Effects of simulated microgravity on the phenotype of extensively drug-resistant Acinetobacter baumannii exstracted from sputum specimens of elderly patients with hospital-acquired pneumonia / 中华老年医学杂志

ABSTRACT

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 H 2O 2, 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 H 2O 2[(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.