Antimicrobial susceptibility of Brazilian Clostridium difficile strains determined by agar dilution and disk diffusion

作者：Fraga Edmir Geraldo; Nicodemo Antonio Carlos^*; Mello Sampaio Jorge Luiz

来源：Brazilian Journal of Infectious Diseases, 2016, 20(5): 476-481.

DOI：10.1016/j.bjid.2016.07.004

• Clostridium difficile
• Disk diffusion
• Agar dilution
• Susceptibility testing

Clostridium difficile is a leading cause of diarrhea in hospitalized patients worldwide. While metronidazole and vancomycin are the most prescribed antibiotics for the treatment of this infection, teicoplanin, tigecycline and nitazoxanide are alternatives drugs. Knowledge on the antibiotic susceptibility profiles is a basic step to differentiate recurrence from treatment failure due to antimicrobial resistance. Because C. difficile antimicrobial susceptibility is largely unknown in Brazil, we aimed to determine the profile of C. difficile strains cultivated from stool samples of inpatients with diarrhea and a positive toxin A/B test using both agar dilution and disk diffusion methods. All 50 strains tested were sensitive to metronidazole according to CLSI and EUCAST breakpoints with an MIC90 value of 21,1 mu g/mL. Nitazoxanide and tigecycline were highly active in vitro against these strains with an MIC90 value of 0.125 mu g/mL for both antimicrobials. The MIC90 were 4 mu g/mL and 2 mu g/mL for vancomycin and teicoplanin, respectively. A resistance rate of 8% was observed for moxifloxacin. Disk diffusion can be used as an alternative to screen for moxifloxacin resistance, nitazoxanide, tigecycline and metronidazole susceptibility, but it cannot be used for testing glycopeptides. Our results suggest that C. difficile strains from Sao Paulo city, Brazil, are susceptible to metronidazole and have low MIC90 values for most of the current therapeutic options available in Brazil.

• 出版日期2016-10