Detection, treatment, and prevention of Clostridium difficile infection

Five-Day Treatment with B. licheniformis Along with Classical Vancomycin Treatment Was Effective in Preserving Gut Microbiota in Patients with Clostridioides difficile Infection

Background/Objectives:Clostridioides difficile infection (CDI) is an important nosocomial diarrheal disease. The benefits of the probiotic Bacillus licheniformis (B. licheniformis) in the preservation of intestinal microbiota have not been studied in patients with CDI to date. Therefore, we aimed to investigate the efficacy of B. licheniformis in preserving the intestinal microbiota in patients with CDI. Methods: A multicenter, randomized, placebo-controlled trial was carried out at six academic centers in Korea. Individuals diagnosed with mild to moderate CDI were included in this trial. CDI was treated with vancomycin 125 mg four times daily for two weeks. Along with vancomycin, B. licheniformis was administered for five days in this study, while a placebo was given to the placebo group. Microbiome analysis was performed before and five days after administering vancomycin and B. licheniformis or placebo, using 16S rRNA amplicon sequencing. Alpha and beta diversity was compared between the two groups. Results: A total of 35 participants were finally included in this study, with 16 in the study group and 19 in the placebo group. The alpha diversity was similar in both groups before CDI treatment. After five days of the administration of vancomycin and B. licheniformis or placebo, alpha diversity did not decrease in the study group (Chao1 index, p = 0.665; observed features, p = 0.692). In contrast, alpha diversity decreased in the placebo group (Chao1 index, p = 0.011; observed features, p = 0.011). Beta diversity did not differ between the two groups. Conclusions: The addition of B. licheniformis to vancomycin was effective in preserving gut microbiota in patients with CDI.

Polysaccharide lyase PL3.3 possibly potentiating Clostridioides difficile clinical symptoms based on complete genome analysis of RT046/ST35 and RT012/ST54

Clostridioides difficile has rapidly become a major cause of nosocomial infectious diarrhea worldwide due to the misuse of antibiotics. Our previous study confirmed that RT046/ST35 strain is associated with more severe clinical symptoms compared to RT012/ST54 strain. We conducted genome comparison of the RT046/ST35 and RT012/ST54 strains using whole-genome sequencing technology. The RT046/ST35 strain had a genome length of 7,869,254 bp with a GC content of 29.49%. The original length of the RT012/ST54 strain was 7,499,568 bp with a GC content of 29.64%. Additionally, we detected plasmid1 in the RT046/ST54 strain. We found that the RT046/ST35 strain had more genomic islands compared to the RT012/ST54 strain, and we identified polysaccharide lyase (PL) in the region around 2.2 M. Furthermore, we discovered that the increased severity of clinical symptoms in the RT046/ST35 strain compared to the RT012/ST54 strain was unrelated to virulence factors and emphasized the potential crucial role of PL in RT046/ST35. There were almost no differences in eggNOG annotation and KEGG annotation between RT046/ST35 and RT012/ST54. RT046/ST35 had more mRNA processes in GO annotation. In conclusion, our study suggests that the core factor contributing to the more serious clinical symptoms of the RT046/ST35 strain compared to the RT012/ST54 strain is possibly PL.

Not only COVID-19: a systematic review of anti-COVID-19 measures and their effect on healthcare-associated infections

BACKGROUND

Healthcare-associated infections (HAIs) burden healthcare globally. Amid the SARS-CoV-2 pandemic, intensified infection control measures, such as mask usage and hand hygiene, were implemented.

AIM

To assess the efficacy of these measures in preventing HAIs among hospitalized patients.

METHODS

Using the PICO framework (Population, Intervention, Comparison, Outcome), the study focused on hospitalized patients and the effectiveness of anti-COVID-19 measures in preventing HAIs. A systematic review of literature published in 2020-2022 was conducted, examining interventions such as mask usage, hand hygiene, and environmental cleaning.

FINDINGS

This systematic review analysed 42 studies: two in 2020, 21 in 2021, and 19 in 2022. Most studies were from high-income countries (28). Most studies (30 out of 42) reported a reduction in HAIs after implementing anti-COVID-19 measures. Gastrointestinal infections and respiratory tract infections showed significant reduction, unlike bloodstream infections and urinary tract infections. Some wards, like cardiology and neurology, experienced reduced HAIs, unlike intensive care units and coronary care units. There was an increase in studies reporting no effect of hygiene measures on HAIs in 2022, eventually indicating a shift in effectiveness over time.

CONCLUSION

Anti-COVID-19 measures have shown selective efficacy in preventing HAIs. The study emphasizes the need for context-specific strategies and increased focus on regions with limited resources. Continued research is essential to refine infection control practices, especially in high-risk settings.

An Overview of Equine Enteric Clostridial Diseases

The understanding of the pathogenesis of equine enteric clostridial organisms is an active, evolving field. Advances will improve our knowledge both from the animal welfare and human health perspectives. The zoonotic nature of this group of diseases makes them relevant in the age of One health, as a significant amount of close human-equine interactions occurs for business and pleasure. Economic and welfare reasons prompt a better understanding of enteric clostridial pathogenesis, treatment, and control of the infection in horses and ongoing efforts are needed to advance clinical outcomes.

