Characterization of clinical Clostridium difficile isolates by PCR ribotyping and detection of toxin genes in Austria, 2006-2007

In order to assess the lethality of Clostridium difficile-associated disease (CDAD) and the PCR ribotypes prevalent in Austria, the Austrian Agency for Health and Food Safety requested isolates of C. difficile from patients in a structured but arbitrary sampling scheme. In the allocated period from February 2006 to January 2007, local hospital laboratories within each of the nine provinces were asked to submit C. difficile isolates from at least ten cases of CDAD. Confirmation of species identification, toxin detection, susceptibility testing against four antimicrobial agents and typing using a PCR ribotyping method were performed at the reference laboratory. In total, 149 isolates of putative C. difficile were submitted, from which 142 were included for study. Antimicrobial susceptibility patterns revealed resistance to clindamycin in 57% and high-level resistance to moxifloxacin in 38% of isolates tested. CDAD manifested as diarrhoea (including eight cases of bloody diarrhoea) in 126 cases (88.7%), as pseudomembranous colitis in 15 cases (10.6%) and as toxic megacolon in one case. Twelve of the 142 patients died within 30 days of specimen collection (8.45% lethality). A lethal outcome occurred in 2/15 cases (113.3%) when pseudomembranous colitis was present and in 10/126 cases (7.9%) in the absence of pseudomembranous colitis or toxic megacolon. Among the 142 isolates from 25 health-care facilities, 41 PCR ribotype patterns were found. The most frequent ribotypes were Al-5 (including six lethal cases out of 26 patients), 014 (two out of 24) and 053 (one out of 24). The typing patterns demonstrated the occurrence of clusters in hospitals.