In 2009 the first European Society of Clinical Microbiology and Infectious Diseases (ESCMID) guideline for diagnosing Clostridium difficile infection (CDI) was launched. Since then newer tests for diagnosing CDI have become available, especially nucleic acid amplification tests. The main objectives of this update of the guidance document are to summarize the currently available evidence concerning laboratory diagnosis of CDI and to formulate and revise recommendations to optimize CDI testing. This update is essential to improve the diagnosis of CDI and to improve uniformity in CDI diagnosis for surveillance purposes among Europe. An electronic search for literature concerning the laboratory diagnosis of CDI was performed. Studies evaluating a commercial laboratory test compared to a reference test were also included in a meta-analysis. The commercial tests that were evaluated included enzyme immunoassays (EIAs) detecting glutamate dehydrogenase, EIAs detecting toxins A and B and nucleic acid amplification tests. Recommendations were formulated by an executive committee, and the strength of recommendations and quality of evidence were graded using the Grades of Recommendation Assessment, Development and Evaluation (GRADE) system. No single commercial test can be used as a stand-alone test for diagnosing CDI as a result of inadequate positive predictive values at low CDI prevalence. Therefore, the use of a two-step algorithm is recommended. Samples without free toxin detected by toxins A and B EIA but with positive glutamate dehydrogenase EIA, nucleic acid amplification test or toxigenic culture results need clinical evaluation to discern CDI from asymptomatic carriage.

Background: Variations in testing for Clostridium difficile infection (CDI) may hinder patient care, increase

The catabolite control protein CcpA is a pleiotropic regulator that mediates the global transcriptional response to rapidly catabolizable carbohydrates, like glucose in Gram-positive bacteria. By whole transcriptome analyses, we characterized glucose-dependent and CcpA-dependent gene regulation in Clostridium difficile. About 18% of all C. difficile genes are regulated by glucose, for which 50% depend on CcpA for regulation. The CcpA regulon comprises genes involved in sugar uptake, fermentation and amino acids metabolism, confirming the role of CcpA as a link between carbon and nitrogen pathways. Using combination of chromatin immunoprecipitation and genome sequence analysis, we detected 55 CcpA binding sites corresponding to ∼140 genes directly controlled by CcpA. We defined the C. difficile CcpA consensus binding site (creCD motif), that is, ‘RRGAAAANGTTTTCWW’. Binding of purified CcpA protein to 19 target creCD sites was demonstrated by electrophoretic mobility shift assay. CcpA also directly represses key factors in early steps of sporulation (Spo0A and SigF). Furthermore, the C. difficile toxin genes (tcdA and tcdB) and their regulators (tcdR and tcdC) are direct CcpA targets. Finally, CcpA controls a complex and extended regulatory network through the modulation of a large set of regulators.

A 2-month prospective study of Clostridium difficile infections was conducted in 38 hospitals from 14 different European countries in order to obtain an overview of the phenotypic and genotypic features of clinical isolates of C. difficile during 2005. Of 411 isolates from diarrhoeagenic patients with suspected C. difficile-associated diarrhoea (CDAD), 354 were toxigenic, of which 86 (24.3%) were toxin-variant strains. Major toxinotypes included toxinotypes 0 (n = 268), V (n = 28), VIII (n = 22) and III (n = 25). MICs of metronidazole, vancomycin, erythromycin, clindamycin, moxifloxacin and tetracycline were determined using the Etest method. All the toxigenic strains were fully-susceptible to metronidazole and vancomycin. Resistance to erythromycin, clindamycin, tetracycline and moxifloxacin was found in 44.4%, 46.1%, 9.2% and 37.5% of the isolates, respectively. Sixty-six different PCR ribotypes were characterised, with the 027 epidemic strain accounting for 6.2% of isolates. This strain was positive for binary toxin genes, had an 18-bp deletion in the tcdC gene, and was resistant to both erythromycin and moxifloxacin. The mean incidence of CDAD was 2.45 cases/10 000 patient-days, but this figure varied widely among the participating hospitals. Patients infected with the 027 strain were more likely to have a severe disease (OR 3.29, 95% CI 1.19-9.16, p 0.008) and to have been specifically treated with metronidazole or vancomycin (OR 7.46, 95% CI 1.02-154, p 0.02). Ongoing epidemiological surveillance of cases of CDAD, with periodic characterisation of the strains involved, is required to detect clustering of cases in time and space and to monitor the emergence of specific highly virulent clones.

