Polymyxin B

Polymyxin B (PMB) is a potent antibiotic that binds to and neutralizes LPS (lipopolysaccharides)^[1].

Polymyxin B againsts all K. pneumoniae strains for positive K. pneumoniae carbapenemase (KPC) genes with MIC of 16 to 128 μg/ml^[2]. In vitro,10 µ/mL Polymyxin B was able to neutralize the effect of endotoxin, as contaminant in S. mansoni recombinant antigens produced in E. coli, in inducing TNF-alpha and IL-10 production^[1]. The MIC₅₀ and MIC₉₀ values of polymyxin B against 217 strains of carbapenem-resistant A. baumannii were 0.5 and 1 mg/l, respectively^[3]. The MIC values for polymyxin B against MRSA (Meticillin-resistant Staphylococcus aureus) was in the range of 8-64 μg/mL, while the MIC values for polymyxin B against MRSP (meticillin-resistant Staphylococcus pseudintermedius) was in the range of 0.25-4 μg/mL^[4].

In vivo, mice were treated with 72 mg/kg obviously increased the level of γH2AX foci (indicative of double stranded breaks)^[5]. In vivo, carvacrol 10 mg/kg plus polymyxin B 2 mg/kg exhibite antimicrobial activity in a mouse model of infection, resulting in increased survival and a significant decrease in bacterial load in the blood^[6].

References:
[1] Cardoso LS, et al. Polymyxin B as inhibitor of LPS contamination of Schistosoma mansoni recombinant proteins in human cytokine analysis. Microb Cell Fact. 2007 Jan 3;6:1.
[2] Elemam A, et al. In vitro evaluation of antibiotic synergy for polymyxin B-resistant carbapenemase-producing Klebsiella pneumoniae. J Clin Microbiol. 2010 Oct;48(10):3558-62.
[3] Thamlikitkul V, et al. In vitro activity of polymyxin B against carbapenem-resistant Acinetobacter baumannii. J Med Assoc Thai. 2014 Dec;97(12):1254-8.
[4] Boyen F, et al. In vitro antimicrobial activity of miconazole and polymyxin B against canine meticillin-resistant Staphylococcus aureus and meticillin-resistant Staphylococcus pseudintermedius isolates. Vet Dermatol. 2012 Aug;23(4):381-5, e70.
[5] Yun B, et al. Polymyxin B causes DNA damage in HK-2 cells and mice. Arch Toxicol. 2018 Jul;92(7):2259-2271.
[6] de Souza GH, et al. Synergistic interaction of polymyxin B with carvacrol: antimicrobial strategy against polymyxin-resistant Klebsiella pneumoniae. Future Microbiol. 2024 Feb 8. 

多粘菌素B（PMB）是一种强效抗生素，可结合并中和LPS（脂多糖）^[1]。

多粘菌素B对所有K. pneumoniae carbapenemase（KPC）基因阳性的菌株均具有抗药性，MIC为16至128μg/ml^[2]。在体外，10 µ/mL多粘菌素B能够中和内毒素诱导TNF-α和IL-10产生的作用^[1]，内毒素是在大肠杆菌中产生的S. mansoni重组抗原中的污染物。多粘菌素B对217株carbapenem-resistant A. baumannii 的MIC₅₀和MIC₉₀值分别为0.5和1 mg/l^[3]。多粘菌素B对MRSA（耐甲氧西林Staphylococcus aureus）的MIC值在8-64 μg/mL范围内，而多粘菌蛋白B对MRSP（耐甲羟西林Staphylococcus pseudintermedius）在0.25-4 μg/mL范围内^[4]。

在体内，用72 mg/kg处理的小鼠明显增加了γH2AX病灶的水平（表明双链断裂）^[5]。在体内，香芹酚10 mg/kg加多粘菌素B 2 mg/kg在小鼠感染模型中表现出抗菌活性，从而提高存活率并显著降低血液中的细菌载量^[6]。