Exploring Antibacterial Potential of Secondary Metabolites of Bacillus Species against Gram Negative Bacteria Isolated from Junk Foods in Peshawar, Khyber Pakhtunkhwa, Pakistan

Abstract

The increasing consumption of unhygienic fast food has raised serious health concerns due to its association with bacterial food borne diseases. The present study aimed to determine the antibacterial effect of secondary metabolites of Bacillus species against multi-drug-resistant Gram-negative bacteria isolated from the junk foods in Peshawar. A total of 100 samples were collected from various junk foods such as pizza, burger, and shawarma in district Peshawar. Specifically, 33 samples were from pizzas, 33 from burgers and 34 from shawarmas. Three bacterial species, i.e., E. coli, Salmonella and Shigella were identified. Secondary metabolites were produced using the shake flask fermentation method. After an incubation period of 14 days, secondary metabolite extraction was carried out. According to the CLSI 2020 guidelines, antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method on Muller Hinton agar medium. The most contaminated type of junk food was shawarma (39.9%). E. coli exhibited the highest resistance to tetracycline (89.1%) followed by amoxicillin (59.4%). Cefuroxime sodium (96.1%), followed by tetracycline (92.3%) and azithromycin (65.3%) were resistant to Salmonella. Similarly, cefuroxime sodium (84.2%) followed by ampicillin (84.3%) and streptomycin (63.2%) showed resistance to Shigella. During this study, it was observed that Sulphamethoxazole/Trimethoprim showed the strongest activity against E. coli at (31 mm) while Azithromycin (29 mm) was most effective against Shigella. In conclusion, the present study indicated that the junk foods in district Peshawar had unsatisfactory level of contamination with E. coli, Salmonella and Shigella. These findings highlight the need to improve sanitation practices and personal hygiene to reduce the risk of contamination from junk foods. Key words: Bacillus spp; secondary metabolites; antibiotic resistance; E. coli; Salmonella; Shigella.