Variations in testing for Clostridium difficile infection can hinder patients' care, increase the risk of transmission, and skew epidemiological data. We aimed to measure the underdiagnosis of C difficile infection across Europe. We did a questionnaire-based study at 482 participating hospitals across 20 European countries. Hospitals were questioned about their methods and testing policy for C difficile infection during the periods September, 2011, to August, 2012, and September, 2012, to August, 2013. On one day in winter, 2012-13 (December, 2012, or January, 2013), and summer, 2013 (July or August), every hospital sent all diarrhoeal samples submitted to their microbiology laboratory to a national coordinating laboratory for standardised testing of C difficile infection. Our primary outcome measures were the rates of testing for and cases of C difficile infection per 10 000 patient bed-days. Results of local and national C difficile infection testing were compared with each other. If the result was positive at the national laboratory but negative at the local hospital, the result was classified as undiagnosed C difficile infection. We compared differences in proportions with the Mann-Whitney test, or McNemar's test if data were matched. During the study period, participating hospitals reported a mean of 65·8 tests (country range 4·6-223·3) for C difficile infection per 10 000 patient-bed days and a mean of 7·0 cases (country range 0·7-28·7) of C difficile infection per 10 000 patient-bed days. Only two-fifths of hospitals reported using optimum methods for testing of C difficile infection (defined by European guidelines), although the number of participating hospitals using optimum methods increased during the study period, from 152 (32%) of 468 in 2011-12 to 205 (48%) of 428 in 2012-13. Across all 482 European hospitals on the two sampling days, 148 (23%) of 641 samples positive for C difficile infection (as determined by the national laboratory) were not diagnosed by participating hospitals because of an absence of clinical suspicion, equating to about 74 missed diagnoses per day. A wide variety of testing strategies for C difficile infection are used across Europe. Absence of clinical suspicion and suboptimum laboratory diagnostic methods mean that an estimated 40 000 inpatients with C difficile infection are potentially undiagnosed every year in 482 European hospitals. Astellas Pharmaceuticals Europe.

Multidrug resistance and antibiotic resistance mechanisms were investigated in 316 Clostridium difficile clinical isolates collected during the first European surveillance on C. difficile in 2005. MICs of eight different antibiotics were determined using Etest. Reserpine- and carbonyl cyanide m-chlorophenylhydrazone-sensitive efflux was tested using the agar dilution method. Molecular analysis of the resistance mechanisms was performed using PCR assays, PCR mapping and sequencing. One hundred and forty-eight C. difficile strains were resistant to at least one antibiotic and 82 (55%) were multidrug resistant. In particular, 48% of these isolates were resistant to erythromycin, clindamycin, moxifloxacin and rifampicin. New genetic elements or determinants conferring resistance to erythromycin/clindamycin or tetracycline were identified. Even if most multiresistant strains carried an erm(B) gene, quite a few were erm(B) negative. In-depth analysis of the underlying mechanism in these isolates was carried out, including analysis of 23S rDNA and the ribosomal proteins L4 and L22. Interestingly, resistance to rifampicin was observed in multidrug-resistant strains in association with resistance to fluoroquinolones. Mutations in the rpo(B) and gyrA genes were identified as the cause of resistance to these antibiotics, respectively. Characterization of multidrug-resistant C. difficile clinical isolates shows that antibiotic resistance is changing, involving new determinants and mechanisms and providing this pathogen with potential advantages over the co-resident gut flora. The present paper provides, for the first time, a comprehensive picture of the different characteristics of multidrug-resistant C. difficile strains in Europe in 2005 and represents an important source of data for future comparative European studies.

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.

Biofilms are complex, highly organized structures formed by microorganisms, with functional cell arrangements that allow for intricate communication. Severe clinical challenges occur when anaerobic bacterial species establish long-lasting infections, especially those involving biofilms. These infections can occur in device-related settings (e.g., implants) as well as in non-device-related conditions (e.g., inflammatory bowel disease). Within biofilms, bacterial cells communicate by producing and detecting extracellular signals, particularly through specific small signaling molecules known as autoinducers. These quorum-sensing signals are crucial in all steps of biofilm formation: initial adhesion, maturation, and dispersion, triggering gene expression that coordinates bacterial virulence factors, stimulates immune responses in host tissues, and contributes to antibiotic resistance development. Within anaerobic biofilms, bacteria communicate via quorum-sensing molecules such as N-Acyl homoserine lactones (AHLs), autoinducer-2 (AI-2), and antimicrobial molecules (autoinducing peptides, AIPs). To effectively combat pathogenic biofilms, understanding biofilm formation mechanisms and bacterial interactions is essential. The strategy to disrupt quorum sensing, termed quorum quenching, involves methods like inactivating or enzymatically degrading signaling molecules, competing with signaling molecules for binding sites, or noncompetitively binding to receptors, and blocking signal transduction pathways. In this review, we comprehensively analyzed the fundamental molecular mechanisms of quorum sensing in biofilms formed by anaerobic bacteria. We also highlight quorum quenching as a promising strategy to manage bacterial infections associated with anaerobic bacterial biofilms.