SPONTANEOUS MENINGITIS CAUSED BY GRAM-NEGATIVE BACILLI

Objective. To analyze the causative factors, clinical and microbiologi cal characteristics, and prognosis in spontaneous meningitis caused by Gram-negative rods in adult patients. Methods. Descriptive and retros pective study of all clinical records and microbiological findings in patients diagnosed of meningitis by Gram-negative bacilli, from 1973 t o 1995, at Fundacion Jimenez Diaz. Results. Twenty patients had sponta neous meningitis caused by Gram-negative bacilli (2.1% of all diagnose d meningitis during this period). Fourteen patients were older than 65 years (range: 36-81; p < 0.05). Ninety-five percent of cases had an e xtranosocomial origin (p < 0.001). Ninety percent of patients had some underlying disease (p < 0.001). Twelve patients were immunosuppressed . Seven patients had changes in the urinary tract or repeated UTI infe ctions, The most common clinical symptoms were a decrease in conscious ness level, fever, and neck stiffness. Cerebrospinal fluid (CSF) in 18 patients showed cellular and biochemical changes. The CSF smear revea led the presence of Gram-negative bacilli in 15 patients. E. coli was the microorganism recovered most frequently. Immunosuppression (p < 0. 05), septic shock (p < 0.001) and antimicrobial therapy not including a third generation cephalosporin (p < 0.01) were independently associa ted with mortality. Conclusions. Spontaneous meningitis by Gram-negati ve bacilli is an uncommon infection. It occurs mainly in immunosuppres sed patients older than 65 years or with changes in the urinary tract. It usually has an extranosocomial origin. The investigation of CSF is a highly effective for diagnosis. Therapy with third generation cepha losporins has notably improved its prognosis.