Infections of the nervous system Dr,kibruyisfaw oct, 2012 Areas to be learned Acute meningitis

Acute Bacterial Meningitis Def. bacterial infection of the subarachnoid space Major presenting feature Rapidly developing headache, fever, meningism and photophobia Physical exam Nuchal rigidity, Kernig’s sign, Brudzinsk’ sign Your immediate task Bacterial? Viral? Tuberculous?

Acute Bacterial meningitis Microbiology/Causes Neonates E. coli, GBS, P. mirabilis, L. monocytogenes, Pseudomonas Children< 5y. N. mening. S pneumoniae H. Influenzae Older children and adults < 50 N. mening. and S.pneumo Adults >50 S. pneumo, G- enteric bacilli, L. mono

Viral/ Aseptic/ Meningitis Enteroviruses, Mumps, Arboviruses, HIV,HSV-2, HZV, Adenoviruses Tuberculous meningitis Mycobacterium tuberculosis

How can you distinguish weather it is bacterial viral or tuberculosis ? Bacterial/pyogenic/ onset--- acute<2days, toxic and ill, drowsy, possible purpuric rash, CSF—turbid or opalescent, cells— , protein increased, glucose reduced, g/stain—usually pos, wbc-- neutrophilia

Viral/Aseptic/ meningitis Acute<2 days, not toxic, fully conscious, CSF– clear, cells —lymph, protein normal or modest rise, glucose normal, g/stain neg, wbc normal

Tuberculous meningitis Sub acute, not toxic, alertness may be depressed, CSF—clear, may form cobweb on standing, cells—50-400, lymphocytes, protein increased, glucose reduced, g/stain neg, wbc- normal

What diagnostic tests? WBC and diff Blood cultures LP—CSF G/stain, AFB, biochemistry, CSF culture, india ink, cryptococcal antigen, fungal culture, PCR—HSV, VZV,enteroviral, cytology, viral culture,viral serology Imaging—CXR, CT, MRI

Diagnosis Bacterial Typical CSF picture CSF G/stain, culture, antigen detection CSF/blood Viral Enterovirus—in faeces, CSF, throat swab Mumps---CSF, urine, serology Arbovirus—serology, PCR of CSF

Tuberculosis AFB in CSF smear, CSF PCR, CSF culture

Investigation and treatment ABM = life threatening = emergency Key= early dx. And rx. LP in all cases unless papilloedema or neurologic deficit = b/culture and empiric abx

Indications for empiric antibiotics LP cannot be done Ill or toxic Petechial rashes LP—turbid When to review therapy? Causative bacteria isolated

CSF guided action CSF = clear wait for lab. Results CSF = lymphocytic, normal biochemistry = probable viral meningitis – review likelihood other causes of similar CSF changes do virology tests CSF = lymphocytic, protein raised, glucose reduced, AFB or fungal tests positive – start appropriate therapy

CSF guided therapy CSF = lymphocytic, protein raised, glucose reduced, tests for AFB/fungal negative --- tbc still likely –antitbc + for L. mo

Specific infections Meningococcal meningitis and septicemia Epidemiology Meningitis belt b/n latitudes 4 and 16 north w/ ml annual rainfall south of Sahara Belt—high levels of endemicity w/ large superimposed epidemics ----Serogroup A = predominant

The only form of bact. Mening—epidemics Caused by N. meningitides G- intracellular diplococcus Pathogenic groups –A B C D X Y Z W135 Group B and C predominant in temperate areas The highest burden = Sub-Saharan Africa from Ethiopia to Senegal = meningitis belt Both endemic and epidemic Dry season – groups A C W135

Organism in nasopharnyx, highest carriage in years Transmission –droplet spread or direct contact w/ index case Overcrowding – Pathogenesis Colonization of nasopharyngeal mucosa— local invasion—bacteraemia—intravascular multiplication----- meningeal invasion – SAS inflammation

Or septicemic presentation Rapidly progressive shock DIC---- bleeding into and dysfunctions of many organs including adrenals =Wterhouse Friederichsen syndrome Purpuric rash IP—1-3 days

Clinical features Abrupt –fever, vomiting, headache, irritability, restlessness --signs of meningitis or Fulminant septicemia – toxicity, drowsiness and shock Petechial or purpuric rash = 2/3

Complications Waterhouse-Friederichsen syndrome= fulminant septicemia w/adrenal cortical failure Ischemia –tissue damage—loss of finger and/or toes Hydrocephalus, brain damage, subdural hemorrhage, brain abscess, deafness

Diagnosis High index of suspicion CSF studies

Treatment Preferred= ceftriaxone 2 g q24h or cefotaxime 2 g q4-6hx7-10 days Alternatives= CAF 4-6 g/dx7-10 days Steroid= dexamethasone 10 mg iv q6hx4 days

Prevention Respiratory isolation x 24h Chemoprophylaxis Household or intimate contact, med. Personnel Rif. 600 mg bid x 2 days Cipro 500mg x1 dose Ceftriaxone 250mg im x1 dose

Immunoprophylaxis Conjugate vaccine Target population= all children at years Anyone > 2 years w/risk = college students, military recruits, asplenia Polysaccharide vaccine A C Y W135 For outbreaks, age>65