Molecular detection of virulence and resistance genes in Salmonella enterica serovar Typhi and Paratyphi A, B and C isolated from human diarrhea samples and lettuce in Burkina Faso

ObjectivesIn Burkina Faso (BF), dirty water, in particular those of the stoppings and the gutter are used for irrigation of vegetables. The aim of this study is to contribute to the knowledge on the molecular level of Salmonella Typhi and Paratyphi circulating in the hospitals and environment next to hospitals in BF.MethodsSalmonella Typhi and Paratyphi strains isolated from patients between 2009 to 2015 and lettuce samples isolated in 2014 in BF were characterized by simple PCR using specific primers.ResultsOut of 100 Salmonella isolated, 53% were from human and 47% from lettuce samples. Globally, the highest prevalence was observed with invA, misL, pipD, orfL and spvR genes in 97%, 96%; 74%; and 21%. Forty of these isolates carried class 1 integron, 31 from clinical samples and 9 from lettuce samples. Sequencing showed seven different gene cassette arrangements, with aadA1 in 13/15 strains, aadA7 and aac(3)-Id in 2/15 strains. Eight percent (8/100) of Salmonella harbored gyrB and parE genes with 6 from clinical and 2 from lettuce isolates. Sequencing showed no mutation in these genes. Three distinct PFGE types were observed from clinical samples with 90-95% similarity in each case. All Salmonella from lettuce had similar pulsotypes.ConclusionThis study showed the diversity virulence and resistance genes harbored of S. Typhi and Paratyphi from both clinical and lettuce samples in BF. Lettuce is a potential source of transmission of Salmonella causing diarrhea among human in BF.