Abstract: ObjectiveTo investigate the drug resistance, the virulence genes and the pulse field gel electrophoresis (PFGE) patterns of 37 strains of Citrobacter isolated from diarrhea patients and food. MethodsThe Kirby-Bauer disk diffusion test was conducted for Citrobacter isolates to test their resistance to 15 antibiotics; the detection of virulence genes (stx1, stx2, hly and eaeA ) of these isolates was performed by routine PCR assay. Homology analysis was performed by PFGE. ResultsAmong 37 strains of Citrobacter, 25 strains were C. youngae, 11 strains were C. freundii and 1 strain was C. braakii. These Citrobacter isolates were sensitive to most antibiotics, but resistant to cephalothin (100%). The results of virulence genes detection were negative for all the isolates. PFGE analysis revealed that the 37 strains belonged to 29 different patterns. The patterns of 6 strains of C. youngae (5 from food, 1 from patient) were same (MAS007), which had epidemiological link. ConclusionThe predominating strains of Citrobacter was C. youngae in the area surveyed. Some of the Citrobacter isolates were multi-drug resistant. PFGE is effective for the subtyping of ICitrobacter/I strains, which is favorable for the tracing of epidemic source. Diarrhea patients might have food borne infection of ICitrobacter/I, and more attention should be paid to it.