Search

A 23-day-old infant presented with apnea and was found to have Citrobacter diversus meningitis and brain abscess. The organism persisted in brain abscess fluid for over 4 weeks despite adequate antibiotic therapy. Cranial computed tomography demonstrated persistent radiolucencies in both frontal lobes, and midline shift, long after completion of antibiotic therapy. Effective therapy of C. diversus meningitis and brain abscess may require use of an antibiotic active within phagocytes, and judicious surgical drainage. A high prevalence of brain abscess mandates cranial computed tomography for any infant with C. diversus meningitis.

The pathogenesis of Citrobacter diversus meningitis and brain abscess was studied in infant rats. Two-day-old rats were inoculated intraperitoneally and intranasally with C. diversus. C. diversus strain 4277, lacking the 32,000-molecular-weight outer membrane protein that appears to be a marker for strains causing meningitis in human neonates, was more likely to produce bacteremia, meningitis, and death in rats than was strain 4036, which possesses this outer membrane protein. Strain 4036 was, however, more likely than strain 4277 to produce ventriculitis and brain abscess. In the infant rat, central nervous system involvement by C. diversus begins with bacteremia and leptomeningitis, followed by ventriculitis and direct extension of infection into periventricular brain parenchyma. Large numbers of bacteria persist inside inflammatory cells, an observation suggesting resistance to intraphagocytic killing. Bacterial strain differences, possibly related to the presence of a 32,000-molecular-weight outer membrane protein, may account for histopathologic differences in the brains of infant rats with C. diversus meningitis.