Detection and characterization of multidrug-resistant Salmonella enterica serovar Infantis as an emerging threat in poultry farms of Faisalabad, Pakistan

Aims The aim of this study was the molecular identification of Salmonella enterica serovar Infantis (S. Infantis) isolated from poultry samples and their antimicrobial resistance and virulence profiling. Methods and Results A total of 149 isolates, belonging to genus Salmonella, originally isolated from 340 suspected poultry post mortem specimens reported by us earlier were preliminary identified as Salmonella by biochemical methods and confirmed by polymerase chain reaction targeting genus-specific gene invA. Targeting serovar-specific gene fragment (fljB) resulted in confirmation of 54 isolates as S. Infantis which were further confirmed by sequencing of 16S RNA and fljB genes. Swimming and swarming motilities were detected in 98 center dot 1 and 11 center dot 1% isolates respectively. Phenotypic disc diffusion assay against 23 antimicrobial agents showed the highest resistance against pefloxacin (PEF) (94 center dot 4%), chloramphenicol (83 center dot 3%) and imipenem (77 center dot 7%) while 5 center dot 3% isolates showed extended-spectrum beta-lactamase production. Fifty-nine genes reported for antimicrobial resistance and 12 for conferring virulence were targeted. The most prevalent resistance gene for aminoglycosides was aadA (42 center dot 3%), for quinolone resistance determining region parE (62 center dot 5%), for penicillin's Int1 (62 center dot 9%), for chloramphenicol cat3 (66 center dot 1%) and for beta-lactams bla(TEM)(-1) (44 center dot 4%). Among efflux pump coding genes, armA showed highest (74 center dot 2%) prevalence and for virulence, a high prevalence of SopE (89 center dot 2%) showed the zoonotic potential of the isolates. The activity of efflux pumps was detected through Ethidium Bromide-agar method. Conclusions Poultry could act as reservoirs of multidrug resistance Salmonella. Significance and Impact of the Study We firstly report the prevalence and molecular characterization of virulence/drug resistance in S. Infantis from this region and the results may contribute to designing precisely targeted therapy. This study has also highlighted the possible emergence of S. Infantis with zoonotic potential.