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. 2021 Mar 5:14:917-928.
doi: 10.2147/IDR.S292431. eCollection 2021.

In vitro and in vivo Effect of Antimicrobial Agent Combinations Against Carbapenem-Resistant Klebsiella pneumoniae with Different Resistance Mechanisms in China

Enbo Liu #  1 , Peiyao Jia #  1   2 , Xue Li #  1   3 , Menglan Zhou  1   2 , Timothy Kudinha  4   5 , Chuncai Wu  1 , Yingchun Xu  1 , Qiwen Yang  1
Affiliations

In vitro and in vivo Effect of Antimicrobial Agent Combinations Against Carbapenem-Resistant Klebsiella pneumoniae with Different Resistance Mechanisms in China

Enbo Liu et al. Infect Drug Resist. .

Abstract

Objective: This study aimed to evaluate the in vitro and in vivo effects of different combinations of antimicrobial agents against carbapenemase-producing and non-producing Klebsiella pneumoniae from China.

Methods: A checkerboard assay of meropenem (MEM), amikacin (AK), tigecycline (TGC), colistin (COL) and their combinations was carried out against 58 clinical carbapenem-resistant K. pneumoniae (CRKp) isolates, including 11 carbapenemase-non-producing K. pneumoniae isolates and 21 isolates producing KPC-2 enzyme, 11 NDM-1, 13 IMP, one VIM-1 and one OXA-48. The checkerboard assay was analyzed by the fractional inhibitory concentration index (FICI). A time-kill assay and Galleria mellonella infection model were conducted to evaluate the in vitro and in vivo effects of the four drugs alone and in combination.

Results: In the checkerboard assay, TGC+AK and MEM+AK combinations showed the highest synergistic effect against KPC-2 and NDM-1 carbapenemase-producing isolates, with synergy+partial synergy (defined as FICI <1) rates of 76.2% and 71.4% against KPC-2 producers, and 54.5% and 81.8% against NDM-1 producers. TGC+AK and MEM+COL combinations showed the highest rate of synergistic effect against IMP-producing isolates. Against carbapenemase-non-producing isolates, TGC+COL and TGC+AK combinations showed the highest rate of synergy effect (63.6% and 54.5%). MEM+AK showed a synergistic effect against one VIM-1 producer (FICI=0.31) and an additivite effect (FICI=1) against one OXA-48 producer. In the time-kill assay, COL+AK, COL+TGC, COL+MEM and AK+TGC showed good synergistic effects against the KPC-2-producing isolate D16. COL+MEM and COL+TGC combinations showed good effects against the NDM-1-producing isolate L13 and IMP-4-producing isolate L34. Against the carbapenemase-non-producing isolate Y105, MEM+TGC and COL+AK showed high synergistic effects, with log10CFU/mL decreases of 6.2 and 5.5 compared to the most active single drug. In the G. mellonella survival assay, MEM-based combinations had relatively high survival rates, especially when combined with colistin, against KPC-2 producers (90% survival rate) and with amikacin against metallo-beta-lactamase producers (95-100% survival rate).

Conclusion: Our study suggests that different antimicrobial agent combinations should be considered against CRKp infections with different resistance mechanisms.

Keywords: CRKP; Galleria mellonella infection model; antimicrobial agent combinations; carbapenem-resistant Klebsiella pneumoniae; resistance mechanisms; time–kill curve assay.

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Conflict of interest statement

The authors report no conflicts of interest in this work. The funders had no role in the study design, collection, and analysis of data, interpretation of results, or preparation of the manuscript.

Figures

Figure 1
Figure 1
The difference in MIC values between different types of carbapenemase. (A) Meropenem (MEM); (B) tigecycline (TGC); (C) colistin (COL); (D) amikacin (AK).
Figure 2
Figure 2
In vitro time–kill assay using meropenem (MEM), colistin (COL), tigecycline (TGC) and amikacin (AK), either alone or in combination, against six CRKps with different resistance mechanisms
Figure 3
Figure 3
Survival rate of infected Galleria mellonella larvae treated with different drugs: meropenem (MEM), colistin (COL), tigecycline (TGC) and amikacin (AK), or mock-inoculated with sterile saline (controls).
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