Abstract
Background and objectives: Extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae is a serious public health issue globally. In this study, the antibiotic resistance genes, virulence factors, mobile genetic elements, and genetic lineages of circulating ESBL-producing K. pneumoniae strains isolated from pigs and humans in Cameroonian abattoirs were investigated using whole genome sequencing (WGS), in order to ascertain zoonotic transmission (viz. from animals to humans and/or vice-versa) in the food chain.Methods: During March–October 2016, 288 nasal and rectal pooled samples from 432 pigs as well as nasal and hand swabs from 82 humans were collected from Cameroon and South Africa. Seven ESBL-producing K. pneumoniae circulating in Cameroonian pig abattoirs were selected and their genomic DNA sequenced using an Illumina MiSeq platform. Generated reads were de novo assembled using the Qiagen CLC Genomics Workbench and SPAdes. The assembled contigs were annotated using RAST and antibiotic resistance genes, virulence factors, plasmids, and bacteriophages were identified with ResFinder, Virulence Finder, PlasmidFinder, and PHAST, respectively.Results: ESBL-producing K. pneumoniae were detected in pigs (34/158; 21.52%) and exposed workers (8/71; 11.26%) in Cameroon only. The circulating K. pneumoniae strains were dominated principally by the sequence type (ST) 14 and 39. In addition, the “high-risk” ST307 clone and two novel STs assigned ST2958 and ST2959 were detected. Genomic analysis identified various antibiotic resistance genes associated with resistance to β-lactams, aminoglycosides, fluoroquinolones, macrolide, lincosamide and streptogramins, rifampicin, sulfonamides, trimethoprim, phenicols and tetracycline. None of the ESBL-producing K. pneumoniae harbored virulence genes. Intermingled K. pneumoniae populations were observed between pig- and human-source within and across abattoirs in the country.Conclusion: Our study shows that ESBL-producing K. pneumoniae is actively disseminating in pigs and occupationally exposed workers in Cameroonian pig abattoirs and is probably underestimated in the absence of molecular epidemiological studies. It suggests pigs, abattoir workers and food products as potential reservoirs and sources of zoonotic transmission in Cameroon. Our findings underline the existence of a potential unheeded food safety and public health threat associated with these resistant strains and reinforce the crucial importance of implementing appropriate food safety measures and promoting rational antibiotic use.
Highlights
Klebsiella pneumoniae is an important Gram-negative bacillus associated with several clinical infections in humans (Perovic et al, 2014)
This study investigated the antibiotic resistance genes, virulence factors, mobile genetic elements (MGEs) and genetic lineages of circulating ESBL-producing K. pneumoniae strains isolated from pigs and exposed workers in Cameroonian abattoirs using whole genome sequencing (WGS), to ascertain zoonotic transmission of ESBL-producing K. pneumoniae in the food chain
The antimicrobial susceptibility results of the ESBL-producing K. pneumoniae isolates are summarized in Table 2, with the resistance observed being corroborated with WGS analyses
Summary
Klebsiella pneumoniae is an important Gram-negative bacillus associated with several clinical infections in humans (Perovic et al, 2014). Of particular concern is the emergence of extendedspectrum β-lactamase (ESBL) producing K. pneumoniae in hospital settings (Perovic et al, 2014) which has considerably increased during the last decade in response to the selection pressure of extensive antibiotic use This resistant strain is considered a significant public health issue due to the limited therapeutic options and increased morbidity and mortality associated with it (World Health Organization [WHO], 2017). K. pneumoniae commonly produces all three groups of enzymes but the latest public health concern has been the emergence of carbapenemase-producing K. pneumoniae and colistin-resistant K. pneumoniae (Hudson et al, 2014; Perovic et al, 2016) These resistance genes are generally carried on mobile genetic elements (MGEs) facilitating their dissemination within and between bacterial species (Founou et al, 2016). The antibiotic resistance genes, virulence factors, mobile genetic elements, and genetic lineages of circulating ESBL-producing K. pneumoniae strains isolated from pigs and humans in Cameroonian abattoirs were investigated using whole genome sequencing (WGS), in order to ascertain zoonotic transmission (viz. from animals to humans and/or vice-versa) in the food chain
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