Lect 16 Flashcards
1
Q
define meningitis
A
inflammation resulting from an infection within the subarachnoid space (houses CSF)
2
Q
define encephalitis
A
inflammation in the parenchyma
3
Q
define chronic meningitis
A
symptom progressive or persistence > or = 4 weeks
4
Q
what major pathogen that causes meningitis has a vaccine
A
Haemophilus influenzae
5
Q
what are the pathogens most responsible for community acquired meningitis
A
- s. pneumoniae: most common cause of bacterial meningitis
- H. influenza
- N. menigitidis
- *usually caused by organisms able to colonize the respiratory tract
6
Q
list pathogenesis steps of bacterial meningitis
A
- 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
7
Q
What is the most common pathway for gaining access to the CNS
A
- invasion of the bloodstream and seeding of the CNS
8
Q
what is the classic triad of meningitis
A
- fever
- headache
- neck stiffness
9
Q
what are some additional signs and symptoms of NEONATAL bacterial meningitis
A
- bulging fontanelle
- high pitched cry
- hypotonia
- paradoxic irritability
- quiet when stationary, crying when held
10
Q
treatment of meningitis
A
- prompt initiation of empiric therapy
- steroids (usually dexamethasone)
- intrathecal antibiotics for hospital acquired infections
- injection into the spinal canal
11
Q
what is purulent meningitis
A
intense acute congestion of meningeal blood vessels and purulent exudate
12
Q
what are neonatal risk factors for meningitis
A
- immaturity of host defense mechanism
- low birth weight
13
Q
what are maternal risk factors for neonatal meningitis
A
- premature rupture of membranes
- urogenital infection during late term
- intrauterine infections during early term
- invasion of the uterine space
14
Q
neonatal meningits is characterized by what unique sign
A
Hyperthermia
15
Q
what are the predominant agents of neonatal meningitis
A
- streptococcus agalactiae: also known as group B streptococcus
- E-coli
- Listeria monocytogenes
16
Q
CDC recommendations for prevention of neonatal meningitis
A
- 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
17
Q
where are streptococcus agalactiae normally found
A
- colonizes vagina, GI tract and upper respiratory tract of healthy individuals
18
Q
streptococcus agalactiae
- gram status
- presentation on blood agar
A
- gram positive coccus
- gray white colonies with B hemolysis
19
Q
virulence factors of streptococcus agalactiae
A
- capsular polysaccharid
- hyaluronidase
- collagenase
- hemolysin
20
Q
early onset neonatal group B streptococcal infection
- maternal complications?
- when do symptoms develop?
A
- maternal obstetric complications are common
- symptoms develop during first 5 days of life
21
Q
early onset neonatal group B streptococcal infection has what major clinical manifestations?
A
- bacteremia
- pneumonia
- meningitis
22
Q
late onset neonatal group B streptococcal infection has what major clinical manifestations?
A
- bone/joint infections
- bacteremia
- concomitant/fulminant meningitis
23
Q
late onset neonatal group B streptococcal infection
- maternal complications?
- when do symptoms develop
A
- maternal obstetric complications are uncommon
- symptoms develop from 7 days to 3 months of age
24
Q
How is S. agalactiae diagnosed?
A
- definitive diagnosis requires isolation from blood, CSF
- detection of CAMP factor
- accentuation of hemolysis due to interaction with staph B-lysin
25
E-coli
* gram status
* shape
gram negative enteric bacillus
26
which strains of E-coli are associated with meningitis
encapsulated (K1) strains
27
how do neonates get neonatal meningitis from E-coli
* source is rectal colonization of mother's vagina
* \*\*not an endogenous infection
28
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
29
what is the epidemiology of pneumococcal meningitis
* acute purulent meningitis may follow pneumococcal PNA, infection at another site, or appear with no antecedent infection
30
what are predisposing conditions for pneumococcal meningitis
* multiple myeloma
* sickle cell disease
* cardiorespiratory disease
* congenital defects
31
Haemophilus influenzae
* gram status
* motile?
* shape?
* gram negative
* non-motile
* coccobacillus
32
virulence factor of Haemophilus influenzae
contains LOS: lipooligosaccharide
33
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
34
which causative agents of meningitis are more common in winter
* N. meningitidis
* S. pneumoniae
* S. agalactiae
* H. influenzae type B: late winter-early spring
35
which causative agent of meningitis is most common in summer
L. monocytogenes
36
meningitis caused by H. influenzae normally affected what patient population
infants (7-18 months)
37
meningitis caused by N. meningitidis normally affected what patient population
* 1 month old - 19 y.o
38
meningitis caused by strep pneumoniae normally affects what patient population
* 1 m.o - 4 y.o.
* adults (especially elderly)
39
meningitis caused by s. agalactiae normally affects what patient population
* neonates \< 1 m.o
* adults
40
meningitis caused by L. monocytogenes normally affects what patient population
* newborns
* predisposed adults
41
L. monocytogenes
* gram status
* shape
* motile
* oxygen?
* gram positive
* motile
* coccobacillus
* non-fastidious and grows at temp 0-50 C
42
how does Listeria monocytogenes exist in body
* Facultative intracellular pathogen
* in epithelial cells
* in macrophages and monocytes
43
where is Listeria monocytogenes found in environment
* animal and human carriers
* found in living and nonliving matter
* vegetables
* plants
* soil
* feces
44
virulence factors of Listeria monocytogenes
* **lipopolysaccharide-like surface component**
* **listeriolysin O**
* disrupts phagolysosome membrane
* induces apoptosis
45
how is Listeria monocytogenes infection gotten
ingestion of raw, contaminated food
46
what are the two main manifestations of Listeria monocytogenes
* sepsis
* meningitis
47
how do neonates get Listeria monocytogenes
* acquired from mom's genital tract -\> results in meningitis
48
what is the leading cause of meningitis in CA and renal transplant patients
Listeria monocytogenes
49
how is Listeria monocytogenes diagnosed
* culture
* homogenization is required for tissues
* "tumbling" motility in hanging drop preparation
50
treatment of Listeria monocytogenes
DOC: IV ampicillin
51
what is the causative agent of meningococcal meningitis
Neisseria meningitidis
52
Neisseria meningitidis
* gram status
* capsule
* most important serogroups
* gram negative
* encapsulated
* A, **B**, C, Y, W135
53
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)**
54
reservoir for meningococcal meningitis
* humans
* nasopharynx is colonized
55
Clinical presentation
* skin rash
* petechiae and pink macules
* DIC and gram negative shock can occur
meningococcal meningitis
56
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_
57
how is meningococcal meningitis treated
DOC: penicillin G
