1Associate Professor, Department of Medical Microbiology, Nosocomial Infection Research Center, Kermanshah University of Medical Sciences, Kermanshah, Iran
2MSc Student, Department of Microbiology, Imam Reaza Hospital, Kermanshah University of Medical Sciences, Kermanshah, Iran
3MSc Student, Department of Medical Microbiology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
Background & Aims: 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.
Methods: 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 integrinencoded
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.
Results: 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.
Conclusion: 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