasia and RA-like Sx

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4
Q

What is the most important protective immunologic mechanism against encapsulated organisms?

A

IgG-mediated opsonization

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5
Q

What are three tests that can confirm Cryptococcus neoformans as the cause of meningitis in AIDS patients?

A

Latex particle agglutination - most specific, detects polysaccharide capsular antigen
India Ink - clear halo
Mucicarmine - red inner capsule

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6
Q

24 year old woman shows up to office with copious green vaginal discharge. What is the dx? what is the best dx test?

A

Trichomoniasis
Saline microscopy - motile protozoan
best dx test = Nucleic Acid Amplification test (NAAT)

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7
Q

What is the most common cause of osteomyelitis?

If an african american pt presents w anemia and osteomyelitis which combo should you treat with?

A

Staphylococcus aureus

Ciprofloxacin and Vancomycin

  • -cipro - for salmonella
  • -vanco - s. aureus
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8
Q

Cephalosporins bind to what type of bacterial structure?

A

cephalosporins irreversibly bind to penicillin binding proteins
Transpeptidases = PBP thatcross links peptidoglycans in bacterial cell wall

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9
Q

What viruses cause B cells to enter a immortal stage and maintain the capacity to secrete immunoglobulins?
What type of Abs?

A

Epstein-Barr virus

Heterophile IgM antibodies

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10
Q

What are two bacteria that can cause impetigo?

A

S. aureus

S. pyogenes (GAS)

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11
Q

What systemic symptoms usually follow a Group A Strep infection (impetigo)

what is the first line treatment?

A

facial puffiness
Dark urine
–Poststreptococcal glomerular nephritis (PSGN)

first line Tx: Penicillin

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12
Q

What technique is described:

bacteria fail to decolorize with hydrochloric acid and alcohol after staining carbofuschin?

A

Acid fast staining

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13
Q

What is the bacteria:

gram positive, lancet shaped diplococci?

A

Streptococcus Pneumoniae

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14
Q

What is the main source of rabies in the US?

A

bats

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15
Q

what bacteria is a/w ecthyma gangrenosum (skin patches with necrotic centers and occasional ulceration)

A

Pseudomonas aeruginosa

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16
Q

KOH stain shows large, round yeast with doubly refractory wall, and single broad-based bud

-Ohio and mississippi, river valleys, great lakes

A

Blastomyces dermatitidis

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17
Q

immunosuppressed pt
fungal rhinositis
light microscopy: v-shaped, narrow septate hyphae invading the tissue

A

Aspergillosis fumigatus

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18
Q

How does Isoniazid work?

A

inhibition of mycolic acid synthesis

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19
Q

group of kids get sick at summer camp
present with fever, cough, congestion, sore throat, red eyes, erythematous oropharynx
Crackles present in lower left field upon auscultation

A

Adenovirus

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20
Q

Pyrrolidonyl arylamidase postivity (PYR-positive)

A

S. pyogenes (GAS)

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21
Q

Oxidase-positive
gram negative bacilli
grows well on highly alkaline selective media (thiosulfate-citrate-bile salts-sucrose TCBS agar)

  1. identify bacteria and shape
  2. what is the mechanism of action of toxin
  3. what is tx?
A
  1. vibrio cholera - comma shaped (curved rod, mobile)
  2. stimulates G protein to activate adenylate cyclase
  3. if no altered mental status, no lethargy, strong pulse = ORAL fluid and electrolyte replacement

if serious sx = IV fluid, electrolytes

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22
Q

non-lactose fermenting, gram-negative rods on MacConkey agar.
bacteria ferments glucose without gas production
do not generate hydrogen sulfide when grown on triple sugar iron agar, cannot replicate at refrigeration temps

identify and its route of pathogenesis

A

shigella - mucosal invasion through Mcells over peyers patches

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23
Q

How are are E. coli and Enterobacter cloacae

  1. similar
  2. different
A
  1. both are gram negative, lactose fermenting

2. only ecoli is indole positive

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24
Q

What are the two most common causes of PID leading to infertility?

A

Neisseria Gonorrhea

Chlamydia trachomatis

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25
Q

What is the abx category of cefuroxime and what is its mechanism of action?

