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PubMed2000

Characterization of surface layer proteins from different Clostridium difficile clinical isolates.

In a previous study we suggested that two surface proteins of a Clostridium difficile strain were involved in the formation of a regularly assembled surface layer (S-layer) external to the cell wall. In the present paper six C. difficile strains isolated from cases and healthy carriers were studied. By using freeze-etching and negative staining techniques two superimposed structurally different lattices were detected on the cell surface of the different C. difficile strains. In each strain, the outer S-layer lattice was arranged in a square symmetry and the inner S-layer lattice in hexagonal symmetry. The S-layer proteins from the different strains were isolated and characterized. Each strain showed two distinct S-layer glycoproteins ranging in molecular mass 36-56 kDa. Antigenic cross-reactivity among the S-layer proteins of higher molecular masses extracted from each strain was demonstrated whereas no antigenic relationship was observed among the different S-layer proteins of lower molecular masses. N-terminal sequence analysis showed the presence of common structural motifs conserved among the high S-layer proteins as well as among the low S-layer proteins. These data indicate that the presence of S-layer on C. difficile strains is common and that its glycoprotein subunits show a certain degree of heterogeneity.

Adult↗

PubMed2000

Pseudomembranous colitis: report of a severe case with unusual clinical signs in a young nurse.

We describe the case of a young and otherwise healthy nurse who developed pseudomembranous colitis ten days after receiving oral clindamycin for dental infection. Her clinical course was particularly stormy and was characterized by severe diarrhea and vomiting, profuse ascites, pleural effusion, abdominal tenderness, peritoneal irritation, and systemic toxicity. The Clostridium difficile assay was negative on two occasions. Features compatible with pseudomembranous colitis were seen at sigmoidoscopy, and the diagnosis was confirmed by biopsies.

Adult↗

PubMed1997

Physical map of the Clostridium difficile chromosome.

Clostridium difficile is a causative agent in antibiotically induced diarrhea and pseudomembraneous colitis. The ability of strains of C. difficile to cause disease depends upon the presence of two toxin genes and their corresponding proteins, designated toxin A and toxin B. Previous studies conducted in this laboratory indicated that toxigenic strains of C. difficile possess both toxin genes, whereas non-toxigenic strains do not. Likewise, the studies showed that toxigenic and non-toxigenic strains of C. difficile differ significantly in chromosomal organization by ribotype analysis. Therefore, the chromosomal organization of a reference strain was investigated. Pulsed field gel electrophoresis was utilized to generate a physical map of the chromosome of the toxigenic Clostridium difficile strain ATCC 43594. Restriction digestions of whole chromosomes with the enzymes NruI and SacII generated consistent macrofragment profiles. NruI digestion resulted in 14 discernible bands containing 16 fragments of DNA. SacII digestions resulted in 14 discernible bands containing 15 fragments of DNA. Restriction digestions with both SacII and NruI resulted in 21 discernible bands containing 31 fragments of DNA. Probing of single and double digests with an extensive set of NruI and SacII single- and double-digest bands clarified the location of individual fragments in relation to one another, resulting in a restriction map of the chromosome. PCR-generated probes of five loci of C. difficile were used to map the location of seven genes on the chromosome. Finally, the addition of all fragments from NruI, SacII and NruI/SacII digestions resulted in an approximate chromosome size of 4.4 Mb.

Chromosomes, Bacterial↗

PubMed2001

Extra-intestinal infections caused by Clostridium difficile.

The objective of this paper was to investigate the incidence of extra-intestinal infections caused by Clostridium difficile. During a 10-year period, the microbiology laboratory of our institution isolated 2034 isolates of C. difficile. Of the 2034 isolates, 21 (1.08%) were obtained from extra-intestinal sources. This represents an incidence of extra-intestinal isolation of four cases per 100 000 admissions. We were able to review the records of 17 patients for our study. The isolates in 12 patients were obtained from structures or fluids anatomically close to the colon and included the following infections: peritonitis in five cases (three primary and two secondary), intra-abdominal abscesses in three patients and abdominal wound infections in four cases. The infections in the other five patients were not in the anatomic vicinity of the colon. They included one case with a brain abscess, two episodes of bacteremia and two cases of foot infections (one chronic osteomyelitis). In all but one case, C. difficile isolation was obtained as part of a polymicrobial flora. The isolates were frequently non-toxigenic and the extra-intestinal infections occurred without concomitant diarrhea or prior anti-microbial therapy. Out of the 17 patients, eight died and nine survived. Death could not be directly attributed to C. difficile in any of the cases. The isolation of C. difficile outside the intestinal tract is very uncommon. Its clinical significance should be interpreted with caution.

