Heat Survival of Klebsiella pneumoniae in Infant Formula: The Role of clpC Heat Shock Resistance Genes

Klebsiella pneumoniae is a member of the six highly virulent and antibiotic-resistant bacterial pathogens group (ESKAPE) and poses a significant threat to public health due to its ability to cause both hospital and community-acquired infections. Recent health concerns have emerged about heat-tolerant bacterial contamination in hospital settings, particularly those associated with infant formula preparation. This study aims to evaluate the heat survival of 10 clinical K. pneumoniae strains in infant formula and to investigate the correlation between heat tolerance and the presence of heat shock resistance genes, particularly the clp family of ATPases. Ten strains of K. pneumoniae were exposed to heat at 55 °C for 30 min in infant formula. We assessed their survival rates and determined their D-values. Additionally, we screened for the presence of clpC family genes across representative strains. A wide variation in heat tolerance was observed among the strains. Strain 1701 (ST247, capsular antigen profile O3:K1) exhibited the highest heat tolerance, with a D-value of 12.9 min at 55 °C. The other strains exhibited moderate-to-low heat tolerance. Notably, strain 1701 was the only one that contained the clpC2 gene, suggesting a potential association between the clp gene family and heat resistance. Our results indicate that specific heat shock resistance genes, such as clpC2, may be associated with enhanced heat tolerance observed in K. pneumoniae strains. These findings highlight the potential role of heat shock proteins in bacterial persistence within neonatal healthcare environments.