Study On Clinical Characterization And Biological Characteristics Of Waterfowl Salmonellosis

Salmonellosis is one of the common bacterial diseases in waterfowl.In recent years,the incidence of Salmonella is increasing and its clinical manifestations are diversified.In order to understand the infection of Salmonella in waterfowl,the clinical features of the sick wate-rfowl,the distribution of serotype,molecular typing,drug resistance and the prevalence of drug-resistant genotypes of pathogenic bacteria in Guangdong,then to search the relationshi-p between clinical characterization and serotypes,serotypes and molecular typing,drug resi-stant phenotype,drug-resistant genotypes,molecular typing,and so on.In the study,the clin-ical characterization of Salmonellosis of waterfowl in Guangdong was summarized and clas-sified,and the serotype,molecular typing,drug resistance and resistance genes of Salmo-nella were detected and analyzed.In this study,110 cases of Salmonella infected with Salmonella were classified and ide-ntified as salmonella cases in parts of Guangdong during 2013²017,then selected 8 repres-entative strains of serotypes for the artificial infection test of 10 days-old goose,to observe the clinical features and histopathological changes of the artificial goose.The results were that in the artificial pathogenic test,8 serotype strains were inoculated with the acute aborti-on type,which was characterized by liver swelling and necrosis;in natural cases,most of the young waterfowl mainly showed acute blood loss and liver green atrophy,the clinical manif-estations of the sick waterfowl were divided into acute liver necrosis,chronic onset,green atrophy and chronic liver swelling and sclerosis;at the same time,both the young waterfowl and the species of waterfowl have acute disease type characterized by cellulose pericarditis and liver pericarditis.These showed that the clinical characterization of waterfowl Salmone-llosis is diverse,and it was not directly related to the serotype of patho-genic bacteria,and there were different manifestations of poultry infected with age,resistance,production status and feeding environment.However,the pathogenicity of Salmonella with different serotypes was significantly different.The study,using conventional methods and PCR amplification technology,had success-fully isolated and identified 188 kinds of Salmonella strains of waterfowl from 316 disease materials about sick waterfowl included 166 kinds from geese,22 kinds from duck,with the detection rate of 59.49%,the disease materials were submitted for inspection from 238 Wate-rfowl plants in Guangdong druing 2013²017.The results of the determination of serotypes of isolated strains by glass agglutination showed that the dominant serotype of Waterfowl Salmonella was Salmonella typhimurium in Guangdong?with the rate of 92.02%?.Using the pulsed field gel electrophoresis?PFGE?to carry out the molecular typing of isolated bacteria,there were the similarity between the strains was in 54.1%¹00%,62 types of PFGE-Xba?band which were divided into 9 clusters of A^I and 11 single genotypes,including 32 types of PFGE-Xba?bands were the unique bands of each region and each year,the 30 types of PFGE-Xba?bands were distributed across regions and years.These results showed that strain molecular typing analysis has epidemiological significance in Guangdong,PFGE-Xba?type was diversified that 11 kinds of PFGE-Xba?type were concentrated in the area and year of small rangeand 32 kinds of PFGE-Xba?type were scattered in"epidemic out-break"cross-zone and cross-time cross distribution.The PFGE-Xba?band patterns of isolates from different serotypes were quite different and the same type of PFGE-Xba?isolates from the same serotype had the same pattern or clustering.The study had measured the sensitivity of Salmonella isolates from 188 waterfowl sources to 17 common antimicrobial agents by drug sensitive paper agar method,and the results showed that the strains were most resistant to beta lactam and amido alcohols with the drug resistance rate was 69.15%⁸5.11%.Amikacin was most sensitive drug of aminog-lycoside with the resistance rate was only 8.51%.The 87.23%strains were multidrug-resistant to 17 kinds of antibiotics,of which the proportion of AMP-CAZ-GEN-FFC-TET containing drug resistance was up to 51.6%.These results showed that the prevalence trend of penicillins,cephalosporins,aminoglycosides,amidoalcohols and sulfonamides multidrug-resistant strains was prevalent in Guangdong.PCR method was used to investigate the resistance genes of 188 strains of Salmonella isolated from waterfowl to beta lactam,quinolones,amido alcohols,aminoglycosides,sulfo-namides and tetracyclines,and to analyze the relationship between drug-resistant phenotype and drug-resistant genotypes,drug-resistant phenotype and molecular typing.A total of 20resistance genes were detected in 25 resistance genes PCR.Each strain contained at least 3resistance genes,58.51%strains had 10 or more resistance genes,3 strains contained 18resistance genes,the highest detection rate was aadA1gene?with the resistance rate about96.69%?.The results of correlation analysis of resistance phenotype and resistant genotypes showed that 12 resistance genes bla_CTX-M,bla_TEM,bla_oxA,aacC2,APH?3'?-1,AAC?3?-lV,aadA1,qnrS,qnrA,clmA,floR,tetA,sul?and Salmonella resistant strains had significant or very significant relationship,and there was no significant correlation between the drug-resistant phenotype and the PFGE molecular typing.In a word,the study was clear summary of different clinical manifestations of Salmone-llosis in waterfowl,so as to provide reference for clinical diagnosis of Salmonellosis in wate-rfowl.It was clear that the dominant serotype of Salmonella was Salmonella typhimurium and its molecular epidemiology and there were serious drug resistance and multidrug resist-ance genes in Guangdong.What was more,it preliminarily expounded the correlation bet-ween the main biological characteristics of Waterfowl Salmonella,which provides references for further research and clinical prevention and control of Salmonellosis in waterfowl.