Can metronidazole still be used for treatment of Clostridium difficile infections?

Efficacy of metronidazole versus placebo in pain control after hemorrhoidectomy. Results of a controlled clinical trial

INTRODUCTION

Hemorrhoidal disease occurs in 50% of people aged > 40 years and is the most common reason for anorectal surgery. Pain is the main complication. Multiple topical and systemic drugs have been investigated for pain control, but there is no ideal treatment. Metronidazole has been shown to decrease postoperative pain but is not used widely.

OBJECTIVE

To evaluate the effect of oral metronidazole versus placebo and to assess postoperative pain following hemorrhoidectomy.

MATERIAL AND METHODS

Controlled clinical trial in adult patients who underwent elective hemorrhoidectomy for grade III/IV hemorrhoids. Patients were assigned to receive metronidazole (500 mg q8 h orally; study group, SG) or placebo (control group, CG) for 7 days after surgery. Pain was assessed using a visual analog scale after surgery. Analgesic administration (time and use of analgesics) and resumption of daily life activities were also assessed.

RESULTS

Forty-four patients were included, 22 in each group. Postoperative pain differed significantly between the SG and CG at 6 h (3.86 ± 0.56, 6.64 ± 1.49), 12 h (5.59 ± 1.33, 8.82 ± 0.79), 24 h (6.86 ± 1.49, 9.73 ± 0.45), day 4 (5.32 ± 2.10, 9.50 ± 0.59), day 7 (3.14 ± 1.03, 7.36 ± 1.39), and day 14 (2.14 ± 0.46, 5.45 ± 1.29). The first analgesia dose was required at 21.27 ± 5.47 h in the CG and 7.09 ± 2.36 h in the SG (p < 0.05), the time of analgesic use was 6.86 ± 1.61 days in the CG and 13.09 ± 2.48 days in the SG (p < 0.05), and resumption of daily activities occurred at 7.59 ± 1.56 days in the CG and 14.73 ± 3.76 days in the SG (p < 0.05).

CONCLUSION

Oral administration of metronidazole is effective in pain management after hemorrhoidectomy.

Clostridium difficile infection in the twenty-first century

Clostridium difficile is a spore-forming gram-positive bacillus, and the leading cause of antibiotic-associated nosocomial diarrhea and colitis in the industrialized world. With the emergence of a hypervirulent strain of C. difficile (BI/NAP1/027), the epidemiology of C. difficile infection has rapidly changed in the last decade. C. difficile infection, once thought to be an easy to treat bacterial infection, has evolved into an epidemic that is associated with a high rate of mortality, causing disease in patients thought to be low-risk. In this review, we discuss the changing face of C .difficile infection and the novel treatment and prevention strategies needed to halt this ever growing epidemic.

Antimicrobial susceptibility testing of Clostridium difficile using EUCAST epidemiological cut-off values and disk diffusion correlates

With the emergence of reduced susceptibility of Clostridium difficile to metronidazole and vancomycin the value of antimicrobial susceptibility testing has increased. The aim of our study was to evaluate disk diffusion for susceptibility testing of C. difficile by comparing disk diffusion results with MICs from gradient tests and to propose zone diameter breakpoint correlates for the EUCAST epidemiological cut-off values (ECOFFs) recently published. We tested 211 clinical isolates of C. difficile, from patients with diarrhoea hospitalized at Aarhus and Odense University Hospitals, Denmark. Furthermore, ten clinical isolates of C. difficile from the Anaerobe Reference Laboratory, University Hospital of Wales, with known reduced susceptibility to either metronidazole or vancomycin, were included. Isolates were tested with Etest gradient strips and disk diffusion towards metronidazole, vancomycin and moxifloxacin on Brucella Blood Agar supplemented with hemin and vitamin K. We found an excellent agreement between inhibition zone diameter and MICs. For each MIC value, the inhibition zones varied from 0 to 8 mm, with 93% of values within 6 mm for metronidazole, 95% of values within 4 mm for vancomycin, and 98% of values within 4 mm for moxifloxacin. With proposed zone diameter breakpoints for metronidazole, vancomycin and moxifloxacin of WT ≥ 23 mm, WT ≥ 19 and WT ≥ 20 mm, respectively, we found no very major errors and only major errors below 2%. In conclusion, we suggest that disk diffusion is an option for antimicrobial susceptibility testing of C. difficile.

Anaerobic infections: update on treatment considerations

Anaerobic bacteria are the predominant indigenous flora of humans and, as a result, play an important role in infections, some of which are serious with a high mortality rate. These opportunistic pathogens are frequently missed in cultures of clinical samples because of shortcomings in collection and transport procedures as well as lack of isolation and susceptibility testing of anaerobes in many clinical microbiology laboratories. Correlation of clinical failures with known antibacterial resistance of anaerobic bacteria is seldom possible. Changes in resistance over time, and the discovery and characterization of resistance determinants in anaerobic bacteria, has increased recognition of problems in empirical treatment and has even resulted in changes in treatment guidelines. This review discusses the role of anaerobic bacteria in the normal flora of humans, their involvement in different mixed infections, developments in antibacterial resistance of the most frequent anaerobic pathogens and possible new treatment options.

Antimicrobial resistance in Clostridium difficile

Clostridium difficile is the leading cause of hospital-acquired diarrhoea and the number of outbreaks has risen markedly since 2003. The emergence and spread of resistance in C. difficile is complicating treatment and prevention. Most isolates are still susceptible to vancomycin and metronidazole (MTZ), however transient and heteroresistance to MTZ have been reported. The prevalence of resistance to other antimicrobial agents is highly variable in different populations and in different countries, ranging from 0% to 100%. Isolates of common polymerase chain reaction (PCR) ribotypes are more resistant than uncommon ribotypes. Most of the resistance mechanisms that have been identified in C. difficile are similar to those in other Gram-positive bacteria, including mutation, selection and acquisition of the genetic information that encodes resistance. Better antibiotic stewardship and infection control are needed to prevent further spread of resistance in C. difficile.