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Flashcards in Gram Negative Bacteria Deck (76)
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1

N. meningitidis reservoir

1. Nasopharynx of humans
2. Spread by respiratory transmission

*strict human parasite

2

N. meningitidis virulence factors

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

3

N. meningitidis toxins

1. LPS endotoxin

4

N. meningitidis clinical presentation

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

5

N. meningitidis treatment

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

6

Which demographic is most susceptible to N. meningitidis?

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

7

N. gonorrhoeae clinical presentation

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

8

N. gonorrhoeae treatment

1. Ceftriaxone ( + doxycycline for probable concurrent Chlamydia infection)

*penicillin resistant

9

Chocolate agar
Gram-negative diplococci in cerebrospinal fluid
Lipooligosaccharide
Petechiae
Septic shock
Thayer Martin agar
Waterhouse-Friderichsen syndrome

N. meningitidis

10

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

N. gonorrhoeae

11

Produces fluroscein --> fruity, grape-like smell

Pseudomonas aeruginosa

12

Pseudomonas aeruginosa virulence factors

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

13

Pseudomonas aeruginosa clinical presentation

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

14

Pseudomonas aeruginosa treatment

HIGHLY RESISTANT

Aminoglycosides
Ceftazidime

15

Bordetella pertussis reservoir

Humans are the only natural carriers

16

Bordetella pertusis mode of transmission

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

17

Bordetella pertussis virulence factors

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

18

Pertussis exotoxin mechanism

*increases cAMP*

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

19

Pertussis toxin causes an increase in which hormone?

Insulin
Pertussis patients may also show signs of hypoglycemia

20

Pertussis treatment

Erythromycin

21

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

5%

22

Brucella reservoir

Zoonosis
Commonly infects cattle ranchers, slaughter house workers, vets

23

What agar does Brucella grow on?

Potator + eryhtritol ("Brusella agar")

24

Brucella clinical presentation

Undulating fever (rises and falls)

25

Brucella treatment

Tetracycline
Rifampin

26

Most common complication of Brucella infection

Osteomyelitis

27

Francisella tularensis clinical presentation

Tularemias (site-specific infection + lymphadenopathy)

28

Pasturella multocida clinical presentation

Cellulitis, osteomyelitis following cat/dog bite

29

Two types of Haemophilus influenzae and their clinical presentations

1. Typable (Hib): infantile meningitis, epiglotittis
2. Non-typable: otitis media, sinusitis, bronchitis, conjunctivitis

30

H. influenzae agar

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