鲍曼不动杆菌体外诱导耐药及其诱导前后交叉耐药和呼吸耗氧率分析

Intermediate resistance development in Acinetobacter baumannii in vitro and analysis of bacterial respiratory

摘要:

【背景】鲍曼不动杆菌是院内感染的重要病原菌，因其耐药率高、治疗难度大而备受关注。然而，对于该菌的交叉耐药及耐药相关因素尚未完全阐明。【目的】通过体外诱导分别获得耐美罗培南或耐替加环素的鲍曼不动杆菌菌株，并研究其诱导前后的交叉耐药性和细菌呼吸耗氧率差异。【方法】采用多步法对鲍曼不动杆菌ATCC19606进行体外诱导耐药，PCR扩增诱导前后菌株的16S rRNA基因并测序鉴定，微量肉汤稀释法检测诱导前后鲍曼不动杆菌对美罗培南、亚胺培南、替加环素、阿米卡星、头孢吡肟及左氧氟沙星等抗菌药物的最低抑菌浓度变化，Seahorse XFe96细胞能量代谢实时测定仪对诱导前后菌株的耗氧率进行分析。【结果】通过88 d的体外诱导实验，分别获得耐美罗培南或耐替加环素的鲍曼不动杆菌ATCC19606菌株。耐美罗培南鲍曼不动杆菌ATCC19606对替加环素、亚胺培南、阿米卡星、左氧氟沙星仍处于敏感状态，但是对头孢吡肟交叉耐药；耐替加环素鲍曼不动杆菌ATCC19606对美罗培南、亚胺培南、阿米卡星、左氧氟沙星及头孢吡肟仍处于敏感状态。鲍曼不动杆菌ATCC19606被美罗培南或替加环素诱导耐药之后的耗氧率均下降，差异均具有统计学意义。【结论】美罗培南的使用不仅可能诱导鲍曼不动杆菌ATCC19606对美罗培南耐药，也可能会导致该菌对其它一种或几种抗菌药物产生交叉耐药。鲍曼不动杆菌ATCC19606对美罗培南或替加环素耐药后其耗氧率下降，从而说明呼吸耗氧率下降可能是该菌耐药的因素之一。

Abstract:

[Background] Acinetobacter baumannii is an important pathogen of nosocomial infection, which has attracted much attention due to its high drug resistance rate and difficulty in treatment. However, the cross-resistance and the factors related to drug resistance of this bacterium have not been fully elucidated. [Objective] In order to study the cross-resistance and the differences of respiratory oxygen consumption between Acinetobacter baumannii resistant to meropenem or tigecycline and Acinetobacter baumannii sensitive to them, Acinetobacter baumannii was intermediated in vitro with meropenem or tigecycline. [Methods] Meropenem and tigecycline susceptible Acinetobacter baumannii ATCC19606 was induced resistance in vitro, and sequenced PCR products of 16S rRNA of strains before and after drug induction. The minimal inhibitory concentrations (MIC) of meropenem, imipenem, tigecycline, amikacin, cefepime and levofloxacin were determined by a broth microdilution method. Bacterial respiration before and after drug induction, expressed as oxygen consumption rate, was quantified using Seahorse XFe96 extracellular flux analyzer. [Results] Through a 88 d in vitro induction experiment, strain of Acinetobacter baumannii ATCC19606 resistant to meropenem or tigecycline was obtained, respectively. Meropenem-resistant Acinetobacter baumannii ATCC19606 was still sensitive to tigecycline, imipenem, amikacin and levofloxacin, but was cross-resistant to cefepime. Tigecycline-resistant Acinetobacter baumannii ATCC19606 was still sensitive to all antimicrobial agents tested. After Acinetobacter baumannii ATCC19606 was induced by meropenem or tigecycline respectively, the oxygen consumption rate decreased, and the difference was statistically significant. [Conclusion] The use of meropenem may not only induce resistance to meropenem in Acinetobacter baumannii ATCC19606, but also may cause cross-resistance of the bacterium to one or more other antimicrobial agents. The oxygen consumption rate of Acinetobacter baumannii ATCC19606 decreased after its resistance to meropenem or tigecycline, suggesting that the decrease in oxygen consumption rate may be one of the factors contributing to the resistance of this bacterium.