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Updated: Jun 20, 2026
A Protocol to Characterize the Morphological Changes of Clostridium difficile in Response to Antibiotic Treatment
Published on: May 25, 2017
In vitro susceptibility to 17 antimicrobials of clinical Clostridium difficile isolates collected in 1993-2007 in
T Norén1, I Alriksson, T Akerlund
1Department of Infectious Diseases, Orebro University Hospital, SE-701 85 Orebro, Sweden. torbjorn.noren@orebroll.se
Abstract:
This study investigated the MICs of 17 antimicrobials, for 606 toxigenic clinical isolates of Clostridium difficile collected between 1993 and 2007 in Sweden. Low MIC(90) values were found for metronidazole (0.5 mg/L), vancomycin (1.0 mg/L), teicoplanin (0.125 mg/L), fusidic acid (1.0 mg/L), linezolid (2.0 mg/L), daptomycin (2.0 mg/L) and tigecycline (0.064 mg/L). Three isolates (0.5%) had elevated MICs for vancomycin (4-8 mg/L); however, these isolates originated from the same patient, who was receiving long-term intravenous vancomycin treatment. High-level clindamycin resistant isolates (MIC >256 mg/L) peaked in 1997 with 39 of 95 (41%) and out of these, 36% were also highly resistant to erythromycin. beta-Lactams such as penicillin V and piperacillin displayed MIC(90)s of 8 and 32 mg/L, respectively, whereas MICs of cefuroxime were >256 mg/L for all isolates. Universal resistance to ciprofloxacin and levofloxacin was found, and resistance to moxifloxacin increased from 4% of isolates in 2004 to 23% in 2007. Notably, these moxifloxacin-resistant isolates did not belong to the recent epidemic PCR ribotype 027, but to the pre-existing epidemic type 012 (82%), and these isolates accounted for the majority of isolates that were resistant to clindamycin (70%), tetracycline (84%) and rifampicin (92%) as well. This investigation of susceptibility data on clinical C. difficile isolates showed variations of multiresistance to be due to a specific PCR ribotype 012, emphasizing the importance of genotyping when evaluating emerging resistance over time.
Insights
This study tracked Clostridium difficile antimicrobial resistance in Sweden from 1993-2007. Multidrug resistance was linked to PCR ribotype 012, highlighting the need for genotyping in tracking emerging resistance.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Clostridium difficile infections (CDI) pose a significant healthcare challenge.
- Understanding antimicrobial susceptibility patterns is crucial for effective treatment and infection control.
Purpose of the Study:
- To investigate the minimum inhibitory concentrations (MICs) of various antimicrobials against clinical isolates of Clostridium difficile.
- To analyze trends in antimicrobial resistance and identify factors contributing to multidrug resistance.
Main Methods:
- Collected 606 toxigenic Clostridium difficile isolates from Sweden between 1993 and 2007.
- Determined MICs for 17 different antimicrobials.
- Utilized PCR ribotyping to characterize isolates and identify epidemic strains.
Main Results:
- Low MIC90 values were observed for metronidazole, vancomycin, teicoplanin, fusidic acid, linezolid, daptomycin, and tigecycline.
- High-level resistance to clindamycin and erythromycin was noted, peaking in 1997.
- Universal resistance to ciprofloxacin and levofloxacin was found, with increasing moxifloxacin resistance.
- Multidrug resistance, including to clindamycin, tetracycline, and rifampicin, was predominantly associated with PCR ribotype 012 isolates.
Conclusions:
- Antimicrobial susceptibility of Clostridium difficile isolates shows temporal variations.
- PCR ribotype 012 is a key factor in the emergence of multidrug resistance.
- Genotyping is essential for accurately evaluating and monitoring antimicrobial resistance trends in Clostridium difficile.