Detection and pathogenic potential of Clostridium difficile in commercial meat and meat products in Brazil

The aims of this study were to evaluate the occurrence of Clostridium difficile in commercial raw meat and meat products commercialized in Brazil, and to determine the pathogenic potential and antimicrobial susceptibility of the isolates. After selective enrichment, the isolation of C. difficile involved plating with and without an alcohol shock treatment onto C. difficile moxalactam agar (CDMNA). The toxigenic profile was determined through PCR for detection of tcdA, tcdB, cdtA and cdtB genes and an enzyme-linked immunosorbent assay for toxin A/B. C. difficile was isolated from 8.9% (17 out of 192) of analyzed samples. Plating without alcohol treatment (sensitivity of 88.23%) was more efficient than with alcohol treatment (sensitivity of 29.41%) in C. difficile isolation. The profile A + B+CDT- was observed in 35.0% (28/80) of the isolates. The A/B toxin was tested in 44 isolates and 15.9% of them were positive. Resistance to clindamycin, ceftizoxime tetracycline, metronidazole, vancomycin, and ceftriaxone were observed among isolates. Multi-drug resistance was detected in 36.4% (8/22) of the isolates evaluated.

Lipid Species in the GI Tract are Increased by the Commensal Fungus Candida albicans and Decrease the Virulence of Clostridioides difficile

Prior antibiotic treatment is a risk factor for Clostridioides difficile infection (CDI); the commensal gut microbiota plays a key role in determining host susceptibility to the disease. Previous studies demonstrate that the pre-colonization of mice with a commensal fungus, Candida albicans, protects against a lethal challenge with C. difficile spores. The results reported here demonstrate that the cecum contents of antibiotic-treated mice with C. albicans colonization contained different levels of several lipid species, including non-esterified, unsaturated long-chain fatty acids compared to non-C. albicans-colonized mice. Mice fed olive oil for one week and challenged with C. difficile spores showed enhanced survival compared to PBS-fed mice. The amount of olive oil administered was not sufficient to cause weight gain or to result in significant changes to the bacterial microbiota, in contrast to the effects of a high-fat diet. Furthermore, the direct exposure of C. difficile bacteria in laboratory culture to the unsaturated fatty acid oleic acid, the major fatty acid found in olive oil, reduced the transcription of genes encoding the toxins and reduced the survival of bacteria in the post-exponential phase. Therefore, the effects of C. albicans on the metabolite milieu contributed to the attenuation of C. difficile virulence.

In Vitro Selection of a DNA Aptamer Targeting Degraded Protein Fragments for Biosensing

Protein biomarkers often exist as degradation fragments in biological samples, and affinity agents derived using a purified protein may not recognize them, limiting their value for clinical diagnosis. Herein, we present a method to overcome this issue, by selecting aptamers against a degraded form of the toxin B protein, which is a marker for diagnosing toxigenic Clostridium difficile infections. This approach has led to isolation of a DNA aptamer that recognizes degraded toxin B, fresh toxin B, and toxin B spiked into human stool samples. DNA aptamers selected using intact recombinant toxin B failed to recognize degraded toxin B, which is the form present in stored stool samples. Using this new aptamer, we produced a simple paper-based analytical device for colorimetric detection of toxin B in stool samples, or in the NAP1 strain of Clostridium difficile. The combined aptamer-selection and paper-sensing strategy can expand the practical utility of DNA aptamers in clinical diagnosis.

Clostridium difficile-associated disease and Helicobacter pylori seroprevalence: A case-control study

BACKGROUND

Helicobacter pylori inhabits the stomach and causes persistent inflammation, with changes in gastric acidity. However, it is unclear whether the presence of H pylori plays a role in Clostridium difficile-associated disease (CDAD). The study's aim was to examine relationships of H pylori seroprevalence and serum pepsinogens (PGs), as markers of gastric inflammation, with CDAD.

MATERIALS AND METHODS

A case-control study was conducted among 49 CDAD cases and 54 controls (median age 82 years). Using enzyme-linked immunosorbent assays, sera were tested for H pylori IgG antibody, and PGI and PGII levels. Helicobacter pylori-positive samples were tested for IgG antibody to recombinant cytotoxin-associated gene A (CagA) virulent protein. Logistic regression models were fitted.

RESULTS

Cases and controls were comparable in age (P = .5) and sex distribution (females 62% vs 57%, P = .6). Helicobacter pylori IgG seroprevalence was 47%, of whom 23% were CagA seropositives. Among cases compared to controls, 43% vs 28% were H pylori seropositive but lacking CagA IgG antibody: adjusted odd ratio (OR) 3.43 (95% confidence intervals [CI] 1.29-9.10); 18% vs 4% were positive for CagA phenotype: adjusted OR 9.32 (95% CI 1.61-53.76). This association was not affected by PG levels.

CONCLUSIONS

Helicobacter pylori infection, especially with CagA virulent phenotype, might predispose to C difficile infection in elderly patients.

Risk Factors and Outcomes Associated With Treatment of Asymptomatic Bacteriuria in Hospitalized Patients

IMPORTANCE

Treatment of asymptomatic bacteriuria (ASB) with antibiotics is a common factor in inappropriate antibiotic use, but risk factors and outcomes associated with treatment of ASB in hospitalized patients are not well defined.

OBJECTIVE

To evaluate factors associated with treatment of ASB among hospitalized patients and the possible association between treatment and clinical outcomes.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study was conducted from January 1, 2016, through February 1, 2018, at 46 hospitals participating in the Michigan Hospital Medicine Safety Consortium. A total of 2733 hospitalized medical patients with ASB, defined as a positive urine culture without any documented signs or symptoms attributable to urinary tract infection, were included in the analysis.

EXPOSURES

One or more antibiotic dose for treatment of ASB.

