Treatment failure and recurrence of Clostridium difficile infection following treatment with vancomycin or metronidazole: a systematic review of the evidence

Extracellular DNA, cell surface proteins and c-di-GMP promote biofilm formation in Clostridioides difficile

Clostridioides difficile is the leading cause of nosocomial antibiotic-associated diarrhoea worldwide, yet there is little insight into intestinal tract colonisation and relapse. In many bacterial species, the secondary messenger cyclic-di-GMP mediates switching between planktonic phase, sessile growth and biofilm formation. We demonstrate that c-di-GMP promotes early biofilm formation in C. difficile and that four cell surface proteins contribute to biofilm formation, including two c-di-GMP regulated; CD2831 and CD3246, and two c-di-GMP-independent; CD3392 and CD0183. We demonstrate that C. difficile biofilms are composed of extracellular DNA (eDNA), cell surface and intracellular proteins, which form a protective matrix around C. difficile vegetative cells and spores, as shown by a protective effect against the antibiotic vancomycin. We demonstrate a positive correlation between biofilm biomass, sporulation frequency and eDNA abundance in all five C. difficile lineages. Strains 630 (RT012), CD305 (RT023) and M120 (RT078) contain significantly more eDNA in their biofilm matrix than strains R20291 (RT027) and M68 (RT017). DNase has a profound effect on biofilm integrity, resulting in complete disassembly of the biofilm matrix, inhibition of biofilm formation and reduced spore germination. The addition of exogenous DNase could be exploited in treatment of C. difficile infection and relapse, to improve antibiotic efficacy.

Safety and Efficacy of Fidaxomicin and Vancomycin in Children and Adolescents with Clostridioides (Clostridium) difficile Infection: A Phase 3, Multicenter, Randomized, Single-blind Clinical Trial (SUNSHINE)

BACKGROUND

Fidaxomicin, a narrow-spectrum antibiotic approved for Clostridioides (Clostridium) difficile infection (CDI) in adults, is associated with lower rates of recurrence than vancomycin; however, pediatric data are limited. This multicenter, investigator-blind, phase 3, parallel-group trial assessed the safety and efficacy of fidaxomicin in children.

METHODS

Patients aged <18 years with confirmed CDI were randomized 2:1 to 10 days of treatment with fidaxomicin (suspension or tablets, twice daily) or vancomycin (suspension or tablets, 4 times daily). Safety assessments included treatment-emergent adverse events. The primary efficacy end point was confirmed clinical response (CCR), 2 days after the end of treatment (EOT). Secondary end points included global cure (GC; CCR without CDI recurrence) 30 days after EOT (end of study; EOS). Plasma and stool concentrations of fidaxomicin and its active metabolite OP-1118 were measured.

RESULTS

Of 148 patients randomized, 142 were treated (30 <2 years old). The proportion of participants with treatment-emergent adverse events was similar with fidaxomicin (73.5%) and vancomycin (75.0%). Of 3 deaths in the fidaxomicin arm during the study, none were CDI or treatment related. The rate of CCR at 2 days after EOT was 77.6% (76 of 98 patients) with fidaxomicin and 70.5% (31 of 44) with vancomycin, whereas the rate of GC at EOS was significantly higher in participants receiving fidaxomicin (68.4% vs 50.0%; adjusted treatment difference, 18.8%; 95% confidence interval, 1.5%-35.3%). Systemic absorption of fidaxomicin and OP-1118 was minimal, and stool concentrations were high.

CONCLUSIONS

Compared with vancomycin, fidaxomicin was well tolerated and demonstrated significantly higher rates of GC in children and adolescents with CDI.

CLINICAL TRIALS REGISTRATION

NCT02218372.

