Bacteriophages are considered as alternative antibacterial agents in the food industry and phage therapy due to the widespread of multidrug-resistant pathogen bacteria. The objective of this study was to isolate lytic bacteriophages target to foodborne pathogen Escherichia coli O157:H7. For screening of bacteriophages, 51 samples were collected from sewage, wastewaters of fish farms, slaughterhouses and food factories, and 18 bacteriophages were isolated. The titer of the purified phages samples were changed among 1.7×10 4-1.02×10 8 PFU/ml. All of the isolated phages had lytic activity against E. coli O157:H7 strains and thus formed clear plaques. Four of 18 phages were found to have inhibitory effects against other E. coli strains including CFAI, ATCC 25922 and DSα in addition to E. coli O157:H7. It was observed that only two phages were infective against Salmonella Kentucky DMC35. The Eco-OH-phages were highly infection ability with EOP values from 0.5 to 0.1 against E. coli O157:H7 strains.

Despite the fact that Pseudomonas aeruginosa is as a prominent opportunist pathogen, it is a recondite microorganism in food safety. Due to its high adaptation capability, rapid reproduction and minimal growth necessities, P. aeruginosa is a common bacterium in the food chain. The resistance of P. aeruginosa to various antibiotics in clinical isolates has been extensively investigated and in-depth characterized. Conversely, information on food-borne isolates of this genus and species is insufficient. Therefore, in this study, 208 P. aeruginosa strains were isolated from 144 food samples collected from different provinces, and 10 isolates (from milk samples) with P. aeruginosa-specific characteristics were identified according to their 16S rRNA region. Antibiotic resistances of the identified isolates were determined against azithromycin (macrolides), erythromycin (macrolides), cephoperazon (cephalosporin), ceftazidime (cephalosporin), meropenem (carbapenem), imipenem (carbapenem), amikacin (aminoglycoside), teminoglycosylcin (teminoglycoside), teminoglycosylcin (pinocycycin) antibiotics. In this study, P. aeruginosa isolates were isolated from milk and the results showed that the prevalence of antibiotic resistance was low. It was found that all of the isolates showed 100% sensitivity to imipenem, piperacilin and vancomycin, 90% sensitivity to cephaperazon and meropenem, and 80% sensitivity to amikacin, ceftazidime and gentamycin. The same isolates were found to be 50% resistant to azithromycin, 90% resistant to tetracycline, and 100% resistant to erythromycin, nalidixic acid, ampicillin and chloramphenicol.