Comparison of Antibiotic Resistance Profiles Between Healthcare-Associated (HA) and Community-Associated (CA) Methicillin-Resistant Staphylococcus aureus = Comparison of Antibiotic Resistance Profiles Between Healthcare-Associated (HA) and Community-Associated (CA) Methicillin-Resistant Staphylococcus aureus

다국어 초록 (Multilingual Abstract)

Introduction: Staphylococcus aureus causes a wide spectrum of clinical syndromes, ranging from skin infections to life-threatening bacteremia. The major community-associated MRSA (CA-MRSA) clone in Korea, ST72-SCCmecVI, has been spreading in both community and healthcare setting, raising serious public health concerns. In this investigation, potential genotype-specific susceptibility profiles to clinically important antibiotics were assessed using ST72-SCCmecIV and ST5-SCCmecII MRSA strains.
Methods: Using a total 76 MRSA strains (41 HA-MRSA and 35 CA-MRSA strains), we determined: i) genotypes such as MLST, spa, agr, SCCmec types; ii) in vitro susceptibilities to ten different antibiotics (ampicillin, chloramphenicol, clindamycin, erythromycin, cefoxitin, gentamicin, rifampin, sulfamethoxazole-trimethoprim, Quinupristin-dalfopristin, tetracycline) using disk diffusion or microdilution methods according to CLSI guideline.
Results: All the ST5 HA-MRSA strains were SCCmecII, while all the ST72 CA-MRSA strains were SCCmecIV. 27 out of 41 HA-MRSA strains were agr type II and 34/35 CA-MRSA strains were agr type I, respectively. Antimicrobial susceptibility analyses revealed that ST5 HA-MRSA strains tend to have higher levels of resistance to 5 antibiotics (chloramphenicol, erythromycin, gentamicin, rifampin, tetracycline) versus ST72 CA-MRSA strains. In addition, ST5 HA-MRSA strains appeared to have higher rates of multidrug-resistance (MDR) compared with those of ST72 CA-MRSA strains.
Conclusion: ST5 HA-MRSA-SCCmecII strains have been associated with higher virulence compared with ST72 CA-MRSA- SCCmecIV strains in Korea. In the current investigation, our results indicate that, in addition to the enhanced virulence, ST5 HA-MRSA-SCCmecII strains have increased resistance to clinically important multiple antibiotics versus the CA-MRSA strains.