In Vitro Activity of OPT-80 against Clostridium difficile

Abstract

Clostridium difficile remains the major cause of nosocomial diarrhea. Reports on impaired susceptibility of C. difficile to metronidazole and vancomycin and frequent relapses of patients after therapy necessitate the search for new substances. With this study, the activity of OPT-80, a new macrocycle, against 207 C. difficile strains and against other obligately anaerobic bacteria was tested. OPT-80 showed high in vitro activity against all C. difficile strains tested.

Killing kinetics of fidaxomicin and its major metabolite, OP-1118, against Clostridium difficile

“…Fidaxomicin (formerly OPT-80 and PAR-101) is a novel, narrow-spectrum antibiotic in development for the treatment of C. difficile infection (Ackermann et al, 2004;Credito & Appelbaum, 2004;Finegold et al, 2004). The putative target for fidaxomicin is the RNA polymerase (Talpaert et al, 1975).…”

“…The narrow antimicrobial spectrum of activity of fidaxomicin has been well established by several studies; however, there are no data on the killing kinetics of the compound and its major metabolite (Ackermann et al, 2004;Credito & Appelbaum, 2004;Finegold et al, 2004). This study investigated the killing rate of both fidaxomicin and OP-1118 in comparison with vancomycin in wild-type hypervirulent strains, as well as in laboratory-derived strains with reduced susceptibility to fidaxomicin.…”

Clostridium difficile infection: management strategies for a difficult disease

“…In vitro studies showed that fidaxomicin was more active than vancomycin against C. difficile [Ackermann et al 2004;Finegold et al 2004;Karlowsky et al 2008].…”

Safety and efficacy of fidaxomicin in the treatment of Clostridium difficile-associated diarrhea

“…The molecular structure of fidaxomicin is shown in Figure 1. In vitro, fidaxomicin is bacteriocidal against many species of Clostridia and all types of C. difficile compared with vancomycin, which is bacteriostatic [Ackermann et al 2004;Credito and Appelbaum, 2004;Finegold et al 2004;Karlowsky et al 2008;Hecht et al 2007]. In vitro, fidaxomicin kills organisms more rapidly with a prolonged postantibiotic effect (5.5-10 h) compared with vancomycin (0-1.5 h) Biedenbach et al 2010].…”

“…[Louie et al 2011]. The Minimum Inhibitory Concentration required to inhibit the growth of 90% of organisms (MIC 90 ) of fidaxomicin against C. difficile ranges between 0.0078 and 0.25 µg/ml [Ackermann et al 2004;Credito and Appelbaum, 2004;Finegold et al 2004]. Fidaxomicin is poorly active against gramnegative organisms, Bacteroides spp.…”