Species-specific Markers Of S.aureus In Animals And Human

Objective:Master the drug resistance and toxin gene prevalence of different animal sources and human Staphylococcus aureus(S.aureus).Compare the differences in molecular type and characteristics between different source strains to reveal different sources of S.aureus specific phenotypes and molecular markers.The study provides an important theoretical basis for predicting the risk of livestock-associated methicillin-resistant S.aureus cross-species transmission,in order to effectively control and suppress the transmission of brake-related S.aureus to the population.Method:A cross-sectional study was conducted in four cities(Shenzhen,Foshan,Dongguan and Jiangmen),which nasal swabs samples were collected.All S.aureus strains were tested for antibiotic susceptibility.PCR amplification techniques were used to detect resistance genes(erm(A)/erm(C),linA,etc),superantigen toxin gene(toxic shock syndrome toxin gene tst1 and enterotoxin genes sea,seb,sec,etc),immune escape cluster(IEC)gene(hlb,scn,chp,sak,sea,sep),hemolytic toxin gene(hla,hlb,hld),leukocyte toxin gene pvl,adhesion genes(bbp,clfA,cna,etc);molecular pattern of S.aureus was obtained by multi-site sequence typing(MLST)experiment.Comparing the rates of each group of samples by?~2 test or Fisher exact test and logistic regression.Correspondence between clonal type and phenotypic-molecular characteristics in S.aureus from different sources was revealed by corresponding analysis.When studying the influencing factors of S.aureus(animal source,human source),the random forest method was used to rank the influencing factors,and then the CART statistical method and logistic regression were used to reveal the high-order interaction between the influencing factors.CC9 S.aureus in animals is defined as animal-derived S.aureus,and non-CC9 S.aureus from human beings is defined as human-derived S.aureus.Results:1.Detection rate and molecular type:the detection rate of S.aureus was 16.6%,MRSA was 5.3%,and the main clonal type were CC188(30strains),CC7(28 strains),CC59(27 strains),CC6(25 strains);the detection rate of S.aureus in the animals was 7.6%,the MRSA was 5.1%,and the main clonal type was CC9.2.Characteristics of animal and human phenotype and molecular characteristics of S.aureus:(1)among the drug resistance,the resistance rates of animal strains was higher than those of human strains(clindamycin,tetracycline,erythromycin,trimethoprim-sulfamethoxazole,gentamicin,etc);(2)Among the drug resistance genes,the genes positive rates of animal strains were higher than that of human strains(tet(M),aacA-aphD,erm(C),msra,etc);(3)Among the IEC genes(scn?chp and sep),enterotoxin genes(sea?sek and sep),adhesion genes(bbp?clfA and spa)and hemolysin gene(hla?hlb and hld),the positive rates of them in animal strains were lower than those in human strains.3.Correspondence analysis between clonal type and phenotype-molecular characteristics of S.aureus in animal and human sources suggests:animal-derived strains are associated with XDR,while human strains are primarily associated with non-MDR;human strains and animal strains carried fewer enterotoxin genes,among which human CC1strain was associated with carrying two enterotoxin genes,human CC6/CC7/CC59/CC188 strain was associated with carrying 0-1enterotoxin gene,and animal strain was associated with carrying one enterotoxin gene;human CC7 strain was associated with carrying two adhesion genes,human CC1/CC5/CC15/CC59/CC188 strain was associated with carrying one adhesion gene,and animal-derived strain was associated with deletion of adhesion genes;human CC15 strain is associated with carrying 4-5 IEC genes,human CC1/CC6/CC7/CC188strain is associated with carrying 3 IEC genes,and animal-derived strain is associated with carrying 1-2 IEC genes;human strain CC1/CC59/CC188/CC6/CC7 was associated with carrying three hemolysin genes,human strain CC5 was associated with carrying two hemolysin genes,and animal strain was associated with carrying two hemolysin genes.4.Random forests rank the importance of influencing factors to reveal the source of strains:in drug resistance phenotype,the importance of resistance to sulfamethoxazole and tetracycline is relatively high;in drug resistance genes,gentamicin resistance gene(aacA-aphD)and tetracycline resistance gene(tet(M)and tet(K))have higher index ranking;in IEC genes,scn and sep genes are of the most importance;in enterotoxin gene,seh,sem and sek genes are the most important genes;in hemolytic toxin gene:hld gene is the most important;in adhesion factor related genes,spa is the most important gene.5.CART and logistic regression to explore the potential interaction of influencing factors of strain source:the simultaneous drug resistance rate of sulfamethoxazole-tetracycline(OR=508.08)and the simultaneous carrying rate of(aacA-aphD)-tet(M)(OR=1332.00)in the animal-derived S.aureus was significantly higher than that of the human strain;the proportion of IEC combination scn(-)-sep(-)-chp(+)(OR=1.88),enterotoxin combination seh(+)-sek(-)(OR=87.50)and non-hld gene(OR=20.96)of animal-derived S.aureus was significantly higher than that of human-derived strains.Conclusion:1.Differences in phenotypic and molecular characteristics between human and animal-derived S.aureus suggest that animal-derived strains have higher resistance rates than human strains;animal-derived strains carry more resistant genes than human strains;however,the carrying rate of the IEC gene,enterotoxin gene,adhesion factor gene and hemolytic toxin gene of human strains is generally higher than that of animal strains.2.Correspondence analysis revealed the association between different clonal type and phenotypic-molecular characteristics:animal-derived S.aureus was associated with XDR,while human-derived S.aureus was mainly associated with non-MDR,suggesting that the drug resistance of animal-related strains cannot be ignored;human-derived strain is closely related to carrying 4-5 IEC genes and 1-2 adhesion factor genes,while animal-derived strains show widespread loss of these toxin genes;hla,hlb and hld hemolysin genes are ubiquitous in human and animal strain.3.CART combined with logistic regression to explore the role of different combinations of phenotype-molecular features in human and animal strains.the simultaneous drug resistance rate of sulfamethoxazole-tetracycline and the simultaneous carrying rate of(aacA-aphD)-tet(M)in the animal-derived S.aureus was significantly higher than that of the human strain;the proportion of IEC combination scn(-)-sep(-)-chp(+),enterotoxin combination seh(+)-sek(-)and non-hld gene of animal-derived S.aureus was significantly higher than that of human-derived strains.