Repurposing the Veterinary Antiprotozoal Drug Ronidazole for the Treatment of Clostridioides difficile Infection

Clostridioides difficile infection (CDI) is a principal cause of hospital-acquired infections and fatalities worldwide. The need for new, more potent anticlostridial agents is far from being met. Drug repurposing can be utilized as a rapid and cost-efficient method of drug development. The current study was conducted to evaluate the activity of ronidazole, a veterinary antiprotozoal drug, as a potential treatment for CDI. Ronidazole inhibited the growth of clinical C. difficile isolates (including NAP1 and toxigenic strains) at a very low concentration (0.125 µg/mL) and showed superior killing kinetics compared with metronidazole, an anticlostridial agent from the same chemical category. In addition, ronidazole did not inhibit growth of several commensal organisms naturally present in the human intestine that play a protective role in preventing CDIs. Furthermore, ronidazole was found to be non-toxic to human gut cells and permeated a monolayer of colonic epithelial cells (Caco-2) at a slower rate than metronidazole. Finally, ronidazole outperformed metronidazole when both were tested at a dose of 1 mg/kg daily in a mouse model of CDI. Overall, ronidazole merits further investigation as a potential treatment for CDIs.

Ultrapotent Inhibitor of Clostridioides difficile Growth, Which Suppresses Recurrence In Vivo

Clostridioides difficile is the leading cause of healthcare-associated infection in the U.S. and considered an urgent threat by the Centers for Disease Control and Prevention (CDC). Only two antibiotics, vancomycin and fidaxomicin, are FDA-approved for the treatment of C. difficile infection (CDI), but these therapies still suffer from high treatment failure and recurrence. Therefore, new chemical entities to treat CDI are needed. Trifluoromethylthio-containing N-(1,3,4-oxadiazol-2-yl)benzamides displayed very potent activities [sub-μg/mL minimum inhibitory concentration (MIC) values] against Gram-positive bacteria. Here, we report remarkable antibacterial activity enhancement via halogen substitutions, which afforded new anti-C. difficile agents with ultrapotent activities [MICs as low as 0.003 μg/mL (0.007 μM)] that surpassed the activity of vancomycin against C. difficile clinical isolates. The most promising compound in the series, HSGN-218, is nontoxic to mammalian colon cells and is gut-restrictive. In addition, HSGN-218 protected mice from CDI recurrence. Not only does this work provide a potential clinical lead for the development of C. difficile therapeutics but also highlights dramatic drug potency enhancement via halogen substitution.

Effect of nitazoxanide on diarrhea: A systematic review and network meta-analysis of randomized controlled trials

We aimed to systematically review evidence pertaining to the safety and efficacy of nitazoxanide in treating infectious diarrhea. On September 21, 2017, we identified relevant studies using 12 databases. The estimates of the included studies were pooled as a risk ratio (RR). We conducted a network and pairwise random-effects meta-analysis for both direct and indirect comparisons of different organisms that are known to cause diarrhea. The primary and secondary analysis outcomes were clinical response until cessation of illness, parasitological response and adverse events. We included 18 studies in our analysis. In cryptosporidiosis, the overall estimate favored nitazoxanide in its clinical response in comparison with placebo RR 1.46 [95% CI 1.22-1.74; P-value <0.0001]. Network meta-analysis among patients with Giardia intestinalis showed an increase in the probability of diarrheal cessation and parasitological responses in comparison with placebo, RR 1.69 [95% CI 1.08-2.64, P-score 0.27] and RR 2.91 [95% CI 1.72-4.91, P-score 0.55] respectively. In Clostridium difficile infection, the network meta-analysis revealed a non-significantly superior clinical response effect of nitazoxanide to metronidazole 31 days after treatment RR 1.21 [95% CI 0.87-1.69, P-score 0.26]. In Entamoeba histolytica, the overall estimate significantly favored nitazoxanide in parasitological response with placebo RR 1.80 [95% CI 1.35-2.40, P-value < 0.001]. We highlighted the effectiveness of nitazoxanide in the cessation of diarrhea caused by Cryptosporidium, Giardia intestinalis and Entamoeba histolytica infection. We also found significant superiority of NTZ to metronidazole in improving the clinical response to G. intestinalis, thus it may be a suitable candidate for treating infection-induced diarrhea. To prove the superiority of NTZ during a C. difficile infection may warrant a larger-scale clinical trial since its superiority was deemed insignificant. We recommend nitazoxanide as an appropriate option for treating infectious diarrhea.