A

second gen cephalosporin, beta-lactam abx

acts against cell wall synthesis

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26
Q

What virus is strongly associated with cervical and anal squamous cell carcinoma? prevalence is increased with HIV infection

A

HPV types 16, 18

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27
Q

What is a common route of Hep A transmission in the US?

A

contaminated water/food

raw or steamed shellfish

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28
Q

Gram negative coccobacilli, associated with dog bite, mouse-like odor

A

Pasteurella multocida

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29
Q

what should you suspect in a patient from south america with achalasia

A

trypanosome cruzi infection

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30
Q

How does C.difficile damage the intestinal mucosa?

what would the colonoscopy biopsy most likely reveal?

A

Toxin A and B both damage cytoskeletal integrity

Colonic bx: inflammatory exudate composed of mucinous debris, fibrin, necrotic epithelial cells, polymorphonuclear cells

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31
Q

What abxs should be used with toxoplasmosis?

A

Pyrimethamine

Sulfadiazine

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32
Q

What should be suspected with a MRI showing ring-enhancing lesions

  1. negative toxoplasmosis
  2. positive EBV
A

primary central nervous system lymphoma (PCNSL)

–abnormal population of B-lymphocytes

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33
Q

How do Shiga-like toxins work?

A

inhibit protein synthesis in human cells (60s subunit)
–leads to intestinal mucosal cell death
=renal epithelial cell toxicity

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34
Q

What is Metronidazole used for?

A

treat anaeroes and parasites:
Giardia lamblia
Entamoeba histolytica, Trichomonas vaginalis.
Bacterial vaginosis (Gardnerella vaginalis)

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35
Q

How can neonatal tetanus be avoided?

A

Maternal Vaccination

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36
Q

What bacteria is a/w axillary lymphadenopathy and scratches from pets

-what is an additional Symptom that can appear

A

Cat-scratch disease: Bartonella henselae

Bacillary angiomatosis - in immunocompromised pts - red, purple papular skin lesions

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37
Q

How do you distinguish EHEC from other Ecoli?

A

Colorless colonies on sorbitol MacConkey (does not ferment sorbitol)

-shiga-like toxin = HUS (anemia, thrombocytopenia, acute renal failure)

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38
Q

identify the disease:
agitation, disorientation, pharyngospasm, photophobia leading to coma and death

what is the receptor that this disease binds to?

A

Rabies encephalitis

acetylcholine receptors

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39
Q

-widened mediastinum on chest xray
-microscopy: shows long chains described as “serpentine” or “medusa head”
what is special about the capsule formed by this agent?

A

bacillus anthracis

-forms capsule with D-glutamate instead of polysaccharide

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40
Q

recent history of viral esophagitis and pneumocystis pneumonia is virtually diagnostic of what infection?

A

HIV

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41
Q

What is this disease and how is it usually contracted?
fever lasting >10 days
severe, retroorbital pain a/w photophobia
pneumonia
increased liver enzymes
thrombocytopenia

A

q fever - coxiella burnetii

through animal waste

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42
Q

What disease and congenital defects are a/w the following symptoms in the mother:
immigrant, low-grade fever, macupapular rash w cephalocaudal progression, posterior auricular and suboccipital lymphadenopathy, eventual polyarthralgia

A

Rubella

sensorineural deafness
cataracts
cardiac malformations (PDA)

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43
Q

What type of virus is Herpes simplex I

A

double stranded, DNA, enveloped

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44
Q

What type of virus is rubella?

A

togavirus

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45
Q

what type of outer covering is a/w gram negative bean-shaped diplococci?

A

Neisseria meningitidis

–Outer membrane Lipooligosaccharide

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46
Q

what two infections are commonly the cause of ectopid pregnancy?

A

Neisseria gonorrhoeae

Chlamydia trachomatis

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47
Q

How does CMV infections present in:

  1. immunocompetent
  2. immunocompromised
A
  1. Mononucleosis-like illness

2. Odynophagia (linear esophageal ulcers), Retinitis

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48
Q

What activity is giardia lamblia infection a/w?

A

drinking contaminated water:

hx of camping, hiking in the mountains, white-water rafting

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49
Q

What secondary infection can form the in the cavitary lesion caused by a prior TB infection of the lung?

A

Aspergilloma colonization

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50
Q

what are the 3D’s of clostridium botulinum infection sx?