Abdominal Abscess↗

PubMed2002

Undetected vancomycin-resistant Enterococcus stool colonization in a Veterans Affairs Hospital using a Clostridium difficile-focused surveillance strategy.

We examined the point prevalence of undetected vancomycin-resistant Enterococcus (VRE) stool colonization in an institution that screens stool samples submitted for Clostridium difficile testing. Of 112 patients not known to be colonized, 10 (9%) had rectal VRE colonization. A prospective algorithm was effective for identification of colonized patients.

Algorithms↗

PubMed1997

Clostridium difficile infection is a risk factor for bacteremia due to vancomycin-resistant enterococci (VRE) in VRE-colonized patients with acute leukemia.

A cohort study was conducted in a cancer center to identify risk factors for bacteremia with vancomycin-resistant enterococci (VRE) in neutropenic cancer patients colonized with VRE. There were 10 patients with VRE bacteremia among 56 colonized with VRE, of whose charts 51 were available for review. One hundred percent of patients with VRE bacteremia (10 of 10) vs. 56% of patients without VRE bacteremia (23 of 41) had acute leukemia (P = .01, Fisher's exact test). Four of the 10 patients with VRE bacteremia had a positive Clostridium difficile toxin assay within 6 days of their first positive VRE blood culture. Both C. difficile infection and antimicrobial (vancomycin and ciprofloxacin) use during VRE colonization were significant risk factors for VRE bacteremia in univariate analysis. When a Cox proportional hazards model was used to account for differences in follow-up time, C. difficile infection was the only statistically significant risk factor (risk ratio, 8.2; P = .007) for VRE bacteremia in VRE-colonized patients with acute leukemia.

Acute Disease↗

PubMed1996

Increased incidence of Clostridium difficile-associated diarrhea following decreased restriction of antibiotic use.

Removal of antimicrobial agents from formulary restriction status at our center was followed by an increase in the incidence of Clostridium difficile-associated diarrhea. The mean monthly incidence of C. difficile diarrhea for the 12-month period before institution of decreased restriction of antibiotic use was 3.4 infections per 1,000 admissions and rose to 6.2 infections per 1,000 admissions during the following 4-month period (P < .05). Patients who developed disease before and after decreased restriction of antibiotics were similar in terms of the mean number of antimicrobial agents administered and mean duration of therapy. The most commonly administered agents whose use preceded the onset of disease were cefazolin, trimethoprim-sulfamethoxazole, ampicillin, ticarcillin/clavulanate, and gentamicin (the latter drug was always used in combination with other agents). Immunoblot typing indicated that there was no association between C. difficile strains and administration of specific agents. There was no coincidental epidemic to account for the increased incidence of infection. The increased incidence of C. difficile disease is a potential problem that may occur following removal of extended-spectrum antimicrobial agents from formulary restriction status.

Adult↗

PubMed1993

Detection of Clostridium difficile enterotoxin gene in clinical specimens by the polymerase chain reaction.

A rapid assay was developed for detection of the Clostridium difficile enterotoxin gene in stool specimens by means of the polymerase chain reaction (PCR). The PCR primers amplified a 63-bp repetitive sequence of the enterotoxin gene, thereby generating a distinctive ladder pattern of DNA bands following electrophoresis. Crude DNA extracts from stools containing C. difficile produced one (63-bp) or more bands of the characteristic ladder. Of 172 stool specimens from 58 patients, 37 gave positive results by culture (15 specimens) or cytotoxin assay (36 specimens). When 36 available "positive" specimens were tested by the PCR assay, 34 (94%) gave positive results--24 by direct testing, and 10 after extraction of DNA by the Qiagen procedure. Insufficient material of the remaining two specimens was available for DNA extraction. Of 21 stools "negative" for C. difficile by culture or cytotoxin assay, one gave a positive result by PCR and seven produced atypical bands. The rapid PCR detection technique for C. difficile was more sensitive than standard culture, and of a sensitivity similar to cytotoxin testing. The method has the potential for adoption in routine laboratory practice.

