Prevalence and Characterization of the Antimicrobial Resistance and Virulence Profiles of Staphylococcus aureus in Ready-to-Eat (Meat, Chicken, and Tuna) Pizzas in Mansoura City, Egypt

<b>Introduction:</b><i>Staphylococcus aureus</i> is a high-priority foodborne pathogen contributing to several food poisoning outbreaks. Methicillin- and vancomycin-resistant <i>S. aureus</i> (MRSA and VRSA), pose significant public health concerns due to their potential for serious illness, antibiotic resistance, and transmission within both healthcare and community settings. These bacteria can cause numerous infections, ranging from skin and soft tissue infections to life-threatening conditions like bloodstream infections, pneumonia, and endocarditis. Although several publications are concerned with <i>Staphylococcus aureus</i> contamination in ready-to-eat (RTE) food products, little published data is available about its prevalence in pizza, which is widely distributed and consumed worldwide. <b>Methods:</b> The current study is intended to determine the prevalence, virulence genes, and antimicrobial resistance profiles of <i>S. aureus</i> in three hundred ready-to-eat pizza samples (100 each of meat, chicken, and canned tuna pizzas) collected from different restaurants in Mansoura City, Egypt. The typical colonies on Baird-Parker selective agar supplemented with egg yolk tellurite emulsion were counted and further confirmed based on Gram staining, coagulase testing, catalase testing, carbohydrate fermentation, and thermostable nuclease production. The genomic DNA of the confirmed coagulase-positive isolates was prepared and subjected to PCR analyses for detecting the <i>nuc</i> gene, <i>mec</i>A (methicillin resistance gene), and vancomycin resistance gene (<i>vanA</i>), as well as six selected <i>S. aureus</i> virulence genes: <i>sea</i>, <i>seb</i>, <i>sec</i>, <i>sed</i>, <i>hla</i>, and <i>tsst</i>. The antimicrobial resistance profile of the <i>S. aureus</i> isolates was determined against 16 antimicrobial agents belonging to six classes using the agar disc diffusion method according to the Clinical and Laboratory Standards Institute guidelines (CLSI), except for oxacillin and vancomycin, which were assessed using the MIC test. <b>Results:</b> The results revealed that 56% (56/100), 56% (56/100), and 40% (40/100) of chicken, meat, and canned tuna pizzas were positive for <i>S. aureus</i>, with an overall prevalence of 50.7% (152/300). All 560 isolates (100%) were verified as <i>S. aureus</i> based on molecular confirmation of the <i>nuc</i> gene. Interestingly, 48.6% (272/560) and 8.6% (48/560) of the isolates tested were identified as methicillin- and vancomycin-resistant <i>S. aureus</i> (MRSA and VRSA) through detection of <i>mecA</i> and <i>vanA</i> genes, respectively. Among the <i>S. aureus</i> isolates tested, the <i>hla</i> gene was detected in 87.1% (488/560), while the enterotoxin genes <i>sea</i>, <i>seb</i>, <i>sec</i>, and <i>sed</i> were identified in 50% (280/560), 78.6% (440/560), 9.8% (55/560), and 24.5% (137/560) of isolates, respectively. All recovered isolates (<i>n</i> = 560) were classified as multidrug-resistant and were resistant to penicillin, oxacillin, and ampicillin. Moreover, 77% (431/560), 24% (134/560), 8% (45/560), and 8.6% (48/560) of isolates were resistant to cefotaxime, ciprofloxacin, azithromycin, and vancomycin, respectively. <b>Conclusions:</b> The current study emphasizes that ready-to-eat pizza is highly contaminated with multidrug-resistant <i>S. aureus</i>, highlighting the urgent need for rationalizing antibiotic use in both veterinary and human medicine to prevent the transmission of resistant bacteria through the food chain. Additionally, strict adherence to good hygienic practices throughout all stages of the food chain is essential to minimize overall contamination and enhance food safety.