causes of, and risk factors for meningitis

see also:

• meningitis
• eosinophilic meningitis - eosinophils predominate the CSF

• Group B streptococcus,
• E. coli and other Gram-negative organisms (usually from UTI source)
• Listeria monocytogenes,
• S. pneumoniae,
• N. meningitidis
• Haemophilus influenzae type b.

• pneumococcus
• meningococcus
• Haemophilus influenzae type b (Hib uncommon after age 6 and in those vaccinated for Hib).

• Strept. pneumoniae
• Listeria monocytogenes / Listeriosis
• H influenzae - esp. alcoholics
• cryptococcal
• tuberculosis (TB)

• pneumococcus (if CSF leak is present)
• H influenzae (if CSF leak)
• Staphylococcus aureus
• coliforms
• Pseudomonas aeruginosa.

• Staphylococcus epidermidis
• S aureus
• coliforms
• Propionibacterium acnes
• diphtheroids (rare).

• cryptococcal
• tuberculosis (TB)
• syphilis
• HIV aseptic meningitis
• Listeria
• H influenzae

• ie. pleocytosis but no microrganisms seen on CSF
• viruses:
  • enteroviruses
    • account for 90% of aseptic meningitis cases
    • include echovirus, Coxsachie A/B, enterovirus 68-71
  • Herpes simplex virus (HSV)
    • accounts for 0.5-3% of cases
    • HSV-1 tends to cause encephalitis whilst HSV-2 tends to cause meningitis(emedicine))
  • lymphocytic choriomeningitis virus (LCM)
  • HIV / AIDS
  • other viruses particularly in the immunocompromised - varicella, EBV / glandular fever / infectious mononucleosis, cytomegalovirus (CMV), hhv 6/7, paramyxovirus, mumps, measles, rubella, togavirus, flavivirus, the various encephalitis viruses, rabies, polio, etc.
• clinically important bacteria:
  • partially treated bacterial meningitis
  • leptospirosis
  • brucellosis
  • rickettsia
  • Erhlichia
  • Mycoplasma pneumoniae
  • LymeDisease
  • syphilis
  • [tb]]
  • Nocardia
• parasites:
  • N fowleri
  • Acanthamoeba
  • Balamuthia
  • angiostrongyliasis - rarely, but most common cause of eosinophilic meningitis in SE Asia
  • G spinigerum
  • Baylisascaris procyonis
  • S stercolaris
  • Taenia solium (cysticercosis)
• fungi:
  • cryptococcal
  • C immitus
  • Blastomyces dermatitidis
  • H capsulatum
  • Candida
  • Aspergillus
• drug-induced:
  • non-steroidal anti-inflammatory drugs (NSAIDs)
  • metronidazole
  • iv immunoglobulin

• usually caused by Herpes simplex virus (HSV) (esp. HSV-2) but may be causd by varicella-zoster virus (chickenpox/shingles)

• clinically important bacteria:
  • tuberculosis (TB)
  • LymeDisease
  • syphilis
  • Nocardia
  • brucellosis
  • Francisella
  • Actinomyces
• parasites:
  • N fowleri
  • Acanthamoeba
  • angiostrongyliasis - rarely, but most common cause of eosinophilic meningitis in SE Asia
  • G spinigerum
  • Baylisascaris procyonis
  • S stercolaris
  • schistosomiasis
  • echinococcosis (hydatids)
• fungi:
  • cryptococcal
  • C immitus
  • Blastomyces dermatitidis
  • H capsulatum
  • Candida
  • Aspergillus
  • Sporothrix

• Hyposplenism
• Hypogammaglobulinemia
• Multiple myeloma
• Glucocorticoid treatment
• Defective complement (C1-C4)
• Diabetes mellitus
• Renal insufficiency
• Alcoholism
• Malnutrition
• Chronic liver disease

• unvaccinated children
• Paranasal sinusitis
• Otitis media
• Alcoholism
• CSF leak following head trauma
• Functional or anatomic asplenia
• Hypogammaglobulinemia

• neonates born to mothers with Group B Strep +ve in vagina
• Diabetes mellitus
• Pregnancy
• Alcoholism
• Hepatic failure
• Renal failure
• Corticosteroid treatment

• Pregnant women
• Infants esp. under 3 months age
• Elderly(>60 y)
• alcoholism
• immunosuppressed (eg, steroid use, transplant recipients, patients with acquired immunodeficiency syndrome [AIDS])
• chronic liver or renal disease
• diabetes
• iron-overload conditions (eg, hemochromatosis or transfusion-induced iron overload)

• Neurosurgical procedures or intracranial manipulation
• Old age
• Immunosuppression
• High-grade gram-negative bacillary bacteremia
• Disseminated hyperinfected strongyloidiasis