The Study On The Virulence And Resistance Ofaeromonas In The Yellow River Drainage Basin Of Henan

Water resources of the Yellow River drainage basin is rish in Henan Province.The Yellow River basin is an important aquaculture area in province.The growing frequency of fish disease has severely hindered the sustainable development of aquaculture with the intensive aquaculture.Aeromonas,belonging to Aeromonas genus in the family Aeromonas.It can cause a variety of aquatic animals arise bleeding,ulceration and enteritis with high morbidity and mortality.The pathogenic process of Aeromonas is closely related to the various virulence factors that produced.The genes encoding these virulence factors have been widely used to determine the potential pathogenicity of the genus Aeromonas.Antimicrobial agents play a role in the treatment of bacterial diseases in aquaculture animals,and the unscientific use of has led to aggravation of drug resistance and multidrug resistance in Aeromonas.Understanding the virulence and drug resistance of Aeromonas can lay a foundation for early warning of Aeromonas disease and finding safe and effective prevention and control methods.In this paper,the seasonal distribution of Aeromonas in the culture pond was tested,and the virulence and drug resistance of Aeromonas in the Yellow Sea fishing area in Henan Province were analyzed.The main results were as follows:1.Seasonal Distribution of Aeromonas in Aquaculture pondsThe seasonal distribution of Aeromonas in water samples from aquaculture ponds was detected by16S-RFLP.The number of Aeromonas in aquaculture pond varies with temperature.In 7⁸ months,the number reached the highest（7×10³ cfu/mL）,and the number reached the lowest in 1² month（3×10²cfu/m L）.A total of 8 Aeromonas species were identified,which were A.veronii,A.sobria,A.caviae,A.hydrophila,A.salraonicida,A.media,A.jandaei and A.culicicola,which A.veronii was the dominant species in spring,summer and autumn accounted for 80%,90%,95%,and the proportion of A.veronii was reduced to 64%,and the number of A.salmonicida increase to 22%in winter.2.The virulence of Aeromonas in Yellow River Fishing Area in Henan ProvinceDetection of 10 virulence genes act,ast,alt,aer,hly,lip,omp,fla,ela,and ahpA by PCR in 269Aeromonas spp.isolated from Yellow River in Henan Province.The Aeromonas has detected at least one virulence gene,The aer,lip,act,fla,omp,and ela gene detection rates of total Aeromonas gene were 89%,86%,84%,79%,78%,and 59%,respectively.There is no significant difference in the distribution of this 6virulence genes in diseased fish,infected pool water and non-pathogenic pools of Aeromonas.The detection rates of the virulence genes ast,alt,hly,and ahpA in diseased fish and infected pool water were higher than those in non-pathogenic pools of Aeromonas.Among the three sources of Aeromonas,97%of Aeromonas had both hemolytic activity and protease activity.Ten virulent strains(LD₅₀<10⁶ cfu/tail)were distributed in the diseased fish,and both the infected pool water and non-pathogenic pools of Aeromonas were all attenuated strains(LD₅₀≥10⁶ cfu/tail).The virulence of different virulence genotypes of Aeromonas is different.Aeromonas which carrying ast,alt,aer,hly and ahpA virulence genes belong to virulent strains.3.Resistance of Aeromonas in Yellow Fishing Area along Henan ProvinceDrug Sensitive Paper Method for detecting the sensitivity of Aeromonas in 8 types of 20 antibacterial drugs in Yellow Fishing area along Henan province.The resistance rates of diseased fish,infected pool water and non-pathogenic pools of Aeromonas to penicillin G and ampicillin were 100%,and the resistance rates to tetracycline,doxycycline and nalidixic acid were all over 30%.The 90.4%of Aeromonas resistant to more than 3 kinds of antibacterial drugs.There were 45 drug resistance profiles,of which the proportion of resistant PG/AMP/DOX was the highest（12.3%）.The detection rate of drug resistance gene bla_TEMEM was the highest（100%）,followed by the detection rates of ant（3’’）-I,flor,tetE,tetA,qnrS,sul2 were 99%,28%,23%,8%,12%,6%,respectively.The strain carrying the bla_TEMEM gene was 100%resistant to penicillins,and the tetA gene was 100%resistant to tetracyclines.The detection results of these two resistant genes were consistent with the drug resistant phenotypes;The resistance phenotypes of tetracyclines,sulfonamides,quinolones,aminoglycosides,and amido alcohols carrying the drug resistance genes tetE,sul2,qnrS,ant（3’’）-I and flor were not identical.4.The ERIC classification of A.veronii in Yellow Fishing Area along Henan ProvinceThe type of A.veronii was studied by ERIC-PCR in Yellow Fishing Area along Henan Province.It was found that the ERIC classification of A.veronii showed good polymorphism.The origin of the strains in each type of ERIC was different.The virulent and attenuated strains showed cross distribution,and were distributed in the same ERIC type,with the same virulence genotype of Aeromonas were virulent strains.A.veronii with the similar ERIC typing has similar resistance spectrum.In this study,we studied the virulence and drug resistance of Aeromonas in areas along the Yellow River in Henan,providing basic data for the early warning and prevention of diseases caused by Aeromonas bacteria and the rational use of antibiotics in aquaculture production.