Molecular Characterization and the Antimicrobial Resistance Profile of Salmonella spp. Isolated from Ready-to-Eat Foods in Ouagadougou, Burkina Faso

Abstract

The emergence of antimicrobial-resistantfood-borne bacteria is a great challenge to public health. This study was conducted to characterize and determine the resistance profile of Salmonella strains isolated from foods including sesames, ready-to-eat (RTE) salads, mango juices, and lettuce in Burkina Faso. One hundred and forty-eight biochemically identified Salmonella isolates were characterized by molecular amplification of Salmonella marker <i>invA</i> and <i>spiC</i>, <i>misL</i>, <i>orfL</i>, and <i>pipD</i> virulence genes. After that, all confirmed strains were examined for susceptibility to sixteen antimicrobials, and PCR amplifications were used to identify the following resistance genes: <i>bla</i> _TEM, <i>temA</i>, <i>temB</i>, <i>StrA</i>, <i>aadA</i>, <i>sul1</i>, <i>sul2</i>, <i>tet(A)</i>, and <i>tet(B)</i>. One hundred and eight isolates were genetically confirmed as <i>Salmonella</i> spp. Virulence genes were observed in 57.4%, 55.6%, 49.1%, and 38% isolates for <i>pipD</i>, <i>SpiC</i>, <i>misL</i>, and <i>orfL</i>, respectively. Isolates have shown moderate resistance to gentamycin (26.8%), ampicillin (22.2%), cefoxitin (19.4%), and nalidixic acid (18.5%). All isolates were sensitive to six antibiotics, including cefotaxime, ceftazidime, aztreonam, imipenem, meropenem, and ciprofloxacin. Among the 66 isolates resistant to at least one antibiotic, 11 (16.7%) were multidrug resistant. The Multiple Antimicrobial Resistance (MAR) index of Salmonella serovars ranged from 0.06 to 0.53. PCR detected 7 resistance genes (<i>tet(A)</i>, <i>tet(B)</i>, <i>bla</i> _TEM, <i>temB</i>, <i>sul1</i>, <i>sul2</i>, and <i>aadA</i>) in drug-resistant isolates. These findings raise serious concerns because ready-to-eat food in Burkina Faso could serve as a reservoir for spreading antimicrobial resistance genes worldwide.