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Published on: December 10, 2016
Antimicrobial susceptibility of Clostridium difficile isolated from neonatal pigs with enteritis
1Rollins Animal Disease Diagnostic Laboratory, North Carolina Department of Agriculture and Consumer Services, Raleigh, NC 27601, USA.
Abstract:
The minimum inhibitory concentration (MIC) of eight antimicrobial agents was determined by the agar dilution method for 80 isolates of Clostridium difficile from neonatal pigs with enteritis. MICs(50) for erythromycin, tilmicosin, and tylosin were relatively low (0.25-0.50 microg/mL), but MICs(90) (64 or > or =256 microg/mL) suggest in vivo resistance of a proportion of isolates. Susceptibility to tetracycline varied widely, with MIC(50) and MIC(90) of 8 and 32 microg/mL, respectively. The MICs(90) for tiamulin (8 microg/mL) and virginiamycin (16 microg/mL) suggest moderate susceptibility. Bacitracin and ceftiofur (MICs(90) > or =256 microg/mL) have little activity against C. difficile. Tiamulin and virginiamycin may decrease fecal shedding of C. difficile by sows, and erythromycin, tetracycline, and tylosin may be useful for treatment of infected piglets.
Insights
Clostridium difficile isolates from pigs show varied antimicrobial susceptibility. Tiamulin and virginiamycin show promise for reducing shedding, while erythromycin, tetracycline, and tylosin may treat infections.
Area of Science:
- Veterinary Microbiology
- Antimicrobial Resistance
- Swine Health
Background:
- Clostridium difficile causes enteritis in neonatal pigs.
- Antimicrobial susceptibility data is crucial for effective treatment and control.
Purpose of the Study:
- To determine the minimum inhibitory concentrations (MICs) of eight antimicrobial agents against Clostridium difficile isolates from pigs.
- To evaluate the potential efficacy of these agents for treating and controlling C. difficile infections in swine.
Main Methods:
- Agar dilution method used to determine MICs.
- 80 isolates of Clostridium difficile from neonatal pigs with enteritis were tested.
- MIC50 and MIC90 values were calculated for each agent.
Main Results:
- Erythromycin, tilmicosin, and tylosin showed low MIC50 but high MIC90, indicating potential resistance in some isolates.
- Tetracycline susceptibility varied widely.
- Tiamulin and virginiamycin demonstrated moderate susceptibility, while bacitracin and ceftiofur showed little activity.
- MIC90 values for erythromycin, tilmicosin, and tylosin were 64 or >=256 microg/mL.
Conclusions:
- Tiamulin and virginiamycin may reduce fecal shedding of C. difficile in sows.
- Erythromycin, tetracycline, and tylosin could be useful for treating infected piglets.
- Bacitracin and ceftiofur are not recommended for C. difficile treatment in this context.
