Gastrointestinal disorders and the critically ill. Clostridium difficile infection and pseudomembranous colitis

Overview of current detection methods and microRNA potential in Clostridioides difficile infection screening

Clostridioides difficile (formerly called Clostridium difficile, C. difficile) infection (CDI) is listed as an urgent threat on the 2019 antibiotic resistance threats report in the United States by the Centers for Disease Control and Prevention. Early detection and appropriate disease management appear to be essential. Meanwhile, although the majority of cases are hospital-acquired CDI, community-acquired CDI cases are also on the rise, and this vulnerability is not limited to immunocompromised patients. Gastrointestinal treatments and/or gastrointestinal tract surgeries may be required for patients diagnosed with digestive diseases. Such treatments could suppress or interfere with the patient’s immune system and disrupt gut flora homeostasis, creating a suitable microecosystem for C. difficile overgrowth. Currently, stool-based non-invasive screening is the first-line approach to CDI diagnosis, but the accuracy is varied due to different clinical microbiology detection methods; therefore, improving reliability is clearly required. In this review, we briefly summarised the life cycle and toxicity of C. difficile, and we examined existing diagnostic approaches with an emphasis on novel biomarkers such as microRNAs. These biomarkers can be easily detected through non-invasive liquid biopsy and can yield crucial information about ongoing pathological phenomena, particularly in CDI.

Clostridioides difficile Infection in a Japanese Tertiary Children's Hospital

PURPOSE

Toxins produced by Clostridioides difficile infection (CDI) can cause enteritis and diarrhea. Although the number of pediatric CDI cases is increasing, the clinical management of pediatric CDI, including patient characteristics and prognosis, remains unclear. This study aimed to elucidate the background and clinical course of patients with CDI and evaluate the reliability of diagnostic tests in a tertiary pediatric hospital in Japan.

METHODS

We retrospectively analyzed the clinical data of children diagnosed with CDI between 2011 and 2021 at the Saitama Children's Medical Center in Saitama, Japan.

RESULTS

During the study period, 1,252 C. difficile antigen/toxin tests were performed, and 37 patients were diagnosed with CDI. The main underlying diseases among the patients were hematological and malignant disorders and gastrointestinal diseases, including inflammatory bowel disease (IBD) (59.4%). Two patients (5.4%) had an unremarkable medical history. Among the 37 patients, 27 (73.0%) were immunocompromised, 25 (67.6%) had a history of antibiotic use within the past two months, and 6 (16.2%) were negative on the initial test but were positive on the second test. Finally, 28 patients (75.7%) required primary antibiotic therapy only, and two patients with IBD required additional antibiotic therapy as secondary treatment.

CONCLUSION

The number of pediatric patients with CDI is increasing. Both a comprehensive interview, including underlying diseases and history of antibiotic use, and an understanding of the features of clinical examinations should be emphasized to appropriately diagnose and treat CDI.

Impact of a phage cocktail targeting Escherichia coli and Enterococcus faecalis as members of a gut bacterial consortium in vitro and in vivo

Escherichia coli and Enterococcus faecalis have been implicated as important players in human gut health that have been associated with the onset of inflammatory bowel disease (IBD). Bacteriophage (phage) therapy has been used for decades to target pathogens as an alternative to antibiotics, but the ability of phage to shape complex bacterial consortia in the lower gastrointestinal tract is not clearly understood. We administered a cocktail of six phages (either viable or heat-inactivated) targeting pro-inflammatory Escherichia coli LF82 and Enterococcus faecalis OG1RF as members of a defined community in both a continuous fermenter and a murine colitis model. The two target strains were members of a six species simplified human microbiome consortium (SIHUMI-6). In a 72-h continuous fermentation, the phage cocktail caused a 1.1 and 1.5 log (log10 genome copies/mL) reduction in E. faecalis and E. coli numbers, respectively. This interaction was accompanied by changes in the numbers of other SIHUMI-6 members, with an increase of Lactiplantibacillus plantarum (1.7 log) and Faecalibacterium prausnitzii (1.8 log). However, in germ-free mice colonized by the same bacterial consortium, the same phage cocktail administered twice a week over nine weeks did not cause a significant reduction of the target strains. Mice treated with active or inactive phage had similar levels of pro-inflammatory cytokines (IFN-y/IL12p40) in unstimulated colorectal colonic strip cultures. However, histology scores of the murine lower GIT (cecum and distal colon) were lower in the viable phage-treated mice, suggesting that the phage cocktail did influence the functionality of the SIHUMI-6 consortium. For this study, we conclude that the observed potential of phages to reduce host populations in in vitro models did not translate to a similar outcome in an in vivo setting, with this effect likely brought about by the reduction of phage numbers during transit of the mouse GIT.

Increased clostridium difficile infection in the era of preoperative chemotherapy for pancreatic cancer

BACKGROUND

In recent trend of preoperative chemotherapy, postoperative clostridium difficile infection (CDI) might be increasing in pancreatic ductal adenocarcinoma (PDAC) patients. This study aimed to elucidate the inducement of postoperative CDI in the new era of preoperative chemotherapy.

METHODS

Eligible patients were those who received pancreaticoduodenectomy for PDAC. Patients were classified into two groups according to the presence or absence of postoperative CDI, and the independently associated factors for postoperative CDI were investigated. Additionally, eligible patients were classified using the identified associated factors, and the duration of preoperative antimicrobial administration and incidence of CDI were compared between the groups.

RESULTS

Two hundred PDAC patients were eligible for this study, and postoperative CDI was detected in 15 (7.5%) patients. Multivariate analysis revealed that preoperative biliary tract infection (BTI) and chemotherapy (Chemo) were independently associated with postoperative CDI (OR, 4.05; 95% CI, 1.25-13.1; p = 0.0200 and OR, 3.64; 95% CI, 1.14-11.6; p = 0.0209, respectively). The patients were classified into four groups according to the presence or absence of preoperative BTI and Chemo (BTI-/Chemo-, BTI-/Chemo+, BTI+/Chemo- and BTI+/Chemo + group). The median durations of preoperative antimicrobial administration were 0, 2, 8 and 15 days in each group, respectively. Postoperative CDI was detected in 3.7%, 10.0%, 10.5% and 31.3% in each group, respectively, and patients in BTI+/Chemo + group suffered CDI more frequently compared to those in BTI-/Chemo-group (p = 0.00778).

CONCLUSIONS

Preoperative BTI and chemotherapy might induce postoperative CDI for PDAC patients.

