Temperature effect on carbapenemase-encoding plasmid transfer

Abstract

Bacteria that cause human infections can acquire antibiotic resistance, and several factors may play a role. Although temperature is known to affect bacterial growth in vitro and regulate the transfer of genes encoding antibiotic resistance, there is little evidence of changes in antibiotic resistance with ambient temperature. We investigated the distribution of antibiotic resistance at different ambient temperatures and evaluated whether temperature affected the transmission of carbapenemase-producing Enterobacterales (CPE). The study on Klebsiella pneumoniae from eight sentinel hospitals of the Korea Global Antimicrobial Resistance Surveillance System (Kor-GLASS) between 2017 and 2021 was included in the analysis. Conjugation experiments were performed at different temperatures for strains harboring representative carbapenemase genes. The resistance rates to most antibiotics, including carbapenems, varied significantly according to ambient temperature (P < 0.047), except for aminoglycosides. The optimal conjugation temperature for blaKPC-carrying plasmids was 25°C (P = 0.030) and plasmids carrying blaNDM showed the highest conjugation frequency at 30°C (P = 0.007). The blaKPC-IncF showed higher stability at 25°C than at 30°C (P = 0.032) or 37°C (P = 0.047), and the plasmid stability of blaKPC-IncX3 was the lowest at 37°C (P = 0.047). The blaNDM-IncF was very stable at 30°C, and blaNDM-IncX3 was the highest at 30°C and the lowest at 37°C (P = 0.049). In conclusion, we confirmed that carbapenemase gene transmission was optimal at 25–30°C. This suggests that more antibiotic resistance-related genes can be transferred in warmer seasons. Therefore, we suggest that ambient temperature plays an important role in the spread and transfer of CPE.