Resistance profiles, virulence and antimicrobial resistance genes of XDR S. Enteritidis and S. Typhimurium

Avian salmonellosis is concomitant with high financial crises in the poultry industry as well as food-borne illness in man. The present study is designed to investigate the emergence of Salmonella Enteritidis and Salmonella Typhimurium in diseased broilers, resistance profiles, and monitoring virulence and antibiotic resistance genes. Consequently, 450 samples (cloacal swabs, liver, and spleen) were collected from 150 diseased birds from different farms in Giza Governorate, Egypt. Subsequently, the bacteriological examination was done. Afterward, the obtained Salmonella isolates were tested for serogrouping, antibiogram, PCR monitoring of virulence ( inv A, stn, hil A, and pef A), and antimicrobial resistance genes ( bla TEM , bla CTX-M , bla NDM , erm A, sul 1, tet A, and aad A1). The total prevalence of Salmonella in the examined diseased broilers was 9.3%, and the highest prevalence was noticed in cloacal swabs. Among the recovered Salmonella isolates ( n = 35), 20 serovars were recognized as S . Enteritidis and 15 serovars were identified as S . Typhimurium. Almost 60% of the retrieved S. Enteritidis serovars were extensively drug-resistant (XDR) to seven antimicrobial classes and inherited sul 1, bla TEM , tet A , bla CTX-M , ere A, and aad A1 genes. Likewise, 25% of the recovered S. Enteritidis serovars were multidrug-resistant (MDR) to six classes and have sul 1, bla TEM , tet A , bla CTX-M , and ere A resistance genes. Also, 66.7% of the retrieved S. Typhimurium serovars were XDR to seven classes and have sul 1, bla TEM , tet A , bla CTX-M , ere A, and aad A1 genes. Succinctly, this report underlined the reemergence of XDR S . Typhimurium and S. Enteritidis in broiler chickens. Meropenem and norfloxacin exposed a hopeful antimicrobial activity toward the re-emerging XDR S . Typhimurium and S. Enteritidis in broilers. Moreover, the recurrence of these XDR Salmonella strains poses a potential public health threat.