MAIN OUTCOMES AND MEASURES

Estimators of antibiotic treatment of ASB. Secondary outcomes included 30-day mortality, 30-day hospital readmission, 30-day emergency department visit, discharge to post-acute care settings, Clostridioides difficile infection (formerly known as Clostridium difficile) at 30 days, and duration of hospitalization after urine testing.

RESULTS

Of 2733 patients with ASB, 2138 were women (78.2%); median age was 77 years (interquartile range [IQR], 66-86 years). A total of 2259 patients (82.7%) were treated with antibiotics for a median of 7 days (IQR, 4-9 days). Factors associated with ASB treatment included older age (odds ratio [OR], 1.10 per 10-year increase; 95% CI, 1.02-1.18), dementia (OR, 1.57; 95% CI, 1.15-2.13), acutely altered mental status (OR, 1.93; 95% CI, 1.23-3.04), urinary incontinence (OR, 1.81; 95% CI, 1.36-2.41), leukocytosis (white blood cell count >10 000/μL) (OR, 1.55; 95% CI, 1.21-2.00), positive urinalysis (presence of leukocyte esterase or nitrite, or >5 white blood cells per high-power field) (OR, 2.83; 95% CI, 2.05-3.93), and urine culture with a bacterial colony count greater than 100 000 colony-forming units per high-power field (OR, 2.30; 95% CI, 1.83-2.91). Treatment of ASB was associated with longer duration of hospitalization after urine testing (4 vs 3 days; relative risk, 1.37; 95% CI, 1.28-1.47). No other differences in secondary outcomes were identified after propensity weighting.

CONCLUSIONS AND RELEVANCE

Hospitalized patients with ASB commonly receive inappropriate antibiotic therapy. Antibiotic treatment did not appear to be associated with improved outcomes; rather, treatment may be associated with longer duration of hospitalization after urine testing. To possibly reduce inappropriate antibiotic use, stewardship efforts should focus on improving urine testing practices and management strategies for elderly patients with altered mental status.

Excess Antibiotic Treatment Duration and Adverse Events in Patients Hospitalized With Pneumonia: A Multihospital Cohort Study

BACKGROUND

Randomized trials demonstrate no benefit from antibiotic treatment exceeding the shortest effective duration.

OBJECTIVE

To examine predictors and outcomes associated with excess duration of antibiotic treatment.

DESIGN

Retrospective cohort study.

SETTING

43 hospitals in the Michigan Hospital Medicine Safety Consortium.

PATIENTS

6481 general care medical patients with pneumonia.

MEASUREMENTS

The primary outcome was the rate of excess antibiotic treatment duration (excess days per 30-day period). Excess days were calculated by subtracting each patient's shortest effective (expected) treatment duration (based on time to clinical stability, pathogen, and pneumonia classification [community-acquired vs. health care-associated]) from the actual duration. Negative binomial generalized estimating equations (GEEs) were used to calculate rate ratios to assess predictors of 30-day rates of excess duration. Patient outcomes, assessed at 30 days via the medical record and telephone calls, were evaluated using logit GEEs that adjusted for patient characteristics and probability of treatment.

RESULTS

Two thirds (67.8% [4391 of 6481]) of patients received excess antibiotic therapy. Antibiotics prescribed at discharge accounted for 93.2% of excess duration. Patients who had respiratory cultures or nonculture diagnostic testing, had a longer stay, received a high-risk antibiotic in the prior 90 days, had community-acquired pneumonia, or did not have a total antibiotic treatment duration documented at discharge were more likely to receive excess treatment. Excess treatment was not associated with lower rates of any adverse outcomes, including death, readmission, emergency department visit, or Clostridioides difficile infection. Each excess day of treatment was associated with a 5% increase in the odds of antibiotic-associated adverse events reported by patients after discharge.

LIMITATION

Retrospective design; not all patients could be contacted to report 30-day outcomes.

CONCLUSION

Patients hospitalized with pneumonia often receive excess antibiotic therapy. Excess antibiotic treatment was associated with patient-reported adverse events. Future interventions should focus on whether reducing excess treatment and improving documentation at discharge improves outcomes.

PRIMARY FUNDING SOURCE

Blue Cross Blue Shield of Michigan (BCBSM) and Blue Care Network as part of the BCBSM Value Partnerships program.

In Vitro Selection of Circular DNA Aptamers for Biosensing Applications

We report on the first effort to select DNA aptamers from a circular DNA library, which resulted in the discovery of two high-affinity circular DNA aptamers that recognize the glutamate dehydrogenase (GDH) from Clostridium difficile, an established antigen for diagnosing Clostridium difficile infection (CDI). One aptamer binds effectively in both the circular and linear forms, the other is functional only in the circular configuration. Interestingly, these two aptamers recognize different epitopes on GDH, demonstrating the advantage of selecting aptamers from circular DNA libraries. A sensitive diagnostic test was developed to take advantage of the high stability of circular DNA aptamers in biological samples and their compatibility with rolling circle amplification. This test is capable of identifying patients with active CDI using stool samples. This work represents a significant step forward towards demonstrating the practical utility of DNA aptamers in clinical diagnosis.

All disease begins in the gut: Influence of gastrointestinal disorders and surgery on oral drug performance

The term "disease" conjures a plethora of graphic imagery for many, and the use of drugs to combat symptoms and treat underlying pathology is at the core of modern medicine. However, the effects of the various gastrointestinal diseases, infections, co-morbidities and the impact of gastrointestinal surgery on the pharmacokinetic and pharmacodynamic behaviour of drugs have been largely overlooked. The better elucidation of disease pathology and the role of underlying cellular and molecular mechanisms have increased our knowledge as far as diagnoses and prognoses are concerned. In addition, the recent advances in our understanding of the intestinal microbiome have linked the composition and function of gut microbiota to disease predisposition and development. This knowledge, however, applies less so in the context of drug absorption and distribution for orally administered dosage forms. Here, we revisit and re-evaluate the influence of a portfolio of gastrointestinal diseases and surgical effects on the functionality of the gastrointestinal tract, their implications for drug delivery and attempt to uncover significant links for clinical practice.

