본 연구는 항생제 내성 Salmonella Typhimurium CCARM 8009을 저해하기 위한 phage와 항생제 조합처리의 효과를 평가하였다. 디스크 확산법과 액체배지 희석법에 의해 phage와 항생제의 상승 저해효과를 측정하였고 배양을 통한 항생제 내성 유도를 평가하였다. Phage를 처리한 cefotaxime, chloramphenicol, ciprofloxacin, erythromycin의 디스크의 저해 구역은 각각 13.6%, 19.3%, 12.7%, 78.8% 로 증가되었다. Phage와 항생제 조합 처리에 의해 tetracycline, chloramphenicol, ciprofloxacin, erythromycin, streptomycin의 최소생육억제농도는 각각 64, 4, 0.0078, 64, 256 mg/mL으로 감소되었다. Phage와 항생제의 조합 처리는 항생제 내성 S. Typhimurium CCARM 8009을 효과적으로 저해하였다 (4 log reduction). 본 결과는 phage와 항생제의 조합처리는 항생제 내성균을 제어하기 위한 방법으로 충분히 응용가치가 높음을 보여주고 있다.

In this study, we investigated the efficacy of Salmonella phage P22 combined with antibiotics to inhibit antibiotic-resistant S. Typhimurium CCARM 8009. The synergistic effect of phage P22 and antibiotics was evaluated by using disk diffusion and broth dilution assays. The development of Antimicrobial resistance was determined after time-kill assay. The antibiotic susceptibility assay showed the inhibition zone sizes around the antibiotic disks were increased up to 78.8% in the presence of phage (cefotaxime; 13.6%, chloramphenicol; 19.3%, ciprofloxacin; 12.7% and erythromycin; 78.8%). The minimum inhibitory concentration values of the combination treatment significantly decreased from 256 to 64 mg/mL for tetracycline, 8 to 4 mg/mL for chloramphenicol, 0.0156 to 0.0078 mg/mL for ciprofloxacin, 128 to 64 mg/mL for erythromycin and 512 to 256 mg/mL for streptomycin. The number of S. Typhimurium CCARM 8009 was approximately 4-log lower than that of the control throughout the combination treatment with phage P22 and ciprofloxacin delete at 37oC for 20 h. The results indicate that the development of antimicrobial resistance in S. Typhimurium could be reduced in the presence of phage treatment. This study provides promising evidence for the phage-antibiotic combination as an effective treatment to control antibiotic-resistant bacteria.

ABSTRACT
Materials and Methods
    Bacterial strains and culture conditions
    Bacteriophage propagation and titer determination
    Disk diffusion assay
    Broth dilution assay
    Time-kill assay
    Antimicrobial resistance development
    Statistical analysis
Results and Discussion
    Antibiotic susceptibility profiles of antibioticresistantS. Typhimurium in the presence of phages
    Synergistic effect of phage and antibiotic on theinhibition of antibiotic-resistant S. Typhimurium
    Development of antimicrobial resistance of S.Typhimurium treated with phage and antibiotic
국문요약
References

• Kantiya Petsong(Department of Food Technology, Prince of Songkla University)
• Kitiya Vongkamjan1, Juhee Ahn(Department of Medical Biomaterials Engineering, Kangwon National University) Correspondence to