Clinical significance of citrobacter isolates

Little is know about the clinical significance of isolating Citrobacter in the clinical laboratory. During a one-year period, 116 Citrobacter isolates were obtained from 77 patients with 83 suspected infectious episodes. The majority of the suspected infectious episodes involved the urinary tract (45%) or respiratory tract (41%). Citrobacter diversus was associated with 42% of the episodes, Citrobacter freundii with 29%, and Citrobacter species with 29%. In 42% of the suspected infectious episodes, the presence of Citrobacter was considered clinically significant; in the others, the significance of the Citrobacter isolates was indeterminate or considered to be commensal. Two thirds of the significant infections were hospital-acquired. Most patients (73%) from whom Citrobacter was cultured had underlying diseases or factors predisposing to infection. These data suggest that Citrobacter is a cause of significant opportunistic nosocomial infection in the hospital.