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BT_Step1_NTK > STEP1_Microbiology > Flashcards

STEP1_Microbiology Flashcards

1
Q

Streptococcus pneumoniae differs from other bacteria in that it produces α-hemolysis, resulting in __________ in blood agar.

A

green halos

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2
Q

What bug produces IgA protease enzymes that cleave secretory IgA antibodies?

A

S. pneumoniae

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3
Q

List the bacteria that secrete IgA proteases?

A
  • Neisseria meningitidis,
  • N. gonorrhoeae
  • H. influenzae
  • Strep. pneumoniae
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4
Q

What virus has the following characteristics?

localized infections consistening of non-erythematous, pearly, dome-shaped papules on skin. Mainly in peds and immunocompromised Pt. Self-limiting.

A

Poxvirus; which causes Molluscum contagiosum

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5
Q

What are the two most common causes of bacterial meningitidis in young adults?

A

S. Pneumoniae & N. meningitidis

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6
Q

_____________________ is an aerobic, gram-Positive, oxidase-Positive bacteria the produces pyocyanin –> making look blue-green in color.

A

Pseudomonas aeruginosa

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7
Q

What is the MOA of the main virulence factor of Pseudomonas?

A

Endotoxin A;

ADP ribosylates and inhibits elongation factor 2 in host cells –> inhibiting protein synthesis.

(this is similar to Diphtheria toxin)

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8
Q

A medium made of charcoal yest extract with increased levels of iron and cysteine are best used to culture what bacteria?

A

Legionella pneumonphila

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9
Q

Chocolate agar with factor V and X is used to culture what bacteria?

A

H. influenzae

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10
Q

What medium is needed to best culture Corynebacterium diphtheriae?

A

Loffler’s medium

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11
Q

Thayer-Martin medium is used to culture what bacteria?

A

Neisseria gonorrhoeae

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12
Q

What bacteria shows up as black colonies on cystine-tellurite agar?

A

Corynebacterium diphtheriae.

Uses exotoxins that inhibits protein synthesis via ADP-ribosylation of EF-2

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13
Q

Is S. agalactiae bacitracin resistant?!

A

YES!

the other bugs that are Group A are not!

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14
Q

What is the most common cause of neonatal meningitis?

A

Group S Strep (GBS).

S. agalactiae is beta-hemolytic, gram-positive coccus found in chains.

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15
Q

Clostridium tetani is a spore-forming, gram-positive bacillus that is transmitted through contaminated soil/feces, whose entrance into the body is often facilitated by puncture wounds from sharp objects like nails. It produces an exotoxin that blocks ____1____ and ____2____ from inhibiting muscular contractions, resulting in tonic contraction (tetanus).

A
  1. glycine

2. GABA

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16
Q

____________ infection, which presents with a painless ulcer with a beefy red base and irregular borders

A

Klebsiella granulomatis

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17
Q

The chancre from T. pallidum infection is noted to having what features?

A

painless, non-exudative, clean, hard base with indurated margins (“punched out base with rolled edges”)

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18
Q

What bugs causes an infection, described as a deep, undermined, painful purulent ulcer with soft ragged edges.

A

Hemophilus ducreyi

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19
Q

_____________ is mainly found in tropical areas and causes yaws, which manifest as destructive lesions of skin and bones.

A

Treponema pertenue

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20
Q

How do gumma present on the skin?

A

Ulcers or granulomatous lesions with round, irregular shape.

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21
Q

Treponema pallidum is a ____1____ spirochete that causes ____2____.

A
  1. microaerophilic
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22
Q

What are the defining characteristics of each stage of syphilis?

A

1st stage: painless chancre

2nd stage: painless rash on the palms of the hands and soles of the feet.

3rd stage: neurosyphilis (demyelination of the posterior column), gumma formation, and aortitis. The aortitis can result in an aortic aneurysm.

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23
Q

Haemophilus ducreyi is a small, pleomorphic, gram-____1____ that causes ____2____, an ulcerative genital lesion.

A
  1. negative bacilli

2. chancroid

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24
Q

What pathogen grows in short parallel chains, sometimes referred to as “school of fish” in appearance under microscopy.

A

H. ducreyi

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25
Q

What pathogen is the causative agent of granuloma inguinale (donovanosis), an ulcerative genital lesion.

A

Klebsiella granulomatis;

Gram-negative, rod-shaped bacterium

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26
Q

Acyclovir, famciclovir, and valacyclovir are _______ analogs used to treat active HSV and VZV (not latent forms).

