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Flashcards in export_cns bacteria ii Deck (29):
1

Strep. agalactiae features

Gram-positive cocci in chains
Catalase negative

Beta-hemolytic

Serologically group B

Positive cAMP test

Resists bacitracin

2

GBS colonization

Lower GI and GU tract
Vaginal colonization may occur as well

Maternal intrapartum GBS colonization is a major risk factor

3

GBS virulence factors

Polysaccharide capsule

4

When does early-onset GBS occur?

First week of life

5

Symptoms of early-onset GBS disease

Bacteremia
Pneumonia

Meningitis

Survivors may suffer from permanent neurological sequelae

6

When does late-onset GBS occur?

1-3 weeks

7

Symptoms of late-onset GBS disease

Similar to early-onset
Survival rate is higher

Meningitis is more common

Neurological complications more common

8

Diagnose GBS infection

Recognize clinical signs
ID organism

Serology

9

GBS treatment

Penicillin

10

Prevention of GBS disease

Universal screening of women between 35-36 week's gestation
Penicillin given about 4 hours prior to delivery

11

Hemophilus influenzae type B features

Gram-negative rod
Fastidious (requires hemin and NAD)

Chocolate agar

6 serotypes (a through f)

12

Which hemophilus influenzae produces meningitis most commonly?

Type b, PRP capsule

13

Hib meningitis symptoms

Fever, stiff neck, headache
~25% of survivors experience neurological sequelae

14

Hib diagnosis

Gram-stain
Latex agglutination test

15

Hib meningitis treatment

Penicillin

16

Hib meningitis prevention

Conjugated vaccine
Anti-PRP Abs

Begin at 2 months of age

17

Clostridium tetani features

Gram-positive rod
Anaerobic

Spore forming

Produce neurotoxin (tetanospasmin)

18

C. tetani transmission

Spores enter via wound contamination or traumatic inoculation
Umbilical stump can be contaminated, resulting in neonatal tetanus

19

C. tetani lifecycle

Spores germinate in anaerobic conditions
Tetanoplasmin produced by vegetative cells

Toxin enters the blood stream, then the nervous system

20

Tetanoplasmin features and toxicity

AB toxin
Binds to motor neurons

Internalized and transported to spinal cord

Inactivates the release of inhibitory neurotransmitters

Causes a spastic paralysis

21

C. tetani treatment

Administer Ig (passive)
Vaccinate with tetanus toxoid (active)

Binding is irreversible; symptoms resolve as new axonal termini are generated

22

C. tetani prevention

Vaccine - DTaP
Begin at 2 months, boosters every 10 years

23

Clostridium botulinum features

Gram-positive rod
Anaerobic

Spore formation

Produce neurotoxin - botulinum toxin

24

C. botulinum intoxication

Ingestion of preformed toxin
Absorbed from gut into blood stream

25

C. botulinum toxin features

AB toxins
Binds to and enters motor neurons

Blocks the release of Ach

Results in flaccid paralysis

26

Listeria monocytogenes features

Gram-positive rod
Motile

27

L. monocytogenes CNS disease

Can cause meningitis
Pregnant women can be infected, resulting in stillbirth, premature delivery, etc.

28

Mycobacterium tuberculosis CNS disease

Can cause meningitis, brain abscess
Disease develops slowly

29

S. aureus CNS infection

Meningitis (following bacteremia)
Brain abscesses - trauma/surgery