New multiplex PCR method for the detection of Clostridium difficile toxin A (tcdA) and toxin B (tcdB) and the binary toxin (cdtA/cdtB) genes applied to a Danish strain collection

Enteroaggregative Escherichia coli in Daycare-A 1-Year Dynamic Cohort Study

Enteroaggregative Escherichia coli (EAEC) has been associated with persistent diarrhea, reduced growth acceleration, and failure to thrive in children living in developing countries and with childhood diarrhea in general in industrialized countries. The clinical implications of an EAEC carrier-status in children in industrialized countries warrants clarification. To investigate the pathological significance of an EAEC carrier-state in the industrialized countries, we designed a 1-year dynamic cohort study and performed follow-up every second month, where the study participants submitted a stool sample and answered a questionnaire regarding gastrointestinal symptoms and exposures. Exposures included foreign travel, consumption of antibiotics, and contact with a diseased animal. In the capital area of Denmark, a total of 179 children aged 0–6 years were followed in a cohort study, in the period between 2009 and 2013. This is the first investigation of the incidence and pathological significance of EAEC in Danish children attending daycare facilities. Conventional microbiological detection of enteric pathogens was performed at Statens Serum Institute, Copenhagen, Denmark, and at Hvidovre Hospital, Copenhagen, Denmark. Parents completed questionnaires regarding gastrointestinal symptoms. The EAEC strains were further characterized by serotyping, phylogenetic analysis, and susceptibility testing. EAEC was detected in 25 (14%) of the children during the observational period of 1 year. One or more gastrointestinal symptoms were reported from 56% of the EAEC-positive children. Diarrhea was reported in six (24%) of the EAEC positive children, but no cases of weight loss, and general failure to thrive were observed. The EAEC strains detected comprised a large number of different serotypes, confirming the genetic heterogeneity of this pathotype. EAEC was highly prevalent (n = 25, 14%) in Danish children in daycare centers and was accompanied by gastrointestinal symptoms in 56% of the infected children. No serotype or phylogenetic group was specifically linked to children with disease.

Clostridium difficile ribotype 176 - A predictor for high mortality and risk of nosocomial spread?

PURPOSE

The objective of this survey was to determine the incidence of Clostridium difficile infections (CDI) at the Department of Infectious Diseases, Bulovka Hospital, and to evaluate clinical and epidemiological data on CDI patients together with a detailed molecular characterisation of C. difficile isolates. The patient outcomes were correlated to causative C. difficile PCR-ribotype.

METHODS

The twelve-month study (2013) comprised patients two years of age and older with CDI. CDI severity was estimated using ESCMID criteria and ATLAS scoring. C. difficile isolates were further characterized using ribotyping, Multiple-Locus Variable Tandem-Repeats analysis (MLVA) and investigation of antibiotic-resistance determinants (gyrA, gyrB, rpoB, ermB).

RESULTS

A total of 619 diarrhoeal stools were investigated. Seventy-two stool samples were GDH and toxin A/B positive, and 39 samples were GDH positive only and subsequently toxigenic C. difficile was cultured. In total, 111 C. difficile isolates were characterized, of which 64 (57.7%) belonged to PCR-ribotype 176. MLVA analysis of PCR-ribotype 176 isolates revealed 11 clonal complexes. Seventy-two isolates (64.9%) showed amino acid substitution Thr82Ile in the GyrA, and sixty-two isolates (55.9%) showed amino acid substitutions Arg505Lys together with His502Asn, or Asp492Glu together with Arg505Lys in the RpoB. Twelve isolates (10.8%) were ermB positive. Severe CDI according to the ESCMID criteria was recorded in forty-two patients (37.8%), and sixteen patients (14.4%) had ATLAS score ≥ 6. Twenty-nine patients (26.1%) had recurrent CDI and twenty-four patients (21.6%) died during the study period.

CONCLUSIONS

A higher rate of severe CDI, recurrences and mortality in association with PCR-ribotype 176 infections were observed. The high incidence of PCR-ribotype 176 in the study, and the presence of clonal relatedness between PCR-ribotype 176 isolates, indicate its higher capacity to spread in a hospital setting, which in turn highlights the need to implement strict epidemic measures when PCR-ribotype 176 occurs.

Molecular and epidemiologic study of Clostridium difficile reveals unusual heterogeneity in clinical strains circulating in different regions in Portugal

Clostridium difficile infection (CDI) represents a great healthcare burden in developed countries. The emergence of the epidemic PCR ribotype (RT) 027 and its acquired fluoroquinolones resistance have accentuated the need for an active surveillance of CDI. Here we report the first countrywide study of CDI in Portugal with the characterization of 498 C. difficile clinical isolates from 20 hospitals in four regions in Portugal regarding RT, virulence factors and antimicrobial susceptibility. We identified 96 RTs with marked variations between and within regions, as only six RTs appeared in all four regions. RT027 was the most frequent RT overall (18.5%) and among healthcare facility-associated isolates (19.6%), while RT014 was the most common among community-associated isolates (12%). The north showed a high RT diversity among isolates and a low moxifloxacin (MXF) resistance rate (11.9%), being the only region in which RT027 was not predominant. In contrast, the isolates from the centre presented the highest RT027 frequency, and 53.4% were resistant to MXF. Overall, MXF resistance (33.2%) was associated (p <0.001) with the presence of binary toxin genes and mutations in tcdC regardless of the RT. Both traits appeared in almost 30% of the strains. RT027 showed a reduced susceptibility to metronidazole (p <0.01), and RT126 had higher minimum inhibitory concentrations to vancomycin (p = 0.03) compared to other RTs. The present study highlights an unusual heterogeneity of RTs in Portugal, with a high frequency of hypervirulent RTs and the emergence of virulence factors in non-027 RTs, emphasizing the need for a surveillance system for CDI in Portugal.

A pilot study to assess bacterial and toxin reduction in patients with Clostridium difficile infection given fidaxomicin or vancomycin

BACKGROUND

To assess the effect of fidaxomicin and vancomycin on Clostridium difficile toxins and correlation with clinical and microbiologic outcomes.

METHODS

Hospitalized patients with C. difficile infection were randomly assigned a 10-day course of fidaxomicin or vancomycin. Stool samples collected at baseline (day 0), mid-therapy (days 3-5), end of therapy (days 10-13) and follow-up (days 19-38) were assessed for quantity of toxins A and B as well as spore and vegetative cells counts. Correlation of toxins concentrations with microbiologic and clinical findings were evaluated.

RESULTS

Among 34 patients 12 had detectable toxin concentrations at baseline seven were randomized to fidaxomicin and five to vancomycin. Overall both fidaxomicin and vancomycin resulted in drop of both toxins concentrations by midpoint of therapy. The drop in toxin A concentrations was maintained up to the follow-up period with fidaxomicin but not with vancomycin even in patients who developed recurrence. Patients who developed recurrence in the fidaxomicin group had lower concentrations of toxin B versus the recurrence patient of vancomycin group. Presence of vegetative cells and spores was significantly linked with high toxin A (P = 0.003 and <0.001 respectively) and toxin B (P = 0.007 and <0.001 respectively) concentrations across time points. Toxin B concentrations but not A significantly correlated with stool consistency (P < 0.001) and frequency (P = 0.05).

CONCLUSIONS

Fidaxomicin was associated with sustained reduction of both toxins up to 30 days post therapy versus vancomycin. Multiple clinical or microbiologic observations were correlated with toxin A or B concentrations.

