Drug resistance and virulence genes in MRSA strains isolated from children with acute hematogenous osteomyelitis

OBJECTIVE To explore the drug resistance and virulence genes in methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from children with acute hematogenous osteomyelitis. METHODS A total of 102 acute hematogenous osteomyelitis children with S.aureus infection who were treated in Quzhou People's Hospital from Feb 2017 to Dec 2019 were recruited as the research subjects and were divided into the MRSA group with 43 cases and the methicillin-sensitive S.aureus (MSSA) group with 59 cases according to the result of methicillin resistance testing for the S.aureus strains. The positive rates of virulence genes were compared between the two groups, and the relationship between the virulence genes and the methicillin resistance in S.aureus strains, severity of disease and prognosis was observed. RESULTS Among the children with S.aureus infection, the isolation rate of MSSA was higher than that of the MRSA. The drug resistance rates of the MRSA strains to oxacillin, cefoxitin, cefazolin and cefuroxime were significantly higher than those of the MSSA strains(P<0.05). The positive test of Psm-mec was a risk factor for the methicillin resistance in S.aureus strains (P<0.05); the positive rate of Psm-mec was increased with the aggravation of illness condition of the children with acute hematogenous osteomyelitis, while the positive rate of pvl was decreased with the aggravation of illness condition (P<0.05). The positive test of Psm-mec was a risk factor affecting the severity of acute hematogenous osteomyelitis, and pvl was a protective factor (P<0.05). There were no significant differences in the positive rates of sasX, Psm-mec and pvl between the favorable prognosis group and the poor prognosis group. CONCLUSION The acute hematogenous osteomyelitis children with S.aureus infection show high drug resistance rate to methicillin, and the virulence genes are associated with the MRSA and severity of disease.