Hemophilus influenzae meningitis - common in children under

leptomeninges caused by infectious agents, however infiltration of the, meninges by leukaemic or other malignant cells also produces inflammatory meningitis For bacterial meningitis, peak age of incidence is less than 5 years Neonates, particularly premature are at particular risk. Mechanism of infection - Pathogens usually gain access to the meninges through the blood stream. Most of the organisms causing bacterial meningitis are commonly carried in the upper respiratory tract, and there is evidence that invasion is triggered or facilitated by a coincident infection with a second pathogen (e g. influenza virus) causing mucosal damage or an immunosuppressive effect. Infectious causes of meningitis Bacterial Naegleria Aseptic meningitis - (a) Viral - e.g. HSV 2, polio. (b) Partially treated pyogenic meningitis (c) Non-infective causes - (1) Vasculitis (esp SLE) (ii) Meningeal carcinomatosis. (iii) Sarcoidosis. (iv) Bechet's/whipple's disease. VogtKoyanagi syndrome. (d) Specific infections in which causative agent may not be identified on ordinary microscopy or culture - TB or cryptococcal meningitis, neurosyphilis, leptospirosis, brucellosis.(e) Parameningeal suppuration. Clinical Features - In meningitis of any etiology the clinical features relate to three causes - 1. Infection - Fever, rigors, toxemia. 2. Increased intracranial pressure - Headache, nausea, vomiting, deterioration of consciousness and convulsions. 3. Meningeal irritation and inflammation - Neck rigidity, positive Kernig's sign, photophobia. ACUTE BACTERIAL MENINGITIS 1. Meningococcal- meningitis Etiology - Age - predominantly in children and young adults, more often during winter epidemics. Transmission - by way of nasopharynx. Carriers are the principal source of transmission. Acquisition is followed by meningitis and septicemia. Incubation period - 1 to 5 days. Clinical features -1. STAGE OF INVASION -Abrupt onset with severe headache, vomiting of cerebral type, fever, pains in neck and back, rigors or in children convulsions, restlessness, insomnia, delirium. 2. MENINGEAL STAGE - (a) More severe headache, intense lumbar pain. (b) Muscular rigidity - Neck rigidity, head retraction. Kernig's and Brudzinskis signs, sometimes muscular twitchings and tremors (c) Ocular symptoms - include optic neuritis, uveitis or purulent choroiditis usually unilateral. Optic atrophy may result particularly in association with hydrocephalus. Conjunctivitis and corneal ulcers. (d) Rash - Erythematous macules which soon become petechial (spotted fever). Petechiae in the conjunctivae. (e) Temperature variable, usually more than 30°C. (f) Exaggeration of deep jerks. (g) Retention of urine and constipation. (h) Herpes febrilis. (i) Pulse -slow in relation to temperature, may be irregular. (j) Rapid emaciation. DIAGNOSIS - (a) Leucocytosis - 20,000-30,000 per c. mm. (b) CSF - Turbid or purulent, under pressure, large number of pus cells mainly polymorphs , and presence of meningococci on smear or culture. (c) Polymerase chain reaction-(PCR)-based identification of bacterial pathogens in cellular CSF increases menigococcal diagnostic rates. Complications and sequelae - 1 Septicemia - Meningitis is associated with meningococcal septicemia and the organism may settle in lungs, bones, joints or eyes causing focal infection. 2. Arthritis - either purulent occurring early in the illness, or arthritis of later onset, possibly due to immune reaction. 3. Neurological - (a) Cerebral oedema of severe degree causing fluctuating neurological signs. (b) Focal neurological damage -e.g. deafness. (c) Psychiatric problems and mental retardation. (d) Hydrocephalus - rare 4 Cardiovascular - Myocarditis. 5. Waterhouse-Friderichsen syndrome - from haemorrhagic necrosis of both adrenals. Circulatory failure, cyanosis and widespread petechiae or purpura. Circulating steroid levels are usually high 6. DIC - often present Treatment - Benzylpenicillin 20-30 mg/kg 4-houhy for 5-7 days. If penicillin allergy. Cephalosporin (e.g. cefotaxime 1-2g i.v. 12 hrly). PROPHYLAXIS - Penicillin does not eradicate the organism from nasopharynx. Patient, and any close contacts should be given rifampicin 10 mg/kg b. d for 2 days. Ciprofloxacin 500 mg in a single dose, if rifampicin is contraindicated Menigococcal vaccine (A and C. and W 135) can be given. 2. Pneumococcal meningitis -associated with lobar pneumonia, rarely with chronic otitis media, sinusitis or head injury. Muscular spasms common More severe toxemia. CSF thick greenish fluid Gram positive diplococci in CSF and blood, or detection of pneumococcal antigen in CSF. Tr. - Penicillin or cefotaxime/ceftriaxone for atleast 7 days and continued till patient is apyrexial for 48 hrs. VACCINATION - Vaccine is effective and should be given to all patients in high-risk groups, other than neonates, in whom it is of limited efficacy. Patients undergoing splenectomy should be immunized before surgery. 3. Hemophilus influenzae meningitis - common in children under 5. Preceding or accompanying infection of respiratory or ear infection. The illness often develops insidiously with drowsiness and irritability. Subdural effusion is a common complication and may cause convulsions or become infected. CSF purulent with a high protein and polymorph count and low sugar. H. influenzae - Can be seen and grown on culture. Tr. - Benzylpenicillin parenterally, or if allergy to penicillin cefotaxime or