Treatment of Clostridium difficile-associated disease

Immunogenicity and safety in rabbits of a Clostridioides difficile vaccine combining novel toxoids and a novel adjuvant

Clostridioides difficile infection (CDI) is a serious healthcare-associated disease, causing symptoms such as diarrhea and pseudomembranous colitis. The major virulence factors responsible for the disease symptoms are two secreted cytotoxic proteins, TcdA and TcdB. A parenteral vaccine based on formaldehyde-inactivated TcdA and TcdB supplemented with alum adjuvant, has previously been investigated in humans but resulted in an insufficient immune response. In search for an improved response, we investigated a novel toxin inactivation method and a novel, potent adjuvant. Inactivation of toxins by metal-catalyzed oxidation (MCO) was previously shown to preserve neutralizing epitopes and to annihilate reversion to toxicity. The immunogenicity and safety of TcdA and TcdB inactivated by MCO and combined with a novel carbohydrate fatty acid monosulphate ester-based (CMS) adjuvant were investigated in rabbits. Two or three intramuscular immunizations generated high serum IgG and neutralizing antibody titers against both toxins. The CMS adjuvant increased antibody responses to both toxins while an alum adjuvant control was effective only against TcdA. Systemic safety was evaluated by monitoring body weight, body temperature, and analysis of red and white blood cell counts shortly after immunization. Local safety was assessed by histopathologic examination of the injection site at the end of the study. Body weight gain was constant in all groups. Body temperature increased up to 1 ˚C one day after the first immunization but less after the second or third immunization. White blood cell counts, and percentage of neutrophils increased one day after immunization with CMS-adjuvanted vaccines, but not with alum. Histopathology of the injection sites 42 days after the last injection did not reveal any abnormal tissue reactions. From this study, we conclude that TcdA and TcdB inactivated by MCO and combined with CMS adjuvant demonstrated promising immunogenicity and safety in rabbits and could be a candidate for a vaccine against CDI.

Rapid Isothermal Detection of Pathogenic Clostridioides difficile Using Recombinase Polymerase Amplification

Nosocomial-associated diarrhea due to Clostridioides difficile infection (CDI) is diagnosed after sample precultivation by the detection of the toxins in enzyme immunoassays or via toxin gene nucleic acid amplification. Rapid and direct diagnosis is important for targeted treatment to prevent severe cases and recurrence. We developed two singleplex and a one-pot duplex fluorescent 15 min isothermal recombinase polymerase amplification (RPA) assays targeting the toxin genes A and B (tcdA and tcdB). Furthermore, we adapted the singleplex RPA to a 3D-printed microreactor device. Analytical sensitivity was determined using a DNA standard and DNA extracts of 20 C. difficile strains with different toxinotypes. Nineteen clostridial and gastrointestinal bacteria strains were used to determine analytical specificity. Adaptation of singleplex assays to duplex assays in a 50 μL volume required optimized primer and probe concentrations. A volume reduction by one-fourth (12.4 μL) was established for the 3D-printed microreactor. Mixing of RPA was confirmed as essential for optimal analytical sensitivity. Detection limits (LOD) ranging from 119 to 1411 DNA molecules detected were similar in the duplex tube format and in the singleplex 3D-printed microreactor format. The duplex RPA allows the simultaneous detection of both toxins important for the timely and reliable diagnosis of CDI. The 3D-printed reaction chamber can be developed into a microfluidic lab-on-a-chip system use at the point of care.

Interactions of metronidazole and chloramphenicol with myoglobin: Crystal structure of a Mb-acetamide product

Nitroorganics present a general concern for a safe environment due to their health hazards. However, some nitroorganics such as metronidazole (Mtz) and chloramphenicol (CAM) also possess medicinal value. Mtz and CAM can undergo reductive bioactivation presumably via their nitroso derivatives. We show, using UV-vis spectroscopy, that sperm whale myoglobin (swMb) and its distal pocket mutants retaining H-bonding capacity react with Mtz in the presence of dithionite to generate products with spectra suggestive of the Fe-bound nitroso (Fe-RNO; λmax ~420 nm) forms. We have crystallized and solved the X-ray crystal structure of an H64Q swMb-acetamide compound to 1.76 Å resolution; formation of this compound results from the serendipitous crystallographic trapping, by the heme center, of acetamide from the reductive decomposition of Mtz. Only one of the swMb proteins, namely H64Q swMb with a relatively flexible Gln64 residue, reacted with CAM presumably due to the bulky nature of CAM that generally may restrict its access to the heme site.

Auranofin and Baicalin Inhibit Clostridioides difficile Growth and Sporulation: An In vitro Study

Clostridioides difficile is a principal cause of hospital-acquired gastrointestinal infections, with sporulation and toxin production being key determinants in the disease pathogenesis. Although infections have been escalating and the complications can be life-threatening, the narrow pipeline of approved therapeutics has not witnessed an equivalent surge. With the unfolding of worrisome mutations and antimicrobial resistance, attention has been drawn to either discovering new therapeutics, or even better, repurposing already available ones. Consequently, this study was undertaken to assess the anti-clostridial activity of auranofin, an anti-rheumatic FDA-approved therapeutic; and baicalin, a natural flavone glycoside with reported anti-microbial potential. In comparison with vancomycin, the in vitro efficacy of auranofin and baicalin was tested against hypervirulent C. difficile (BAA-1870TM). Broth suspensions were prepared with and without the three agents and anaerobically incubated. At 24- and 48-hours post-incubation, serial dilutions were prepared and inoculated onto agar plates. Viable cell counts and viable spore counts were then quantified. Meanwhile, toxin production was assessed via ELISA. At a concentration as low as 3 μg/mL, auranofin demonstrated a potent anti-clostridial activity. Both auranofin and baicalin exhibited a remarkable reduction in C. difficile viable cell counts (P-value 0.03 for each) and spore counts (P-values 0.023 and 0.045 respectively). While auranofin and baicalin proved to be non-inferior to vancomycin as inhibitors of C. difficile growth, both drugs proved to be superior to vancomycin in decreasing the spore counts 48-hours post inoculation. Additionally, auranofin markedly reduced C. difficile toxin production (P-value 0.021); a feature that was deficient in both baicalin and vancomycin. To enrich the currently limited repertoire of anti-clostridial drugs, further research is encouraging to compare between the in vivo efficacy of auranofin and that of baicalin. Both agents represent promising approaches that could address the unfulfilled needs in controlling C. difficile infection.

Clostridioides difficile: Current overview and future perspectives

The most common world-wide cause of antibiotic-associated infectious diarrhea and colitis is the toxin producing bacterium, Clostridioides difficile (C. difficile). Here we review the background and characteristics of the bacterium and the toxins produced together with the epidemiology and the complex pathogenesis that leads to a broad clinical spectrum of disease. The review describes the difficulties faced in obtaining a quick and accurate diagnosis despite the range of sensitive and specific diagnostic tools available. We also discuss the problem of disease recurrence and the importance of disease prevention. The high rates of infection recurrence mean that treatment strategies are constantly under review and we outline the diverse treatment options that are currently in use and explore the emerging treatment options of pulsed antibiotic use, microbial replacement therapies and the use of monoclonal antibodies. We summarize the future direction of treatment strategies which include the development of novel antibiotics, the administration of oral polyclonal antibody formulations, the use of vaccines, the administration of competitive non-toxigenic spores and the neutralization of antibiotics at the microbiota level. Future successful treatments will likely involve a combination of therapies to provide the most effective and robust approach to C. difficile management.

