Evaluating the antimicrobial resistance and frequency of AmpC β-lactamases blaCMY-2 gene in Gram-negative bacteria isolates collected from selected hospitals of Iran: A multicenter retrospective study

Abstract Aims This study evaluates the frequency of AmpC-type β-lactamases blaCMY-2 gene and antibiotic resistance (ABR) profile of the third-generation cephalosporin-resistant Gram-negative bacteria (GNB) isolated from selected hospitals of nine cities in Iran. Methods This is a cross-sectional study that investigates relevant data from January 2015 to the end of December 2018. Conventional biochemical tests were conducted to identify bacterial strains, and ABR was evaluated by the disk diffusion method (DDM). β-lactamase-producing GNB were detected using the double-disk synergy test (DDST), and the existence of AmpC β-lactamase blaCMY-2 gene was screened by PCR method. Results A total of 4083 GNB were isolated from selected hospitals in Iran, out of which 1235 (30.2%) isolates were resistant to third-generation cephalosporins. The predominant GNB isolates were A. baumannii, E. coli, and K. pneumoniae. A large number of E. coli (60.3%) were isolated from female samples, and most GNB were isolated from ICU. The GNB had the highest and lowest frequency in >50 and 5-to-14-year age groups, respectively. In general, 337/1235 (27.2%) of GNB were negative in the DDST, and imipenem was the most effective antimicrobial agents on E. coli strains. A. baumannii and P. aeruginosa were resistant to most of the tested antibiotics, and ciprofloxacin was the most effective antibiotic against Enterobacter spp. isolates. AmpC-type β-lactamase blaCMY-2 gene in A. baumannii (48.3%) and E. coli (47.7%) isolates showed the highest frequency. Conclusions These results suggest the necessity of implementing antimicrobial stewardship programs to improve the appropriate prescription of antibiotics.