Block 4

Question 1

Is vancomycin bacteriostatic or bacteriocidal?

Answer 1

bacteriostatic

Question 2

Is fidaxomicin bacteriostatic or bacteriocidal?

Answer 2

bacteriocidal

also used for C diff, has minimal systemic absorption

Question 3

a replication-defective RNA virus that is only capable of causing infection when encapsulated with HBsAg

Answer 3

delta agent aka hepatitis D virus

Question 4

what would happen to Hep D if we were hypothetically able to universally vaccinate everyone with recombinant HBsAg?

Answer 4

Hep D would almost entirely disappear

Question 5

dimorphic fungus that causes a subcutaneous mycosis, often transmitted by a thorn prick

Answer 5

Sporothrix schenkii

Question 6

do cephalosporins (cefepime, ceftrazidime) cover pseudomonas?

Answer 6

yes, they have good antipseudomonal coverage

Question 7

what infections are asplenic patients prone to?

Answer 7

Strep pneumo, H. influenzae, N meningitidis

encapsulated organisms

Question 8

what becomes a problem for pts who experienced splenic rupture secondary to trauma?

Answer 8

systemic bacterial clearance

Question 9

With Rubella, what sequelae do most women develop?

Answer 9

polyarthritis and polyarthralgia

Question 10

what does a fetal infection with rubella cause (during the first trimester)?

Answer 10

deafness, cataracts, and cardiac malformations like a PDA

Question 11

this fungus can be colonizing (‘fungus balls”) and allergic (ABPA) — causing wheezing, fever, migratory pulmonary infiltrates in patients with asthma

Answer 11

aspergillus fumigatus

Question 12

what does inoculation of Candida albicans into serum at 37 degrees C for 3 hours lead to?

Answer 12

formation of true hyphae from the yeast, called “germ tubes”

Question 13

what does Chlamydia A-C cause?

Answer 13

ocular infection (trachoma) in children

Question 14

what does Chlamydia D-K cause?

Answer 14

urogenital (STI) and inclusion conjunctivitis

Question 15

what does Chlamydia L1-L3 cause?

Answer 15

lymphogranuloma venereum (LGV)

chronic = initial painless small ulcer on genital mucosa

weeks later = swollen painful inguinal nodes that coalesce, ulcerate, and rupture (buboes)

Question 16

what do lymphogranuloma venereum lesions contain histologically?

Answer 16

areas of mixed granulomatous and neutrophilic inflammation with chlamydial inclusion bodies seen in the epithelial and inflammatory cells

Question 17

What does the CDC recommend to decrease incidence of congenital rubella?

Answer 17

vaccination of children and non-pregnant females of child bearing age with live-attenuated rubella virus vaccine

Question 18

what non-enveloped, ssDNA virus causes aplastic crisis in sickle cell patients because it infects erythroid precursor cells in the bone marrow?

Answer 18

Parvovirus B19

Question 19

virulence factor found in the peptidoglycan cell wall of Staph aureus that binds to the Fc portion of IgG, leading to impaired complement activation, opsonization, and phagocytosis

Answer 19

protein A

Question 20

Multiple ring-enhancing lesions in an HIV patient indicates…

Answer 20

toxoplasmosis

Question 21

capsular material from 23 serotypes

polysaccharides alone can’t be presented to T-cells, so this induces a relatively T-cell independent B-cell response that is less effective in young children and elderly

Answer 21

PPSV23 vaccine for Strep pneumo

Question 22

contains capsular polysaccharides from 13 serotypes that have been covalently attached to recombinant, inactivated diptheria toxin

induces an active immunity via a T-cell-_dependent_ B-cell response, resulting in improved immunogenicity due to formation of higher affinity antibodies and memory cells

Answer 22

PCV13 vaccine for Strep pneumo

Question 23

What are the treatments for Diphtheria infection?

Answer 23

• Diphtheria antitoxin (passive immunization - most important and has greateast effect on prognosis)
• antibiotics
• active immunization

Question 24

describe why immunity to nontypable strains of H influenzae is not conferred by vaccination w/ Hib vaccine

Answer 24

nontypable strains of H influenzae do not form an antiphagocytic capsule. they are part of the normal flora of the upper respiratory tract

they can cause otitis media, sinusitis, and bronchitis

capsular strains other than type b are also not covered by vaccine

Question 25

what does a naked RNA molecule need to induce viral protein synthesis in a host cell and how does this affect infectivity?

Answer 25

it must be able to act directly as mRNA using the host’s intracellular machinery for translation

naked viruses containing +ssRNA can be infection

naked viruses containing -ssRNA or -dsRNA are NOT infectious

Question 26

what do the symptoms of rheumatic fever result from?

Answer 26

structural homology between antigenic determinants (epitopes) on GAS and on human, cardiac, CNS and cutaneous tissue

Question 27

what disease should be suspected in pts with recent exposure to contaminated water (cruise ships, spas, hospitals, or air-conditioned hotels)?

Answer 27

Legionnaire’s disease

Question 28

What is the most common lab abnormality seen with Legionella, and what would a sputum gram stain show?

Answer 28

lab abnormality = hyponatremia

sputum gram stain often shows many neutrophils but few or no organisms

Question 29

What do ether and other organic solvents do to viruses?

Answer 29

they dissolve the lipid bilayer that makes up the outer viral envelope

loss of infectivity after exposure to these solvents is a characteristic feature of enveloped viruses

Question 30

what are Koplik spots?

Answer 30

small, whitish, bluish, graish specks on buccal mucosa adjacent to the second molars, “grans of sand” on an erythematous base

classical clinical manifestation of measles

Question 31

What does CCCK stand for in measles?

Answer 31

cough, coryza, conjunctivitis, Koplik spots

Question 32

What are the main bacteria that cause necrotizing fasciitis?

Answer 32

* Strep pyogenes

* Staph aureus

* Clostridium perfringens

• Strep agalactiae
• Aeromonas hydrophila

Question 33

Which bacteria is gram positive, coagulase negative, catalase negative, and pyrrolidonyl arylamidase (PYR) positive?

Answer 33

Strep pyogenes

Question 34

what test is positive when horse RBCs are agglutinated in vitro by heterophil antibodies?

Answer 34

Monospot test

Question 35

Describe the type of diarrhea that Vibrio cholerae and enterotoxigenic E. coli cause

Answer 35

Purely a toxin-mediated watery diarrhea

Do not cause cell death, simply modify electrolyte handling

Therefore, no erythrocytes or leukocytes are noted on stool microscopy