Prevalence of colistin Resistance in MDR Escherichia coli and Klebsiella pneumoniae strains isolated from clinical infections in selected hospitals in Isfahan

Background and Aim : The increasing prevalence of colistin resistance in multidrug-resistant(MDR) gram-negative bacteria which caused nosocomial and serious infections , is now an important clinical problem worldwide.The main objective of this study was to determine the antibiotic resistance pattern especially the rate of colistin resistance isolates.Methods : In this cross-sectional study, ۱۴۱ clinical isolates of E. coli (n=۷۸)and K. pneumoniae (n =۶۳) have been obtained from hospitalized people with severe infections in Isfahan. All isolates were identified using standard microbiology tests. The disk diffusion susceptibility testing and the Minimum Inhibitory Concentration(MIC) of colistin were performed according to the Clinical and Laboratory Standards Institute (CLSI ۲۰۲۰) guidelines. Antibiotic disks used in this study included aztreonam ,amikacin ,ciprofloxacin, levofloxacin ,cefepime , ceftriaxone ,ceftazidime ,cefoxitin ,imipenem ,piperacillin/tozabactam. Results : MDR isolates were found in E. coli (۵۵.۳۱%)and K. pneumoniae (۴۴.۶۸%).The results of antibiogram tests showed that most of the MDR isolates were resistant to ciprofloxacin, cefepime, ceftazidime ; however, the most susceptibility among the isolates were to imipenem ,piperacillin/tozabactam, aztreonam .The colistin resistance among E.coli and K. pneumoniae was ۵% and ۵۲.۵% respectively . Conclusion : In this study, high frequency of colistin-resistant E. coli and K. pneumoniae isolates was seen . Also , the increased rate of MIC pattern of colistin resistant bacteria in our severe infections. As respects to that colistin is the last line of severe infections treatment, increasing resistance to this antibiotic lead to higher mortality and hospital costs. It is necessary more sensitivity in early diagnosis and control of nosocomial infections.

کلیدواژه ها:

MDR ، E. coli ، K. pneumoniae ، Resistance ، colistin .