Article

In Vitro Antimicrobial Findings for Fusidic Acid Tested Against Contemporary (2008–2009) Gram-Positive Organisms Collected in the United States

JMI Laboratories, North Liberty, Iowa, USA.
Clinical Infectious Diseases (Impact Factor: 8.89). 06/2011; 52 Suppl 7(suppl 7):S477-86. DOI: 10.1093/cid/cir163
Source: PubMed

ABSTRACT

Fusidic acid has a long history of consistent activity against staphylococcal pathogens including methicillin-resistant Staphylococcus aureus (MRSA). Fusidic acid (CEM-102) was susceptibility tested against a surveillance study collection of 12,707 Gram-positive
pathogens (2008–2009) from the United States. Reference broth microdilution method results demonstrated the following MIC50/90 results: S. aureus (.12/.25 μg/mL), coagulase-negative staphylococci (.12/.25 μg/mL), enterococci (4/4 μg/mL), Streptococcus pyogenes (4/8 μg/mL), and viridans group Streptococcus spp. (>8/>8 μg/mL). At a proposed susceptible breakpoint (≤1 μg/mL), fusidic
acid inhibited 99.7% of MRSA strains and 99.3% to 99.9% of multidrug-resistant phenotypes of S. aureus. Furthermore, S. aureus strains nonsusceptible to fusidic acid (.35%) generally had detectable resistance mechanisms (fusA, B, C, and E). Reviews of in vitro susceptibility test development confirm the accuracy and intermethod reproducibility of various fusidic
acid methods. Fusidic acid is a promising oral therapy for staphylococcal skin and skin structure infections in the United
States, where the contemporary S. aureus population remains without significant resistance.

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    • "FA inhibits protein synthesis in bacteria and acts against many pathogens including Staphylococcus aureus, gram-positive anaerobic bacteria, Neisseria spp., and Bordetella pertussis [19]. It is used clinically as a topical application or systemic treatment, particularly in case of bone and joint infections or skin and soft tissue infections [19]. EF-G has five structural domains (DI–DV). "
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    • "Some authors have proposed that isolates with MIC ≤ 1.0 μg/mL are susceptible (S) and those with MIC ≥ 2.0 μg/mL are resistant (R) while others have proposed an MIC ≤ 0.5 μg/mL as the susceptible breakpoint [10] [12]. Most recently Jones et al. compared broth dilution, Etest MIC, and disk diffusion, and they proposed an MIC ≥ 4.0 μg/mL as the interpretive break point for resistance and ≤1.0 μg/mL for susceptibility [13]. For disk diffusion testing, EUCAST has set the 10 μg fusidic acid zone size for resistance at 24 mm, while Skov et al. recently proposed ≤18 mm for resistance and ≥21 mm as susceptible interpretive break points [10] [12]. "
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    • "Fusidic acid offers a potentially valuable systemic treatment option for ABSSSI, including for medically complex patients. It has a broad gram-positive antimicrobial spectrum [10, 21]; oral bioavailability [22]; a long safety history, including in patients receiving prolonged courses of treatment [23, 24] ; and a mechanism of action that is not shared with any other available antibacterial agent [9]. As shown inTable 3, there are some imbalances between the 2 treatment groups. "
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