Clostridium difficile: clinical disease and diagnosis

Hand contamination and hand hygiene knowledge and practices among commercial transport users after the SARS-CoV-2 virus (COVID-19) scare, Enugu State, Nigeria

Contaminated hands are one of the most common modes of microorganism transmission that are responsible for many associated infections in healthcare, food industries, and public places such as transportation parks. Public health approaches during COVID-19 pandemic have shown that hand hygiene practices and associated knowledge are critical measure to control the spread of infectious agent. Hence, assessment of commercial transport users' knowledge, belief and practices on hand hygiene, and potential contamination with infectious agents which is the aim of the study, aligns with general health concern of quantifying contamination risk levels to predict disease outbreaks. This study utilized a randomized sampling approach to select 10 frequently used commercial parks within two districts in the State: Enugu and Nsukka. The parameters analysed include a cross-sectional questionnaire survey, hand swab and hand washed samples collected from dominant hand of participants. A total of 600 participants responded to the questionnaire survey, while 100 participants' hand swabs were examined for microbial contamination. This study recorded a high prevalence of fungal (90.0%) and bacterial (87.0%) species; 20 species of fungus were identified with prevalence range of 1% to 14%; 21 bacterial species were isolated with prevalence range of 1% to 16%. These species were identified as either opportunistic, non-invasive, or pathogenic, which may constitute a health concern amongst immunocompromised individuals within the population. Aspergillus spp. (14%), was the most common fungal species that was exclusively found amongst Nsukka commercial users, while E. coli was the most prevalent isolated bacterial species amongst Nsukka (12%) and Enugu (20%) commercial park users. Prevalence of fungal contamination in Nsukka (94.0%; 47/50) and Enugu (86.0%; 43/50) were both high. Prevalence of bacterial contamination was higher in Enugu than Nsukka but not significantly (47[94.0%] vs. 40[80.0%], p = 0.583). A greater number of participants (99.3%) were aware of the importance of hand hygiene, however with low compliance rate aside "after using the toilet" (80%) and "before eating" (90%), other relevant hand washing and sanitizing practices were considered less important. With these observations, we can emphatically say that despite the COVID-19 scare, commercial park users within the sampled population do not efficiently practice quality hand wash and hygiene measures, hence, risking the widespread of infectious agents in situation of disease outbreak or among immunocompromised individuals.

Host Immunity and Immunization Strategies for Clostridioides difficile Infection

Clostridioides difficile infection (CDI) represents a significant challenge to public health. C. difficile-associated mortality and morbidity have led the U.S. CDC to designate it as an urgent threat. Moreover, recurrence or relapses can occur in up to a third of CDI patients, due in part to antibiotics being the primary treatment for CDI and the major cause of the disease. In this review, we summarize the current knowledge of innate immune responses, adaptive immune responses, and the link between innate and adaptive immune responses of the host against CDI. The other major determinants of CDI, such as C. difficile toxins, the host microbiota, and related treatments, are also described. Finally, we discuss the known therapeutic approaches and the current status of immunization strategies for CDI, which might help to bridge the knowledge gap in the generation of therapy against CDI.

Drug-induced bowel complications and toxicities: imaging findings and pearls

The use of diverse types of drugs can result in a variety of acute and chronic complications that affect almost any organ. The bowel is one of the organs impacted by the side effects of medications. Imaging frequently plays a crucial role in the detection and characterization of complications occurring in the bowel. They include pseudomembranous colitis or antibiotic-associated colitis; angioedema induced by angiotensin-converting enzyme inhibitors; nonsteroidal anti-inflammatory drug-induced enteropathy; cocaine toxicity; clozapine-induced hypomobility; and bowel toxicity induced by chemotherapeutic agents. It is imperative that radiologists are fully aware of these complications and toxicities as well as the relevant findings. In this way, proper treatment can be implemented immediately. The treatment will involve discontinuation of a drug or a change in regimen.

European Society of Clinical Microbiology and Infectious Diseases: 2021 update on the treatment guidance document for Clostridioides difficile infection in adults

SCOPE

In 2009, the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) published the first treatment guidance document for Clostridioides difficile infection (CDI). This document was updated in 2014. The growing literature on CDI antimicrobial treatment and novel treatment approaches, such as faecal microbiota transplantation (FMT) and toxin-binding monoclonal antibodies, prompted the ESCMID study group on C. difficile (ESGCD) to update the 2014 treatment guidance document for CDI in adults.

METHODS AND QUESTIONS

Key questions on CDI treatment were formulated by the guideline committee and included: What is the best treatment for initial, severe, severe-complicated, refractory, recurrent and multiple recurrent CDI? What is the best treatment when no oral therapy is possible? Can prognostic factors identify patients at risk for severe and recurrent CDI and is there a place for CDI prophylaxis? Outcome measures for treatment strategy were: clinical cure, recurrence and sustained cure. For studies on surgical interventions and severe-complicated CDI the outcome was mortality. Appraisal of available literature and drafting of recommendations was performed by the guideline drafting group. The total body of evidence for the recommendations on CDI treatment consists of the literature described in the previous guidelines, supplemented with a systematic literature search on randomized clinical trials and observational studies from 2012 and onwards. The Grades of Recommendation Assessment, Development and Evaluation (GRADE) system was used to grade the strength of our recommendations and the quality of the evidence. The guideline committee was invited to comment on the recommendations. The guideline draft was sent to external experts and a patients' representative for review. Full ESCMID endorsement was obtained after a public consultation procedure.

RECOMMENDATIONS

Important changes compared with previous guideline include but are not limited to: metronidazole is no longer recommended for treatment of CDI when fidaxomicin or vancomycin are available, fidaxomicin is the preferred agent for treatment of initial CDI and the first recurrence of CDI when available and feasible, FMT or bezlotoxumab in addition to standard of care antibiotics (SoC) are preferred for treatment of a second or further recurrence of CDI, bezlotoxumab in addition to SoC is recommended for the first recurrence of CDI when fidaxomicin was used to manage the initial CDI episode, and bezlotoxumab is considered as an ancillary treatment to vancomycin for a CDI episode with high risk of recurrence when fidaxomicin is not available. Contrary to the previous guideline, in the current guideline emphasis is placed on risk for recurrence as a factor that determines treatment strategy for the individual patient, rather than the disease severity.

Fecal Microbiota Transplantation May Be the Best Option in Treating Multiple Clostridioides difficile Infection: A Network Meta-Analysis

Introduction

Clostridioides difficile (formerly Clostridium) infection (CDI) is the most common cause of healthcare-associated diarrhea with high mortality and recurrence rate; furthermore, the treatment of recurrent cases is a challenge. In this network meta-analysis, we aimed to compare all available therapies against multiple recurrent CDI (mrCDI) and rank them by efficacy.