Bacterial Toxins↗

PubMed2006

Proton pump inhibitor therapy is a risk factor for Clostridium difficile-associated diarrhoea.

BACKGROUND: Inhibition of gastric acid removes a defence against ingested bacteria and spores, increasing the risk of some forms of gastroenteritis. Previous studies investigating a possible link between acid suppression therapy and Clostridium difficile-associated diarrhoea have reported conflicting results. AIM: To investigate whether acid suppression therapy is associated with an increased risk of C. difficile-associated diarrhoea. Prospective case-control study of 155 consecutive in-patients with C. difficile-associated diarrhoea. RESULTS: Antibiotics had been received by 143 (92%) of the C. difficile-associated diarrhoea group and 76 (50%) of the controls during the preceding 3 months. Among those receiving antibiotics, 59 (41%) of the C. difficile-associated diarrhoea group had also received acid suppression, compared with 21 (28%) of controls (OR 1.84, CI 1.01, 3.36, chi(2) = 4.0, P = 0.046). Among the entire C. difficile-associated diarrhoea group 64 (41%) had received acid suppression compared with 40 (26%) of controls (OR 1.99, CI 1.19, 3.31, chi(2) = 7.9, P = 0.005). Logistic regression analyses found that C. difficile-associated diarrhoea was independently associated with: antibiotic use (OR 13.1, 95% CI: 6.6, 26.1); acid suppression therapy (OR 1.90, 95% CI: 1.10, 3.29); and female sex (OR 1.79, 95% CI: 1.06, 3.04). CONCLUSIONS: The risk of C. difficile-associated diarrhoea in hospitalized patients receiving antibiotics may be compounded by exposure to proton pump inhibitor therapy.

Aged↗

PubMed2006

Are broad-spectrum fluoroquinolones more likely to cause Clostridium difficile-associated disease?

Limited evidence suggests that broad-spectrum fluoroquinolones such as gatifloxacin and moxifloxacin are more likely to cause Clostridium difficile-associated disease than levofloxacin. In a population-based case-control study of outpatients prescribed fluoroquinolones, we found no increased risk of C. difficile-associated disease requiring hospitalization among patients prescribed gatifloxacin or moxifloxacin compared to levofloxacin.

Aged↗

PubMed2001

Characterization of a cell surface protein of Clostridium difficile with adhesive properties.

Our laboratory has previously shown that Clostridium difficile adherence to cultured cells is enhanced after heat shock at 60 degrees C and that it is mediated by a proteinaceous surface component. The present study was undertaken to identify the surface molecules of this bacterium that could play a role in its adherence to the intestine. The cwp66 gene, encoding a cell surface-associated protein of C. difficile 79-685, was isolated by immunoscreening of a C. difficile gene library with polyclonal antibodies against C. difficile heated at 60 degrees C. The Cwp66 protein (66 kDa) contains two domains, each carrying three imperfect repeats and one presenting homologies to the autolysin CwlB of Bacillus subtilis. A survey of 36 strains of C. difficile representing 11 serogroups showed that the 3' portion of the cwp66 gene is variable; this was confirmed by sequencing of cwp66 from another strain, C-253. Two recombinant protein fragments corresponding to the two domains of Cwp66 were expressed in fusion with glutathione S-transferase in Escherichia coli and purified by affinity chromatography using gluthatione-Sepharose 4B. Antibodies raised against the two domains recognized Cwp66 in bacterial surface extracts. By immunoelectron microscopy, the C-terminal domain was found to be cell surface exposed. When used as inhibitors in cell binding studies, the antibodies and protein fragments partially inhibited adherence of C. difficile to cultured cells, confirming that Cwp66 is an adhesin, the first to be identified in clostridia.

Adhesins, Bacterial↗

PubMed2006

Comparative phylogenomics of Clostridium difficile reveals clade specificity and microevolution of hypervirulent strains.

