Development of a novel phage cocktail and its efficacy in controlling carbapenem-resistant Klebsiella pneumoniae in the food production chain

The isolation rate of Klebsiella pneumoniae (K. pneumoniae), particularly carbapenem-resistant K. pneumoniae (CRKP), is increasing in the food production chain, posing a significant threat to public health. This study identified two broad-spectrum K. pneumoniae phages, LAL003 and vBKpnM-YP11 (YP11), isolated from Daqing, China. Both phages were stable under different conditions, including different pH values, temperatures, ultraviolet light, and ethanol exposure. Phages LAL003 and YP11 lysed 54. 55% and 75. 76% of the isolates, respectively, yielding a combined phage cocktail (LAL003 and YP11) with an overall lytic rate of 87. 88%. This phage cocktail exhibited a complementary host range, including various capsular serotypes and CRKP. Morphological and genomic analyses classified LAL003 and YP11 as members of the Jiaodavirus genus within the Straboviridae family, with genome sizes of 166, 210 and 166, 607 bp, respectively. Notably, no virulence factors, or lysogenic or antibiotic resistance genes, were detected in the genomes, and the phage cocktail at a high titer did not exhibit any toxicity to Galleria mellonella. The results demonstrated that the phage cocktail effectively controls CRKP in pork, milk, and lettuce, and eliminates K. pneumoniae and its biofilms from various substrates, including polypropylene, stainless steel, borosilicate glass, and latex. In conclusion, these findings suggest that, because of the safety and efficacy of phage cocktails, they could control the spread of CRKP from animal-derived foods to humans along the production chain, thereby reducing the risk of cross-contamination of food-contact surfaces in real-world production settings and mitigating potential health threats to consumers. • A novel phage cocktail achieved 87. 88% lysis against 68 Klebsiella pneumoniae strains • This phage cocktail targets 11 distinct capsular serotypes for broad coverage • Genomic and Galleria mellonella larvae experiments confirm the safety of the phage cocktail • It effectively inhibits CRKP in pork, milk, and lettuce within a short time • It removes CRKP and its mature biofilms from four common material surfaces