Epidemiological investigation of community-acquired Staphylococcus aureus infection

The current study aimed to reveal the pathogenic and spreading mechanisms of community-acquired Staphylococcus aureus (CA-SA) by analyzing its prevalence, drug resistance, virulence, and pathogenic factors. Historical information regarding CA skin and soft tissue infections were collected and disease characteristics were analyzed. Isolated CA-SA strains were subjected to antibiotic sensitivity tests using the agar dilution method, Staphylococcus cassette chromosome mec (SCCmec) tests, multilocus sequence typing (MLST), and staphylococcal protein A (SPA) and toxin gene screening. A total of 55 skin and soft tissue infections were investigated, and 12 strains of SA bacteria were isolated, which were all CA methicillin-susceptible SA (CA-MSSA). The antibiotic sensitivity tests showed that CA-MSSA was susceptible to all antibacterials with the exception of high resistance to erythromycin, clindamycin, tetracycline, gentamicin, and levofloxacin (ranging from 8.3 to 50%). The toxin detection results showed that the Panton-Valentine leukocidin (PVL) positive rate in CA-MSSA was 33.3%, the enterotoxin positive rate was 25%, and the toxic shock syndrome toxin-1 (TSSL) positive rate was 8.3%. No Staphylococcus enterotoxin H or Staphylococcus exfoliati was detected. MLST and SPA typing showed that the clones of CA-MSSA included ST5-t002 (2 strains), ST22-t309 (2 strains), ST398-t034, ST15-t5864, ST7-t091, ST25-t078, ST30-t318, ST121-t1425, ST800-t1425, and ST630-t377. No methicillin-resistant SA (MRSA) strains were detected in this study. CA-MSSA strains have high drug susceptibility and diverse genetic backgrounds. The coexistence of multiple toxins may provide a survival advantage in community dissemination for CA-MSSA.