Histopathology of non-IBD colitis practical recommendations from pathologists of IG-IBD Group

Pathologists are often called upon to diagnose colitides that differ from the two main forms of inflammatory bowel disease (IBD). These non-IBD colitides include infectious colitis, microscopic colitis, ischemic colitis, eosinophilic colitis, autoimmune enterocolitis, segmental colitis associated with diverticulosis, drug-induced colitis, radiation colitis and diversion colitis. The diagnosis of these different disease entities relies on the histopathological examination of endoscopic biopsies of the gastrointestinal tract. This paper reviews the main histomorphological characteristics of the various Non-IBD colitides.

Evaluation of recreational risks due to exposure of antibiotic-resistance bacteria from environmental water: A proposed framework

This research provides a framework for the human health risk assessment due to exposure of AR (antibiotic resistance) E. coli from recreational water (swimming activity). Literature-based epidemiological studies were used for f-value formulation (i.e., AR E. coli/total number of E. coli isolates) and the theoretical calculation of AR and non-AR E. coli concentrations. Risk was estimated using calculated values by considering four different dose-response (D-R) scenarios with known characteristics due to current lack of availability of D-R for AR bacteria. f-values ranged between 0.14 and 0.59 and the order of calculated theoretical values of maximum AR E. coli are as follows: ampicillin or amoxicillin (38 CFU/dip) > co-trimoxazole (19 CFU/dip) ~ tetracycline (18 CFU/dip) > ceftriaxone or cefotaxime or ceftazidime (10 CFU/dip) ~ ciprofloxacin or ofloxacin (9 CFU/dip). The risk of infection was considerably high for theoretical calculated concentration values regardless of the chosen D-R model (annual risk of infection (95th percentile) = 1, Spearman's rank correlation coefficient = -0.06 to 0.94), under the conditions studied. Further, AR levels of human gastrointestinal-tract were determined using literature-reported data in stool samples and indicated that the resistance level was very high in healthy human (range: 3.7 × 10⁷-8.4 × 10⁷ CFU/g of wet lumen content). The maximum allowable concentration values for AR E. coli and non-ARB (0.0075 CFU/dip and 2.56 CFU/dip) were found to be smaller than the USEPA recreational water quality guidelines (≤126 CFU/100 mL), which can help the USEPA and other regulatory bodies in revisiting the current guidelines. So based on the noted results, we can conclude that the maintenance of inventory of actual measured concentration of ARB in the recreational water sites is needed to prevent unwanted complication related to the treatment of infectious sustained by resistant microbes.

Loss of microbial diversity and pathogen domination of the gut microbiota in critically ill patients

Among long-stay critically ill patients in the adult intensive care unit (ICU), there are often marked changes in the complexity of the gut microbiota. However, it remains unclear whether such patients might benefit from enhanced surveillance or from interventions targeting the gut microbiota or the pathogens therein. We therefore undertook a prospective observational study of 24 ICU patients, in which serial faecal samples were subjected to shotgun metagenomic sequencing, phylogenetic profiling and microbial genome analyses. Two-thirds of the patients experienced a marked drop in gut microbial diversity (to an inverse Simpson’s index of <4) at some stage during their stay in the ICU, often accompanied by the absence or loss of potentially beneficial bacteria. Intravenous administration of the broad-spectrum antimicrobial agent meropenem was significantly associated with loss of gut microbial diversity, but the administration of other antibiotics, including piperacillin/tazobactam, failed to trigger statistically detectable changes in microbial diversity. In three-quarters of ICU patients, we documented episodes of gut domination by pathogenic strains, with evidence of cryptic nosocomial transmission of Enterococcus faecium. In some patients, we also saw an increase in the relative abundance of apparent commensal organisms in the gut microbiome, including the archaeal species Methanobrevibacter smithii. In conclusion, we have documented a dramatic absence of microbial diversity and pathogen domination of the gut microbiota in a high proportion of critically ill patients using shotgun metagenomics.

Incidence, Risk Factors, and Impact of Clostridium difficile Colitis After Spine Surgery: An Analysis of a National Database

STUDY DESIGN

A retrospective study of prospectively collected data.

OBJECTIVE

The aim of this study was to utilize a large national database with post-hospitalization follow-up data [National Surgical Quality Improvement Program (NSQIP)] to determine the incidence, risk factors, timing, and clinical impact of Clostridium difficile colitis in spine surgery patients.

SUMMARY OF BACKGROUND DATA

Recent literature has suggested an increased incidence of C. difficile infections. However, there has been a lack of large cohort studies defining the incidence and impact of C. difficile colitis in patients undergoing spine surgery.

METHODS

Patients who underwent spine surgical procedures in the 2015 NSQIP database were identified. The primary outcome was a diagnosis of C. difficile colitis within the 30-day postoperative period. Independent risk factors for development of C. difficile colitis were identified using multivariate regression. Postoperative length of stay and rate of 30-day readmission were compared between patients who did and did not develop C. difficile colitis.

RESULTS

A total of 23,981 patients who underwent spine surgical procedures were identified. The incidence of C. difficile colitis was approximately 0.11% [95% confidence interval (95% CI), 0.07-0.16]. Of the cases that developed C. difficile colitis, 70% were diagnosed postdischarge and 88% had not had a pre-existing infection diagnosed. Independent risk factors for the development of C. difficile colitis were combined anterior/posterior lumbar fusion procedures [odds ratio (OR) = 12.29, 95% CI = 2.22-68.13, P = 0.010], greater age (most notably ≥76 years old, OR = 10.31, 95% CI = 3.06-34.76, P < 0.001), hypoalbuminemia (OR = 6.40, 95% CI = 2.49-16.43, P < 0.001), and anemia (OR = 2.39, 95% CI = 1.13-5.05, P = 0.023). The development of C. difficile colitis was associated with greater length of stay (2.2 vs. 12.5 days; P < 0.001) and increased 30-day readmission (OR = 8.21, 95% CI = 3.14-21.45, P < 0.001).

CONCLUSION

C. difficile was diagnosed in 0.11% of patients undergoing spine surgery. The majority of these cases occurred after discharge and in patients not having prior infection diagnoses. High-risk patients should be monitored and targeted with preventative interventions accordingly.

LEVEL OF EVIDENCE

3.