Actoxumab + bezlotoxumab combination: what promise for Clostridium difficile treatment?

INTRODUCTION

Clostridium difficile infection (CDI) is the most common healthcare-associated infection worldwide. As standard CDI antibiotic therapies can result in unacceptably high recurrence rates, novel therapeutic strategies for CDI are necessary. A recently emerged immunological therapy is a monoclonal antibody against C. difficile toxin B. Areas covered: In this review, the authors summarize the available pharmacological, preclinical, and clinical data for the CDI treatment based on anti-toxin A (actoxumab) and anti-toxin B (bezlotoxumab) human monoclonal antibodies (HuMabs), and discuss about the potentiality of a therapy that includes HuMab combined administration for CDI. Expert opinion: Although only bezlotoxumab is indicated to reduce recurrence of CDI, experimental studies using a combination of HuMabs actoxumab and bezlotoxumab have shown that bolstering the host immune response against both the C. difficile toxins may be effective in primary and secondary CDI prevention. Besides neutralizing both the key virulence factors, combination of two HuMabs could potentially offer an advantage for a yet to emerge C. difficile strain, which is a steady threat for patients at high risk of CDI. However, as actoxumab development was halted, passive immunotherapy with actoxumab/bezlotoxumab is actually impracticable. Future research will be needed to assess HuMab combination as a therapeutic strategy in clinical and microbiological cure of CDI.

Updated meta-analysis of controlled observational studies: proton-pump inhibitors and risk of Clostridium difficile infection

Attention has recently been directed toward a plausible link between Clostridium difficile infection (CDI) and proton-pump inhibitors (PPIs). However, the results of studies on the association between CDI and PPI remain controversial. We searched the literature databases from their inception to December 2016, without restriction of language, including all controlled observational studies examining the association between acid-suppressive therapy and CDI. Pooled analysis of 50 studies showed a significant association between PPI use and risk of developing CDI (odds ratio: 1.26; 95% confidence interval: 1.12-1.39) as compared with non-users. When stratified by study patients, the relative risk of hospital-acquired CDI and community-associated CDI were 1.29 (1.14-1.44) and 1.17 (0.74-1.59). After restricting the studies according to hospital department, the relative risks of hospital-acquired CDI in ICUs and general wards were 1.43 (0.74-2.11) and 1.29 (1.13-1.45). By implementing cumulative meta-analysis, it was clear that earlier trials of CDI conducted in the early 2000s demonstrated a high degree of heterogeneity and a high percentage of negative results. Since 2011, the overall association between PPI use and risk of developing CDI has remained relatively stable within an effect size between OR 1.20 and 1.26. Our findings indicate a significant associated risk of incident CDI among PPI users, especially in general ward patients. The totality of evidence, when using cumulative meta-analysis, showed that further trials are unlikely to overturn this positive result. Therefore establishing a guideline for the use of PPIs may help in future with the control of CDI.

A Nutrient-Regulated Cyclic Diguanylate Phosphodiesterase Controls Clostridium difficile Biofilm and Toxin Production during Stationary Phase

The signaling molecule cyclic diguanylate (c-di-GMP) mediates physiological adaptation to extracellular stimuli in a wide range of bacteria. The complex metabolic pathways governing c-di-GMP synthesis and degradation are highly regulated, but the specific cues that impact c-di-GMP signaling are largely unknown. In the intestinal pathogen Clostridium difficile, c-di-GMP inhibits flagellar motility and toxin production and promotes pilus-dependent biofilm formation, but no specific biological functions have been ascribed to any of the individual c-di-GMP synthases or phosphodiesterases (PDEs). Here, we report the functional and biochemical characterization of a c-di-GMP PDE, PdcA, 1 of 37 confirmed or putative c-di-GMP metabolism proteins in C. difficile 630. Our studies reveal that pdcA transcription is controlled by the nutrient-regulated transcriptional regulator CodY and accordingly increases during stationary phase. In addition, PdcA PDE activity is allosterically regulated by GTP, further linking c-di-GMP levels to nutrient availability. Mutation of pdcA increased biofilm formation and reduced toxin biosynthesis without affecting swimming motility or global intracellular c-di-GMP. Analysis of the transcriptional response to pdcA mutation indicates that PdcA-dependent phenotypes manifest during stationary phase, consistent with regulation by CodY. These results demonstrate that inactivation of this single PDE gene is sufficient to impact multiple c-di-GMP-dependent phenotypes, including the production of major virulence factors, and suggest a link between c-di-GMP signaling and nutrient availability.

Risk of Clostridium difficile Infection with the Use of a Proton Pump Inhibitor for Stress Ulcer Prophylaxis in Critically Ill Patients

Background/Aims

Proton pump inhibitors (PPIs) and histamine-2 receptor antagonists (H2RAs) are commonly prescribed for stress ulcer prophylaxis (SUP) in critically ill patients. Several studies have suggested that the use of PPIs is a potential risk factor for Clostridium difficile infection (CDI). We compared the incidences of CDI in the PPI group and H2RA group for SUP in critically ill patients.