Complete genome sequence of Peptoclostridium difficile strain Z31

BACKGROUND

Peptoclostridium (Clostridium) difficile is a spore-forming bacterium responsible for nosocomial infections in humans. It is recognized as an important agent of diarrhea and colitis in several animal species and a possible zoonotic agent. Despite the known importance of P. difficile infection in humans and animals, no vaccine or other effective measure to control the disease is commercially available. A possible alternative treatment for P. difficile infection is the use of a nontoxigenic strain of P. difficile as a competitive exclusion agent. However, a thorough knowledge of this strain is necessary for this purpose. We selected P. difficile Z31, a nontoxigenic strain (PCR ribotype 009), for investigation because it prevents P. difficile infection in a hamster model.

RESULTS

The genome sequence of P. difficile Z31 is a circular chromosome of 4298,263 bp, with a 29.21 % GC content, encoding 4128 proteins, and containing 78 pseudogenes. This strain belongs to ST 3, clade 1, and has five phage regions in its genome. Genes responsible for resistance to tetracycline and erythromycin were detected and more importantly, Z31 also contains genes that promote spore production and stability, cell attachment, intestinal adherence, and biofilm formation.

CONCLUSION

In this study, we present the first complete genome sequence of nontoxigenic P. difficile strain Z31. When the Z31 genome was compared with those of other isolates available in GenBank, including a draft genome of a nontoxigenic strain, several unique regions were evident. Z31 contains no toxin genes, but encodes several non-toxin virulence factors, which may favor host colonization.

Molecular Characterization of Clostridium difficile Isolates from Human Subjects and the Environment

Clostridium difficile is a spore-forming, gram-positive, anaerobic bacillus that can cause C. difficile infection (CDI). However, only a few studies on the prevalence and antibiotic resistance of C. difficile in healthy individuals in China have been reported. We employed a spore enrichment culture to screen for C. difficile in the stool samples of 3699 healthy Chinese individuals who were divided into 4 groups: infants younger than 2 years of age and living at home with their parents; children aged 1 to 8 years of age and attending three different kindergarten schools; community-dwelling healthy adult aged 23-60 years old; and healthcare workers aged 28-80 years old. The C. difficile isolates were analyzed for the presence of toxin genes and typed by PCR ribotyping and multilocus sequence typing (MLST). The minimum inhibitory concentration of 8 antimicrobial agents was determined for all of the isolates using the agar dilution method. The intestinal carriage rate in the healthy children was 13.6% and ranged from 0% to 21% depending on age. The carriage rates in the 1654 community-dwelling healthy adults and 348 healthcare workers were 5.5% and 6.3%, respectively. Among the isolates, 226 were toxigenic (225 tcdA+/tcdB+ and 1 tcdA+/tcdB+ ctdA+/ctdB+). Twenty-four ribotypes were found, with the dominant type accounting for 29.7% of the isolates. The toxigenic isolates were typed into 27 MLST genotypes. All of the strains were susceptible to vancomycin, metronidazole, fidaxomicin, and rifaximin. High resistance to levofloxacin and ciprofloxacin at rates of 39.8% and 98.3%, respectively, were observed. ST37 isolates were more resistant to levofloxacin than the other STs. The PCR ribotypes and sequence types from the healthy populations were similar to those from the adult patients.

The First Two Clostridium difficile Ribotype 027/ST1 Isolates Identified in Beijing, China-an Emerging Problem or a Neglected Threat?

Clostridium difficile hyper-virulent ribotype 027 strain has become a significant concern globally, but has rarely been reported in Asian countries including China. Recently, a retrospective single-center study in Beijing, China, detected two ribotype 027 C. difficile isolates from two patients coming for outpatient visits in 2012 and 2013. We performed a systematic investigation of the two isolates (and patients). Both C. difficile isolates had the typical PCR ribotype 027 profile; were positive for tcdA, tcdB and binary toxin genes; belonged to multilocus sequence type 1 (ST1); had typical ribotype 027 deletions in the tcdC gene; and were highly-resistant to fluoroquinolones; but had a different MLVA profile and were not genetically related to any previously reported international ribotype 027 clones. A review of the patients' medical records showed that neither received appropriate antimicrobial treatment and were lost to follow-up after outpatient visits. We propose that C. difficile infections caused by ribotype 027 are probably a neglected problem in China, and the subsequent impact of unawareness of this problem is worrying. Appropriate testing assays and multi-center or national level surveillance for C. difficile infections and specifically for ribotype 027 should be introduced to provide essential data and guide future clinical practice.

Clinical features and characteristics of Clostridium difficile PCR-ribotype 176 infection: results from a 1-year university hospital internal ward study

Background

Clostridium difficile infection (CDI) is a major cause of antibiotic-associated diarrhoea. Given an increasing CDI incidence and global spread of epidemic ribotypes, a 1-year study was performed to analyse the molecular characteristics of C. difficile isolates and associated clinical outcomes from patients diagnosed with CDI in the Internal Medicine department at University Hospital Motol, Prague from February 2013 to February 2014.

Results

A total of 85 unformed stool samples were analysed and CDI was laboratory confirmed in 30 patients (6.8 CDI cases per 10,000 patient bed days and 50.6 CDI cases per 10,000 admissions). The CDI recurrence rate within 3 months of treatment discontinuation was 13.3% (4/30). Mortality within 3 months after first CDI episode was 26.7% (8/30), with CDI the cause of death in two cases. 51.9% of C. difficile isolates belonged to PCR-ribotype 176. MLVA of ribotype 176 isolates revealed two clonal complexes formed by 10/14 isolates. ATLAS scores and Horn’s index were higher in patients with ribotype 176 infections than with non-ribotype 176 infections.

Conclusion

This study highlights the clinical relevance of C. difficile PCR-ribotype 176 and its capacity to spread within a healthcare facility.

The Role of Glutamate Dehydrogenase (GDH) Testing Assay in the Diagnosis of Clostridium difficile Infections: A High Sensitive Screening Test and an Essential Step in the Proposed Laboratory Diagnosis Workflow for Developing Countries like China

The incidence and severity of Clostridium difficile infection (CDI) in North America and Europe has increased significantly since the 2000s. However, CDI is not widely recognized in China and other developing countries due to limited laboratory diagnostic capacity and low awareness. Most published studies on laboratory workflows for CDI diagnosis are from developed countries, and thus may not be suitable for most developing countries. Therefore, an alternative strategy for developing countries is needed. In this study, we evaluated the performance of the Glutamate Dehydrogenase (GDH) test and its associated workflow on 416 fecal specimens from suspected CDI cases. The assay exhibited excellent sensitivity (100.0%) and specificity (92.8%), compared to culture based method, and thus could be a good screening marker for C. difficile but not for indication of toxin production. The VIDAS CDAB assay, which can detect toxin A/B directly from fecal specimens, showed good specificity (99.7%) and positive predictive value (97.2%), but low sensitivity (45.0%) and negative predictive value (88.3%), compared with PCR-based toxin gene detection. Therefore, we propose a practical and efficient GDH test based workflow strategy for the laboratory diagnosis of CDI in developing countries like China. By applying this new workflow, the CDI laboratory diagnosis rate was notably improved in our center, yet the increasing cost was kept at a minimum level. Furthermore, to gain some insights into the genetic population structure of C. difficile isolates from our hospital, we performed MLST and PCR toxin gene typing.

Longitudinal study of Clostridium difficile shedding in raccoons on swine farms and conservation areas in Ontario, Canada

Background

Clostridium difficile is an important enteropathogen affecting humans, domestic animals, and wildlife. The objectives of this study were to 1) compare the prevalence and characteristics of C. difficile isolated from the feces of raccoons trapped on swine farms and conservation sites, and 2) investigate the role of raccoons as potential reservoirs for host-adapted strains of C. difficile using a longitudinal study. Fecal swabs were collected from raccoons at 5 conservation sites and 5 swine farms, once every five weeks, from May to November, 2012.

