Flashcards in Bacterial infx CNS Deck (72):
What are the two categories of CNS infections?
1. Those involving the meninges (meningitis)
2. Those which are confined to the brain (encephalitis)
What is the blood-brain barrier? What are the three functions it provides?
1 Separates blood and CSF
2. Provides physical isolation for the CNS
3. Protects the CNS, but not the PNS
What must microbes be able to do to cause CNS infections?
Disrupt the BBB
What is the BBB made of?
Tight junctions between endothelial cells and the cerebral microvasculature, cpithelial cells of the chorid plexus, and arachoind cells
What two features of the epithelial cells that comprise the BBB make them a good barrier?
1. Tight junctions
2. Little pinocytosis/channels
How do CNS infections usually start? (3)
1. Bacteremia or spread from a site adjacent/contiguous with the CNS
2. Direct inoculation (rare)
3. Neuronal spread
What are the three categories of meningitis? What are the usual causes of each?
1. Acute pyogenic (bacterial)
2. Aseptic (viral)
3. Chronic (any class)
Bacterial meningitis is more or less fatal than viral?
What are the predisposing factors to pneumococcal meningitis? (2)
Pneumonia and chronic OM
What are the predisposing factors to meningococcal meningitis? (2)
1. h/o recent URI (viral)
2. Complement deficiencies
Which type of meningitis occurs frequently in complement deficiencies?
Where/when are meningococcal outbreaks (specifically) common?
Schools and military barracks
What are the two common features of the bacteria that cause meningitis?
What is the function of the capsule of the meningitis-causing bacteria?
Resists immune mechanisms that allows them to travel to the CNS
What is the function of the fimbrae/pilli of the meningitis-causing bacteria?
help colonize the CNS cells
What are the two main things that cause the damage with meningitis?
2. Immune response
What is the significance of the bacterial toxins?
Incude the production of cytokines
What is the function of the cytokines released?
Cause inflammation and edema in the CNS
What are the four common symptoms of meningitis?
3. Stiff neck
How do you diagnose meningitis? (3)
1. Gram stain CSF
3. Latex agglutination
What is the treatment for meningitis? What is this based on?
Examination of CSF, age, preexisting conditions
The majority of cases of bacterial meningitis occur in what population group?
infants and children
What is the most (and second most) common pathogen of bacterial meningitis?
1. Strep pneumonia
2. Neisseria meningitidis
What percent of meningitis are caused by Strep agalactiae?
What percent of meningitis are caused by listeria monocytogenes?
What percent of meningitis are caused by H/influenzae?
What percent of meningitis are caused by Strep pneumonia?
What percent of meningitis are caused by N.meningitidis?
Kids less than 2 month of age (or 2 yo) are have bacterial meningitis caused by what pathogen?
What are the four major causes of bacterial meningitis in neonates?
1. Strep agalactiae
3. Gram negative enterics
What is the gram stain and morph of strep pneumonia? Catalase?
Gram positive cocci, catalase negative
What is the hemolysis patterns seen in strep penumo? Is it optochin sensitive? bile?
Sensitive to bile and optochin
Who are more frequently colonized by strep pneumonia kids or adults?
What are the three virulence factors that strep pneumo produces to help them spread in the body?
1. IgA protease
How fast is the onset of pneumococcal meningitis?
How do you diagnose pneumococcal meningitis?
Gram stain CSF
What does the latex agglutination test detect in pneumococcal meningitis?
What is the treatment for meningitis?
Initially vanco with a cephalosporin
Later with more targeted
How do you prevent pneumococcal meningitis?
What does the vaccine against pneumococcal meningitis contain?
Purified capsular polysaccharide from 23 types of pneumococcus
Why is the vaccine for pneumococcal meningitis not effective in children?
They have a problem developing antibodies to polysaccharides
What are the recommendations for the PPV vaccine?
Adults >65 yo
Persons >2 with chronic illness or likely exposure
What is PCV13 used in the pneumococcal vaccine?
Pneumococcal polysaccharide conjugated to nontoxic diphtheria toxin
What is the gram stain and morph of Neisseria meningititidis? (**key shape**)
Gram negative diplococci with **coffee bean appearance**
What are the two virulence factors for N.Meningitidis?
Coffee/kidney bean appearing bacteria = ?
How do you differentiate between N. Meningitidis vs gonorrhea?
Oxidizes both glucose and maltose
Is N. Meningitidis oxidase positive? Catalase?
What type of agar is needed for N. Meningitidis?
Do we have vaccines against N. Meningitidis?
Four of the five common ones
How is N. Meningitidis transmitted?
Coughs, secretions etc
What are the serotypes of N. meningitidis most often causes disease? (5) Which one do we not have a vaccine against?
2. B** no vaccine
What are the significant sequelae of N. Meningitidis infections?
What are the symptoms of meningococcal disease besides HA, stiff neck? (3)
Abrupt fever, hypotension, rash
How do you diagnose Meningococcal meningitis?
1. gram stain CSF
2. Antigen detection in CSF
What percent of patients with only bacteremia caused by meningococcal have detectable organisms in blood smears?
What is the treatment for meningococcal meningitis? (initially vs confirmed Meningococcal)
Penicillin if confirmed Meningococcal disease
What are the two types of vaccine against meningococcal disease? Which is actually used?
tetravalent polysaccharide only used for immune suppressed
(MCV4) Tetravalent polysaccharide conjugate vaccine = actually used
How many doses of the vaccine against meningoccal disease ?
one dose in 2-5 years if indicated
What is the conjugated polysaccharide that the meningococcal vaccine is conjugated to?
Diptheria toxin subunit
Which type of meningitis displays decreased glucose levels in the CSF: bacterial or viral?
Which type of meningitis displays increased protein levels in the CSF: bacterial or viral?
Which type of meningitis displays increased pressure in the CSF: bacterial or viral?
Which type of meningitis displays increased levels of mom/lymphocytes: bacterial or viral?
Which type of meningitis displays increased levels PMNs: bacterial or viral?
If a pt presents with meningitis, without knowing anything else, what is the most likely cause of it? What is it's a kid <2 yo (or months
GBS for kiddos
What is the gram stain and morphology of listeria?
Gram positive rod
What is the gram stain and morphology of HiB?
Gram negative rod
What groups of people is Listeria a major factor for meningitis?
Very young and old
Bile test is used to differentiate between what pathogens?
Strep and enterococcus
What bacteria need chocolate agar?