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CMBM E3 CB > Gram Negative Bacteria > Flashcards

Gram Negative Bacteria Flashcards

1
Q

N. meningitidis reservoir

A
  1. Nasopharynx of humans
  2. Spread by respiratory transmission

*strict human parasite

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2
Q

N. meningitidis virulence factors

A
  1. Capsule: anti-phagocytotic
  2. IgA protease
  3. Unique proteins that can extract iron from transferrin, lactoferrin, and hemoglobin
  4. Pili: for adherence
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3
Q

N. meningitidis toxins

A
  1. LPS endotoxin
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4
Q

N. meningitidis clinical presentation

A
  1. Asymtomatic carriage in the nasopharynx
  2. Meningitis:
    Fever
    Nuchal rigidity
    *Vomiting
    Petechial rash
  3. Septicemia
    Fever
    Petechial rash
    Hypotension
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5
Q

N. meningitidis treatment

A

Penicillin G
Ceftriaxone
Rifampin and cipro for prophylaxis of close contacts of infected persons

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6
Q

Which demographic is most susceptible to N. meningitidis?

A
  1. Neonates–very susceptible from 6 to 24 months, when protective antimeningococcal IgG is low
  2. Army recruits
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7
Q

N. gonorrhoeae clinical presentation

A
  1. Men: urethritis
  2. Women: cervical gonorrhea—->PID
  3. Both: septic arthritis
  4. Neonates: Conjunctivitis
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8
Q

N. gonorrhoeae treatment

A
  1. Ceftriaxone ( + doxycycline for probable concurrent Chlamydia infection)
    * penicillin resistant
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9
Q 
Chocolate agar
Gram-negative diplococci in cerebrospinal fluid
Lipooligosaccharide
Petechiae
Septic shock
Thayer Martin agar
Waterhouse-Friderichsen syndrome
A

N. meningitidis

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10
Q 
Chocolate agar
Gram-negative diplococci
Oxidase positive
STD
Thayer-Martin agar
Urethritis
A

N. gonorrhoeae

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11
Q

Produces fluroscein –> fruity, grape-like smell

A

Pseudomonas aeruginosa

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12
Q

Pseudomonas aeruginosa virulence factors

A

Exotoxin A –> paralyzes host cell protein machinery (similar to diphtheria toxin)
Phospholipase C –> damages host cell membrane
Elastase –> allows microorganism to disseminate to better nutrient sources
Endotoxin –> shock

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13
Q

Pseudomonas aeruginosa clinical presentation

A 
UTIs (hospital patients; 3rd most common cause in all people)
Pneumonia (CF patients)
Burn wound infection
Hot tub infections
Endocarditis (IV drug users)
Swimmer's ear
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14
Q

Pseudomonas aeruginosa treatment

A

HIGHLY RESISTANT

Aminoglycosides
Ceftazidime

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15
Q

Bordetella pertussis reservoir

A

Humans are the only natural carriers

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16
Q

Bordetella pertusis mode of transmission

A
  1. Airborne transmission
  2. Adheres to cilia of respiratory epithelium via filamentous hemagglutinin (FHA)
  3. Releases exotoxins to generate disease
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17
Q

Bordetella pertussis virulence factors

A
  1. Polysaccharide capsule
  2. Outer membrane protein (adhesion)
  3. Pertussis toxin –> AB toxin –> uninhibited adenylate cyclase (taken up by phagocytes; inhibits bactericidal activity)
  4. Tracheal cytotoxin –> destroys ciliated epithelial cells –> impairs mucuous clearance –> violent whooping cough –> promotes spread of bacteria
  5. FHA
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18
Q

Pertussis exotoxin mechanism

A

increases cAMP

  1. ADP-ribosylates and inactivates G proteins –> uninhibited adenylate cyclase –> cAMP increase
  2. Increased cAMP –> negative feedback inhibition –> increased cAMP
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19
Q

Pertussis toxin causes an increase in which hormone?

A

Insulin

Pertussis patients may also show signs of hypoglycemia

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20
Q

Pertussis treatment

A

Erythromycin

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21
Q

What percentage of pertussis patients will go on to develop pneumonia?

A

5%

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22
Q

Brucella reservoir

A

Zoonosis

Commonly infects cattle ranchers, slaughter house workers, vets

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23
Q

What agar does Brucella grow on?

A

Potator + eryhtritol (“Brusella agar”)

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24
Q

Brucella clinical presentation

A

Undulating fever (rises and falls)

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25
Q

Brucella treatment

A

Tetracycline

Rifampin

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26
Q

Most common complication of Brucella infection

A

Osteomyelitis

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27
Q

Francisella tularensis clinical presentation

A

Tularemias (site-specific infection + lymphadenopathy)

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28
Q

Pasturella multocida clinical presentation

A

Cellulitis, osteomyelitis following cat/dog bite

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29
Q

Two types of Haemophilus influenzae and their clinical presentations

A
  1. Typable (Hib): infantile meningitis, epiglotittis

2. Non-typable: otitis media, sinusitis, bronchitis, conjunctivitis

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30
Q

H. influenzae agar

A

Chocolate agar; requires hemin (X factor) and NAD (V factor)

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31
Q

Bacteroides fragilis reservoir

A

Normal human flora

Most abundant organism in colon

32
Q

Bacteroides fragilis clinical presentation

A

Most common cause of intra-abdominal infections
Peritonitis
Diverticulitis
Post-op abdominal abscesses

33
Q

B. fragilis agar

A

Bile esculin agar

34
Q

What is the most common cause of infectious diarrhea?

A

Campylobacter jejuni ( > Shigella & Salmonella combined)

35
Q

C. jejuni reservoir

A

Carried by poultry, cattle, dogs, and other domestic animals

Transmitted by fecal-oral route, ingestion of undercooked poultry or unpasteurized milk

36
Q

What grows on CAMPY agar?

