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Virulence Gene Distribution And Antimicrobial Resistance Research Of Aeromonas From Different Sources In Hangzhou

Posted on:2017-06-13Degree:MasterType:Thesis
Country:ChinaCandidate:Y WanFull Text:PDF
GTID:2334330512473035Subject:Clinical Laboratory Science
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ObjectiveAeramonas was widely exists in nature,especially in the water environment,it can infect fish,birds,insects,mammals and other animals,can also lead to human intestinal infection and parenteral infection.The Aeromonas has become one of the common pathogens of summer diarrhea in China.As a water-borne and food-borne pathogen,it has been widely popular and often causes outbreaks,which threaten public health seriously.The distribution and drug resistance characteristics of Aeromonas were reported in many regions of the world.However,there are few reports on the research of Aeromonas in China.The drug resistance and virulence gene distribution of the isolates from intestine,parenteral and fish shellfish infected Aeromonas in Zhejiang was little understood.Therefore In this study we detected 19 virulence genes and antimicrobial resistance of intestine,parenteral and fish shellfish infected Aeromonas isolates that collected from Hangzhou,Zhejiang Province during July,2011 to June,2013.The results of intestine,parenteral and fish shellfish infected Aeromonas were also compared and the relationship between virulence genes and drug resistance was also explored in order to provide a reference for the clinical control and treatment of Aeromonas infection and lay the foundation for the study of the virulence genes and drug resistance of Aeromonas.MethodsStool specimens of outpatient and emergency acute diarrhea patients from Zhejiang University School of Medicine Affiliated First Hospital were collected during the period of May 2012 to 2013 September;the drainage fluid,pleural effusion,bile,Sputum and other specimens of hospitalized patients were also collected during the period of 2011-2013 years;retail shellfish(scallops,clams,razor clam,etc.)of seafood market were also collected during the period of 2011-2013 years.Aeromonas of those smaples were Isolated,identified and strain preserved.The antimicrobial susceptibility test was carried out by using disk diffusion method(KB method).The 19 virulence genes of the isolates were detected by PCR,and the infection of gut in the intestine,intestine and fish and shellfish were detected by PCR.The relationship between virulence virulence genes and drug resistance were discussed.Those results of intestinal,parenteral and fish shellfish infected Aeromonas were compared and the relationship between virulence genes and drug resistance was also explored.Results1.A total of 73 strains of Aeromonas were isolated from the stool samples of diarrhea patients,and 77 strains of Aeromonas were isolated from the specimens of drainage fluid,pleural effusion,bile,Sputum and other paraintestinal specimens.79 strains of Aeromonas were isolated from the shellfish samples.The results of biochemical phenotypic classification showed that Aeromonas aeruginosa(37 strains,50.6%)were the main pathogens in the intestinal strains,followed by Aeromonas hydrophila(28.8%)and Aeromonas sobria(17.8%).Aeromonas hydrophila(38 strains.49.3%)and Aeromonas aeruginosa(33.8%)were the main pathogens of parenteral infections;the Aeromonas sobriar(56.9%)and the Aeromonas salmonicida(36.7%)were the main pathogens of the environmental sources of Aeromonas.2.Of the intestinal infected isolates,the fla gene(63 strains,86.3%),the gcat gene(60 strains,82.2%),the Exu gene(50 strains,68.5%),the lip gene(35 strains,47.9%),the ahyB gene(35 strains,47.9%),have a higher detection rate.aerA gene(5 strains,6.8%),aexT gene(6 strains,8.2%),ascv2 Gene(7 strains,9.6%),ascV gene(8 strains,11.0%),have a lower detection rate.No tapA gene was detected.3.Of the paraintestinal infected isolates the gcat gene(70 strains,90.9%),the fla gene(60 strains,77.9%),lip gene(60 strains,77.9%),Exu gene(55 strains,71.4%),ahyB gene(43 strains,55.8%),EprCAL gene(43 strains,55.8%)and hlyA gene(39 strains,50.6%),have a higher detection rate,the tapA gene(8 strains,10.4%),ascv2 gene(8 strains,10.4%AexT gene(8 strains,10.4%),ascV gene(10 strains,13.0%)have a lower detection rate.4.Of the environmental sources infected isolates,the gcat gene(70 strains,88.6%),fla gene(53 strains,67.1%),alt gene(47 strains,59.5%),lip gene(41 strains,51.9%),ahyB gene(39 strains,49.4%)have a higher detection rate.The aerA gene(4 strains,5.1%),ascV gene(7 strains,8.9%)have a lower detection rate.No tapA gene was detected.5.There were no significant differences in the detection rates of the act gene,ascF-G gene,ascV gene,gcat gene,ahyB gene,aopP gene among the intestinal,parenteral,and environmental-derived aeromonas strains.The aerA gene,hlyA gene and the lip genes in the strains of extra-intestinal aeromonas was significantly higher than that in