Octahedron Iron Oxide Nanocrystals Prohibited Clostridium difficile Spore Germination and Attenuated Local and Systemic Inflammation

Clinical management of Clostridium difficile infection is still far from satisfactory as bacterial spores are resistant to many chemical agents and physical treatments. Certain types of nanoparticles have been demonstrated to exhibit anti-microbial efficacy even in multi-drug resistance bacteria. However, most of these studies failed to show biocompatibility to the mammalian host cells and no study has revealed in vivo efficacy in C. difficile infection animal models. The spores treated with 500 µg/mL Fe_3-δO₄ nanoparticles for 20 minutes, 64% of the spores were inhibited from transforming into vegetative cells, which was close to the results of the sodium hypochlorite-treated positive control. By cryo-electron micro-tomography, we demonstrated that Fe_3-δO₄ nanoparticles bind on spore surfaces and reduce the dipicolinic acid (DPA) released by the spores. In a C. difficile infection animal model, the inflammatory level triple decreased in mice with colonic C. difficile spores treated with Fe_3-δO₄ nanoparticles. Histopathological analysis showed a decreased intense neutrophil accumulation in the colon tissue of the Fe_3-δO₄ nanoparticle-treated mice. Fe_3-δO₄ nanoparticles, which had no influence on gut microbiota and apparent side effects in vivo, were efficacious inhibitors of C. difficile spore germination by attacking its surface and might become clinically feasible for prophylaxis and therapy.

Safety, Tolerability, Systemic Exposure, and Metabolism of CRS3123, a Methionyl-tRNA Synthetase Inhibitor Developed for Treatment of Clostridium difficile, in a Phase 1 Study

Clostridium difficile causes antibiotic-associated diarrhea and is a major public health concern. Current therapies disrupt the protective intestinal flora, do not reliably prevent recurrent infections, and will be decreasingly effective should less susceptible strains emerge. CRS3123 is an oral agent that inhibits bacterial methionyl-tRNA synthetase and has potent activity against C. difficile and aerobic Gram-positive bacteria but little activity against Gram-negative bacteria, including anaerobes. This first-in-human, double-blind, placebo-controlled, dose escalation study evaluated the safety and systemic exposure of CRS3123 after a single oral dose in healthy adults. Five cohorts of eight subjects each received CRS3123 or placebo in a 3:1 ratio. Doses for the respective active arms were 100 mg, 200 mg, 400 mg, 800 mg, and 1,200 mg. Blood and urine were collected for pharmacokinetic analysis. CRS3123 concentrations were measured with validated LC-MS/MS techniques. There were no serious adverse events or immediate allergic reactions during administration of CRS3123. In the CRS3123-treated groups, the most frequent adverse events were decreased hemoglobin, headache, and abnormal urine analysis; all adverse events in the active-treatment groups were mild to moderate, and their frequency did not increase with dose. Although CRS3123 systemic exposure increased at higher doses, the increase was less than dose proportional. The absorbed drug was glucuronidated at reactive amino groups on the molecule, which precluded accurate pharmacokinetic analysis of the parent drug. Overall, CRS3123 was well tolerated over this wide range of doses. This safety profile supports further investigation of CRS3123 as a treatment for C. difficile infections. (This study has been registered at ClinicalTrials.gov under identifier NCT01551004.).

Gut microbiome and chronic prostatitis/chronic pelvic pain syndrome

Analysis of the human microbiome continues to reveal new and previously unrealized associations between microbial dysbiosis and disease. Novel approaches to bacterial identification using culture-independent methods allow practitioners to discern the presence of alterations in the taxa and diversity of the microbiome and identify correlations with disease processes. While some of these diseases that have been extensively studied are well-defined in their etiology and treatment methods (colorectal cancer), others have provided much more significant challenges in both diagnosis and treatment. One such condition, chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), has several etiological and potentiating contributions from infection, inflammation, central nervous system (CNS) changes, stress, and central sensitization-all factors that play important roles in the crosstalk between the human body and its microbiome. No singular cause of CP/CPPS has been identified and it is most likely a syndrome with multifactorial causes. This heterogeneity and ambiguity are sources of significant frustration for patients and providers alike. Despite multiple attempts, treatment of chronic prostatitis with monotherapy has seen limited success, which is thought to be due to its heterogeneous nature. Phenotypic approaches to both classify the disease and direct treatment for CP/CPPS have proven beneficial in these patients, but questions still remain regarding etiology. Newer microbiome research has found correlations between symptom scores and disease severity and the degree of dysbiosis in urine and gut (stool) microbiomes in these patients as compared to un-afflicted controls. These findings present potential new diagnostic and therapeutic targets in CP/CPPS patients.

Individual-specific changes in the human gut microbiota after challenge with enterotoxigenic Escherichia coli and subsequent ciprofloxacin treatment

Background

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhea in inhabitants from low-income countries and in visitors to these countries. The impact of the human intestinal microbiota on the initiation and progression of ETEC diarrhea is not yet well understood.

Results

We used 16S rRNA (ribosomal RNA) gene sequencing to study changes in the fecal microbiota of 12 volunteers during a human challenge study with ETEC (H10407) and subsequent treatment with ciprofloxacin.

Five subjects developed severe diarrhea and seven experienced few or no symptoms. Diarrheal symptoms were associated with high concentrations of fecal E. coli as measured by quantitative culture, quantitative PCR, and normalized number of 16S rRNA gene sequences. Large changes in other members of the microbiota varied greatly from individual to individual, whether or not diarrhea occurred. Nonetheless the variation within an individual was small compared to variation between individuals. Ciprofloxacin treatment reorganized microbiota populations; however, the original structure was largely restored at one and three month follow-up visits.

Conclusion

Symptomatic ETEC infections, but not asymptomatic infections, were associated with high fecal concentrations of E. coli. Both infection and ciprofloxacin treatment caused variable changes in other bacteria that generally reverted to baseline levels after three months.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2777-0) contains supplementary material, which is available to authorized users.

Antibiotics and the Human Gut Microbiome: Dysbioses and Accumulation of Resistances

The human microbiome is overly exposed to antibiotics, due, not only to their medical use, but also to their utilization in farm animals and crops. Microbiome composition can be rapidly altered by exposure to antibiotics, with potential immediate effects on health, for instance through the selection of resistant opportunistic pathogens that can cause acute disease. Microbiome alterations induced by antibiotics can also indirectly affect health in the long-term. The mutualistic microbes in the human body interact with many physiological processes, and participate in the regulation of immune and metabolic homeostasis. Therefore, antibiotic exposure can alter many basic physiological equilibria, promoting long-term disease. In addition, excessive antibiotic use fosters bacterial resistance, and the overly exposed human microbiome has become a significant reservoir of resistance genes, contributing to the increasing difficulty in controlling bacterial infections. Here, the complex relationships between antibiotics and the human microbiome are reviewed, with focus on the intestinal microbiota, addressing (1) the effects of antibiotic use on the composition and function of the gut microbiota, (2) the impact of antibiotic-induced microbiota alterations on immunity, metabolism, and health, and (3) the role of the gut microbiota as a reservoir of antibiotic resistances.

