Meningitis

Bacterial meningitis Lumbar Puncture

1. Clinical presentation. More than 85% of patients with bacterial meningitis classically present with fever, headache, meningismus, and signs of cerebral dysfunction (i.e., confusion, delirium, or a declining level of consciousness ranging from lethargy to coma)

2. Meningismus may be subtle, marked, or accompanied by Kernig's or Brudzinski's signs. It is important to note, however, that these signs are elicited in only 50% or so of adult patients with bacterial meningitis, and their absence does not rule out the diagnosis.

Kernig's sign is elicited with the patient in the supine position. The thigh is flexed on the abdomen, and the knee is flexed as well. The leg then is passively extended and, in the presence of meningeal inflammation, the patient resists leg extension.
Brudzinski's sign - the nape-of-the-neck sign, in which passive flexion of the neck results in flexion of the hips and knees.

3. Cranial nerve palsies (especially involving cranial nerves III, IV, VI, and VII) and focal cerebral signs are seen in 10-20% of cases. Seizures occur in approximately 30% of patients.

With disease progression, patients may develop signs of increased intracranial pressure including coma, hypertension, bradycardia, and palsy of cranial nerve III.

Papilledema is seen in fewer than 1% of cases early in infection, and its presence should suggest an alternative diagnosis.

4. A specific etiologic diagnosis in patients with bacterial meningitis may be suggested by certain symptoms or signs.

a. Characteristic skin rash. For example, nearly 50% of patients with meningococcemia, with or without meningitis, present with a prominent rash located principally on the extremities . The rash is typically erythematous and macular early in the course of illness, but quickly evolves into a petechial phase and then further coalesces into a purpuric form. The rash often matures rapidly, with new petechial lesions appearing during the physical examination. A similar rash may also be seen in patients who have undergone splenectomy with rapidly overwhelming sepsis caused by S. pneumoniae or H. influenzae type b.

b. Rhinorrhea or otorrhea due to a CSF leak may occur in patients who have suffered a basilar skull fracture in which a dural fistula is produced between the subarachnoid space and nasal cavity, the paranasal sinuses, or middle ear. In these patients, meningitis may be recurrent and is most commonly caused by S. pneumoniae.

c. Patients with L. monocytogenes meningitis have an increased tendency to experience seizures and focal deficits early in the course of infection, and some patients may present with ataxia, cranial nerve palsies, or nystagmus due to rhomboencephalitis, although there may be no evidence of parenchymal brain involvement.

5. Some patients may not manifest many of the classic symptoms and signs of bacterial meningitis. For example, elderly patients with bacterial meningitis, especially those with underlying conditions (e.g., diabetes mellitus or cardiopulmonary disease), may present insidiously with lethargy or obtundation, no fever, and variable signs of meningeal inflammation . In patients with head trauma, the symptoms and signs of meningitis may be present as a result of the underlying injury and not meningitis . In all these subgroups of patients, an altered or changed mental status should not be ascribed to other causes until bacterial meningitis has been excluded by CSF examination.

Empiric Antibiotic Treatment:

Cefotaxime 2gms q6-8h
Amp 3gms q4-6h + Cefotaxime 2gms q6-8h
Amp + Ceftazidime 2gms q8h
Vanco 1gm q12h + Ceftazidime 2gms q8h
or
Meropenem 1gm q8h + Vancomycin 1gm q12h

REF
A Practical Approach to Infectious Diseases - Richard E. Reese & Robert F. Betts

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