Lytic Capacity Survey of Commercial Phage Against spp. with Varied Genotypic and Phenotypic Characteristics.

is regularly isolated from food processing environments and is endemic in some facilities. Bacteriophage have potential as biocontrol strategies for . In this study, the lytic capacity of a commercial phage cocktail was evaluated against a library of 475 spp. isolates (426 and 49 other spp.) with varied genotypic and phenotypic characteristics. The lytic capacity of the phages was measured by spot assays where lysis was scored on a scale of 0-3 (0 = no lysis; 1 = slight lysis; 2 = moderate lysis; 3 = confluent lysis). Only 5% of all tested spp. isolates, including were either moderately or highly susceptible (score 2 or 3) to lysis by phage when scores were averaged across temperature and phage concentration; 155 of 5700 treatment (multiplicity of infection [MOI] and temperature) and characteristic (genotype, sanitizer tolerance, and attachment capacity) combinations resulted in confluent lysis (score = 3). Odds ratios for susceptibility to lysis were calculated using multinomial logistic regression. The odds of susceptibility to lysis by phage decreased ( < 0.05) if the isolate was previously found to persist or if the phage-bacteria culture was incubated at 30°C; neither isolate persistence or temperature was significant ( ≥ 0.05) when all factors were considered. In addition, lytic efficacy varied ( < 0.05) among pulse field gel electrophoresis (PFGE) pulsotypes and may be affected by host MOI ( < 0.05). There was no effect ( > 0.05) of attachment capacity or sanitizer tolerance on phage susceptibility. This study underscores the complexity of using phage as a biocontrol for spp. in food processing facilities and highlights that phage susceptibility is most greatly impacted by genotype. Further studies are needed to evaluate these findings within a processing environment.