| Haemophilus parasuis is caused by HPS which a bacterial infectious disease characterized by multiple fibrinous serositis and arthritis in pigs which also known as Glasser's disease exists in major pig-rearing countries,and the epidemic is on the rise and the hazards are getting worse.The application of antimicrobial agents and inactivated vaccines is the main measure to prevent and control HPS infection.Since HPS has multiple serotypes and has obvious local characteristics,the cross-protection among different serotypes is low,and the strict relationship between serotypes and virulence has not been confirmed.Compared with serotyping,an important advantage of genotyping is the ability to type all isolated strains,which is of practical significance for distinguishing between inhabited avirulent strains and pathogenic strains and in promoting the development of vaccines.The susceptibility of antibiotics to HPS isolates in different countries,different regions,and at different times is different,thus affecting the choice of drugs.In this study,44 strains of HPS isolated and identified in Anhui Province from 2008 to 2017 were first identified by serotype analysis using PCR technology;secondly,the MLST method was used to genotype the isolates.The final application of dilution method to determine the minimum inhibitory concentration(MIC)of drugs against isolates.The aim of this study was to understand the distribution characteristics of HPS serotypes in Anhui Province,to evaluate the genetic background of HPS epidemic in Anhui herds,and to master the sensitivity of HPS Anhui isolates to drugs,so as to provide scientific basis and technical support for the effective prevention and control of HPS infection in Anhui Province.The results showed that 44 strains of HPS isolates in Anhui belonged to 7 serotypes(4,13,5 or 12,1,7,and 14),and serum types 4 and 13 were dominant serotypes,each accounted for 40.91%;from 2008 to 2013 There were 2 serotypes(4,13),accounting for 55.5% and 45.5% respectively,and there were 7 serotypes(13,4,5 or 12,1,1,7 and 14)from 2014 to 2017,which accounted for 36.4% and 27.3 %,13.64%,9.09%,9.90%%,4.55% respectively.The segregation rates of serum type 4 in lung,spleen,and brain were 41.18%,75.0%,and 50%,respectively,while the segregation rates of serum type 13 in lung,joint,and brain were 44.12%,66.67%,and 50%,respectively.The 44 HPS Anhui strains were divided into 9 ST types.In addition to ST241,another 8 were new ST types,ST267 and ST268 were dominant genotypes,each accounted for 40.91%;from 2008 to 2013 there were 2 ST types(ST267).(ST268),which accounted for 55.5% and 45.5%,respectively,and there were 9 ST-types(ST268,ST267,ST269,ST241,ST270,ST271,ST272,ST273,and ST274)from 2014 to 2017,accounting for 36.4% and 27.3% respectively.9.09%,4.55%,4.55%,4.55%,4.55%,4.55%,4.55%;3 to 7 alleles per locus in site polymorphism analysis,3 polymorphic loci(g3pd)up to 37(infB);BURST analysis divided into 2 clone groups(Clonalco,CC)and 7 individual ST types,CC241(ST241,ST254,ST94)and CC268(ST268,ST176)included In regional and other countries,ST type;UPGMA Tree analysis;dominant ST type is in the same evolutionary branch as other ST type(ST268,ST272,ST274 are in the same branch,ST267,ST241 are in the same branch),and there are 3 all contain virulent serum Type(4,5 or 12,13,14)branches.The susceptibility rates of 44 strains of HPS isolates from Anhui Province to gentamicin and penicillin were 100% and 93.2%,respectively.There were 34 resistant patterns that 86.4% of isolates tolerated 2 kinds and more than 2 kinds of drugs;The tolerance of the 11 isolates to the 11 isolates was gradually increased from 2008 to 2017.The drug resistant rates of dominant serotype and ST strains were both 88.9% and 75%,there was no significant difference between them(?2=1.072,P=0.3>0.05).The results showed that the prevalent HPS strains of serotypes and ST types have increased in Anhui Province from 2008 to 2017.The predominant serotypes were type 4 and type 13 and the dominant ST type was ST267 and ST268 which are the main pathogenic bacteria of Glaser's disease in Anhui Province.HPS in Anhui Province has high genetic heterogeneity.The main epidemic strains are related to strains in other regions of China and other countries.The appearance of some new ST types is related to the variation of epidemic strains.ST type There is a certain correlation with virulence serotypes.The resistance rate of HPS in Anhui is on the rise,and the phenomenon of multiple drug resistance is serious.Gentamicin and penicillin are currently the preferred drugs for clinical prevention and treatment of Glaser's disease.There is no obvious correlation between HPS resistance and its serotype and ST type. |
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