Results

Clostridium difficile was isolated from 9 % (38/444) of samples, from 12 % (37/302) of raccoons, from all 10 sites. A total of 19 different ribotypes were identified, including 5 ribotypes that matched recognized international designations and which are also found in humans (001, 014, 056, 078, and 103). Location type (farm or conservation area) was not associated with C. difficile status (P = 0.448) but only 3 ribotypes (014, 056, and 078) were found in both location types. The prevalence of ribotype 078 was significantly higher on farms (4 %; 9/220) compared to conservation sites (1 %; 2/225) (P = 0.034). Only one of 108 raccoons caught in multiple sessions was positive on more than one occasion.

Conclusions

We found no evidence to support the hypothesis that raccoons harbour host-adapted strains of C. difficile; rather, it appears that raccoons transiently acquire C. difficile from the environment. Raccoons are unlikely to be maintaining C. difficile, but because we detected C. difficile strains that have the potential to cause illness in humans and livestock, and because raccoons can move relatively large distances, they may play a role in the dissemination of pathogenic ribotypes of C. difficile throughout the environment.

Association of Clostridium difficile ribotype 078 with detectable toxin in human stool specimens

Using a Clostridium difficile glutamate dehydrogenase (GDH) immunoassay and a sensitive C. difficile toxin A/B immunoassay, human stool specimens from patients with diarrhoea (n = 1085) were classified as either GDH positive/toxin negative, or GDH positive/toxin positive. Overall, 528/725 (73%) of the GDH-positive/toxin-negative specimens contained viable C. difficile, and 433/528 (82%) of these C. difficile isolates were PCR positive for the toxin gene pathogenicity locus. Overall, 867/1078 (80%) of the GDH-positive specimens contained viable C. difficile, and 433/725 (60%) of the GDH-positive/toxin-negative specimens contained a toxigenic C. difficile strain. The diversity of toxigenic C. difficile ribotypes isolated from toxin-negative specimens (n = 433) and toxin-positive specimens (n = 339) was significantly different (P < 0.0001). Specifically, the presence of ribotype 078 strains was very strongly associated (P < 0.0001) with detection of toxin in clinical specimens using a sensitive toxin immunoassay. Specimens positive for ribotype 078 were almost twice as likely to be toxin positive as opposed to toxin negative (risk ratio = 1.90, 95% confidence interval 1.64-2.19). In contrast, other circulating ribotypes were seen with similar frequency in specimens with and without detectable toxin. This supports the view that ribotype 078 strains may be more virulent than other common ribotypes in terms of toxin production.

U.S.-Based National Sentinel Surveillance Study for the Epidemiology of Clostridium difficile-Associated Diarrheal Isolates and Their Susceptibility to Fidaxomicin

In 2011 a surveillance study for the susceptibility to fidaxomicin and epidemiology of Clostridium difficile isolates in the United States was undertaken in seven geographically dispersed medical centers. This report encompasses baseline surveillance in 2011 and 2012 on 925 isolates. A convenience sample of C. difficile isolates or toxin positive stools from patients were referred to a central laboratory. Antimicrobial susceptibility was determined by agar dilution (CLSI M11-A8). Clinical and Laboratory Standards Institute (CLSI), Food and Drug Administration, or European Union of Clinical Antimicrobial Susceptibility Testing (EUCAST) breakpoints were applied where applicable. Toxin gene profiles were characterized by multiplex PCR on each isolate. A random sample of 322 strains, stratified by institution, underwent restriction endonuclease analysis (REA). The fidaxomicin MIC90 was 0.5 μg/ml for all isolates regardless of REA type or toxin gene profile, and all isolates were inhibited at ≤1.0 μg/ml. By REA typing, BI strains represented 25.5% of the isolates. The toxin gene profile of tcdA, tcdB, and cdtA/B positive with a tcdC 18-bp deletion correlated with BI REA group. Moxifloxacin and clindamycin resistance was increased among either BI or binary toxin-positive isolates. Metronidazole and vancomycin showed reduced susceptibility (EUCAST criteria) in these isolates. Geographic variations in susceptibility, REA group and binary toxin gene presence were observed. Fidaxomicin activity against C. difficile isolated in a national surveillance study did not change more than 1 year after licensure. This analysis provides baseline results for future comparisons.

Accurate detection of binary toxin producer from Clostridium difficile by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Thirsty-six binary toxin producers were detected with 2 genotypes (cdtA(+) and cdtB(+)) among 265 Clostridium difficile isolates by multiplex PCR. The rate of accurate differentiation between these 2 genotypes was 100% by 6-peak cluster analysis of spectra generated by Bruker Biotyper matrix-assisted laser desorption ionization/time-of-flight mass spectrometry.

Role of binary toxin in the outcome of Clostridium difficile infection in a non-027 ribotype setting

Binary toxin (BT) has been associated with strains causing more severe Clostridium difficile infection (CDI), such as ribotype 027. Data on the outcome of patients having BT present in ribotypes other than 027 are scarce. Our objective was to investigate the association between BT isolates and outcome of CDI in a non-027 ribotype setting. We prospectively included CDI episodes (January-June 2013 and March-June 2014) from symptomatic patients aged >2 years. Epidemiological and clinical data were recorded. BT genes were detected using multiplex PCR. During the study period, we identified 326 episodes of CDI, of which 319 were available for molecular analysis. Of these, 54 (16·9%) were caused by C. difficile strains with BT. Most (90·7%) isolates with BT were ribotype 078/126. CDI patients with BT-positive strains did not differ from those with BT-negative strains in terms of recurrence (13·0% vs. 15·5%, P = 0·835), treatment failure (0·0% vs. 2·3%, P = 0·594), overall mortality (11·1% vs. 9·1%, P = 0·612), or CDI-related mortality (0·0% vs. 1·9%, P = 0·612). Multivariate regression revealed no association between BT and poor outcome. In conclusion, in a non-027 setting, we found that most BT isolates were 078/126 and were not associated with poor outcome.

A national survey of the molecular epidemiology of Clostridium difficile in Israel: the dissemination of the ribotype 027 strain with reduced susceptibility to vancomycin and metronidazole

Our goals were to study the molecular epidemiology and antimicrobial susceptibilities of C. difficile strains in Israel. Microbiology laboratories serving 6 general hospitals (GH) and 10 long-term care facilities (LTCF) were asked to submit all stool samples in January-February 2014 that tested positive for C. difficile. Toxigenic C. difficile isolates were recovered in 208 out of 217 samples (95.8%), of which 50 (23.6%) were from LTCFs. Ribotype 027 was the most common type overall, identified in 65 samples (31.8%), and was the predominant strain in the 3 GHs with the highest incidence of C. difficile infections. Other common strains were slpA types cr-02 (n = 45) and hr-02 (n = 18). The proportions of vancomycin and metronidazole MIC values >2mg/L were high in ribotype 027 (87.7% and 44.6%, respectively) and slpA-cr-02 strains (88.8% and 17.8%, respectively). This study demonstrates that the ribotype 027 strain has disseminated across Israel and is now the most common strain.

