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Food products that are ready-to-eat have become increasingly popular in recent years due to their efficiency, affordability, and convenience. However, there are concerns about public health because certain products, particularly animal products, may contain antibiotic-resistant bacteria. This study aimed to quickly and accurately identify foodborne pathogens, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), in samples of shawarma and chicken burgers using peptide mass fingerprinting (PMF) technology. Additionally, the prevalence and levels of antibiotic resistance in the pathogens were determined. The study utilized 300 samples obtained from fast food restaurants in Al Qassim, Saudi Arabia. A variety of methods were used to identify foodborne pathogens, including culture on specific media, bacterial counts by numerical dilutions of homogenized samples, and proteome identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The Kirby–Bauer method was applied to detect the susceptibility and resistance of the bacteria to various antibiotics. PCR was utilized to identify antimicrobial resistance genes such as blaTEM, tet(A), blaZ, and mecA in S. aureus and E. coli isolates. The percentage of E. coli, S. aureus, Salmonella, Listeria monocytogenes (L. monocytogenes), Acinetobacter baumannii (A. baumannii), and Hafnia alevei (H. alevei) was 34%, 31%, 10.67%, 7.33%, 6.67%, and 4%, respectively. Shawarma samples were found to contain the highest levels of pathogens, compared with chicken burger samples. According to the MBT Compass Flex Series Version 1.3 software, all isolates were identified with 100% accuracy. The log score for MBT identification ranged from 2.00 to 2.56. Among E. coli isolates, ampicillin, and penicillin had the highest resistance rate (100%), followed by tetracycline (35.29%). A number of antibiotics were reported to be resistant to S. aureus, including nalidixic acid (100%), followed by penicillin (96.77%), piperacillin (45.16%), and norfloxacin (32.26%). Some E. coli isolates were susceptible to tetracycline (49.02%), nalidixic acid (47.06%), and piperacillin (43.14%), whereas amikacin was the only drug that was effective against 32.72% of S. aureus isolates. The proportions of the blaTEM and tet(A) genes in E. coli isolates were 55.89% and 45.1%, respectively, whereas S. aureus strains did not possess either of these genes. However, 21.5% and 47.31% of blaz and mecA genes were present among various isolates of S. aureus, respectively. In contrast, E. coli strains did not possess either of these genes. In conclusion, the fast identification and antimicrobial profiles of the foodborne pathogens were useful in identifying which restaurants and fast food outlets may need to improve their food safety practices. Ultimately, our results will be used to devise targeted strategies to control foodborne pathogens.

Staphylococcus aureus (S. aureus) is one of the most prevalent bacterial pathogens recovered from diabetic foot infections (DFIs). Most S. aureus isolates exhibit methicillin resistance, so treatment is recommended with antimicrobials active against methicillin-resistant S. aureus (MRSA) in patients who have risk factors associated with MRSA infections. The main goal of this study was to see if proteomics and molecular methods could be effective in identifying and distinguishing MRSA recovered from DFIs. Since MRSA is highly resistant to β-lactam antibiotics and usually does not respond to other antimicrobial drugs, we evaluated the resistance of MRSA isolates against different antibiotics. The standard procedures were followed for a culture of 250 skin swabs collected from diabetic foot patients. The phenotypic characteristics of 48 suspected S. aureus cultures were determined via microscopic examination, Gram staining, a coagulase test, a BBL™ Staphyloslide™ Latex test, a Staph ID 32 API system, and a Vitek 2 Compact system. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to examine the protein profile of all isolates, and real-time PCR was then used to identify mecA and PVL virulence genes. S aureus isolates were tested using the Vitek 2 Compact for antimicrobial susceptibility using Gram-positive cards (GP71). Among the 48 bacterial isolates tested, 45 (93.75%), 42 (87.5%), and 46 (95.83%) were positive in tube coagulase, the Staph ID 32 API system, and the Vitek 2 Compact system, respectively. We correctly identified all suspected S. aureus isolates (100%) via MALDI-TOF MS with a score value ≥2.00 and differentiated them into 22/48 MRSA (45.83%) and 26/48 MSSA (54.17%) isolates. A higher peak intensity at masses of 5530 Da, 6580 Da, 6710 Da, and 6820 Da was detected in MRSA, but not in MSSA. All MRSA isolates tested positive for the mecA gene, while all isolates tested negative for the PVL gene. The antibiotic susceptibility results showed that 22 (100%), 20 (90.91%), 19 (86.36%), 18 (81.82%), 17 (77.27%), 15 (68.18%), 13 (59.1%), and 12 (54.55%) MRSA strains were resistant to cefoxitin, daptomycin, erythromycin, benzylpenicillin, ciprofloxacin, oxacillin, and clindamycin, respectively. In contrast, all MRSA strains were extremely susceptible (100%) to linezolid, nitrofurantoin, quinupristin–dalfopristin, tigecycline, and vancomycin. Moreover, 20 (90.91%), 18 (81.82%), and 17 (77.27%) of the MRSA strains exhibited high sensitivity against rifampin, trimethoprim–sulfamethoxazole, and gentamicin, respectively. In DFIs, MALDI-TOF MS is a powerful and accurate method of identifying and distinguishing both MRSA and MSSA isolates. A high level of antimicrobial resistance was found in MRSA isolates, and antibiotic therapy based on antibiotic susceptibility patterns is essential for a successful outcome.