A

guanosine

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27
Q

__________ is also a guanosine analogue but has limited efficacy against CMV

A

Acyclovir

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28
Q

Acyclovir, famciclovir, and valacyclovir are _________ analogs.

A

guanosine

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29
Q

A gumma is a soft, non-cancerous granuloma that typifies tertiary syphilis. Histological features include what?

A

a central region of coagulative necrosis, palisading macrophages, multinucleated giant cells, fibroblasts, lymphocytes, and plasma cells. The causative organism, Treponema pallidum, is only rarely found.

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30
Q

What bacteria are poorly Gram stain and can be remembered by the mnemonic “These Microbes May Lack Real Color”?

A
  • Treponema
  • Mycobacteria
  • Mycoplasma
  • Legionella pneumophila
  • Rickettsia
  • Chlamydia
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31
Q

Why does Treponema poorly gram stain?

A

Treponema are too thin to be visualized and can be visualized by dark-field microscopy and fluorescent antibody staining.

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32
Q

Why Mycobacteria does poorly gram stain?

A

Mycobacteria have a high lipid content and mycolic acids in cell wall can be detected by carbolfuchsin in acid fast stain.

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33
Q

Why does Mycoplasma poorly gram stain?

A

Mycoplasma has no cell wall.

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34
Q

Why does Legionella poorly gram stain?

A

Legionella pneumophila are primarily intracellular and can be visualized via silver stain.

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35
Q

Why does Rickettsia poorly gram stain?

A

Rickettsia are intracellular parasites.

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36
Q

Why does Chlamydia poorly gram stain?

A

Chlamydia are intracellular parasites that lack classic peptidoglycan because of low muramic acid.

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37
Q

Aztreonam is synergistic with what other antibiotic?

A

Aminoglycosides

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38
Q

Staphylococcus epidermidis/saprophyticus are coagulase-____________

A

negative

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39
Q

Aminopenicillins are positively-charged R-groups, extended spectrum ABX. What bugs do they Tx? (8)

A
  • H. flu
  • F. Pylori
  • E. coli
  • Listeria
  • Proteus
  • Salmoanella
  • Shigella
  • Enterococci
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40
Q

Which strep is optochin sensitive? or resistant?

A

S. pneumoniae is optochin sensitive.

S. viridens is optochin resistent

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41
Q

________ is an aminoglycoside that can be applied topically. the other aminoglycosides are parenteral (IV)

A

Neomycin

42
Q

Despite their “-mycin” suffix, what antibiotics are not aminoglycosides?

A
  • Macrolides such as erythromycin, clarithromycin, and azithromycin
  • Lincosamides such as clindamycin and lincomycin
  • Streptogramins such as pristinamycin
  • Vancomycin
  • Daptomycin
43
Q

What type of vaccine is the vaccine for Smallpox?

A

Live attenuated

44
Q

What type of vaccine is the vaccine for Yellow fever?

A

Live attenuated

45
Q

What type of vaccine is the vaccine for Rotavirus?

A

Live attenuated

46
Q

What type of vaccine is the vaccine for chickenpox (VZV)?

A

Live attenuated

47
Q

What type of vaccine is the vaccine for Sabin polio virus?

A

Live attenuated

48
Q

What type of vaccine is the vaccine for MMR?

A

Live attenuated

49
Q

What type of vaccine is the vaccine for Influenza (intranasal)?

A

Live attenuated

50
Q

What type of vaccine is the H. influenzae type B vaccine?

A

conjugated vaccines for encapsulated bacteria

51
Q

What type of vaccine is the Meningococcal vaccine?

A

conjugated vaccines for encapsulated bacteria

52
Q

What type of vaccine is the Prevner vaccine?

A

conjugated vaccines for encapsulated bacteria

Pneumococcal PCV

53
Q

Name two examples of subunit vaccines?

A

Subunit vaccines include Hepatitis B (HBsAg of HBV)

-and-

Human Papillomavirus (Gardasil covers HPV types 6, 11, 16, and 18).
c
54
Q

What type of vaccine is the Rabies vaccine?

A

Killed vaccines

55
Q

What type of vaccine is the Influenza vaccine?

A

Killed vaccines

56
Q

What type of vaccine is the Salk vaccine?

A

Killed vaccines

57
Q

What type of vaccine is the Hepatitis A (HAV) vaccine?