Cationic Peptidomimetic Amphiphiles Having a N-Aryl- or N-Naphthyl-1,2,3-Triazole Core Structure Targeting Clostridioides (Clostridium) difficile: Synthesis, Antibacterial Evaluation, and an In Vivo C. difficile Infection Model

Clostridioides (also known as Clostridium) difficile is a Gram-positive anaerobic, spore producing bacterial pathogen that causes severe gastrointestinal infection in humans. The current chemotherapeutic options are inadequate, expensive, and limited, and thus inexpensive drug treatments for C. difficile infection (CDI) with improved efficacy and specificity are urgently needed. To improve the solubility of our cationic amphiphilic 1,1′-binaphthylpeptidomimetics developed earlier that showed promise in an in vivo murine CDI model we have synthesized related compounds with an N-arytriazole or N-naphthyltriazole moiety instead of the 1,1′-biphenyl or 1,1′-binaphthyl moiety. This modification was made to increase the polarity and thus water solubility of the overall peptidomimetics, while maintaining the aromatic character. The dicationic N-naphthyltriazole derivative 40 was identified as a C. difficile-selective antibacterial with MIC values of 8 µg/mL against C. difficile strains ATCC 700057 and 132 (both ribotype 027). This compound displayed increased water solubility and reduced hemolytic activity (32 µg/mL) in an in vitro hemolysis assay and reduced cytotoxicity (CC₅₀ 32 µg/mL against HEK293 cells) relative to lead compound 2. Compound 40 exhibited mild efficacy (with 80% survival observed after 24 h compared to the DMSO control of 40%) in an in vivo murine model of C. difficile infection by reducing the severity and slowing the onset of disease.

Bioinformatics-driven discovery of novel Clostridioides difficile lysins and experimental comparison with highly active benchmarks

Clostridioides difficile is the single most deadly bacterial pathogen in the United States, and its global prevalence and outsized health impacts underscore the need for more effective therapeutic options. Towards this goal, a novel group of modified peptidoglycan hydrolases with significant in vitro bactericidal activity have emerged as potential candidates for treating C. difficile infections (CDI). To date, discovery and development efforts directed at these CDI-specific lysins have been limited, and in particular there has been no systematic comparison of known or newly discovered lysin candidates. Here, we detail bioinformatics-driven discovery of six new anti-C. difficile lysins belonging to the amidase-3 family of enzymes, and we describe experimental comparison of their respective catalytic domains (CATs) with highly active CATs from the literature. Our quantitative analyses include metrics for expression level, inherent antibacterial activity, breadth of strain selectivity, killing of germinating spores, and structural and functional measures of thermal stability. Importantly, prior studies have not examined stability as a performance metric, and our results show that the panel of eight enzymes possess widely variable thermal denaturation temperatures and resistance to heat inactivation, including some enzymes that exhibit marginal stability at body temperature. Ultimately, no single enzyme dominated with respect to all performance measures, suggesting the need for a balanced assessment of lysin properties during efforts to find, engineer, and develop candidates with true clinical potential.

Characterization of an Endolysin Targeting Clostridioides difficile That Affects Spore Outgrowth

Clostridioides difficile is a spore-forming enteric pathogen causing life-threatening diarrhoea and colitis. Microbial disruption caused by antibiotics has been linked with susceptibility to, and transmission and relapse of, C. difficile infection. Therefore, there is an urgent need for novel therapeutics that are effective in preventing C. difficile growth, spore germination, and outgrowth. In recent years bacteriophage-derived endolysins and their derivatives show promise as a novel class of antibacterial agents. In this study, we recombinantly expressed and characterized a cell wall hydrolase (CWH) lysin from C. difficile phage, phiMMP01. The full-length CWH displayed lytic activity against selected C. difficile strains. However, removing the N-terminal cell wall binding domain, creating CWH_351—656, resulted in increased and/or an expanded lytic spectrum of activity. C. difficile specificity was retained versus commensal clostridia and other bacterial species. As expected, the putative cell wall binding domain, CWH_1—350, was completely inactive. We also observe the effect of CWH_351—656 on preventing C. difficile spore outgrowth. Our results suggest that CWH_351—656 has therapeutic potential as an antimicrobial agent against C. difficile infection.

Therapeutic Effect of Chitosan Nanoparticles and Metronidazole in Treatment of Experimentally Giardiasis Infected Hamsters

Background:

The present study aimed to assess the therapeutic effect of chitosan nanoparticles and metronidazole against Giardia lamblia as well as evaluate the efficacy of loading metronidazole on chitosan nanoparticles.

Methods:

This study was carried out at medical Parasitology Department, Faculty of Medicine, Zagazig University and Theodor Bilharz Research institute (TBRI) from February 2019 to February 2020 on 45 hamsters. They were divided into 5 groups 9 hamsters each: Group A non-infected hamsters, Group B infected control group, Group C, D and E infected with G. lamblia and treated with Chitosan nanoparticles (CsNPs), metronidazole (MTZ) and metronidazole-loaded chitosan nanoparticles (MTZ-CsNPs) respectively.

Results:

The highest percentage of reduction in the Giardia cyst and trophozoite counts were in group that received MTZ-CsNPs (94.69%, 94.29%). Lower percentages of reduction were recorded for MTZ treated group (90.15%, 89.52%) and CsNPs treated group (63.64%, 75.24%). Histopathological examination showed marked healing of intestinal mucosa after treatment with MTZ-CsNPs.

Conclusion:

CsNPs showed a therapeutic effect against Giardia infection in hamsters. Loading of metronidazole on chitosan nanoparticles enhanced therapeutic effect of both CsNPs as well as metronidazole.

Protease-stable DARPins as promising oral therapeutics

Clostridioides difficile is an enteric bacterium whose exotoxins, TcdA and TcdB, inactivate small GTPases within the host cells, leading to bloody diarrhea. In prior work, our group engineered a panel of potent TcdB-neutralizing designed ankyrin repeat proteins (DARPin) as oral therapeutics against C. difficile infection. However, all these DARPins are highly susceptible to digestion by gut-resident proteases, i.e. trypsin and chymotrypsin. Close evaluation of the protein sequence revealed a large abundance of positively charged and aromatic residues in the DARPin scaffold. In this study, we significantly improved the protease stability of one of the DARPins, 1.4E, via protein engineering. Unlike 1.4E, whose anti-TcdB EC50 increased >83-fold after 1-hour incubation with trypsin (1 mg/ml) or chymotrypsin (0.5 mg/ml), the best progenies-T10-2 and T10b-exhibit similar anti-TcdB potency as their parent in PBS regardless of protease treatment. The superior protease stability of T10-2 and T10b is attributed to the removal of nearly all positively charged and aromatic residues except those directly engaged in target binding. Furthermore, T10-2 was found to retain significant toxin-neutralization ability in ex vivo cecum fluid and can be easily detected in mouse fecal samples upon oral administration. Both T10-2 and T10b enjoy a high thermo- and chemo-stability and can be expressed very efficiently in Escherichia coli (>100 mg/l in shaker flasks). We believe that, in additional to their potential as oral therapeutics against C. difficile infection, T10-2 and T10b can also serve as a new generation DARPin scaffold with superior protease stability.

