Molecular characteristics and virulence genes distribution of community-acquired methicillin-resistant Staphylococcus aureus in skin and soft tissue infection in Quzhou area / 中华检验医学杂志

ABSTRACT

Objective:To investigate the molecular characteristics, drug resistance rate and virulence genes harboring status of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) associated with skin and soft tissue infections (SSTIs), and provide epidemiological basis for clinical antibiotic usage and infection prevention and control. Methods:The Staphylococcus aureus associated with SSTIs in Quzhou People′s Hospital from 2014 to 2018 were retrospectively analyzed. A total of 72 CA-MRSA isolates were screened, and molecular typing was performed by multilocus sequence typing (MLST). K-B method and micro broth dilution method were used to analyze the antibiotic susceptibilities of those strains. The virulence genes screened including fibronectin binding protein genes (fnbA, fnbB),hemolysin genes (hla, hlb), enterotoxin genes (sec, seh) and leukocidin gene (PVL) were detected by polymerase chain reaction (PCR).Statistical analysis of differences between drug resistance rates and virulence genes carrier rates between ST59 and non-ST59 groups used were Chi-square test or Fisher exact test. Results:ST59 type was the main epidemic clone in skin and soft tissue infection CA-MRSA in Quzhou area with account for 55.56% (40/72). All isolates had higher resistance rates to erythromycin (90.28%, 65/72), clindamycin (68.06%, 49/72) and tetracycline (41.67%, 30/72). The nitrofurantoin, daptomycin and linezolid were all sensitive. The resistance rate to clindamycin of sequence type 59 (ST59) was (85.00%, 34/40). The resistance rate of ST59 to clindamycin was significantly higher than that of other clone types (χ 2=11.886, P<0.01). There was no significant difference in the resistance rates of other antibiotics. All 72 isolates exhibited carriage of virulence genes as follows, hla (97.22%, 70/72) , hlb (33.33%, 24/72) , fnbA (50.00%, 36/72) , fnbB (48.61%, 35/72) , PVL (63.89%, 46/72) , sec (4.17%, 3/72) , seh (4.17%, 3/72) . The carrier rate of PVL gene in ST59 type was (77.50%, 31/40). ST59 showed higher rates of PVL genes compared with other clone types (χ 2=7.227, P<0.01). Conclusions:The main clone of CA-MRSA associated with SSTIs in Quzhou was ST59, which was similar to other parts of the Country. The carrying rate of PVL gene of ST59 isolate was significantly higher than that of other isolates. CA-MRSA associated with SSTIs has a high resistance rate to erythromycin and clindamycin, which should not be used as the first choice in treatment.