A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Food Engineering and Bioprocess Technology, School of Environment, Resources and Development

Thesis (M. Sc.) - Asian Institute of Technology, 2019

The objective of this study was to analyze antibiotic susceptibility of six of the food pathogens namely Salmonella typhimurium, Staphylococcus aureus, Escherichia coli, Vibrio parahaemolyticus, Bacillus cereus and Listeria monocytogenes. Some of them showed antibiotic resistance in this study. E. coli was resistant to tetracycline antibiotics. Moreover, B. cereus and L. monocytogenes were resistant to one class of antibiotics namely ~-lactam antibiotics (ampicillin, and amoxicillin). Generally, the occurrence of resistance was due to the presence of specific genes which encoding resistant to particular antibiotics. In this study, beta-lactam (blaTEM, and blacuv) genes were detected as antibiotic resistant B. cereus and L. monocytogenes, while blasuv genes of bata-lactam were not found in the antibiotic resistant pathogens. Tetracycline (tetA) genes was detected in antibiotic resistant E. coli, while (tetB) gene were not detected. Furthermore, this study evaluates the antibacterial susceptibility of lactic acid bacteria especially Lactobacillus strains against the three AMR pathogens. The both of Lactobacillus strains exhibited the average inhibition (20-30 mm) on the growth of test pathogens. Moreover, Lactobacillus lac tis was the most effective noticeable strains in inhibiting the growth of Salmonella (31.2 ± 2.4 mm), followed by Lactobacillus casei in inhibiting the growth of L. monocytogenes (25.7 ± 0.6 mm). The occurrence of drug resistance by these common pathogens is a big challenging in food safety and threat to consumer health. In addition, this study has generated and updated new information of pathogenic antibiotic susceptibility and their resistance profiles.