Impacts of gut bacteria on human health and diseases

Gut bacteria are an important component of the microbiota ecosystem in the human gut, which is colonized by 10¹⁴ microbes, ten times more than the human cells. Gut bacteria play an important role in human health, such as supplying essential nutrients, synthesizing vitamin K, aiding in the digestion of cellulose, and promoting angiogenesis and enteric nerve function. However, they can also be potentially harmful due to the change of their composition when the gut ecosystem undergoes abnormal changes in the light of the use of antibiotics, illness, stress, aging, bad dietary habits, and lifestyle. Dysbiosis of the gut bacteria communities can cause many chronic diseases, such as inflammatory bowel disease, obesity, cancer, and autism. This review summarizes and discusses the roles and potential mechanisms of gut bacteria in human health and diseases.

Clostridium difficile infection: molecular pathogenesis and novel therapeutics

The Gram-positive anaerobic bacterium Clostridium difficile produces toxins A and B, which can cause a spectrum of diseases from pseudomembranous colitis to C. difficile-associated diarrhea. A limited number of C. difficile strains also produce a binary toxin that exhibits ADP ribosyltransferase activity. Here, the structure and the mechanism of action of these toxins as well as their role in disease are reviewed. Nosocomial C. difficile infection is often contracted in hospital when patients treated with antibiotics suffer a disturbance in normal gut microflora. C. difficile spores can persist on dry, inanimate surface for months. Metronidazole and oral vancomycin are clinically used for treatment of C. difficile infection but clinical failure and concern about promotion of resistance are motivating the search for novel non-antibiotic therapeutics. Methods for controlling both toxins and spores, replacing gut microflora by probiotics or fecal transplant, and killing bacteria in the anaerobic gut by photodynamic therapy are discussed.

Clostridium difficile infection is on the rise

The emergence of an epidemic strain makes prevention and early diagnosis critical.

Structure of bacterial transcription factor SpoIIID and evidence for a novel mode of DNA binding

SpoIIID is evolutionarily conserved in endospore-forming bacteria, and it activates or represses many genes during sporulation of Bacillus subtilis. An SpoIIID monomer binds DNA with high affinity and moderate sequence specificity. In addition to a predicted helix-turn-helix motif, SpoIIID has a C-terminal basic region that contributes to DNA binding. The nuclear magnetic resonance (NMR) solution structure of SpoIIID in complex with DNA revealed that SpoIIID does indeed have a helix-turn-helix domain and that it has a novel C-terminal helical extension. Residues in both of these regions interact with DNA, based on the NMR data and on the effects on DNA binding in vitro of SpoIIID with single-alanine substitutions. These data, as well as sequence conservation in SpoIIID binding sites, were used for information-driven docking to model the SpoIIID-DNA complex. The modeling resulted in a single cluster of models in which the recognition helix of the helix-turn-helix domain interacts with the major groove of DNA, as expected. Interestingly, the C-terminal extension, which includes two helices connected by a kink, interacts with the adjacent minor groove of DNA in the models. This predicted novel mode of binding is proposed to explain how a monomer of SpoIIID achieves high-affinity DNA binding. Since SpoIIID is conserved only in endospore-forming bacteria, which include important pathogenic Bacilli and Clostridia, whose ability to sporulate contributes to their environmental persistence, the interaction of the C-terminal extension of SpoIIID with DNA is a potential target for development of sporulation inhibitors.

Effect of low-intensity focused ultrasound on the middle ear in a mouse model of acute otitis media

We hypothesized that low-intensity focused ultrasound (LIFU) increases vessel permeability and antibacterial drug activity in the mouse middle ear. We determined appropriate settings by applying LIFU to mouse ears with the external auditory canal filled with normal saline and performed histologic and immunohistologic examination. Acute otitis media was induced in mice with nontypable Haemophilus influenzae, and they were given ampicillin (50, 10, or 2 mg/kg) intraperitoneally once daily for 3 days with or without LIFU (1.0 W/cm(2), 20% duty cycle, 30 s). In the LIFU(+) groups receiving the 2- and 10-mg/kg doses, viable bacteria counts, number of inflammatory cells and IL-1β and TNF-α levels in middle ear effusion were significantly lower than in the LIFU(-) groups on the same doses. Severity of AOM also tended to be reduced more in the LIFU(+) groups than in the LIFU(-) groups. LIFU application with antibiotics may be effective for middle ear infection.

Epidemiological features of Clostridium difficile infection among inpatients at Hamad General Hospital in the state of Qatar, 2006-2009

The aim of this retrospective study was to evaluate the epidemiology, clinical course and outcome of Clostridium difficile infection among inpatients at Hamad General Hospital in Qatar, from 2006 to 2009. During this period, 123 patients were diagnosed with C. difficile infection and the overall incidence was 1.6/10,000 patient days. The mean age (±SD) of patients was 50.9 ± 21.2 years. The most frequent underlying disease was hypertension 51/123 (41.5%) and 133 prescriptions of antimicrobials were ordered for 105/123 (86.1%) patients prior to C. difficile infection with piperacillin-tazobactam being the most frequently prescribed antimicrobial 39/131 (29.7%). Nosocomial infection was found in 101/123 (82.0%) of cases, and the most common clinical feature was watery diarrhoea 119/123 (96.7%). Antimicrobials were discontinued in 53/105 (50.5%) cases and 118/123 (95.9%) of them received metronidazole as the initial treatment. The mean treatment duration (±SD) was 9.08 ± 5.6 days. Fifteen (12.7%) patients failed the first course of antimicrobial therapy, of which four were treated with oral vancomycin, and eleven patients received both drugs. Recurrence of infection was observed in 12/118 (10.2%) patients and 30-day mortality was 38/123 (30.9%). Several clinical variables were associated with increased 30-day mortality on univariate analysis. Only occurrence of disease among Qataris, prolonged hospitalisation, positive stool occult blood test, high white blood cells and septic shock were found to be independent predictors of mortality by multivariate logistic regression analysis. In conclusion, C. difficile infection was a recognise cause of morbidity and mortality in our hospital with low and stable incidence. It involved predominantly patients younger than 65 years with underlying illness and metronidazole and vancomycin were effective in resolving symptoms in the majority of our patients.

