Detection and phenotypic characterization of carbapenem non susceptible gram-negative bacilli isolated from clinical specimens

Abstract

Background Multi-drug resistant, extremely drug-resistant, pan-drug resistant, carbapenem-resistant, and carbapenemase-producing gram-negative bacteria are becoming more common in health care settings and are posing a growing threat to public health. Objective The study was aimed to detect and phenotypically characterize carbapenem non susceptible gram-negative bacilli at Ethiopian Public Health Institute. Materials and methods Prospective cross-sectional study was conducted from June 30, 2019, to May 30, 2020, at the national reference laboratory of the Ethiopian Public Health Institute. Clinical samples were collected, inoculated, and incubated in accordance to standard protocol for each sample. Antimicrobial susceptibility testing was done using Kirby Bauer disk diffusion. Identification was done using the traditional biochemical method. Multidrug-resistant and extensively drug-resistant were classified using a standardized definition established by European Centers for Disease prevention and control and the United States Centers for Disease prevention and control experts. Carbapenemase production was confirmed by modified carbapenem inactivation and a simplified carbapenem inactivation method. Meropenem with EDTA was used to differentiate serine carbapenemase and Metallo β-lactamase. Results A total of 1337 clinical specimens were analyzed, of which 429-gram negative bacilli isolates were recovered. Out of 429 isolates 319, 74, and 36 were Enterobacterales, Acinetobacter species, and P. aeruginosa respectively. In our study, the prevalence of Multidrug-resistant, extensively drug-resistant, Carbapenemase-producing, and carbapenem non-susceptible Gram-negative bacilli were, 45.2%, 7.7%, 5.4%, and 15.4% respectively. Out of 66 isolates screened for Carbapenemase, 34.8% (23/66) were Carbapenemase enzyme producers. Ten out of twenty-three Carbapenemase-positive organisms were Metallo-beta-lactamase producers. Thirteen out of twenty-three isolates were serine carbapenemase producers. Three out of 13 serine Carbapenemase positive organisms were Klebsiella pneumoniae Carbapenemase. Conclusion The finding from this study revealed a high prevalence of Multidrug-resistant, extremely drug-resistant, carbapenemase-producing gram-negative bacteria, particularly among Intensive care unit patients at the health facility level, this necessitates a robust laboratory-based antimicrobial resistance monitoring and infection prevention and control program.