Frequency Of blaCTX-M, blaTEM and blaSHV Genes in Citrobacters Isolated from Imam Reza Hospital in Kermanshah

Background and Citrobacter species can cause opportunistic hospital-acquired infections and their treatment has become problematic following the acquisition of extended spectrum beta- lactamases (ESBLs). The purpose of this study was to determine the frequency of ESBL genes in clinical isolates in Kermanshah Imam Reza Hospital. In this study, 70 Citrobacter isolates were collected from various clinical specimens and confirmed by standard bacteriological tests and API20E Kit. After antibiotic susceptibility testing using disk diffusion method, the presence of ESBL phenotype was determined by combined disk test. Specific primers were used to detect blaCTX-M, blaTEM and blaSHV genes among isolates using PCR. Data was analyzed in SPSS V.18 applying Chi-Square test and Fisher's exact test. From 70 isolates of Citrobacter, 5 (7.1%) were phenotypically positive for ESBL. The PCR test determined 19 isolates (31.6%) genetically positive for ESBL, and the frequency of blaCTX-M, blaTEM and blaSHV genes were 21.3%, 11.4% and 1.4%, respectively. The highest antibiotic resistance of isolates was to cefazolin (84.8%), ampicillin (71.2%) and co-trimoxazole (36.4%), and the lowest was to gentamicin (9.1%), piperacillin/tazobactam (4.5%), and imipenem (1.5%). The results showed that Citrobacter freundiii was the dominant species for hospital-acquired infections in Kermanshah. A high percentage of isolates contained ESBL genes and blaCTX-M was the most common. There was a high gap between the frequencies of genotypic and phenotypic for ESBL, which may indicate ESB genes are not highly expressed in Citrobacter isolates.