OBJECTIVES: Infections caused by Staphylococcus aureus might be treated with agents whose primary indications are for other infections. Clofazimine, an established anti-mycobacterial drug, could be such a candidate. However, the anti-staphylococcal properties of clofazimine have not been fully described and its mode of action, possibly involving inhibition of both RNA polymerase and a membrane-located target, has not been explored in detail. We have now conducted experiments to address these issues. METHODS: Using established procedures, we examined the activity of clofazimine against a range of clinical isolates of S. aureus and determined whether it was bactericidal, exhibited a post-antibiotic effect (PAE), or interacted synergically with other agents. The potential for emergence of clofazimine-resistant mutants was also examined. Mode of action studies involved macromolecular synthesis assays, cross-screening against rifampicin-resistant mutants, susceptibility of RNA polymerase to clofazimine in vitro and several methods to detect drug-induced membrane damage. RESULTS: Clofazimine demonstrated good anti-staphylococcal activity encompassing MSSA, MRSA and GISA. It was bactericidal and resistant mutants could not be isolated. Clofazimine did not exhibit a PAE and failed to act synergically with other drugs. No evidence for specific inhibition of RNA polymerase was obtained. Clofazimine caused non-specific inhibition of DNA, RNA and protein synthesis, consistent with membrane-damaging activity that was detected in three independent assays for membrane disrupting agents. CONCLUSIONS: Clofazimine is a potent anti-staphylococcal agent. It appears to be a membrane-disrupting agent and does not inhibit RNA polymerase.
OBJECTIVES:Infections caused by Staphylococcus aureus might be treated with agents whose primary indications are for other infections. Clofazimine, an established anti-mycobacterial drug, could be such a candidate. However, the anti-staphylococcal properties of clofazimine have not been fully described and its mode of action, possibly involving inhibition of both RNA polymerase and a membrane-located target, has not been explored in detail. We have now conducted experiments to address these issues. METHODS: Using established procedures, we examined the activity of clofazimine against a range of clinical isolates of S. aureus and determined whether it was bactericidal, exhibited a post-antibiotic effect (PAE), or interacted synergically with other agents. The potential for emergence of clofazimine-resistant mutants was also examined. Mode of action studies involved macromolecular synthesis assays, cross-screening against rifampicin-resistant mutants, susceptibility of RNA polymerase to clofazimine in vitro and several methods to detect drug-induced membrane damage. RESULTS:Clofazimine demonstrated good anti-staphylococcal activity encompassing MSSA, MRSA and GISA. It was bactericidal and resistant mutants could not be isolated. Clofazimine did not exhibit a PAE and failed to act synergically with other drugs. No evidence for specific inhibition of RNA polymerase was obtained. Clofazimine caused non-specific inhibition of DNA, RNA and protein synthesis, consistent with membrane-damaging activity that was detected in three independent assays for membrane disrupting agents. CONCLUSIONS:Clofazimine is a potent anti-staphylococcal agent. It appears to be a membrane-disrupting agent and does not inhibit RNA polymerase.
Authors: Anna C Jacobs; Louis Didone; Jennielle Jobson; Madeline K Sofia; Damian Krysan; Paul M Dunman Journal: Antimicrob Agents Chemother Date: 2012-10-01 Impact factor: 5.191
Authors: Ming Zhang; Claudia Sala; Ruben C Hartkoorn; Neeraj Dhar; Alfonso Mendoza-Losana; Stewart T Cole Journal: Antimicrob Agents Chemother Date: 2012-08-27 Impact factor: 5.191
Authors: Gi S Yoon; Rahul K Keswani; Sudha Sud; Phillip M Rzeczycki; Mikhail D Murashov; Tony A Koehn; Theodore J Standiford; Kathleen A Stringer; Gus R Rosania Journal: Antimicrob Agents Chemother Date: 2016-05-23 Impact factor: 5.191