Methods

From August 2005 to July 2012, the incidences of CDI were retrospectively analyzed in patients who were admitted directly to intensive care units and stayed for more than 3 days. SUP-related CDI was defined as a CDI diagnosed during the SUP period. Patient clinical data were analyzed to identify potential risk factors for SUP-related CDI.

Results

Of the 1,005 patients enrolled (444 patients received PPI and 561 received H2RA), 38 (3.8%) were diagnosed with SUP-related CDI. The incidence of SUP-related CDI was considerably higher in patients who received PPI than in those who received H2RA (6.7% vs 1.8%). PPI use for SUP (odds ratio [OR], 3.3; confidence interval [CI], 1.5 to 7.1; p=0.003) and diabetes mellitus (OR, 2.3; CI, 1.2 to 4.7; p=0.019) were independent risk factors for SUP-related CDI.

Conclusions

PPI therapy is associated with a higher risk of SUP-related CDI than H2RA therapy in critically ill patients.

Proteome mining for the identification and in-silico characterization of putative drug targets of multi-drug resistant Clostridium difficile strain 630

Clostridium difficile is an enteric pathogen that causes approximately 20% to 30% of antibiotic-associated diarrhea. In recent years, there has been a substantial rise in the rate of C. difficile infections as well as the emergence of virulent and antibiotic resistant C. difficile strains. So, there is an urgent need for the identification of therapeutic potential targets and development of new drugs for the treatment and prevention of C. difficile infections. In the current study, we used a hybrid approach by combining sequence similarity-based approach and protein-protein interaction network topology-based approach to identify and characterize the potential drug targets of C. difficile. A total of 155 putative drug targets of C. difficile were identified and the metabolic pathway analysis of these putative drug targets using DAVID revealed that 46 of them are involved in 9 metabolic pathways. In-silico characterization of these proteins identified seven proteins involved in pathogen-specific peptidoglycan biosynthesis pathway. Three promising targets viz. homoserine dehydrogenase, aspartate-semialdehyde dehydrogenase and aspartokinase etc. were found to be involved in multiple enzymatic pathways of the pathogen. These 3 drug targets are of particular interest as they can be used for developing effective drugs against multi-drug resistant C. difficile strain 630 in the near future.

Cyclic diguanylate signaling in Gram-positive bacteria

The nucleotide second messenger 3'-5' cyclic diguanylate monophosphate (c-di-GMP) is a central regulator of the transition between motile and non-motile lifestyles in bacteria, favoring sessility. Most research investigating the functions of c-di-GMP has focused on Gram-negative species, especially pathogens. Recent work in Gram-positive species has revealed that c-di-GMP plays similar roles in Gram-positives, though the precise targets and mechanisms of regulation may differ. The majority of bacterial life exists in a surface-associated state, with motility allowing bacteria to disseminate and colonize new environments. c-di-GMP signaling regulates flagellum biosynthesis and production of adherence factors and appears to be a primary mechanism by which bacteria sense and respond to surfaces. Ultimately, c-di-GMP influences the ability of a bacterium to alter its transcriptional program, physiology and behavior upon surface contact. This review discusses how bacteria are able to sense a surface via flagella and type IV pili, and the role of c-di-GMP in regulating the response to surfaces, with emphasis on studies of Gram-positive bacteria.

Pathway to Prevention of Nosocomial Clostridium difficile Infection

BACKGROUND

To address the significant morbidity and mortality rates associated with nosocomial Clostridium difficile-associated diarrhea (CDAD), a series of recommendations and a pathway to prevention were developed.

METHODS

An expert panel of infectious disease (ID) specialists participated in a modified Delphi process with specific objectives: (1) conduct a review for CDAD and prevention; (2) develop statements based upon panel members' opinions; (3) hold a panel meeting during the 2012 IDWeek; and (4) review the final recommendations and prevention pathway prior to submission for publication.

RESULTS

The panel voted on (1) antibiotic stewardship (7 of 8 panelists); (2) reduction of other potentially modifiable risk factors (variable); (3) utilization of specific probiotics to prevent C. difficile overgrowth (8/8); (4) staff education regarding CDAD preventive measures (8/8); (5) appropriate hand hygiene for everyone (7/8); (6) environmental cleaning (8/8); (7) medical equipment disinfection (7/8); (8) early detection of CDAD in symptomatic patients (7/8); (9) usage of protective clothing/gloves (8/8); (10) proper measures during outbreak (8/8); and (11) surveillance to monitor efficacy data of preventive measures (8/8).

CONCLUSIONS

The panel members agreed with 11 of 17 recommendations presented. The additional recommendations by the panel were proton pump inhibitor use as a risk factor and the use of adjunctive therapy with specific probiotic, as it was approved by Health Canada for the risk reduction of CDAD in hospitalized patients.

Regulation of Type IV Pili Contributes to Surface Behaviors of Historical and Epidemic Strains of Clostridium difficile

The intestinal pathogen Clostridium difficile is an urgent public health threat that causes antibiotic-associated diarrhea and is a leading cause of fatal nosocomial infections in the United States. C. difficile rates of recurrence and mortality have increased in recent years due to the emergence of so-called "hypervirulent" epidemic strains. A great deal of the basic biology of C. difficile has not been characterized. Recent findings that flagellar motility, toxin synthesis, and type IV pilus (TFP) formation are regulated by cyclic diguanylate (c-di-GMP) reveal the importance of this second messenger for C. difficile gene regulation. However, the function(s) of TFP in C. difficile remains largely unknown. Here, we examine TFP-dependent phenotypes and the role of c-di-GMP in controlling TFP production in the historical 630 and epidemic R20291 strains of C. difficile. We demonstrate that TFP contribute to C. difficile biofilm formation in both strains, but with a more prominent role in R20291. Moreover, we report that R20291 is capable of TFP-dependent surface motility, which has not previously been described in C. difficile. The expression and regulation of the pilA1 pilin gene differs between R20291 and 630, which may underlie the observed differences in TFP-mediated phenotypes. The differences in pilA1 expression are attributable to greater promoter-driven transcription in R20291. In addition, R20291, but not 630, upregulates c-di-GMP levels during surface-associated growth, suggesting that the bacterium senses its substratum. The differential regulation of surface behaviors in historical and epidemic C. difficile strains may contribute to the different infection outcomes presented by these strains.

