香芹酚联合头孢曲松对耐药性沙门氏菌的体外抗菌作

In vitro antimicrobial effects of carvacrol combined with ceftriaxone on drug-resistant Salmonella

摘要:

【背景】由于抗生素的滥用，使得细菌耐药性问题严峻，寻找解决耐药性细菌感染的治疗策略迫在眉睫。临床上，中药与抗菌药物联用在抗耐药性细菌感染方面效果显著。【目的】研究香芹酚联合头孢曲松对耐药性沙门氏菌(SJ2)的协同效应及机制。【方法】通过二倍肉汤稀释法测定香芹酚和头孢曲松对SJ2的最小抑菌浓度(minimal inhibitory concentration, MIC)；通过棋盘法和生长曲线测定探究香芹酚和头孢曲松联合抗SJ2活性；通过膜电位检测、胞外碱性磷酸酶(alkaline phosphatase, AKP)含量测定、菌体内抗生素蓄积分析、细菌生存活力测定及扫描电镜研究香芹酚联合头孢曲松对SJ2细胞壁、细胞膜的影响。【结果】香芹酚和头孢曲松对SJ2的MIC分别为256 μg/mL和2 048 μg/mL；香芹酚联合头孢曲松对SJ2具有协同作用，其分级抑制浓度指数(fractional inhibitory concentration index, FICI)为0.375；香芹酚可协同头孢曲松使SJ2细胞膜出现去极化，显著增加AKP泄漏至胞外的量(P<0.05)，显著增加菌体胞内抗生素蓄积(P<0.01)，显著增加细胞膜完整性破坏的细菌数量，严重造成菌体结构的损伤。【结论】香芹酚联合头孢曲松具有协同抗SJ2的作用，其协同机制可通过损伤细菌细胞壁及细胞膜来实现。

Abstract:

[Background] Due to the abuse of antibiotics, bacterial drug resistance has become a severe problem. Therefore, it is urgent to find useful strategies to solve the current situation of drug-resistant bacterial infections. In clinical, the combination of Chinese medicine and antibiotics is significantly effective in preventing drug-resistant bacterial infections. [Objective] To study the synergistic effect of carvacrol combined with ceftriaxone on drug-resistant Salmonella (SJ2) and the mechanism. [Methods] The minimum antibacterial concentration (minimal inhibitory concentration, MIC) of carvacrol and ceftriaxone on SJ2 was determined by broth microdilution method. The activity of carvacrol combined with ceftriaxone against SJ2 was determined by checkerboard method and growth curve. The effects of carvacrol combined with ceftriaxone on SJ2 cell wall and membrane were studied by membrane potential detection, extracellular alkaline phosphatase (alkaline phosphatase, AKP) content determination, antibiotic accumulation analysis in bacteria, bacterial viability determination, and scanning electron microscopy. [Results] The MIC of carvacrol and ceftriaxone against SJ2 was 256 μg/mL and 2 048 μg/mL, respectively. The carvacrol and ceftriaxone had the synergistic effect on SJ2, and their fractional inhibitory concentration index (fractional inhibitory concentration index, FICI) was 0.375. Carvacrol combined with ceftriaxone depolarized the SJ2 cell membranes, and significantly increased the amount of extracellular AKP (P<0.05), the intracellular antibiotic accumulation (P<0.01), and the number of bacteria that disrupted cell membrane integrity and caused serious damage of structure. [Conclusion] Carvacrol combined with ceftriaxone has the synergistic effect against SJ2, and the synergistic mechanism can be realized by damaging the bacterial cell wall and cell membrane.