Clostridium difficile PCR Ribotype 018, a Successful Epidemic Genotype

Clostridium difficile infection (CDI) became a public health problem for the global spreading of the so-called hypervirulent PCR ribotypes (RTs) 027 and 078, associated with increases in the transmission and severity of the disease. However, especially in Europe, several RTs are prevalent, and the concept of hypervirulence is currently debated. We investigated the toxin and resistance profiles and the genetic relatedness of 312 C. difficile strains isolated in a large Italian teaching hospital during a 5-year period. We evaluated the role of CDI-related antibiotic consumption and infection control practices on the RT predominance in association with their molecular features and transmission capacity. Excluding secondary cases due to nosocomial transmission, RT018 was the predominant genotype (42.4%) followed by RT078 (13.6%), while RT027 accounted for 0.8% of the strains. RT078 was most frequently isolated from patients in intensive care units. Its prevalence significantly increased over time, but its transmission capacity was very low. In contrast, RT018 was highly transmissible and accounted for 95.7% of the secondary cases. Patients with the RT018 genotype were significantly older than those with RT078 and other RTs, indicating an association between epidemic RT and age. We provide here the first epidemiological evidence to consider RT018 as a successful epidemic genotype that deserves more attention in clinical practice.

Molecular Epidemiology of Clostridium difficile Infection in a Large Teaching Hospital in Thailand

Clostridium difficile infection (CDI) is a leading cause of healthcare-associated morbidity and mortality worldwide. In Thailand, CDI exhibits low recurrence and mortality and its molecular epidemiology is unknown. CDI surveillance was conducted in a tertiary facility (Siriraj Hospital, Bangkok). A total of 53 toxigenic C. difficile strains from Thai patients were analyzed by multi-locus sequence typing (MLST), PCR ribotyping, and pulse-field gel electrophoresis (PFGE). The mean age of the cohort was 64 years and 62.3% were female; 37.7% of patients were exposed to > two antibiotics prior to a diagnosis of CDI, with beta-lactams the most commonly used drug (56.3%). Metronidazole was used most commonly (77.5%; success rate 83.9%), and non-responders were treated with vancomycin (success rate 100%). None of the isolates carried binary toxin genes. Most isolates (98.2–100%) were susceptible to metronidazole, vancomycin, tigecycline and daptomycin. There were 11 sequence types (STs), 13 ribotypes (RTs) and four PFGE types. Six previously identified STs (ST12, ST13, ST14, ST33, ST41 and ST45) and five novel STs unique to Thailand (ST66, ST67, ST68, ST69 and ST70) were identified. PCR RTs UK 017 (ST45) (45.3%) and UK 014/020 (ST33) (24.5%) were the most common. High concordance was observed between the MLST and ribotyping results (p<0.001). C. difficile isolates from Thai patients were highly susceptible to standard antimicrobial agents. In conclusion, the five STs indicate the high genetic diversity and unique polymorphisms in Thailand. Moreover, the emergence of antimicrobial resistance to vancomycin warranted continuous surveillance to prevent further spread of the toxigenic C. difficile isolates.

Toxigenic Clostridium difficile PCR ribotypes in edible marine bivalve molluscs in Italy

Even though food of animal sources and different foodstuffs are well known to be potentially carrier of Clostridium difficile, few data are available on the occurrence of C. difficile in seafood. This work investigated the occurrence of C. difficile in edible bivalve molluscs in southern Italy. Out of the 925 investigated samples, 3.9% contained C. difficile. Eighteen strains harboured both genes for toxins A and B whereas 1 only had toxin B gene. Binary toxin genes were found in 22.2% of the isolates. The most frequently ribotypes found were 078/126 (22.2%), 010 (19.4%), and 001 (8.3%). All isolates were susceptible to metronidazole, vancomycin, fidaxomicin, and to the new semisynthetic thiopeptide antibiotic LFF571, whereas 19.4% of them were resistant to moxifloxacin, 30.5% to clindamycin, 38.8% to erythromycin, and 100% to ciprofloxacin. This study points out that edible molluscs could be a potential source of toxigenic C. difficile ribotypes and a potential risk for human health.

Clostridium difficile ribotype 078 cultured from post-surgical non-healing wound in a patient carrying ribotype 014 in the intestinal tract

Extra-intestinal infections caused by Clostridium difficile are rare. The risk of extra-intestinal infections associated with C. difficile may be particularly relevant in environments contaminated with C. difficile spores. This paper describes the case of a non-diarrheic patient colonized with C. difficile ribotype 014 in the intestinal tract who developed a post-surgical wound infection by C. difficile ribotype 078. The infection responded to metronidazole administered first intravenously and then orally. This case indicates that C. difficile may not only be related to diarrheic diseases, but also to infections of non-healing wounds, especially in situations when C. difficile is the only isolated pathogen.

Report of an outbreak of Clostridium difficile infection caused by ribotype 053 in a neurosurgery unit

BACKGROUND

We describe an outbreak of Clostridium difficile infection (CDI) with ribotype 053, a possible hypervirulent strain that causes outbreaks, in a neurosurgical unit.

OUTBREAK INVESTIGATION

The outbreak was investigated by creating a timeline of all toxin positive patients with root cause analysis, supplemented with ribotyping results, hand hygiene and environmental audits. There were five cases of CDI, three caused by ribotype 053 indicating transmission.

INFECTION PREVENTION MEASURES

These included a short period of ward closure to allow enhanced cleaning, including use of vaporised hydrogen peroxide, isolation of infected patients, reinforcement of hand hygiene, education of all staff on C. difficile, reduction of shared bay occupancy from six to four, and addressing staffing levels.

DISCUSSION

The patients with ribotype 053 all had long inpatient stays and had required several courses of broad-spectrum antibiotics for aspiration pneumonia. They also required enteral feeding, which can cause diarrhoea, and during long inpatient stays they had multiple toxin negative faecal samples making clinical diagnosis of CDI difficult. Hence they were not isolated promptly, leading to transmission. This is the first reported outbreak of C. difficile ribotype 053 in the UK and highlights the unique aspects of an outbreak in neurosurgical patients.

Impact of clinical awareness and diagnostic tests on the underdiagnosis of Clostridium difficile infection

A multicenter study of Clostridium difficile infection (CDI) performed during 2008 in Spain revealed that two of every three episodes went undiagnosed or were misdiagnosed owing to nonsensitive diagnostic tests or lack of clinical suspicion and request. Since then, efforts have been made to improve the diagnostic tests used by laboratories and to increase the awareness of this disease among both clinicians and microbiologists. Our objective was to evaluate the impact of these efforts by assessing the current magnitude of underdiagnosis of CDI in Spain using two point-prevalence studies performed on one day each in January and July of 2013. A total of 111 Spanish laboratories selected all unformed stool specimens received for microbiological diagnosis on these days, and toxigenic culture was performed at a central reference laboratory. Toxigenic isolates were characterized both pheno- and genotypically. The reference laboratory detected 103 episodes of CDI in patients aged 2 years or more. Half (50.5 %) of the episodes were not diagnosed in the participating laboratories, owing to insensitive diagnostic tests (15.5 %) or the lack of clinical suspicion and request (35.0 %). The main ribotypes were 014, 078/126, 001/072, and 106. Ribotype 027 caused 2.9 % of all cases. Despite all the interventions undertaken, CDI remains a highly neglected disease because of the lack of sensitive diagnostic tests in some institutions and, especially, the absence of clinical suspicion, mainly in patients with community-associated CDI. Toxigenic C. difficile should be routinely sought in unformed stools sent for microbiological diagnosis, regardless of their origin.

Multiplex Real-Time PCR Method for Simultaneous Identification and Toxigenic Type Characterization of Clostridium difficile From Stool Samples

Background

The aim of this study was to develop and validate a multiplex real-time PCR assay for simultaneous identification and toxigenic type characterization of Clostridium difficile.

Methods

The multiplex real-time PCR assay targeted and simultaneously detected triose phosphate isomerase (tpi) and binary toxin (cdtA) genes, and toxin A (tcdA) and B (tcdB) genes in the first and sec tubes, respectively. The results of multiplex real-time PCR were compared to those of the BD GeneOhm Cdiff assay, targeting the tcdB gene alone. The toxigenic culture was used as the reference, where toxin genes were detected by multiplex real-time PCR.

