Prevalence of silver resistance determinants and extended-spectrum β-lactamases in bacterial species causing wound infection: First report from Bangladesh

Background: The use of silver is rapidly rising in wound care and silver-containing dressings are widely used along with other antibiotics, particularly β-lactams. Consequently, concerns are being raised regarding the emergence of silver-resistance and cross-resistance to β-lactams. Therefore, this study aimed to determine the phenotypic and genotypic profiles of silver-resistance and extended-spectrum β-lactamases in isolates from chronic wounds. Methods: 317 wound swab specimens were collected from tertiary hospitals of Dhaka city and analysed for the microbial identification. The antibiotic resistance/susceptibility profiles were determined and phenotypes of silver resistant isolates were examined. The presence of silver-resistance (sil) genes (silE, silP, and silS) and extended-spectrum β-lactamases (ESBL) (CTX-M-1, NDM-1, KPC, OXA-48, and VIM-1) were explored in isolated microorganisms. Results: A total of 501 strains were isolated with Staphylococcus aureus (24%) as the predominant organism. In 29% of the samples, polymicrobial infections were observed. A large proportion of Enterobacterales (59%) was resistant to carbapenems and a significantly high multiple antibiotic-resistance indexes (>0.2) were seen for 53% of organisms (P ​