Prevalence of hypervirulent Klebsiella pneumoniae and application of the novel Klebsiella phage vB_KpnP_D39 for biocontrol of serotypes K1, K2, and K57 in prepared food-related samples.

In recent years, the contamination of Klebsiella pneumoniae has raised significant concerns about the potential risks to human health. The presence of K. pneumoniae in prepared food-related samples and efficient control is of importance for ensuring food safety. In this study, 300 samples were collected from markets in Hefei, China, and 45 K. pneumoniae isolates were isolated from aquatic products (n = 30), vegetables (n = 9), and ready-to-eat foods (n = 6), respectively. Among these isolates, the capsular serotypes K1, K2, and K57 accounted for the highest percentage, totaling 33.33 % (15/45), and the predominant sequence types were ST23, ST412, and ST11. Additionally, twenty-six isolates (26.9 %) were identified as hypervirulent K. pneumoniae (hvKp), and all were multidrug-resistant (MDR). Notably, the strains carrying iucA generate higher levels of siderophores compared to those that were negative for iucA (P < 0.01). Furthermore, a novel lytic phage vB_KpnP_D39 (D39), which specifically targets multiple hypervirulent capsular serotypes (K1, K2, and K57), was isolated from sewage samples collected from an effluent treatment plant in Hefei, China. D39 maintained highly lytic activity over a pH range of 3.0 to 11.0 and from 20 to 60 °C. Using transmission electron microscopy, a typical podovirus morphotype of D39 was observed. Genomic analysis indicated that D39 belongs to a novel species within genus Przondovirus, and genes associated with virulence and antibiotic resistance were not identified. In practical applications, D39 has been confirmed to significantly destroy biofilm formation and effectively prevent contamination by K. pneumoniae in food production. These findings provide information about the contamination of prepared food-related samples by MDR-hvKp, and a potential biocontrol agent for prevention and control.