37
Q

Which bacteria is associated with Guillain Barre syndrome?

A

C. jejuni

syndrome is an example of molecular mimicry

38
Q

C. jejuni treatment

A

Supportive (no abx)

39
Q

H. pylori clinical presentation

A

Acute:
gastritis

Chronic:
antral gastritis
peptic ulcers

40
Q

H. pylori treatment

A

Triple Chemotherapy:

  1. Proton pump inhibitor (e.g. omeprazole)
  2. Antibiotic (carithromycin, amoxicillin, or metronidazole)
  3. Bismuth compound
41
Q

How do you diagnose H. pylori infection?

A

Urease breath test

42
Q

Vibrio cholerae agar

A

Flat yellow colonies on TCBS agar

43
Q

Vibrio cholerae clinical presentation

A

Rice-water diarrhea

Dehydration

44
Q

What is the structure and mechanism of the cholera toxin?

A

Structure: Heat labile enterotoxin. A subunit plus 5 subunits encoded by separate genes in the CTX phage genome

Mechanism: B subunit binds to GM1 ganglioside receptor on host cell. A subunits are endocytosed and cause ADP ribosylation of G proteins –> adenylate cyclase –> cAMP increase –> loss of water, electrolytes

45
Q

V. cholerae treatment

A
  1. Fluid replacement

2. Tetracycline

46
Q

All enterobacteriaceae are ______ ______ and _____ _____.

A

Oxidase negative / facultative anaerobes

47
Q

Enterobacteriaceae are facultative anaerobes, which means they….

A

Ferment glucose and reduce nitrate

48
Q

What is the difference between the pertussis toxin and the cholera toxin?

A

Pertussis toxin “turns off” Gi (off) protein in respiratory epithelium.
Cholera toxin “turns on” G3 (on) protein in intestinal epithelium.

Both act by the same mechanism and both increase adenylate cyclase.

49
Q

Only gram-____ organisms grow on MacConkey agar.

50
Q

Salmonella agar

A

Black colonies on XLD agar

51
Q 
Diarrhea
Gram-negative rod
Lactose positive
Neonatal meningitis
Oxidase negative
UTI
52
Q

Aspiration
Capsule
Currant jelly sputum
Pneumonia

A

Klebsiella pneumoniae

Lung infection most common in alcoholic patients and those with poor pulmonary function

53
Q 
Dairy foods
Motile
Nonbloody diarrhea
Nonlactose fermenter
Raw eggs
Chicken
A

Salmonella

54
Q

Gram-negative bacillus
Lactose negative
No hydrogen sulfide
Watery, bloody diarrhea

55
Q

Plague
Rodent and animal host
Fleas
Buboes (inflamed swollen lymph nodes)

A

Yersinia pestis

56
Q

Elevated urine pH
Swarming growth on agar
Urease
UTI

A

Proteus mirabilis

57
Q 
Chocolate agar
Endotoxin
Gram-negative diplococci in CSF
Lipooligosaccharide
Meningitis
Oxidase positive
Petechiae
Thayer-Martin agar
Waterhouse-Friderichsen syndrome
A

Neisseria meningitidis

58
Q

Chocolate agar
Gram-negative diplococci
Oxidase positive
Urethritis

A

Neisseria gonorrhoeae

59
Q

Bordet-Gengou agar
DPT vaccine
Whooping cough

A

Bordatella pertussis

60
Q 
Capsule
Epiglottitis
Hib
Meningitis
Otitis
X and V factors
A

Haemophilus influenzae

61
Q

Air conditioning
Atypical pneumonia
Charcoal yeast agar
Warm mist/shower/lukewarm water

A

Legionella pneumophila

62
Q 
Burn patient
Cystic fibrosis
Fruity smell
Hot tub folliculitis
Opportunistic
A

Pseudomonas aeruginosa

63
Q

Chronic granulomatous disease
Cystic fibrosis
Pseudomonas-like

A

Burkholderia

64
Q

A-B toxin
Comma (S) shaped
Rice water diarrhea
Shellfish

A

Vibrio cholerae

65
Q

Bloody diarrhea
Thin, curved gram-negative
Undercooked poultry

A

Campylobacter jejuni

66
Q

Bacteria causing bloody diarrhea

A

C. jejuni
Shigella
Yersinia enterocolitica
E. coli

*except in young children, C. jejuni is the primary cause of bloody diarrhea in the U.S.

67
Q

Gastric or duodenal ulcer
Urease
Urease breath test

A

Helicobacter pylori

68
Q

Shigella toxin mechanism

A

Blocks protein synthesis causing intestinal cell death

69
Q

What is a significant virulence factor of uropathogenic E. coli?

70
Q

What is a common complication of Proteus-related UTIs?

A

Kidney stone formation. Proteus is urease positive, therefore it breaks down urea into ammonia. This leads to alkaline pH and stone formation.

71
Q

What is the main virulence factor of Klebsiella?

A

Antiphagocytotic capsule / K antigen

72
Q

Which virulence factor of H. pylori is linked with gastric adenocarcinoma?

73
Q

What is the main virulence factor in Neisseria species?

A

LOS endotoxin

74
Q

What is the main virulence factor of Pseudomonas aeruginosa?

A

Exotoxin A (ADP ribosylation of EF2 –> INHIBITS protein synthesis –> tissue damage)

75
Q

Non-spore forming INTRACELLULAR pathogen

76
Q

What is the mechanism of the Shiga toxin?

A

AB toxin: B5 binds specific glycosides on cell surface
A subunit causes irreversible inactivation of the 60S ribosomal subunit
This causes inhibition of protein synthesis, cell death, and hemorrhage

CMBM E3 CB (12 decks)

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