Gram-negative bacillary meningitis.

All cases of unusual types of gram-negative bacillary meningitis in a university hospital over a five year period were retrospectively analyzed. These patients comprised 4.2 per cent of cases of bacterial meningitis among all patients, 69 per cent of neurosurgical cases and 42 per cent of neonatal cases. The over-all mortality was 40.3 per cent. The two most common bacterial isolates were Escherichia coli in patients younger than one year and Klebsiella species in patients above that age. Infection may be acquired at birth or at the time of surgery, or may be secondary to spread of infection from other body sites. Gram-negative bacillary meningitis is a nosocomial infection and this diagnosis should be suspected in patients in whom central nervous system infection develops in the hospital.