Antimicrobial susceptibility and molecular epidemiology of Clostridium difficile (CD) isolated from faecal CD toxin-positive patients in a UK teaching hospital
Abstract number: P1780
Clark M., Levi K., Soo S., Towner K.
Objectives:Clostridium difficile causes a range of important nosocomial infections varying from diarrhoea to pseudomembranous colitis, known collectively as C. difficile-associated disease (CDAD). In Nottingham University Hospitals NHS Trust there has been an increase in severe cases of CDAD, which, in turn, has increased morbidity and mortality. At present CDAD is diagnosed using enzyme immunoassay, but this does not provide any information on antibiotic susceptibility or epidemiology. This study aimed to determine the local epidemiology and antimicrobial susceptibility of C. difficile in Nottingham.
Methods: Between 1 April and 8 June 2006, 100 C. difficile toxin-positive faecal samples were cultured using the alcohol shock method. Susceptibilities to metronidazole, vancomycin, cefuroxime, moxifloxacin and erythromycin were determined using a modified Stoke's method, and the isolates were typed using 1623S rRNA PCR-ribotyping. Isolates that were non-UK epidemic ribotypes were examined by PCR for the toxin A and toxin B genes; isolates that were toxin A-negative were further examined for deletions in the toxin A gene.
Results: All 100 isolates were metronidazole-sensitive, vancomycin-sensitive and cefuroxime-resistant. Most (n = 86) isolates were moxifloxacin-resistant and 82 isolates were erythromycin-resistant. In total, 61 isolates belonged to ribotype 106, 18 to ribotype 027, seven to ribotype 001, and 14 to other non-UK epidemic ribotypes. The majority of the non-UK epidemic ribotypes (11/14) were toxin A-positive and all were toxin B-positive. PCR amplification of the toxin A gene (tcdA) demonstrated two different deletions in the 3'-end of the tcdA gene.
Conclusion: The predominant local epidemic strain of C. difficile belonged to ribotype 106. Ciprofloxacin, erythromycin and cefuroxime are commonly prescribed antibiotics in Nottingham, and this antibiotic policy is likely to be a contributing factor to the selection of antibiotic-resistant C. difficile ribotypes in Nottingham. There is evidence that the tcdA-negative isolates detected in this study may have novel deletions in the tcdA gene, and that these isolates may play a role in the evolving local epidemiology of CDAD.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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