Alternative therapies for Clostridium difficile infections

Clostridium difficile infection is a serious condition responsible for significant morbidity and mortality, especially in patients being treated with antimicrobials. Increasing frequency of the infection and hypervirulent C. difficile strains have resulted in more severe disease as well as therapeutic failures with traditional treatment (metronidazole and vancomycin). To review the studies assessing nontraditional therapies for the prevention and treatment of primary or recurrent C. difficile infection, we conducted a literature search of the PubMed-MEDLINE databases (1984-2010). Of the 98 studies identified, 21 met our inclusion criteria. Five clinical trials and one retrospective medical record review evaluated probiotic or prebiotic formulations for the prevention of C. difficile infection. Only one of these studies, which included Lactobacillus casei and L. bulgaricus in the probiotic formulation, showed efficacy. Ten clinical trials evaluated treatment of an initial episode of C. difficile infection (primary treatment) with the anti-microbials fidaxomicin, fusidic acid, rifampin, teicoplanin, and nitazoxanide, as well as the toxin-binding polymer, tolevamer. Only nitazoxanide and teicoplanin demonstrated noninferiority when compared with vancomycin or metronidazole. Four prospective studies and one retrospective study evaluated treatment of relapsing C. difficile infection. Prebiotic formulations for the prevention and treatment of recurrent C. difficile infection have not proved to be clinically warranted. Nitazoxanide, teicoplanin, and fidaxomicin may be considered as alternatives to traditional treatment; however, clinical experience is limited with these agents for this indication. Bacteriotherapy with fecal instillation has demonstrated high clinical cure rates in case studies and in a retrospective study; however, to our knowledge, randomized clinical trials are lacking for this therapeutic approach. As C. difficile infection rates continue to increase and hypervirulent strains continue to emerge, it is important for future clinical studies to assess alternative therapies.

Clostridium difficile isolates resistant to fluoroquinolones in Italy: emergence of PCR ribotype 018

Recent evidence strongly suggests an association between the use of fluoroquinolones and Clostridium difficile infection (CDI). Resistance to fluoroquinolones has been described not only in the hypervirulent strain 027, but also in other important PCR ribotypes circulating in hospital settings. In a European prospective study conducted in 2005, strains resistant to moxifloxacin represented 37.5% of C. difficile clinical isolates. In this study, we investigated a sample of 147 toxigenic C. difficile isolates, collected in Italy from 1985 to 2008, for the presence of mutations in gyr genes that conferred resistance to fluoroquinolones based on a LightCycler assay. Results were confirmed by the determination of MICs for moxifloxacin. Strains resistant to moxifloxacin were also investigated for resistance to three other fluoroquinolones and for a possible association between fluoroquinolone and macrolide-lincosamide-streptogramin B resistance. C. difficile isolates were typed by PCR ribotyping. In total, 50 clinical isolates showed substitutions in gyr genes and were resistant to fluoroquinolones. Ninety-six percent of the C. difficile resistant isolates showed the substitution Thr82-to-Ile in GyrA, as already observed in the majority of resistant strains worldwide. A significant increase of resistance (P < 0.001) was observed in the period 2002 to 2008 (56% resistant) compared to the period 1985 to 2001 (10% resistant). Coresistance with erythromycin and/or clindamycin was found in 96% (48/50) of the isolates analyzed and, interestingly, 84% of resistant strains were erm(B) negative. The majority of the fluoroquinolone-resistant isolates belonged to PCR ribotype 126 or 018. PCR ribotype 126 was the most frequently found from 2002 to 2005, whereas PCR ribotype 018 was predominant in 2007 and 2008 and still represents the majority of strains typed in our laboratory. Overall, the results demonstrate an increasing number of C. difficile strains resistant to fluoroquinolones in Italy and changes in the prevalence and type of C. difficile isolates resistant to fluoroquinolones circulating over time.

Review of medical and surgical management of Clostridium difficile infection

Clostridium difficile infection (CDI) has become an important area in our daily clinical practice. C. difficile is known to cause a broad spectrum of conditions ranging from asymptomatic carriage, through mild or moderately severe disease with watery diarrhoea, to the life-threatening pseudomembranous colitis (PMC), with toxic megacolon and ileus. Peoples who have been treated with broad-spectrum antibiotics, patients with serious underlying co-morbidities and the elderly are at greatest risk. Over 80% of CDIs reported are in people aged over 65. Due to the alarming increase in its frequency, appearance of more virulent strains and occasional need for life-saving surgical intervention, a more coherent multidisciplinary approach is needed. Combination of rapid turn round time and accurate diagnosis will result in a better management of CDI and a timely implementation of infection control measure. Discontinuation of causative agents such as antibiotic treatment is often curative. In more serious cases, oral administration of metronidazole or vancomycin is the treatment of choice. Relapses of CDI have been reported in about 20-25% of cases, this may increase to 45-60% after the first recurrence. Patients should be treated as soon as possible when the diagnosis of Clostridium difficile colitis is made to avoid sepsis or bowel perforation. Colectomy may improve the outcome of the patient with systemic or complicated Clostridium difficile colitis. This article reviews the changing epidemiological picture, microbiology, histopathology and both medical and surgical managements.

Diagnostic value of repeated enzyme immunoassays in Clostridium difficile infection

OBJECTIVES

There has been a significant increase in the prevalence, severity, and mortality of Clostridium difficile infection (CDI), with an estimated three million new cases per year in the United States. Yet diagnosing CDI remains problematic. The most commonly used test is stool enzyme immunoassay (EIA) detecting toxin A and/or B, but there are no clear guidelines specifying the optimal number of tests to be ordered in the diagnostic workup, although multiple tests are frequently ordered. Thus, we designed a study with the primary objective of evaluating the diagnostic utility of repeat second and third tests of stool EIA detecting both toxins A and B (EIA (A&B)) in cases with negative initial samples, and sought to describe the physicians' patterns of ordering this test in the workup of suspected CDI.

METHODS

A retrospective study was carried out using a database of all stool EIA (A&B) tests ordered for a presumptive diagnosis of CDI. All patients were adults admitted to a major teaching hospital over a three-and-a-half-year period (tests completed within 5 days of ordering the first test were grouped into a single episode, and only the first three samples per episode were analyzed). Age, gender, and results of stool EIA were tabulated. In addition, physicians' ordering patterns and proportion of positive stools relative to the number of tests ordered were also analyzed. A single positive EIA result was interpreted as evidence for the clinical presence of CDI.

