Pyogenic meningitis Meningitis is defined as inflammation of membranes surrounding the brain and spinal cord Meningoencephalitis is inflammation of meninges and brain cortex pyogenic meningitis
pyogenic meningitis
Incidence and etiology Bacterial meningitis is commonest in infancy May result in death within hours of onset if not treated Responsible for 3% hospital admissions More frequent in infant males Any organism can cause meningitis Great risk during 6-12 months and 95% cases occur between 1month and 5years pyogenic meningitis
Causative agents for different ages pyogenic meningitis Age Causative agents 0 – 2 months Escherichia coli Group B streptococci Staphylococcus aureus Listeria monocytogenes 2months – 2 years Haemophilus influenzae type b Streptococcus pneumoniae Neisseria meningitides 2 years – 21 years Neisseria meningitides (serotypes A, B, C, Y and W 135) Streptococcus pneumoniae (serotype 1, 3, 6, 7, 14, 19, 21, 23) Haemophilus influenzae
Streptococcus pneumoniae
Pathogenesis Causative agent enter CNS via blood or direct invasion Anatomic or congenital defect can also cause invasion Inflammation of meninges initiated when cell elements of organism disrupt blood brain barrier Followed by outpouring of polymorphs and fibrin pyogenic meningitis
Release of cytokines and chemokines in CNS stimulated by bacteria Meninges become swollen, inflamed and covered in exudates Early in illness cerebral edema present and ventricles reduced in size Pressure on peripheral nerves may lead to motor or sensory deficit Communicating hydrocephalus due to adhesive thickening of arachnoid in basal cisterns pyogenic meningitis pathogenesis
Obstructive hydrocephalus due to fibrosis blocking aqueduct of sylvius or foraminas Affected cranial nerves cause deafness and vestibular problem Cerebral vessels and cranial nerves can be involved and may lead to permanent neurologic damage Cerebral atrophy by thrombosis of small cortical veins pyogenic meningitis pathogenesis
Inflammation involving veins crossing subdural space lead to increase in vascular permeability and loss of albumin into subdural space Hypoglycorhacia by decreased transport of glucose across the inflamed choroid plexus and increased use by host Seizures by electrolyte imbalance ultimately depolarization of neuronal membranes pyogenic meningitis pathogenesis
Clinical features Meningitis always must be considered in any young infant whose temperature is greater than 100.7°F (38.2°C) and who has no obvious site of infection pyogenic meningitis
Neonates and infants Gram negative organisms are commonly responsible Infective illness in mother, prolonged rupture of membranes or difficult delivery put the newborn at risk Premature infants have low level of antibodies Predisposing factor is spina bifida or dermal sinus pyogenic meningitis
Initial signs are subtle Fever occurs in 50% of cases Infant is ill looking and feeds poorly May develop vomiting, hypothermia, lethargy, convulsions Has bulging anterior fontanelle, head retraction and high pitch cry pyogenic meningitis neonates and infants
Older children Classic signs preceded by upper respiratory or GIT symptoms High grade fever, head ache and projectile vomiting Seizures are common Increased CSF pressure leads to bulging fontanelle and diastasis of sutures pyogenic meningitis
Neck stiffness, positive kerning's sign and brudzinski’s sign Cranial nerve palsies and papilledema Hemiplegia in cases late reported, ataxia may also be present Patient may be semi comatose or comatose Meningococcal meningitis is characterized by the presence features of Waterhouse Friderichsen syndrome pyogenic meningitis older children
Otitis media and mastoiditis is likely to lead streptococcal or pneumococcal meningitis Staphylococcal infection is likely following surgical procedures, skull fractures or skin infections If there is no specific sign between 6months – 2years then H. influenzae is the cause Onset of clinical signs is sudden in meningococcal and S. pneumoniae infection pyogenic meningitis in older children
Investigations Lumbar puncture CSF pressure should be noted, fundi checked for papilledema Xanthochromia due to jaundice, bilirubin from hemorrhage or increased protein If lumbar puncture is traumatic; one leukocyte per 700 RBC in CSF is subtracted and 1 additional mg protein is added in CSF protein for 800 RBC pyogenic meningitis
CSF glucose should be compared to blood glucose, CSF glucose is 2/3 of blood glucose In CSF of neonates normally there are up to 30 lymphocytes and 150mg/dl protein Gram stain is important to recognize the causative agent pyogenic meningitis investigations LP