Benzyl and benzoyl benzoic acid inhibitors of bacterial RNA polymerase-sigma factor interaction

Transcription is an essential biological process in bacteria requiring a core enzyme, RNA polymerase (RNAP). Bacterial RNAP is catalytically active but requires sigma (σ) factors for transcription of natural DNA templates. σ factor binds to RNAP to form a holoenzyme which specifically recognizes a promoter, melts the DNA duplex, and commences RNA synthesis. Inhibiting the binding of σ to RNAP is expected to inhibit bacterial transcription and growth. We previously identified a triaryl hit compound that mimics σ at its major binding site of RNAP, thereby inhibiting the RNAP holoenzyme formation. In this study, we modified this scaffold to provide a series of benzyl and benzoyl benzoic acid derivatives possessing improved antimicrobial activity. A representative compound demonstrated excellent activity against Staphylococcus epidermidis with minimum inhibitory concentrations reduced to 0.5 μg/mL, matching that of vancomycin. The molecular mechanism of inhibition was confirmed using biochemical and cellular assays. Low cytotoxicity and metabolic stability of compounds demonstrated the potential for further studies.

New Host-Directed Therapeutics for the Treatment of Clostridioides difficile Infection

Frequent and excessive use of antibiotics primes patients to Clostridioides difficile infection (CDI), which leads to fatal pseudomembranous colitis, with limited treatment options. In earlier reports, we used a drug repurposing strategy and identified amoxapine (an antidepressant), doxapram (a breathing stimulant), and trifluoperazine (an antipsychotic), which provided significant protection to mice against lethal infections with several pathogens, including C. difficile However, the mechanisms of action of these drugs were not known. Here, we provide evidence that all three drugs offered protection against experimental CDI by reducing bacterial burden and toxin levels, although the drugs were neither bacteriostatic nor bactericidal in nature and had minimal impact on the composition of the microbiota. Drug-mediated protection was dependent on the presence of the microbiota, implicating its role in evoking host defenses that promoted protective immunity. By utilizing transcriptome sequencing (RNA-seq), we identified that each drug increased expression of several innate immune response-related genes, including those involved in the recruitment of neutrophils, the production of interleukin 33 (IL-33), and the IL-22 signaling pathway. The RNA-seq data on selected genes were confirmed by quantitative real-time PCR (qRT-PCR) and protein assays. Focusing on amoxapine, which had the best anti-CDI outcome, we demonstrated that neutralization of IL-33 or depletion of neutrophils resulted in loss of drug efficacy. Overall, our lead drugs promote disease alleviation and survival in the murine model through activation of IL-33 and by clearing the pathogen through host defense mechanisms that critically include an early influx of neutrophils.IMPORTANCEClostridioides difficile is a spore-forming anaerobic bacterium and the leading cause of antibiotic-associated colitis. With few therapeutic options and high rates of disease recurrence, the need to develop new treatment options is urgent. Prior studies utilizing a repurposing approach identified three nonantibiotic Food and Drug Administration-approved drugs, amoxapine, doxapram, and trifluoperazine, with efficacy against a broad range of human pathogens; however, the protective mechanisms remained unknown. Here, we identified mechanisms leading to drug efficacy in a murine model of lethal C. difficile infection (CDI), advancing our understanding of the role of these drugs in infectious disease pathogenesis that center on host immune responses to C. difficile Overall, these studies highlight the crucial involvement of innate immune responses, as well as the importance of immunomodulation as a potential therapeutic option to combat CDI.

Seasonality and community interventions in a mathematical model of Clostridium difficile transmission

BACKGROUND

Clostridium difficile infection (CDI) is the leading cause of antibiotic-associated diarrhoea with peak incidence in late winter or early autumn. Although CDI is commonly associated with hospitals, community transmission is important.

AIM

To explore potential drivers of CDI seasonality and the effect of community-based interventions to reduce transmission.

METHODS

A mechanistic compartmental model of C. difficile transmission in a hospital and surrounding community was used to determine the effect of reducing transmission or antibiotic prescriptions in these settings. The model was extended to allow for seasonal antibiotic prescriptions and seasonal transmission.

FINDINGS

Modelling antibiotic seasonality reproduced the seasonality of CDI, including approximate magnitude (13.9-15.1% above annual mean) and timing of peaks (0.7-1.0 months after peak antibiotics). Halving seasonal excess prescriptions reduced the incidence of CDI by 6-18%. Seasonal transmission produced larger seasonal peaks in the prevalence of community colonization (14.8-22.1% above mean) than seasonal antibiotic prescriptions (0.2-1.7% above mean). Reducing transmission from symptomatic or hospitalized patients had little effect on community-acquired CDI, but reducing transmission in the community by ≥7% or transmission from infants by ≥30% eliminated the pathogen. Reducing antibiotic prescription rates led to approximately proportional reductions in infections, but limited reductions in the prevalence of colonization.

CONCLUSION

Seasonal variation in antibiotic prescription rates can account for the observed magnitude and timing of C. difficile seasonality. Even complete prevention of transmission from hospitalized patients or symptomatic patients cannot eliminate the pathogen, but interventions to reduce transmission from community residents or infants could have a large impact on both hospital- and community-acquired infections.

Cationic biaryl 1,2,3-triazolyl peptidomimetic amphiphiles targeting Clostridioides (Clostridium) difficile: Synthesis, antibacterial evaluation and an in vivo C. difficile infection model

Clostridioides (formerly Clostridium) difficile is a Gram-positive anaerobic bacterial pathogen that causes severe gastrointestinal infection in humans. The current chemotherapeutic options are vastly inadequate, expensive and limited; this results in an exorbitant medical and financial burden. New, inexpensive chemotherapeutic treatments for C. difficile infection with improved efficacy are urgently needed. A streamlined synthetic pathway was developed to allow access to 38 novel mono- and di-cationic biaryl 1,2,3-triazolyl peptidomimetics with increased synthetic efficiency, aqueous solubility and enhanced antibacterial efficacy. The monocationic arginine derivative 28 was identified as a potent, Gram-positive selective antibacterial with MIC values of 4 μg/mL against methicillin-resistant Staphylococcus aureus and 8 μg/mL against C. difficile. Furthermore, the dicationic bis-triazole analogue 50 was found to exhibit broad-spectrum activity with substantial Gram-negative efficacy against Acinetobacter baumannii (8 μg/mL), Pseudomonas aeruginosa (8 μg/mL) and Klebsiella pneumoniae (16 μg/mL); additionally, compound 50 displayed reduced haemolytic activity (<13%) in an in vitro haemolysis assay. Membrane-disruption assays were conducted on selected derivatives to confirm the membrane-active mechanism of action inherent to the synthesized amphiphilic compounds. A comparative solubility assay was developed and utilized to optimize the aqueous solubility of the compounds for in vivo studies. The biaryl peptidomimetics 28 and 67 were found to exhibit significant efficacy in an in vivo murine model of C. difficile infection by reducing the severity and slowing the onset of disease.

Clostridium difficile, the Difficult "Kloster" Fuelled by Antibiotics

Clostridium difficile is normally present in low numbers in a healthy adult gastro-intestinal tract (GIT). Drastic changes in the microbial population, e.g., dysbiosis caused by extensive treatment with antibiotics, stimulates the growth of resistant strains and the onset of C. difficile infection (CDI). Symptoms of infection varies from mild diarrhea to colitis (associated with dehydration and bleeding), pseudomembranous colitis with yellow ulcerations in the mucosa of the colon, to fulminant colitis (perforation of the gut membrane), and multiple organ failure. Inflamed epithelial cells and damaged mucosal tissue predisposes the colon to other opportunistic pathogens such as Clostridium perfringens, Staphylococcus aureus, Klebsiella oxytoca, Candida spp., and Salmonella spp. This may lead to small intestinal bacterial overgrowth (SIBO), sepsis, toxic megacolon, and even colorectal cancer. Many stains of C. difficile are resistant to metronidazole and vancomycin. Vaccination may be an answer to CDI, but requires more research. Success in treatment with probiotics depends on the strains used. Oral or rectal fecal transplants are partly effective, as spores in the small intestine may germinate and colonize the colon. The effect of antibiotics on C. difficile and commensal gut microbiota is summarized and changes in gut physiology are discussed. The need to search for non-antibiotic methods in the treatment of CDI and C. difficile-associated disease (CDAD) is emphasized.

