export_cns bacteria ii Flashcards
Strep. agalactiae features
Gram-positive cocci in chains
Catalase negative
Beta-hemolytic
Serologically group B
Positive cAMP test
Resists bacitracin
GBS colonization
Lower GI and GU tract
Vaginal colonization may occur as well
Maternal intrapartum GBS colonization is a major risk factor
GBS virulence factors
Polysaccharide capsule
When does early-onset GBS occur?
First week of life
Symptoms of early-onset GBS disease
Bacteremia
Pneumonia
Meningitis
Survivors may suffer from permanent neurological sequelae
When does late-onset GBS occur?
1-3 weeks
Symptoms of late-onset GBS disease
Similar to early-onset
Survival rate is higher
Meningitis is more common
Neurological complications more common
Diagnose GBS infection
Recognize clinical signs
ID organism
Serology
GBS treatment
Penicillin
Prevention of GBS disease
Universal screening of women between 35-36 week’s gestation
Penicillin given about 4 hours prior to delivery
Hemophilus influenzae type B features
Gram-negative rod
Fastidious (requires hemin and NAD)
Chocolate agar
6 serotypes (a through f)
Which hemophilus influenzae produces meningitis most commonly?
Type b, PRP capsule
Hib meningitis symptoms
Fever, stiff neck, headache
~25% of survivors experience neurological sequelae
Hib diagnosis
Gram-stain
Latex agglutination test
Hib meningitis treatment
Penicillin
Hib meningitis prevention
Conjugated vaccine
Anti-PRP Abs
Begin at 2 months of age
Clostridium tetani features
Gram-positive rod
Anaerobic
Spore forming
Produce neurotoxin (tetanospasmin)
C. tetani transmission
Spores enter via wound contamination or traumatic inoculation
Umbilical stump can be contaminated, resulting in neonatal tetanus
C. tetani lifecycle
Spores germinate in anaerobic conditions
Tetanoplasmin produced by vegetative cells
Toxin enters the blood stream, then the nervous system
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
C. tetani treatment
Administer Ig (passive) Vaccinate with tetanus toxoid (active)
Binding is irreversible; symptoms resolve as new axonal termini are generated
C. tetani prevention
Vaccine - DTaP
Begin at 2 months, boosters every 10 years
Clostridium botulinum features
Gram-positive rod
Anaerobic
Spore formation
Produce neurotoxin - botulinum toxin
C. botulinum intoxication
Ingestion of preformed toxin
Absorbed from gut into blood stream
C. botulinum toxin features
AB toxins
Binds to and enters motor neurons
Blocks the release of Ach
Results in flaccid paralysis
Listeria monocytogenes features
Gram-positive rod
Motile
L. monocytogenes CNS disease
Can cause meningitis
Pregnant women can be infected, resulting in stillbirth, premature delivery, etc.
Mycobacterium tuberculosis CNS disease
Can cause meningitis, brain abscess
Disease develops slowly
S. aureus CNS infection
Meningitis (following bacteremia)
Brain abscesses - trauma/surgery