Clostridium difficile is the most frequent cause of nosocomial diarrhea worldwide, and recent reports suggested the emergence of a hypervirulent strain in North America and Europe. In this study, we applied comparative phylogenomics (whole-genome comparisons using DNA microarrays combined with Bayesian phylogenies) to model the phylogeny of C. difficile, including 75 diverse isolates comprising hypervirulent, toxin-variable, and animal strains. The analysis identified four distinct statistically supported clusters comprising a hypervirulent clade, a toxin A(-) B(+) clade, and two clades with human and animal isolates. Genetic differences among clades revealed several genetic islands relating to virulence and niche adaptation, including antibiotic resistance, motility, adhesion, and enteric metabolism. Only 19.7% of genes were shared by all strains, confirming that this enteric species readily undergoes genetic exchange. This study has provided insight into the possible origins of C. difficile and its evolution that may have implications in disease control strategies.

Animals↗

PubMed1998

A novel toxinotyping scheme and correlation of toxinotypes with serogroups of Clostridium difficile isolates.

Two hundred nineteen Clostridium difficile isolates from 22 serogroups were screened for changes in the genes coding for toxin B (tcdB) and toxin A (tcdA). Parts of the toxin genes were amplified, and the PCR fragments were checked for length polymorphisms and cut with several restriction enzymes to monitor restriction fragment length polymorphisms (RFLPs). For 47 strains (21%), differences in the toxin genes were found compared to the toxin genes of reference strain VPI 10,463. Polymorphisms were usually observed in both toxin genes. RFLPs were more commonly found in the tcdB gene, in which a single restriction enzyme could give up to five different patterns. Restriction sites seemed to be less heterogeneous in the tcdA gene, in which for most enzymes only two different RFLPs were recognized. However, deletions were observed in tcdA, and four new types of shortened tcdA genes are described. According to the changes in their toxin genes, variant strains could be divided into 10 groups (toxinotypes I to X). A toxinotype was characterized by similar patterns of changes in the toxin genes and in other regions of the pathogenicity locus and also similar pulsed-field gel electrophoresis patterns. Variant toxinotypes were found in 9 of the 22 serogroups studied, and some toxinotypes were clearly associated with specific serogroups. Toxinotype VIII is characteristic for all strains of serogroup F. Other serogroups in which variant toxinotypes were commonly found are A1, A15, E, and X. Testing of variability in C. difficile toxin genes not only might be useful as a molecular typing system but also could have implications in diagnostics and pathogenesis.

Bacterial Proteins↗

PubMedDate not supplied

Hospital-acquired Clostridium difficile infection amongst ICU and burn patients in Kuwait.

OBJECTIVES: To prospectively study the prevalence of nosocomially acquired Clostridium difficile, a major cause of diarrhoea in hospitalized patients, in the intensive care units (ICUs) and burn unit (BUs) of three teaching hospitals in Kuwait. METHODS: During a 1-year prospective study, stool/rectal swabs were obtained from 344 patients admitted into the ICUs of Mubarak Hospital (ICU-1), the Kuwait Cancer Control Centre (ICU-2), and the BU of Ibn Sina Hospital. The presence of C. difficile and/or its toxin was detected by serially culturing the specimens on differential, selective and enriched media and the use of TOX-A/B test, on admission and at subsequent 1-weekly interval until discharge. RESULTS: Out of the 344 patients admitted into these units, over a study period of 1 year, only 263 (77%) were evaluable. All of them had negative stool culture/toxin on admission. Overall, 25 (9.5%) of these 263 patients acquired C. difficile during their hospitalization. Thirteen (7%) of 187 patients acquired C. difficile in ICU-1, 9 (36%) of 25 on ICU-2 and 3 (5.9%) of 51 patients in BU. Eight (32%) developed diarrhoea attributable only to C. difficile and/or toxin, and the remaining 17 (68%) were asymptomatic: none had pseudomembranous colitis. The diarrhoea in these patients was associated with antibiotic use, the main trigger-antibiotics being the third-generation cephalosporins. Acquisition occurred within 4-53 days of admission, with the majority occurring in the first 15 days. CONCLUSION: Overall, the prevalence of hospital-acquired C. difficile infection/colonization was less than 10%. The use of third-generation cephalosporins was high and was related to the development of diarrhoea. Once acquired, diarrhoea developed in about one third of C. difficile-positive cases, an indication that C. difficile infection/colonization endemic in the hospital ICUs studied is usually transmitted among the hospitalized patients.

Adolescent↗

PubMed2000

Polymeric IgA is superior to monomeric IgA and IgG carrying the same variable domain in preventing Clostridium difficile toxin A damaging of T84 monolayers.