IMPORTANCE

How Clostridium difficile establishes and maintains colonization of the host bowel is poorly understood. Surface behaviors of C. difficile are likely relevant during infection, representing possible interactions between the bacterium and the intestinal environment. Pili mediate bacterial interactions with various surfaces and contribute to the virulence of many pathogens. We report that type IV pili (TFP) contribute to biofilm formation by C. difficile. TFP are also required for surface motility, which has not previously been demonstrated for C. difficile. Furthermore, an epidemic-associated C. difficile strain showed higher pilin gene expression and greater dependence on TFP for biofilm production and surface motility. Differences in TFP regulation and their effects on surface behaviors may contribute to increased virulence in recent epidemic strains.

Media Discourse on the Social Acceptability of Fecal Transplants

Advances in human microbiome research have generated considerable interest in elucidating the role of bacteria in health and the application of microbial ecosystem therapies and probiotics. Fecal transplants involve the introduction of gut microbes from a healthy donor's stool to the patient and have been documented as effective for treating Clostridium difficile infections (CDIs) and some other gastrointestinal disorders. However, the treatment has encountered regulatory hurdles preventing widespread uptake. We examined dominant representations of fecal transplants in Canadian media and found that fecal transplants are often represented as being inherently disgusting or distasteful (the "ick factor"). This "ick factor" is used to construct different messages about the treatment's social acceptability and legitimacy. We conclude that an over-emphasis on the "ick factor" constrains public discourse from a more nuanced discussion of the social challenges, scientific concerns, and regulatory issues surrounding the treatment.

Interactions Between the Gastrointestinal Microbiome and Clostridium difficile

Antibiotics have significant and long-lasting effects on the intestinal microbiota and consequently reduce colonization resistance against pathogens, including Clostridium difficile. By altering the community structure of the gut microbiome, antibiotics alter the intestinal metabolome, which includes both host- and microbe-derived metabolites. The mechanisms by which antibiotics reduce colonization resistance against C. difficile are unknown yet important for development of preventative and therapeutic approaches against this pathogen. This review focuses on how antibiotics alter the structure of the gut microbiota and how this alters microbial metabolism in the intestine. Interactions between gut microbial products and C. difficile spore germination, growth, and toxin production are discussed. New bacterial therapies to restore changes in bacteria-driven intestinal metabolism following antibiotics will have important applications for treatment and prevention of C. difficile infection.

Effects of tigecycline and vancomycin administration on established Clostridium difficile infection

The glycylcycline antibiotic tigecycline was approved in 2005 for the treatment of complicated skin and soft tissue infections and complicated intra-abdominal infections. Tigecycline is broadly active against both Gram-negative and Gram-positive microorganisms, including Clostridium difficile. Tigecycline has a low MIC against C. difficile in vitro and thus may represent an alternate treatment for C. difficile infection (CDI). To assess the use of tigecycline for treatment of established CDI, 5- to 8-week-old C57BL/6 mice were colonized with C. difficile strain 630. After C. difficile colonization was established, mice (n = 10 per group) were treated with either a 5-day course of tigecycline (6.25 mg/kg every 12 h subcutaneously) or a 5-day course of vancomycin (0.4 mg/ml in drinking water) and compared to infected, untreated control mice. Mice were evaluated for clinical signs of CDI throughout treatment and at 1 week posttreatment to assess potential for disease development. Immediately following a treatment course, C. difficile was not detectable in the feces of vancomycin-treated mice but remained detectable in feces from tigecycline-treated and untreated control mice. Toxin activity and histopathological inflammation and edema were observed in the ceca and colons of untreated mice; tigecycline- and vancomycin-treated mice did not show such changes directly after treatment. One week after the conclusion of either antibiotic treatment, C. difficile load, toxin activity, and histopathology scores increased in the cecum and colon, indicating that C. difficile-associated disease occurred. In vitro growth studies confirmed that subinhibitory concentrations of tigecycline were able to suppress toxin activity and spore formation of C. difficile, whereas vancomycin did not. Taken together, these data show how tigecycline is able to alter C. difficile pathogenesis in a mouse model of CDI.

Two-week treatment with proton pump inhibitor is sufficient for healing post endoscopic submucosal dissection ulcers

AIM: To investigate the optimum period of treatment for post endoscopic submucosal dissection (ESD) ulcers.

METHODS: Patients who underwent ESD for gastric cancer were randomized to two groups and treated with esomeprazole 20 mg per day for 4 wk (4W group) or 2 wk (2W group). At 4 wk after ESD, we measured the size of the artificial ulcers by endoscopy and determined the ulcer healing rate, compared with the size of the ESD specimens. This randomized controlled trial study was approved by our ethics committee and registered in the UMIN Clinical Trial Registry.