A

diplopia
dysphagia
dysphonia

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51
Q

Nikolsky’s sign, epidermal necrolysis, fever, pain a/w skin rash are symptomatic of what?

A

Staphylococcal Scaled Skin Syndrome

exotoxin

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52
Q

What is the use of fidaxomicin and what is the mechanism of action?

A

Clostridium difficile infection

inhibits the sigma subunit of RNA polymerase

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53
Q

A young woman with asymmetric polyarthritis (knee, elbow, wrist)
synovial fluid analysis = neutrophilic predominance and intracellular organisms

what is the cause?

A

Neisseria Gonorrhea

disseminated gonococcal infection (DGI)

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54
Q

What are serum electrolyte findings of a Legionella pneumonia infection?

What is the treatment of Legionnaire’s dz?

A

Hyponatremia

Tx: Fluroquinolones or Macrolides (Azithromycin)

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55
Q

What type of virus is parvovirus?

A

Nonenveloped single stranded DNA virus

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56
Q

What type of presentation can Listeria cause? what abx is used? why?

A

Meningitis in young infants or immunocompromised

-use Ampicillin (because Cephalosporin resistant)

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57
Q

What type of fungi is able to survive intracellularly inside a macrophage and cause systemic symptoms (cough, low-grade fever, hepatosplenomegaly)

A

Histoplasma capsulatum

58
Q

What is the main toxin produced by Clostridium perfringens? what is its mechanism of action?

A

Lecithinase (alpha toxin) - degrades lecithin, destroys cellular phospholipid membranes

59
Q

What diarrhea causing bacteria is a/w ascending muscle weakness and paralysis

what is another dz a/w with the weakness?

A

Campylobacter jejuni is a/w Guillain-Barre Syndrome

also:
Mycoplasma respiratory infections

60
Q

What is the route of infection from outside to meninges of Neisseria Meningitis?

A

Pharynx - blood - choroid plexus - meninges

61
Q

Abdominal pain
bloating, large, bulky stools
Small bowel bx: acid-Schiff-positive macrophages in lamina propria

A

Whipple’s disease (Tropheryma whipplei - gram positive rod)

62
Q

Most common cause of septic arthritis in young person?

A

Gonococcal arthritis - Neisseria Gonorrhea

63
Q

What is the most common Zink compensatory pattern in 80% of patients?

A

OA - rotated left
Thoracic inlet - rotated right
Thoracolumbar - rotated left
Pelvic - rotated right

64
Q

14 year old boy
headache
fever
rash that begins on palms and soles and spreads to trunk
macules and petechiae covering most of body

A

Rocky Mountain Spotted Fever

65
Q

5 year old
rash on hands, cognitively delayed since birth
Biltateral notched incisors, widely spaced
hepatosplenomegaly
ulcerative rash on feet

A

Congenital Syphillis

66
Q

How is an eosin methylene blue (EMB) agar plate interpreted?

A

organisms that ferment lactose (like E coli) produced colonies that have a distinct green metallic sheen

67
Q

What is a classic finding in mononucleosis (EBV) pts?

A

erythematous maculopapular rash that appears after a pat has been given antibiotics (amoxicillin) for presumed bacterial pharyngitis

68
Q

Identify:
parasite - o
triad: periorbital edema, myositis, eosinophilia
preferentially involves muscles of the upper extremities, neck and face

A

Trichinellosis - mostly from ingestion of infected wild game - pigs

69
Q

What are the top two causes of septicemia in sickle cell patients? Why?

A
  1. Strep Pneumo
  2. Haemophilus influenza

-because sickle cell patients eventually become asplenic

70
Q

Motile gram positive rods
produces a narrow zone of B-hemolysis on blood agar
grows well at refrigeration temperature
identify organism and important aspect of immunity for removal

A

Listeria monocytogenes

Cell-mediated immunity

71
Q

Which disease shows an intracellular maltese cross?

What disease is also transmitted by the same organism?

A

Babesiosis

Lyme disease is also transmitted by the Ixodes tick

72
Q

25 year old has a stillbirth at 18 weeks gestations
she reports having pain in knees and feet while being on her feet all day teaching at elementary school

Fetal autopsy - pleural effusion, pulmonary hypoplasia, ascites

what was she infected by?

