Development of phage-based assay to differentiate ciprofloxacin resistant and sensitive Salmonella Typhimurium.

This study was designed to evaluate the possibility of using phage-amplification assay for discriminating between antibiotic-sensitive and antibiotic-resistant Salmonella Typhimurium. The characteristics of Salmonella phage PBST32 were determined by adsorption rate, one-step growth curve, and lytic activity. The ability of phage-based method to detect S. Typhimurium ATCC 19585 (STCIP) was determined in single culture and bacterial mixtures of S. Typhimurium ATCC 19585 (STWT), Klebsiella pneumoniae, and Staphylococcus aureus. The adsorption rates of PBST32 were 95% and 93% against STWT and STCIP after 20 min, respectively. The PBST32 showed latent period of 20 min and average burst size of 90 against STWT and STCIP. The STCIP was selectively detected in mixtures of S. aureus, K. pneumoniae, and STWT by phage amplification assay. These results provide useful information for designing phage amplification method that can differentially detect antibiotic-resistant pathogens. © The Korean Society of Food Science and Technology 2021.