RESULTS

A total of 3,712 patients contributed to 5,865 separate diarrhea episodes (total stool EIA (A&B)=9,178), and 1,165 (19.9%) of these episodes were positive for CDI. Of the positive patients, 73.2% were over the age of 65 years and 54.2% of them were females. The most frequent ordering pattern for presumptive CDI was a single stool test (60.1%), followed by two more tests (23.2%). Three tests were still ordered in 16.6% of the cases. Of the 1,165 positive cases, 1,046 (89.8%) were diagnosed in the very first test, 95 (8.2%) in the second, and only 24 (2.0%) in the third test. In 1,934 instances, a second test was ordered after an initial negative result, of which 95 (4.91%) became positive. In 793 episodes, a third test was ordered after two negative samples, of which only 24 (3.03%) became positive.

CONCLUSIONS

This study highlights the low diagnostic yield of repeat stool EIA (A&B) testing. Findings strongly support the utility of limiting the workup of suspected CDI to a single stool test with only one repeat test in cases of high clinical suspicion, and avoiding the routine ordering of multiple stool samples. As Clostridium difficile is becoming an endemic health-care problem resulting in major financial burdens for the US health-care system, clear guidelines specifying the optimal number of stool EIA (A&B) tests to be ordered in the diagnostic workup of suspected CDI must be established to assist physicians in the practice of evidence-based medicine.

Clostridia as agents of zoonotic disease

Clostridia are not normally considered to be zoonotic pathogens, although many species affect both humans and domestic animals. Three cases in which organisms occur, possibly via direct or indirect transmission, in both food animals and humans are considered here. Strains of Clostridium perfringens that produce enterotoxin (CPE) are typically transmitted to humans in contaminated, improperly handled foods. Pathogenesis is based upon action of CPE in the intestine, and disease is usually self-limiting. Infection of domestic animals by CPE-producing C. perfringens is uncommon. C. perfringens type C is best known as a pathogen of neonatal domestic animals, which acquire the infection from the dam. The course may be peracute, and prevention by vaccination of the dam is universally advocated. Humans consuming meat contaminated with type C may develop enteritis necroticans, with segmental hemorrhagic and necrotic jejunitis, which must usually be treated by bowel resection. Clostridium difficile is a pathogen of both humans and domestic animals. Examination of retail meats by bacteriologic culture has revealed genotypes of C. difficile that in many cases are identical to those from food animals and diseased humans. Transmission, food animals to foods to humans, has not been documented.

Inhibitory effect of REP3123 on toxin and spore formation in Clostridium difficile, and in vivo efficacy in a hamster gastrointestinal infection model

OBJECTIVES

REP3123 is a fully synthetic methionyl-tRNA synthetase inhibitor in pre-clinical development as a novel agent to treat Clostridium difficile infection (CDI). This novel agent was investigated for its ability to block the production of toxins and spores, and was tested for efficacy in vivo in a hamster model.

METHODS

Clostridial toxin levels were determined qualitatively using monoclonal antibodies and by cytotoxicity assays. Spores were detected by staining and by quantitative dilution plating after ethanol treatment. Efficacy of REP3123 was tested in a clindamycin-induced C. difficile hamster gastrointestinal (GI) infection model.

RESULTS

REP3123 at concentrations as low as 1 mg/L inhibited de novo toxin production in high cell density, stationary phase cultures of C. difficile. Among comparator agents currently used for CDI therapy, vancomycin required much higher levels of 20 mg/L, and metronidazole had no effect on toxin levels. REP3123 caused a >10-fold reduction of the sporulation rate in vitro. Vancomycin and, in particular, metronidazole appeared to promote the formation of spores. REP3123, at concentrations as low as 0.5 mg/kg, demonstrated efficacy in the hamster model of CDI and was superior to vancomycin in the overall survival of the animals at the end of the study (33 days).

CONCLUSIONS

REP3123 inhibited growth of C. difficile, affected the production of toxins and spores and demonstrated superior efficacy compared with vancomycin in the hamster GI infection model. This agent may be a promising candidate for CDI treatment; in particular, the inhibition of toxin production and spore formation may reduce the severity and spread of the disease, respectively.

The pervasive effects of an antibiotic on the human gut microbiota, as revealed by deep 16S rRNA sequencing

The human intestinal microbiota is essential to the health of the host and plays a role in nutrition, development, metabolism, pathogen resistance, and regulation of immune responses. Antibiotics may disrupt these coevolved interactions, leading to acute or chronic disease in some individuals. Our understanding of antibiotic-associated disturbance of the microbiota has been limited by the poor sensitivity, inadequate resolution, and significant cost of current research methods. The use of pyrosequencing technology to generate large numbers of 16S rDNA sequence tags circumvents these limitations and has been shown to reveal previously unexplored aspects of the “rare biosphere.” We investigated the distal gut bacterial communities of three healthy humans before and after treatment with ciprofloxacin, obtaining more than 7,000 full-length rRNA sequences and over 900,000 pyrosequencing reads from two hypervariable regions of the rRNA gene. A companion paper in PLoS Genetics (see Huse et al., doi: 10.1371/journal.pgen.1000255) shows that the taxonomic information obtained with these methods is concordant. Pyrosequencing of the V6 and V3 variable regions identified 3,300–5,700 taxa that collectively accounted for over 99% of the variable region sequence tags that could be obtained from these samples. Ciprofloxacin treatment influenced the abundance of about a third of the bacterial taxa in the gut, decreasing the taxonomic richness, diversity, and evenness of the community. However, the magnitude of this effect varied among individuals, and some taxa showed interindividual variation in the response to ciprofloxacin. While differences of community composition between individuals were the largest source of variability between samples, we found that two unrelated individuals shared a surprising degree of community similarity. In all three individuals, the taxonomic composition of the community closely resembled its pretreatment state by 4 weeks after the end of treatment, but several taxa failed to recover within 6 months. These pervasive effects of ciprofloxacin on community composition contrast with the reports by participants of normal intestinal function and with prior assumptions of only modest effects of ciprofloxacin on the intestinal microbiota. These observations support the hypothesis of functional redundancy in the human gut microbiota. The rapid return to the pretreatment community composition is indicative of factors promoting community resilience, the nature of which deserves future investigation.

