Phenotypic and molecular characterization of multidrug-resistant Enterobacteriaceae clinical isolates from intensive care units at Menoufia University hospitals

Objectives The objectives of the study were to determine the prevalence of multidrug-resistant Enterobacteriaceae spp. isolated from different ICUs at Menoufia University hospitals; to detect the presence of extended-spectrum β-lactamases (ESβLs), AmpC β-lactamases, and carbapenemases among the isolated pathogens by using phenotypic methods; and to investigate the presence of blaKPCand blaNDMresistance genes using real-time PCR. Background ESβL producers are associated with increased morbidity and mortality, especially among patients in ICUs. Carbapenemases are diverse enzymes that vary in the ability to hydrolyze carbapenems and other β-lactams. Materials and methods This study involved 270 clinical specimens from 160 patients. ESβL production was detected by resistance to third-generation cephalosporins and aztreonam and confirmed by combined disk test. AmpC production was detected by cefoxitin disk test and confirmed by AmpC disk test. Carbapenemases were detected by resistance to imipenem, meropenem, and ertapenem, and then confirmed by modified Hodge test, phenylboronic acid combined disk (PBA-CD) test, and imipenem/EDTA combined disk (IPM/EDTA-CD) test. Carbapenemase gene (blaKPCand blaNDM) detection was performed by real-time PCR. Results In all, 52.89% of Enterobacteriaceae isolates were extreme drug resistant, 26.45% were pandrug resistant, and 14.88% were multidrug resistant. Carbapenem resistance was 60.33% for imipenem, 65.29% for meropenem, and 85.95% for ertapenem. Risk factors associated with ICUs were ICU stay greater than and equal to 14 days, exposure to invasive procedures, and comorbid conditions. ESβL production occurred in 41.32% and AmpC occurred in 32.23% of Enterobacteriaceae spp. Carbapenemase production was detected in 69.86%; Klebsiella pneumoniae carbapenemase (KPC) was detected in 60.27%; and metallo-β-lactamase was detected in 75.34%. blaKPC gene was detected in 26.03% of imipenem-resistant Enterobacteriaceae spp., whereas blaNDMgene was not detected in all tested isolates. Conclusion Surveys of the prevalence, antibacterial susceptibility patterns, and identification of resistance patterns of bacterial isolates are important for determining appropriate empirical therapy for infections in critically ill patients.