The purpose of this study was to reveal the resistance mechanism of Mycoplasma bovis from Xizang yaks to macrolide antibiotics and provide theoretical basis for clinical medication.In this study,10 strains of Mycoplasma bovis from Xizang yaks were tested for drug sensitivity to macrolide antibiotics using the micromethod,and sensitive strains were induced to be highly resist-ant in vitro.The results showed that all 10 strains of Mycoplasma bovis exhibited varying degrees of resistance to macrolide antibiotics.However,through methylation enzyme and inactivation en-zyme gene detection and analysis,it was found that there was no methylation enzyme encoded by the methylation enzyme gene and no resistance mechanism mediated by macrolide inactivation en-zymes,indicating that there were no mutations in the target gene loci of the sensitive and resistant strains.However,highly resistant strains in vitro have mutations at the domain Ⅱ,L22,and even L4 target gene loci,indicating that if two or more target gene amino acid loci undergo mutations,highly resistant strains can be produced.After testing with active efflux systems,it was found that there were no active efflux systems using macrolide antibiotics as substrates.It can be seen that the strain of Mycoplasma bovis from Xizang yaks is prone to mutation under the pressure of high con-centrations of macrolides,and there are mutations in two or more target gene amino acid sites,which is prone to produce highly resistant strains.

Objective:To explore the effect of comorbidities on the risk of chronic kidney disease with aging.Methods:A total of 103 682 subjects were recruited at the health management center of the First Affiliated Hospital of Nanjing Medical University from January 2018 to January 2020 for a retrospective cross-sectional study.Participants were divided into four groups according to age 18-44(55 055 case), 45-59(31 023 case), 60-74(12 793 case), ≥75(4 811 case)age group.We calculated and compared the prevalences of estimated glomerular filtration rate(eGFR)<60 ml/min/1.73m 2, which was used as a parameter for kidney dysfunction, indifferent age groups and participants with different comorbidities.The association between comorbidities and the prevalence of kidney dysfunction was analyzed by Logistic regression. Results:Levels of blood pressure, body mass index, serum creatinine, eGFR and blood lipids varied with aging, as did the prevalences of hypertension, diabetes, obesity and comorbidities.In all participants and groups based on the types of chronic diseases, the prevalence of kidney dysfunction increased with aging, substantially so in ≥75 age group.After adjustment for age and sex, there was a marked increase in the risk of kidney dysfunction in 45-59 age group adults with hypertension or diabetes( OR=9.163, 95% CI: 3.264-25.727; OR=4.640, 95% CI: 1.028-20.936), and the risk of renal dysfunction increased in people with hypertension+ diabetes or with the coexistence of three diseases, compared with people with a single disease( OR=16.441, 95% CI: 5.325-50.783; OR=15.985, 95% CI: 4.237-60.312); In the 60-74 age group, hypertension alone also significantly increased the risk of renal dysfunction( OR=3.950, 95% CI: 1.911-8.165). With comorbidities, the most significant influence was the coexistence of three diseases( OR=6.245, 95% CI: 2.521-15.468), followed by hypertension+ obesity( OR=5.640, 95% CI: 2.550-12.476)and hypertension+ diabetes( OR=4.330, 95% CI: 1.990-9.421); In ≥75 age group, chronic diseases and comorbidities were associated with a high risk of renal dysfunction, with obesity alone and hypertension obesity posing the highest risk( OR=6.746, 95% CI: 2.193-20.757; OR=6.570, 95% CI: 3.178-13.582), followed by the coexistence of three diseases( OR=4.749, 95% CI: 2.110-10.687). Conclusions:The prevalence of hypertension, diabetes, and obesity varies with aging.The effect of chronic diseases on the risk of chronic kidney disease with reduced renal function in the elderly population is different from that in the non-elderly population.