Acute Bacterial Meningitis

Question 0

Streptococcus pneumonia

Answer 0

-Gr+ coccus, usually diplocoocci or in short chains
-found in oropharynx and nasopharynx
-humans are only reservoir
-common during winter and early spring
Lab
-Cat-
-Alpha-hemolytic (green) on blood agar
-also grows on chocolate agar
-optochin-sensitive
-bile-soluble
Diseases
-Meningitis (all age groups except 0-4 weeks)
-Pneumonia
Virulence
-polysaccharid capsule
-IgA protease
-Pneumolysin - creates pores, cell lysis
Diagnosis
-*latex agglutination test
Tx
-15% are *resistant to penicillin
-vancomycin+ceftriazone, empiric tx

Question 1

Neisseria meningitides

Answer 1

-Gr- diplococci
-aka meningococcus
-strictly human pathogen
-nasopharynx
-peak in cold dry months
-pt can die in <1 day
Lab
-grows on blood and chocolate agar
-cat+ ox+
-ferments glucose mad maltose (not sucrose or lactose)
Diseases
-acute purulent meningitis (most common)(all age groups except 0-4 wks)
Virulence
-IgA protease
-pili & OMPS
-polysaccharide capsule (most imp serogroups: A, B,C, W-135, Y)
-*LOS
At risk
-ppl with *complement deficiency
-ppl w/ *splenia (absent or defective spleen)
-travelers to sub-saharan africa
Tx
-3rd gen. cephalosporins
-meningococcal polysaccharide vaccine
-meningococcal conjugate vaccine (better)
-both cover serogroups A, C, Y, and W-135

Question 2

Streptococcus agalactiae

Answer 2

-spherical, Gr+ cocci in chains
-has group B Lancefield antigen=Group B strep (GBS)
-asymptomatically colonizes lower GI and GU tracts of women
Lab
-Cat-
-Beta-hemolytic
-bacitracin-resistant
-CAMP+
-Hippurate hydrolysis
Diseases
-Meningitis (rarely)
-“baby strep” (ages 0-12 wks old)
-neonatal GBS disease
Virulence
-polysaccharide capsule
-pili
At risk
-blacks

Question 3

Listeria monocytogenes

Answer 3

-short, Gr+ rods, alone, in pairs, or short chains
-no capsule
-in soil, rotten vegetables, all kinds of food, dust
-sporadic & year round, but summer more common
Lab
-weak Beta-hemolysis on blood agar
-cat+
-CAMP+
-grows at refrigerated temp (4 C)
Virulence
-facultative intracellular pathogen
-internalin - used to enter via endocytotic vacuole
-LLO - creates pores to get out
-ActA - movement engine
-Actin comet tails
Diseases
-healthy adults
-gastroenteritis
-pregnant women
-miscarriage, still birth, premature delivery
-meningitis or meningoencephalitis with septicemia in newborns (0-4 wks old)
-immunocompromised and elderly
-septicemia
-meningitis
Diagnosis
-“tumbling motility” is diagnostic in CSF
Tx
-Pregnant women
-ampicillin
-neonates and severe listeriosis
-gentamicin