Lect 16 Flashcards
define meningitis
inflammation resulting from an infection within the subarachnoid space (houses CSF)
define encephalitis
inflammation in the parenchyma
define chronic meningitis
symptom progressive or persistence > or = 4 weeks
what major pathogen that causes meningitis has a vaccine
Haemophilus influenzae
what are the pathogens most responsible for community acquired meningitis
- s. pneumoniae: most common cause of bacterial meningitis
- H. influenza
- N. menigitidis
- *usually caused by organisms able to colonize the respiratory tract
list pathogenesis steps of bacterial meningitis
- mucosal colonization
- entry into bloodstream
- penetration of BBB
- release of inflammatory cytokines
- WBC diapedesis into CSF -> increased permeability of BBB
- exudation of serum -> edema, inc intracranial pressure, altered blood flow
What is the most common pathway for gaining access to the CNS
- invasion of the bloodstream and seeding of the CNS
what is the classic triad of meningitis
- fever
- headache
- neck stiffness
what are some additional signs and symptoms of NEONATAL bacterial meningitis
- bulging fontanelle
- high pitched cry
- hypotonia
- paradoxic irritability
- quiet when stationary, crying when held
treatment of meningitis
- prompt initiation of empiric therapy
- steroids (usually dexamethasone)
- intrathecal antibiotics for hospital acquired infections
- injection into the spinal canal
what is purulent meningitis
intense acute congestion of meningeal blood vessels and purulent exudate
what are neonatal risk factors for meningitis
- immaturity of host defense mechanism
- low birth weight
what are maternal risk factors for neonatal meningitis
- premature rupture of membranes
- urogenital infection during late term
- intrauterine infections during early term
- invasion of the uterine space
neonatal meningits is characterized by what unique sign
Hyperthermia
what are the predominant agents of neonatal meningitis
- streptococcus agalactiae: also known as group B streptococcus
- E-coli
- Listeria monocytogenes
CDC recommendations for prevention of neonatal meningitis
- universal prenatal screening for vaginal or rectal colonization with group B strep for all pregnant woman at 35-37 weeks gestation
- routine abx prophylaxis for culture + women
where are streptococcus agalactiae normally found
- colonizes vagina, GI tract and upper respiratory tract of healthy individuals
streptococcus agalactiae
- gram status
- presentation on blood agar
- gram positive coccus
- gray white colonies with B hemolysis
virulence factors of streptococcus agalactiae
- capsular polysaccharid
- hyaluronidase
- collagenase
- hemolysin
early onset neonatal group B streptococcal infection
- maternal complications?
- when do symptoms develop?
- maternal obstetric complications are common
- symptoms develop during first 5 days of life
early onset neonatal group B streptococcal infection has what major clinical manifestations?
- bacteremia
- pneumonia
- meningitis
late onset neonatal group B streptococcal infection has what major clinical manifestations?
- bone/joint infections
- bacteremia
- concomitant/fulminant meningitis
late onset neonatal group B streptococcal infection
- maternal complications?
- when do symptoms develop
- maternal obstetric complications are uncommon
- symptoms develop from 7 days to 3 months of age
How is S. agalactiae diagnosed?
- definitive diagnosis requires isolation from blood, CSF
- detection of CAMP factor
- accentuation of hemolysis due to interaction with staph B-lysin
E-coli
- gram status
- shape
gram negative enteric bacillus
which strains of E-coli are associated with meningitis
encapsulated (K1) strains
how do neonates get neonatal meningitis from E-coli
- source is rectal colonization of mother’s vagina
- **not an endogenous infection
what is the most common cause of bacterial meningitis
S. pneumoniae
- all ages are affected,
- but it is the most common agent in the elderly
what is the epidemiology of pneumococcal meningitis
- acute purulent meningitis may follow pneumococcal PNA, infection at another site, or appear with no antecedent infection
what are predisposing conditions for pneumococcal meningitis
- multiple myeloma
- sickle cell disease
- cardiorespiratory disease
- congenital defects
Haemophilus influenzae
- gram status
- motile?
- shape?
- gram negative
- non-motile
- coccobacillus
virulence factor of Haemophilus influenzae
contains LOS: lipooligosaccharide
what is the usual clinical pattern of meningitis caused by Haemophilus influenzae
- prior URI and associated or preceding otitis media
- several days of mild antecedent infection
- followed by deterioration, signs and symptoms of meningitis
which causative agents of meningitis are more common in winter
- N. meningitidis
- S. pneumoniae
- S. agalactiae
- H. influenzae type B: late winter-early spring
which causative agent of meningitis is most common in summer
L. monocytogenes
meningitis caused by H. influenzae normally affected what patient population
infants (7-18 months)
meningitis caused by N. meningitidis normally affected what patient population
- 1 month old - 19 y.o
meningitis caused by strep pneumoniae normally affects what patient population
- 1 m.o - 4 y.o.
- adults (especially elderly)
meningitis caused by s. agalactiae normally affects what patient population
- neonates < 1 m.o
- adults
meningitis caused by L. monocytogenes normally affects what patient population
- newborns
- predisposed adults
L. monocytogenes
- gram status
- shape
- motile
- oxygen?
- gram positive
- motile
- coccobacillus
- non-fastidious and grows at temp 0-50 C
how does Listeria monocytogenes exist in body
- Facultative intracellular pathogen
- in epithelial cells
- in macrophages and monocytes
where is Listeria monocytogenes found in environment
- animal and human carriers
- found in living and nonliving matter
- vegetables
- plants
- soil
- feces
virulence factors of Listeria monocytogenes
- lipopolysaccharide-like surface component
-
listeriolysin O
- disrupts phagolysosome membrane
- induces apoptosis
how is Listeria monocytogenes infection gotten
ingestion of raw, contaminated food
what are the two main manifestations of Listeria monocytogenes
- sepsis
- meningitis
how do neonates get Listeria monocytogenes
- acquired from mom’s genital tract -> results in meningitis
what is the leading cause of meningitis in CA and renal transplant patients
Listeria monocytogenes
how is Listeria monocytogenes diagnosed
- culture
- homogenization is required for tissues
- “tumbling” motility in hanging drop preparation
treatment of Listeria monocytogenes
DOC: IV ampicillin
what is the causative agent of meningococcal meningitis
Neisseria meningitidis
Neisseria meningitidis
- gram status
- capsule
- most important serogroups
- gram negative
- encapsulated
- A, B, C, Y, W135
is there a vaccine for meningococcal meningitis
- (A, C, Y, W135) is used for children, adolescents and person at high risk
- new vaccine for serogroup B: Trumenba (pfizer)
reservoir for meningococcal meningitis
- humans
- nasopharynx is colonized
Clinical presentation
- skin rash
- petechiae and pink macules
- DIC and gram negative shock can occur
meningococcal meningitis
how is meningococcal meningitis diagnosed
- gram stain of CSF
- detection of capsular polysaccharide in CSF
- chocolate agar and thayer-martin agar
- supplemented with abx: vancomycin, colistin, bactrim
how is meningococcal meningitis treated
DOC: penicillin G