Treatment of recurrent Clostridium difficile colitis: a narrative review

Clostridium difficile is a gram-positive, spore-forming, obligate anaerobic bacillus that was originally isolated from the stool of a healthy neonate in 1935. In high-income countries, C. difficile is the most common cause of infectious diarrhoea in hospitalized patients. The incidence of C. difficile infection in the USA has increased markedly since 2000, with hospitalizations for C. difficile infections in non-pregnant adults doubling between 2000 and 2010. Between 20% and 35% of patients with C. difficile infection will fail initial antibiotic treatment and, of these, 40-60% will have a second recurrence. Recurrence of C. difficile infection after initial treatment causes substantial morbidity and is a major burden on health care systems. In this article, current treatments for recurrent C. difficile infection are reviewed and future directions explored. These include the use of antibiotics, probiotics, donor faecal transplants, anion resins, secondary bile acids or anti-toxin antibodies.

Healthcare-Associated Clostridium difficile Infections are Sustained by Disease from the Community

Clostridium difficile infections (CDIs) are some of the most common hospital-associated infections worldwide. Approximately 5% of the general population is colonised with the pathogen, but most are protected from disease by normal intestinal flora or immune responses to toxins. We developed a stochastic compartmental model of CDI in hospitals that captures the condition of the host's gut flora and the role of adaptive immune responses. A novel, derivative-based method for sensitivity analysis of individual-level outcomes was developed and applied to the model. The model reproduced the observed incidence and recurrence rates for hospitals with high and moderate incidence of hospital-acquired CDI. In both scenarios, the reproduction number for within-hospital transmission was less than 1 (0.67 and 0.44, respectively), but the proportion colonised with C. difficile at discharge (7.3 and 6.1%, respectively) exceeded the proportion colonised at admission (5%). The transmission and prevalence of CDI were most sensitive to the average length of stay and the transmission rate of the pathogen. Recurrent infections were most strongly affected by the treatment success rate and the immune profile of patients. Transmission within hospitals is substantial and leads to a net export of colonised individuals to the broader community. However, within-hospital transmission alone is insufficient to sustain endemic conditions in hospitals without the constant importation of colonised individuals. Improved hygiene practices to reduce transmission from symptomatic and asymptomatic individuals and reduced length of stay are most likely to reduce within-hospital transmission and infections; however, these interventions are likely to have a smaller effect on the probability of recurrence. Immunising inpatients against the toxins produced by C. difficile will reduce the incidence of CDI but may increase transmission.

Clostridium difficile Infection in Contemporary Urologic Practice

Clostridium difficile infection (CDI) is a high-impact hospital-acquired condition and a chief driver of excess morbidity, mortality, and treatment cost. The diagnosis, treatment, and prevention of CDI are key components of any hospital-based practice. Urologists see a small percentage of all patients with CDI, but traditionally utilize antibiotic agents that put patients at risk of CDI. Urologic procedures making use of bowel have a significantly higher rate of CDI than other procedures. This review addresses concepts that practicing urologists should be aware of and should be able to put into practice to diagnose, treat, and prevent CDI.

Crystal structures of two nitroreductases from hypervirulent Clostridium difficile and functionally related interactions with the antibiotic metronidazole

Nitroreductases (NRs) are flavin mononucleotide (FMN)-dependent enzymes that catalyze the biotransformation of organic nitro compounds (RNO2; R = alkyl, aryl) to the nitroso RN=O, hydroxylamino RNHOH, or amine RNH2 derivatives. Metronidazole (Mtz) is a nitro-containing antibiotic that is commonly prescribed for lower-gut infections caused by the anaerobic bacterium Clostridium difficile. C. difficile infections rank number one among hospital acquired infections, and can result in diarrhea, severe colitis, or even death. Although NRs have been implicated in Mtz resistance of C. difficile, no NRs have been characterized from the hypervirulent R20291 strain of C. difficile. We report the first expression, purification, and three-dimensional X-ray crystal structures of two NRs from the C. difficile R20291 strain. The X-ray crystal structures of the two NRs were solved to 2.1 Å resolution. Their homodimeric structures exhibit the classic NR α+β fold, with each protomer binding one FMN cofactor near the dimer interface. Functional assays demonstrate that these two NRs metabolize Mtz with associated re-oxidation of the proteins. Importantly, these results represent the first isolation and characterization of NRs from the hypervirulent R20291 strain of relevance to organic RNO2 (e.g., Mtz) metabolism.

Structural Insights into Substrate Recognition by Clostridium difficile Sortase

Sortases function as cysteine transpeptidases that catalyze the covalent attachment of virulence-associated surface proteins into the cell wall peptidoglycan in Gram-positive bacteria. The substrate proteins targeted by sortase enzymes have a cell wall sorting signal (CWSS) located at the C-terminus. Up to date, it is still not well understood how sortases with structural resemblance among different classes and diverse species of bacteria achieve substrate specificity. In this study, we focus on elucidating the molecular basis for specific recognition of peptide substrate PPKTG by Clostridium difficile sortase B (Cd-SrtB). Combining structural studies, biochemical assays and molecular dynamics simulations, we have constructed a computational model of Cd-SrtB_ΔN26-PPKTG complex and have validated the model by site-directed mutagensis studies and fluorescence resonance energy transfer (FRET)-based assay. Furthermore, we have revealed that the fourth amino acid in the N-terminal direction from cleavage site of PPKTG forms specific interaction with Cd-SrtB and plays an essential role in configuring the peptide to allow more efficient substrate-specific cleavage by Cd-SrtB.

Perceptions of fecal microbiota transplantation for Clostridium difficile infection: factors that predict acceptance

Background

Despite the effectiveness of fecal microbiota transplantation (FMT) for treating recurrent Clostridium difficile (C. difficile) infection, some patients are reluctant to accept this therapy. Our study examined attitudes towards FMT and factors that contribute to patients’ acceptance of this treatment.

Methods

We distributed patient surveys at a Veterans Affairs hospital, a public hospital, and an academic faculty practice. Multivariable logistic regression was performed, adjusting for factors associated with FMT acceptance on univariate analysis and prior experience with C. difficile infection.

Results

Of 267 patients, only 12% knew of FMT prior to the survey, but 77% would undergo the procedure if medically indicated. On multivariable analysis, those with children and with college degrees or higher were more likely to agree to FMT (odds ratio [OR] 2.11, 95% confidence interval [CI] 1.02-4.35; OR 2.27, 95% CI 1.11-4.60 respectively). Sixty-five respondents (71%) chose colonoscopy as the preferred vehicle for FMT, while nasogastric tube was least preferred. Disease transmission was the most common concern (30%, n=242), and FMT success rate was the least selected concern (9.1%).