A

Parvovirus B19

  • school outbreaks
  • symmetric arthralgias
  • fetal hydrops
73
Q

HIV patient
watery diarrhea without fever, weakness
acid-fast pathogen

A

Cryptosporidosis

74
Q 
4 year old complaining of severe anal itching which is worse at night
other children in class has the same

what is dx, what is the diagnostic test? what is the classification of the pathogen? What is tx?

A

Pinworms (Enterobius vermicularis) - cellophane/scotch tape test - reveal eggs

Nematode, dioecious (distinct male and female organisms)

Tx: Albendazole

75
Q

Why does Hepatits D virus need Hepatitis B virus to infect?

A

HDV uses the HBV surface antigen (HBsAg) to replicate its own genetic material

76
Q

15 year old male present with sore throat (2 weeks) + fatigue
oropharynx: erythema, tonsillar exudates, palatal petechiae, splenomegaly, posterior cervical adenopathy
Labs show lymphocytosis

identify pathogen and test?

A

Infection mononucleosis from EBV
–triad: fever, pharyngitis, lymphadenopaty

Heterophile antibody test

77
Q

5 year old present with 3 days of diarrhea, initially water but then became blood-tinged
pt attends kindergarten
mild tachycardia, no fever
Stool: mucous, blood, non-motile bacterium, increase polymorphonuclear cells that grow white colonies on MacConkey agar

Identify pathogen

A

Shigella spp.
white on MacConkeys = lactose NONfermenter
–differs from salmonella because SHIGELLA IS IMMOTILE

78
Q

What part of HIV

  1. helps with fusion and entry into attacked cells
  2. outermost part of protein that attaches to CD4 on T-cells
A
  1. gp41

2. gp120

79
Q

high fever, muffled voice, inspiratory stridor, respiratory distress

identify dz and most common cause

A

Epiglottitis

Haemophilus influenza

80
Q

What is the most common cause of pneumonia in adults and older children with cystic fibrosis?

A

Psuedomonas aeruginosa

81
Q

burn patient with hemorrhagic bullae and sepsis
identify most probably pathogen?

What is the most appropriate pharm therapy?

A

ecthyma gangrenosum = hemorrhagic bullae

pseudomonas aeruginosa

Tx: Piperacillin or Ticarcillin/Tazobactam

82
Q

Pt presents with painful ulcer in lower leg. She was recently in Sudan. upon inspection there is a worm protruding from the center of the ulcer

what is this and what could have prevented this?

A

Dracunculus medinensis - “protruding worm”

Drinking filtered water - dz is acquired through infection by drinking water containing infested fleas, and releases larvae when wound is placed in water

83
Q

Gram negative, question mark shaped spirochete
causes flu-like symptoms, HA, fever, abdominal pain
Jaundice, photophobia

What is the pathogen and how it acquired?

A

Leptospira interrogans - animal urine

84
Q

Which type of hernias occur:
1. Lateral
2. Medial
to the inferior epigastric arteries

A
  1. Indirect - through the deep inguinal ring, external superficial inguinal ring
  2. Direct
85
Q

Which abx should be used to treat Trematode: Clonorchis sinensis?

A

Praziquantel - increases cell membrane permeability

86
Q

28 yr old present with sudden onset of vomiting, diarrhea 6 hours ago. Pt just returned from Carribean cruise vacation last night. denies in blood in vomit or stool. Febrile

Identify pathogen and classification

A

Norovirus

Non-enveloped single stranded RNA virus

87
Q

8 year old present after a seizure. has been severe headaches and high fevers the past two days. Exam shows somnolent child with temp of 104.1. lumbar puncture shows free living ameba.

Identify dz and predisposing factor?

A

Naegleria fowleri = rapidly fatal amebic meningoencephalitis

swimming in freshwater lakes

88
Q

pt returns from trip to Uganda. reports five weeks of fever, headache, itchy hives, and cough that began after swimming in a river. Itching was the “worst itch I’ve ever had”.
Phys exam: inguinal lymphadenopathy, mild hepatosplenomegaly, small eggs in stool

identify pathogen, what is treatment? what is the mechanism of this treatment?

what can this pathogen cause if untreated (in third world countries)

A

Schistosomiasis - treat with Praziquantel

  • -trematode (fluke)
  • -praziquantal increase calcium permeability of the tegument of the worm = paralysis and death

Can lead to Squamous Cell Carcinoma of the Bladder

89
Q

What is the most common cause of prosthetic valve acute endocarditis?

