2The study investigated the spectrum of antibiotic resistance and the associated genes for 3 aminoglycoside, macrolide and ESBL class of antibiotics using clinical isolates. A total of 430 4 preserved bacterial strains (Acinetobacter baumannii, n= 20; Pseudomonas aeruginosa, n= 26; 5 Klebsiella pneumoniae, n= 42; E.coli, n= 85; Staphylococcus aureus, n= 84; Salmonella Typhi, 6 n= 82; Enterococcus spp., n= 27; Streptococcus pneumoniae, n= 36 and CNS, n= 28) were 7 examined. The strains were isolated from patients admitted to various tertiary hospitals of Dhaka 8 city between 2015 and 2019 with either acute respiratory infections, wound infections, typhoid 9 fever or diarrhea. The isolates were reconfirmed by appropriate microbiological and biochemical 10 methods. Antimicrobial susceptibility tests were done using Kirby-Bauer disk diffusion approach. 11PCR amplification using resistance gene-specific primers for aminoglycoside, macrolide and 12 ESBL class of antibiotics was done and the amplified products were confirmed by Sanger 13 sequencing. Of the total isolates, 53% came out as MDR with 96.6% of E. coli and 90% of 14 Staphylococcus aureus. There was a year-wise gradual increase of MDR isolates from 2015-2018 15 and by 2019 the increase in MDR isolates became almost 2-fold compared to 2015. Among the 16 five ESBL genes investigated, CTXM-1 came out as the most prevalent (63%) followed by NDM-17 1 (22%) and E. coli isolates were the predominant reservoir of these genes. ErmB (55%) was the 18 most frequently detected macrolide resistance gene, whereas aac(6)-Ib (35.44%) was the most 19 prevalent aminoglycoside resistance gene and these genes were most prevalent in E. coli and P. 20 aeruginosa isolates, respectively. CTXM-1 and ErmB (16.66%) were the most frequent partners 21 of coexistence followed by CTXM-1 and aac(3)-II.22 24 Antimicrobial resistance (AMR) is becoming a very challenging problem worldwide. Solving the 25 AMR problem should be the priority of global efforts. Nosocomial infections have been 26 recognized as the hub for thriving multidrug resistant (MDR) pathogens. It is estimated that around 27 8.7% of the hospitalized patients worldwide develop nosocomial infections which is the leading 28 cause of surgical failure, transplant rejection, treatment failure, increased costs and even deaths 29 [1]. Numerous reports suggest that absolute numbers of infections due to resistant microbes are 30 increasing globally [2-4]. It is conservatively estimated that at least 2 million illnesses and 23,000 31 deaths had been caused by antibiotic resistant organisms per year in the USA [5]. The present trend 32 predicts that infections by resistant bacterial pathogens may cause up to 10 million deaths/year -33 more than any other causes -by 2050 and like the most global issues, the problem is inequitably 34 distributed, with approximately 90% of the predicted deaths are estimated to happen in Asia and 35 Africa [6]. Additionally, treatment of the patients infected with resistant pathogens is associated 36 with...

objectives Characterisation 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 b-lactam classes of antimicrobials in bacteria isolated from hospitalised patients in Bangladesh. methods 430 bacterial isolates from patients with respiratory, intestinal, wound infections and typhoid fever, presenting to clinical care from 2015 to 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. results 53% of isolates were multidrug-resistant (MDR), including 97% of Escherichia coli. There was a year-wise gradual increase in MDR isolates from 2015 to 2018, and there was an almost twofold increase in the number of MDR strains isolated in 2019 (P = 0.00058). Among the 5 extended-spectrum b-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 0 )-Ib (35%) genes were the most frequently detected macrolide and aminoglycoside resistance genes, respectively. conclusion MDR pathogens are highly prevalent in hospital settings of Bangladesh.

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