Microbe

Question 1

Marker of nitrate reductase–…..

Answer 1

producing bacteria (eg, Escherichia coli, Klebsiella, Proteus mirabilis)

Question 2

Malassezia species yeasts, and the infection is confined to the ……of the skin. It is common in areas with hot and humid climates and is often most visible after extensive….. of the adjacent skin

Answer 2

stratum corneum

sun exposure due to tanning

Question 3

The diagnosis of pityriasis versicolor is made by….. preparation of skin scrapings. Malassezia forms spores and hyphae, producing the characteristic “…….” appearance on light microscopy. The hyphae have a short, “cigar-butt” appearance. This condition is treated with topical antifungal agents or…….

Answer 3

potassium hydroxide (KOH)

spaghetti and meatballs

selenium-containing shampoo

Question 4

Serologic testing (latex agglutination) is used to detect…. capsular antigen in CSF

Answer 4

the C neoformans

Question 5

Previous streptococcal infection is evidenced by elevated streptococcal antibodies like:….

Answer 5

anti-streptolysin,
anti-DNaseB, and
anti-hyaluronidase

Question 6

Anti-HBs is a neutralizing antibody that…..

Answer 6

prevents viral entry into cells…

Question 7

Cryptococcal meningoencephalitis is typically seen in patients with….(count4)

Answer 7

HIV, sarcoidosis, or leukemia and in those on high-dose corticosteroid therapy

Question 8

Histoplasma capsulatum replicates within ….

Answer 8

phagosome of macrophages

Question 9

Risk for neonatal tetanus is reduced substantially by….. and….

Answer 9

hygienic umbilical cord care

vaccination of the mother during pregnancy

Question 10

Shiga toxin–producing Escherichia coli O157:H7 elaborates Shiga toxin, which………….. in colonic mucosal cells, leading to the inhibition of protein synthesis and apoptosis

Answer 10

inactivates 60S ribosomal subunits

Question 11

B anthracis spores germinate at tissue temperatures into vegetative rods that have 2 main virulence factors:

A polypeptide capsule composed of……, which inhibits phagocytosis
A…… composed of protective antigen, edema factor, and lethal factor
Protective antigen binds to a……… on macrophages and forms a channel that delivers lethal factor and edema factor into the cell. Lethal factor is a……….., leading to cell death. Edema factor is a …….that increases cyclic AMP concentration, leading to accumulation of fluid within/between cells and suppression of neutrophil and macrophage function.

Answer 11

poly-γ-D-glutamic acid

trimeric exotoxin

host cell membrane receptor

zinc metalloproteinase that inhibits MAP kinase signal transduction

calmodulin-dependent adenylate cyclase

Question 12

The mechanism of action of edema factor in anthracis is very similar to that of the adenylate cyclase toxin produced by……..

Answer 12

Bordetella pertussis

Question 13

influenza is prone to antigenic changes in its surface glycoproteins due to:

Answer 13

Poor proofreading of viral RNA-dependent RNA polymerase, which results in the introduction of genetic mutations during replication (antigenic drift).
Reassortment of the segmented genome when 2 influenza viruses infect the same cell, which results in dramatic alterations to the genome (antigenic shift).

Question 14

Aspergillus has a predilection for blood vessels and can spread……., causing infection and infarcts involving the…..,……,….., endocardium, and brain

Answer 14

hematogenously

skin

paranasal sinuses

kidneys

Question 15

Chagas disease is caused by a chronic infection by Trypanosoma cruzi and causes secondary….. due to destruction of the submucosal (Meissner) and myenteric (Auerbach) plexus. Other manifestations can include… and……

Answer 15

achalasia

nonischemic cardiomyopathy

megacolon

Question 16

Haemophilus influenzae is a gram-negative coccobacillus that requires both….. to grow. H influenzae type b has an ….which allows it to spread hematogenously and cause invasive disease such as septic arthritis and meningitis.

Answer 16

X factor (hematin) and V factor (NAD+)

antiphagocytic polysaccharide capsule,

Question 17

Primary tuberculosis infection is marked by initial…… within the alveolar space and alveolar….. After a few weeks, CD4 lymphocytes are stimulated to release interferon-gamma, which activates macrophages and allows them to destroy the mycobacteria.

Answer 17

unchecked Mycobacterium tuberculosis replication

macrophages

Question 18

Parvovirus B19 replicates in……

Alteration of….. can allow overgrowth of pathogenic strains of Clostridioides difficile, which produce enterotoxin (toxin A) and cytotoxin (toxin B). Clinical disease can range from transient diarrhea to severe pseudomembranous colitis.

Answer 18

erythrocyte precursors in the bone marrow.

the normal intestinal microbial flora (eg, antibiotic therapy, gastric acid suppression)

Question 19

Erythema infectiosum (fifth disease) is caused by….. and presents with a nonspecific prodrome (eg, malaise, fever, congestion) followed by a classic…. and a lacy, reticular body rash. Parvovirus is highly tropic for erythroid precursor cells and replicates predominantly in the…..

Answer 19

parvovirus B19

“slapped-cheek” facial rash

bone marrow

Question 20

Guillain-Barré syndrome represents a group of immune-mediated polyneuropathies that are thought to be caused by.…….l, leading to demyelination of the……. nerves. Up to one-third of GBS cases are preceded by a………, which is a common cause of acute diarrheal illness.

Answer 20

molecular mimicry

peripheral

Campylobacter jejuni infection

Question 21

Vibrio cholerae must survive the……. environment

Answer 21

acidic

Question 22

The aminoglycoside streptomycin inhibits…….
Decreased activity of bacterial catalase-peroxidase is a mechanism of mycobacterial resistance to…….
Structural alteration of enzymes involved in RNA synthesis (DNA-dependent RNA polymerase) is the mechanism through which organisms become resistant to….

Answer 22

protein synthesis by inactivating the 30S (small) ribosomal subunit.

isoniazid

rifampin

Question 23

Yersinia pestis, the cause of bubonic plague, is transmitted primarily by rodent fleas. Manifestations include rapid-onset systemic symptoms (eg, high fever, chills, weakness, headache) and painful, purulent regional lymphadenitis. First-line treatment is……

Answer 23

aminoglycosides