Investigation of Virulence Genes and Resistance Genes in a Group of Staphylococcus aureus Isolated in Yuhang, China.

BACKGROUND

To investigate the distribution of virulence genes and resistance genes in a group of Staphylococcus aureus (S. aureus).

METHODS

From February 2013 to April 2014, a total of 39 strains of S. aureus were collected at Hangzhou Yuhang Hospital of Traditional Chinese Medicine, China. Drug sensitivity to 16 kinds of antimicrobial agents was performed by E-test method. A total of 94 virulence genes and 11 resistance genes, including qacA and bsa, were examined by PCR. All virulence and resistance genes were used as molecular markers to perform sample cluster analysis (UPGMA).

RESULTS

At least one gene in every class of virulence genes were positive in strains of S. aureus: adherence, exoenzyme, host immune evasion, and toxin. Eleven virulence genes encoding adherence were positive: clfA, clfB, ebpS, fnbA, icaA, isdA, isdB, isdC, sdrC, sdrD, sdrE; 5 virulence genes encoding exoenzyme were positive: hysA, lip, splB, edinB, nuc; 2 virulence genes encoding host immune evasion were positive: cap5, cap8; 55 kinds of virulence genes encoding toxin were positive: hla, hlb, hlg-2, psm-mec, pvl, sea, seb, sec, sed, see, seg, sei, sek, sel, sem, sen, seo, seq, tst, set1, set2, set3, set4, set5, set6, set7, set8, set9, set10, set11, set12, set13, set14, set15, set16, set17, set18, set19, set20, set21, set22, set24, set25, set26, set30 , set31, set32, set33, set34, set35, set36, set38, set39, set40, lukE. In addition, 39 strains of S. aureus were 100.0% susceptible to quinupristin/dalfopristin, rifampin, vancomycin, tigecycline, and had some resistance rates to 12 other kinds of antimicrobial agents. Six resistance genes were positive: mecA (53.8%), aac6'/aph2" (33.3%), aph3'-III (12.8%), ant4'/ant44" (23.1%), qacA (30.8%), bsa (12.8%). Sample cluster analysis suggested that this group of S. aureus were divided into cluster A and B, and presented a clearly aggregation.

CONCLUSIONS

A great number of virulence genes were positive in this group of S. aureus, contributing to colonization and survival in the host, evading the host immune system, delivering toxins to the host, and promoting pathogenicities. This group of S. aureus also had high resistance, carried some kinds of resistance genes, and had clustering. The implementation of disinfection measures should be strengthened to prevent the occurrence of nosocomial infection.