In Vitro Bactericidal Activity of Trimethoprim-Sulfamethoxazole/Colistin Combination Against Carbapenem-Resistant Klebsiella pneumoniae Clinical Isolates

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has emerged as a formidable health challenge in recent years owing to the shortage of effective antibiotics. Colistin is the last and sometimes the only therapeutic option for CRKP infections. Unfortunately, resistance to colistin monotherapy is likely to develop. CRKP in China reportedly exhibit low rates of resistance to trimethoprim-sulfamethoxazole. The aim of this study was to evaluate the in vitro efficacy of trimethoprim-sulfamethoxazole in combination with colistin against four CRKP clinical isolates. The trimethoprim-sulfamethoxazole/colistin combination rapidly killed all four of the tested isolates after 2 h up to 24 h. Trimethoprim-sulfamethoxazole is one of the few remaining antimicrobials with some activity against CRKP. In particular, combined with colistin, trimethoprim-sulfamethoxazole might be promising for the treatment of CRKP infections.