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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 - PowerPoint PPT Presentation
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Infections of the nervous systemDr,kibruyisfaw
oct, 2012Areas to be learned
Acute meningitis
Acute Bacterial MeningitisDef. bacterial infection of the subarachnoid spaceMajor presenting feature
Rapidly developing headache, fever, meningism and photophobiaPhysical exam
Nuchal rigidity, Kernig’s sign, Brudzinsk’ sign
Your immediate taskBacterial? Viral? Tuberculous?
Acute Bacterial meningitisMicrobiology/Causes
Neonates E. coli, GBS, P. mirabilis, L. monocytogenes, Pseudomonas
Children< 5y. N. mening. S pneumoniaeH. Influenzae
Older children and adults < 50 N. mening. and S.pneumo
Adults >50 S. pneumo, G- enteric bacilli,L. mono
Viral/ Aseptic/ MeningitisEnteroviruses, Mumps, Arboviruses,
HIV,HSV-2, HZV, AdenovirusesTuberculous 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—500-2000, protein increased, glucose reduced, g/stain—usually pos, wbc--neutrophilia
Viral/Aseptic/ meningitisAcute<2 days, not toxic , fully conscious, CSF– clear, cells-5-1000—lymph, protein normal or modest rise, glucose normal, g/stain neg, wbc normal
Tuberculous meningitisSub 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 diffBlood culturesLP—CSF G/stain, AFB, biochemistry, CSF culture, india ink, cryptococcal antigen, fungal culture, PCR—HSV, VZV,enteroviral, cytology, viral culture,viral serologyImaging—CXR, CT, MRI
DiagnosisBacterial Typical CSF picture CSF G/stain, culture, antigen detection CSF/bloodViral 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 treatmentABM = life threatening = emergencyKey= early dx. And rx.LP in all cases unless papilloedema or neurologic deficit = b/culture and empiric abx
Indications for empiric antibioticsLP cannot be doneIll or toxicPetechial rashesLP—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 therapyCSF = lymphocytic, protein raised,
glucose reduced, tests for AFB/fungal negative --- tbc still likely –antitbc + for L. mo
Specific infectionsMeningococcal meningitis and septicemiaEpidemiology
1963--- Meningitis belt b/n latitudes 4 and 16 north w/300-1100ml 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 epidemicDry season – groups A C W135
Organism in nasopharnyx, highest carriage in 15-19 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 presentationRapidly progressive shockDIC---- bleeding into and dysfunctions of
many organs including adrenals =Wterhouse Friederichsen syndrome
Purpuric rashIP—1-3 days
Clinical featuresAbrupt –fever, vomiting, headache,
irritability, restlessness --signs of meningitis or
Fulminant septicemia – toxicity, drowsiness and shock
Petechial or purpuric rash = 2/3
ComplicationsWaterhouse-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
DiagnosisHigh index of suspicionCSF studies
TreatmentPreferred= ceftriaxone 2 g q24h or
cefotaxime 2 g q4-6hx7-10 daysAlternatives= CAF 4-6 g/dx7-10 daysSteroid= dexamethasone 10 mg iv q6hx4
days
PreventionRespiratory isolation x 24hChemoprophylaxis Household or intimate contact,
med. PersonnelRif. 600 mg bid x 2 daysCipro 500mg x1 doseCeftriaxone 250mg im x1 dose
ImmunoprophylaxisConjugate vaccine
Target population= all children at 11-12 years
Anyone > 2 years w/risk = college students, military recruits, asplenia
Polysaccharide vaccine A C Y W135
For outbreaks, age>65