Evaluation of in vitro efficacies of ciprofloxacin，cotrimoxazole，and rifampin used alone and in combination against methicillin-resistant Staphylococcus aureus
| Autor: | Yu-Chan Kang, 康玉嬋 |
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| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 We conducted an in vitro time-kill study to evaluate the efficacies of ciprofloxacin, cotrimoxazole, and rifampin used alone and in combination against a randomly chosen clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA), with an attempt to improve the therapeutic outcomes of infections, such as chronic osteomyelitis, in which local antibiotic concentrations are often inadequate. Chronic osteomyelitis caused by MRSA is one of the therapeutically intractable infections, and the suboptimal local antibiotic concentrations in the sequestrum account for the high recurrence rates of osteomyelitis.Currently, intravenous therapy with vancomycin or teicoplanin coupled with surgical debridement is the standard therapy for inpatients with chronic osteomyelitis caused by MRSA. However, the standard of subsequent long-term oral antibiotic treatment of chronic osteomyelitis has not yet been established. With the limited optional antibiotics available, the synergistic effect of combination of the readily widely used drugs in the treatment of chronic osteomyelitis cannot be overemphasized. Combined use of antibiotics additionally hampers the development of antimicrobial resistance. In the time-kill study presented in this paper, ciprofloxacin, cotrimoxazole, and rifampin (each at 1×MIC and 1/2×MIC) were used alone, in two-drug and three-drug combinations, respectively. A starting MRSA inoculum of approximate 10 6 CFU/ml was used in each experiment whose experimental time lasted for 48 hours.Our study demonstrated the excellent inhibitory activities against MRSA by ciprofloxacin plus cotrimoxazole and by ciprofloxacin plus cotrimoxazole and rifampin, respectively, for 48 hours at merely 1×MIC and 1/2×MIC of each drug. Our result also confirms the previous study indicating the inhibitory effects of the combinations of ciprofloxacin plus rifampin and cotrimoxazole plus rifampin against MRSA, when these antibiotics each were used at such a low concentration.The synergistic antimicrobial effects by combined antibiotics each with a subinhibitory concentration suggest the potential for the applicability of combined antibiotics for treatment of osteomyelitis caused by MRSA, because in such circumstances adequate local individual antibiotic concentration is hardly achieved due to compromised tissue perfusion.As aforementioned, the synergistic antibiotic effect can also prevent the inevitable development of antimicrobial resistance in the presence of the subinhibitory concentration of an antibiotic should it be used alone. Theoretically, the synergistic effect of combined antibiotics each with a subinhibitory concentration additionally makes oral antibiotic therapy for osteomyelitis caused by MRSA possible. In conclusion, our in vitro study shows that the combination of ciprofloxacin, cotrimoxazole, and rifampin is synergistically highly active against MRSA. Our study discloses important experimental data, and in view of their potentially beneficial value in applicability, further in vivo and clinical studies are deserved. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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