Methods

After a systematic search, randomized controlled trials (RCT) with any interventions against mrCDI were included. Data were extracted to the study database using Excel. Risk of bias assessment was performed with the Cochrane RoB 2 tool. The primary outcome was the clinical cure of CDI and the secondary outcome was the recurrence of CDI. A Bayesian method was performed to investigate the efficacy rank order of therapies. We registered our protocol with the Prospero Center for Reviews and Dissemination (registration no. CRD42020160365).

Results

Six RCTs with seven interventions were included in the quantitative synthesis. According to the surface under the cumulative ranking curve values, fecal microbiota transplantation (FMT) after a short course of vancomycin therapy (83%) shows the highest efficacy for clinical cure. Tolevamer and vancomycin + FMT seemed to be the most effective in preventing recurrence (87% and 75%, respectively).

Conclusion

Vancomycin + FMT is perhaps the most effective option for the treatment and prevention of mrCDI, while tolevamer is also effective in preventing recurrence.

Electronic Supplementary Material

The online version of this article (10.1007/s40121-020-00356-9) contains supplementary material, which is available to authorized users.

Mixed Viral-Bacterial Infections and Their Effects on Gut Microbiota and Clinical Illnesses in Children

Acute gastroenteritis remains a major cause of morbidity and mortality among young children worldwide. It accounts for approximately 1.34 million deaths annually in children younger than five years. Infection can be caused by viral, bacterial and/or parasitic microorganisms. Dysbiosis due to such infections could dramatically affect disease prognosis as well as development of chronic illness. The aim of this study was to analyze gut microbiome and clinical outcomes in young children suffering from viral or mixed viral-bacterial infection. We evaluated gut microbiota composition in children suffering from viral or mixed viral-bacterial infection with two major viruses rotavirus (RV) and norovirus (NoV) and two pathogenic bacteria [Enteroaggregative E. coli (EAEC), and Enteropathogenic E. coli (EPEC)]. We sequenced 16S ribosomal RNA (V4 region) genes using Illumina MiSeq in 70 hospitalized children suffering from gastroenteric infections plus nine healthy controls. The study summarized Operational Taxonomic Unit (OTU) abundances with the Bray-Curtis index and performed a non-metric multidimensional scaling analysis to visualize microbiome similarities. We used a permutational multivariate analyses of variance to test the significance of group differences. We also analyzed the correlation between microbiome changes and clinical outcomes. Our data demonstrated a significant increase in the severity score in children with viral-bacterial mixed infections compared to those with virus infections alone. Statistical analysis by overall relative abundance denoted lesser proportions of Bacteroides in the infected children, whereas Bifidobacteriaceae richness was more prominent in the bacterial-viral mixed infections. Pairwise differences of gut microbiota were significantly higher in RV + EAEC (P = 0.009) and NoV + EAEC (P = 0.009) co-infections, compared to EPEC mixed infection with both, RV (P = 0.045) and NoV (P = 0.188). Shannon diversity index showed considerable more variation in microbiome diversity in children infected with RV cohort compared to NoV cohort. Our results highlight that richness of Bifidobacteriaceae, which acts as probiotics, increased with the severity of the viral-bacterial mixed infections. As expected, significant reduction of relative numbers of Bacteroides was characterized in both RV and NoV infections, with more reduction observed in co-infection pathogenic E. coli. Although mixed infection with EAEC resulted in significant microbiota differences compared to viral infection only or mixed infection with EPEC, the clinical condition of the children were worsened with both pathogenic E.coli co-infections. Further, in comparison with RV cohort, augmented number of differential abundant pathogenic OTUs were peculiarly noticed only with NoV mixed infection.

The Gut Microbiome in Multiple Sclerosis: A Potential Therapeutic Avenue

Recently, there has been a substantial increase in the number of studies focused upon connecting the gut microbiome with cases of central nervous system (CNS) autoimmunity. Multiple sclerosis (MS) is a neurodegenerative autoimmune disorder of the CNS. Recent experimental and clinical evidence suggests the presence of microbial imbalances in the gut of MS sufferers. The gut microbiome is defined as the summation of all the microbial entities as well as their genes, proteins, and metabolic products in a given space and time. Studies show the MS gut microbiome as having general alterations in specific taxa, some associated with the promotion of inflammatory cytokines and overall inflammation. In conjunction with these findings, experimental models of the disease have reported that T regulatory (Treg) cells have deficits in their function as a result of the aberrant gut microbiota composition. The findings suggest that the interactions between the host and the microbiota are reciprocal, although more extensive work is required to confirm this. Moreover, evidence indicates that changes in microbiota composition may result in imbalances that could result in disease, with the gut as a potential novel therapeutic avenue. By understanding the biological effects of aberrant gut microbiome composition, it is possible to contemplate current therapeutic options and their efficacy. Ultimately, more research is necessary in this field, but targeting the gut microbiota may lead to the development of novel therapeutic strategies.

Potential of real-time PCR threshold cycle (CT) to predict presence of free toxin and clinically relevant C. difficile infection (CDI) in patients with cancer

OBJECTIVES

Clostridium difficile infection (CDI) is a toxin-mediated disease. Oncology patients are at increased risk for developing CDI. Diagnosis of CDI by PCR has led to misclassification of some C. difficile carriers as CDI cases. We determined if an optimized C. difficile PCR cycle threshold value (C_T) could reliably predict presence of free toxin, and in turn improve the utility of PCR in detecting clinically relevant CDI in oncology patients.

METHODS

183 consecutive patients positive for C. difficile by the Xpert C. difficile were additionally tested using the cell culture cytotoxicity neutralization assay (CYT) and enzyme immunoassays (EIA). C_T values at diagnosis and relevant clinical information were recorded. Receiver operating characteristic (ROC) curve was used to assess predictive validity and to find optimal C_T for CYT positive cases. Severity of CDI was assessed by blinded charts review.

RESULTS

Using CYT as the reference, ROC-derived Youden cut-off C_T of 28.0 predicted 77% cytotoxin positive cases, and 91% and 100% of severe and complicated CDI episodes respectively. The median C_T values for non-severe, severe, and complicated CDI episodes were 28.0, 24.5 and 22.5 respectively (p = 0.005).

CONCLUSIONS

Lower C_T value of the Xpert C. difficile PCR was associated with the presence of toxin and increased CDI severity. C_T values may be beneficial in interpreting positive C. difficile PCR results.

A review on laboratory tests' utilization: A trigger for cutting costs and quality improvement in health care settings

BACKGROUND

Considering the role of laboratory tests as a central part of controlling health expenditure, this study intends to investigate laboratory tests overutilization in Iran to pave the way for future interventions.

