Subinhibitory antibiotic concentrations promote the horizontal transfer of plasmid-borne resistance genes from Klebsiellae pneumoniae to Escherichia coli

Manlin Ding; Zi Ye; Lu Liu; Wei Wang; Qiao Chen; Feiyang Zhang; Ying Wang; Åsa Sjöling; Alberto J Martín-Rodríguez; Renjing Hu; Wenbi Chen; Yingshun Zhou

doi:10.3389/fmicb.2022.1017092

Subinhibitory antibiotic concentrations promote the horizontal transfer of plasmid-borne resistance genes from Klebsiellae pneumoniae to Escherichia coli

Front Microbiol. 2022 Nov 7:13:1017092. doi: 10.3389/fmicb.2022.1017092. eCollection 2022.

Authors

Manlin Ding^{1

2}, Zi Ye¹, Lu Liu¹, Wei Wang¹, Qiao Chen¹, Feiyang Zhang¹, Ying Wang¹, Åsa Sjöling³, Alberto J Martín-Rodríguez³, Renjing Hu⁴, Wenbi Chen¹, Yingshun Zhou¹

Affiliations

¹ Department of Pathogenic Biology, School of Basic Medicine, Southwest Medical University, Luzhou, China.
² Department of Clinical Laboratory, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China.
³ Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
⁴ Department of Laboratory Medicine, The Affiliated Wuxi No. 2 People's Hospital of Nanjing Medical University, Wuxi, China.

Abstract

Horizontal gene transfer plays an important role in the spread of antibiotic resistance, in which plasmid-mediated conjugation transfer is the most important mechanism. While sub-minimal inhibitory concentrations (sub-MIC) of antibiotics could promote conjugation frequency, the mechanism by which sub-MIC levels of antibiotics affect conjugation frequency is not clear. Here, we used Klebsiella pneumoniae SW1780 carrying the multi-drug resistance plasmid pSW1780-KPC as the donor strain, to investigate the effects of sub-MICs of meropenem (MEM), ciprofloxacin (CIP), cefotaxime (CTX), and amikacin (AK) on conjugational transfer of pSW1780-KPC from SW1780 to Escherichia coli J53. Our results showed that the transfer frequencies increased significantly by treating SW1780 strain with sub-MIC levels of MEM, CIP, CTX and AK. Transfer frequencies at sub-MIC conditions in a Galleria mellonella were significantly higher than in vitro. To investigate gene expression and metabolic effects, RT-qPCR and LC-MS-based metabolome sequencing were performed. Transcript levels of T4SS genes virB1, virB2, virB4, virB8, and conjugation-related genes traB, traK, traE, and traL were significantly upregulated by exposure to sub-MICs of MEM, CIP, CTX, and AK. Metabolome sequencing revealed nine differentially regulated metabolites. Our findings are an early warning for a wide assessment of the roles of sub-MIC levels of antibiotics in the spread of antibiotic resistance.

Keywords: T4SS; antibiotic; conjugation frequency; metabolome; plasmid; sub-MIC.