Antimicrobial resistance and molecular characterization of Escherichia coli and Staphylococcus aureus isolated from common fast foods in Gazipur city, Bangladesh

The increased trend in fast food consumption in Bangladesh has raised massive public health concerns about bacterial contamination and its resistance pattern to available antibiotics. This study aims to isolate, identify, and molecular characterization of Escherichia coli and Staphylococcus aureus from fast food samples sold within Gazipur City, Bangladesh, determine their antibiotic resistance profiles and virulence gene detection. A total of 120 samples including fuchka, burgers, sandwiches, and chicken roll were collected from different street vendors and restaurants in Gazipur City. Conventional microbiological methods were employed for the isolation and identification of anticipated isolates, while PCR techniques utilizing nuc and malB genes were implemented for molecular detection. Antibiotic sensitivity patterns were assessed using the Kirby-Bauer disc diffusion method and interpreted in accordance with CLSI guidelines. Out of 120 samples, 26 (21.66%) S. aureus and 22 (18.33%) E. coli were phenotypically detected by cultural and biochemical tests, whereas 12 (46.15%) nuc gene of S. aureus and 10 (45.45%) malB gene of E. coli were genotypically detected. The 6 nuc gene of S. aureus isolates exhibited resistance to cefoxitin, oxacillin, and penicillin (100%), and frequently moderate resistance to clindamycin (50%), whereas 83.33% were sensitive to doxycycline, gentamicin, azithromycin, and levofloxacin, respectively. Similarly, all E. coli isolates showed 100% resistance against erythromycin, ampicillin, and 80% resistance elicited against ceftazidime and tetracycline, respectively. Potentially significant for public health, this study found that fast food offered in restaurants was tainted with harmful S. aureus and E. coli isolates. The detection of MDR bacteria in fast food poses immense public health risks, and there is a dire need to improve food safety practices.