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At least 451 records · Page 25Linked to original sources
PubMed1994

Specific detection of Clostridium difficile toxin A gene sequences in clinical isolates.

The polymerase chain reaction (PCR) was used to specifically detect toxin A gene sequences of Clostridium difficile in DNA isolated from human faeces. A set of oligonucleotide primers derived from the non-repetitive region of the toxin A gene was developed to amplify a 634-bp DNA fragment. All 28 cytotoxic strains of C. difficile, previously characterized by a toxin B-PCR assay, were positive for the presence of toxin A gene sequences. No amplification products were obtained from DNAs extracted from non-toxigenic strains, strains of C. sordellii, or C. bifermentans. In addition, amplification of DNA extracted from C. difficile 8864, a strain which does not produce toxin A, resulted in multiple bands which probed negative for toxin A gene sequences. DNAs extracted from nine stool specimens which were positive for toxin B by the cytotoxicity assay and by the toxin B-PCR assay were also positive in this assay. Toxin A gene sequences were detected in DNAs obtained from 4/11 stool specimens which were negative by the toxin B cytotoxicity assay. These four specimens were from patients who had a history of relapses due to C. difficile-associated colitis, and whose stools had previously been found to be positive by the toxin B-PCR test despite no detectable toxin B in the specimens. These data indicate a comparable degree of clinical sensitivity between these two toxin-gene PCR-based assays. This rapid, sensitive and specific assay may be useful not only in the diagnosis of C. difficile infections, but also in molecular studies of the toxin A gene in C. difficile strains.

Bacterial Proteins↗
PubMed1994

Gene cloning in Clostridium difficile using Tn916 as a shuttle conjugative transposon.

A pBR322-based vector, pCI195, containing a 4.2-kb region of the conjugative transposon Tn919 was used as a vector for gene cloning in Clostridium difficile. The plasmid was found to integrate into the chromosome of a Bacillus subtilis strain that contained Tn916 delta E. Southern blot analysis of the recombinant demonstrated that pCI195 had inserted into Tn916 delta E by a recombination event. The transposon::plasmid structure could be transferred, by filter mating, from B. subtilis to C. difficile (at a frequency of 10(-8) per donor), where it entered the chromosome at a specific site. Segregation of plasmid and transposon markers was observed on transfer, although the Tn916 delta E::pCI195 was stably maintained in C. difficile. To demonstrate that pCI195 could be used for gene cloning in C. difficile, a 1.1-kb fragment of the C. difficile toxin B gene was cloned into pCI195 to generate pPPM100. Tn916 delta E::pPPM100 was transferred into a nontoxigenic C. difficile strain by filter mating, where it entered the genome at a specific site. pCI195 should be useful as a general cloning vector for C. difficile, as the transposon::plasmid structure could be transferred to different C. difficile strains. This is the first report of gene cloning in C. difficile.

Bacillus subtilis↗
PubMed1994

Pneumatosis intestinalis in a child with AIDS and pseudomembranous colitis.

Pneumatosis intestinalis (PI) was first reported in three children and one adult with acquired immune deficiency syndrome (AIDS) in 1990. The microorganisms cultured from these patients included Cryptosporidium, rotavirus, cytomegalovirus, and Pseudomonas. We report the fourth child with AIDS and PI, and the first with PI to be associated with Clostridium difficile colitis.

AIDS-Related Opportunistic Infections↗
PubMed1996

Relapses or reinfections: analysis of a case of Clostridium difficile-associated colitis by two typing systems.

Immunoblotting and pulsed-field gel electrophoresis of Clostridium difficile isolates were employed to differentiate reinfection by a newly acquired strain from relapse by an original strain in a 10-year-old patient with four episodes of C. difficile-associated colitis. Immunoblot typing demonstrated subserogroup K-1 of serogroup K for the first and second organisms, subserogroup A-1 of serogroup A for the third organism, and subserogroup G-4 of serogroup G for the fourth organism. PFGE analysis revealed consistent results with immunoblot analysis except that the strains from the fourth episode, whose DNA constantly degraded, were nontypable by this method. Five separate isolates of C. difficile from a specimen of each episode showed identical PFGE patterns, indicating that infections of multiple strains probably did not occur in this patient. These typing results suggested that the second episode after a 17-day course of vancomycin therapy represented a relapse by the strain causing the first episode, and that the third and fourth episodes after tapering vancomycin therapy were reinfections by other strains. Both immunoblot and PFGE typing systems are promising tools for analyzing recurrence of C. difficile infection.

Anti-Bacterial Agents↗
PubMed2000

Environmental control to reduce transmission of Clostridium difficile.

Restrictive antibiotic policies and infection control measures have been shown to reduce the incidence of Clostridium difficile-associated diarrhea (CDAD) among hospitalized patients. To date, the role of environmental disinfectants in reducing nosocomial CDAD rates has not been well studied. In a before-and-after intervention study, patients in 3 units were evaluated to determine if unbuffered 1:10 hypochlorite solution is effective as an environmental disinfectant in reducing the incidence of CDAD. Among 4252 patients, the incidence rate of CDAD for bone marrow transplant patients decreased significantly, from 8.6 to 3.3 cases per 1000 patient-days (hazard ratio, 0.37; 95% confidence interval, 0.19-0.74), after the environmental disinfectant was switched from quaternary ammonium to 1:10 hypochlorite solution in the rooms of patients with CDAD. Reverting later to quaternary ammonium solution increased the CDAD rate to 8.1 cases per 1000 patient-days. No reduction in CDAD rates was seen among neurosurgical intensive care unit and general medicine patients, for whom baseline rates were 3.0 and 1.3 cases per 1000 patient-days, respectively. Unbuffered 1:10 hypochlorite solution is effective in decreasing patients' risk of developing CDAD in areas where CDAD is highly endemic. Presumed mechanisms include reducing the environmental burden and the potential for C. difficile transmission among susceptible patients.

Adult↗