PYOGENIC MENINGITIS

Dr Babalola T.EDept of Paediatrics and Child healthOAUTHCIle -Ife

OUTLINE• Introduction• Epidemiology• Aetiology• Predisposing factors• Pathogenesis• Pathology/Pathophysiology• Clinical manifestations• Diagnosis• Treatment• Complications• Prognosis• Prevention/Prophylaxis• Conclusion

INTRODUCTION

• Pyogenic meningitis implies an inflammation of the leptomeninges.

• It is a potentially fatal infection that can affect any age group.

• It is associated with significant morbidity and mortality.

DEFINITION.

• Inflammation of the meninges which may be caused by bacteria, viruses, fungi, protozoa or chemicals.

• Commonest form seen is bacterial meningitis- PYOGENIC Meningitis.

• Peak age in infancy. 95% of cases of meningitis occur <5yr.

• Higher incidence in pts with impaired splenic function- HbSS, Nephrotic syndrome, congenital asplenia, post-splenectomy, as a result of increased susceptibility to infections by encapsulated organisms e.g. H.flu, Strept pneumo

EPIDEMIOLOGY

• Up to About 80-95% of cases occur in children <5 yrs.• 25% of babies with neonatal sepsis may have meningitis.• Accounts for about 0.9-5.1% of emergency room

admissions.• Affects males more than females.• Incidence has reduced in developed countries due to

vaccine use.

AETIOLOGY• Neonates : E. coli is commonest then GBS particularly in

the first week. Later, klebsiella spp. P. aeuroginosa, L. monocytogenes, proteus spp.

• Beyond the neonatal group 72-96% of cases are caused by H.influenza type b, S. pnemoniae and N. meningitidis.

• For infants 2-3 months , organisms from both groups could be implicated.

AETIOLOGY (contd)

• H.influenza, Gram neg. pleomorphic coccobacillus.

• Affects children 3mnths-4yrs

• Infection can occur in epidemics.

AETIOLOGY (contd)

• S.pneumonia: Gram pos. cocci.

• Incidence increases after 4yrs.

• Commoner in the south.• Has various serotypes.

AETIOLOGY (contd)• N.meningitidis: Gram neg intracellulaar diplococcus.

• Cause of infection more in the North.

• Can occur sporadically and in epidemics.

• Epidemics occur in meningitic belt 5-15N

PREDISPOSING / RISK FACTORS• In neonates: maternal infections, Chorioamnionitis, Spina

bifida, LBW babies• Overcrowding,• Male gender• Splenic Dysfunction• Otitis media, mastoiditis, basal skull fracture• Abnormalities of the immune system• Burns

Pathogens vary with age.

Pyogenic meningitis

NEONATES

G -ve BacilliGrp B StreptococcusStaph aureusLysteria monocytogenes

1-2 MONTHS Org in neonates +Org in age 3mo- 12yr

3mo – 12yrsHaemophilus influenzaeStreptococcus pneumoniaeNeisseria meningitidis

Pathogenesis

URTI

Bacteraemia

Invasion of the meninges

Meningitis

Sequele

Release of acute phase reactantsIL-1, TNF, Cytokines

Contiguous spread: Otitis mediaMastoditisPen. Head injuryMyelomeningocoele

Septicaemia

Penetration of BBB

PATHOGENESIS• Usually results from haematogenous spread.• May also follow direct inoculation • Capsules help resist phagocytosis• Reduced concentration of complement and antibodies in

CSF encourages proliferation• Inflammatory response occurs with production of

cytokines and subsequent alteration of BBB.

PATHOLOGY/PATHOPHYSIOLOGY• Purulent exudate within the meninges which may spread

to the ventricles.• Cerebral infarction may be due to vascular occlusion• Inflammation of spinal and cranial nerves• Raised ICP due to a combination of vasogenic, cytotoxic

and interstitial oedema, SIADH maybe a contributing factor.

PATHOPHYSIOLOGY (contd)

• Raised CSF protein due to increased vascular permeability.• Hypoglychorrachia due to decreased glucose transport by

cerebral tissues

PATHOLOGY

CLINICAL FEATURES

Non-specific:

FeverLethargyVomitingIrritabilityRefusal of feedsCoughCattarrh

Specific:

Convulsion- 20-30%Bulging AFNeck painPhotophobiaHeadacheComa+ Features of raised ICP

Features of Raised ICP: Bulging AF Abnormal pupils:unequalVomiting dilatedPapilloedemaHypertensionBradycardiaAbn. Respiration- apnoea,hyperventilation

CLINICAL MANIFESTATIONS• High index of suspicion needed particularly for neonates and

younger children.• There are no specific sign or symptoms attributable to

meningitis in neonates• Up to a 3rd of patients < 2yrs don’t show typical signs and

symptoms.• May be insidious or fulminant in presentation

CLINICAL MANIFESTATIONS• A preceding history of URTI or gastroenteritis may be

present.• Seizures are present in up to 30% prior admission and up

to 75% convulse during the illness.• Focal neurological signs are present in 7-15% SP >NM

Signs of meningeal irritation

Unusual finding in infants & young children. Diagnosis of meningitis in this age group thus requires a high index of suspicion.

