The onset of symptoms in acute bacterial meningitis is abrupt. Initially, there is headache, vomiting and fever. Pain and stiffness then start developing in the neck and the back.

In severe cases, there is altered level of consciousness and the patient may have confusion, delirium, lethargy and coma. If the meningitis is uncomplicated, these neurological signs do not develop and there is not much deterioration of consciousness. Presence of neurological signs indicates complications such as cerebral edema and hydrocephalus.

The classic signs of meningitis upon physical examination include neck stiffness, Kernig’s sign and Brudzinski’s sign. Inflammation of the meninges causes reflex spasm of the paravertebral muscles which causes the neck stiffness seen in meningitis. In Kernig’s sign, the patient’s hip is flexed to ninety degrees and then the knee is extended. If the patient feels pain due to spasm of the hamstring muscles, meningitis is indicated. In Brudzinski’s sign, there is spontaneous flexion of the knee and hip when neck flexion is attempted.

Kernig’s and Brudzinski’s signs are positive in around 50% of the patients of meningitis [4] [5]. 50% of the patients with meningococcal meningitis may also have purpuric or petechial rashes principally on the extremities.

In the elderly, the classic signs of meningitis often do not appear and there is an insidious onset with lethargy, variable symptoms and no fever. In neonates, neck rigidity and/or fever are absent as well and the presenting features include irritability, restlessness and refusal to feed.

The following investigations are helpful in establishing the diagnosis of meningitis.

• Cerebrospinal fluid (CSF) examination: The cerebrospinal fluid is examined after lumbar puncture. In bacterial meningitis, there is an increased white cell count with more than 1000 cells per cubic millimeter of the fluid. Polymorph leukocytes are predominant. The protein concentration is also elevated above the normal concentration of 45 mg/dl. The concentration of glucose is low (less than 40 mg/dl in normal patients). In 60 to 90% of the cases, the etiological agent can be identified after gram stain. Cerebrospinal culture also reveals the etiological agent.
• Blood tests: Neutrophilic leukocytosis is seen in the blood. Blood culture for the etiological agent may be positive even when the cerebrospinal fluid culture is negative.
• Coagulation tests: Tests for coagulation such as prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrin degradation product (FDP) should be performed to rule out disseminated intravascular coagulation.
• Renal tests: The urea, creatinine and electrolytes in the serum should be evaluated in order to check renal function. Hyponatremia, if present, indicates syndrome of inappropriate antidiuretic hormone secretion.

Supportive therapy

The supportive treatment of bacterial meningitis includes bed rest and ensuring airway patency. Intravenous fluids are given if there is danger of developing dehydration. If seizures develop, fluid intake is restricted.

Anti-microbial therapy

Bacterial meningitis is treated initially with empirical intravenous antibiotic therapy [6]. Once the cerebrospinal fluid or blood culture results are available, specific antibiotic therapy is initiated [7] [8]. Usually, benzyl penicillin is given for meningococcal meningitis and ceftriaxone is used as an alternative in the patients who can not tolerate penicillin. In the patients suffering from pneumococcal meningitis, ceftriaxone is given. Vancomycin or rifampin may be added if the pathogen is resistant to beta lactam. Hemophilus meningitis is also treated by ceftriaxone. Chloramphenicol may be used as an alternative. Listeria meningitis is treated by ampicillin or gentamycin and cotrimoxazole may be used as an alternative.

Adjunctive therapy

Adjunctive therapy of meningitis consists of the following drugs.

• Mannitol: Mannitol is given in the patients with raised intracranial pressure.
• Glucocorticoids: Glucocorticoids are effective in reducing the incidence of hearing loss and neurological deficits in children [9] [10].
• Anti-epileptics: If the patient develops seizures, diazepam or phenytoin may be given.

The mortality rate in the patients suffering from bacterial meningitis is 19 to 37% [3]. Mortality increases when the disease is not diagnosed or treated early.

Several complications may develop in the patients suffering from bacterial meningitis. These include septicemia, disseminated intravascular coagulation, shock, septic arthritis, syndrome of inappropriate antidiuretic hormone secretion (SIADH) and neurological disturbances.

The common causal agents of bacterial meningitis are the following [1].

• Neisseria meningitides: This pathogen is also called meningococcus and spreads by air borne route. The organism invades through the nasopharynx and causes septicemia usually associated with meningitis.
• Streptococcus pneumonia: Streptococcus pneumonia is often called pneumococcus. Pneumococcal meningitis may be associated with otitis media, pneumonia and malfunction of the spleen [2].
• Hemophilus influenza: Hemophilus influenza infection may be associated with otitis media, sinusitis, epiglottitis and immunodeficiency.
• Listeria monocytogenes: This pathogen causes meningitis in the immunosuppressed, diabetics, alcoholics, pregnant women, neonates and the elderly.

In the developed countries, the incidence of bacterial meningitis is 3 to 5 in 100,000 people. The incidence is higher in undeveloped countries.

Bacterial infection causes an acute inflammatory response of the pia mater and arachnoid mater which become congested and infiltrated with inflammatory cells. A thin layer of pus forms which may later organize to form adhesions which may cause obstruction in the free flow of the cerebrospinal fluid. Cranial nerve damage may also occur at the base of the brain.

Family members and close contacts of the patients of meningococcal meningitis should receive prophylactic antibiotic therapy for two days. For this purpose, ciprofloxacin or rifampin may be used in suitable doses.
Vaccination is also available for prevention of disease caused by group A and C meningococci. Vaccination against group B meningococci is not available.

Bacterial meningitis is the inflammation of the meninges commonly caused by bacteria such as Neisseria meningitides, Streptococcus pneumonia, Hemophilus influenza and Listeria monocytogenes. It is an acute medical condition and may prove fatal if not diagnosed and treated early. The typical features include fever, headache and vomiting followed by neck stiffness and neurological disturbances. The mainstay of treatment is antibiotic therapy along with supportive care.

Bacterial meningitis is the swelling of the membranous sheet that covers the brain in response to infection with bacteria. The patients experience fever, vomiting, headache, stiffness of the neck and diminishing of consciousness. Bacterial meningitis is fatal unless diagnosed and treated early with antibiotics.

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