pyogenic meningitis investigations LP CSF findings in various CNS disorders Conditon Color Leucocytes Protein mg/dl Glucose mg/dl Normal Clear 0 – 5 60 – 70% lymphocytes 20 – 45 >50 or 75% of blood glucose Acute bacterial meningitis Opalescent to purulent 100 – 20000 PMN predominate 100 – 500 <40 May be none Tuberculous meningitis Opalescent 10 – 2000 PMN early but lymphocyte later >50 <40 May be none Viral encephalitis Clear 5 – 500 Mostly lymphocytes PMN early 30 – 150 30 – 70
Contraindications for immediate LP Increased ICP especially with focal neurologic deficits Severe cardio pulmonary compromises Infection of skin overlying the site of LP Bleeding or clotting disorder pyogenic meningitis investigations LP
Recommendation for repeat LP at 24 – 36 hours All neonates Meningitis caused by S. pneumoniae and gram negative enteric bacilli Lack of cranial improvement in 24 – 36hours after therapy Prolonged or second fever Recurrent meningitis Immunocompromised patients pyogenic meningitis investigations LP
CSF culture The yield of CSF culture decreases soon after antibiotic therapy has been started. More sensitive technique, polymerase chain reaction may help to diagnose cases of bacterial meningitis in patients treated by antibiotics Blood culture 90% H. influenzae and 80% S. pneumoniae pyogenic meningitis investigations
Blood counts Total and differential leukocyte count; generally there is leucocytosis with predominant polymorphs X – ray chest To rule out TB and pneumonia CT scan pyogenic meningitis investigations
Indications for CT scan Newborn except for disease caused by listeria Prolonged comatose condition Seizures 72 hours after start of treatment Continued excessive irritability Focal neurologic findings Persistently abnormal CSF findings Relapse or recurrence pyogenic meningitis investigations
Rapid diagnostic tests Concurrent immuno electro phoresis Latex particle agglutination ELISA to detect bacteria antigen in CSF CSF lactate level Enzyme radioisotope to detect activity of ß lactamase in CSF Gram staining Smears of petechial or purpuric lesions on skin pyogenic meningitis investigations
Management Supportive measures Vitals recorded every 15 – 30 minutes until patient is stable Neurologic examinations and seizure evaluation Measure head circumference in children <18 months Intake and output record pyogenic meningitis
Body weight, serum electrolytes monitored 12 hourly For fever sponge and give antipyretics Feeding continued and give tube feeding if necessary Fluid restricted to 60%, not indicated in hypotension Care of comatose patient IV diazepam for seizures, phenobarbitone for recurrent seizures pyogenic meningitis management supportive
Specific measures Antibiotics Appropriate antibiotic given by culture report Term infants in 1 st month given combo of ampicillin with gentamicin or cefotaxime Low birth weight preterm infants presenting late should be given vancomycin and an aminoglycoside pyogenic meningitis management
1 – 2 month infants given ampicillin ad ceftriaxone Resistant strains treated with vancomycin alternatively meropenem Duration of therapy is 7 – 10 days Steroids Dexamethasone for 2 – 4 days Given before antibiotic is started for good result pyogenic meningitis management specific
Treatment of complications Cerebral edema and raised ICP Head elevated about 30° Steroids for reducing inflammation and brain water content Mannitol Subdural effusion Symptomatic effusion should be aspirated pyogenic meningitis management
Subdural effusion
Inappropriate ADH secretion Hyponatremia , coma, seizures, weight gain, puffiness of face, decreased urine output Treated with fluid restriction and diuretics Waterhouse Friderichsen syndrome Patient in shock with hypotension petechial rash Give normal saline/plasma, steroids and dopamine infusion pyogenic meningitis management treatment of complications
Prognosis Worse prognosis in young children with higher bacterial colony counts, intractable seizures, subdural effusion, bacteremia and prolonged fever, thrombocytopenia, low ESR, absence of leukocytosis , DIC, rapidly progressive purpura in 12hours, hypotension or coma Mortality rate is 8 – 25% 35% have permanent deficit pyogenic meningitis
Prevention Vaccination Vaccines available against S. pneumoniae, N. meningitides and H. influenza type b Pneumococcal polysaccharide vaccine available Meningcoccal vaccine for high risk group and children H. influenza vaccine given for all >2months infants pyogenic meningitis
Antibiotic prophylaxis Meningococcal The dose of rifampicin recommended is 10mg/kg given 12hourly for 2days H. Influenzae Rifampicin 20mg/kg/day for 4 days For all house contacts and patient Streptococcus pneumoniae No prophylaxis pyogenic meningitis