Background and purpose: Multiple drug resistance in Enterobacteriaceae has restricted the available options for treatment of infections caused by these bacteria. The aim of this study was to investigate the pattern of multidrug resistance and cross-resistance in Enterobacteriaceae causing nosocomial infections in intensive care units during 2014-2015 in eighteen governmental hospitals in Mazandaran province, Iran.

Materials and methods: A cross-sectional descriptive study was performed in which antibiotic susceptibility test to routinely antibiotics was determined by MIC method and "broth micro-dilution” was done according to CLSI.

Results: A total of 35 strains including Klebsiella pneumoniae (24), Escherichia coli (6), and Enterobacter spp (5) were extended-spectrum β-lactamases producer. The prevalence of multidrug resistance in Klebsiella pneumoniae, Escherichia coli and Enterobacter spp were 95.83%, 66.6%, and 80%, respectively. Among the isolates 28.57% exhebited cross-resistance to aminoglycoside antibiotics and 40% were found with cross-resistance to third- and fourth-generation cephalosporins.

Conclusion: Regarding the high prevalence of multidrug resistance and the emergence of cross-resistance to different categories of antibiotics among Enterobacteriaceae causing nosocomial infection, more effective measures should be taken including implementation of infection control programs, isolation of patients infected by multidrug resistance bacteria, and antibiotic stewardship in hospitals.