METHODS

Inappropriate laboratory utilization was reviewed in a cross-sectional survey through the retrospective analysis of 384 medical records at a tertiary center. To pave the way for future intervention, overutilization tests were classified into two categories, inappropriate and inefficient, and then they were analyzed. Frequency analysis was used to analysis patient's age, gender, hospital wards, length of stay, and diagnosis as well as inappropriate test and inefficient tests.

RESULTS

A total of 143 (1.50 %) of the tests were inefficient and was ordered due to laboratory errors including hemolysis, inefficient sampling, or absurd results. 2522 (26.40%) of the tests were inappropriate and stem from failure to meet medical/clinical appropriateness criteria.

CONCLUSION

Whereas, inappropriate test ordering was more frequent than inefficient tests, the initial improvement strategy should focus on physicians' test ordering behavior through conducting proper teaching strategies, ongoing audit and educational feedback, implementing health information technology tools and employing laboratory practice guidelines (LPGs) and testing algorithms. Conducting continuous quality improvement cycle for laboratory services and training of personnel involved in blood sampling is recommended for inefficient tests.

Biochemical and Immunological Characterization of Truncated Fragments of the Receptor-Binding Domains of C. difficile Toxin A

Clostridium difficile is an emerging pathogen responsible for opportunistic infections in hospitals worldwide and is the main cause of antibiotic-associated pseudo-membranous colitis and diarrhea in humans. Clostridial toxins A and B (TcdA and TcdB) specifically bind to unknown glycoprotein(s) on the surface of epithelial cells in the host intestine, disrupting the intestinal barrier and ultimately leading to acute inflammation and diarrhea. The C-terminal receptor-binding domain (RBD) of TcdA, which is responsible for the initial binding of the toxin to host glycoproteins, has been predicted to contain 7 potential oligosaccharide-binding sites. To study the specific roles and functions of these 7 putative lectin-like binding regions, a consensus sequence of TcdA RBD derived from different C. difficile strains deposited in the NCBI protein database and three truncated fragments corresponding to the N-terminal (residues 1–411), middle (residues 296–701), and C-terminal portions (residues 524–911) of the RBD (F1, F2 and F3, respectively) were designed and expressed in Escherichia coli. In this study, the recombinant RBD (rRBD) and its truncated fragments were purified, characterized biologically and found to have the following similar properties: (a) are capable of binding to the cell surface of both Vero and Caco-2 cells; (b) possess Toll-like receptor agonist-like adjuvant activities that can activate dendritic cell maturation and increase the secretion of pro-inflammatory cytokines; and (c) function as potent adjuvants in the intramuscular immunization route to enhance immune responses against weak immunogens. Although F1, F2 and F3 have similar repetitive amino acid sequences and putative oligosaccharide-binding domains, they do not possess the same biological and immunological properties: (i) TcdA rRBD and its fragments bind to the cell surface, but only TcdA rRBD and F3 internalize into Vero cells within 15 min; (ii) the fragments exhibit various levels of hemagglutinin (HA) activity, with the exception of the F1 fragment, which demonstrates no HA activity; and (iii) in the presence of alum, all fragments elicit various levels of anti-toxin A-neutralizing antibody responses, but those neutralizing antibodies elicited by F2 did not protect mice against a TcdA challenge. Because TcdA rRBD, F1 and F3 formulated with alum can elicit immune protective responses against the cytotoxicity of TcdA, they represent potential components of future candidate vaccines against C. difficile-associated diseases.

Recombinant lipoprotein-based vaccine candidates against C. difficile infections

Background

Opportunistically nosocomial infections in hospitalized patients are often related to Clostridium difficile infections (CDI) due to disruption of the intestinal micro-flora by antibiotic therapies during hospitalization. Clostridial exotoxins A and B (TcdA and TcdB) specifically bind to unknown glycoprotein(s) in the host intestine, disrupt the intestinal barrier leading to acute inflammation and diarrhea. The C-terminal receptor binding domain of TcdA (A-rRBD) has been shown to elicit antibody responses that neutralize TcdA toxicity in Vero cell cytotoxicity assays, but not effectively protect hamsters against a lethal dose challenge of C. difficile spores. To develop an effective recombinant subunit vaccine against CDI, A-rRBD was lipidated (rlipoA-RBD) as a rational design to contain an intrinsic adjuvant, a toll-like receptor 2 agonist and expressed in Escherichia coli.

Results

The purified rlipoA-RBD was characterized immunologically and found to have the following properties: (a) mice, hamsters and rabbits vaccinated with 3 μg of rlipoA-RBD produced strong antibody responses that neutralized TcdA toxicity in Vero cell cytotoxicity assays; furthermore, the neutralization titer was comparable to those obtained from antisera immunized either with 10 μg of TcdA toxoid or 30 μg of A-rRBD; (b) rlipoA-RBD elicited immune responses and protected mice from TcdA challenge, but offered insignificant protection (10 to 20 %) against C. difficile spores challenge in hamster models; (c) only rlipoA-RBD formulated with B-rRBD consistently confers protection (90 to 100 %) in the hamster challenge model; and (d) rlipoA-RBD was found to be 10-fold more potent than A-rRBD as an adjuvant to enhancing immune responses against a poor antigen such as ovalbumin.

Conclusion

These results indicate that rlipoA-RBD formulated with B-rRBD could be an excellent vaccine candidate for preclinical studies and future clinical trials.

European Society of Clinical Microbiology and Infectious Diseases: update of the treatment guidance document for Clostridium difficile infection

In 2009 the first European Society of Clinical Microbiology and Infection (ESCMID) treatment guidance document for Clostridium difficile infection (CDI) was published. The guideline has been applied widely in clinical practice. In this document an update and review on the comparative effectiveness of the currently available treatment modalities of CDI is given, thereby providing evidence-based recommendations on this issue. A computerized literature search was carried out to investigate randomized and non-randomized trials investigating the effect of an intervention on the clinical outcome of CDI. The Grades of Recommendation Assessment, Development and Evaluation (GRADE) system was used to grade the strength of our recommendations and the quality of the evidence. The ESCMID and an international team of experts from 11 European countries supported the process. To improve clinical guidance in the treatment of CDI, recommendations are specified for various patient groups, e.g. initial non-severe disease, severe CDI, first recurrence or risk for recurrent disease, multiple recurrences and treatment of CDI when oral administration is not possible. Treatment options that are reviewed include: antibiotics, toxin-binding resins and polymers, immunotherapy, probiotics, and faecal or bacterial intestinal transplantation. Except for very mild CDI that is clearly induced by antibiotic usage antibiotic treatment is advised. The main antibiotics that are recommended are metronidazole, vancomycin and fidaxomicin. Faecal transplantation is strongly recommended for multiple recurrent CDI. In case of perforation of the colon and/or systemic inflammation and deteriorating clinical condition despite antibiotic therapy, total abdominal colectomy or diverting loop ileostomy combined with colonic lavage is recommended.

