DR LNR GONZÁLEZKHC,RSA

ACUTE BACTERIAL MENINGITIS

Objectives

DefinitionEpidemiologyClinical PresentationDiagnosisTreatmentPrognosis

Meninges

Meninges

Definition

Bacterial meningitis is an acute purulent infection within the subarachnoid space. It is associated with a CNS inflammatory reaction that may result in decreased consciousness, seizures, raised intracranial pressure (ICP), and stroke. The meninges, the subarachnoid space, and the brain parenchyma are all frequently involved in the inflammatory reaction (meningoencephalitis).

Epidemiology

Adult to age 60S. pneumoniae (51%-60%)N meningitidis (20-37%)L. monocytogenes (4-6%)H. influenzae, Streptococci, S.

aureus, and gram-neg bacilli

Quagliarello, Vincent. Epidemiology of bacterial meningitis in adults. Uptodate. 26 May 2009.

Epidemiology

Adults over age 60 S. pneumoniae (70%)L. monocytogenes (20%)N. meningitidis (3-4%)Group b strep (3-4%)H. influenzae (3-4%)

Quaglierello, Vincent . Epidemiology of bacterial meningitis in adults. Uptodate. 26 May 2009.

Predisposing Factors

Recent exposure Recent respiratory or otic infectionRecent travel to endemic areasRecent head traumaImmunosuppression

Asplenia Complement deficiency Corticosteroid excess HIV Infection

Kaplan, Sheldon L. Epidemiology, clinical features and diagnosis of acute meningitis in children. UpToDate. 27 May 2009.

Clinical Features

Classic TriadFever (77%-95%)Nuchal Rigidity (83%-88%)Change in Mental Status (69-78%)

Headache (87%)Severe and generalized

Van de Beek D et al. Clinical features and prognostic features in adults with bacterial meningitis. NEJM. 28 October 2004.

Other Clinical Features

Symptoms lasting < 24 hours (48%)Focal Neurologic Deficit (33%)Rash (26%)

Petechiae Palpable purpura

Coma (14%)Seizure (5%)

Van de Beek D et al. Clinical features and prognostic features in adults with bacterial meningitis. NEJM. 28 October 2004.

Examination

Exam for signs of infectionKernig’s SignBrudzinski’s sign Glasgow Coma Scale

Kaplan, Sheldon L. Epidemiology, clinical features and diagnosis of acute meningitis in children. UpToDate. 27 May 2009.

Examination

Kernig’s Sign

Examination

Brudzinski’s Sign

Possible Complications NeurologicalSeizures (15-30%)Focal neurologic deficit

(20-50%)CN Palsies (III, VI, VII,

VIII) 5-11%Sensorineural hearing

loss (12-14%)Hemiparesis (4-13%)Intellectual impairment

SystemicSeptic shockDICARDSSeptic or reactive

arthritis

Tunkel, Allan R. Clinical Features and diagnosis of acute bacterial meningitis in adults. UpToDate. 16 June 2009.

Investigations

Leukocytosis or leukopeniaPossible thrombocytopenia+Blood cultures (40-75%)Chest RadiographyCSF studies

Kaplan, Sheldon L. Epidemiology, clinical features and diagnosis of acute meningitis in children. UpToDate. 27 May 2009.

CT Scan

Immunocompromised? New onset seizure Papilledema Abnormal level of consciousness Focal neurological deficit

Get Treatment with ab’s/steroids

Tunkel, Allan R. et al. Practice guidelines for the management of bacterial meningitis. Clin Infect Dis. 1 November 2004

  Reference Range

Constituent SI Units Conventional Units

  Chloride 116–122 mmol/L 116–122 meq/L

Glucose 2.22–3.89 mmol/L 40–70 mg/dL

Total protein 0.15–0.5 g/L 15–50 mg/dL

CSF pressure   50–180 mmH2O

 

CSF volume (adult) ~150 mL

Red blood cells 0 0

Leukocytes    

  Total 0–5 mononuclear cells per  L 0–5 mononuclear cells per mm3

 

  Differential    

    Lymphocytes 60–70%  

    Monocytes 30–50%  

    Neutrophils None  

Cause AppearancePolymorphonuclear

cellsLymphocytes Protein Glucose

Pyogenic bacterial meningitis

Yellowish, turbid

Markedly increased>1000. More than 85% of total number of white cells.