Fecal Microbiota Transplant: Latest Addition to Arsenal Against Recurrent Clostridium Difficile Infection

An infectious disease of colon, recurrent Clostridium difficile infection (RCDI) is hitherto considered insurmountable leading to significant morbidity and mortality. Gut dysbiosis, generally resulting from frequent use of antibiotics is considered to be responsible for the etiopathogenesis of rCDI. Ironically, the conventional treatment strategies for the disease also include the use of anti-infective drugs such as metronidazole, vancomycin and fidaxomycin. As a result of the efforts to overcome the limitations of these treatment options to control recurrence of disease, Fecal Microbiota Transplant (FMT) has emerged as an effective and safe alternative. It is pertinent to add here that FMT is defined as the process of engraftment of fecal suspension from the healthy person into the gastrointestinal tract of the diseased individual aiming at the restoration of gut microbiota. FMT has proved to be quite successful in the treatment of recurrent and resistant Clostridium difficile infections (RCDI). In last three decades a lot of information has been generated on the use of FMT for RCDI. A number of clinical trials have been reported with generally very high success rates. However, very small number of patents could be found in the area indicating that there still exists lacuna in the knowledge about FMT with respect to its preparation, regulation, mode of delivery and safety. The current review attempts to dive deeper to discuss the patents available in the area while supporting the information contained therein with the non-patent literature.

What Is the Role for Metronidazole in the Treatment of Clostridium difficile Infection? Results From a National Cohort Study of Veterans With Initial Mild Disease

BACKGROUND

Metronidazole may still be an appropriate therapeutic option for mild Clostridium difficile infection (CDI) in select patients, but data are limited to guide clinicians in identifying these patients.

METHODS

Our 2-stage study included a national cohort of Veterans with a first episode of mild CDI (2010-2014). First, among those treated with metronidazole, we identified predictors of success, defined as absence of all-cause mortality or recurrence 30 days posttreatment, using multivariable unconditional logistic regression. Second, among a subgroup of patients with characteristics predictive of success identified in the first stage, we compared clinical outcomes among those treated with metronidazole compared with vancomycin, using Cox proportional hazards models for time to 30-day all-cause mortality, CDI recurrence, and failure.

RESULTS

Among 3656 patients treated with metronidazole, we identified 3282 patients with success and 374 patients without success (failure). Younger age was the only independent predictor of success. Age ≤65 years was associated with an odds of success 1.63 times higher (95% confidence interval [CI], 1.29-2.06) than age >65 years. Among 115 propensity score-matched pairs ≤65 years of age, no significant differences were observed between metronidazole and vancomycin (reference) for all-cause mortality (hazard ratio [HR], 0.29 [95% CI, .06-1.38]), CDI recurrence (HR, 0.62 [95% CI, .26-1.49]), or failure (HR, 0.50 [95% CI, .23-1.07]).

CONCLUSIONS

Among patients ≤65 years of age with initial mild CDI, clinical outcomes were similar with metronidazole and vancomycin. These data suggest that metronidazole may be considered for the treatment of initial mild CDI among patients 65 years of age or younger.

Discovery of a Potent Picolinamide Antibacterial Active against Clostridioides difficile

A major challenge for chemotherapy of bacterial infections is perturbation of the intestinal microbiota. Clostridioides difficile is a Gram-positive bacterium of the gut that can thrive under this circumstance. Its production of dormant and antibiotic-impervious spores results in chronic disruption of normal gut flora and debilitating diarrhea and intestinal infection. C. difficile is responsible for 12,800 deaths per year in the United States. Here, we report the discovery of 2-(4-(3-(trifluoromethoxy)phenoxy)picolinamido)benzo[d]oxazole-5-carboxylate as an antibacterial with potent and selective activity against C. difficile. Its MIC₅₀ and MIC₉₀ (the concentration required to inhibit the growth of 50% and 90% of all the tested strains, respectively) values, documented across 101 strains of C. difficile, are 0.12 and 0.25 μg/mL, respectively. The compound targets cell wall biosynthesis, as assessed by macromolecular biosynthesis assays and by scanning electron microscopy. Animals infected with a lethal dose of C. difficile and treated with compound 1 had a similar survival compared to treatment with vancomycin, which is the frontline antibiotic used for C. difficile infection.

