Multi-Drug Resistant (MDR) and carbapenemase co-producing Gram-negative bacilli in northwest of Iran

Abstract

Carbapenemase enzymes confer clinically significant resistance to Gram-negative bacteria, only a few antibiotics with adverse side effects and/or unfavorable in vivo efficacy remains. This study sought to determine the prevalence of carbapenemase producing gram-negative organisms and also investigate the antibacterial susceptibility profile of carbapenem-resistant isolates. In this study, over a two-year period (2017–2019) a total of 140 imipenem and/or meropenem resistant gram negative bacilli were collected from various specimens sent to microbiology laboratory of university hospital. Disk diffusion antimicrobial susceptibility test was used to evaluate MDR isolates; also multiplex polymerase chain reaction and sequencing were performed for confirmation of carbapenemase production. In disk diffusion method, all isolates were resistant to cefazolin. High rate of resistance was observed against imipenem (98.6%), followed by cefotaxime (97.1%), trimethoprim-sulfamethoxazole (91.4%). Colistin was found as the most effective agent with only 5.7% of resistance, followed by amikacin. Based on PCR results and subsequent sequencing, 46.4% of the isolates were genetically recognized to be carrying at least one carbapenemase gene. Encoded carbapenemases were OXA-48-like (18.6%), VIM-2 (15%), IMP-1 (9.3%), KPC (5.7%), NDM-1 (3.6%), and AIM-1 (2.1%). All isolates were negative for SIM, BIC, SPM, GIM and DIM enzymes. Five isolates were co-harbored blaVIM-2 and blaOXA-48. Moreover, co-harbored carbapenemase genes were observed in six isolates as 6 two-genes-harbored profiles. Our results indicate a relatively high incidence of carbapenemase genes. In addition, the emergence of isolates harboring multiple carbapenemases is of great concern, since these isolates will result in a broad-spectrum antibiotic resistance. Molecular characterization of carbapenemase producers can be helpful tool to offer an effective treatment policy. The worrisome high rate of antibiotic resistance highlights the necessity of active surveillance to antibiotic prescription and\\or self-medication by patients.