Bacterial Meningitis Flashcards
What is the most common causitive agent of bacterial meningitis? What is the most common cause of neonatal meningitis?
strep pneumo; strep agalactiae
What are the most common causes of community acquired meningitis?
s. pneumo, h. flu, n. meningitidis
What are the most common causes of hospital acquired meningitis?
gram negative rods, s. aureus, other strep or staph
What causes a sudden neck or head pain in meningitis? What is it followed by?
Huge release of inflammatory cytokines, followed by WBC diapedesis into the CSF
What are the three pathways for gaining access to the CNS for meningitis?
Invasion of blood stream and seeding of the CNS (most common), retrograde neuronal pathway (Naegleria), direct contiguous spread (infections, congenital malformations, etc)
What does WBC diapedesis into the brain lead to?
Increased permeability of BBB, increased ICP and edema, eventual decrease in BF to the brain
What is the classic triad of meningitis sx?
Fever, headache, neck stiffness! Also sleepiness, confusion, delirium
What will you find in a hx of meningitis pt?
Exposure to patients with similar illness!!!!! (onset, setting)
A 4 month old infant presents with a bulging fontanelle, a high pitched cry that disappates when he is left alone (paradoxic irritability), and hypotonia. What is at the top of your differential?
Bacterial meningitis!!!
What are some generalized tests to be used to diagnose meningitis?
CBC, serum electrolytes, SERUM GLUCOSE COMPARED WITH CSF GLUCOSE, liver profile
What additional tests can you order to check for meningitis?
Lumbar puncture, cultures, neuroimaging
What is the treatment for meningitis (general)?
empiric abx therapy, steroid (dexamethasone) for swelling, intrathecal abx for hospital acquired
What would you call an intense acute congestion of meningeal blood vessels and purulent exudate?
Purulent meningitis
What are maternal predisposing factors for neonatal meningitis?
premature rupture of membranes, urogenital infection during LATE term, intrauterine infection during EARLY term
What are neonatal predisposing factors for neonatal meningitis?
Immaturity of host defense and immaturity of organ systems (low birth weight)
What are signs and symptoms of neonatal meningitis?
Hyperthermia (usual) or hypothermia (dysregulation in general)
CNS manifestations (lethargy, irritability, seizures)
GI disturbance
Respiratory abnormalities
What are the predominant agents of neonatal meningitis?
Streptococcus agalactiae (group B strep)
E. Coli
Listeria monocytogenes
What are the CDC recommendations to prevent neonatal meningitis?
Universal prenatal screening for vaginal or rectal group B strep for all PGN women 35-37 weeks
What is the exception to routine antibiotic prophylaxis for group B strep positive women at the end of term?
undergoing planned C-section AND who have not begun labor or had rupture of membranes
What is the prognosis for neonatal meningitis?
Generally poor, survivors have permanent defects
You are looking at a gram positive coccus with a gray-white colony and a narrow zone of B-hemolysis. What is it?
Strep Agalactiae
What are the four virulence factors found in strep agalactiae?
capsular polysaccharide
hyaluronidase
collagenase
hemolysin
A 15-day old neonate presents with GBS. What are some clinical manifestations and what is his prognosis?
bone/joint infections, bacteremia (left shift), and meningitis
Where should you obtain a culture for GBS from?
A normally sterile site (blood, CSF, areas with mixed flora)
What is one presumptive lab test for GBS? What does it look for?
CAMP factor; accentuation of hemolysis due to interaction with staph B-lysin
You have a gram negative enteric bacillus. What is it and is it considered an endogenous neonatal meningitis infection?
E. Coli, and no, not considered endogenous
Almost all meningitis caused by s. pneumo follows what type of infection?
Pneumonia!
Gram positive, alpha hemolytic, lancet shaped diplococci
strep pneumo
Why are the elderly the most commonly affected population of strep pneumo infection?
because youth can get the vaccine
Non-motile, G- coccobacillus with LOS
H. Flu
What is the usual pattern of meningitis caused by H. flu?
Several days of mild antecedent infection followed by a deterioration and signs and symptoms of meningitis
What bacterium is the exception to community-acquired meningitis outbreaks?
Listeria is usually in the summer and in newborns
What are the oxygen requirements of listeria in vitro? What about temperatures?
reduced O2 tension; non-fastidious so it grows and temps from 0-50* (grows well in the fridge!)
Gram positive, motile coccobacillus that is a facultative intracellular pathogen with a worldwide distrubution
Listeria monocytogenes
You just get back from a BBQ with coleslaw, raw hot dogs, undercooked chicken, what agent are you concerned about that has the ability to infect living and nonliving matter?
Listeria monocytogenes
Which VF of listeria leads to its antiphagocytic ability?
LPS-like surface component
What is the VF of listeria that disrupts the phagolysosome membrane? What else does it do?
Listeriolysin O; inhibits antigen processing and induces apoptosis
What are the two main manifestations of listeriosis? What happens if it is acquired in utero?
sepsis and meningitis; stillbirth, abortion, etc.
What is the leading cause of meningits in cancer and renal transplant patients? What is its classic feature?
Listeriosis; brain stem encephalitis
What is the typical way of diagnosing listeriosis?
“tumbling” motility in hanging drop preparation
AccuProbe (DNA probe technology)
Meningococcal meningitis is caused by which organism?
Neisseria meningitidis
fastidious, gram negative, kidney bean shaped diplococcus
Neisseria meningitidis
Which serotypes of neisseria meningitidis have conjugate and non-conjugate vaccines given to adolescents (age 11)?
A, C, Y, W135 (all except B)
What is the reservoir for neisseria meningitidis?
HUMANS ARE THE ONLY RESERVOIR (nasopharynx)
You live in a college dorm and your brother is in the military and lives in the barracks. What infection are you both at risk for?
Meningococcal meningitis (n. meningitidis)
What is the hallmark clinical sign of meningococcemia?
characteristic petechial rash
What agar is used for cultivation of Neisseria Meningitidis?
Thayer-Martin agar (3 abx plus nystatin)
What is the DOC for Neisseria meningitidis? What are the alternatives?
PCN G; chloramphenicol or 3rd gen ceph
