Epidemiological analysis of Salmonella enterica ssp enterica serovars Hadar, Brancaster and Enteritidis from humans and broiler chickens in Senegal using pulsed-field gel electrophoresis and antibiotic susceptibility

Aims: Salmonella Hadar, Salmonella Brancaster and Salmonella Enteritidis are the main Salmonella enterica ssp. enterica serovars isolated from poultry in Senegal. Our objective was to analyse the pulsed-field gel electrophoresis (PFGE) and antibioresistance patterns of strains belonging to these serovars and to assess the significance of broiler-chicken meat as a source of human infection. Methods and Results: A total of 142 Salmonella isolates were analysed: 79 were isolated from Senegalese patients with sporadic diarrhoea (11 S. Hadar, nine S. Brancaster and 59 S. Enteritidis) and 63 from poultry ( 30 S. Hadar, 17 S. Brancaster and 16 S. Enteritidis). The PFGE of XbaI- and SpeI-digested chromosomal DNA gave 20 distinct profiles for S. Hadar, nine for S. Brancaster and 22 for S. Enteritidis. Each serovar was characterized by a major pulsotype which was X3S1 in 42% of S. Hadar, X8S1 in 53(.)8% of S. Brancaster and X1S2 in 43% of S. Enteritidis isolates. Human and poultry isolates of Salmonella had common PFGE patterns. Antibiosensitivity tests showed multiresistance ( more than two drugs) was encountered in 14(.)5% of S. Hadar and in 5% of S. Enteritidis isolates. Resistance to quinolones was considered to be of particular importance and 14(.)5% of S. Hadar isolates were found to be resistant to nalidixic acid. Conlcusions: The sharing of similar PFGE profiles among isolates from humans and poultry provided indirect evidence of Salmonella transmission from contaminated broiler meat. But most of the Salmonella isolates remained drug sensitive. Significance and Impact of the Study: Efforts are needed to eliminate Salmonella from poultry meat intended for human consumption. This study has also highlighted the importance of continuous surveillance to monitor antimicrobial resistance in bacteria associated with animals and humans.