Characterization of resistance phenotype and genotype is crucial to understanding the burden and transmission of antimicrobial-resistance (AMR). This study aims to determine the spectrum of AMR and associated genes encoding aminoglycoside, macrolide and β-lactam classes of antimicrobials in bacteria isolated from hospitalized patients in Bangladesh.
430 bacterial isolates from patients with respiratory, intestinal, wound infections, and typhoid fever, presenting to clinical care from 2015-2019, were examined. They included Escherichia coli (n= 85); Staphylococcus aureus (n= 84); Salmonella typhi (n= 82); Klebsiella pneumoniae (n= 42); Streptococcus pneumoniae (n= 36); coagulase-negative staphylococci (n= 28); Enterococcus faecalis (n= 27); Pseudomonas aeruginosa (n= 26) and Acinetobacter baumannii (n= 20). Reconfirmation of these clinical isolates and antimicrobial susceptibility tests was performed. PCR amplification using resistance gene-specific primers was done and the amplified products were confirmed by Sanger sequencing.
53% of isolates were multidrug-resistant (MDR), including 97% of Escherichia coli. There was a year-wise gradual increase of MDR isolates from 2015-2018 and there was an almost 2-fold increase in the number of MDR strains isolated in 2019 (P= 0.00058). Among the 5 extended spectrum β-lactamases investigated, CTX-M-1 was the most prevalent (63%) followed by NDM-1 (22%); Escherichia coli was the major reservoir of these genes. The ermB (55%) and aac(6′)-Ib (35%) genes were the most frequently detected macrolide and aminoglycoside resistance genes, respectively.
MDR pathogens are highly prevalent in hospital settings of Bangladesh.

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