The intestinal microbiota is essential to human health, with effects on nutrition, metabolism, pathogen resistance, and other processes. Antibiotics may disrupt these interactions and cause acute disease, as well as contribute to chronic health problems, although technical challenges have hampered research on this front. Several recent studies have characterized uncultured and complex microbial communities by applying a new, massively parallel technology to obtain hundreds of thousands of sequences of a specific variable region within the small subunit rRNA gene. These shorter sequences provide an indication of diversity. We used this technique to track changes in the intestinal microbiota of three healthy humans before and after treatment with the antibiotic ciprofloxacin, with high sensitivity and resolution, and without sacrificing breadth of coverage. Consistent with previous results, we found that the microbiota of these individuals was similar at the genus level, but interindividual differences were evident at finer scales. Ciprofloxacin reduced the diversity of the intestinal microbiota, with significant effects on about one-third of the bacterial taxa. Despite this pervasive disturbance, the membership of the communities had largely returned to the pretreatment state within 4 weeks.

The most complete survey to date of bacterial diversity in the human gut shows extensive but temporary changes in the microbial community following ciprofloxacin treatment.

What have we learned about antimicrobial use and the risks for Clostridium difficile-associated diarrhoea?

Clostridium difficile is recognized as a major cause of antibiotic-associated diarrhoea and colitis. Antimicrobial agents have been repeatedly recognized as a causative risk for C. difficile-associated diarrhoea (CDAD) and more recently fluoroquinolones have been particularly implicated. Unfortunately, not all reports of antimicrobial associations with CDAD have excluded variables other than antimicrobial use. Prevention of CDAD usually involves infection control interventions and antimicrobial restriction policies may not be fully substantiated by currently available data; however, antimicrobial drug restriction seems prudent in outbreak situations.

Antimicrobial efficacy of copper surfaces against spores and vegetative cells of Clostridium difficile: the germination theory

OBJECTIVES

Persistent contamination of surfaces by spores of Clostridium difficile is a major factor influencing the spread of C. difficile-associated diarrhoea (CDAD) in the clinical setting. In recent years, the antimicrobial efficacy of metal surfaces has been investigated against microorganisms including methicillin-resistant Staphylococcus aureus. This study compared the survival of C. difficile on stainless steel, a metal contact surface widely used in hospitals, and copper surfaces.

METHODS

Antimicrobial efficacy was assessed using a carrier test method against dormant spores, germinating spores and vegetative cells of C. difficile (NCTC 11204 and ribotype 027) over a 3 h period in the presence and absence of organic matter.

RESULTS

Copper metal eliminated all vegetative cells of C. difficile within 30 min, compared with stainless steel which demonstrated no antimicrobial activity (P < 0.05). Copper significantly reduced the viability of spores of C. difficile exposed to the germinant (sodium taurocholate) in aerobic conditions within 60 min (P < 0.05) while achieving a >or=2.5 log reduction (99.8% reduction) at 3 h. Organic material did not reduce the antimicrobial efficacy of the copper surface (P > 0.05).

CONCLUSIONS

The use of copper surfaces within the clinical environment and application of a germination solution in infection control procedures may offer a novel way forward in eliminating C. difficile from contaminated surfaces and reducing CDAD.

Low risk of irritable bowel syndrome after Clostridium difficile infection

OBJECTIVE

The incidence of postinfectious irritable bowel syndrome (IBS) ranges between 4% and 32% of individuals after bacterial or parasitic infection. This study analyzed IBS symptoms in hospitalized patients three months after a symptomatic Clostridium difficile infection.

PATIENTS AND METHODS

All patients with a proven, symptomatic C difficile infection identified in the department of bacteriology over a four-month period were considered for enrolment. Patients were excluded in cases of pre-existing IBS or other organic gastrointestinal diseases. Patients completed both modified Talley and Rome II questionnaires within five days of clinical improvement with metronidazole and at three months postinfection, when stools were cultured and C difficile toxins were examined to exclude ongoing infection.

RESULTS

Twenty-three patients were evaluated three months after infection with C difficile. Just after infection, 15 patients were symptom free, whereas eight patients exhibited symptoms suggestive of IBS. Three months after infection, 22 patients remained symptom free, whereas one patient presented with symptoms indicative of IBS. That female patient had a prolonged infection without vomiting.

CONCLUSIONS

We have shown that while transient functional bowel disorder occurred in 34.7% of patients (eight of 23 patients) recently infected with C difficile, only 4.3% of patients (one of 23 patients) had symptoms indicative of IBS after three months (ie, postinfectious IBS). Because an age-related reduction in immune responsiveness has been documented, it can be speculated that the low incidence of postinfectious IBS may be explained by the older age of the study population. Therefore, it cannot be excluded that the findings may be different in younger patients.

Antibiotic-associated diarrhea: candidate organisms other than Clostridium difficile

BACKGROUND/AIMS

The direct toxic effects of antibiotics on the intestine can alter digestive functions and cause pathogenic bacterial overgrowth leading to antibiotic-associated diarrhea (AAD). Clostridium difficile (C. difficile) is widely known to be responsible for 10 approximately 20% of AAD cases. However, Klebsiella oxytoca, Clostridium perfringens, Staphylococcus aureus, and Candida species might also contribute to AAD.

METHODS

We prospectively analyzed the organisms in stool and colon tissue cultures with a C. difficile toxin A assay in patients with AAD between May and December 2005. In addition, we performed the C. difficile toxin A assays using an enzyme-linked fluorescent assay technique. Patients were enrolled who had diarrhea with more than three stools per day for at least 2 days after the initiation of antibiotic treatment for up to 6 approximately 8 weeks after antibiotic discontinuation.

RESULTS

Among 38 patients (mean age 59 +/- 18 years, M:F =18:20), the organism isolation rates were 28.9% (11/38) for stool culture, 18.4% (7/38) for colon tissue cultures and 13.2% (5/38) for the C. difficile toxin A assay. The overall rate of identification of organisms was 50.0% (19/38). Of the five patients that had a positive result by the C. difficile toxin A assay, two had no organism isolated by the stool or colon tissue culture. The organisms isolated from the stool cultures were C difficile (4), Klebsiella pneumoniae (K. pneumoniae) (3), Candida species (3), and Staphylococcus aureus (1). C. difficile (4) and K. pneumoniae (3) were isolated from the colon tissue culture.

CONCLUSIONS

For C. difficile negative AAD patients, K. pneumoniae, Candida species and Staphylococcus aureus were found to be potential causative organisms.

