The Frequency of Carbapenemase Genes in Citrobacter Frundii and Citrobacter Koseri Isolated from Clinical Specimens in Imam Reza Hospital, Kermanshah, Iran

The inappropriate use of antibiotics has led to antibiotic resistance in microorganisms of Enterobacteriaceae family, especially in carbapenems. The aim of this study was to identify the carbapenemase producing Citrobacter frundii and Citrobacter koseri isolated from clinical specimens. One hundred Citrobacter isolates from various patient samples in Imam Reza Hospital, Kermanshah, Iran, were identified using the microbiologic differential tests and API-E20 Kit. After antibiotic susceptibility testing with disc, the isolates resisted to carbapenems were screened using MHT (Modified Hodge Test) for the presence of carbapenemases. Then, carbapenemase genes coded Verona integrin-encoded metallo-beta-lactamase (VIM), Klebsiella pneumoniae carbapenemase (KPC), Imipenemase (IMP), New Delhi metallo-beta-lactamase-1 (NDM) were tested using specific primers via polymerase chain reaction (PCR) method. From 100 isolates, 11 cases were carbapenem resistant. In the phenotypic screening test, 2 isolates were positive. PCR on isolates resistant to carbapenams confirmed VIM gene in 5 isolates: 3 (3.9%) of Citrobacter frundii and 2 (15.4%) of Citrobacter koseri. But the genes of blaKPC, blaVIM, blaIMP and blaNDM were not found in isolates. The highest and lowest antibiotic susceptibility were for meropenem (93%) and cefazolin (1%), respectively. It seems that the prevalence of carbapenemase genes in Citrobacter kosari and Citrobacter frundii was low in Kermanshah; however, VIM gene in these two species is probably more prevalent. This may suggest that most genes have not been high prevalent in this area yet. But, there may be other genes for resistance to carbapenems in our area which need further investigations. The results indicate that carbapenems are still effective antibiotics against Citrobacter species.