Epidemiology and antibiotic resistance of methicillin-resistant Staphylococcus aureus in Jingzhou

Abstract

Objective To investigate the epidemiology and antibiotic resistance of community-associated and hospital-associated meticillin-resistant Staphylococcus aureus (CA-MRSA and HA-MRSA) in Jingzhou. Methods A total of 159 MRSA isolates were successively collected from patients in Jingzhou Central Hospital during January 2012 and December 2013. The minimum inhibitory concentrations of 16 antimicrobial agents against 159 MRSA isolates were detected. SCCmec types of the strains were detected by multiplex PCR, and the homology of the strains was analyzed using pulsed field gel electrophoresis (PFGE) and cluster analysis of antibiogram. WHONET 5.6 and SPSS 19.0 were used for data analysis. Results Among 159 MRSA strains, 131 were hospital-associated, and 28 were community-associated, which accounted for 82.4% and 17.6%, respectively. There were significant differences in the age of patients, ward distribution, specimen type, length of stay, length of anti-infection treatment, type of infection and underlying diseases between patients with CA-MRSA or HA-MRSA infections (χ2=19.103, 31.372, 59.756, 71.703, 54.153, 59.756 and 54.232, all P<0.01). No vancomycin, linezolid, tigecycline and nitrofurantoin resistant strains were found, but all strains were resistant to penicillin, cefoxitin and oxacillin. HA-MRSA had higher resistance rates to moxifloxacin, levofloxacin, rifampicin, ciprofloxacin and gentamicin than CA-MRSA (χ2=30.179, 27.352, 28.523, 28.523 and 25.987, all P<0.01), but its resistance rates to erythromycin and clindamycin were lower (χ2=13.106 and 11.743, both P<0.01). Among 159 MRSA strains, 12 (7.5%) were of SCCmec typeⅡ, 113 (71.1%) were of SCCmec type Ⅲ, 26 (16.4%) were of SCCmec type Ⅳ, and 8 were of undifferentiated type. The predominant SCCmec types were typeⅣ for CA-MRSA (26/28, 92.9%) and type Ⅲ for HA-MRSA (113/131, 86.3%), respectively. Six PFGE patters were found in 49 HA-MRSA isolates from ICU, and the predominant patters were A1 (24, 49.0%), A2 (9, 18.4%) and B (9, 18.4%). Cluster analysis of antibiogram showed that three groups of HA-MRSA were of high correlations, and they were of PFGE patter A1, A2 and B, respectively. Conclusions HA-MRSA is the predominant MRSA in Jingzhou area, and it is different from CA-MRSA in the age of patients, ward distribution, type of infection and antibiotic resistance. Most HA-MRSA strains are of type SCCmecⅢ, and may cause epidemic outbreak in ICU. Key words: Methicillin-resistant Staphylococcus aureus; Community-acquired infections; Hospital-associated infections