A

Killed vaccines

58
Q

_______________ syndrome is cuased by C. trachomatis. What is the triad of Sx that make up this syndrome?

A

Reactive Arthritis (Reiter’s Syndrome)

  • arthritis
  • urethritis
  • conjuctivitis
59
Q

Which Hepatitis B antigen is the best marker of viral activity?

A

HepB “e” antigen, which is produced during viral replication in the bloodstream. (Also indicates low transmissibility.)

Real-time PCR for HBV DNA can also be used to assess viral activity.

60
Q

Which serologic marker indicated immunity to future hepatitis B infections?

A

Anti-HBs

Anti-HBs is an antibody to HBsAg and indicated immunity and marker of cleared infection to HBV.

61
Q

The chancre from _______ infection is noted to having a painless, non-exudative, clean, hard base with indurated margins (“punched out base with rolled edges”).

The chancroid from what bug is PAINFUL?

A

T. pallidum

Hemophilus ducreyi infection, described as a deep, undermined, painful purulent ulcer with soft ragged edges.

62
Q

What is the CV manifestation of tertiary syphillis?

A

affects ascending thoracic aorta. –> Dilated Aorta and Aortic Valve Regurg.

63
Q

What is the morphology of Treponema pallidum and what disease does it cause?

A

microaerophilic spirochete –>

syphilis

64
Q

What does Anti-HBc indicate in serology?

A

Anti-HBc is antibody to HBcAg. IgG Anti-HBc indicates a prior exposure to the virus.

65
Q

What is the serology of a Pt. with an ACUTE infection of Hep B?

HbsAg ---> ?
anti-HBs ---> ?
anti-HBc IgM or IgG ??HBeAg ---> ? 
anti-HBe  ---> ?
HBV DNA  ---> ?
A

HbsAg+, anti-HBs-, anti-HBc IgM, HBeAg+, anti-HBe-, HBV DNA+ is a pattern seen in acute infection.

66
Q

Which bacterial exotoxins functions as proteases? (5)

A
  • C. botulinum toxin
  • C. tetanus toxin
  • B. anthracis LF toxin
  • Staph aureus exfoliatin
  • Strep pyogenes exotoxin B (SpeB)
67
Q

Which bacterial exotoxins increase cAMP? (6)

ADP-ribosylation –> activated G_s –> incrases cAMP –> watery diarrhea

A
  • Pertussis toxin
  • Edema EF (B. anthracis)
  • Cholera toxin
  • Heat Labile (LT) toxin of ETEC
  • B. Cereus enterotoxin
  • Campy jejuni enterotoxin
68
Q

What does superantigen work?```

A

Superantigens function by cross-linking the α chain of MHC-II on the antigen-presenting cell with the variable region of the β-chain (Vβ) of T cell receptors on CD4+ Th cells. This creates polyclonal T-cell activation, leading to increased IL-2 and IFN-γ. The resulting release activates macrophages and promotes the release of proinflammatory cytokines such as IL-1, IL-6, TNF-α.

69
Q

Which bacterial exotoxin increase cGMP? (thereby increase secretions)

A
  • ST (heat-stable toxin of ETEC)

- Enterotoxin of Yersinia enterocolitica

70
Q

What two bacterial exotoxins use ADP-ribosylation to inactive EF-2 –> inhibition of protein synthesis?

A
  • Diphtheria toxin and exotoxin A of Pseudomonas spp.
71
Q

What are the exotoxins which form pores in cell membranes? (4)

A
  • Clostridium perfringens enterotoxin
  • Bacillus anthracis protective antigen (PA) factor
  • Staphylococcus aureus alpha-toxin
  • Streptococcus pyogenes streptolysin O
72
Q

Pertussis toxin works by _____________ that inactivates Gi, increasing cAMP and secretions that lead to edema.

A

ADP-ribosylation

73
Q

Pertussis toxin works by ADP-ribosylation that results in what?

A

inactivates Gi, increasing cAMP and secretions that lead to edema.

74
Q

Exotoxins which inhibit protein synthesis include (4)

A
  • Diphtheria toxin
  • Exotoxin A of Pseudomonas spp.
  • Verotoxin (Shiga-like toxin) of EHEC
  • Shiga toxin of Shigella spp.
75
Q

Drug induced-hemolytic anemia is classically associated with what drugs? (Although can happen with any drugs)

A
  • PCNs
  • Cephalosporins
  • Quinidine
  • Levodopa/methyldopa.
76
Q

infects small intestine; flagellated, crescent-shaped protozoan organism has a characteristic “facelike” appearance.