Results

A total of 351 stool samples from consecutive patients were included in the study. Fifty-five stool samples (15.6%) were determined to be positive for the presence of C. difficile by using multiplex real-time PCR. Of these, 48 (87.2%) were toxigenic (46 tcdA and tcdB-positive, two positive for only tcdB) and 11 (22.9%) were cdtA-positive. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of the multiplex real-time PCR compared with the toxigenic culture were 95.6%, 98.6%, 91.6%, and 99.3%, respectively. The analytical sensitivity of the multiplex real-time PCR assay was determined to be 103colonyforming unit (CFU)/g spiked stool sample and 0.0625 pg genomic DNA from culture. Analytical specificity determined by using 15 enteric and non-clostridial reference strains was 100%.

Conclusions

The multiplex real-time PCR assay accurately detected C. difficile isolates from diarrheal stool samples and characterized its toxin genes in a single PCR run.

Comparison of Clostridium difficile isolates from individuals with recurrent and single episode of infection

PURPOSE

Recurrent Clostridium difficile infection (CDI) is an increasing problem, yet reasons for this are poorly understood. Attention has been paid to the role of strain, with conflicting association of ribotype 027 and recurrences.

METHODS

Stool samples and medical records data were collected from 60 patients: 27 with recurrent CDI and 33 with single episode CDI. C. difficile was isolated and ribotyped, and minimum inhibitory concentrations of metronidazole and vancomycin were determined by Etest.

RESULTS

Twenty-seven ribotypes were identified, but only four (027, 014 and two internally designated strains) were found in more than one patient. Ribotype 027 predominated and was significantly over-represented in the recurrent CDI group (70%) versus the single episode CDI group (30%) (P = 0.004). Female gender and the presence of ribotype 027 were significantly associated with recurrent CDI in the multivariable model. Metronidazole MICs for recurrent isolates were significantly higher compared to single episode isolates (P ≤ 0.024). A general linear model indicated that the difference in MIC was associated with ribotype 027 (P = 0.0023), not whether the isolate was from recurrent or single episode disease (P = 0.25).

CONCLUSIONS

Ribotype 027 was associated with recurrent disease. While there was no difference in the prevalence of metronidazole resistance, isolates from recurrent CDI patients had significantly higher metronidazole MICs, because of higher MICs in ribotype 027. This study provides further support to the clinical importance of ribotype 027 and raises questions about the potential impact of decreased metronidazole susceptibility on the pathophysiology of recurrent CDI.

Burden of Clostridium difficile infection in the United States

BACKGROUND

The magnitude and scope of Clostridium difficile infection in the United States continue to evolve.

METHODS

In 2011, we performed active population- and laboratory-based surveillance across 10 geographic areas in the United States to identify cases of C. difficile infection (stool specimens positive for C. difficile on either toxin or molecular assay in residents ≥ 1 year of age). Cases were classified as community-associated or health care-associated. In a sample of cases of C. difficile infection, specimens were cultured and isolates underwent molecular typing. We used regression models to calculate estimates of national incidence and total number of infections, first recurrences, and deaths within 30 days after the diagnosis of C. difficile infection.

RESULTS

A total of 15,461 cases of C. difficile infection were identified in the 10 geographic areas; 65.8% were health care-associated, but only 24.2% had onset during hospitalization. After adjustment for predictors of disease incidence, the estimated number of incident C. difficile infections in the United States was 453,000 (95% confidence interval [CI], 397,100 to 508,500). The incidence was estimated to be higher among females (rate ratio, 1.26; 95% CI, 1.25 to 1.27), whites (rate ratio, 1.72; 95% CI, 1.56 to 2.0), and persons 65 years of age or older (rate ratio, 8.65; 95% CI, 8.16 to 9.31). The estimated number of first recurrences of C. difficile infection was 83,000 (95% CI, 57,000 to 108,900), and the estimated number of deaths was 29,300 (95% CI, 16,500 to 42,100). The North American pulsed-field gel electrophoresis type 1 (NAP1) strain was more prevalent among health care-associated infections than among community-associated infections (30.7% vs. 18.8%, P<0.001).

CONCLUSIONS

C. difficile was responsible for almost half a million infections and was associated with approximately 29,000 deaths in 2011. (Funded by the Centers for Disease Control and Prevention.).

Clostridium difficile PCR Ribotype 027 Emerges in Taiwan

Clostridium difficile PCR ribotype 027 is a hypervirulent strain that has caused significant nosocomial diarrhea in many countries but has not yet been reported or isolated in Taiwan previously. Here, we present the characteristics of a case of C. difficile PCR ribotype 027 identified in Taiwan. Taiwan is located in a key transportation center of Asia. This report is important for alerting hospitals and public health departments in Asia about the emergence of this hypervirulent strain so that close monitoring may be enacted to prevent potential outbreaks.

Clostridium difficile with Moxifloxacin/Clindamycin Resistance in Vegetables in Ohio, USA, and Prevalence Meta-Analysis

We (i) determined the prevalence of Clostridium difficile and their antimicrobial resistance to six antimicrobial classes, in a variety of fresh vegetables sold in retail in Ohio, USA, and (ii) conducted cumulative meta-analysis of reported prevalence in vegetables since the 1990s. Six antimicrobial classes were tested for their relevance as risk factors for C. difficile infections (CDIs) (clindamycin, moxifloxacin) or their clinical priority as exhaustive therapeutic options (metronidazole, vancomycin, linezolid, and tigecycline). By using an enrichment protocol we isolated C. difficile from three of 125 vegetable products (2.4%). All isolates were toxigenic, and originated from 4.6% of 65 vegetables cultivated above the ground (n = 3; outer leaves of iceberg lettuce, green pepper, and eggplant). Root vegetables yielded no C. difficile. The C. difficile isolates belonged to two PCR ribotypes, one with an unusual antimicrobial resistance for moxifloxacin and clindamycin (lettuce and pepper; 027-like, A⁺B⁺CDT⁺; tcdC 18 bp deletion); the other PCR ribotype (eggplant, A⁺B⁺ CDT⁻; classic tcdC) was susceptible to all antimicrobials. Results of the cumulative weighted meta-analysis (6 studies) indicate that the prevalence of C. difficile in vegetables is 2.1% and homogeneous (P < 0.001) since the first report in 1996 (2.4%). The present study is the first report of the isolation of C. difficile from retail vegetables in the USA. Of public health relevance, antimicrobial resistance to moxifloxacin/clindamycin (a bacterial-associated risk factor for severe CDIs) was identified on the surface of vegetables that are consumed raw.

Molecular epidemiology and antimicrobial susceptibility of Clostridium difficile isolated from a university teaching hospital in Japan

Clostridium difficile infection control strategies require an understanding of its epidemiology. In this study, we analysed the toxin genotypes of 130 non-duplicate clinical isolates of C. difficile from a university hospital in Tokyo, Japan. Multilocus sequence typing (MLST) and eBURST analysis were performed for these isolates and nine strains previously analysed by polymerase chain reaction (PCR) ribotyping. Minimum inhibitory concentrations (MICs) were determined for six antibiotics, and the bacterial resistance mechanisms were investigated. Ninety-five toxigenic strains (73%), including seven tcdA-negative, tcdB-positive and cdtA/cdtB-negative strains (A(-)B(+)CDT(-)) and three A(+)B(+)CDT(+) strains, and 35 (27%) non-toxigenic strains, were classified into 23 and 12 sequence types, respectively. Of these, sequence type (ST)17 (21.8%) was the most predominant. MLST and eBURST analysis showed that 139 strains belonged to seven groups and singletons, and most A(+)B(+)CDT(-) strains (98%, 89/91) were classified into group 1. All isolates were susceptible to metronidazole, vancomycin and meropenem; the ceftriaxone, clindamycin and ciprofloxacin resistance rates were 49, 59 and 99%, respectively. Resistance rates to ceftriaxone and clindamycin were higher in toxigenic strains than in non-toxigenic strains (P < 0.001). All ST17 and ST81 strains were resistant to these antibiotics. The clindamycin- and fluoroquinolone-resistant strains carried erm(B) and mutations in GyrA and/or GyrB, respectively. To our knowledge, this is the first MLST-based study of the molecular epidemiology of toxigenic and non-toxigenic strains in Japan, providing evidence that non-toxigenic and toxigenic strains exhibit high genetic diversity and that toxigenic strains are more likely than non-toxigenic strains to exhibit multidrug resistance.

