Prevalence, characterization, and transmissible factors of foodborne pathogens in the Al-Qassim Region, Saudi Arabia.

Foodborne illnesses pose a significant public health threat globally, particularly in Saudi Arabia, where the rapid growth of the food service sector has increased the risk of exposure to multidrug-resistant (MDR) bacteria. Traditional microbiological methods are often time-consuming and may lack precision, highlighting the need for faster and more accurate diagnostic alternatives. In this study, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) was employed for the rapid and precise identification of bacterial contaminants in ready-to-eat (RTE) foods, alongside an assessment of their antibiotic resistance profiles. A total of 80 RTE food samples-including chicken shawarma, shish tawook, chicken burgers, and falafel sandwiches-were collected from restaurants across the Al-Qassim region between September and November 2024. Bacterial identification was performed using standard culturing techniques in combination with MALDI-TOF MS, while antimicrobial susceptibility testing was conducted using the Kirby-Bauer disk diffusion method in accordance with CLSI guidelines. The predominant pathogens identified were Escherichia coli (E. coli) (32.5%), Staphylococcus aureus (S. aureus) (27.5%), and Acinetobacter baumannii (A. baumannii) (18.75%), with the highest contamination observed in chicken shawarma samples. MALDI-TOF MS provided high-confidence species-level identifications, with score ranges between 2.00 and 2.49. E. coli isolates exhibited complete resistance (100%) to ampicillin, amoxicillin-clavulanic acid, cefoxitin, and cephalothin. High resistance rates were also observed for norfloxacin (80.8%) and tetracycline (73.1%). Similar MDR patterns were detected in S. aureus and A. baumannii. Imipenem remained the most effective antibiotic, showing 100% susceptibility among E. coli and S. aureus isolates and 93.3% effectiveness against A. baumannii. These findings underscore the critical need for routine microbial surveillance, implementation of rapid diagnostic tools, and enforcement of stringent food safety regulations to curb the spread of antimicrobial-resistant pathogens through the food supply chain.