Microbio

Question 1

What is the pathogenic mechanism for Shigella infection

Answer 1

Mucosal invasion of M cells

Question 2

Three vulnerable populations for Shigella

Answer 2

Kids
men who have sex with men
adults in nursing facilities

Question 3

The host inflammatory response against Shigella is largely mediated by

Answer 3

Neutrophils

Question 4

What best explains lack of protective immunity agaiinst Neisseiria infections?

Answer 4

High variability of microbial surface antigenic structure

Question 5

The Hib vaccine protects against

Answer 5

Encapsulated Haemophilus influenza meningitis

Question 6

Non-encapsulated H influenzae cause

Answer 6

otitis media, sinusitis and bronchitis in little children

Question 7

which part of the US is Blastomyces dermatitidis found?

Answer 7

Mississippi and Ohio River valleys

Question 8

Symptoms of Blastomyces infection in immunocompetent

Answer 8

granuloma formation, mimics pneumonia

Question 9

Mucor species is characteristic of patients with

Answer 9

neutropenia, burns or diabetes mellitus (diabetic ketoacidosis)

Question 10

Risk factors for pneumocystis jirovecii infection in HIV pt

Answer 10

CD4 <200; oropharyngeal candidiasis

Question 11

Prophylaxis for pneumocystitis jirovecii infection in HIV pt

Answer 11

Trimethoprim-sulfamethoxazole

Question 12

Risk factors for Toxoplasma gondii infection in HIV pts

Answer 12

CD4 <100

Positive Toxoplasma IG antibody

Question 13

Prophylaxis for Toxoplasma gondii in HIV pts

Answer 13

Trimethoprim-sulfamethoxazole

Question 14

Risk factor for Mycobacterium avium infection in HIV pt

Answer 14

CD4 <50

Question 15

Prophylaxis against Mycobacterium avium in HIV pt

Answer 15

Azithromycin

Question 16

Risk factor for Histoplasma capsulatum infection in HIV pts

Answer 16

CD4 <150

Ohio and Mississippi river valley

Question 17

Prophylaxis for Histoplasma infection in HIV pts

Answer 17

Itraconazole

Question 18

How to distinguish TB infection from Mycoplasma avium complex infection in HIV patient?

Answer 18

MAC more likely presents with reticuloendothelial symptoms like hepatosplenomegaly, elevated alkaline phosphatase and LDH and anemia; grows best at 41C

Question 19

What is the major virulence factor for Haemohphilus influenzae type b?

Answer 19

Polyribosylribitol phosphate (PRP) capsule that binds H1 and prevents complement deposition

Question 20

How does diphtheria exotoxin function

Answer 20

Inhibits protein synthesis by ADP-ribosylation (inhibition) of intracellular EF-2

Question 21

what does Diphtheria toxin cause morphologically

Answer 21

Respiratory cell necrosis with formation of fibrinous, coagulative exudates

Question 22

Degradation of lecithin by lecithinase is a function of which pathogen

Answer 22

C. perfringens (causes gas gangrene)

Question 23

Shiga toxin (Shigella) and Shiga-like toxin (EHEC) causes protein synthesis inhibition by

Answer 23

inactivation of 60s ribosomal subunit

Question 24

How does pertussis AB exotoxin function

Answer 24

Catalyzes ribosylation of G protein alpha1 subunits leading to increased cAMP production.

Question 25

Consequences of Pertussis exotoxiin

Answer 25

Increased insulin production, lymphocyte and neutrophil dysfunction and increased sensitivity to histamine

Question 26

Example of a selective medium

Answer 26

Thayer-Martin VCN (identify Neisseiria species and fungi)

Question 27

Example of differential media

Answer 27

MacConkey agar and Eosin methylene blue to culture enteric organisms (ferment lactose- pink on M, black on E)

Question 28

Example and purpose of reducing media

Answer 28

Thioglycolate broth, culture anaeorbic organisms

Question 29

What is the major virulence factor for Strep pyogenes

Answer 29

Protein M; inhibits phagocytosis and activation of complement

Question 30

Most common cause of retinitis in HIV-positive patients

Answer 30

CMV

Question 31

Treatment for CMV retinitis

Answer 31

Gancliclovir (guanine nucleoside analog with greater activity against CMV DNA polymerase)

Question 32

Clarithromycin treatment for HIV patients

Answer 32

Mycobacterium avium complex

Question 33

Flucytocine treats

Answer 33

Fungal infections including cryptococcal infections

Question 34

Treats hepatitis B and C, hairy cell leukemia, condyloma acuminatum and Kaposi's sarcoma

Answer 34

Leukocyte interferon alpha

Question 35

Treats pneumocystis pneumonia

Answer 35

Pentamidine

Question 36

Which cells play a key role in Myocobacterium tuberculosis infection?

Answer 36

CD4+ T cells, which recruit macrophages that form Langhans giant cells (have multple nuclei organized in shape of horseshoe)

Question 37

Acute treatment of Corynebacterium diptheriae

Answer 37

1. Diptheria antitoxin (passive immunization) 2. Penicillin or erythromycin 3. DPT vaccine

Question 38

The clinical consequence of C. diptheria are due to

Answer 38

Exotoxin

Question 39

S. Aureus uses this enzyme to activate prothrombin, convert fibrinogen to fibrin and protect itself against phagocytosis

Answer 39

Coagulase

Question 40

Lecithinase (alpha toxin) is the major virulence factor for which pathogen

Answer 40

C. perfringens

Question 41

Has phospholipase C activity that increases platelet aggregation and adherence molecule expression on leukocytes and endothelial cells, causing vasocclusion and necrosis of affected tissues

Answer 41

Lecithinase (alpha toxin) of C. perfringens

Question 42

Oral thrush, interstitial pneumonia and severe lymphopenia in first year of life suggests

Answer 42

Vertical transmission of HIV from mother to child

Question 43

Treatment for HIV pregnant woman to avoid vertical transmission

Answer 43

2 Reverse transcriptase inhibitors + protease inhibitor/non-nucleoside RT inhibitor, or integrase inhibitor

Question 44

Which anti-HIV therapy is teratogenic?

Answer 44

Efavirenz in first 8 weeks

Question 45

Zidovudine usage in infants is for

Answer 45

HIV prophylaxis if they were born to HIV-infected mothers

Question 46

NRTI therapy that is associated with hypersensitivity reaction in individuals with HLA-B*57:01 allele

Answer 46

Abacavir

Question 47

NNRTIs associated with Stevens-Johnson syndrome and toxic epidermal necrolysis and abnormal LFTs

Answer 47

Efavirenz and Nevirapine

Question 48

NRTI associated with asymptomatic macular rash on palms or soles

Answer 48

Emtricitabine

Question 49

HIV therapy that causes hyperglycemia, GI symptoms and lipodystrophy

Answer 49

Protease inhibitors (lopinavir)

Question 50

White patches on retina in patient with pneumocystis pneumonia implies

Answer 50

CMV retinitis (pts with CD4 <50)

Question 51

Standard tx for Chlamydia

Answer 51

Macrolide (azithromycin-- protein synthesis inhibitor) and Cephalosporin

Question 52

Why is probenecid co-administered with Penicillin in treatment of neurosyphillis or gonorrhea?

Answer 52

Inhibits organic ion transporters in kidney and renal tubular secretion of Penicillin-- Increases penicillin serum concentration

Question 53

Function of M protein on Streptococcus bacteria

Answer 53

Prevents opsonization and destruction by complement

Question 54

Function of Protein A in Staph Aureus

Answer 54

Binds Fc of immunogloblulins to prevent opsonization