The (p)ppGpp Synthetase RSH Mediates Stationary-Phase Onset and Antibiotic Stress Survival in Clostridioides difficile

The human pathogen Clostridioides difficile is increasingly tolerant of multiple antibiotics and causes infections with a high rate of recurrence, creating an urgent need for new preventative and therapeutic strategies. The stringent response, a universal bacterial response to extracellular stress, governs antibiotic survival and pathogenesis in diverse organisms but has not previously been characterized in C. difficile Here, we report that the C. difficile (p)ppGpp synthetase RSH is incapable of utilizing GTP or GMP as a substrate but readily synthesizes ppGpp from GDP. The enzyme also utilizes many structurally diverse metal cofactors for reaction catalysis and remains functionally stable at a wide range of environmental pHs. Transcription of rsh is stimulated by stationary-phase onset and by exposure to the antibiotics clindamycin and metronidazole. Chemical inhibition of RSH by the ppGpp analog relacin increases antibiotic susceptibility in epidemic C. difficile R20291, indicating that RSH inhibitors may be a viable strategy for drug development against C. difficile infection. Finally, transcriptional suppression of rsh also increases bacterial antibiotic susceptibility, suggesting that RSH contributes to C. difficile antibiotic tolerance and survival.IMPORTANCE Clostridioides difficile infection (CDI) is an urgent public health threat with a high recurrence rate, in part because the causative bacterium has a high rate of antibiotic survival. The (p)ppGpp-mediated bacterial stringent response plays a role in antibiotic tolerance in diverse pathogens and is a potential target for development of new antimicrobials because the enzymes that metabolize (p)ppGpp have no mammalian homologs. We report that stationary-phase onset and antibiotics induce expression of the clostridial ppGpp synthetase RSH and that both chemical inhibition and translational suppression of RSH increase C. difficile antibiotic susceptibility. This demonstrates that development of RSH inhibitors to serve as adjuvants to antibiotic therapy is a potential approach for the development of new strategies to combat CDI.

Clostridioides difficile para-Cresol Production Is Induced by the Precursor para-Hydroxyphenylacetate

Clostridioides difficile is an etiological agent for antibiotic-associated diarrheal disease. C. difficile produces a phenolic compound, para-cresol, which selectively targets gammaproteobacteria in the gut, facilitating dysbiosis. C. difficile decarboxylates para-hydroxyphenylacetate (p-HPA) to produce p-cresol by the action of the HpdBCA decarboxylase encoded by the hpdBCA operon. Here, we investigate regulation of the hpdBCA operon and directly compare three independent reporter systems; SNAP-tag, glucuronidase gusA, and alkaline phosphatase phoZ reporters to detect basal and inducible expression. We show that expression of hpdBCA is upregulated in response to elevated p-HPA. In silico analysis identified three putative promoters upstream of hpdBCA operon-P₁, P₂, and Pσ⁵⁴; only the P₁ promoter was responsible for both basal and p-HPA-inducible expression of hpdBCA We demonstrated that turnover of tyrosine, a precursor for p-HPA, is insufficient to induce expression of the hpdBCA operon above basal levels because it is inefficiently converted to p-HPA in minimal media. We show that induction of the hpdBCA operon in response to p-HPA occurs in a dose-dependent manner. We also identified an inverted palindromic repeat (AAAAAG-N₁₃-CTTTTT) upstream of the hpdBCA start codon (ATG) that is essential for inducing transcription of the hpdBCA operon in response to p-HPA, which drives the production of p-cresol. This provides insights into the regulatory control of p-cresol production, which affords a competitive advantage for C. difficile over other intestinal bacteria, promoting dysbiosis.IMPORTANCE Clostridioides difficile infection results from antibiotic-associated dysbiosis. para-Cresol, a phenolic compound produced by C. difficile, selectively targets gammaproteobacteria in the gut, facilitating dysbiosis. Here, we demonstrate that expression of the hpdBCA operon, encoding the HpdBCA decarboxylase which converts p-HPA to p-cresol, is upregulated in response to elevated exogenous p-HPA, with induction occurring between >0.1 and ≤0.25 mg/ml. We determined a single promoter and an inverted palindromic repeat responsible for basal and p-HPA-inducible hpdBCA expression. We identified turnover of tyrosine, a p-HPA precursor, does not induce hpdBCA expression above basal level, indicating that exogenous p-HPA was required for p-cresol production. Identifying regulatory controls of p-cresol production will provide novel therapeutic targets to prevent p-cresol production, reducing C. difficile's competitive advantage.