The two exotoxins A and B produced by Clostridium difficile are responsible for antibiotic-associated enterocolitis in human and animals. When added apically to human colonic carcinoma-derived T84 cell monolayers, toxin A, but not toxin B, abolished the transepithelial electrical resistance and altered the morphological integrity. Apical addition of suboptimal concentration of toxin A made the cell monolayer sensitive to toxin B. Both toxins induced drastic and rapid epithelial alterations when applied basolaterally with a complete disorganization of tight junctions and vacuolization of the cells. Toxin A-specific IgG2a from hybridoma PCG-4 added apically with toxin A alone or in combination with toxin B abolished the toxin-induced epithelial alterations for up to 8 h. The Ab neutralized basolateral toxin A for 4 h, but not the mixture of the two toxins. Using an identical Ab:Ag ratio, we found that recombinant polymeric IgA (IgAd/p) with the same Fv fragments extended protection against toxin A for at least 24 h in both compartments. In contrast, the recombinant monomeric IgA counterpart behaved as the PCG-4 IgG2a Ab. The direct comparison between different Ig isotype and molecular forms, but of unique specificity, demonstrates that IgAd/p Ab is more efficient in neutralizing toxin A than monomeric IgG and IgA. We conclude that immune protection against C. difficile toxins requires toxin A-specific secretory Abs in the intestinal lumen and IgAd/p specific for both toxins in the lamina propria.

Antibody Specificity↗

PubMed1998

Hospital-wide restriction of clindamycin: effect on the incidence of Clostridium difficile-associated diarrhea and cost.

BACKGROUND: Widespread antibiotic use has been associated with increases in both bacterial resistance and nosocomial infection. OBJECTIVE: To characterize the impact of hospital-wide clindamycin restriction on the incidence of Clostridium difficile-associated diarrhea and on antimicrobial prescribing practices. DESIGN: Prospective, observational cohort study. SETTING: University-affiliated Veterans Affairs Medical Center. PATIENTS: Hospitalized patients with symptomatic diarrhea. MEASUREMENTS: Clinical data on individual patients and data on antibiotic use were obtained from hospital pharmacy records. Hospital-wide use of antimicrobial agents was monitored. Isolates of C. difficile underwent antimicrobial susceptibility testing and molecular typing. RESULTS: An outbreak of C. difficile-associated diarrhea was caused by a clonal isolate of clindamycin-resistant C. difficile and was associated with increased use of clindamycin. Hospital-wide requirement of approval by an infectious disease consultant of clindamycin use led to an overall reduction in clindamycin use, a sustained reduction in the mean number of cases of C. difficile-associated diarrhea (11.5 cases/month compared with 3.33 cases/month; P < 0.001), and an increase in clindamycin susceptibility among C. difficile isolates (9% compared with 61%; P < 0.001). A parallel increase was noted in the use of and costs associated with other antibiotics with antianaerobic activity, including cefotetan, ticarcillin-clavulanate, and imipenem-cilastin. The hospital realized overall cost savings as a result of the decreased incidence of C. difficile-associated diarrhea. CONCLUSIONS: Hospital formulary restriction of clindamycin is an effective way to decrease the number of infections due to C. difficile. It can also lead to a return in clindamycin susceptibility among isolates and can effect cost savings to the hospital.

Anti-Bacterial Agents↗

PubMed2003

[Assessment of susceptibility to metronidazole and vancomycin of Clostridium difficile strains isolated between 1998-2002].

The drugs of choice used to treat C. diffcile associated diarrhoea (CDAD) are metronidazole and vancomycin. C. difficile strains isolated in most laboratories are susceptible to metronidazole and vancomycin. Communication about emergence of antimicrobial resistance among C. difficile strains in some countries to metronidazole and intermediate resistance to vancomycin are alarming. This study was performed to determine the susceptibility to metronidazole and vancomycin of 140 C. difficile strains isolated from patients with CDAD hospitalised in academic hospital between 1999-2002. Resistance to metronidazole and vancomycin was not observed.

Anti-Bacterial Agents↗

PubMed1990

An extracellular material observed in Clostridium difficile strains.

Some extracellular material-- "capsule" has been observed among Clostridium difficile strains. C. difficile strains (44 examined) contain different proportions of cells with "capsule" and without "capsules". Toxigenic strains contained fewer capsulated cells than non-toxigenic strains.

Bacterial Proteins↗