Molecular Characteristics and Prevalence of Rifampin Resistance in <i>Staphylococcus aureus</i> Isolates from Patients with Bacteremia in South Korea

• Main Authors: Yong Kyun Kim (Author), Yewon Eom (Author), Eunsil Kim (Author), Euijin Chang (Author), Seongman Bae (Author), Jiwon Jung (Author), Min Jae Kim (Author), Yong Pil Chong (Author), Sung-Han Kim (Author), Sang-Ho Choi (Author), Sang-Oh Lee (Author), Yang Soo Kim (Author)
• Format: Book
• Published: MDPI AG, 2023-10-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/antibiotics12101511; 2079-6382
• Keywords: rifampin resistance; <i>Staphylococcus aureus</i>; bacteremia; molecular typing; <i>rpoB</i> gene; mutation; Therapeutics. Pharmacology; RM1-950
• Source: Antibiotics, Vol 12, Iss 10, p 1511 (2023)

Rifampin resistance (RIF-R) in <i>Staphylococcus aureus</i> (<i>S. aureus</i>) with <i>rpoB</i> mutations as one of its resistance mechanisms has raised concern about clinical treatment and infection prevention strategies. Data on the prevalence and molecular epidemiology of RIF-R <i>S. aureus</i> blood isolates in South Korea are scarce. We used broth microdilution to investigate RIF-R prevalence and analyzed the <i>rpoB</i> gene mutation in 1615 <i>S. aureus</i> blood isolates (772 methicillin-susceptible and 843 methicillin-resistant <i>S. aureus</i> (MRSA)) from patients with bacteremia, between 2008 and 2017. RIF-R prevalence and antimicrobial susceptibility were determined. Multilocus sequence typing was used to characterize the isolate's molecular epidemiology; Staphylococcus protein A (s<i>pa</i>)<i>,</i> staphylococcal cassette chromosome <i>mec</i> (SCC<i>mec</i>), and <i>rpoB</i> gene mutations were detected by PCR. Among 52 RIF-R MRSA isolates out of 57 RIF-R <i>S. aureus</i> blood isolates (57/1615, 0.4%; 5 methicillin-susceptible and 52 MRSA), ST5 (44/52, 84.6%), SCC<i>mec</i> IIb (40/52, 76.9%), and <i>spa</i> t2460 (27/52, 51.9%) were predominant. <i>rpoB</i> gene mutations with amino acid substitutions showed that A477D (17/48, 35.4%) frequently conferred high-level RIF resistance (MIC > 128 mg/L), followed by H481Y (4/48, 8.3%). RIF-R <i>S. aureus</i> blood isolates in South Korea have unique molecular characteristics and are closely associated with <i>rpoB</i> gene mutations. RIF-R surveillance through <i>S. aureus</i>-blood isolate epidemiology could enable effective therapeutic management.