Antimicrobial activities of trimethoprim/sulfamethoxazole, 5-iodo-2'-deoxyuridine and rifampicin against Staphylococcus aureus.
Trimethoprim/sulfamethoxazole (SXT), alone and in combination with rifampicin (RIF), is a therapeutic option against Staphylococcus aureus, including strains expressing meticillin resistance. However, the antimicrobial activity of SXT is antagonised by thymidine, which can be present in infected and/or inflamed tissues such as the airways of cystic fibrosis (CF) patients. In this study, thymidine concentrations in CF sputa were determined and the antimicrobial activities of SXT, 5-iodo-2'-deoxyuridine (IdUrd) and RIF alone and in combination against S. aureus were analysed. Thymidine concentrations in the sputa of ten different CF patients varied from <100 μg/L to 38845 μg/L. The abolished antimicrobial activity of SXT against 22 S. aureus strains in the presence of thymidine was restored by combination with IdUrd. In contrast, SXT combined with RIF in the presence of thymidine did not show a synergistic effect and, furthermore, allowed the emergence of RIF-resistant bacteria. Adding RIF to the combination of SXT and IdUrd did not improve antimicrobial activity against S. aureus. In conclusion, the combination of SXT and RIF as a therapeutic option against S. aureus infections in chronic inflamed tissues should be judged critically.
Institute of Medical Microbiology and Infection Control, Hospital of Goethe-University, Paul-Ehrlich-Str. 40, 60596 Frankfurt/Main, Germany.
Johannes
J
Zander
Silke
S
Besier
Sebastian
S
Faetke
Stephan H
SH
Saum
Volker
V
Müller
Thomas A
TA
Wichelhaus
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D003550:Cystic Fibrosis / Q000382:microbiology; D004347:Drug Interactions; D006801:Humans; D007065:Idoxuridine / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D012293:Rifampin / Q000494:pharmacology*; D013183:Sputum / Q000737:chemistry / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects*; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D007065:Idoxuridine; D012293:Rifampin