Background: The emergence and spread of carbapenem-resistant Klebsiella pneumoniae (CRKP) pose a threat to public health. Antimicrobial peptides provide a new treatment option for CRKP infections.
Objectives: We studied antibacterial activities of WAM-1 against CRKP in vitro and in vivo and explored its possible mechanism. We verified safety and factors affecting antibacterial effect. Furthermore, anti-inflammatory effects were investigated.
Methods: We selected eight CRKP and eight carbapenem-susceptible K. pneumoniae to explore the antibacterial activity of WAM-1 by broth microdilution (BMD). The possible mechanism was investigated by alkaline phosphatase leakage and propidium iodide (PI). We evaluated safety of WAM-1 by cytotoxicity and haemolysis and effects of temperature and serum on the antibacterial activity. We investigated in vivo efficacy of WAM-1 by the Galleria mellonella infection model. We investigated the effect of WAM-1 on TNF-α.
Results: BMD showed that WAM-1 had a good antibacterial effect with MICs of 2-4 mg/L and MBCs of 4-8 mg/L. RT-qPCR showed that WAM-1 could inhibit the expression of TNF-α. The cytotoxicity and haemolysis test proved that WAM-1 had certain potential application in vivo. Alkaline phosphatase leakage and PI fluorescence showed that WAM-1 was highly likely to exert an antibacterial effect by destroying bacterial membrane. The G. mellonella infection model suggested that WAM-1 may have a good therapeutic effect in vivo. Temperature had little effect on the activity of WAM-1. Serum, however, reduced WAM-1 activity.
Conclusions: WAM-1 has good antibacterial effect and potential anti-inflammatory effect on infection caused by CRKP.
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