Abstract
IntroductionWe investigated the changing trend of various toxigenic Clostridium difficile isolates at a 3 500-bed hospital in Taiwan. Genetic relatedness and antimicrobial susceptibility of toxigenic C. difficile isolates were also examined.MethodsA total of 110 non-repeat toxigenic C. difficile isolates from different patients were collected between 2002 and 2007. Characterization of the 110 toxigenic isolates was performed using agar dilution method, multilocus variable-number tandem-repeat analysis (MLVA) genotyping, tcdC genotyping, and toxinotyping.ResultsAmong the 110 toxigenic isolates studied, 70 isolates harbored tcdA and tcdB (A+B+) and 40 isolates harbored tcdB only (A−B+). The annual number of A+B+ isolates considerably increased over the 6-year study (P = 0.055). A total of 109 different MLVA genotypes were identified, in which A+B+ isolates and A−B+ isolates were differentiated into two genetic clusters with similarity of 17.6%. Twenty-four (60%) of the 40 A−B+ isolates formed a major cluster, MLVA-group 1, with a similarity of 85%. Seven (6.4%) resistant isolates were identified, including two metronidazole-resistant and five vancomycin-resistant isolates.ConclusionsThis study indicated a persistence of a MLVA group 1 A−B+ isolates and an increase of A+B+ isolates with diverse MLVA types. Moreover, C. difficile isolates with antimicrobial resistance to metronidazole or vancomycin were found to have emerged. Continuous surveillance is warranted to understand the recent situation and control the further spread of the toxigenic C. difficile isolates, especially among hospitalized patients.
Highlights
We investigated the changing trend of various toxigenic Clostridium difficile isolates at a 3 500-bed hospital in Taiwan
C. difficile isolates with antimicrobial resistance to metronidazole or vancomycin were found to have emerged
[1] C. difficile-associated disease (CDAD) has been an increasing problem in health care, especially because hypervirulent strains have emerged in North America and Europe over the past 10 years. [2,3,4] The pathogenicity of C. difficile is primarily based on the action of at least one of the two major exotoxins produced and secreted by the bacteria, i.e., toxin A and toxin B, which are encoded by the tcdA and tcdB gene, respectively. [5,6] In addition, some C. difficile isolates produce a binary toxin called CDT, which is an actinADP-ribosylating toxin
Summary
We investigated the changing trend of various toxigenic Clostridium difficile isolates at a 3 500-bed hospital in Taiwan. Clostridium difficile is an anaerobic, gram-positive, spore-forming bacillus It is one of the most common nosocomial pathogens identified and is the primary cause of antibiotic-associated diarrhea. Laboratory diagnosis of CDAD is currently achieved by isolation of toxigenic C. difficile isolates from stool samples and detecting the produced toxins. [13] A highly sensitive real-time PCR method for the rapid detection of toxigenic C. difficile in stool samples had been used for diagnosing CDAD. [17] As previous reports have indicated, C. difficile clinical isolates were sensitive to metronidazole or vancomycin, [18] clinical laboratories do not routinely perform antimicrobial susceptibility tests on this organism. [19] Poor outcomes of metronidazole therapy in CDAD were recently reported, [4,20] which suggests that the drug resistance pattern of C. difficile may be changing Up to 6.3% of toxin-producing isolates with resistance to metronidazole, and 3% with intermediate resistance to vancomycin were reported. [19] Poor outcomes of metronidazole therapy in CDAD were recently reported, [4,20] which suggests that the drug resistance pattern of C. difficile may be changing
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