==???

A

Giardia lamblia is the most prevalent protozoan infection in the human small intestine.

77
Q

intracellular protozoan, causes diarrhea, visuallized as red or pink stained oocystuding modififed acid-fast stain.

== ??

A

cryptosporidum parvum

78
Q

usually infects the large intestine and/or liver; produces inverted flask-shaped lesions in large intestine with extension to peritoneum and liver, lungs, brain, and heart.

A

Entamoeba histolytica

79
Q

what Amoebae causes PAM if the pt. is swimming in warm, freshwater lakes; and how does it enter the body?

A

Primary amebic meningoencephalitis: Naegleria fowleri.

Acquired from diving into warm, freshwater lakes;
Amoebae enter the brain through cribriform plate during forceful diving.

Treatment: amphotericin B (rarely successful)

80
Q

________ is a gram-positive, anaerobic rod that is associated with gangrene and a mild form of food poisoning via an enterotoxin.

A

C. perfringens

81
Q

_____________ is a gram-negative, lactose-negative rod associated with bloody diarrhea but not with gastric ulcers.

A

Shigella dysenteriae

82
Q

There is an important association between colon cancer and endocarditis due to _____________.

A

Streptococcus bovis

S. bovis is a group D Streptococcus whose cell wall has glycerol teichoic acid.

83
Q

The triad of arthritis, urethritis, and conjunctivitis == ???

A

Reiter syndrome (reactive arthritis):

~w. HLA-B27

84
Q

Previous infection wath what bugs can lead to Reiter syndrome (reactive arthritis)?

A
  • Shigella
  • Salmonella
  • Yersina
  • Campylobacter
  • Chlamydia
85
Q

Hematogenous spread of N. gonorrhoeae infection –> ???

A

Septic Arthritis

86
Q

Gram-Neg, oxidase-neg bacillus = ???

A

Klebsiella pneumoniae;

~w/ alcoholism, lobar consolidation, and “currant jelly” sputum.

87
Q

A gram-negative, oxidase-positive bacillus describes ???

A

Pseudomonas aeruginosa

88
Q

Gram-Positive, catalase-neg, coccus descirbes what genus?

A

Strepococcus

89
Q

What is the immunodiffusion test used to identify toxin-producing strains of Corynebacterium diphtheriae.

A

ELEK test

90
Q

What test would be used to identify Neisseria, Pseudomonas, and Vibrio and distinguish them from members of the family Enterobacteriaceae?

A

Oxidase test

91
Q

What virus is a member of the Hepevirus family and whose infection of pregos has a high mortality rate?

A

Hepatitis E virus belongs to the Hepevirus family, which has naked, single-stranded, positive-sense RNA.

92
Q

Which hepatitis virus is part of the Flaviviridae family

A

HepC

93
Q

What is the family to which hepatitis B virus belongs?

A

Hepadnaviridae

It is an enveloped double-stranded DNA virus that is sexually or parenterally transmitted.

94
Q

What is the family to which hepatitis A virus belongs?

A

Picornaviridae

naked capsid RNA viruses to which hepatitis A virus belongs

95
Q

Immunocuppressed pt. with fungal meningitis, think?

A

Crytococcus neofromans.

encapsulated yeast acquired from pigeon droppings and urease-positive.

96
Q

encapsulated yeast acquired from pigeon droppings and urease-positive.

dX via laxtex particle agglutination of CSF

A

Crytococcus neofromans.

97
Q

Intracellular yeast within Macrophages are the diagnostic form of _______________ , which, despite its name, is not an encapsulated yeast. It is primarily a pulmonary infection acquired by exposure to the droppings of birds or bats.

A

Histoplasma capsulatum

98
Q

what would be the yeast forms characteristic of Coccidioides immitis, which may be a cause of fungal meningitis in immunologically compromised individuals but is geographically restricted to the Sonoran desert zone of the United States (San Joaquin Valley fever).

A

Spherules

99
Q

what organism causes regional lymphadenopathy, +/- low-grade fever and headaches?

A

Bartonella henselae; “cat-scratch fever”

in the immunocompromised, can cause bacillary andiomatosis.

tx. with Azithromycin or doxycyline

100
Q

What is marked by mild nonspecific symptoms or pneumonia, and may progress to myocarditis or hepatitis?

A

Q fever!

Coxiella burnetii

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