RESULTS: A total of 60 consecutive patients were included in the study. All patients received rebamipide 300 mg per day for 4 wk. One patient in 2W group who showed bleeding within two weeks and received endoscopic treatment was excluded from further analysis. The numbers of patients with ulcers in the healing/scar stage in the 2W and 4W groups at 4 wk after ESD were 20/6 and 28/5, respectively, with no significant difference. The ulcer healing rate in the 2W and 4W groups were 96.1% [95% confidence interval (CI): 94.6%-97.55] vs 94.8% (95%CI: 92.6%-97.1%), respectively, with no statistical difference (UMIN000006951).

CONCLUSION: Two-wk treatment with a proton pump inhibitor is as effective as four-week treatment for healing post ESD ulcers.

Systemically administered IgG anti-toxin antibodies protect the colonic mucosa during infection with Clostridium difficile in the piglet model

The use of anti-toxin human monoclonal antibodies (HMab) as treatment for C. difficile infection has been investigated in animal models and human clinical trials as an alternative to or in combination with traditional antibiotic therapy. While HMab therapy appears to be a promising option, how systemically administered IgG antibodies protect the colonic mucosa during Clostridium difficile infection is unknown. Using the gnotobiotic piglet model of Clostridium difficile infection, we administered a mixture of anti-TcdA and anti-TcdB HMabs systemically to piglets infected with either pathogenic or non-pathogenic C. difficile strains. The HMabs were present throughout the small and large intestinal tissue of both groups, but significant HMabs were present in the lumen of the large intestines only in the pathogenic strain-infected group. Similarly, HMabs measured in the large intestine over a period of 2-4 days following antibody administration were not significantly different over time in the gut mucosa among the groups, but concentrations in the lumen of the large intestine were again consistently higher in the pathogenic strain-infected group. These results indicate that systemically administered HMab IgG reaches the gut mucosa during the course of CDI, protecting the host against systemic intoxication, and that leakage through the damaged colon likely protects the mucosa from further damage, allowing initiation of repair and recovery.

Clostridium difficile infection in patients with ileal pouches

Clostridium difficile (C. difficile) infection (CDI) following total proctocolectomy and ileal pouch-anal anastomosis has been increasingly recognized over the past 5 years. CDI of the ileal pouch has been recognized in ∼10% of symptomatic patients seen at a tertiary referral center for pouch dysfunction. In contrast to colonic CDI in the general population or in patients with inflammatory bowel disease, postoperative antibiotic exposure and the use of immunosuppressive agents or proton pump inhibitors do not appear to be associated with CDI of the pouch. Male gender, recent hospitalization, and presurgery antibiotic use were shown to be risk factors for ileal pouch CDI. The ileal pouch may be susceptible to CDI owing to similarities with the colon at physiological and structural levels. Postcolectomy CDI likely represents a spectrum of disease processes, varying from asymptomatic colonization to severe symptomatic infection. CDI should be considered in any patient with an ileal pouch presenting with a change in "normal" symptom pattern or treatment-refractory disease. Sensitive and specific methods for the detection of CDI are available, and pouchoscopy is a valuable tool in the evaluation of the patient with symptomatic CDI of the pouch. At a referral center for pouch dysfunction, vancomycin is used as the first-line therapy for ileal pouch CDI. Fecal microbiota transplantation may find use in the management of severe or antibiotic refractory CDI-related pouchitis.

Hematologic diseases: High risk of Clostridium difficile associated diarrhea

AIM: To investigate the incidence and clinical outcome of Clostridium difficile (C. difficile) associated diarrhea (CDAD) in patients with hematologic disease.

METHODS: We retrospectively reviewed the medical records of patients who underwent C. difficile testing in a tertiary hospital in 2011. The incidence and risk factors for CDAD and its clinical course including recurrence and mortality were assessed in patients with hematologic disease and compared with those in patients with nonhematologic disease.

RESULTS: About 320 patients were diagnosed with CDAD (144 patients with hematologic disease; 176 with nonhematologic disease). The incidence of CDAD in patients with hematologic disease was estimated to be 36.7 cases/10000 patient hospital days, which was higher than the 5.4 cases/10000 patient hospital days in patients with nonhematologic disease. Recurrence of CDAD was more frequent in patients with hematologic disease compared to those with nonhematologic disease (18.8% vs 8.5%, P < 0.01), which was associated with higher re-use of causative antibiotics for CDAD. Mortality due to CDAD did not differ between the two groups. Multivariate analysis showed that intravenous immunoglobulin was the only significant factor associated with a lower rate of recurrence of CDAD in patients with hematologic disease.

CONCLUSION: The incidence and recurrence of CDAD was higher in patients with hematologic disease than in those with nonhematologic disease.

Clinical update for the diagnosis and treatment of Clostridium difficile infection

Clostridium difficile infection (CDI) presents a rapidly evolving challenge in the battle against hospital-acquired infections. Recent advances in CDI diagnosis and management include rapid changes in diagnostic approach with the introduction of newer tests, such as detection of glutamate dehydrogenase in stool and polymerase chain reaction to detect the gene for toxin production, which will soon revolutionize the diagnostic approach to CDI. New medications and multiple medical society guidelines have introduced changing concepts in the definitions of severity of CDI and the choice of therapeutic agents, while rapid expansion of data on the efficacy of fecal microbiota transplantation heralds a revolutionary change in the management of patients suffering multiple relapses of CDI. Through a comprehensive review of current medical literature, this article aims to offer an intensive review of the current state of CDI diagnosis, discuss the strengths and limitations of available laboratory tests, compare both current and future treatments options and offer recommendations for best practice strategies.