Fidaxomicin for the treatment of Clostridioides difficile in children

Fidaxomicin is an oral narrow-spectrum novel 18-membered macrocyclic antibiotic that was initially approved in 2011 by the US FDA for the treatment of Clostridioides difficile infections (CDI) in adults. In February 2020, the FDA approved fidaxomicin for the treatment of CDI in children age >6 months. In adults, fidaxomicin is as efficacious as vancomycin in treating CDI and reduces the risk of recurrent CDI. An investigator-blinded, randomized, multicenter, multinational clinical trial comparing the efficacy and safety of fidaxomicin with vancomycin in children was recently published confirming similar findings as previously reported in adults. Fidaxomicin is the first FDA-approved treatment for CDI in children and offers a promising option for reducing recurrent CDI in this population.

The cytotoxic synergy between Clostridioides difficile toxin B and proinflammatory cytokines: an unholy alliance favoring the onset of Clostridioides difficile infection and relapses

Clostridioides difficile infection (CDI) represents an important health problem worldwide, with significant morbidity and mortality. This infection has also high recurrence rates, whose pathophysiological grounds are still poorly understood. Based on our experiments in vitro with Clostridioides difficile toxin B and existing experimental and clinical evidence, we propose that primary CDI and relapses might be favored by a mechanism that involves the enhancement of the toxicity of toxin B by proinflammatory cytokines, tumor necrosis factor alpha, and interferon gamma on the enteric glial cells and their network in an environment characterized by a strong dysmicrobism.

An ecological framework to understand the efficacy of fecal microbiota transplantation

Human gut microbiota plays critical roles in physiology and disease. Our understanding of ecological principles that govern the dynamics and resilience of this highly complex ecosystem remains rudimentary. This knowledge gap becomes more problematic as new approaches to modifying this ecosystem, such as fecal microbiota transplantation (FMT), are being developed as therapeutic interventions. Here we present an ecological framework to understand the efficacy of FMT in treating conditions associated with a disrupted gut microbiota, using the recurrent Clostridioides difficile infection as a prototype disease. This framework predicts several key factors that determine the efficacy of FMT. Moreover, it offers an efficient algorithm for the rational design of personalized probiotic cocktails to decolonize pathogens. We analyze data from both preclinical mouse experiments and a clinical trial of FMT to validate our theoretical framework. The presented results significantly improve our understanding of the ecological principles of FMT and have a positive translational impact on the rational design of general microbiota-based therapeutics.

Here, the authors present a theoretical framework based on community ecology and network science to investigate the efficacy of fecal microbiota transplantation in conditions associated with a disrupted gut microbiota, using the recurrent Clostridioides difficile infection as a prototype disease.

[Updated review of Clostridium difficile infection in elderly]

Clostridium difficile infection is the most common cause of health care-associated diarrhoea, and its incidence increases with age. Clinical challenges, risk of resistance to treatment, risk of recurrence, and treatment responses are different in elderly. The aim of this review is to discuss the updated epidemiology, pathophysiology, diagnosis, and therapeutic management of C. difficile infection in elderly with the available data.

