Colonization Characteristics Of Coagulase-Negative Staphylococcus Among Men Who Have Sex With Men In Guangzhou

ObjectiveTo investigate the prevalence,influencing factors,antimicrobial susceptibility and molecular characteristics of Coagulase-negative staphylococci(CoNS)and Methicillin-resistant Coagulase-negative staphylococci(MRCoNS)among men who have sex with men(MSM)in Guangzhou,thus providing scientific basis for the effective prevention and control of CoNS and MRCoNS nasal colonization and infection in MSM.MethodsCross-sectional study and random sampling methods were conducted to recruit MSM in the HIV Voluntary Counseling Testing Clinic in Guangzhou,between April to August 2019.All MSM were requested to complete a questionnaire to collect epidemiological information and nasal samples were obtained from both anterior nares.A series of traditional microbiologic assays were used to isolate and confirm CoNS;antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method;genotypic analyses of all CoNS isolates included the specific genes,antibiotic-resistant genes,virulence genes and Staphylococcal Cassette Chromosome mec(SCCmec)genotyping by using the Polymerase Chain Reaction and gel electrophoresis assay.The prevalence of nasal colonization and the proportions of antibiotic resistance and genes in MSM were described by rates;Pearson’s Chi-square test or Fisher’s exact test were used to assess the influencing factors of CoNS and MRCoNS colonization and P value<0.1 was further considered for multivariate analysis by non conditional Logistic regression model.Chi-square test or Fisher’s exact test were also conducted to determine the significance difference between antibiotic resistance and genetic characteristics among the different isolates.The associations of phenotypic and genotypic characteristics were also assessed by Logistic models and presented with prevalence and 95%confidence interval.Correspondence analysis was used to analyse the relationship between the number of resistant antimicrobial agents and the number of drug-resistant genes.All statistical tests were performed by Stata16.0,and P value of<0.05(bilateral tests)was defined as statistical significance.ResultsDemographic information:A total of 911 MSM were included,with an average age of 27.70±3.38 years(ranged from 16-58 years).91.55%MSM were unmarried,and 86.72%education background was college degree or above.705(77.39%)MSM were self-aware that they were homosexual,and788(86.50%)of them had homosexual behavior in recent 6 months.The prevalence and risk factors of CoNS and MRCoNS:Prevalence of CoNS and MRCoNS nasal colonize in MSM was 90.12%(821/911)and53.24%(485/911),respectively.From the results of multivariate analysis,students and employed MSM were 5.16 times(P=0.019,95%CI:1.31-20.30)and 4.31 times(P=0.007,95%CI:1.48-12.52)more easily to colonize CoNS in their nasal cavities.HIV-positive and those who had a history of using antimicrobial agents in the past 6 months were risk factors for MRCoNS nasal colonization.Those who were HIV-positive was 2.59 times(P=0.047,95%CI:1.01-6.60)riskier to become MRCoNS carriage.And those who had a history of using antimicrobial agents within previous 6 months were 1.89 times(P<0.001,95%CI:1.32-2.70)more likely to colonize MRCoNS.Antimicrobial susceptibility:A total of 947 CoNS isolates were identified from 911 MSM.The most predominant resistant antibiotic for CoNS isolates was penicillin(81.10%),erythromycin(68.85%),clindamycin(42.45%)and teicoplanin(33.37%),but the lower drug resistance rate was observed in linezolid(4.22%)and rifampici(2.32%).The proportions of antibiotic resistance of MRCoNS were higher than Methicillin susceptible coagulase-negative Staphylococci(MSCoNS)in the 12 antimicrobial agents,and resistance rates between MRCoNS and MSCoNS isolates were all significant except for lineczolid and rifampicin(P<0.05).The proportions of multidrug-resistant MRCoNS isolates were significantly higher than MSCoNS(OR=4.01,95%CI:3.05-5.29).65.79%CoNS isolates were Multidrug-resistant coagulase-negative staphylococci(MDRCoNS),and the predominant multidrug-resistant pattern of MDRCoNS isolates was non-susceptible to penicillin,erythromycin,and cefoxitin(31.68%).Virulence genes and antibiotics resistant genes detection of CoNS:The proportions of virulent genes sak(71.12%vs.69.37%)、scn(1.94%vs.2.78%)and tst(1.36%vs.1.16%)for MRCoNS were higher than MSCoNS isolates,but there was no significant difference.The most predominant resistant genes were bla Z(68.08%),lin A(25.00%)and erm(C)(22.87%).The proportions of resistance genes for MRCoNS was higher than MSCoNS except for lin A gene,and there were significant differences in the proportions of mec A,bla Z,aac(6’)-aph(2’’),erm(C),and tet(K)genes(P<0.05).The proportions of virulent genes scn for Non-MDRCoNS isolates were significantly higher than MDRCoNS(3.55%vs.1.45%,P<0.05).CoNS and MRCoNS isolates that were positive for erythromycin-,tetracycline-,gentamicin-,and penicillin-resistance genes had significantly higher rates of resistance to corresponding antibiotics(P<0.001).The number of antimicrobial agents of CoNS was in good corresponding relationships with the number of resistant genes(χ~2=221.19,P<0.001),the number of resistance to 5-6 antibiotic agents was associated with carring 3 resistance genes,and resistance to>6 antibiotic agents was associated with carring 4-6 resistance genes.SCCmec typing:Among SCCmec types,36.63%MRCoNS showed single type,the predominant SCCmec type was type III(8.53%),type IV(7.17%)and type V(6.40%).32.95%of the isolates showed combination type,mainly include type I+IV(8.91%),type II+V(5.81%)and type I+IV+V(4.46%).In addition,the non-typeable SCCmec of MRCoNS were accounted for 37.60%.There were significant differences in different SCCmec types between levofloxacin resistance rates(P=0.017),the resistance rates of non-typeable(33.12%)and combination SCCmec type(38.85%)were higher.Different SCCmec types showed significant differences in the proportions mec A,bla Z,erm(A)and lin A gene(all P<0.05).The proportion of mec A(39.71%vs.33.14%)、bla Z(37.40%vs.33.33%)and lin A(24.03%vs.46.51%)genes were shown higher in non-typeable and combination SCCmec type,but erm(A)gene was found higher in SCCmec type IV(50.00%).ConclusionsThis study highlights high prevalence of CoNS and MRCoNS nasal carriage among MSM.HIV-positive and those who had a history of using antimicrobial agents in the past 6 months were risk factors of MRCoNS nasal colonization.The multidrug-resistant of CoNS isolates from MSM is at a high level in the world,and the predominant multidrug-resistant pattern was non-susceptible to penicillin,erythromycin,and cefoxitin.MRCoNS isolates were mainly carring virulent genes sak,scn and tst,resistance genes bla Z,lin A and erm(C).MRCoNS isolates that were positive for resistance genes had higher rates of resistance to corresponding antibiotics.The predominant SCCmec type was type III of MRCoNS isolates,and there were many SCCmec combination types,among which SCCmec I+IV is the main one.