Conclusions

Most patients in a diverse sample of gastroenterology clinics had no prior knowledge of FMT, but were receptive to the procedure. Having children and higher education levels were predictors for FMT acceptance. Our findings suggest that barriers to FMT utilization may be overcome with counseling about safety concerns. More data on the risk of transmitting diseases or clinical characteristics, such as obesity, through FMT are needed and will be important for the acceptance of this procedure.

Recombinant Mucin-Type Fusion Proteins with a Galα1,3Gal Substitution as Clostridium difficile Toxin A Inhibitors

The capability of a recombinant mucin-like fusion protein, P-selectin glycoprotein ligand-1/mouse IgG2b (PSGL-1/mIgG2b), carrying Galα1,3Galβ1,4GlcNAc determinants to bind and inhibit Clostridium difficile toxin A (TcdA) was investigated. The fusion protein, produced by a glyco-engineered stable CHO-K1 cell line and designated C-PGC2, was purified by affinity and gel filtration chromatography from large-scale cultures. Liquid chromatography-mass spectrometry was used to characterize O-glycans released by reductive β-elimination, and new diagnostic ions to distinguish Galα1,3Gal- from Galα1,4Gal-terminated O-glycans were identified. The C-PGC2 cell line, which was 20-fold more sensitive to TcdA than the wild-type CHO-K1, is proposed as a novel cell-based model for TcdA cytotoxicity and neutralization assays. The C-PGC2-produced fusion protein could competitively inhibit TcdA binding to rabbit erythrocytes, making it a high-efficiency inhibitor of the hemagglutination property of TcdA. The fusion protein also exhibited a moderate capability for neutralization of TcdA cytotoxicity in both C-PGC2 and CHO-K1 cells, the former with and the latter without cell surface Galα1,3Galβ1,4GlcNAc sequences. Future studies in animal models of C. difficile infection will reveal its TcdA-inhibitory effect and therapeutic potential in C. difficile-associated diseases.

Age and gender differences in Clostridium difficile-related hospitalization trends in Madrid (Spain) over a 12-year period

This study aimed to analyze temporal trends by gender and age in Clostridium difficile infection (CDI)-related hospitalization rates in the Autonomous Community of Madrid (Spain) over a 12-year period. A population-based cross-sectional study of all hospital admissions with a CDI diagnosis from 2003 to 2014 was carried out. Annual age-specific hospitalization rates were calculated by gender. All the analyses were performed separately for total hospitalizations and hospitalizations with CDI as the primary diagnosis. Joinpoint regression models were used to analyze time trends. A total of 13,526 hospital discharges were identified (26.8 % with CDI as the primary diagnosis). In both sexes, a gradient in age-specific rates was observed, ranging in 2014 from 5.92 hospitalizations per 100,000 person-years in patients <15 years of age to 378.96 in patients ≥85 years of age. Since 2009, in the age group of 15-44 years, both men and women presented an increasing trend of around 18 %. A significantly increasing trend was detected in women of age 45-84 years, with an estimated annual percentage of change of 7.6 % in the age group of 45-64 years, and rounding with 4.5 % in the age group of 65-84 years. In men of age 45-64 years, the average annual percentage of increase was 4.7 %, and it was 21.1 % between 2010 and 2014 in the age group of 65-74 years. No trends were identified in the 85 years and over age group. Surveillance methods to assess trends by age group should be implemented. Preventive and therapeutic initiatives should remain a priority.

Clostridium difficile infection: A brief update on emerging therapies

PURPOSE

Established and investigational antibiotic, monoclonal antibody, vaccine, and microbe-based approaches to the prevention and treatment of Clostridium difficile infection (CDI) are reviewed.

SUMMARY

CDI is increasingly prevalent in the United States and other countries, particularly among hospitalized patients and the elderly, who are at high risk for potentially fatal CDI-related enterotoxic diarrhea. Established therapies for CDI such as vancomycin and metronidazole (an off-label use) are limited by poor efficacy and high recurrence rates. An investigational antibiotic with potent in vitro activity against all C. difficile strains (including the hypervirulent BI/NAP1/027 strain) has yielded encouraging results in early clinical trials. Another promising approach involves the use of monoclonal antibodies with selective activity against toxins responsible for CDI-associated diarrhea; in a small Phase II clinical trial, a single monoclonal antibody infusion in combination with vancomycin or metronidazole therapy was more effective than antibiotic therapy alone in preventing CDI relapse. Other emerging approaches to CDI treatment and prophylaxis include the use of vaccines against C. difficile toxins (several C. difficile-targeted vaccines are under development in Europe and the United States); microbe-based strategies such as fecal microbiota transplants, "microbial ecosystem therapeutics," and probiotic supplements; and an investigational encapsulated form of β-lactamase designed to prevent C. difficile colonization from progressing to CDI.

CONCLUSION

The current antibiotic therapies for CDI, mainly vancomycin and (off-label) metronidazole and the newer agent fidaxomicin, have limitations with respect to efficacy, recurrence rates, and adverse effects, but a variety of promising approaches are emerging.

Novel approaches to treating Clostridium difficile-associated colitis

Clostridium difficile is being recognized as a growing threat to many health-care systems. Epidemiology data shows that infection rates are soaring and the disease burden is increasing. Despite the efficacy of standard treatments, it is becoming evident that novel therapeutics will be required to tackle this disease. These new treatments aim to enhance the intestinal microbial barrier, activate the immune system and neutralize the toxins that mediate this disease. Many of these therapies are still in the beginning stages of investigation, however, in the next few years, more clinical data will become available to help implement many of these exciting new therapeutic approaches.

Using a Novel Lysin To Help Control Clostridium difficile Infections

As a consequence of excessive antibiotic therapies in hospitalized patients, Clostridium difficile, a Gram-positive anaerobic spore-forming intestinal pathogen, is the leading cause of hospital-acquired diarrhea and colitis. Drug treatments for these diseases are often complicated by antibiotic-resistant strains and a high frequency of treatment failures and relapse; therefore, novel nonantibiotic approaches may prove to be more effective. In this study, we recombinantly expressed a prophage lysin identified from a C. difficile strain, CD630, which we named PlyCD. PlyCD was found to have lytic activity against specific C. difficile strains. However, the recombinantly expressed catalytic domain of this protein, PlyCD1-174, displayed significantly greater lytic activity (>4-log kill) and a broader lytic spectrum against C. difficile strains while still retaining a high degree of specificity toward C. difficile versus commensal clostridia and other bacterial species. Our data also indicated that noneffective doses of vancomycin and PlyCD1-174 when combined in vitro could be significantly more bactericidal against C. difficile. In an ex vivo treatment model of mouse colon infection, we found that PlyCD1-174 functioned in the presence of intestinal contents, significantly decreasing colonizing C. difficile compared to controls. Together, these data suggest that PlyCD1-174 has potential as a novel therapeutic for clinical application against C. difficile infection, either alone or in combination with other preexisting treatments to improve their efficacy.

Mechanisms of hypervirulent Clostridium difficile ribotype 027 displacement of endemic strains: an epidemiological model

Following rapid, global clonal dominance of hypervirulent ribotypes, Clostridium difficile now constitutes the primary infectious cause of nosocomial diarrhoea. Evidence indicates at least three possible mechanisms of hypervirulence that facilitates the successful invasion of these atypical strains: 1) increased infectiousness relative to endemic strains; 2) increased symptomatic disease rate relative to endemic strains; and 3) an ability to outcompete endemic strains in the host’s gut. Stochastic simulations of an infection transmission model demonstrate clear differences between the invasion potentials of C. difficile strains utilising the alternative hypervirulence mechanisms, and provide new evidence that favours certain mechanisms (1 and 2) more than others (3). Additionally, simulations illustrate that direct competition between strains (inside the host’s gut) is not a prerequisite for the sudden switching that has been observed in prevailing ribotypes; previously dominant C. difficile strains can be excluded by hypervirulent ribotypes through indirect (exploitative) competition.