Repurposing the Antiamoebic Drug Diiodohydroxyquinoline for Treatment of Clostridioides difficile Infections

Clostridioides difficile, the leading cause of nosocomial infections, is an urgent health threat worldwide. The increased incidence and severity of disease, the high recurrence rates, and the dearth of effective anticlostridial drugs have created an urgent need for new therapeutic agents. In an effort to discover new drugs for the treatment of Clostridioides difficile infections (CDIs), we investigated a panel of FDA-approved antiparasitic drugs against C. difficile and identified diiodohydroxyquinoline (DIHQ), an FDA-approved oral antiamoebic drug. DIHQ exhibited potent activity against 39 C. difficile isolates, inhibiting growth of 50% and 90% of these isolates at concentrations of 0.5 μg/ml and 2 μg/ml, respectively. In a time-kill assay, DIHQ was superior to vancomycin and metronidazole, reducing a high bacterial inoculum by 3 log₁₀ within 6 h. Furthermore, DIHQ reacted synergistically with vancomycin and metronidazole against C. difficile in vitro. Moreover, at subinhibitory concentrations, DIHQ was superior to vancomycin and metronidazole in inhibiting two key virulence factors of C. difficile, toxin production and spore formation. Additionally, DIHQ did not inhibit the growth of key species that compose the host intestinal microbiota, such as Bacteroides, Bifidobacterium, and Lactobacillus spp. Collectively, our results indicate that DIHQ is a promising anticlostridial drug that warrants further investigation as a new therapeutic for CDIs.

Auranofin, at clinically achievable dose, protects mice and prevents recurrence from Clostridioides difficile infection

Clostridioides difficile is the leading cause of nosocomial infections and a worldwide urgent public health threat. Without doubt, there is an urgent need for new effective anticlostridial agents due to the increasing incidence and severity of C. difficile infection (CDI). The aim of the present study is to investigate the in vivo efficacy of auranofin (rheumatoid arthritis FDA-approved drug) in a CDI mouse model and establish an adequate dosage for treatment. The effects of increased C. difficile inoculum, and pre-exposure to simulated gastric intestinal fluid (SGF) and simulated intestinal fluid (SIF), on the antibacterial activity of auranofin were investigated. Auranofin's in vitro antibacterial activity was stable in the presence of high bacterial inoculum size compared to vancomycin and fidaxomicin. Moreover, it maintained its anti-C. difficile activity after being exposed to SGF and SIF. Upon testing in a CDI mouse model, auranofin at low clinically achievable doses (0.125 mg/kg and 0.25 mg/kg) significantly protected mice against CDI with 100% and 80% survival, respectively. Most importantly, auranofin (0.125 mg/kg and 0.25 mg/kg) significantly prevented CDI recurrence when compared with vancomycin. Collectively, these results indicate that auranofin could potentially provide an effective, safe and quick supplement to the current approaches for treating CDI.

The Route to Palatable Fecal Microbiota Transplantation

The community of symbiotic microorganisms that reside in our gastrointestinal tract is integral to human health. Fecal microbiota transplantation (FMT) has been shown to be highly effective in treating recurrent Clostridioides difficile infection (rCDI) and is now recommended by medical societies for patients suffering from rCDI who have failed to respond to conventional therapy. The main challenges with FMT are its accessibility, acceptability, lack of standardization, and regulatory complexity, which will be discussed in this review. Access to FMT is being addressed through the development of frozen and lyophilized FMT preparations that can be prepared at stool banks and shipped to the point of care. Both access and patient acceptance would be enhanced by oral FMT capsules, and there is potential to reduce capsule burden by utilizing colonic release capsules, targeting the site of disease. This review compares the efficacy of different FMT routes of administration: capsules, nasal feeding tubes, enemas, and colonoscopic infusions. FMT is considered investigational by the Food and Drug Administration. In effort to improve access to FMT, physicians may perform FMT outside of an investigational new drug application for treating CDI infections not responsive to standard therapies. The majority of FMT studies report only minor adverse effects; however, there is risk of transmission of infections.

Management of difficult-to-treat Clostridioides difficile in a patient with chronic osteomyelitis

A 61-year-old male patient being treated with intravenous antibiotics for left foot osteomyelitis presented to the hospital septic, with several days of worsening abdominal pain, bloating and watery bowel movements. Investigation revealed that the patient had severe, treatment-resistant Clostridioides difficile colitis. He was initially treated with oral vancomycin and intravenous metronidazole, which was switched to oral fidaxomicin. After no improvement in the patient's symptoms, he was treated with two faecal microbiota transplants. He was offered a third faecal microbiota transplant but declined. The patient was placed back on oral fidaxomicin and saw ultimate resolution of his symptoms. This case provides an example of a treatment pathway for refractory C. difficile infection.

