Effects of sub-inhibitory concentrations of nafcillin, vancomycibipn, ciprofloxacin, and rifampin on biofilm formation of clinical methicillin-resistant <i>Staphylococcus aureus</i>open access
- Authors
- Park, Ki-Ho; Kim, Dokyoung; Jung, Minji; Kim, Dong Youn; Lee, Yu-Mi; Lee, Mi Suk; Hong, Kyung-Wook; Bae, In-Gyu; Hong, Sun In; Cho, Oh-Hyun
- Issue Date
- Apr-2024
- Publisher
- AMER SOC MICROBIOLOGY
- Keywords
- Staphylococcus aureus; biofilm; nafcilllin; vancomycin; ciprofloxacin; rifampin
- Citation
- MICROBIOLOGY SPECTRUM
- Journal Title
- MICROBIOLOGY SPECTRUM
- URI
- https://scholarworks.bwise.kr/sch/handle/2021.sw.sch/26267
- DOI
- 10.1128/spectrum.03412-23
- ISSN
- 2165-0497
- Abstract
- Methicillin-resistant Staphylococcus aureus (MRSA) infections are often difficult to treat because of their biofilm-forming ability and antimicrobial resistance. We investigated the effects of sub-minimal inhibitory concentrations (MICs) of antibiotics on MRSA biofilm formation. Clinical MRSA isolates were grown with sub-MICs (1/256-1/2 x MICs) of nafcillin, vancomycin, ciprofloxacin, and rifampin. The biofilm biomass was measured using crystal violet staining. Of the 107 MRSA isolates tested, 63 (58.9%) belonged to sequence type 5 (ST5), and 44 (41.1%) belonged to ST72. The MIC50/MIC90 values of nafcillin, vancomycin, ciprofloxacin, and rifampin were 256/512, 1/2, 64/512, and 0.008/0.03 mg/L, respectively. The sub-MICs of nafcillin, vancomycin, ciprofloxacin, and rifampin promoted biofilm formation in 75 (70.1%), 49 (45.8%), 89 (83.2%), and 89 (83.2%) isolates, respectively. At sub-MICs of nafcillin, the factors associated with strong biofilm induction were the ST5 strain (P = 0.001) and agr dysfunction (P = 0.005). For the sub-MICs of ciprofloxacin, the associated factors were the ST5 strain (P = 0.002), staphylococcal protein A type t002 strain (P < 0.001), and ciprofloxacin resistance (P < 0.001). Among the sub-MICs of rifampin, only ST5 was associated with strong biofilm induction (P = 0.006). Because the sub-MICs of rifampin were much lower than clinically relevant concentrations, we further tested the capability of biofilm induction in 0.03 - 32 mg/L of rifampin. At these concentrations, rifampin-induced biofilm formation was rare in rifampin-susceptible MRSA [1.0% (1 of 100)] but common in rifampin-resistant MRSA [71.4% (5 of 7), P < 0.001]. Induction of biofilm biomass at sub-MICs of antibiotics is common in clinical MRSA isolates and is differentially affected by the MRSA strain and antibiotic class.
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Collections - College of Medicine > Department of Internal Medicine > 1. Journal Articles
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