Early enteral supplementation with key pharmaconutrients improves Sequential Organ Failure Assessment score in critically ill patients with sepsis: outcome of a randomized, controlled, double-blind trial

OBJECTIVE

To assess the safety and efficacy of an early enteral pharmaconutrition supplement containing glutamine dipeptides, antioxidative vitamins and trace elements, and butyrate in critically ill, septic patients.

DESIGN

A prospective, randomized, controlled, double-blind clinical trial.

SETTING

Adult intensive care unit in a university hospital.

PATIENTS

Fifty-five critically ill, septic patients requiring enteral feeding.

INTERVENTIONS

Patients received either an enteral supplement (500 mL of Intestamin, Fresenius Kabi) containing conditionally essential nutrients or a control solution via the nasogastric route for up to 10 days. Inclusion occurred within 24 hrs of intensive care unit admission. Additionally, patients received enteral feeding with an immunonutrition formula (experimental group) or standard formula (control group) initiated within 48 hrs after enrollment.

MEASUREMENTS AND MAIN RESULTS

Organ dysfunction was assessed by daily total Sequential Organ Failure Assessment (SOFA) score over the 10-day study period in both patient groups. Patients receiving the experimental supplement showed a significantly faster decline in the regression slopes of delta daily total SOFA score over time compared with control. The difference between the regression coefficients of the two slopes was significant irrespective of the level of analysis: intent to treat -0.32 vs. -0.14, p < .0001; per protocol -0.34 vs. -0.14, p < .0001; and completers (patients receiving > or = 80% of the calculated caloric target over a period of 6 days), -0.26 vs. -0.16, p = .0005. Vitamin C, as a marker of supplement absorption, increased from 10.6 (1.9-159.4) micromol/L (normal range 20-50 micromol/L) on day 1 to 58.7 (5.4-189.9) micromol/L by day 3 (p = .002) in the intervention group but remained below the normal range in the control group 17.0 (2.8-78.5) on day 1 and 14.3 (2.4-179.6) on day 3. Serum levels of glycine, serine, arginine, ornithine, vitamin E, and beta-carotene all increased significantly with treatment in the supplementation group.

CONCLUSIONS

In medical patients with sepsis, early enteral pharmaconutrition with glutamine dipeptides, vitamin C and E, beta-carotene, selenium, zinc, and butyrate in combination with an immunonutrition formula results in significantly faster recovery of organ function compared with control.

Pharmacodynamic studies of vancomycin, metronidazole and fusidic acid against Clostridium difficile

BACKGROUND

Pharmacodynamic studies of antibiotics have attracted great interest in recent years. However, studies on the pharmacodynamics of different antibiotics against Clostridium difficile are scarce.

METHODS

The postantibiotic effects (PAE) and the postantibiotic sub-minimum inhibitory concentration (MIC) effects (PA SME) of vancomycin, metronidazole and fusidic acid were investigated by viable counts against three different strains of C. difficile. The killing rate and extent of the three antibiotics against the same strains were also studied by adding 2, 4, 8, 16 and 32x MIC of the three antibiotics, respectively.

RESULTS

Metronidazole exerted a very rapid bactericidal effect at concentrations of 8x MIC and above against all three strains investigated. Vancomycin gave overall less kill in comparison to metronidazole and was bacteriostatic against two of the three strains. Fusidic acid exerted a concentration-dependent killing against two of the strains. Vancomycin exerted short PAEs and PA SMEs against all three strains. Significantly longer PAEs and PA SMEs were noted for fusidic acid. Metronidazole gave similar short PAEs like vancomycin but longer PA SMEs were noted against two of the investigated strains.

CONCLUSION

Metronidazole exerted the most prominent bactericidal effect greater than fusidic acid and greater than vancomycin. Fusidic acid gave overall the longest PAEs and PA SMEs greater than metronidazole and greater than vancomycin.

Detection of a Genetic Linkage Between Genes Coding for Resistance to Tetracycline and Erythromycin inClostridium difficile

Elements carrying more than one antibiotic resistance gene have never been found in Clostridium difficile, one of the major causes of nosocomial diarrheic diseases. In this study, C. difficile isolates were investigated for a possible genetic linkage between tet(M) and erm(B), the most frequent genes found in strains resistant to tetracycline and erythromycin. In the majority of C. difficile strains, tet(M) is carried by Tn5397. However, tet(M) genes carried by Tn916-like elements have been found in recent clinical isolates. As far as erythromycin resistance is concerned, the only completely characterized transposon harboring an erm(B) gene in C. difficile is Tn5398, even if ErmB determinants probably carried by other elements have been identified. Among the 100 C. difficile isolates screened in this study, 27 were positive for tet(M) and erm(B). Twenty five of these strains were positive for tndX, used as marker for Tn5397, whereas two were positive for int, used as marker for Tn916-like elements. The latter isolates showed two tet(M) genes: one was carried by a Tn916-like element, able to transfer to a recipient C. difficile strain, whereas the second was genetically linked to an erm(B) in a composite element probably unable to conjugate. Molecular analysis of C. difficile cd1911 tet(M)-erm(B) DNA sequence demonstrated that this region has arisen by recombination of DNA fragments from different plasmids and transposons. This is the first demonstration that C. difficile is able to accumulate and maintain antibiotic resistance genes, as observed in other pathogens.

Risk factors for Clostridium difficile toxin-positive nosocomial diarrhoea

Data were retrieved from the records of all patients from whom stool was sent for Clostridium difficile toxin testing during the year 2001. Toxin-positive and -negative patients were compared by bivariate analysis and regression models. Eight hundred samples from 610 patients were sent for C. difficile toxin testing. Charts of 535 patients (88%) were available for analysis. Of those, 17% had a positive toxin test whilst 83% had a negative toxin test. There was no difference in the number of daily bowel movements between the two groups. Toxin-positive patients were older (P<0.0001), more often came from nursing homes (P<0.05), had higher leukocyte counts (P<0.001), higher blood urea nitrogen (P<0.01), lower serum albumin (P<0.01) and more often received diuretics (P<0.01) and clindamycin (P<0.05). Logistic regression analysis showed that previous antibiotic-associated diarrhoea was the most significant risk factor for toxin-positive diarrhoea (P<0.001), followed by clindamycin treatment (P<0.005), diuretics (P<0.005) and older age (P<0.05). Another logistic model showed the contribution of macrolides (P<0.05) to the development of hospital-acquired diarrhoea.