Neck stiffness +ve Kerning's sign +ve Brudzinski sign

Diagnosis Lumbar Puncture mandatory. CSF analysis shows- o Pleocytosis with preponderance of neutrophilso Elevated CSF protein contento Reduced CSF: Blood sugar ratio (Hypoglycorrhachia)o +/- Orgs. on Gram staino +/- Culture.

DIAGNOSIS • Lumbar puncture• Blood culture• PCV• E/U• FBC• RBS• CT Scan• Rapid diagnostic tests: CIE, ELISA, Limulus lysate

Contra-indications to LP

• 1. Raised ICP• 2.Thrombocytopaenia• 3. Coagulopathy• 4. Infection of overlying skin at LP site• 5. Very ill patients with imminent cardio respiratory collapse

•

•

Typical CSF picture in the various forms of Meningitis

Normal CSF

PyogenicMeningitis

PartiallyTreated

ViralMeningit

TBMeningit

Appearance

ClearColourless

Purulent Turbid,Hazy

TurbidHazy

Clear Colourless

Xanthochromic, clear

WBC <5/mm3 Increased++N >L

Increased+ L>N

Increased+ L >N

Increased L>N

RBC nil nil nil + / - nil

Protein 10-40mg/dl Increased + +

Increased + / ++

Increased +

Increased +++

CSF: BSRatio

½ - 2/3 < 1/2 <1/2 Normal <1/2

GramStain

No org seen

+ /- -ve -ve -ve

TREATMENT

Parenteral Antibiotic Therapy is the treatment of choice. Drugs must be given IV.

NEONATES - Combination of a 3rd Generation Cephalosporin & an Aminoglycoside. IV Ceftriaxone or Cefotaxime or Ceftazidime + IM Gentamycin or IV Amikacin Lysteria monocytogenes- IV AMPICILLIN

INFANTS 1-2 MO - Treat as Neonate.

Age >2mo - IV Crystalline Penicillin 0.04MU/kg/D + IV Chloramphenicol 100mg/kg/D

Steroid Therapy- Controversial. IV Dexamethasone 0.15mg/kg 6hrly X 48hr. First dose

must be given at least 30min before 1st dose of antibiotic.

Duration of antibiotic therapy depends on the causative organism:

• G-ve bacilli - 21days• N.meningitidis - 5-7days• H.flu - 7-10days• Strept pneumo - 10-14days

• Neonatal meningitis – 21 days

o SUPPORTIVE THERAPY - ABC of resuscitation - Anticonvulsants - N-G Tube feeding - Control Raised ICP- Mannitol, Hypervent - Frequent Turning - Strict input / output monitoring

DIFFERENTIAL DIAGNOSIS• Cerebral malaria• TB meningitis• Aseptic meningitis• Encephalitis• Lead encephalopathy• CNS spread of Malignancies• Brain tumors• Causes of meningism

COMPLICATIONS• Deafness - commonest comp. of meningitis• Subdural effusion• SIADH• Visual impairment• Hydrocephalus- usually non-obstructive type• Seizure disorder• Speech defects• Mental retardation• Cerebral palsy• Ataxia

TREATMENT• Standard duration of treatment: Hib 7-10 days, NM-- 7 days,

SP 10 days GNB- 3 weeks• Role of corticosteroids: decreased duration o fever, CSF

protein, frequency of seizures, and frequency of hemiparesis and hearing deficits.

TREATMENT

• Supportive care:• Regular monitoring of the vital signs• Control of seizures• Fluid restriction• Treatment of raised intracranial pressure• Treatment of shock

COMPLICATIONS• Acute complications: seizures , raised ICP, CN palsies

• Subdural effusion• SIADH• Hydrocephalus • Neurologic deficits• Persistent or prolonged fever• Athritis or pericarditis• Long term sequelae

PROGNOSIS

• Poorer in neonates• Mortality is higher in SP>NM>Hib• Delayed diagnosis and inadequate treatment• Delayed CSF sterilization• Seizures after the 4th day of therapy

Prevention

IMMUNISATION Hib vaccine Conjugate pneumovax CSM Vaccine- given during epidemics

Good hygiene and hand washing practices in neonatal units.

CHEMOPROPHYLAXIS P.O. Rifampicin- given to household & close contacts of patients

with H.flu or meningococcal meningitis. rifampin 10 mg/kg/dose every 12 hr (maximum dose of 600 mg) for 2

days as soon as possible after identification of a case of suspected meningococcal meningitis or sepsis

CONCLUSION• Pyogenic meningitis still causes significant morbidity and mortality in our environment and the incidence can be reduced by improved social conditions.

• Though the use of vaccines has reduced the incidence in developed countries when it does occur it si still associated with significant morbidity. Ways of improving the outcome with regards to sequelae need to be sought.