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Antibiotic susceptibility of Clostridium difficile

Abstract number: R2242

Objectives: Reports of resistance to metronidazole and intermediate resistance to vancomycin emphasize the need for surveillance of antibiotic susceptibilities of C. difficile, CD027 and other hyper virulent or epidemic strains. The aim of the study was to evaluate the use of disk diffusion in detecting resistance against C. difficile.

Methods: Primary clinical isolates of C. difficile (n = 122) from Danish hospitalised patients with diarrhoea in 2008 were characterized by E-test and disk diffusion. The isolates were tested against vancomycin, metronidazole, clindamycin, erythromycin, and moxifloxacin as recommended in Denmark. Disk diffusion method was performed on both Anaerobe agar (Statens Serum Institut, Denmark) and Sensitivity agar with NAD (Biomérieux). MIC determination by E-test was performed on Brucella agar (Statens Serum Institut, Denmark). Disk diffusion was compared to E-test by linear regression and using interpretive criteria available from the CLSI.

Results: All strains were susceptible to metronidazole and vancomycin with MIC < 2 mg/L.

See Table.

There was an acceptable to good correlation between findings from disk diffusion and E-test for all antibiotics on both media, but for clindamycin we found an unacceptable high frequency of VME and ME.

Conclusions: Disk diffusion was a reliable method when evaluating susceptibility to moxifloxacin and erythromycin. However, disk diffusion was inadequate for the detection of clindamycin resistance and should therefore be supplemented with either E-test or broth dilution method.

Table. Antibiotic susceptibility of C. difficile and correlation between E-test and disk diffusion

Antimicrobial agentMIC (mg/L)Susceptibler2VME1 (%)ME2 (%)
 MIC 50Range(%)NAD3AA4NADAANADAA
Clindamycin40.75–256860.650.593445
Erythromycin0.380.094–256890.800.81000.80.8
Moxifloxacin0.750.25–32890.720.760000
1VME: Very major error. Sensitive by disk diffusion. Resistant by E-test. 2ME: Major error. Resistant by disk diffusion. Sensitive by E-test. 3NAD: Sensitivity agar with NAD. 4AA: Anaerobe agar.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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