Molecular epidemiology of Clostridium difficile at a medical center in Taiwan: persistence of genetically clustering of A⁻B⁺ isolates and increase of A⁺B⁺ isolates

Introduction

We 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.

Methods

A 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.

Results

Among 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.

Conclusions

This 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.

A Lactobacillus casei Shirota probiotic drink reduces antibiotic-associated diarrhoea in patients with spinal cord injuries: a randomised controlled trial

Certain probiotics may prevent the development of antibiotic-associated diarrhoea (AAD) and Clostridium difficile-associated diarrhoea (CDAD), but their effectiveness depends on both strain and dose. There are few data on nutritional interventions to control AAD/CDAD in the spinal cord injury (SCI) population. The present study aimed to assess (1) the efficacy of consuming a commercially produced probiotic containing at least 6·5 × 10⁹ live Lactobacillus casei Shirota (LcS) in reducing the incidence of AAD/CDAD, and (2) whether undernutrition and proton pump inhibitors (PPI) are risk factors for AAD/CDAD. A total of 164 SCI patients (50·1 (sd 17·8) years) with a requirement for antibiotics (median 21 d, range 5-366) were randomly allocated to receive LcS (n 76) or no probiotic (n 82). LcS was given once daily for the duration of the antibiotic course and continued for 7 days thereafter. Nutritional risk was assessed by the Spinal Nutrition Screening Tool. The LcS group had a significantly lower incidence of AAD (17·1 v. 54·9%, P< 0·001). At baseline, 65% of patients were at undernutrition risk. Undernutrition (64·1 v. 33·3%, P< 0·01) and the use of PPI (38·4 v. 12·1 %, P= 0·022) were found to be associated with AAD. However, no significant difference was observed in nutrient intake between the groups. The multivariate logistic regression analysis identified poor appetite ( < 1/2 meals eaten) (OR 5·04, 95% CI 1·28, 19·84) and no probiotic (OR 8·46, 95% CI 3·22, 22·20) as the independent risk factors for AAD. The present study indicated that LcS could reduce the incidence of AAD in hospitalised SCI patients. A randomised, placebo-controlled study is needed to confirm this apparent therapeutic success in order to translate into improved clinical outcomes.

Immunological evaluation of a synthetic Clostridium difficile oligosaccharide conjugate vaccine candidate and identification of a minimal epitope

Clostridium difficile is the cause of emerging nosocomial infections that result in abundant morbidity and mortality worldwide. Thus, the development of a vaccine to kill the bacteria to prevent this disease is highly desirable. Several recently identified bacterial surface glycans, such as PS-I and PS-II, are promising vaccine candidates to preclude C. difficile infection. To circumvent difficulties with the generation of natural PS-I due to its low expression levels in bacterial cultures, improved chemical synthesis protocols for the pentasaccharide repeating unit of PS-I and oligosaccharide substructures were utilized to produce large quantities of well-defined PS-I related glycans. The analysis of stool and serum samples obtained from C. difficile patients using glycan microarrays of synthetic oligosaccharide epitopes revealed humoral immune responses to the PS-I related glycan epitopes. Two different vaccine candidates were evaluated in the mouse model. A synthetic PS-I repeating unit CRM197 conjugate was immunogenic in mice and induced immunoglobulin class switching as well as affinity maturation. Microarray screening employing PS-I repeating unit substructures revealed the disaccharide Rha-(1→3)-Glc as a minimal epitope. A CRM197-Rha-(1→3)-Glc disaccharide conjugate was able to elicit antibodies recognizing the C. difficile PS-I pentasaccharide. We herein demonstrate that glycan microarrays exposing defined oligosaccharide epitopes help to determine the minimal immunogenic epitopes of complex oligosaccharide antigens. The synthetic PS-I pentasaccharide repeating unit as well as the Rha-(1→3)-Glc disaccharide are promising novel vaccine candidates against C. difficile that are currently in preclinical evaluation.

Clostridium difficile PSI polysaccharide: synthesis of pentasaccharide repeating block, conjugation to exotoxin B subunit, and detection of natural anti-PSI IgG antibodies in horse serum

Clostridium difficile is the most common cause of antimicrobial-associated diarrhea in humans and may cause death. Previously, we discovered that C. difficile expresses three polysaccharides, named PSI, PSII, and PSIII. It has now been established that PSII is a conserved antigen abundantly present on the cell-surface and biofilm of C. difficile. In contrast, the expression of PSI and PSIII appears to be stochastic processes. In this work, the total chemical synthesis of the PSI pentasaccharide repeating unit carrying a linker at the reducing end, α-l-Rhap-(1→3)-β-d-Glcp-(1→4)-[α-l-Rhap-(1→3)]-α-d-Glcp-(1→2)-α-d-Glcp-(1→O(CH2)5NH2, was achieved by a linear synthesis strategy from four monosaccharide building blocks. The synthesized PSI pentasaccharide was conjugated to a subunit of C. difficile exotoxin B yielding a potential dual C. difficile vaccine. More significantly, sera from healthy horses were shown to contain natural anti-PSI IgG antibodies that detected both the synthetic non-phosphorylated PSI repeat and the native PSI polysaccharide, with a slightly higher recognition of the native PSI polysaccharide.

Diarrhea recurrence in patients with Clostridium difficile-associated diarrhea: Role of concurrent antibiotics

OBJECTIVE

To monitor prospectively patients with Clostridium difficile-associated diarrhea (CAD) in a six hundred bed tertiary care hospital to determine which factors influenced the recurrence of the diarrhea.

DESIGN

A prospective, nonrandomized study. After an initial diagnosis of CAD, patients were interviewed, and each week stool samples and environmental samples were monitored for the presence of toxigenic C difficile for as long as the patients remained in hospital. The relationship of concurrent antibiotics, prolonged fecal excretion of organism or toxin, and environmental contamination was assessed.

PATIENTS

Over a two-and-a-half year period, 75 consecutive patients with CAD were selected and those who gave their written informed consent were enrolled. A control group to evaluate environmental contamination consisted of 75 patients with diarrhea not associated with C difficile.

RESULTS

Of the 75 CAD patients, 11 (14.7%) had a recurrence of their diarrhea. Diarrhea recurrence was associated with an increased rate of prolonged excretion of toxigenic organism and/or C difficile toxin(s) (nine of 11 [81.8%] compared with nine of 64 [14.1%]; P≤0.0001; relative risk 14.25; 95% CI 3.383 to 60.023). The risk of diarrhea recurrence was not related to a specific antibiotic but to concurrent therapy. Treatment within 30 days of initial CAD-specific treatment with an antibiotic other than metronidazole or vancomycin occurred significantly more frequently in patients with recurrence of diarrhea compared with those who did not have a recurrence (eight of 11 [72.7%] compared with 22 of 64 [34.4%], P=0.022; relative risk 4; 95% CI 1.153 to 13.881). The environmental contamination rate for toxigenic C difficile in week one in the rooms of patients with diarrhea not caused by C difficile was low (two of 75 [2.6%]) compared with week one data for patients with CAD (14 of 75 [18.7%], P=0.002; relative risk 1.922; 95% CI 1.479 to 2.498). The most frequent site contaminated was the bedpan sprayer (eight of 14 [57.1%]). Pulsed field gel electrophoresis analysis of stool and environmental toxigenic isolates indicated that there was not a single endemic strain of C difficile.