Clostridium difficile infection: New insights into therapeutic options

Clostridium difficile infection (CDI) is an important cause of mortality and morbidity in healthcare settings and represents a major social and economic burden. The major virulence determinants are large clostridial toxins, toxin A (TcdA) and toxin B (TcdB), encoded within the pathogenicity locus. Traditional therapies, such as metronidazole and vancomycin, frequently lead to a vicious circle of recurrences due to their action against normal human microbiome. New disease management strategies together with the development of novel therapeutic and containment approaches are needed in order to better control outbreaks and treat patients. This article provides an overview of currently available CDI treatment options and discusses the most promising therapies under development.

Binaphthyl-1,2,3-triazole peptidomimetics with activity against Clostridium difficile and other pathogenic bacteria

Designed binaphthyl-based, cationic peptidomimetic antimicrobials targeting C. difficile, incorporating a click-derived 1,2,3-triazole ester isostere at the C-terminus MICs of 4 μg mL⁻¹ against three human isolates of C. difficile.

Fecal microbiota transplantation for gastrointestinal diseases

Fecal microbiota transplantation (FMT) is a treatment to restore the normal microbial composition of the gut by introducing fecal microbiota obtained from a healthy donor into a diseased individual. There has been a growing interest in the use of FMT as a treatment of various diseases including Clostridium difficile infection (CDI), inflammatory bowel disease, and irritable bowel syndrome. Despite the increasing application of FMT, there are no standard protocols. Many aspects of FMT procedures vary regarding donor selection, preparation of fecal materials, recipient preparation, and route of administration. FMT is most successful in treating recurrent CDI. A randomized controlled trial reported a success rate of approximaetly 90%. Ulcerative colitis (UC) is a potentially good indication for FMT, although limited evidence is available on the use of FMT for the treatment of UC. Only several small case series have been reported, and the results in terms of efficacy are inconsistent. FMT can also be used to treat diseases other than gastrointestinal disorders in which the gut microbiota is disturbed, e.g., cardiovascular diseases, autoimmune diseases, and metabolic disorders. There remain many unanswered questions with regard to FMT, and more research is required in this field.

Efficacy and safety of, and patient satisfaction with, colonoscopic-administered fecal microbiota transplantation in relapsing and refractory community- and hospital-acquired Clostridium difficile infection

OBJECTIVE

To report the efficacy and safety of, and patient satisfaction with, colonoscopic fecal microbiota transplantation (FMT) for community- and hospital-acquired Clostridium difficile infection (CDI).

METHODS

A retrospective medical records review of patients who underwent FMT between July 1, 2012 and August 31, 2013 was conducted. A total of 22 FMTs were performed on 20 patients via colonoscopy. The patients were divided into 'community-acquired' and 'hospital-acquired' CDI. Telephone surveys were conducted to determine procedure outcome and patient satisfaction. Primary cure rate was defined as resolution of diarrhea without recurrence within three months of FMT, whereas secondary cure rate described patients who experienced resolution of diarrhea and return of normal bowel function after a second course of FMT.

RESULTS

Nine patients met the criteria for community-acquired CDI whereas 11 were categorized as hospital-acquired CDI. A female predominance in the community-acquired group (88.89% [eight of nine]) was found (P=0.048). The primary cure rate was 100% (nine of nine) and 81.8% (nine of 11 patients) in community- and hospital-acquired CDI groups, respectively (P=0.189). Two patients in the hospital-acquired group had to undergo a repeat FMT for persistent symptomatic infection; the secondary cure rate was 100%. During the six-month follow-up, all patients were extremely satisfied with the procedure and no complications or adverse events were reported.

CONCLUSION

FMT was a highly successful and very acceptable treatment modality for treating both community- and hospital-acquired CDI.

Lactobacillus rhamnosus L34 and Lactobacillus casei L39 suppress Clostridium difficile-induced IL-8 production by colonic epithelial cells

Background

Clostridium difficile is the main cause of hospital-acquired diarrhea and colitis known as C. difficile-associated disease (CDAD).With increased severity and failure of treatment in CDAD, new approaches for prevention and treatment, such as the use of probiotics, are needed. Since the pathogenesis of CDAD involves an inflammatory response with a massive influx of neutrophils recruited by interleukin (IL)-8, this study aimed to investigate the probiotic effects of Lactobacillus spp. on the suppression of IL-8 production in response to C. difficile infection.

Results

We screened Lactobacillus conditioned media from 34 infant fecal isolates for the ability to suppress C. difficile-induced IL-8 production from HT-29 cells. Factors produced by two vancomycin-resistant lactobacilli, L. rhamnosus L34 (LR-L34) and L.casei L39 (LC-L39), suppressed the secretion and transcription of IL-8 without inhibiting C. difficile viability or toxin production. Conditioned media from LR-L34 suppressed the activation of phospho-NF-κB with no effect on phospho-c-Jun. However, LC-L39 conditioned media suppressed the activation of both phospho-NF-κB and phospho-c-Jun. Conditioned media from LR-L34 and LC-L39 also decreased the production of C. difficile-induced GM-CSF in HT-29 cells. Immunomodulatory factors present in the conditioned media of both LR-L34 and LC-L39 are heat-stable up to 100°C and > 100 kDa in size.

Conclusions

Our results suggest that L. rhamnosus L34 and L. casei L39 each produce factors capable of modulating inflammation stimulated by C. difficile. These vancomycin-resistant Lactobacillus strains are potential probiotics for treating or preventing CDAD.

Assessing control bundles for Clostridium difficile: a review and mathematical model

Clostridium difficile is the leading cause of infectious diarrhea in hospitalized patients. Integrating several infection control and prevention methods is a burgeoning strategy for reducing disease incidence in healthcare settings. We present an up-to-date review of the literature on ‘control bundles' used to mitigate the transmission of this pathogen. All clinical studies of control bundles reported substantial reductions in disease rates, in the order of 33%–61%. Using a biologically realistic mathematical model we then simulated the efficacy of different combinations of the most prominent control methods: stricter antimicrobial stewardship; the administering of probiotics/intestinal microbiota transplantation; and improved hygiene and sanitation. We also assessed the health gains that can be expected from reducing the average length of stay of inpatients. In terms of reducing the rates of colonization, all combinations had the potential to give rise to marked improvements. For example, halving the number of inpatients on broad-spectrum antimicrobials combined with prescribing probiotics or intestinal microbiota transplantation could cut pathogen carriage by two-thirds. However, in terms of symptomatic disease incidence reduction, antimicrobials, probiotics and intestinal microbiota transplantation proved substantially less effective. Eliminating within-ward transmission by improving sanitation and reducing average length of stay (from six to three days) yielded the most potent symptomatic infection control combination, cutting rates down from three to less than one per 1000 hospital bed days. Both the empirical and theoretical exploration of C. difficile control combinations presented in the current study highlights the potential gains that can be achieved through strategically integrated infection control.

