四川部分地区猪链球菌的分离鉴定及其毒力基因型和耐药性研究

Isolation and identification of Streptococcus suis in some areas of Sichuan Province and study on its virulence genotype and drug resistance

为了解四川地区猪链球菌流行毒株的血清型、毒力基因型及耐药情况,试验采集2021—2022年四川部分地区生猪养殖场死亡猪肺脏组织151份,对疑似猪链球菌的菌株进行分离与鉴定,并对分离到的猪链球菌菌株进行血清型鉴定,对可定型猪链球菌菌株进行毒力因子(sly、mrp、epf)检测和药敏试验。结果表明:151份肺脏组织样品中,共分离鉴定出猪链球菌32株;在分离到的32株猪链球菌菌株中,可定型菌株有24株,分属于8种血清型。其中血清16型有10株,占比31.2%,为优势血清型;血清2型有7株,占比21.9%;血清9型有2株,占比6.3%;血清1型、4型、5型、7型、30型各有1株,均占比3.1%。未定型菌株有8株,占比25.0%。24株可定型菌株共检出5种毒力基因型,分别为sly+mrp-epf-(11/24)、sly+mrp+epf+(1/24)、sly-mrp-epf-(8/24)、sly-mrp+epf+(1/24)、sly+mrp+epf-(3/24),其中优势毒力基因型为sly+mrp-epf-。24株猪链球菌对林可霉素的耐药率最高,为100%;其次是克林霉素和氟苯尼考(均为91.7%);对头孢匹罗的耐药率最低(37.5%)。24株猪链球菌整体耐药情况严重,其中20株菌株表现为多重耐药,占比83.3%;1株菌株为8耐,即对本试验中的8类抗生素均耐药。说明四川地区猪链球菌存在多种血清型,其中16型、2型为主要血清型,sly+mrp-epf-为优势毒力基因型,整体耐药情况严重,且绝大多数菌株属于多重耐药菌株。

In order to understand the serotype,virulence genotype and drug resistance of the epidemic strains of Streptococcus suis in Sichuan Province,in this experiment,151 lung tissue samples from dead pigs in pig farms in some areas of Sichuan Province were collected from 2021 to 2022;the strains suspected of Streptococcus suis were isolated and identified,and the isolated strains of Streptococcus suis were carried out for serotyping identification,and virulence factor(sly,mrp,epf)test and susceptibility test were performed on the typed strains of Streptococcus suis.The results showed that among the 151 lung tissue samples,a total of 32 strains of Streptococcus suis were isolated and identified.Among the 32 isolated strains of Streptococcus suis,24 strains were typed,belonging to 8 serotypes,of which 10 were serotype 16,accounting for 31.2%,being the dominant serotype.There were 7 strains for serotype 2,accounting for 21.9%;2 strains for serotype 9,accounting for 6.3%;one strain each for type 1,4,5,7 and 30,each accounting for 3.1%;there were 8 un-typed strains,accounting for 25.0%.A total of 5 virulence genotypes were detected in 24 typed strains,namely sly+mrp-epf-(11/24),sly+mrp+epf+(1/24),sly-mrp-epf-(8/24),sly-mrp+epf+(1/24),sly+mrp+epf-(3/24);and the dominant virulence genotype was sly+mrp-epf-.24 strains of Streptococcus suis had the highest resistance rate to lincomycin,which was 100%;this was followed by clindamycin and florfenicol(91.7%),and the lowest resistance to cefpirome(37.5%).The overall resistance of 24 strains of Streptococcus suis was serious,of which 20 strains showed multi-drug resistance,accounting for 83.3%;one strain was 8-resistant,that was,resistant to all 8 classes of antibiotics in this test.The results suggested that there were multiple serotypes of Streptococcus suis in Sichuan Province,of which types 16 and 2 were the main serotypes,and sly+mrp-epf-was the dominant virulence genotype;and the overall drug resistance was serious,and most of the strains were multi-drug-resistant.