Diagnosis of Clostridium difficile infection: an ongoing conundrum for clinicians and for clinical laboratories

Clostridium difficile is a formidable nosocomial and community-acquired pathogen, causing clinical presentations ranging from asymptomatic colonization to self-limiting diarrhea to toxic megacolon and fulminant colitis. Since the early 2000s, the incidence of C. difficile disease has increased dramatically, and this is thought to be due to the emergence of new strain types. For many years, the mainstay of C. difficile disease diagnosis was enzyme immunoassays for detection of the C. difficile toxin(s), although it is now generally accepted that these assays lack sensitivity. A number of molecular assays are commercially available for the detection of C. difficile. This review covers the history and biology of C. difficile and provides an in-depth discussion of the laboratory methods used for the diagnosis of C. difficile infection (CDI). In addition, strain typing methods for C. difficile and the evolving epidemiology of colonization and infection with this organism are discussed. Finally, considerations for diagnosing C. difficile disease in special patient populations, such as children, oncology patients, transplant patients, and patients with inflammatory bowel disease, are described. As detection of C. difficile in clinical specimens does not always equate with disease, the diagnosis of C. difficile infection continues to be a challenge for both laboratories and clinicians.

Impact of changes in Clostridium difficile testing practices on stool rejection policies and C. difficile positivity rates across multiple laboratories in the United States

We describe the adoption of nucleic acid amplification tests (NAAT) for Clostridium difficile diagnosis and their impact on stool rejection policies and C. difficile positivity rates. Of the laboratories with complete surveys, 51 (43%) reported using NAAT in 2011. Laboratories using NAAT had stricter rejection policies and increased positivity rates.

Clostridium difficile glutamate dehydrogenase is a secreted enzyme that confers resistance to H2O2

Clostridium difficile produces an NAD-specific glutamate dehydrogenase (GDH), which converts l-glutamate into α-ketoglutarate through an irreversible reaction. The enzyme GDH is detected in the stool samples of patients with C. difficile-associated disease and serves as one of the diagnostic tools to detect C. difficile infection (CDI). We demonstrate here that supernatant fluids of C. difficile cultures contain GDH. To understand the role of GDH in the physiology of C. difficile, an isogenic insertional mutant of gluD was created in strain JIR8094. The mutant failed to produce and secrete GDH as shown by Western blot analysis. Various phenotypic assays were performed to understand the importance of GDH in C. difficile physiology. In TY (tryptose yeast extract) medium, the gluD mutant grew slower than the parent strain. Complementation of the gluD mutant with the functional gluD gene reversed the growth defect in TY medium. The presence of extracellular GDH may have a functional role in the pathogenesis of CDI. In support of this assumption we found higher sensitivity to H2O2 in the gluD mutant as compared to the parent strain. Complementation of the gluD mutant with the functional gluD gene reversed the H2O2 sensitivity.

Clostridium difficile vertebral osteomyelitis

Clostridium difficile is the most common cause of antibiotic-associated diarrhea, and it occasionally causes extraintestinal infections. We present a case of C. difficile-associated diarrhea that led to vertebral osteomyelitis associated with hardware. The osteomyelitis became symptomatic 2 years after the initial diarrheal event. C. difficile recovered from internal hardware sites cannot simply be regarded as a contaminant but should be treated.

Excess risk of Clostridium difficile infection in ovarian cancer is related to exposure to broad-spectrum antibiotics

PURPOSE

The purpose of the study was to determine if a diagnosis of ovarian cancer is independently associated with an increased risk of Clostridium difficile infection (CDI).

METHODS

The University HealthSystem Consortium database was queried to perform a retrospective cohort study of women with and without ovarian cancer who were diagnosed with CDI. Inpatients undergoing total hysterectomy from 2008 to 2012 were studied. Ovarian cancer patients were compared to non-ovarian cancer patients to evaluate relative risk (RR) of CDI. Adjustment was made for known or suspected CDI risk factors to determine RR of CDI independent of these variables.

RESULTS

In this study, 115,203 patients were included. CDI was reported in 0.80 % of ovarian cancer patients and in 0.31 % of non-ovarian cancer patients (RR = 2.50; 95 % confidence interval (CI) = 2.02 to 3.35). Stratification by age, presence of other comorbidities, or administration of antineoplastic drugs did not significantly modify the elevated risk associated with ovarian cancer. Significantly increased risk in ovarian cancer patients was no longer observed after controlling for broad-spectrum antibiotic administration (RR = 1.28, 95 % CI = 0.39 to 4.13). Compared to non-ovarian cancer patients, ovarian cancer patients were more frequently treated with broad-spectrum antibiotics, had a 39 % longer mean duration of therapy, and had 2.5-fold greater mean total exposure to broad-spectrum antibiotics.

CONCLUSIONS

After adjustment for antibiotic use, ovarian cancer patients are not at excess risk of CDI. Additional studies are needed to understand the patterns of broad-spectrum antibiotic prescription for ovarian cancer patients leading to increased exposure. If feasible, reduction of this exposure may decrease morbidity in this population.

MBX-500 is effective for treatment of Clostridium difficile infection in gnotobiotic piglets

The novel antibiotic MBX-500, dosed at 100, 200, or 400 mg/kg twice daily for 7 days, was evaluated for the treatment of Clostridium difficile infection (CDI) in the gnotobiotic pig model. MBX-500 increased survival at all doses and at high doses improved clinical signs and reduced lesion severity, similar to vancomycin. Our results show that MBX-500 is an effective antibiotic for the treatment of diarrhea associated with CDI and prevents severe systemic disease.