Prevalence And Influencing Factors Of Klebsiella Pneumoniae Nasal Colonization Among Men Who Have Sex With Men In Guangzhou

ObjetiveTo determine the prevalence,risk factors,resistance phenotypic and molecular characteristics of Klebsiella pneumoniae（K.pneumoniae）nasal colonization in men who have sex with men（MSM）in Guangzhou,thus providing reference basis for prevention and control of Klebsiella pneumoniae transmission and infection in MSM.MethodsCross-sectional design and random sampling method were conducted in our study to enroll MSM in a large-scale HIV Voluntary Counseling Testing Clinic of Guangzhou.Nasal samples were collected from both anterior nares of participants while a questionnaire was completed by each enrolled participant.K.pneumoniae were identified by combining traditional laboratory test and automatic bacterial identification.Carbapenem-resistant Klebsiella pneumoniae（CRKP）was screened by antimicrobial resistance test,and Hypermucoviscous Klebsiella pneumoniae（HMKP）was isolated and identified by a string test.Antimicrobial resistance of all K.pneumoniae strains were tested by Kirby-Bauer disk diffusion and broth microdilution method.Polymerase Chain Reaction（PCR）assay was used to detect the antibiotics resistant genes,virulence genes and the capsular serotypes of K.pneumoniae.Multilocus sequence typing（MLST）was performed to identify the molecular type of all K.pneumoniae isolates.The chi-square test or Fisher’s exact test were used to explore the influencing factors of K.pneumoniae nasal colonization and nonconditional logistic regression models or exact logistic regression models were conducted to multivariate analysis.The differences of phenotypic characteristics,antibiotics resistant genes and virulence genes were compared by using chi-square test or Fisher exact test.Two-sided P values<0.05 were considered statistically significant.Burst algorithm and tree diagram analysis software such as Phyloviz 2.0 and Mega-X were used to analyze the evolutionary relationship between the strains.ResultsDemographic characteristic:A total of 911 MSM were enrolled in this study with age range from 16 to 58 years old.The average age was27.70±3.38 years old.Most of them were Chinese Han population（96.38%）,42.04%of them have Guangzhou household registration,86.72%of the MSM population has a college degree or above,and59.82%MSM were in-service staff.The prevalence and influencing factors of K.pneumoniae,CRKP and HMKP:Of the 911 MSM participants,20.09%（183/911）were colonized with K.pneumoniae.The prevalence of CRKP,HMKP and Carbapenem-resistant hypermucoviscous Klebsiella pneumoniae（CR-HMKP）strains were 9.66%（88/911）,1.65%（15/911）and 0.66%（6/911）,respectively.Multivariate analyses showed that age below 30years old（OR=1.496,95%CI:1.023-2.188）was a risk factor of K.pneumoniae nasal colonization.Keeping pets（OR=2.525,95%CI:1.242-5.682）and sometimes using condoms when having homosexual behavior in recent six months（OR=1.807,95%CI:1.071-3.030）were risk factors of CRKP nasal colonization among MSM.Antibiotic use in the last six months（a OR=3.973,95%CI:1.417-11.138）was a risk factor of HMKP colonization.Antimicrobial resistance:K.pneumoniae isolates had higher resistance to ampicillin（99.45%）,nitrofurantoin（93.99%）and ciprofloxacin（60.11%）.CRKP strains were completely resistant to ampicillin（100.00%）,followed by imipenem（96.59%）,nitrofurantoin（96.59%）and ciprofloxacin（71.59%）.Resistance rates of imipenem,meropenem,amikacin,ciprofloxacin and levofloxacin in CRKP isolates were statistically higher than that in Carbapenem-susceptible Klebsiella pneumoniae（CSKP）isolates（P<0.05）.The antibiotic resistance rates of HMKP and Non-hypermucoviscous klebsiella pneumoniae（Non-HMKP）isolates were all highest in ampicillin（100.00%vs.99.40%）,followed by nitrofurantoin（93.33%vs.94.05%）.There was no significant difference in antibiotic resistance rates between HMKP and Non-HMKP isolates.42.62%K.pneumoniae isolates among MSM were multidrug resistant strains.Compared with CSKP isolates,CRKP isolates experienced a higher multidrug resistance and the risk of multidrug resistance was 5.217times than CSKP（P<0.001）.Multidrug resistance pattern of CRKP was co-resistant to ampicillin,imipenem and nitrofurantoin.40.00%HMKP showed multidrug resistance and there was no significant difference in multidrug resistance when compared with Non-HMKP isolates.The predominant multidrug resistance pattern of HMKP was ampicillin,nitrofurantoin and ciprofloxacin.Genes detection:The most drug resistance genes was^blaSHV（78.14%）and qnr S（74.86%）of K.pneumoniae isolates while the most virulence genes was ent B（97.27%）and mrk D（95.08%）.Some resistance genes such as qnr A,tet（X）and mcr-1 weren’t detected.15.91%CRKP isolates carring carbapenem-resistant genes and it was observed that different carbapenem-resistant genes coexiested in the same CRKP strains.There were no statistically significant differences in drug resistance genes and toxin genes between CRKP and CSKP isolates.Except for^blaSHV（80.00%）and qnr S（60.00%）,the carrying rates of aac（6’）-Ib,IMP,aac（3）-II,KPC,^blaTEM,^blaCTX-M-1 and qnr B in HMKP strains were all lower than 20%,and there was no statistical significance in the carrying of drug-resistant genes between HMKP strains and Non-HMKP strains（P≥0.05）.The mrk D gene was detected in all HMKP isolates.Carriage of mag A,all S,iut A and rmp A genes in HMKP isolates were statistically higher than non-HMKP（P<0.05）.HMKP isolates were mainly serotype K1（20.00%）except that those non-typeable.MLST:A total of 114 STs were detected,and the most predominant STs for K.pneumoniae was ST23（12/183,6.56%）,while the main STs of CRKP were ST23,ST36 and ST37（all 5/88,5.68%）,and the predominant STs of HMKP was ST23（4/15,26.67%）.ConclusionBoth the prevalence of K.pneumoniae and CRKP nasal colonization were high among MSM in Guangzhou.Age below 30 years old was a risk factor of K.pneumoniae nasal colonization.Keeping pets and sometimes using condoms when having homosexual behavior in the last six months were risk factors of CRKP nasal colonization among MSM.Antibiotic use in recent six months was a risk factor of HMKP colonization.K.pneumoniae isolated from MSM in Guangzhou had higher resistance to tigecycline,while the multidrug resistance of CRKP strain was serious.The main STs of CRKP isolates among MSM were ST23,ST36 and ST37,which were different from ST11,the predominant STs of CRKP clinical isolates in China.