Severe Clostridium difficile associated disease is associated with outbreaks of the recently described BI/NAP1 epidemic clone. This clone is characterized by an 18-bp deletion in the tcdC gene and increased production of toxins A and B in vitro. TcdC is a putative negative regulator of toxin A&B production. We characterized tcdC genotypes from a collection of C. difficile isolates from a hospital that experienced an outbreak caused by the BI/NAP1 epidemic clone. Sequence analysis of tcdC was performed on DNA samples isolated from 199 toxigenic C. difficile isolates (31% BI/NAP1) from 2001 and 2005. Sequences obtained from 36 (18.6%) isolates predicted wild-type TcdC (232 amino acid residues), whereas 12 (6.1%) isolates had tcdC genotypes with previously described 18-or 39-bp deletions. The remaining isolates comprised 15 unique genotypes. Of these, 5 genotypes contain 18-or 36-bp deletions. Of these five genotypes, one is characterized by a single nucleotide deletion at position 117 resulting in a frameshift that introduces a stop codon at position 196, truncating the predicted TcdC to 65 amino acid residues. All 62 of the isolates in this collection comprising the epidemic clone are characterized by this genotype. This result suggests that severe truncation of TcdC is responsible for the increased toxin production observed in strains belonging to the BI/NAP1 clone and that the 18-bp deletion is probably irrelevant to TcdC function. Further investigations are required to determine the effect of this and other tcdC genotypes on toxin production and clinical disease.

Background. In June 2000, the hospital-acquired Clostridium difficile (CD) infection rate in our hospital (University of Pittsburgh Medical Center-Presbyterian, Pittsburgh, PA) increased to 10.4 infections per 1000 hospital discharges (HDs); the annual rate increased from 2.7 infections per 1000 HDs to 7.2 infections per 1000 HDs and was accompanied by an increase in the frequency of severe outcomes. Forty-seven (51%) of 92 HA CD isolates in 2001 were identified as the "epidemic BI strain." A comprehensive CD infection control "bundle" was implemented to control the outbreak of CD infection.Methods. The CD infection control bundle consisted of education, increased and early case finding, expanded infection-control measures, development of a CD infection management team, and antimicrobial management.Process measures, antimicrobial usage, and hospital-acquired CD infection rates were analyzed, and CD isolates were typed.Results. The rates of compliance with hand hygiene and isolation were 75% and 68%, respectively. The CD management team evaluated a mean of 31 patients per month (11% were evaluated for moderate or severe disease). Use of antimicrobial therapy associated with increased CD infection risk decreased by 41% during the period 2003-2005 (). The aggregate rate of CD infection during the period 2001-2006 decreased to 4.8 infections per 1000 P ! .001 HDs (odds ratio, 2.2; 95% confidence interval, 1.4-3.1;) and by 2006, was 3.0 infections per 1000 HDs, a P ! .001 rate reduction of 71% (odds ratio, 3.5; 95% confidence interval, 2.3-5.4;). During the period 2000-2001, P ! .001 the proportion of severe CD cases peaked at 9.4% (37 of 393 CD infections were severe); the rate decreased to 3.1% in 2002 and further decreased to 1.0% in 2006-a 78% overall reduction (odds ratio, 20.3; 95% confidence interval, 2.8-148.2; ). In 2005, 13% of CD isolates were type BI (20% were hospital acquired), which represented a P ! .001 significant reduction from 2001 ( ). P ! .001 Conclusions. The outbreak of CD infection with the BI strain in our hospital was controlled after implementing a CD infection control "bundle." Early identification, coupled with appropriate control measures, reduces the rate of CD infection and the frequency of adverse events.

Clostridium difficile is a major cause of antibiotic-associated gastrointestinal illness. Recently, an increased incidence of hospital-acquired infections with severe outcomes has been reported in North America and Europe. Current molecular-typing methods for detection of outbreaks and nosocomial transmission are labor-intensive, subjective, or insufficiently discriminatory to differentiate between closely related strains. This report describes the development of multilocus variable-number tandem-repeat (VNTR) analysis (