Acquisition of Tigecycline Resistance by Carbapenem-Resistant Klebsiella pneumoniae Confers Collateral Hypersensitivity to Aminoglycosides.

Hua-Le Chen,Yue Qu,Jian-Ming Cao,Cui Zhou,Yan Jiang,Tie-Li Zhou,Yao Sun,Mei-Mei Li,Xiao-Xiao Zhang

doi:10.3389/fmicb.2021.674502

Abstract

Tigecycline is a last-resort antibiotic for infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). This study aimed to broaden our understanding of the acquisition of collateral hypersensitivity by CRKP, as an evolutionary trade-off of developing resistance to tigecycline. Experimental induction of tigecycline resistance was conducted with tigecycline-sensitive CRKP clinical isolates. Antimicrobial susceptibility testing, microbial fitness assessment, genotypic analysis and full-genome sequencing were carried out for these clinical isolates and their resistance-induced descendants. We found that tigecycline resistance was successfully induced after exposing CRKP clinical isolates to tigecycline at gradually increased concentrations, at a minor fitness cost of bacterial cells. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) found higher expression of the efflux pump gene acrB (5.3–64.5-fold) and its regulatory gene ramA (7.4–65.8-fold) in resistance-induced strains compared to that in the tigecycline-sensitive clinical isolates. Stable hypersensitivities to aminoglycosides and other antibiotics were noticed in resistance-induced strains, showing significantly lowered MICs (X 4 – >500 times). Full genome sequencing and plasmid analysis suggested the induced collateral hypersensitivity might be multifaceted, with the loss of an antimicrobial resistance (AMR) plasmid being a possible major player. This study rationalized the sequential combination of tigecycline with aminoglycosides for the treatment of CRKP infections.

Highlights

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has emerged as one of the deadliest causes of hospital-acquired infections and poses a serious therapeutic concern (Petrosillo et al, 2013)
Efflux pump regulator encoding genes including acrR, ramR and oqxR were amplified by Polymerase chain reaction (PCR) with specific primers (BialekDavenet et al, 2011; Lin et al, 2016)
Antimicrobial susceptibility tests showed that all carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates were resistant to first-line antibiotics except tigecycline and colistin; one isolate was found to be resistant to tigecycline (K537, MIC 8 mg/L, see Table 1)

Summary

Introduction

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has emerged as one of the deadliest causes of hospital-acquired infections and poses a serious therapeutic concern (Petrosillo et al, 2013). Tigecycline and colistin are the very few options in the antibiotic arsenal for infections caused by carbapenem-resistant Enterobacteriaceae (Stein and Babinchak, 2013; Sun et al, 2013). Resistance to tigecycline of Klebsiella or other Enterobacteriaceae has emerged after its wide use in clinical settings, either as a monotherapy or in combination with other antibiotics (Woodford et al, 2007; Poulakou et al, 2009; Hirsch and Tam, 2010; Sekowska and Gospodarek, 2010; Stein and Babinchak, 2013; Sun et al, 2013; Gonzalez-Padilla et al, 2015). A unique enzymatic inactivation mechanism mediated by Tet(X3) and Tet(X4), has been associated with tigecycline resistance of numerous carbapenems-resistant Enterobacteriaceae (He et al, 2019; Sun et al, 2019)

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