CONCLUSIONS

This study indicates that the recurrence of diarrhea may be related to concurrent 'other' antibiotics. Although data indicated that there was a correlation between diarrhea recurrence and prolonged fecal excretion of toxin, further studies are required to clarify the clinical significance.

Phosphorylation of the synthetic hexasaccharide repeating unit is essential for the induction of antibodies to Clostridium difficile PSII cell wall polysaccharide

Clostridium difficile is emerging worldwide as a major cause of nosocomial infections. The negatively charged PSII polysaccharide has been found in different strains of C. difficile and, thereby, represents an important target molecule for a possible carbohydrate-based vaccine. In order to identify a synthetic fragment that after conjugation to a protein carrier could be able to induce anti-PSII antibodies, we exploited a combination of chemical synthesis with immunochemistry, confocal immunofluorescence microscopy, and solid state NMR. We demonstrate that the phosphate group is crucial in synthetic glycans to mimic the native PSII polysaccharide; both native PSII and a phosphorylated synthetic hexasaccharide repeating unit conjugated to CRM(197) elicit comparable immunogenic responses in mice. This finding can aid design and selection of carbohydrate antigens to be explored as vaccine candidates.

Induction of cytokines in a macrophage cell line by proteins of Clostridium difficile

Clostridium difficile is a major cause of nosocomial diarrhoea. The toxins produced by C. difficile are responsible for the characteristic pathology observed in C. difficile disease, but several surface-associated proteins of C. difficile are also recognized by the immune system and could modulate the immune response in infection. The aim of this study was to assess the induction of cytokines in a macrophage cell line in response to different antigens prepared from five C. difficile strains: the hypervirulent ribotype 027, ribotypes 001 and 106 and reference strains VPI 10463 and 630 (ribotype 012). PMA-activated THP-1 cells were challenged with surface-layer proteins, flagella, heat-shock proteins induced at 42 and 60 °C and culture supernatants of the five C. difficile strains. The production of the pro-inflammatory cytokines such as TNF-α, IL-1β, IL-6, IL-8 and IL-12p70 was observed in response to the surface-associated proteins, and high levels of TNF-α, IL-1β and IL-8 were detected in response to challenge with culture supernatants. The immune response triggered by the surface-associated proteins was independent of the strain from which the antigens were derived, suggesting that these proteins might not be related to the varying virulence of the hypervirulent ribotype 027 or ribotypes 001 and 106. There was no interstrain difference observed in response to the culture supernatants of the tested C. difficile strains, but this was perhaps due to toxicity induced in the macrophages by large amounts of toxin A and toxin B.

Structural characterization of surface glycans from Clostridium difficile

Whole-cell high-resolution magic angle spinning (HR-MAS) NMR was employed to survey the surface polysaccharides of a group of clinical and environmental isolates of Clostridium difficile. Results indicated that a highly conserved surface polysaccharide profile among all strains studied. Multiple additional peaks in the anomeric region were also observed which prompted further investigation. Structural characterization of the isolated surface polysaccharides from two strains confirmed the presence of the conserved water soluble polysaccharide originally described by Ganeshapillai et al. which was composed of a hexaglycosyl phosphate repeat consisting of [→6)-β-D-Glcp-(1-3)-β-D-GalpNAc-(1-4)-α-D-Glcp-(1-4)-[β-D-Glcp(1-3]-β-D-GalpNAc-(1-3)-α-D-Manp-(1-P→]. In addition, analysis of phenol soluble polysaccharides revealed a similarly conserved lipoteichoic acid (LTA) which could be detected on whole cells by HR-MAS NMR. Conventional NMR and mass spectrometry analysis indicated that the structure of this LTA consisted of the repeat unit [→6)-α-D-GlcpNAc-(1-3)-[→P-6]-α-D-GlcpNAc-(1-2)-D-GroA] where GroA is glyceric acid. The repeating units were linked by a phosphodiester bridge between C-6 of the two GlcNAc residues (6-P-6). A minor component consisted of GlcpN-(1-3) instead of GlcpNAc-(1-3) in the repeat unit. Through a 6-6 phosphodiester bridge this polymer was linked to →6)-β-D-Glcp-(1-6)-β-D-Glcp-(1-6)-β-D-Glcp-(1-1)-Gro, with glycerol (Gro) substituted by fatty acids. This is the first report of the utility of HR-MAS NMR in the examination of surface carbohydrates of Gram positive bacteria and identification of a novel LTA structure from Clostridium difficile.

Progress toward developing a carbohydrate-conjugate vaccine against Clostridium difficile ribotype 027: synthesis of the cell-surface polysaccharide PS-I repeating unit

Clostridium difficile strain ribotype 027 is a hypervirulent pathogen that is responsible for recent, severe outbreaks of serious nosocomial infections. As a foundation for the development of a preventative carbohydrate-based vaccine, we have synthesized a pentasaccharide cell wall repeating unit from PS-I unique to this strain, by the linear assembly of four monosaccharide building blocks.

Super toxins from a super bug: structure and function of Clostridium difficile toxins

Clostridium difficile, a highly infectious bacterium, is the leading cause of antibiotic-associated pseudomembranous colitis. In 2009, the number of death certificates mentioning C. difficile infection in the U.K. was estimated at 3933 with 44% of certificates recording infection as the underlying cause of death. A number of virulence factors facilitate its pathogenicity, among which are two potent exotoxins; Toxins A and B. Both are large monoglucosyltransferases that catalyse the glucosylation, and hence inactivation, of Rho-GTPases (small regulatory proteins of the eukaryote actin cell cytoskeleton), leading to disorganization of the cytoskeleton and cell death. The roles of Toxins A and B in the context of C. difficile infection is unknown. In addition to these exotoxins, some strains of C. difficile produce an unrelated ADP-ribosylating binary toxin. This toxin consists of two independently produced components: an enzymatic component (CDTa) and the other, the transport component (CDTb) which facilitates translocation of CDTa into target cells. CDTa irreversibly ADP-ribosylates G-actin in target cells, which disrupts the F-actin:G-actin equilibrium leading to cell rounding and cell death. In the present review we provide a summary of the current structural understanding of these toxins and discuss how it may be used to identify potential targets for specific drug design.

