Clinical and Microbiological Characteristics of Hospital-Acquired Methicillin-Resistant Staphylococcus aureus Bacteremia Caused by Community-Associated PVL-Negative Strain

Background ST72-SCCmecIV, a community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain in Korea, originated in the community and has been spreading in the healthcare settings. Herein, we describe the clinical and microbiological characteristics of patients with hospital-acquired MRSA bacteremia (MRSAB) caused by community-associated strains. Methods We analyzed hospital-acquired MRSAB cases caused by ST72-SCCmecIV using a prospective cohort of patients with SAB at in a tertiary hospital in Korea from July 2008 to December 2018. We compared the clinical and microbiological characteristics of ST72-SCCmecIV with ST5-SCCmecII, a representative hospital-associated genotype strain. Results Of the 1782 S. aureus bacteremia (SAB) cases, 628 (35.2%) were hospital-acquired MRSAB. Of the 628 isolates, 431 (68.6%) were ST5-SCCmecII and 152 (24.2%) were ST72-SCCmecIV. Patients with ST72-SCCmecIV were younger than those with ST5-SCCmecII and less likely to have a history of recent surgery, antibiotic treatment, nasal MRSA colonization, and central venous catheter placement. Compared with ST5-SCCmecII, ST72-SCCmecIV isolates were more likely to have vancomycin MICs ≤ 1.0 mg/L (P < 0.001). Osteoarticular infection as site of infection [7.2% (11/152) vs. 1.4% (6/431)] was more common in patients with ST72-SCCmecIV. There were no significant differences in the rate of recurrence (≤ 90 days), persistent bacteremia (≥ 7 days), and 30- and 90-day mortality rates between the two groups. Conclusions Osteoarticular infections were more prevalent in ST72-SCCmecIV MRSAB. Mortality rates between the ST72-SCCmecIV and ST5-SCCmecII groups were not significantly different.