A new type of toxin A-negative, toxin B-positive Clostridium difficile strain lacking a complete tcdA gene

Toxins A and B are the main virulence factors of Clostridium difficile and are the targets for molecular diagnostic tests. Here, we describe a new toxin A-negative, toxin B-positive, binary toxin CDT (Clostridium difficile transferase)-negative (A(-) B(+) CDT(-)) toxinotype (XXXII) characterized by a variant type of pathogenicity locus (PaLoc) without tcdA and with atypical organization of the PaLoc integration site.

Clostridium difficile isolates with high linezolid MICs harbor the multiresistance gene cfr

We studied the molecular mechanisms of linezolid resistance in 9 isolates of toxigenic Clostridium difficile with high linezolid MICs. The activity of linezolid was determined against 891 clinical isolates of toxigenic C. difficile. The MIC50 and MIC90 of linezolid were 0.75 μg/ml and 1.5 μg/ml, respectively. Nine strains (1%) showed high linezolid MICs (6 μg/ml to 16 μg/ml) and also were resistant to clindamycin, erythromycin, and chloramphenicol. These strains were selected for molecular studies: sequencing of domain V of the 23 rRNA gene, detection of the cfr methyltransferase gene, and sequencing of the ribosomal protein genes rplC and rplD. Molecular relatedness between strains was assessed using PCR ribotyping and MLVA (multilocus variable-number tandem-repeat analysis) typing. The strains belonged to ribotypes 001 (2/9), 017 (6/9), and 078 (1/9). MLVA showed that strains of ribotype 001 and 017 belonged to the same clonal complex in each ribotype. We did not detect mutations in the 23S rRNA gene. The cfr gene was detected in 7 of 9 strains. Sequencing of cfr amplicons revealed a similarity of 100% to a fragment of transposon Tn6218 of C. difficile, which was annotated as a putative chloramphenicol/florfenicol resistance protein. We were unable to detect mechanisms of resistance to linezolid in the 2 strains belonging to ribotype 001. While the relevance of our results lies in the detection of the cfr gene as a possible mechanism of resistance to linezolid in C. difficile, our findings should be assessed by further investigations to characterize these possible cfr genes and their contribution to linezolid resistance.

ICU-Onset Clostridium difficile infection in a university hospital in China: a prospective cohort study

A prospective study was conducted to investigate the incidence, clinical profiles and outcome of ICU-onset CDI in a 50-bed medical ICU at a university hospital in China. Stools were collected from patients who developed ICU-onset diarrhea and was screened for tcdA (toxin A gene) and tcdB (toxin B gene) by PCR. CDI cases were compared with the ICU-onset non-CDI diarrhea cases for demographics, comorbidities, potential risk factors, major laboratory findings and outcomes. Stool samples from CDI cases were subjected to C. difficile culture and C. difficile isolates were screened for tcdA, tcdB and the binary toxin genes (cdtA and cdtB) using multiplex PCR. Strain typing of toxigenic C. difficile isolates was performed using multilocus sequence typing. There were 1,277 patients in the ICU during the study period and 124 (9.7%) developed ICU-onset diarrhea, of which 31 patients had CDI. The incidence of ICU-onset CDI was 25.2 cases per 10,000 ICU days. ICU-onset CDI cases had similar features with ICU-onset non-CDI diarrhea cases including the use of proton pump inhibitors and antibacterial agents. The crude mortality rate of ICU-onset CDI was 22.6%, but the attributable mortality rate of ICU-onset CDI was only 3.2% here. Toxigenic C. difficile isolates were recovered from 28 out of the 31 patients with CDI. cdtA and cdtB were found in two strains. Seventeen STs including 11 new STs were identified. All of the 11 new STs were single-locus variants of known STs and the 17 STs identified here could be clustered into 3 clades. The incidence of ICU-onset CDI here is similar to those in Europe and North America, suggesting that CDI is likely to be a common problem in China. Toxigenic C. difficile here belonged to a variety of STs, which may represent a significant clonal expansion rather than the true clonal diversity.

A search for Clostridium difficile ribotypes 027 and 078 in Brazil

Toxigenic strains of Clostridium difficile may be disseminating. Here we prospectively screened patients with nosocomial diarrhoea in two hospitals in Brazil. To identify C. difficile polymerase chain reaction ribotypes 027/078 strains, we used high resolution melting and multiplex polymerase chain reaction. Among 116 screened patients, 11 were positive for C. difficile. The polymerase chain reaction ribotypes 027/078 strains were not identified in this study.

Clostridium difficile infection: a review of the literature

Clostridium difficile is a Gram-positive, strictly anaerobic, spore-forming bacterium. It is the most common cause of antibiotic-associated diarrhea in hospitals and other healthcare facilities and is of significant concern because of the increasing morbidity and mortality rates as well as increased health care costs. Spectrum of presentation of Clostridium difficile infection ranges from mild, self-limiting diarrhea, to serious diarrhea, pseudomembranous colitis and life-threatening fulminant colitis, which may result in death. Prompt identification of patients with symptomatic Clostridium difficile infection is essential as the majority of patients respond quickly to antimicrobial therapy. Prevention is best accomplished by implementation of infection-control measures and by judicious use of antimicrobial agents.

Genetic relatedness between Japanese and European isolates of Clostridium difficile originating from piglets and their risk associated with human health

Clostridium difficile colonization in pig intestine has been a public health concern. We analyzed C. difficile prevalence among piglets in Japan to clarify their origin and extent of the associated risk by using molecular and microbiological methods for both swine and human clinical isolates and foreign isolates. C. difficile was isolated from 120 neonatal piglet fecal samples. Toxin gene profile, antimicrobial susceptibilities, PCR ribotype, and multiple-locus variable-number tandem-repeat analysis (MLVA) type of swine isolates were determined and compared with those of human clinical and foreign isolates. One-hundred C. difficile strains were isolated from 69 (57.5%) samples, and 61 isolates (61%) were toxin gene-positive. Some isolates were resistant to antimicrobials, contributing to antibiotic-associated diarrhea by C. difficile. These results suggest that C. difficile, prevalent among Japanese pigs, is a potential risk for antibiotic-associated diarrhea. Furthermore, PCR ribotype 078 (12 isolates), which has been linked to multiple outbreaks worldwide, was the third-most frequently isolated of the 14 PCR ribotypes identified. Moreover, MLVA revealed that all 12 PCR ribotype 078 isolates were genetically related to European PCR ribotype 078 strains found in both humans and pigs. To date, in Japan, many breeding pigs have been imported from European countries. The genetic relatedness of C. difficile isolates of Japanese swine origin to those of European origin suggests that they were introduced into Japan via imported pigs.