Clostridium difficile is responsible for 15-25% of cases of antibiotic-associated diarrhea (AAD) and for virtually all cases of antibiotic-associated pseudomembranous colitis (PMC). This anaerobic bacterium has been identified as the leading cause of nosocomial infectious diarrhea in adults and can be responsible for large outbreaks. Nosocomial C. difficile infection results in an increased length of stay in hospital ranging from 8 to 21 days. Risk factors for C. difficile-associated diarrhea include antimicrobial therapy, older age (>65 years), antineoplastic chemotherapy and length of hospital stay. Other interventions with high risk associations are enemas, nasogastric tubes, gastrointestinal surgery and antiperistaltic drugs. Prospective studies have shown that nosocomial transmission of C. difficile is frequent but often remains asymptomatic. Patients can be contaminated from environmental surfaces, shared instrumentation, hospital personnel hands and infected roommates. Once an outbreak starts, C. difficile may be spread rapidly throughout the hospital environment where spores may persist for months. Measures that are effective in reducing incidence of C. difficile infections and cross-infection include: (i) an accurate and rapid diagnosis, (ii) appropriate treatment, (iii) implementation of enteric precautions for symptomatic patients, (iv) reinforcement of hand-washing, (v) daily environmental disinfection, and (vi) a restrictive antibiotic policy. C. difficile is a common cause of infectious diarrhea and should be therefore systematically investigated in patients with nosocomial diarrhea.

Recent outbreaks of Clostridium difficile-associated diarrhoea (CDAD) with increased severity, high relapse rate and significant mortality have been related to the emergence of a new, hypervirulent C. difficile strain in North America, Japan and Europe. Definitions have been proposed by the European Centre of Disease Prevention and Control (ECDC) to identify severe cases of CDAD and to differentiate community-acquired cases from nosocomial CDAD (http://www.ecdc.europa.eu/documents/pdf/Cl_dif_v2.pdf). CDAD is mainly known as a healthcare-associated disease, but it is also increasingly recognised as a community-associated disease. The emerging strain is referred to as North American pulsed-field type 1 (NAP1) and PCR ribotype 027. Since 2005, individual countries have developed surveillance studies to monitor the spread of this strain. C. difficile type 027 has caused outbreaks in England and Wales, Ireland, the Netherlands, Belgium, Luxembourg, and France, and has also been detected in Austria, Scotland, Switzerland, Poland and Denmark. Preliminary data indicated that type 027 was already present in historical isolates collected in Sweden between 1997 and 2001.

Clostridium difficile-associated diarrhoea (CDAD) presents mainly as a nosocomial infection, usually after antimicrobial therapy. Many outbreaks have been attributed to C. difficile, some due to a new hyper-virulent strain that may cause more severe disease and a worse patient outcome. As a result of CDAD, large numbers of C. difficile spores may be excreted by affected patients. Spores then survive for months in the environment; they cannot be destroyed by standard alcohol-based hand disinfection, and persist despite usual environmental cleaning agents. All these factors increase the risk of C. difficile transmission. Once CDAD is diagnosed in a patient, immediate implementation of appropriate infection control measures is mandatory in order to prevent further spread within the hospital. The quality and quantity of antibiotic prescribing should be reviewed to minimise the selective pressure for CDAD. This article provides a review of the literature that can be used for evidence-based guidelines to limit the spread of C. difficile. These include early diagnosis of CDAD, surveillance of CDAD cases, education of staff, appropriate use of isolation precautions, hand hygiene, protective clothing, environmental cleaning and cleaning of medical equipment, good antibiotic stewardship, and specific measures during outbreaks. Existing local protocols and practices for the control of C. difficile should be carefully reviewed and modified if necessary.

f Clostridium difficile is currently the major cause of nosocomial intestinal diseases associated with antibiotic therapy in adults. In order to improve our knowledge of C. difficile-host interactions, we analyzed the genome-wide temporal expression of C. difficile 630 genes during the first 38 h of mouse colonization to identify genes whose expression is modulated in vivo, suggesting that they may play a role in facilitating the colonization process. In the ceca of the C. difficile-monoassociated mice, 549 genes of the C. difficile genome were differentially expressed compared to their expression during in vitro growth, and they were distributed in several functional categories. Overall, our results emphasize the roles of genes involved in host adaptation. Colonization results in a metabolic shift, with genes responsible for the fermentation as well as several other metabolic pathways being regulated inversely to those involved in carbon metabolism. In addition, several genes involved in stress responses, such as ferrous iron uptake or the response to oxidative stress, were regulated in vivo. Interestingly, many genes encoding conserved hypothetical proteins (CHP) were highly and specifically upregulated in vivo. Moreover, genes for all stages of sporulation were quickly induced in vivo, highlighting the observation that sporulation is central to the persistence of C. difficile in the gut and to its ability to spread in the environment. Finally, we inactivated two genes that were differentially expressed in vivo and evaluated the relative colonization fitness of the wild-type and mutant strains in coinfection experiments. We identified a CHP as a putative colonization factor, supporting the suggestion that the in vivo transcriptomic approach can unravel new C. difficile virulence genes.