Citrobacter koseri isolated in Israel, 1972-83.

Cultures of Citrobacter koseri (syn. C. diversus), an opportunistic pathogen that was isolated in Israel during 1972-83, were studied by sero- and biotyping and for susceptibility to antibacterial agents. Of 1,172 cultures, 96% were isolated from adults, more than half from urinary tract infections. Other frequent sources were superficial wounds and discharges from the respiratory and genital tracts. Seventeen strains originated from blood cultures of patients with sepsis and four from the cerebrospinal fluid of newborns with meningitis. The isolates belonged to 17 O groups, 60 serotypes and 5 biotypes. The most frequent serotypes were 15:a:[2], first identified in Israel, and 1:a:[2]. The most frequent biotypes were c and a. No correlation was found between sero- or biotypes and source of isolation or type of disease. Of 720 cultures tested for sensitivity, all were resistant to ampicillin and carbenicillin, but only 9.3% were resistant to one or more of nine other antibacterial agents tested.