Studies on the biochemical and antibiotic patterns of the genus Citrobacter

Today three species are recognized in the genus: C. freundii, C. amalonaticus, and C, diversus. C. freundii is known to occur as three varieties: C. freundii H2S +, IND -, C. freundii H2S +, IND +, and C. freundii H2S -, IND -. The role of Citrobacter in disease has not been investigated thoroughly. The organism is a normal inhabitant of the human intestine, being as common as Escherichia coli in infants. With age, the child\u27s intestine begins to show a greater ratio of E. coli to Citrobacter (Nahhas, personal communication). Citrobacter has been reported as a cause of urinary and respiratory tract infections, especially in children. Hodges et at (1978), however, believe that in most cases, Citrobacter is found in a commensalistic relationship with the organism(s) causing the infection. Most patients from whom Citrobacter was cultured and underlying diseases or factors predisposing them to infection. outbreaks of neonatal meningitis in hospital maternity wards and nurseries have been attributed to contamination of nurses\u27 hands and equipment by C. diversus (Anderson et al, 1981; Enzenauer et al, 1982). Osteomyelitis, neonatal diarrhea, neonatal septicemia, and brain abscesses caused by Citrobacter have also been reported (Barton and Walentik, 1982). In January 1983, I began a study of this group with two objectives in mind: to study the biochemical and antibiogram characteristics of Citrobacter isolates from Stockton, California, and, if possible, to expand and update information on the biology of the genus