Clostridium difficile infection in diabetes

Diabetes-related hospitalization and hospital utilization is a serious challenge to the health care system, a situation which may be further aggravated by nosocomial Clostridium difficile (C. difficile) infection (CDI). Studies have demonstrated that diabetes increases the risk of recurrent CDI with OR (95% CI) 2.99 (1.88, 4.76). C. difficile is a gram-positive, spore-forming anaerobic bacterium which is widely distributed in the environment. Up to 7% of healthy adults and up to 45% of infants may have asymptomatic intestinal carriage of C. difficile. A large number of strains of C. difficile have been identified. A number of PCR or sequence-based molecular typing methods are available for typing C. difficile isolates. C. difficile virulence evolved independently in the highly epidemic lineages, associated with the expression of toxin genes and other virulence factors. This article briefly reviews recent progresses in the bateriology of C. difficile and highlights the limited knowledge of potential mechanisms for the increased risk of CDI in diabetes which warrants further research.

Clinical characteristics of relapses and re-infections in Clostridium difficile infection

The purpose of this study was to identify factors associated with relapses or re-infections in patients with recurring Clostridium difficile infections (CDIs). From September 2008 to January 2012, cases with two or more isolates from consecutive CDI episodes were included. PCR-ribotyping and multilocus variable-number tandem-repeat analysis were performed using paired isolates. Among 473 patients, 68 (14.4%) experienced one to five recurrences. Fifty-one of these with two or more isolates from consecutive CDI episodes were included in the study; 25 (49%) were classified as relapses and 26 (51%) as re-infections. Recurrence interval was shorter in the relapse group (26.0 versus 67.5 p 0.001), but more patients in the re-infection group were hospitalized during recurrence interval (53.8% versus 8.0%, p<0.001). Relapse rates in infections by ribotype 017, ribotype 018 and other ribotypes were 63.6%, 63.6% and 22.2%, respectively (p 0.274, p 0.069, and p 0.005). In multivariate logistic regression, infections by ribotypes 017 and 018 were associated with CDI relapse (OR 4.77, 95% CI 1.02-22.31, p 0.047; OR 11.49, 95% CI 2.07-63.72, p 0.005). Conversely, admission during recurrence interval lowered the risk of relapse (OR 0.044, 95% CI 0.006-0.344, p 0.003). In conclusion, relapse was more likely when infection was caused by PCR ribotypes 017 and 018.

C. difficile ribotype 027 or 176?

Clostridium difficile is a major nosocomial pathogen of present times. The analysis of 624 C. difficile strains from 11 hospitals in the Czech Republic in 2013 revealed that 40% of isolates belonged to ribotype 176. These results suggest that the incidence of CDI (C. difficile infection) in the Czech Republic has increased probably in connection with C. difficile ribotype 176. The molecular systems Xpert C. difficile Epi assay (Cepheid Inc., Sunnyvale, CA) diagnoses toxigenic strains and supports C. difficile ribotype 027 determination based on three specific target places in the toxigenic C. difficile genome. Twenty-nine strains cultivated from stool specimens were evaluated by the Xpert systems as presumed C. difficile PCR ribotype 027 were confirmed as a C. difficile ribotype 176 based on ribotyping. A further 120 C. difficile strains of ribotype 176 were examined for the presence of genes tcdB, cdtB and deletion in position 117 in the tcdC gene. Our experience shows that due to the correspondence of the target places, C. difficile ribotype 176 may be interpreted as ribotype 027 by Xpert C. difficile Epi assay (Cepheid Inc., Sunnyvale, CA). Further molecular analysis as ribotyping based on capillary electrophoresis is needed to differentiate between C. difficile ribotypes 027 and 176 for appropriate epidemiological situation control on local and national levels.

NAP1 strain type predicts outcomes from Clostridium difficile infection

BACKGROUND

Studies are conflicting regarding the importance of the fluoroquinolone-resistant North American pulsed-field gel electrophoresis type 1 (NAP1) strain in Clostridium difficile infection (CDI) outcome. We describe strain types causing CDI and evaluate their association with patient outcomes.

METHODS

CDI cases were identified from population-based surveillance. Multivariate regression models were used to evaluate the associations of strain type with severe disease (ileus, toxic megacolon, or pseudomembranous colitis within 5 days; or white blood cell count ≥15 000 cells/µL within 1 day of positive test), severe outcome (intensive care unit admission after positive test, colectomy for C. difficile infection, or death within 30 days of positive test), and death within 14 days of positive test.

RESULTS

Strain typing results were available for 2057 cases. Severe disease occurred in 363 (17.7%) cases, severe outcome in 100 (4.9%), and death within 14 days in 56 (2.7%). The most common strain types were NAP1 (28.4%), NAP4 (10.2%), and NAP11 (9.1%). In unadjusted analysis, NAP1 was associated with greater odds of severe disease than other strains. After controlling for patient risk factors, healthcare exposure, and antibiotic use, NAP1 was associated with severe disease (adjusted odds ratio [AOR], 1.74; 95% confidence interval [CI], 1.36-2.22), severe outcome (AOR, 1.66; 95% CI, 1.09-2.54), and death within 14 days (AOR, 2.12; 95% CI, 1.22-3.68).

CONCLUSIONS

NAP1 was the most prevalent strain and a predictor of severe disease, severe outcome, and death. Strategies to reduce NAP1 prevalence, such as antibiotic stewardship to reduce fluoroquinolone use, might reduce CDI morbidity.

Investigation of potentially pathogenic Clostridium difficile contamination in household environs

As Clostridium difficile spores are resistant to many household cleaning products, the potential for community household contamination is high. The purpose of this study was to assess the prevalence of toxigenic C. difficile from environmental sources from a large urban area. Three to 5 household items or environmental dust was collected from 30 houses in Houston, Texas. A total of 127 environmental samples were collected from shoe bottoms (n = 63), bathroom surfaces (n = 15), house floor dusts (n = 12), or other household surfaces (n = 37). Forty one of 127 samples (32.3%) grew C. difficile. All 41 isolates were positive for toxin A and B genes and no isolate was positive for binary toxin genes. Shoe bottom swab samples had the highest percent of positive samples (25/63; 39.7%) followed by bathroom/toilet surfaces (5/15; 33.3%), house floor dust (4/12; 33.3%), and other surface swabs (7/37; 18.9%). Strains were grouped into 25 different ribotypes, the most prevalent type was 001 (5 strains). In conclusion, a high rate of environmental contamination of C. difficile was observed from community households from a large urban area.

The systemic inflammatory response to Clostridium difficile infection

Background

The systemic inflammatory response to Clostridium difficile infection (CDI) is incompletely defined, particularly for patients with severe disease.

Methods

Analysis of 315 blood samples from 78 inpatients with CDI (cases), 100 inpatients with diarrhea without CDI (inpatient controls), and 137 asymptomatic outpatient controls without CDI was performed. Serum or plasma was obtained from subjects at the time of CDI testing or shortly thereafter. Severe cases had intensive care unit admission, colectomy, or death due to CDI within 30 days after diagnosis. Thirty different circulating inflammatory mediators were quantified using an antibody-linked bead array. Principal component analysis (PCA), multivariate analysis of variance (MANOVA), and logistic regression were used for analysis.

Results

Based on MANOVA, cases had a significantly different inflammatory profile from outpatient controls but not from inpatient controls. In logistic regression, only chemokine (C-C motif) ligand 5 (CCL5) levels were associated with cases vs. inpatient controls. Several mediators were associated with cases vs. outpatient controls, especially hepatocyte growth factor, CCL5, and epithelial growth factor (inversely associated). Eight cases were severe and associated with elevations in IL-8, IL-6, and eotaxin.

Conclusions

A broad systemic inflammatory response occurs during CDI and severe cases appear to differ from non-severe infections.

