https://orcid.org/0000-0003-1241-6153
![Sample our Medicine, Dentistry, Nursing & Allied Health journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/5944/TOC-Subject-Sample-2021-Medicine-Dentistry-Nursing-Allied-Health.jpg"})
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.
Ethics Approval and Consent to Participate
The protocol has been reviewed by the human research ethics committee of the Institutional Review Board (IRB) of the Peking Union Medical College Hospital (Ethics Approval Number: S-K1167), and since all bacterial strains were from residual samples used in clinical diagnosis, it was determined that they met the criteria for exemption. This project did not involve any patient information, nor did it affect the normal diagnosis and treatment of patients. After consultation with the IRB, formal ethical approval was reviewed and waived, and written patient consent was not required.
Author Contributions
All authors made substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; took part in drafting the article or revising it critically for important intellectual content; agreed to submit to the current journal; gave final approval of the version to be published; and agree to be accountable for all aspects of the work.
Disclosure
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.