First synthesis of C. difficile PS-II cell wall polysaccharide repeating unit

Clostridium difficile is the most commonly diagnosed cause of nosocomial diarrhea with increasing incidence and mortality among elderly and hospitalized patients. We report the first synthesis of the surface polysaccharide PS-II repeating unit and its nonphosphorylated analogue, with a linker for conjugation, via a (4 + 2) convergent approach from a common AB(D)C tetrasaccharide intermediate.

Proton pump inhibitors as a risk factor for paediatric Clostridium difficile infection

BACKGROUND

Proton pump inhibitors (PPIs) and H(2) receptor antagonists (H(2)RAs) may play an important role on the onset of Clostridium difficile-associated disease (CDAD) in adults. The impact of Clostridium difficile on children treated with gastric acid-suppressing agents remains unknown.

AIM

To investigate the relationship between CDAD and exposure to acid suppressive therapy in hospitalized paediatric patients.

METHODS

We reviewed the medical records of children, with a diagnosis of protracted diarrhoea and abdominal pain, whose stool was analysed for C. difficile toxins. We identified 68 patients with CDAD. For each patient, we randomly selected one control subjects with stool analysis negative for C. difficile. Comorbid illnesses, previous hospitalizations, antibiotics, corticosteroids, immunosuppressants and gastric acid suppressing exposures were recorded.

RESULTS

The use of PPI was significantly higher in C. difficile positive group compared with C. difficile negative group [odds ratio (OR): = 4.5; 95% confidence interval (CI) = 1.4-14.4]. We also found a trend for the use of H(2)RAs in patients infected by C. difficile compared with C. difficile negative comparison group (OR: = 3.8; 95% CI = 0.7-18.9).

CONCLUSIONS

Children exposed to PPIs therapy seem to be at higher risk for the development of Clostridium difficile-associated disease.

Structural basis for substrate recognition in the enzymatic component of ADP-ribosyltransferase toxin CDTa from Clostridium difficile

ADP-ribosylation is one of the favored modes of cell intoxication employed by several bacteria. Clostridium difficile is recognized to be an important nosocomial pathogen associated with considerable morbidity and attributable mortality. Along with its two well known toxins, Toxin A and Toxin B, it produces an ADP-ribosylating toxin that targets monomeric actin of the target cell. Like other Clostridial actin ADP-ribosylating toxins, this binary toxin, known as C. difficile toxin (CDT), is composed of two subunits, CDTa and CDTb. In this study, we present high resolution crystal structures of CDTa in its native form (at pH 4.0, 8.5, and 9.0) and in complex with ADP-ribose donors, NAD and NADPH (at pH 9.0). The crystal structures of the native protein show "pronounced conformational flexibility" confined to the active site region of the protein and "enhanced" disorder at low pH, whereas the complex structures highlight significant differences in "ligand specificity" compared with the enzymatic subunit of a close homologue, Clostridium perfringens iota toxin. Specifically in CDTa, two of the suggested catalytically important residues (Glu-385 and Glu-387) seem to play no role or a less important role in ligand binding. These structural data provide the first detailed information on protein-donor substrate complex stabilization in CDTa, which may have implications in understanding CDT recognition.

The management of Clostridium difficile infection

INTRODUCTION/BACKGROUND

Clostridium difficile is the commonest cause of nosocomial diarrhoea. The epidemiology and clinical phenotype of the disease has dramatically changed with the global emergence of a virulent strain of C. difficile.

SOURCE

This review was compiled using data from individual studies and review articles identified from PubMed. The retrieved articles were also examined for additional references.

AREAS OF AGREEMENT

Appropriate and timely infection control measures are required to control C. difficile infection (CDI) in the hospital environment, and either oral metronidazole or vancomycin remains the mainstay of treatment depending on the severity of infection.

AREAS OF CONTROVERSY

The optimal method for diagnosing CDI remains unclear, as does the best therapeutic strategy for the management of multiple relapses. GROWING POINTS/AREAS TIMELY FOR DEVELOPING RESEARCH: Studies of new antimicrobial agents with activity against C. difficile are required to improve the management of multiply relapsing disease. The use of novel therapeutic approaches that do not require antimicrobials requires urgent research, including the use of immunological or vaccine-based regimen, bacteriotherapy or C. difficile-specific bacteriophages.

Application of isothermal helicase-dependent amplification with a disposable detection device in a simple sensitive stool test for toxigenic Clostridium difficile

Enzyme immunoassays (EIAs) are commonly used for the diagnosis of cases of Clostridium difficile-associated diarrhea (CDAD). However, these EIAs have high false-negative rates, even in patients with severe clinical disease. We have developed an IsoAmp CDAD test using a simple and user-friendly procedure to identify toxigenic C. difficile in feces. After DNA extraction from fecal samples, both the conserved sequence of the 5'-end fragment of the C. difficile tcdA toxin gene and competitive amplification internal control sequence were amplified using helicase-dependent amplification. Amplification products were detected using a novel amplicon-containment detection device. The analytical sensitivity of the assay was 20 copies of C. difficile genomic DNA per reaction. Evaluation of the clinical sensitivity and specificity of the IsoAmp CDAD test versus an EIA method using a PCR method as the reference standard revealed 100% sensitivity and 100% specificity for the IsoAmp CDAD test compared with 90.9% sensitivity and 100% specificity for the EIA method. Because the IsoAmp CDAD test requires no expensive equipments for nucleic acid amplification or detection and can be performed on a random access basis, the test provides a practical alternative to immunoassays for the diagnosis of CDAD with improved sensitivity.

Clostridium difficile cell-surface polysaccharides composed of pentaglycosyl and hexaglycosyl phosphate repeating units

Clostridium difficile is a Gram-positive bacterium that is known to be a cause of enteric diseases in humans. It is the leading cause of antibiotic-associated diarrhea and pseudomembranous colitis. Recently, large outbreaks of C. difficile-associated diarrhea have been reported internationally, and there have been reports of increases in severe disease, mortality and relapse rates. At the moment, there is no vaccine against C. difficile, and the medical prevention of C. difficile infection is mostly based on the prophylactic use of antibiotics; however, this has led to an increase in the incidence of the disease. Here, we describe the chemical structure of C. difficile cell-surface polysaccharides. The polysaccharides of three C. difficile strains were structurally analyzed; ribotype 027 (North American pulsotype 1) strain was observed to express two polysaccharides, one was composed of a branched pentaglycosyl phosphate repeating unit: [-->4)-alpha-l-Rhap-(1-->3)-beta-D-Glcp-(1-->4)-[alpha-l-Rhap-(1-->3]-alpha-D-Glcp-(1-->2)-alpha-D-Glcp-(1-->P] and the other was composed of a hexaglycosyl phosphate repeating unit: [-->6)-beta-D-Glcp-(1-->3)-beta-D-GalpNAc-(1-->4)-alpha-D-Glcp-(1-->4)-[beta-D-Glcp-(1-->]-beta-D-GalpNAc-(1-->3)-alpha-D-Manp-(1-->P]. The latter polysaccharide was also observed to be produced by strains MOH900 and MOH718. The results described here represent the first literature report describing the covalent chemical structures of C. difficile cell-surface polysaccharides, of which PS-II appears to be a regular C. difficile antigen. These C. difficile teichoic-acid-like polysaccharides will be tested as immunogens in vaccine preparations in a rat and horse model.

