Rifampin-Based Combination Therapy is Active in Foreign-Body Osteomyelitis after Prior Rifampin Monotherapy.

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Rifampin-Based Combination Therapy is Active in Foreign-Body Osteomyelitis after Prior Rifampin Monotherapy.

Antimicrob Agents Chemother. 2016 Nov 14;:

Authors: Brinkman CL, Schmidt-Malan SM, Mandrekar JN, Patel R

Abstract
Staphylococcal prosthetic joint infections (PJIs) are associated with biofilm formation, making them difficult to treat; if managed with débridement and implant retention, rifampin-based therapy is usually employed. Rifampin resistance potentially challenges PJI treatment. In investigating the effects of rifampin monotherapy on methicillin-resistant Staphylococcus aureus (MRSA) foreign body osteomyelitis in rats, we previously demonstrated that rifampin resistance was selected but that it disappeared 14 days following rifampin monotherapy (1) and that rifampin resistance occurred less frequently following two rounds than one round of rifampin monotherapy (2). Herein, we compared rifampin monotherapy followed by rifampin/vancomycin combination therapy with rifampin/vancomycin combination therapy alone in experimental MRSA foreign body osteomyelitis. Animals treated with rifampin monotherapy followed by rifampin/vancomycin combination therapy had decreased bacterial quantities 14 days following treatment completion (p=0.034) compared with animals treated with combination therapy alone. Additionally, some isolates recovered from animals treated with combination therapy alone, although still susceptible to rifampin, had higher minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration (MBIC) and minimum biofilm bactericidal concentration (MBBC) values compared to the inoculating strain. This suggests that rifampin may remain a feasible treatment option in foreign body-associated orthopedic infections following selection of rifampin resistance.

PMID: 27855064 [PubMed - as supplied by publisher]