A

Staphylococcus aureus

  • Coagulase-positive
  • B-hemolytic
90
Q

hunter went on a trip with his hunting dogs. after living with his dogs for a week he gets HA and generalized malaise. develops RUQ pain after 3 weeks. Febrile, HTN, Tachycardia, elevated liver fxn tests, lymphopenia
CT of head shows single large locular cyst

identify pathogen and tx?

A

Echinococcus granulosus
-tapeworm transmitted from eggs in dog feces - large, locular cysts found in liver, lungs, brain

Tx = albendazole

91
Q

what dz does the tick Dermacentor andersoni transmit?

A

Colorado tick fever (ds RNA virus)

“saddleback fever”

92
Q

pt (immigrant from Mexico) is brought to ED after a seizure. pt has been more irritable and aggressive than usual for the past week. Pt complains of abdominal pain and constipation. Head CT shows three 1 cm, calcified, spherical hypodensities

identify dz?

A

Cysticercosis = extra-intestinal cyst formation in Taenia solium or Taenia saginata tapeworm infection.

-infection from ingest1ion of cysts that contain larva in undercooked pork or beef.

93
Q

What is the most common cause of nosocomial pneumonia due to use of a respirator

A

Pseudomonas aeruginosa

94
Q

What is the most common pathogen causing croup? what type of pathogen is it?

A

Parainfluenza virus type 1

–enveloped helical Negative-sense ssRNA

95
Q

18 year old present to ED with severe shortness of breath. started yesterday gotten worse over 24 hrs. just returned from a trip to the grand canyon.

Phys exam: interstitial infiltrates, ausculatation = ralles, wheezing.
Pt rapidly worsens.

A

ARDS secondary to HANTAVIRUS infection.

  • -virus found in SW US.
  • -inhalation of contaminated rodent feces in dry air.
  • -typically present with moderate-severe resp symptoms that quickly worsen into ARDS

(severe pulmonary syndrome following flu like symptoms)

96
Q

13 year old boy presents with sore throat, headache, and fatigue. Sx began one week ago. 102 fever, anterior and post cervical lymph nodes are symmetrically enlarged. Enlarged tonsils, erythematous, covered with exudate. elevated WBC, elevated lymphocytes with atypical lymphocytes (large lymphoctes with nucleoli)

what is dz and what is a likely complication?

A

Infectious Mononucleosis (EBV) - dx’d by heterophile Ab test “monospot”
–triad:
1. fever
2 pharyngitis
3. lymphadenopathy
ATYPICAL LYMPHOCYTOSIS (increased large lymphocytes with nucleoli)

Complication: Splenoegaly -> Splenic Rupture (refrain from athletic activity)

97
Q

58 yr old pt presents with severe HA, facial pain, decreased mental status. face as 10/15 cm unilateral cellulitis w black, necrotic centers. hemorrhagic nasal discharge. Serum glucose: 380, bicarb: 5, pH: 7.1.

What is most likely etiology?

A

Rhizopus spp.

  • -rhinocerebral infection w vascular involvement leading to necrotic facial cellulitis, pain, hemorrhagic nasal discharge, ALTERATION in mental status
  • -more common in pts with uncontrolled diabetes mellitus
98
Q

18 year old Hispanic pt presents with fever, joint pain of three week’s duration. He states that his fever seems to rise and fall throughout the day. sweats at night. Generalized joint pain, most pronounced at SI joints. recent hx of returning from mexico where he was working on his uncle’s dairy farm producing goat cheese and unpasteurized milk.

what is dx?

