Failure of Metronidazole

Q: The cause of metronidazole failure in the treatment of Clostridioides difficile infection (CDI) is the development of resistance due to overuse? (select one) 

A) True 
B) False 


 Answer: B 

The actual reason behind the sub-optimal response to metronidazole in CDI is the decrease stool drug level. Metronidazole is very well absorbed and as the colonic infection starts to subside, drug get intestinally absorbed, resulting in decrease stool level and poor response. In contrast oral vancomycin or fidaxomicin are poorly absorbed resulting in higher drug stool level and excellent clinical response.

#infectiousdiseases
#gastroenterology
#pharmacology


References: 

1. Hu MY, Maroo S, Kyne L, et al. A prospective study of risk factors and historical trends in metronidazole failure for Clostridium difficile infection. Clin Gastroenterol Hepatol 2008; 6:1354.

2. Bolton RP, Culshaw MA. Faecal metronidazole concentrations during oral and intravenous therapy for antibiotic associated colitis due to Clostridium difficile. Gut 1986; 27:1169. 

3. Johnson S, Homann SR, Bettin KM, et al. Treatment of asymptomatic Clostridium difficile carriers (fecal excretors) with vancomycin or metronidazole. A randomized, placebo-controlled trial. Ann Intern Med 1992; 117:297. 

4. Brazier JS, Fawley W, Freeman J, Wilcox MH. Reduced susceptibility of Clostridium difficile to metronidazole. J Antimicrob Chemother 2001; 48:741.