OBJECTIVE To observe the in vitro induced drug resistance mechanisms of polymyxin B-resistant Acin-etobacter baumannii and explore the in vitro antimicrobial activity of polymyxin B combined with melatonin.METHODS Totally 10 strains of polymyxin B-sensitive A.baumannii were clinically isolated from the Affiliated Li Huili Hospital of Ningbo university between Jan.2021 to Dec.2021 and were induced to the polymyxin B-resistant strains by means of in vitro induction method.The drug resistance mechanisms of the polymyxin B-resistant A.baumannii strains were explored by polymerase chain reaction(PCR)combined with sequencing analysis.The minimum inhibitory concentrations(MICs)of the single and joint use of polymyxin B and melatonin were detected by using broth microdilution checkerboard.The antibacterial effect of polymyxin combined with melatonin was e-valuated by calculating fractional inhibitory concentration index(FICI).The strains that showed the remarkable synergistic effect for the antimicrobial activity were chosen to determine the time-kill curves.RESULTS Among the polymyxin B-induced drug-resistant A.baumannii strains,there were gene mutations at various loci of polymyxin resistance genes pmrB,lpxA and lpxD.The MIC of polymyxin B against A.baumannii strains declined after the combined use of polymyxin B and melatonin.The combined use of the two drugs that showed synergistic effect for antimicrobial activity accounted for 80.00％(8/10),the additive effect 20.00％(2/10).The time-kill curve showed that the combined use of polymyxin B and melatonin showed remarkable antibacterial effect at the 24th hour.CONCLUSIONS The drug resistance gene mutations that are mediated by chromosomes are the major drug resist-ance mechanisms of the A.baumannii strains to polymyxin B.The combined use of polymyxin B and melatonin may reverse the drug resistance of the A.baumannii to polymyxin B.

OBJECTIVE To observe the in vitro induced drug resistance mechanisms of polymyxin B-resistant Acin-etobacter baumannii and explore the in vitro antimicrobial activity of polymyxin B combined with melatonin.METHODS Totally 10 strains of polymyxin B-sensitive A.baumannii were clinically isolated from the Affiliated Li Huili Hospital of Ningbo university between Jan.2021 to Dec.2021 and were induced to the polymyxin B-resistant strains by means of in vitro induction method.The drug resistance mechanisms of the polymyxin B-resistant A.baumannii strains were explored by polymerase chain reaction(PCR)combined with sequencing analysis.The minimum inhibitory concentrations(MICs)of the single and joint use of polymyxin B and melatonin were detected by using broth microdilution checkerboard.The antibacterial effect of polymyxin combined with melatonin was e-valuated by calculating fractional inhibitory concentration index(FICI).The strains that showed the remarkable synergistic effect for the antimicrobial activity were chosen to determine the time-kill curves.RESULTS Among the polymyxin B-induced drug-resistant A.baumannii strains,there were gene mutations at various loci of polymyxin resistance genes pmrB,lpxA and lpxD.The MIC of polymyxin B against A.baumannii strains declined after the combined use of polymyxin B and melatonin.The combined use of the two drugs that showed synergistic effect for antimicrobial activity accounted for 80.00％(8/10),the additive effect 20.00％(2/10).The time-kill curve showed that the combined use of polymyxin B and melatonin showed remarkable antibacterial effect at the 24th hour.CONCLUSIONS The drug resistance gene mutations that are mediated by chromosomes are the major drug resist-ance mechanisms of the A.baumannii strains to polymyxin B.The combined use of polymyxin B and melatonin may reverse the drug resistance of the A.baumannii to polymyxin B.

Objective:To observe the characteristics of back scraping skin symptoms in sub-health people through diagnostic scraping, and explore the characteristics of back scraping skin symptoms in sub-health people with different constitutions.Methods:By adopting a cross-sectional study method, the Third Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine recruited volunteers through a combination of offline and online methods from March 2021 to September 2022. Totally 2 239 sub-health people were treated for TCM constitution identification and were diagnostic scraped with Wentong scraping cup. The differences of back scraping skin symptoms in the color, speed, amount, shape, nature of pain and feeling characteristics under scraping board were compared between sub-health people with different TCM constitutions and gentle constitution.Results:There were differences in the characteristics of Sha Xiang among sub-health individuals with different constitutions. Among them, 49.02% (351/716) of individuals with a gentle constitution had a bright red color, 90.64% (649/716) had a fast rate of appearance, 5.73% (41/716) had a large amount of sha, 3.35% (24/716) had a patchy shape, 3.35% (24/716) felt a stabbing pain, and 0 felt nodules under the scraping plate. Among individuals with a damp-heat constitution, 86.72% (457/527) had a bright red color, 95.64% (504/527) had a fast rate of appearance, 100.00% (527/527) had a large amount of sha, 88.80% (468/527) had a patchy shape, 95.64% (504/527) felt a stabbing pain and 97.72% (515/527) felt nodules under the scraping plate. There was a statistically significant difference between the two groups ( χ2 values were 11.27 to 1 243.00, all P<0.05). Conclusions:The characteristics of back scraping skin symptoms of sub-health people with different constitutions are different. It is expected that the type of TCM constitution of sub-health people can be judged according to the characteristics of scraping skin symptoms in the future, in order to guide patients in health management and improve their satisfaction with traditional Chinese medicine scraping treatment.