Antibiotics for Treatment of Clostridium difficile Infection in Hospitalized Patients with Inflammatory Bowel Disease

Patients with inflammatory bowel disease (IBD), namely ulcerative colitis (UC) and Crohn's disease (CD), have worse outcomes with Clostridium difficile infection (CDI), including increased readmissions, colectomy, and death. Oral vancomycin is recommended for the treatment of severe CDI, while metronidazole is the standard of care for nonsevere infection. We aimed to assess treatment outcomes of CDI in IBD. We conducted a retrospective observational study of inpatients with CDI and IBD from January 2006 through December 2010. CDI severity was assessed using published criteria. Outcomes included readmission for CDI within 30 days and 12 weeks, length of stay, colectomy, and death. A total of 114 patients met inclusion criteria (UC, 62; CD, 52). Thirty-day readmissions were more common among UC than CD patients (24.2% versus 9.6%; P=0.04). Same-admission colectomy occurred in 27.4% of UC patients and 0% of CD patients (P<0.01). Severe CDI was more common among UC than CD patients (32.2% versus 19.4%; P=0.12) but not statistically significant. Two patients died from CDI-associated complications (UC, 1; CD, 1). Patients with UC and nonsevere CDI had fewer readmissions and shorter lengths of stay when treated with a vancomycin-containing regimen compared to those treated with metronidazole (30-day readmissions, 31.0% versus 0% [P=0.04]; length of stay, 13.62 days versus 6.38 days [P=0.02]). Patients with UC and nonsevere CDI have fewer readmissions and shorter lengths of stay when treated with a vancomycin-containing regimen relative to those treated with metronidazole alone. Patients with ulcerative colitis and CDI should be treated with vancomycin.

Proteomic analysis of a NAP1 Clostridium difficile clinical isolate resistant to metronidazole

BACKGROUND

Clostridium difficile is an anaerobic, Gram-positive bacterium that has been implicated as the leading cause of antibiotic-associated diarrhea. Metronidazole is currently the first-line treatment for mild to moderate C. difficile infections. Our laboratory isolated a strain of C. difficile with a stable resistance phenotype to metronidazole. A shotgun proteomics approach was used to compare differences in the proteomes of metronidazole-resistant and -susceptible isolates.

METHODOLOGY/PRINCIPAL FINDINGS

NAP1 C. difficile strains CD26A54_R (Met-resistant), CD26A54_S (reduced- susceptibility), and VLOO13 (Met-susceptible) were grown to mid-log phase, and spiked with metronidazole at concentrations 2 doubling dilutions below the MIC. Peptides from each sample were labeled with iTRAQ and subjected to 2D-LC-MS/MS analysis. In the absence of metronidazole, higher expression was observed of some proteins in C. difficile strains CD26A54_S and CD26A54_R that may be involved with reduced susceptibility or resistance to metronidazole, including DNA repair proteins, putative nitroreductases, and the ferric uptake regulator (Fur). After treatment with metronidazole, moderate increases were seen in the expression of stress-related proteins in all strains. A moderate increase was also observed in the expression of the DNA repair protein RecA in CD26A54_R.

CONCLUSIONS/SIGNIFICANCE

This study provided an in-depth proteomic analysis of a stable, metronidazole-resistant C. difficile isolate. The results suggested that a multi-factorial response may be associated with high level metronidazole-resistance in C. difficile, including the possible roles of altered iron metabolism and/or DNA repair.

Overview of Clostridium difficile infection: implications for China

The incidence and severity of Clostridium difficile infection (CDI) have dramatically increased in the Western world in recent years. In contrast, CDI is rarely reported in China, possibly due to under-diagnosis. This article briefly summarizes CDI incidence, management and preventive strategies. The authors intend to raise awareness of this disease among Chinese physicians and health workers, in order to minimize the medical and economic burden of a potential epidemic in the future.

Functional analysis of SleC from Clostridium difficile: an essential lytic transglycosylase involved in spore germination

Clostridium difficile is the most common cause of enteric disease and presents a major burden on healthcare systems globally due in part to the observed rapid rise in antibiotic resistance. The ability of C. difficile to form endospores is a key feature in the organism's pathogenesis and transmission, and contributes greatly to its resilient nature. Endospores are highly resistant to disinfection, allowing them to persist on hospital surfaces. In order for the organism to cause disease, the spores must germinate and revert to a vegetative form. While spore germination in Bacillus spp. is well understood, very little is known about this process in Clostridia. Here we report the characterization of SleC (CD0551) from C. difficile 630. Bioinformatic analysis of SleC indicated a multi-domained protein possessing a peptidoglycan-binding (PGB) domain, a SpoIID/LytB domain and an undefined N-terminal region. We have confirmed that SleC is an exo-acting lytic transglycosylase with the catalytic activity localized to the N-terminal region. Additionally, we have shown that both the N-terminal catalytic domain and the C-terminal PGB domain require muramyl-δ-lactam for substrate binding. As with carbohydrate-binding modules from cellulases and xylanases, the PGB domain may be responsible for increasing the processivity of SleC by concentrating the enzyme at the surface of the substrate.

The antimicrobial peptide cathelicidin modulates Clostridium difficile-associated colitis and toxin A-mediated enteritis in mice

BACKGROUND

Clostridium difficile mediates intestinal inflammation by releasing toxin A (TxA), a potent enterotoxin. Cathelicidins (Camp as gene name, LL-37 peptide in humans and mCRAMP peptide in mice) are antibacterial peptides that also posses anti-inflammatory properties.

OBJECTIVES

To determine the role of cathelicidins in models of Clostridium difficile infection and TxA-mediated ileal inflammation and cultured human primary monocytes.

DESIGN

Wild-type (WT) and mCRAMP-deficient (Camp(-/-)) mice were treated with an antibiotic mixture and infected orally with C difficile. Some mice were intracolonically given mCRAMP daily for 3 days. Ileal loops were also prepared in WT mice and treated with either saline or TxA and incubated for 4 h, while some TxA-treated loops were injected with mCRAMP.

RESULTS

Intracolonic mCRAMP administration to C difficile-infected WT mice showed significantly reduced colonic histology damage, apoptosis, tissue myeloperoxidase (MPO) and tumour necrosis factor (TNF)α levels. Ileal mCRAMP treatment also significantly reduced histology damage, tissue apoptosis, MPO and TNFα levels in TxA-exposed ileal loops. WT and Camp(-/-) mice exhibited similar intestinal responses in both models, implying that C difficile/TxA-induced endogenous cathelicidin may be insufficient to modulate C difficile/TxA-mediated intestinal inflammation. Both LL-37 and mCRAMP also significantly reduced TxA-induced TNFα secretion via inhibition of NF-κB phosphorylation. Endogenous cathelicidin failed to control C difficile and/or toxin A-mediated inflammation and even intestinal cathelicidin expression was increased in humans and mice.

CONCLUSION

Exogenous cathelicidin modulates C difficile colitis by inhibiting TxA-associated intestinal inflammation. Cathelicidin administration may be a new anti-inflammatory treatment for C difficile toxin-associated disease.

Clostridium difficile infection in patients with inflammatory bowel disease: An update

Inflammatory bowel disease (IBD) has many etiological factors, among which microbial factors have attracted more and more attention recently. Studies have demonstrated that the incidence of Clostridium difficile infection (CDI) in both adult and children IBD patients has been rising in recent years. Many drugs such as antibiotics, immunosuppressive agents, and acid-suppressing agents may increase the incidence of CDI. Identifying CDI and selecting effective antibiotics are keys to successful treatment, and immunological and ecological treatments are also useful choices. In this article, we will review the progress in research of CDI in IBD patients.

