Molecular Characterization of ESBLs and QnrS Producers From Selected Enterobacteriaceae Strains Isolated From Commercial Poultry Production Systems in Kiambu County, Kenya.

Background: The emergence and spread of Extended-spectrum β-lactamases (ESBLs) in Enterobacteriaceae through the plasmid-mediated exchange have become a major threat to public health by complicating the treatment of severe infections in both animals and humans. Therefore, the current study focused on evaluating the manifestation of ESBLs production from the fecal isolates of E. coli , Shigella spp , Salmonella spp , and Klebsiella spps in commercial poultry production systems of Kiambu County, Kenya.
Materials and Methods: Out of 591 isolates identified as E. coli , Shigella spp , Salmonella spp , and Klebsiella spps from 437 fecal samples, only 78 were phenotypically suggestive to be ESBL producers. The possible ESBL producers were screened for the presence of ^bla TEM, ^bla CTX-M, ^bla OXA, and ^bla SHV using the PCR technique. These isolates were also screened for carriage of the QnrS gene that confers resistance to the fluoroquinolone class of drugs.
Results: The most detected ESBL gene from the isolates was ^bla OXA (n = 20; 26%), followed by ^bla TEM (n = 16, 21%), with the majority of them detected in E. coli . The ^bla CTX-M was identified in all the 4 enteric's bacteria-type isolates tested. Three E. coli and Salmonella spp respectively were found to harbor all the 5 antimicrobial resistance (AMR) gene types. The ^bla TEM, ^bla OXA, ^bla SHV, and QnrS genes were not detected from Klebsiella and Shigella spps . Additionally, most of the AMR gene co-carriage was detected in both E. coli and Salmonella spps as follows ^bla TEM +  ^bla OXA (n = 4); ^bla TEM + QnrS (n = 3); ^bla TEM +  ^bla OXA + QnrS (n = 3), concurrently.
Conclusion: Our findings highlight the significance of commercial poultry production in disseminating transferable antibiotic resistance genes that act as potential sources of extensive drug resistance in livestock, humans, and the environment, leaving limited therapeutic options in infection management.
Competing Interests: Declaration of conflicting interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
(© The Author(s) 2022.)