Clostridioides difficile infections in the intensive care unit: a monocentric cohort study

Introduction

Patient-level data from Clostridioides difficile infections (CDI) treated in an intensive care setting is limited, despite the growing medical and financial burden of CDI.

Methods

We retrospectively analyzed data from 100 medical intensive care unit patients at the University Hospital Cologne with respect to demography, diagnostics, severity scores, treatment, and outcome. To analyze factors influencing response to treatment and death, a backward-stepwise multiple logistic regression model was applied.

Results

Patients had significant comorbidities including 26% being immunocompromised. The mean Charlson Comorbidity Index was 6.3 (10-year survival rate of 2.25%). At the time of diagnosis, the APACHE II was 17.4±6.3 (predicted mortality rate of 25%), and the ATLAS score was 5.2±1.9 (predicted cure rate of 75%). Overall, 47% of CDI cases were severe, 35% were complicated, and 23% were both. At least one concomitant antibiotic was given to 74% of patients. The cure rate after 10 and 90 days was 56% and 51%, respectively. Each unit increment in APACHE II score was associated with poorer treatment response (OR 0.931; 95% CI 0.872–0.995; p = 0.034). Age above 65 years was associated with death (OR 2.533; 95% CI 1.031–6.221; p = 0.043), and overall mortality at 90 days was 56%.

Conclusions

CDI affects a high-risk population, in whom predictive scoring tools are not accurate, and outcomes are poor despite intensive treatment. Further research in this field is warranted to improve prediction scoring and patient outcomes.

Electronic supplementary material

The online version of this article (10.1007/s15010-020-01413-8) contains supplementary material, which is available to authorized users.

The gut microbiome diversity of Clostridioides difficile-inoculated mice treated with vancomycin and fidaxomicin

OBJECTIVE

To investigate the effect of vancomycin and fidaxomicin on the diversity of intestinal microbiota in a mouse model of Clostridioides difficile infection.

METHODS

Mice were divided into 11 models (4 mice per model): 6 uninoculated models and 5 models inoculated with C. difficile BI/NAP1/027. Inoculated models were prepared using intraperitoneal clindamycin followed by inoculation with C. difficile BI/NAP1/027. Uninoculated and C. difficile-inoculated mice received 2 or 7 days' vancomycin or fidaxomicin. Clostridium butyricum MIYAIRI 588 probiotic and lactoferrin prebiotic were administered for 10 days to uninoculated mice. Intestinal microbiome composition was investigated by sequence analyses of bacterial 16S rRNA genes from faeces, and microbiota diversity estimated.

RESULTS

In uninoculated, untreated ('normal') mice, Clostridia (57.8%) and Bacteroidia (32.4%) accounted for the largest proportions of gut microbiota. The proportion of Clostridia was numerically reduced in C. difficile-inoculated versus normal mice. Administration of vancomycin to C. difficile-inoculated mice reduced the proportions of Bacteroidia and Clostridia, and increased that of Proteobacteria. Administration of fidaxomicin to C. difficile-inoculated mice reduced the proportion of Clostridia to a lesser extent, but increased that of Bacteroidia. Microbiota diversity was lower in C. difficile-inoculated versus normal mice (164.5 versus 349.1 operational taxonomic units (OTUs), respectively); treatment of C. difficile-inoculated mice with 7 days' vancomycin reduced diversity to a greater extent than did 7 days' fidaxomicin treatment (26.2 versus 134.2 OTUs, respectively).

CONCLUSIONS

Both C. difficile inoculation and treatment with vancomycin or fidaxomicin reduced microbiota diversity; however, dysbiosis associated with fidaxomicin was milder than with vancomycin.

