Clostridium difficile Infection: Current and Emerging Therapeutics

Detection and Investigation of Eagle Effect Resistance to Vancomycin in Clostridium difficile With an ATP-Bioluminescence Assay

Vancomycin was bactericidal against Clostridium difficile at eightfold the minimum inhibitory concentration (MIC) using a traditional minimum bactericidal concentration (MBC) assay. However, at higher concentrations up to 64 × MIC, vancomycin displayed a paradoxical “more-drug-kills-less” Eagle effect against C. difficile. To overcome challenges associated with performing the labor-intensive agar-based MBC method under anaerobic growth conditions, we investigated an alternative more convenient ATP-bioluminescence assay to assess the Eagle effect in C. difficile. The commercial BacTiter-Glo^TM assay is a homogenous method to determine bacterial viability based on quantification of bacterial ATP as a marker for metabolic activity. The ATP-bioluminescence assay was advantageous over the traditional MBC-type assay in detecting the Eagle effect because it reduced assay time and was simple to perform; measurement of viability could be performed in less than 10 min outside of the anaerobic chamber. Using this method, we found C. difficile survived clinically relevant, high concentrations of vancomycin (up to 2048 μg/mL). In contrast, C. difficile did not survive high concentrations of metronidazole or fidaxomicin. The Eagle effect was also detected for telavancin, but not for teicoplanin, dalbavancin, oritavancin, or ramoplanin. All four pathogenic strains of C. difficile tested consistently displayed Eagle effect resistance to vancomycin, but not metronidazole or fidaxomicin. These results suggest that Eagle effect resistance to vancomycin in C. difficile could be more prevalent than previously appreciated, with potential clinical implications. The ATP-Bioluminescence assay can thus be used as an alternative to the agar-based MBC assay to characterize the Eagle effect against a variety of antibiotics, at a wide-range of concentrations, with much greater throughput. This may facilitate improved understanding of Eagle effect resistance and promote further research to understand potential clinical relevance.

Clostridium difficile colitis: A clinical review

BACKGROUND

Clostridium difficile colitis is an important cause of morbidity and mortality in the surgical patient. In recent years, Clostridium difficile infections have shown marked increases in frequency, severity, and resistance to standard treatment. With urgent operative interventions and novel endoscopic approaches, pseudomembranous colitis is being seen more commonly in surgical practices.

DATA SOURCES

In this paper, we will review a number of papers from the literature. We will discuss the epidemiology, evaluation and treatment of Clostridium difficile infection. Fulminant colitis may require emergency operation. For the surgical endoscopist, fecal microbiota transplantation restores the gastrointestinal flora, and has been shown to be effective in more than 80% of patients.

CONCLUSION

Clostridium difficile infection is a major cause of healthcare-related diarrhea leading to increased morbidity and mortality in surgical patients. Increases in failure rates and resistance to current treatments are clinical and economic challenges in the healthcare situation.