Clostridium difficile-associated diarrhoea

Clostridium difficile is an important nosocomial pathogen and the most frequently diagnosed cause of infectious hospital-acquired diarrhoea. Toxigenic strains usually produce toxin A and toxin B, which are the primary virulence factors of C. difficile. Some recently described strains produce an additional toxin, an adenosine-diphosphate ribosyltransferase known as binary toxin, the role of which in pathogenicity is unknown. There has been concern about the emergence of a hypervirulent fluoroquinolone-resistant strain of C. difficile in North America and Europe. The use of fluoroquinolone antimicrobials appears to be acting as a selective pressure in the emergence of this strain. In this review, we describe the current state of knowledge about C. difficile as a cause of diarrhoeal illness.

The IStron CdISt1 of Clostridium difficile: molecular symbiosis of a group I intron and an insertion element

The IStron CdISt1 was first discovered as an insertion into the tcdA gene of the clinical isolate C34. It combines structural and functional properties of a group I intron at its 5'-end with those of an insertion element at its 3'-end. Up to date four different types could be found, mainly differing in their IS-element portions. Contrasting classical group I introns, CdISt1 is always integrated in ORFs encoding bacterial protein. In case CdISt1 had only the IS-element function such insertion would inactivate the protein encoded by the host gene. It is only due to the self-splicing activity of the group I intron parts that CdISt1 integration does not abolish protein function. Both elements seem to exist in molecular symbiosis and CdISt1 could thus be a prototype of a novel class of genetic elements. Moreover, integration of the CdISt1 into the genome could be advantageous for the bacterium, a motor function for evolution of bacterial proteins is discussed. In clinical practice CdISt1 might well serve as a tool for epidemiological studies of C. difficile infections.

Binary toxin producing Clostridium difficile strains

Clostridium difficile produces three toxins, TcdA, TcdB and CDT. TcdA and TcdB are single-stranded molecules acting as glucosyltransferases specific for small GTPases. CDT is an actin specific ADP-ribosylating binary toxin characteristically composed of two independent components, enzymatic CDTa (48 kDa) and binding CDTb (99 kDa). The cdtA and cdtB genes were sequenced in two CDT-positive strains of C. difficile (CD 196 and 8864) and at least two CDT-negative strains with truncated form of binary toxin genes are known (VPI 10463 and C. difficile genome strain 630). The prevalence of binary toxin producing strains is estimated to be from 1.6% to 5.5%, although a much higher proportion has been reported in some studies. The role of the binary toxin as an additional virulence factor is discussed.

Factors influencing the composition of the intestinal microbiota in early infancy

OBJECTIVE

The aim of this study was to examine the contribution of a broad range of external influences to the gut microbiotic composition in early infancy.

METHODS

Fecal samples from 1032 infants at 1 month of age, who were recruited from the KOALA Birth Cohort Study in the Netherlands, were subjected to quantitative real-time polymerase chain reaction assays for the enumeration of bifidobacteria, Escherichia coli, Clostridium difficile, Bacteroides fragilis group, lactobacilli, and total bacterial counts. Information on potential determinants of the gut microbiotic composition was collected with repeated questionnaires. The associations between these factors and the selected gut bacteria were analyzed with univariate and multivariate analyses.

RESULTS

Infants born through cesarean section had lower numbers of bifidobacteria and Bacteroides, whereas they were more often colonized with C difficile, compared with vaginally born infants. Exclusively formula-fed infants were more often colonized with E coli, C difficile, Bacteroides, and lactobacilli, compared with breastfed infants. Hospitalization and prematurity were associated with higher prevalence and counts of C difficile. Antibiotic use by the infant was associated with decreased numbers of bifidobacteria and Bacteroides. Infants with older siblings had slightly higher numbers of bifidobacteria, compared with infants without siblings.

CONCLUSIONS

The most important determinants of the gut microbiotic composition in infants were the mode of delivery, type of infant feeding, gestational age, infant hospitalization, and antibiotic use by the infant. Term infants who were born vaginally at home and were breastfed exclusively seemed to have the most "beneficial" gut microbiota (highest numbers of bifidobacteria and lowest numbers of C difficile and E coli).

Cytotoxicity and antimicrobial susceptibility of Clostridium difficile isolated from hospitalized children with acute diarrhea

Clostridium difficile is an important pathogen associated with outbreaks of pseudomembranous colitis and other intestinal disorders such as diarrhea. In this study, 181 stool samples from children with and without acute diarrhea were analysed. Eighteen children with acute diarrhea were positive to C. ramosum, C. difficile, C. limosum, C. clostridioforme, C. septicum, C. butyricum, C. innocuum and Clostridium sp. Nineteen children without diarrhea harbored C. ramosum, C. septicum, C. barattii, C. butyricum, C. innocuum, C. sphenoides, C. bifermentans, C. clostridioforme and C. paraputrificum. No patient with diarrhea harbored C. barattii, C. bifermentans, C. paraputrificum and C. sphenoides. In addition, ten C. difficile strains were detected in 5 (5.5%) of the children with diarrhea. Also, no children from control group harbored C. difficile, C. limosum and Clostridium sp. Most of the tested strains were resistant to all the used antimicrobial. Nine C. difficile were toxigenic on VERO cells and by multiplex PCR, six strains showed both toxin A and B genes and three strains showed only toxin B gene. In this study, the presence of C. difficile was not significant, and it is suggested the need of more studies to evaluate the role of clostridia or C. difficile play in the childhood diarrhea and these organisms must be looked for routinely and a periodic evaluation of antimicrobial susceptibility should be performed.

Antimicrobial susceptibility of Clostridium difficile isolated from neonatal pigs with enteritis

The minimum inhibitory concentration (MIC) of eight antimicrobial agents was determined by the agar dilution method for 80 isolates of Clostridium difficile from neonatal pigs with enteritis. MICs(50) for erythromycin, tilmicosin, and tylosin were relatively low (0.25-0.50 microg/mL), but MICs(90) (64 or > or =256 microg/mL) suggest in vivo resistance of a proportion of isolates. Susceptibility to tetracycline varied widely, with MIC(50) and MIC(90) of 8 and 32 microg/mL, respectively. The MICs(90) for tiamulin (8 microg/mL) and virginiamycin (16 microg/mL) suggest moderate susceptibility. Bacitracin and ceftiofur (MICs(90) > or =256 microg/mL) have little activity against C. difficile. Tiamulin and virginiamycin may decrease fecal shedding of C. difficile by sows, and erythromycin, tetracycline, and tylosin may be useful for treatment of infected piglets.