Clostridium difficile exposure as an insidious source of infection in healthcare settings: an epidemiological model

BACKGROUND

Clostridium difficile is the leading cause of infectious diarrhea in hospitalized patients. Its epidemiology has shifted in recent years from almost exclusively infecting elderly patients in whom the gut microbiota has been disturbed by antimicrobials, to now also infecting individuals of all age groups with no recent antimicrobial use.

METHODS

A stochastic mathematical model was constructed to simulate the modern epidemiology of C. difficile in a healthcare setting, and, to compare the efficacies of interventions.

RESULTS

Both the rate of colonization and the incidence of symptomatic disease in hospital inpatients were insensitive to antimicrobial stewardship and to the prescription of probiotics to expedite healthy gut microbiota recovery, suggesting these to be ineffective interventions to limit transmission. Comparatively, improving hygiene and sanitation and reducing average length of stay more effectively reduced infection rates. Although the majority of new colonization events are a result of within-hospital ward exposure, simulations demonstrate the importance of imported cases with new admissions.

CONCLUSIONS

By analyzing a wide range of screening sensitivities, we identify a previously ignored source of pathogen importation: although capturing all asymptomatic as well as symptomatic introductions, individuals who are exposed but not yet colonized will be missed by even a perfectly sensitive screen on admission. Empirical studies to measure the duration of this latent period of infection will be critical to assessing C. difficile control strategies. Moreover, identifying the extent to which the exposed category of individual contributes to pathogen importation should be explicitly considered for all infections relevant to healthcare settings.

Probiotics for the treatment of Clostridium difficile associated disease

The purpose of this review paper is to update the current and potential future role of probiotics for Clostridium difficile-associated disease (CDAD). Included in this review, is an update on the testing of newer probiotics (e.g., Bacillus coagulans GBI-30, 6086) in animal models of CDAD. There is a focus on the modulation of signal transduction pathways (i.e., transcription factors like cAMP response element-binding, activator protein 1, and nuclear factor kappa B), as well as the inhibition of certain kinases (e.g., p38 mitogen activated protein kinases) by probiotics. Inhibition of signal transduction by probiotics, such as Saccharomyces boulardii, result in multiple effects on intestinal fluid secretion, neutrophil influx into the colon, inflammation, and colonocyte apoptosis that may positively impact CDAD. Recent clinical approaches with probiotics, for the prevention of primary and recurrent CDAD, are also summarized in this review paper. Future directions for the treatment of CDAD by probiotics are also mentioned in this review. In particular, the use of multi-strain probiotic formulations such as Ecologic^® AAD and VSL #3^® may represent a rationale pharmacological approach, particularly as adjunctive therapies for CDAD. Understanding the mechanistic basis of CDAD, and how probiotics interfere at ceratin steps in the pathogenic process, may also present the opportunity to design other multi-strain probiotics that could have a future impact on CDAD.

Elevated lactoferrin is associated with moderate to severe Clostridium difficile disease, stool toxin, and 027 infection

We evaluated blood and fecal biomarkers as indicators of severity in symptomatic patients with confirmed Clostridium difficile infection (CDI). Recruitment included patients with CDI based on clinical symptoms and supporting laboratory findings. Disease severity was defined by physician’s assessment and blood and fecal biomarkers were measured. Toxigenic culture done using spore enrichment and toxin B detected by tissue culture were done as confirmatory tests. Polymerase chain reaction (PCR) ribotyping was performed on each isolate. There were 98 patients recruited, with 85 (87 %) confirmed cases of toxigenic CDI (21 severe, 57 moderate, and seven mild), of which 68 (80 %) were also stool toxin-positive. Elevated lactoferrin (p = 0.01), increased white blood cell (WBC) count (p = 0.08), and low serum albumin (p = 0.03) were all associated with the more severe cases of CDI. Ribotype 027 infection accounted for 71 % of severe cases (p < 0.01) and patients with stool toxin had significantly higher lactoferrin levels and WBC counts (p < 0.05). Our findings show that elevated fecal lactoferrin, along with increased WBC count and low serum albumin, were associated with more severe CDI. In addition, patients infected with ribotype 027 and those with stool toxin had significantly higher fecal lactoferrin and WBC counts.

The impact of pseudomembrane formation on the outcome of Clostridium difficile-associated disease

PURPOSE

Although pseudomembranes are the hallmark manifestation of Clostridium difficile-associated diarrhea (CDAD), there are scant data specifically addressing their impact on the clinical outcome. We investigated whether the formation of pseudomembranes predicts a worse CDAD outcome.

METHODS

CDAD patients hospitalized during 2010 underwent sigmoidoscopy and were followed prospectively. In addition, all hospitalized CDAD patients in the period 01/2000-12/2009 who underwent lower endoscopy were retrospectively identified and their charts reviewed. Patients with detectable pseudomembranes on endoscopy were compared to those in whom pseudomembranes were absent. Thirty-day mortality and a composite outcome comprised of mortality within 30 days of diagnosis, admission to the intensive care unit (ICU), colectomy, peritonitis, hemodynamic instability, or respiratory insufficiency were addressed. Additional clinical outcomes used for comparison between the two groups were 60-day mortality, duration of hospitalization, and the failure of metronidazole and vancomycin.

RESULTS

A total of 117 CDAD patients (mean age 62.9 ± 19 years) who underwent lower endoscopy were included; 46 with pseudomembranes and 71 without. Seven out of the 46 patients with pseudomembranes died within 30 days compared to 9/71 in the non-pseudomembrane group [odds ratio (OR) 1.2, 95% confidence interval (CI) 0.4-3.6, P = 0.8]. Similarly, there was no correlation between the occurrence of pseudomembranes and the rate of the composite adverse outcome (P = 0.6). In contrast, acute renal insufficiency (OR 15, 95% CI 3.2-72, P < 0.001) and hypoalbuminemia (OR 5.7, 95% CI 1.8-18, P = 0.002) were both independently predictive of a severe clinical outcome.

CONCLUSIONS

Our findings suggest that the presence of pseudomembranes is not associated with an adverse outcome in CDAD patients.

Factors associated with the use of probiotics in patients with inflammatory bowel disease

Background: Probiotic preparations are heavily promoted in the United Kingdom and are widely available to purchase. Probiotics have multiple effects on gastrointestinal functions and may have beneficial or even harmful effects in inflammatory bowel disease (IBD). Various complementary and alternative medicines are commonly used by IBD patients but there is much less data specifically on the use of probiotics. 

Aim: To examine the current use of probiotics by IBD patients and determine the factors associated with probiotic use.

Methods: Subjects with IBD undergoing routine care at a UK teaching hospital underwent a standardized structured questionnaire-interview. Current use of probiotics was explored and patient- and disease-related factors examined. IBD-related quality of life was assessed with the short inflammatory bowel disease questionnaire (S-IBDQ). Logistical regression was used to explore factors associated with probiotic use.

Results: Forty subjects were interviewed.  Probiotic use was common, 40% of subjects being regular users. Probiotic use was significantly associated with a shorter duration of IBD since diagnosis, a diagnosis of Crohn’s disease, formal post-18 education and lower quality of life as assessed by the S-IBDQ. A preference for the taste of the preparation was as common a reason for using probiotics as were potential disease modifying effects. Non-users reported that the costs of the preparations and doubts about efficacy were the primary reasons for non-use.

Conclusions: In this study probiotic use was common in IBD patients. Several patient- and disease- related factors, including a lower perceived quality of life, were associated with the use of probiotics.