the intestinal and environmental sources.The detection rate of ascv2 gene and aexT gene in the strains of environmental sources was significantly higher than that of intestinal and environmental source strains.6.Of the intestinal infected isolates,ampicillin-sulbactam(90.41%)and amoxicillin-clavulanic acid(86.30%)have the highest resistance rates,while the resistance rate of piperacillin-tazobactam was only 9.59%.The resistance rate of Cefamedin(first-generation cephalosporin)was up to 76.71%,while the resistance rate of cefuroxime(second-generation cephalosporins);cefotaxime,ceftriaxone,ceftazidime(third-generation cephalosporins)and cefepime Oxime(fourth generation cephalosporins)were all less than or equal to 9.59%.The resistant rate of ciprofloxacin was 15.07%,and levofloxacin was 8.22%.The resistance rates of cefoxitin was 54.79%and tetracycline was 42.47%.The drug resistance rates of other tested types of antibiotics were much lower.7.Of the paraintestinal infected isolates the highest resistance rates of ampicillin-sulbactam and amoxicillin-clavulanic acid were 97.40%and 96.10%respectively,while the resistance rate of piperacillin-tazobactam was 31.17%.The resistance rate of Cefamedin(first-generation cephalosporin)was as high as 88.31%,and the resistance rate of cefuroxime(second generation cephalosporin)was 41.56%,which was significantly higher than that of intestinal infected isolates.The resistance rate of cefotaxime(35.06%),ceftriaxone(35.06%),ceftazidime(28.57%)(third-generation cephalosporins)and cefepime(18.18%)(fourth-generation cephalosporins)were also much higher.The resistance rates of other tested antimicrobial agents were significantly higher than that of the intestinal source Aeromonas.8.Of the environmental sources infected isolates,the resistance rates of ampicillin-sulbactam and amoxicillin-clavulanic acid were 67.09%and 69.62%,respectively,while the resistant rate of piperacillin-tazobactam was 2.53%.The resistance rate of Cefamedin(first-generation cephalosporin)was up to 60.76%,while the resistance rate of cefuroxime(second-generation cephalosporins);cefotaxime,ceftriaxone,ceftazidime(third-generation cephalosporins)and cefepime Oxime(fourth-generation cephalosporins)were all less than or equal to 7.59%.In addition to the amikacin(24.05%),cefoxitin(18.99%)and tetracycline(16.46%)have a high resistance rates,the resistance rates to other antimicrobial agents were all very low.9.There was a high resistance rate(>60.76%)to penicillins and first-generation cephalosporins(cefazolin)of the intestinal,parenteral,and environmental-derived aeromonas strains.The resistance rates of the second-generation cephalosporins(cefuroxime,41.56%)and the third-generation cephalosporins(cefotaxime(35.06%),ceftriaxone(35.06%),ceftazidime(28.57%))and the fourth-generation cephalosporins(cefepime(18.18%))and the resistance rate of levofloxacin and ciprofloxacin were higher in intestinal-derived aeromonas strains than that of parenteral and environmental derived aeromonas strains.Amikacin’s resistant rate was significantly higher in environmental-derived aeromonas strains than that of the intestinal and parenteral derived strains.10.The strains of ahyB,lip,Exu,eprCAL,fla gene positive aeromonas strains have higher drug-resistant rates to second-generation cephalosporins(cefuroxime),third-generation cephalosporins(cefotaxime,ceftriaxone,ceftazidime),levofloxacin,ciprofloxacin and Cotrimoxazole than the negative aeromonas strains;while the laf,aexT and ascF-G gene positive strains have lower drug-resistant rates to second-generation cephalosporins(cefuroxime)(Cefotaxime,ceftriaxone,ceftazidime),levofloxacin and ciprofloxacin than the negative aeromonas strains.Conclusions1.Aeromonas aeruginosa was the main pathogens of intestinal infection in this region,while Aeromonas hydrophila and Aeromonas Aeromonas caviae were the main aeromonas of parenteral infection,the Aeromonas sobria and Aeromonas salmonicida were the main aeromonas of The environmental Aeromonas;.2.The gcat,act,fla,ahyB gene widely exists in different sources of Aeromonas;aerA,hlyA and lip were higher in paraenteral infected strains;the ascv2 and aexT genes were higher in fish-shellfish infected strains;3.The resistance rate of penicillins and first-generation cephalosporins in the intestine,parenteral and fish-shell infected aeromonas were all quiet high;Resistance rates of second/third-generation cephalosporins,ciprofloxacin and levofloxacin were relatively higher in parenteral infected strains.Amikacin’s resistant rate was relatively higher in environmental-derived aeromonas strains.4.ahyB,lip,Exu,eprCAL,Fla gene may contribute to resistance of second/third generation cephalosporins,levofloxacin,ciprofloxacin,cotrimoxazole;laf,aexT,ascF-G gene maybe inhibit the resistance of second/third generation cephalosporins,levofloxacin,ciprofloxacin,cotrimoxazole.
Keywords/Search Tags:Aeromonas, PCR, virulence gene, drug resistance
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