BACTERIAL MENINGITIS (BM)

BACTERIAL MENINGITIS (BM)

Young children who lost Ab from mother
Adolescents not previously encountered infecting serotype (no type-specific immunity)

Incubation 1-3d
Sore throat, headache, drowsiness, meningitis signs (fever, irritability, neck stiffness)
Haemorrhagic skin rash with petechiae (assoc septicaemia)
35% have fulminant septicaemia (DIC, endotoxaemia, shock, renal failure - Addisonian crisis if most severe - bleeding into brain and adrenal glands - Waterhouse-Friderichsen syndrome)
Untreated meningococcal meningitis 100% (10% is treated)
Dx - (apporpriate ABX, prophylaxis of contacts), preliminary results whtin 1h of CSF receipt in lab, culture of CSF/blood results 24h later (serology no use = infection too acute for Ab response to be detectable)
Empiric ABX = penicillin, ampicillin
Kissing contacts = Rifampicin chemoprophylaxis for 2-3d (penicillin not used for prophylaxis b/c odes not eliminate NP carriage)
Resistance to sulphonamides \ no longer used

Unencapsulated strains common, in throat of most healthy people
Capsulates type b (commonly RS infants + young children) occasionally invades blood and reaches meninges

Maternal Ab protecin - not > 3-4m (window of susceptibility until child produces own Ab)
Virulence factors - capsule, IgA protease, pili, endotoxin, other membrane proteins
Clinical featyres

Incubation 5-6d
Onset more insidiou than meningococcal or penumococcal meningitis
Less fatal, 10% incidence of serious sequelae (hearing loss, delayed lang development, MT, seizures)
Dx - org difficult to see in Gram-stain (esp if in small numbers)
H influenzae vaccine (Hib) suitable for > 6mo
Close contacts = Rifampicin prophylaxis

Strep pneumoniae
Virulence - capsule, IgA protease
Capsulate Gram +ve coccus
Throats of many normal individuals
Invasion of blood and meninges ® < 2yo, elderly, sickle cell disease, debilitated, splenectomised, following head trauma
More than 85 capsular types of Strep pneumoniae
Clinical features - acute onset after pneumonia and/or septicaemia in elderly
Polysaccharide (23-valent) vaccine - effectiveness NK (not < 2yo)

CSF	Cells / m L	Protein (mg/dL)	Glucose (mg/dL)	Causes
N	0-5	15-45	45-85	-
Septic (purulent meningitis)	200-20,000 Neutrophils	High (>100)	< 45	Bacteria Amoebae Abscess
Aspective* meningitis Meningoencephalitis	100-1,000 Mononuclear	Mod high (50-100)	Normal**	Virus TB Leptospira Fungi Abscess Prev-Tx bact
* Aseptic = CSF sterile on regular bac culture ** Low (<45) in TB, fungi, leptospira

Non-Viral Meningitis
Pathogen	Tx	Prevention
N meningitidis	Penicillin Chloramphenicol	Rifampicin (close contacts) Polysacc vaccine
H influenzae	Ampicillin (empirical) Ceftriaxone (Chlormaphen)	Polysacc vaccine (Hib) vs type b
Strep pneumoniae	Penillin Ceftriaxone (Cholramphen)	Tx OM + resp infection Polyvalent (23 serotype) polysacc vaccine
E Coli (group B strep)	Gentamicin + Cefotaxime Cefriaxone (Chloramphenic)	NO VACCINE
Listeria monocytogenes	Penicillin/Ampicillin + Gentamicin	NO VACCINE
M TB	Isoniazid, Rifampicin, Pyraxinamide ± Streptomycin	BCG vaccination Isoniazid (reco USA)
Cryptococcus neoformans	Amphtericin B + flucytosine	NO VACCINE

BACT MENINGITIS
Pathogen	Host (Pt)	Clinical	Mortality (Tx)	Sequelae (Tx)
N meningitidis	Children / Adole	Acute (6-24h) Skin rash	7-10	<1
H influenzae	< 5yo	Less acute (1-2d)	5	9
S pneumoniae	<2yo + elderly	Acute after pnuem / septicaemia	20-30	15-20