Serotyping, drug resistance, virulence, and antibiotic resistance genes of Salmonella isolated from contaminated food

INTRODUCTION: Antibiotic resistance (AMR) is a serious problem for veterinary and human health. Its progression is leading to therapeutic failures and risks taking humanity back to the era before the discovery of antimicrobials. The impact of AMR on the economy is considerable. This study was carried out to assess the extent of AMR in Salmonella isolated from food products. METHODOLOGY: The European Committee on Antimicrobial Susceptibility Testing (EUCAST) standard method and the recommendations of the Antibiotic Susceptibility Committee of the French Society of Microbiology (CA-SFM) version 2023 V.1.0. 19 were used to test antibiotic susceptibility. A total of 41 antimicrobials were tested on the isolates. Virulence genes fimA and stn, and the antibiotic resistance gene CMY-2 were tested by real-time polymerase chain reaction (PCR) on bacterial DNA extracted using the MacheryNagel RNA viral nucleospin extraction kit. The integrated search engine on the National Center for Biotechnology Information (NCBI) website was used to search for the primer sequence of interest for the predefined genes. RESULTS: All the isolates were resistant to at least one antibiotic, while 90% of isolates were multiresistant (resistant to at least 3 antimicrobial agents). All strains tested positive for the presence of the stn and fimA virulence genes, with the exception of one isolate. Similarly, with the exception of one strain, all strains tested positive for CMY-2. CONCLUSIONS: These results point to the progression of AMR, which is increasingly gaining ground, and to the danger of Salmonella virulence as a major agent of food-borne illness in Morocco.