Outbreak of neonatal Citrobacter diversus meningitis in a suburban hospital

Between February and June, 1983, four cases of Citrobacter diversus neonatal meningitis were identified at a suburban Baltimore hospital. One of the 4 infants died at age 13 months, 2 (both of whom had brain abscesses) have evidence of developmental delay and 1 appears to be normal after 33 months of follow-up. A review of microbiology records revealed that C. diversus had been present in the hospital nursery prior to identification of the first infant with meningitis, with isolation from infants born 7 months, 4 months and 4 days, respectively, before the first meningitis case. C. diversus was isolated from 21 infants born during the outbreak period and from hand or rectal cultures of 5 nursing personnel. All isolates were biotype E, with two distinct clusters of cases identified on the basis of plasmid profile and serotype. In a case-control study isolation of C. diversus was significantly associated with male sex, low birth weight and care by house pediatricians. The outbreak was controlled by stringent infection control measures and exclusion of personnel carriers. During the 24 months following the outbreak 3431 babies discharged from the nursery were cultured for C. diversus; 3 were colonized with the organism.