Drug Resistance and Virulence Factors of Staphylococcus Aureus Isolated from Patients with Infective Endocarditis

HAN Jing; LIU Jing; YANG Zijian

doi:10.3969/j.issn.1004-437X.2025.06.018

Abstract：Objective To analyze the drug resistance and virulence factors of Staphylococcus aureus(SA)isolated from patients with infective endocarditis(IEC).Methods A total of 92 strains of SA isolated from different samples of patients with IEC admitted to Medical Laboratory Center of Anyang People's Hospital from January 2021 to January 2023 were collected,and strain identification and drug sensitivity test were performed by instrument method and paper disk method.Multiple polymerase chain reaction(PCR)was used to detect virulence factors genes[fibrinogen agglutinin A(clfA),hemolysin(hld),fibrinogen agglutinin B(clfB),enterotoxin B(seb),enterotoxin A(sea),leukocidin(pvl),toxic shock syndrome toxin(tsst-Ⅰ)].According to drug resistance,they were divided into methicillin-resistant staphylococcus aureus(MRSA)group and methicillin-sensitive staphylococcus aureus(MSSA)group,and the drug resistance and virulence factors of SA were analyzed.Results The sensitivity rates of 92 SA strains to linezolid,tigacycline,vancomycin and quinupristin/dalfopristin were all 100.00％,and the sensitivity rates to moxifloxacin,rifampicin,gentamicin,levofloxacin,tetracycline,ciprofloxacin,compound sulfamethoxazole and oxacillin were higher than 72.00％,and the sensitivity rates to clindamycin and erythromycin were lower than 53.00％,and the sensitivity rate to penicillin was only 14.13％.Among 92 SA strains,there were 27 strains of MRSA(27/92,29.35％,MRSA group)and 65 strains of MSSA(65/92,70.65％,MSSA group).The sensitivity rates to tetracycline,oxacillin,clindamycin,erythromycin and penicillin in MSSA group were higher than those in MRSA group(P＜0.05).All 7 virulence factors genes in 92 strains of SA could be detected,and the positive rates from high to low were clfA(90.22％),hld(85.87％),clfB(80.43％),seb(67.39％),sea(33.70％),pvl(13.04％)and tsst-Ⅰ(6.65％).The positive rate of virulence factor clfB(66.67％)in MRSA group was lower than that in MSSA group(86.15％)while the positive rates of seb(96.30％)and tsst-Ⅰ(22.22％)were higher than those in MSSA group(55.38％,0)(P＜0.05).The proportion of carrying 2 virulence factors in MRSA group(3.70％)was lower than that in MSSA group(20.00％),while the proportion of carrying 5 virulence factors(29.63％)was higher than that in MSSA group(10.77％)(P＜0.05).Conclusion The SA isolated from samples of patients with IEC is highly sensitive to linezolid,tigacycline,vancomycin and quinupristin/dalfopristin,but the sensitivity rate in MRSA group is generally lower than that in MSSA group.The mechanism of drug resistance may be related to the carrying rates of virulence factors clfB,seb and tsst-Ⅰ and virulence factor count.