模拟微重力对医院获得性肺炎老年患者痰标本中泛耐药鲍曼不动杆菌表型的影响

Effects of simulated microgravity on the phenotype of extensively drug-resistant Acinetobacter baumannii exstracted from sputum specimens of elderly patients with hospital-acquired pneumonia

目的研究模拟微重力对从医院获得性肺炎老年患者痰标本中分离出来的泛耐药鲍曼不动杆菌表型的影响。方法利用微重力三维细胞培养系统建立鲍曼不动杆菌模拟微重力株,同时建立正常重力株作为对照组,利用Bioscreen观察两菌株的生长速度,通过涂抹平板计数法对两菌株进行菌落计数,通过观察两菌株在含有5 mmol/L过氧化氢(H2O2)的磷酸盐缓冲溶液中存活率研究两菌株的氧化应激性,通过结晶紫染色法观察两菌株的生物膜形成能力,通过K-B纸片法观察两菌株的抗生素敏感性。结果与正常重力株比较,模拟微重力株生长速度减慢,尤其是在10 h以后;平板菌落计数结果显示,与正常重力株比较,模拟微重力株生长受到抑制,菌落数为(2.33±0.61)×10^13CFU/L比(4.87±0.63)×10^13CFU/L(t=4.865,P=0.040);模拟微重力株在H2O2溶液中存活率降低,为(51.43±0.97)%比(56.53±2.54)%(t=4.715,P=0.042);模拟微重力株生物膜形成能力下降,吸光度(A)570值为0.449±0.014比0.506±0.024(t=8.692,P=0.013);阿米卡星对模拟微重力株的抑菌环直径(15.17±0.21)mm,比正常重力株(13.77±0.15)mm增加(t=6.725,P=0.021)。结论模拟微重力使泛耐药鲍曼不动杆菌的生长速度、氧化应激性、生物膜、抗生素敏感性发生了改变,这种现象可以为泛耐药鲍曼不动杆菌相关的医院获得性肺炎老年患者的治疗提供新策略。

Objective To investigate the effects of simulated microgravity on the phenotype of extensively drug-resistant Acinetobacter baumannii extracted from sputum specimens of elderly patients with hospital-acquired pneumonia.Methods A strain of A.baumannii grown in simulated microgravity was constructed by a three-dimensional rotary cell culture system,and a strain of A.baumannii grown in normal gravity was prepared as a control group.The growth rates of the two strains were detected by the Bioscreen system,colony numbers were measured by the plate colony-counting method,oxidative stress was analyzed by observing the survival rate in phosphate buffer saline(PBS)with 5 mmol/L H2O2,biofilm formation ability was determined by crystal violet staining,and antibiotic susceptibility was measured by the K-B method.Results Compared with the normal gravity strain,the simulated microgravity strain was associated with a significantly slower growth rate,especially after 10 h(P<0.05),a decreased number of bacterial colonies[(2.33±0.61)×10^13CFU/L vs.(4.87±0.63)×10^13CFU/L,t=4.865,P=0.040],lower survival rates in PBS solution with H2O2[(51.43±0.97)%vs.(56.53±2.54)%,t=4.715,P=0.042],reduced biofilm formation ability(A570),[(0.449±0.014)vs.(0.506±0.024),t=8.692,P=0.013],and an increased inhibition zone diameter of amikacin[(15.17±0.21)mm vs.(13.77±0.15)mm,t=6.725,P=0.021].Conclusions Simulated microgravity changes the growth rate,biofilm formation ability,oxidative stress and antibiotic susceptibility of extensively drug-resistant A.baumannii,potentially providing a new treatment strategy for extensively drug-resistant A.baumannii-associated hospital-acquired pneumonia in the elderly.