A

Brucellosis - contact w infected goats, sheep, unpasteurized milk

gram-negative aerobic coccobacilli - can invade both phagocytic and nonphagocytic cells - suppress bactericidal responses of the immune system

present: UNDULATING FEVER, joint pain (SI joint), large joints of the lower extremity, profuse sweating

99
Q

What is the deficient enzyme:

15 year old pt with exercise intolerance, myalgias, muscle cramps, myoglobinuria after exercise

A

McArdle’s dz - Muscle phosphorylase

100
Q

What is the deficient enzyme:

newborn Ashkenazi infant with severe hepatomegaly hypoglycemia, hyperlipidemia, lactic acidosis

A

von Gierke’s dz (glycogen storage dz type I)
–Glucose-6-phosphatase

–inability of liver to generate glucose during fasting - glycogen accumuates in the liver = symptoms

101
Q

What is the deficient enzyme:

4 month old w generalized hypotonia, muscle weakness, respiratory distress, failure to thrive. CXR shows cardiomegalyl

A

Pompe’s dz (glycogen storage dz type II)

  • -Alpha 1,4 glucosidase
  • -accumulation of glycogen in tissues such as the skeletal muscle and myocardium = diffuse myopathy - leading to respiratory and cardiac failure
102
Q

Pt presents with rapidly fluctuating fever. night sweats, general malaise. Single erythematous, nontender plaque on his arm and palpable liver 4cm under ribcage.
Elevated ALT, AST. decreased leukocytes, platelets
Bone marrow sample reveals Macrophages with amastigotes
what is dz and what was vector?

A

Leishmania donovani - infection of bone marrow, liver, spleen = pancytopenia
–Spiking fever, hepatomegaly, skin papules or ulcers

transmitted by Sandfly

103
Q

pt w progressive muscle weakness in left leg. fevers/HA began 10 days ago, lasted for 3 days. Lumbar puncture shows elevated pressure, lymphocytosis, elevated protein, normal glucose. She acquired condtion from contaminated water. what is pathogen?

A

Poliomyelitis - picornavirus

–present with febrile illness that leads to focal neurologic deficits

104
Q

What is the location of pathology in a primary tuberculosis infection?

A

Infiltrate in lower lob and adjacent lymphadenopathy

= “Ghon’s complex” in lower lobs

105
Q

Pt presents with rash (ascending lymphangitis) that has been moving up arm. First noticed days after extensive yard work. Culture shows cigar-shaped budding yeast.

What is pathogen? what is treatment?

A

Sporothrix Schenckii - THERMAL DIMORPHIC fungus with cigar shaped yeast

“Rose-gardener’s disease” - begins as small papul at site of invocation (usually hand) then ulcerates

Tx: Itraconazole

106
Q

4 month old presents with watery diarrhea. started loose stools and low fevers 2 days ago. Phys exam shows fever, and tachycardia. bowel sounds are hyperactive and stool guaiac test is negative What is the most likely etiology?

A

Rotavirus - the most common cause of gastroenteritis and diarrhea in young children

107
Q

pt presents w fevers and severe, crushing pain in her face, back, and arms. Pt traveled to S America two weeks ago. macular rash on her chest and abdomen.

What is pathogen?

A

Dengue fever - icosahedral flavivirus (mosquito)

linear single stranded RNA

108
Q

Bioterror associated organism. Pt sustained puncture wound on finger - febrile, chills, new erythematous swelling of right epitrochlear and axillary lymph nodes. Sharply demarcated ulceration of third finger of right hand with yellow exudate. Cultures show Gram negative coccobacillus gorwin in cysteine-glucose-blood agar

what is pathogen?

A

Francisella tularensis

  • -ulceration w fevers, chills, lymphadenopathy
  • –aerobic, gram neg bacillus, grows on cystein-glucose-blood agar

–only 5 bacteria needed to cause infection

–ulceration w yellow exudate

109
Q

5 year old presents with fever, painful skin rash on arms and trunk. skin is erythematous w large blisters and serous fluid that contains organims. There is splitting of the epidermis at the stratum granulosum

what is most likely agent?

A

Staph aureus. - Bullous impetigo caused by exfoliative toxin

–if blisters had NO organisms - could possibly be Scalded-skin syndrome - from toxin

110
Q

66 yr old pt present with abdominal pain, foul-smelling diarrhea, joint pain, weight loss for the past few months. Recently shown confusion. Exam shows adenopathy with abdominal distention. Sent home with abx that cover gram positive bacteria

what is pathogen and etiology?

A

Tropheryma Whippleii - Macrophages that phagocytose the organism compress the lacteals preventing absorption of chylomicrons

-SYSTEMIC dz - abd pain, diarrhea, arthralgias, neuro, cardiac problems, lymphadenopathy

Tx: doxycycline, macrolides

111
Q

24 yr old woman presents with seizure. complained of fever, HA earlier in the morning. exhibited tonic-clonic symptoms shortly after. No longer convulsing, but emetic and confused. MRI shows left temporal lobe hemorrhage. CSF shows viral cause

what is pathogen?