Frequency of binary toxin genes among Clostridium difficile strains that do not produce large clostridial toxins

Pathogenic strains of Clostridium difficile commonly produce two large clostridial toxins (LCTs), A and B, virulence factors responsible for C. difficile disease. Some strains have been reported to produce an additional toxin, a binary toxin designated CDT. Binary toxin has cytotoxic effects on cells in culture, but its role in human disease is not yet defined. In this study we examined the frequency of binary toxin genes (cdtB and cdtA) among C. difficile isolates that do not produce LCTs (A(-) B(-)) from a large United States-based collection organized by restriction endonuclease analysis (REA) typing. Of 58 strains tested, 9 (15.5%) were cdtB and cdtA positive, including 4 of 46 (8.7%) non-LCT-producing REA groups, with an estimated prevalence of at least 2% of all non-LCT-producing isolates within the collection. Five of the binary toxin-positive strains belonged to toxinotype XI, which does not produce LCTs but has minor parts of the LCT coding region or pathogenicity locus (PaLoc). We describe two new binary toxin-positive variants, one without any remnant of the LCT genes. This previously unknown variation was found in three isolates that were unrelated by REA typing. LCT-negative, binary toxin-positive strains were isolated from symptomatic and asymptomatic patients and from the hospital environment.

Clostridium difficile infection in patients with unexplained leukocytosis

PURPOSE

To determine whether unrecognized Clostridium difficile infection is responsible for a substantial proportion of cases of unexplained leukocytosis in a tertiary care hospital setting.

METHODS

We prospectively identified 60 patients who had unexplained leukocytosis (white blood cell count > or =15,000/mm3). Fecal specimens were tested for C. difficile toxin using an enzyme immunosorbent assay. We compared the clinical features of patients who had positive or negative assay results, as well as of 26 hospitalized control patients who did not have unexplained leukocytosis.

RESULTS

Thirty-five (58%) of the patients with unexplained leukocytosis had C. difficile toxin in at least one fecal specimen as compared with 3 (12%) of the controls (P <0.001). Symptoms of colitis were often mild or absent at the time the white blood cell count was first elevated or, if present, had not been recognized by the attending physicians. Leukocytosis resolved promptly in most patients who were treated with metronidazole. In the 25 patients (42%) who had a negative test for C. difficile toxin, leukocytosis also tended to resolve during empiric therapy with metronidazole; some of these patients may have had C. difficile infection.

CONCLUSION

The majority of patients in our hospital who had unexplained leukocytosis had C. difficile infection. Unexplained leukocytosis in hospitalized patients should prompt a search for symptoms and signs consistent with C. difficile infection and a study to detect C. difficile. Empiric therapy with metronidazole may be effective in the appropriate epidemiologic setting.

Prevalence of Clostridium spp. and Clostridium difficile in children with acute diarrhea in São Paulo city, Brazil

Species of Clostridium are widely distributed in the environment, inhabiting both human and animal gastrointestinal tracts. Clostridium difficile is an important pathogen associated with outbreaks of pseudomembranous colitis and other intestinal disorders, such as diarrhea. In this study, the prevalence of Clostridium spp. and C. difficile, from hospitalized children with acute diarrhea, was examined. These children were admitted to 3 different hospitals for over 12 months. Eighteen (20%) and 19 (21%) stool specimens from children with (90) and without (91) diarrhea respectively, were positive to clostridia. Only 10 C. difficile strains were detected in 5.5% of the stool samples of children with diarrhea. None healthy children (without diarrhea) harbored C. difficile. From these 10 C. difficile, 9 were considered as toxigenic and genotyped as tcdA+/tcdB+ or tcdA-/tcdB+, and 1 strain as nontoxigenic (tcdA-/tdcB-). They were detected by the citotoxicity on VERO cells and by the multiplex-polymerase chain reaction. Thirty clinical fecal extracts produced minor alterations on VERO cells. The presence of C. difficile as a probable agent of acute diarrhea is suggested in several countries, but in this study, the presence of these organisms was not significant. More studies will be necessary to evaluate the role of clostridia or C. difficile in diarrhoeal processes in children.

Rapid detection of Clostridium difficile in feces by real-time PCR

Clostridium difficile is the major causative agent of nosocomial antibiotic-associated diarrhea, colitis, and pseudomembranous colitis. The pathogenicity of C. difficile is closely related to the production of toxins A and B. Toxigenic C. difficile detection by a tissue culture cytotoxin assay is often considered the "gold standard." However, this assay is time consuming, as it implies an incubation period of at least 24 h. We have developed a rapid real-time fluorescence-based multiplex PCR assay targeting the C. difficile toxin genes tcdA and tcdB, with the Smart Cycler. Two molecular beacons bearing different fluorophores were used as internal probes specific for each amplicon type. The analytical sensitivity of the assay was around 10 genome copies for all nine C. difficile strains tested, representing the 6 most common toxinotypes. The specificity was demonstrated by the absence of amplification with DNA purified from bacterial species other than C. difficile (n = 14), including Clostridium sordellii for which the lethal toxin gene sequence is closely related to the toxin genes of C. difficile. Following a rapid (15 min) and simple fecal sample preparation protocol, both tcdA and tcdB were efficiently amplified from 28 of 29 cytotoxin-positive feces samples. There was no amplification observed with all 27 cytotoxin-negative feces samples tested. This is the first real-time PCR assay for the detection of C. difficile. It is rapid, sensitive, and specific and allows detection of C. difficile directly from feces samples.

[Antibiotic induced diarrhea and pseudomembranous colitis]

The spore-forming anaerobic bacterium Clostridium difficile has become a serious enteropathogen. Oral and parenteral administration of antibiotics can cause ecological disturbances in the normal intestinal microflora. Suppression of the normal microflora may lead to reduced colonization resistance with subsequent overgrowth by pre-existing, naturally resistant microorganisms, such as C. difficile. C. difficile infection shows a range of clinical presentations between an asymptomatic carrier state, light diarrhea without inflammatory changes, and pseudomembranous colitis. C. difficile infection is acquired by the fecal-oral or environmental-oral routes. From March 2000 through March 2001 we assessed 48 cases of nosocomial antibiotic-associated diarrhea (AAD). Of these, 21 were due to C. difficile (CDAD). Cephalosporin was the agent most commonly associated with CDAD. Avoidance of cephalosporins, strict use of "single shot" prophylaxis, isolation of infected, symptomatic patients in single-bed rooms, improved hygiene and complete room disinfection lead to a rapid decrease of CDAD. The etiology, prognosis and prophylaxis are discussed in this paper.