A novel subtyping assay for detection of Clostridium difficile virulence genes

This proof-of-concept study demonstrates the application of a novel nucleic acid detection platform to detect Clostridium difficile in subjects presenting with acute diarrheal symptoms. This method amplifies three genes associated with C. difficile infection, including genes and deletions (cdtB and tcdC) associated with hypervirulence attributed to the NAP1/027/BI strain. Amplification of DNA from the tcdB, tcdC, and cdtB genes was performed using a droplet-based sandwich platform with quantitative real-time PCR in microliter droplets to detect and identify the amplified fragments of DNA. The device and identification system are simple in design and can be integrated as a point-of-care test to help rapidly detect and identify C. difficile strains that pose significant health threats in hospitals and other health-care communities.

The incidence and clinical symptomatology of Clostridium difficile infections in a community setting in a cohort of Danish patients attending general practice

Clostridium difficile infection (CDI) is gradually being recognised as a cause of morbidity in the community. We investigated the incidence and clinical characteristics of CDI in a community setting and characterised the C. difficile strains by toxin gene profiling and polymerase chain reaction (PCR) ribotyping. Patients included in the study had attended general practice, primarily because of diarrhoea; CDI patients (259 patients; 121 <2 years of age) had positive cultures for toxigenic C. difficile and non-CDI patients (455 patients) were culture-negative. Outcome variables included the frequency and duration of diarrhoea, vomiting, stomach ache, fever >38 °C, weight loss and sick leave. Data were analysed by logistic regression. CDI patients <2 and ≥2 years of age with C. difficile as the only enteropathogen in the faecal sample reported slimy stools (65% vs. 62%), stomach ache (60% vs. 75%), weight loss (50% vs. 76%) and duration of diarrhoea >15 days (59% vs. 73%) as the predominant symptoms. CDI patients ≥2 years old reported duration of diarrhoea >15 days more often compared to non-CDI patients (73% vs. 27 %, p < 0.0001). The annual incidence of CDI was 518 and 23/100,000 for patients <2 and ≥2 years of age, respectively, and 46/100,000 in the subgroup of patients ≥60 years of age. CDI was characterised by stomach ache and persistent diarrhoea, often leading to weight loss. This emphasises the importance of diagnosing CDI not only in hospitalised patients, but also in individuals ≥2 years of age attending general practice because of gastrointestinal symptoms, especially in the elderly, where the incidence of CDI is high.

Phage ϕC2 mediates transduction of Tn6215, encoding erythromycin resistance, between Clostridium difficile strains

In this work, we show that Clostridium difficile phage ϕC2 transduces erm(B), which confers erythromycin resistance, from a donor to a recipient strain at a frequency of 10⁻⁶ per PFU. The transductants were lysogenic for ϕC2 and contained the erm(B) gene in a novel transposon, Tn6215. This element is 13,008 bp in length and contains 17 putative open reading frames (ORFs). It could also be transferred at a lower frequency by filter mating.

Clostridium difficile is a major human pathogen that causes diarrhea that can be persistent and difficult to resolve using antibiotics. C. difficile is potentially zoonotic and has been detected in animals, food, and environmental samples. C. difficile genomes contain large portions of horizontally acquired genetic elements. The conjugative elements have been reasonably well studied, but transduction has not yet been demonstrated. Here, we show for the first time transduction as a mechanism for the transfer of a novel genetic element in C. difficile. Transduction may also be a useful tool for the genetic manipulation of C. difficile.

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.

Risk factors for Clostridium difficile infection in the community: a case-control study in patients in general practice, Denmark, 2009-2011

To identify risk factors for Clostridium difficile infection (CDI) in Danish patients consulting general practice with gastrointestinal symptoms, a prospective matched case-control study was performed; cases (N = 259) had positive cultures for toxigenic C. difficile and controls (N = 455) negative cultures. Data were analysed by conditional logistic regression. In patients aged ⩾2 years (138 cases), hospitalization [odds ratio (OR) 8·4, 95% confidence interval (CI) 3·1-23], consumption of beef (OR 5·5, 95% CI 2·0-15), phenoxymethylpenicillin (OR 15, 95% CI 2·7-82), dicloxacillin (OR 27, 95% CI 3·6-211), and extended spectrum penicillins (OR 9·2, 95% CI 1·9-45) were associated with CDI. In patients aged <2 years none of these were associated with CDI, but in a subgroup analysis contact with animals was associated with CDI (OR 8·1, 95% CI 1·0-64). This study emphasizes narrow-spectrum penicillins, and suggests beef consumption, as risk factors for CDI in adults, and indicates a different epidemiology of CDI in infants.

First case of autochthonous Clostridium difficile PCR ribotype 027 detected in Spain

INTRODUCTION

Clostridium difficile ribotype 027 (Cd027) has caused outbreaks in the United States, Canada, and Europe since 2001. In Spain, the importance of Cd027 is still unknown. In 2007, we began active surveillance of Cd027 to determine its incidence in our hospital.

METHODS

From January 2007 to April 2012, isolates of C. difficile by multiplex PCR were studied to detect toxin genes. Binary toxin-positive isolates were characterized using PCR-ribotyping. Cd027 were further characterized by toxino-typing, sequencing of tcdC gene, and MLVA (multilocus-variable-number-tandem-repeat-analysis).

RESULTS

Only 8 strains were Cd027 from 3666 isolates of C. difficile analyzed during the study period. These strains were isolated from 4 patients: a Spanish patient previously hospitalized in the UK, a pregnant laboratory technician, a British tourist, and a Spanish patient without epidemiological antecedents for acquiring Cd027. MLVA typing of Cd027 isolates revealed 4 different patterns. The first patient had 2 episodes of diarrhea caused by different Cd027. The strains from the first episode of patient 1 and the strain from patient 2 were grouped in the same clonal cluster (these cases were previously published as laboratory transmission), while strains from patients 3 and 4 were genetically unrelated to each other, and to the strains from patients 1 and 2.

CONCLUSION

We report the first finding of an autochthonous case of non-severe Cd027 infection. Our results indicate that Cd027 diarrhea is uncommon in our area, and it appears mainly as imported cases. MLVA typing enables us to distinguish different genotypes among our Cd027 isolates.

Detection of mixed populations of Clostridium difficile from symptomatic patients using capillary-based polymerase chain reaction ribotyping

OBJECTIVE

To investigate the simultaneous occurrence of more than 1 Clostridium difficile ribotype in patients' stool samples at the time of diagnostic testing.

METHODS

Stool samples submitted for diagnostic testing for the presence of toxigenic C. difficile were obtained for 102 unique patients. A total of 95 single colonies of C. difficile per stool sample were isolated on selective media, subcultured alongside negative (uninoculated) controls, and polymerase chain reaction (PCR) ribotyped using capillary gel electrophoresis.

RESULTS

Capillary-based PCR ribotyping was successful for 9,335 C. difficile isolates, yielding a median of 93 characterized isolates per stool sample (range, 69-95). More than 1 C. difficile ribotype was present in 16 of 102 (16%) C. difficile infection (CDI) cases; 2 of the 16 mixtures were composed of at least 3 ribotypes, while the remaining 14 were composed of at least 2.

CONCLUSIONS

Deep sampling of patient stool samples coupled with capillary-based PCR ribotyping identified a high rate of mixed CDI cases compared with previous estimates. Studies seeking to quantify the clinical significance of particular C. difficile ribotypes should account for mixed cases of disease.

Clostridium difficile ribotype diversity at six health care institutions in the United States

Capillary-based PCR ribotyping was used to quantify the presence/absence and relative abundance of 98 Clostridium difficile ribotypes from clinical cases of disease at health care institutions in six states of the United States. Regionally important ribotypes were identified, and institutions in close proximity did not necessarily share more ribotype diversity than institutions that were farther apart.