A

Herpes simplex virus 1

112
Q

19 year old presents w diarrrhea, abdominal cramping, progressive diarrhea with subjective fevers. Bloody diarrhea develops. Stool eval shows trophozoites w ingested erythrocytes

what is pathogen and tx?

A

Entamoeba histolytica
–amoebic dysentery (bloody diarrhea, fever, abdominal pain)

Tx: Metronidazole

113
Q

Identify dz:
14 yr old male w lower abdominal pain, fever 5 days ago. painful swellings on posterior cheecks
Testicular swelling and tenderness.

A

Mumps

114
Q

Identify pathogen:
8 year old w temp of 103.9. Complains of chills and irritable
Sustained a bite from pet cat on wrist 3 days ago. Notable erythema, edema, decreased range of motion in wrist

A

Pasteurella multocita - gram negative facultative anaerobic bacterium
—–causes Cellulitis, Osteomyelitis following bites from domesticated animals

(distinguish from Bartonella henselae “cat scratch” = regional lymphadenopathy, scratch, papule, fever, backache)

115
Q

What are 3 factors that make pseudomonas lethal?

A
  1. Pyocyanin - blue-green pigment
  2. endotoxin
  3. EXOTOXIN A - inactivates elongation factor 2 (EF-2)
    - –EF-2 in liver = inhibits protein synthesis and kills cells
116
Q

identify pathogen:
19 yr old pt has rash. his sexual partner has similar rash on genitals and inner thich. 2-3 dome-shaped papules with a central umbilication on the penis and inner thigh

A

Poxvirus - Molluscum contagiosum

117
Q

What is the therapy for duodenal ulcers from an H. pylori infection?

A

Triple Therapy:

Amoxicillin, Clarithromycin, + a proton pump inhibitor

118
Q

18 year old w fever, headache, nausea, chills, vomiting. Petechial purpuric rash on legs. Nuchal rigidity. CSF: high protein, low glucose

what is pathogen?

A

Neisseria meningitidis
–meningitis with petechial/purpuric rash

(strep pneumo is most common cause of meningitis in children from 3mo-9years, and adults 19 years and older)

119
Q

Older pts infected with influenza are at higher risk for a superinfection from what? what is the classic sign for this?

A

Streptococcus pneumoniae

-look for “double sickening” = pts started to get better then bein to experience fevers and worsening symptoms

120
Q

AIDS pt presents with mental status changes, weakness, blurry vision. CSF is diagnostic for infection causing progressive multifocal leukoencephalopathy.

what is pathogen? how prevalent is it?

A

JC virus - causes progressive multifocal leukoencephalopathy (PML)

–widespread in the population, disease only seen in immunocompromised

121
Q

Identify pathogen and shape/classification:

fevers, chills, cellulitis wit bullae on hands of saltwater fisherman who recently handled shellfish

A

Vibrio vulnificus
-Gram negative, Motile
Curved Rod

122
Q

HA, fever, myalgia, macular erythematous rash on chest

no cough, nausea, vomiting, diarrhea

positive WEIL-FELIX
transmitted by Body Louse

what is pathogen?

A

Rickettsia prowazekii

  • -Endemic Typhus
  • —-flu like Sx w truncal rash
123
Q

HIV pt w productive cough, fevers, chills, night sweats, myalgias. inspirator crackles in right lower lob. Sputum analysis reveals a filamentous, partially acid-fast, gram positive

what is pathogen?

A

Nocardia asteroides

  • -gram positive
  • -aerobic
  • -weakly acid-fast
  • -filamentous bacterium (branching filaments)

–known for causing pulmonary infection in immunocompromised individuals

124
Q

What is the virulence factor of Mycoplasma pneumonia that allows it to evade immune response?

what is the dx stain?
how is it cultured?

A

P1 protein - serves as adhesin and allows the bacteria to adhere to the respiratory mucosa

doesnt have cell wall - so cannot be stained

grows on EATON’s AGAR

125
Q

What are three most common causes of Otitis media?

what is the management?

