Bacterial Infections of the CNS II (meningitis and encephalitis) Flashcards
gram + cocci, grow in long chains, catalase negative, beta-hemolytic, group B,
Streptococcus agalactiae (GBS)
positive CAMP test
GBS (streptococcus agalactiae)
resistant to bacitracin
streptococcus agalactiae
common cause of sepsis and meningitis in newborns
GBS
more common in newborns and blacks
GBS meningitis
carriers have colonization of the lower GI tract and genitourinary tract, and some may have vaginal colonization leading to the development of early onset disease in infants
GBS maternal colonization
percentage of infants born of colonized mothers become colonized with the identical strain of GBS
50-60%
antibody mediated opsonization appears to be protective-in the absence of maternal antibodies the neonate is at risk
GBS meningitis
Amongst colonized newborns only 2% are symptomatic with early-onset sepsis, pneumonia, meningitis
GBS mother to infant transmission
bacteremia, pneumonia, meningitis-respiratory distress, labored breathing, fever, lethargy, and irritability
early-onset GBS infection
GBS surviving neonates may experience
permanent neurological sequela- blindness, deafness, and mental retardation
meningitis is more common (also neurological complications) and survival rate is higher
late-onset GBS infection
GBS infection dx:
clinical signs and identify the organisms
GBS Tx:
penicillin
leading infectious cause of neonatal morbidity and mortality
GBS early-onset disease
prevention of perinatal GBS disease
universal screening of all pregnant women at 35-36 weeks gestation, intrapartum antibiotics (penicillin) more than 4 hours before delivery
gram-negative rod, requires hemin (x) and NAD (V) for growth on chocolate agar, polysaccharide capsule (6 types) type B has poly-ribitol phosphat capsule (PRP)
Haemophilus influenzae type B
prior to vaccination was responsible for 95% of all invasive disease (Haemophilus influenzae) was due to
type B
encapsulated strains of Haemophilus influenzae cause
meningitis and epiglottitis
non-encapsulated strains of Haemophilus influenzae cause
pinkeye, otitis media, sinusitis
leading cause of pediatric meningitis
Haemophilus influenzae type B
Haemophilus influenzae type B tx/dx
same as other bacterial meningitis agents
Prevention of Haemophilus influenzae type B meningitis
non-conjugated vaccine (poorly immunogenic in kids and no booster response) conjugated (anti-PRP antibodies, highly immunogenic can vaccinate at 2 months)
gram-positive rod, anaerobic, spore forming (terminal drumstick), tetanospasmin toxin
Clostridium tetani
causes tetanus
Clostridium tetani
spores common in soil and in feces of domestic animals
clostridium tetani
How do Clostridium tetani infect humans?
spores enter the body through wound contamination or traumatic inoculation, also through the umbilical stump
What type of toxin is the tetanus toxin?
A-B toxin, B binds to motor neurons-internalized and transported to spinal cord
Clostridium tetani causes this type of paralysis
Spastic paralysis
inactivates the release of inhibitory neurotransmitters
tetanospasmin
early signs include “lock jaw” (trismus), neck stiffness, difficulty swallowing, abdominal muscle rigidity
Clostridium tetani-tetanus
symptoms of tetanus progress to
generalized muscle spasms including severe back spasms
death in tetanus usually occurs due to
respiratory failure
Why is tetanus difficult to detect
the toxin is bound to neurons and the organism is difficult to grow
Tx: tetanus
administer immunoglobulin, vaccinate with tetanus toxoid (REMOVE ANY UNBOUND TOXIN!)
Is the binding of the toxin reversible (tetanus)?
no it is irreversible-symptoms resolve as new axonal termini are generated
mortality rate of tetanus if untreated is roughly
15-60%
Prevention of Clostridium tetani-tetanus
vaccination with tetanus toxid (DTaP)
When should you begin vaccinating for tetanus?
at 2 months with booster every ten years
gram-positive rod, anaerobic, spore forming-terminal, botulinum toxin
Clostridium botulinum
Where are clostridium botulinum spores found?
soil, meat fish, veggies, improperly canned food
typically not an infection, but an intoxication (absorbed from gut into the blood stream
botulism
What kind of toxin is botulinum toxin?
A-B, B binds and A enters motor neuron, A blocks the release of acetylcholine, blocks stimulation of the muscle
Clostridium botulinum causes this type of paralysis
flaccid paralysis
Symptoms of Botulism (occur after 12 to 72 hrs post toxin ingestion)
nausea, dry mouth, blurred vision, involuntary eye movement, descending muscle paralysis
gram-positive rod (cocccobacillus), motile, found in water, soil, and the feces/GI tract of many animals
Listeria monocytogenes
infection usually a result of consumption of contaminated foods especially milk, soft cheese, poultry, and deli meats
Listeria monocytogenes
commonly causes meningitis in immunosuppressed individuals and pregnant women (5-10% of meningitis in older adults, 5-10% neonatal meningitis)
Listeria monocytogenes
infection in utero can result in stillbirth, premature delivery
Listeria monocytogenes
primarily a disease of the lung, but may infect the CNS-meningitis, brain abscess-chronic disease develops slowly!
Mycobacterium tuberculosis
most patients with meningitis caused by this agent have clinical historic evidence of pulmonary disease
Mycobacterium tuberculosis
Staph aureus can cause these CNS complications
meningitis following bacteremia, brain abscesses from traumatic inoculation or surgery