Slightly increased or Normal

Markedly increased Markedly Decreased

Viral meningitisClear fluid, can be hemorrhagic in HV

Increased Polys have been described in HV.

Increased<100. More than 85% of total number of white cells.

Slightly increase or Normal

Normal

Tuberculous meningitis

Initially clear then Turbid and viscous

Can be increased in early stages.<500There are descriptions of TBM with no cells in CSF@ initial stages.

Markedly increase>100. More than 85% of total number of white cells.

Increased>2g

Decreased

Fungal meningitisClear or Turbid and viscous

Less than 25% of total number of white cells

Markedly increased. More than 85% of total number of white cells.Cells can be absent in cryptococcal infection.

Slightly increased or Normal

Normal or decreased

Gram Stain

Gram + Diplococci (S. pneumo)Gram – Diplococci (N. meningiditis)Gram + Bacilli (Listeria)Gram – bacilli

Tunkel, Allan R. et al. Practice guidelines for the management of bacterial meningitis. Clin Infect Dis. 1 November 2004

Treatment

Start empirical therapy and then examine CSF within 30 minutes.If focal neurological deficit is present, give empiric treatment, do a CT Brain , then decide on LP.

Frequent aetiological agents: S. pneumonia,N. meningitidis,H. influenzae

Sugested Empiric Regimes:Ceftriaxone 2g IV q 12 h or cefotaxime 2g q 4h IV x 10-14

days.Dexametasone 10mg IV q 6h x 4 days.Give with or just

before 1st dose of antibiotics.

Treatment

Alternative Drugs;Meropenem 2g IV q 8 h x 10-14 days.

Penicillin Allergy:Chloramphenicol 50mg/kg/d IVI div q 6h

+TMP/SMX 15-20mg(TMP)/kg/d div q6h+ vancomycin 500 mg q 6h IV x 10-14 days

Treatment

Penicillin g 24 mu /day remains the antibiotic of choice for meningococcal meningitis caused by susceptible strains. A 7-day course of intravenous antibiotic therapy is adequate for uncomplicated meningococcal meningitis.

Duration of antimicrobial therapy forbacterial meningitis based on isolated pathogen

A 2-week course of intravenous antimicrobial therapy is recommended for pneumococcal meningitis.

L. monocytogenes, meningitis due to this organism is treated with ampicillin 2g q4h for at least 3 weeks.

A 3-week course of intravenous antibiotic therapy is recommended for meningitis due to gram-negative bacilli.

Treatment

Non-Typhoidal Salmonellas (common in HIV infection) treatment must be commenced with a combination of Ceftriaxone 2g q 12 h IV + Ciprofloxacin 750mg q 12h IV, three weeks of IV antibiotics is recommended.

Post neuro surgery or post head trauma:

Frequent aetiological agents:S. pneumonia, S. aureous, P. aeruginosa, coliforms.

Sugested Treatment: Vancomycin 1g q 6-12h IV (until known not MRSA)+ceftazidime 2g q 8h IV.

Alternative Treatment :Meropenem 1g q 8h IV+ vancomycin 1g q6h IV(until known not MRSA)

If S.pneumona is identified switch to ceftriaxone/cefotaxime.

Prognosis

Mortality is 3–7% for meningitis caused by H. influenzae, N. meningitidis, or group B streptococci.

15% for that due to L. monocytogenes.

20% for S. pneumoniae.

Prognosis

The risk of death from bacterial meningitis increases with

1-Decreased level of consciousness on admission.

2- Onset of seizures within 24 h of admission.

3- Signs of increased ICP. 4- Age >50.5-The presence of comorbid conditions

including shock and/or the need for mechanical ventilation.

6- Delay in the initiation of treatment

Prognosis

Decreased CSF glucose concentration [<2.2 mmol/L (<40 mg/dL)] and markedly increased CSF protein concentration [>3 g/L (>300 mg/dL)] have been predictive of increased mortality and poorer outcomes in some series.

Moderate or severe sequelae occur in ~25% of survivors, although the exact incidence varies with the infecting organism.

Common sequelae include decreased intellectual function, memory impairment, seizures, hearing loss and dizziness, and gait disturbances.

More on Central Nervous System infections available on request.

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