Antibiotic Resistance And Molecular Subtyping Of Vibrio Parahaemolyticus In China During 2002 To 2017

Objective:To determine the antibiotic resistance of Vibrio parahaemolyticus in China,and analysis the relationship between antibiotic resistance and molecular subtyping.Methods:tdh and trh was amplified by PCR.The disk diffusion susceptibility testing was performed on 1575 V.parahaemolyticus strains that were isolated in China during 2002 to 2017.Sequence analysis of antibiotic resistance gene of some MDR strains.438 V.parahaemolyticus strains isolate from different regions in China were used to evaluate VNTRs of V.parahaemolyticus Comparing the use of MLVA with MLST for subtyping to analysis the relationship between antibiotic resistance and molecular subtyping.Results:1、78.73%(1240/1575)and 3.37%(53/1575)of the tested strains were positive for tdh and trh respectively.The positive rate(82.41%,4.05%)in clinical isolates was higher than in environment isolates(68.43%,1.45%).2、High resistant rates were found to be 85.33%,53.52%and 30.29%for ampicillin,sulfamethoxazole and streptomycin,respectively.Low susceptible rate to kanamycin(65.52%),ciprofloxacin(45.27%),cefepime(33.21%)and cefoxitin(33.21%)was also observed.The susceptible rates of other antibiotics were above 90%.19.75%(311/1575)of the tested strains showed multidrug resistance.3、The antibiotic resistance gene blaCARB,tet34,tet35 and crp of RND efflux pump was detectable.4、The resistant rates of ceftriaxone,cefepime,trimethoprim/sulfamethoxazole and sulfamethoxazole in clinical isolates were lower than environmental isolates;and the resistant rate of azithromycin was higher than environment isolates.The resistant rates of streptomycin,kanamycin and sulfamethoxazole in tdh-strains were higher than tdh+strains.5、The resistant rates and the MDR rate(6.25%)were low except ampicillin before 2007.But all kinds of antibiotic resistance to drugs has increased significantly since 2007.The resistant rates of ceftriaxone(21.74%),cefepime(8.70%),azithromycin(39.13%),ciprofloxacin(34.78%),nalidixic acid(4.35%)reached to the highest level in 2008.After 2008,the resistance of the strain to all kinds of antibiotics showed a decline trend.But the drug resistant rate showed a significant rebound in recent years.6、The drug-resistant spectrum of isolates in Beijing is narrower than that in Shanghai and Shenzhen.The susceptible rates to cefoxitin,ceftriaxone,cefepime,ciprofloxacin,nalidixic acid,sulfamethoxazole and trimethoprim/sulfamethoxazole of isolates in Shenzhen was far lower than that in Shanghai and Beijing.The susceptible rate to streptomycin of isolates in Beijing was far lower than that in Shanghai and Shenzhen.7、The amplification rate of VPTR7 was 71.90%,and of other 11 VNTRs were above 94%.Locus VP 1-17 showed no polymorphism.Locus VP2-07 showed excessive polymorphism and variable in the process of culturing.We established six-locus MLVA(VP 1-10,VP 1-11,VPTR1,VPTR4,VPTR5 and VPTR6)for V.parahaemolyticus subtyping in China。8、No correspondence between MLST subtyping,MLVA subtyping and antibiotic resistance phenotype was found.Conclusion:1、Penicillin,sulfamethoxazole and aminoglycoside should not be used to treat V:parahaemolyticus.V parahaemolyticus has sophisticated mechanism of drug resistance.There are differences in the drug resistant spectrum of V.parahaemolyticus isolate from different sources and different areas.2、The six-locus MLVA(VP1-10,VP1-11,VPTR1,VPTR4,VPTR5 and VPTR6)for V.parahaemolyticus subtyping show higher discriminatory power than MLST.3、No correspondence between specific sequence type,genotype and antibiotic resistance phenotype was found.