A
  1. S. pneumoniae
  2. H. influenzae
  3. M. catarrhalis

Tx: Oral Amoxicillin

126
Q

What is the initial drug of choice for malaria?

A

Chloroquine

127
Q

What is the use of Primaquine (specific)

A

added to regiment if pt is infected w
P. vivax or P. ovale

-for Latent hepatic schizonts
PREVENTS FUTURE RELAPSES

128
Q

Which type of malaria is considered a medical emergency?

A

Plasmodium falciparum

129
Q

2 year old w fever, stiff neck after an upper respirator infection. Lumbar puncture shows gram-positive cocci

what is the most appropriate pharm management

A

Vancomycin

bacterial meningitis children: S. pneumo, N. menin, H. influ

gram + CSF = S. pneumo = use vancomycin

130
Q

Identify dz:

Mexican immigrant w fatigue, weight loss, night sweats, chronic back pain. Febrile, MRI shows Vertebral lesion

A

Pott disease - vertebral osteomyelitis caused by Mycobacterium tuberculosis

131
Q

Aids pt w fatigue and fever. Bone marrow bx reveals granulomas and a culture that grows budding yeast at 37C (98.6F) and a mold with hyphae at 25C (77F).

identify pathogen

A

Histoplasma capsulatum

  • –dimorphic as:
    1. mold in colder temps
    2. intracellular yeast at body temp

inhaled from environment from bird/bat droppings
–infects alveolar macrophages

132
Q

What is the treatment for Lyme disease (borrelia bugdorferi, spirochete)?

  1. for children under 8
  2. for adults
A
  1. Amoxicillin

2. doxycycline - contraindicated in children under 8 because of severe side fx of the bones and teeth

133
Q

pt w abrupt onset of fever, chills, malaise, sever HA, two days sever nausea, vomiting, diarrhea. Recently returned from W Africa. Febrile, hypotensive, tachycardic. Diffuse erythematous, nonpruritis maculopapular rash on her face and neck. Fecal occult blood test is positive

what is the pathogen? what is the classification

A

Filoviridae (Ebola and Marburg Viruses)

–Non segmented negative sense RNA genome

134
Q

48 year old recently returned from trip to SE Asia w exquisitely tender and enlarged palpable lymph node w associated fever, chills, general weakness. Painful area of swelling surrounded by dark hemorrhagic purpura on the left leg where pt was bitten by a flea

what is dz?

A

Yersinia pestis - bubonic plague

135
Q

What are the treatments/mechanisms for cryptococcus neoformans meningitis/encephalitis?

A

Amphotericin
—increases membrane permeability by binding to erosterol in the plasma membrane

or Flucytosine - converted to 5-FU - intereferes w DNA synthesis

136
Q

How can Strongyloides stercoralis infection be prevented?

A

Wearing appropriate footwear

137
Q

What is the first line treatment for:

  1. gonorrhea
  2. chlamydia
A
  1. Ceftriaxone

2. Azithromycin or doxycycline

138
Q

what is the most important virulence factor of gram positive cocci, catalase negative, clear hemolysis, bacitracin sensitivity that causes

  1. skin infection
  2. fever with rash
A

S. pyogenes - M protein

  1. cellulitis - M PROTEIN
  2. Scarlet fever - ERYTHROGENIC EXOTOXIN
139
Q

What is the capsid structure and genomic content of Coxsackie A virus?

A

naked icosahedral capsid, single-stranded RNA

140
Q

pt w watery, blood tinged diarrhea and fever of 3 days. recently returned from camping trip in mexico. Stool has RBC, WBC, cultures show organism ferments sorbitol. 10 days later Sx resolve w/o abx

identify pathogen

A

Enteroinvase Escherichia coli

141
Q

Pt w fever, cough, chest pain, nausea, myalgias that works in textile factory

what is pathogen
what are 3 abx to use?

A

Bacillus Antracis

Penicillin
Doxycycline
Ciprofloxacin

142
Q

5 yr of w severe watery diarrhea for 3 days. dehydrated, no signs of blood in stool. other children at school have the same problem

what id the pathogen? what is the shape/classification of the pathogen?

A

Rotavirus
-Double stranded segmented RNA virus

most common cause of severe non-bloody diarrhea in children under 5

COMLEX STEP 1 2017 (19 decks)

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