Fecal microbiota transplantation for recurrent Clostridioides difficile infection

PURPOSE

Randomized controlled trials investigating the efficacy and safety of fecal microbiota transplantation (FMT) for recurrent Clostridioides difficile infection (CDI) are reviewed, and practical issues for pharmacists to consider are discussed.

SUMMARY

Eight randomized controlled trials evaluating the use of FMT for recurrent CDI were analyzed. The trials varied in the type of sample (fresh, frozen, lyophilized), route of administration (nasogastric tube, colonoscopy, enema, oral), and comparator agent (different type of FMT, vancomycin). Efficacy rates ranged from 43.8% to 96.2% with FMT, and safety data were relatively similar. With these favorable data, pharmacists are likely to be involved at multiple steps in the delivery of FMT to patients with recurrent CDI, including the procurement, documentation, and administration of various products and patient education.

CONCLUSION

FMT is an option for recurrent CDI that is supported by findings of randomized controlled trials, although a preferred method for the delivery remains to be defined. Pharmacists can play an important role in the successful management of patients with recurrent CDI who may benefit from FMT.

Method comparison for the direct enumeration of bacterial species using a chemostat model of the human colon

BACKGROUND

Clostridioides difficile infection (CDI) has a high recurrent infection rate. Faecal microbiota transplantation (FMT) has been used successfully to treat recurrent CDI, but much remains unknown about the human gut microbiota response to replacement therapies. In this study, antibiotic-mediated dysbiosis of gut microbiota and bacterial growth dynamics were investigated by two quantitative methods: real-time quantitative PCR (qPCR) and direct culture enumeration, in triple-stage chemostat models of the human colon. Three in vitro models were exposed to clindamycin to induce simulated CDI. All models were treated with vancomycin, and two received an FMT. Populations of total bacteria, Bacteroides spp., Lactobacillus spp., Enterococcus spp., Bifidobacterium spp., C. difficile, and Enterobacteriaceae were monitored using both methods. Total clostridia were monitored by selective culture. Using qPCR analysis, we additionally monitored populations of Prevotella spp., Clostridium coccoides group, and Clostridium leptum group.

RESULTS

Both methods showed an exacerbation of disruption of the colonic microbiota following vancomycin (and earlier clindamycin) exposure, and a quicker recovery (within 4 days) of the bacterial populations in the models that received the FMT. C. difficile proliferation, consistent with CDI, was also observed by both qPCR and culture. Pearson correlation coefficient showed an association between results varying from 98% for Bacteroides spp., to 62% for Enterobacteriaceae.

CONCLUSIONS

Generally, a good correlation was observed between qPCR and bacterial culture. Overall, the molecular assays offer results in real-time, important for treatment efficacy, and allow the monitoring of additional microbiota groups. However, individual quantification of some genera (e.g. clostridia) might not be possible without selective culture.

Microbiological Characterization and Clinical Outcomes After Extended-Pulsed Fidaxomicin Treatment for Clostridioides difficile Infection in the EXTEND Study

Background

Clostridioides (Clostridium) difficile infection (CDI) is diagnosed using clinical signs and symptoms plus positive laboratory tests. Recurrence of CDI after treatment is common, and coinfection with other enteric pathogens may influence clinical outcomes.

Methods

We aimed to assess rates of C difficile positivity, by enzyme-linked immunosorbent assay (ELISA) toxin A/B and BioFire FilmArray, and the effect of enteric coinfection on clinical outcomes, using samples from the EXTEND study of extended-pulsed fidaxomicin (EPFX) versus standard vancomycin.

Results

All 356 randomized and treated patients tested positive for C difficile toxin A/B by local tests; a majority (225 of 356, 63.2%) also tested positive by both ELISA and BioFire. Most stool samples taken at screening tested positive for C difficile only using BioFire (EPFX: 112 of 165, 69.7%; vancomycin: 118 of 162, 72.8%). Of the 5 patients who failed treatment and had stool samples available, all (1) had tested negative for C difficile by BioFire at screening and (2) were negative by ELISA at time of treatment failure. When analyzed by BioFire results at screening, rates of sustained clinical cure at 30 days after end of treatment were numerically higher with EPFX than with vancomycin for almost all patients, except for those who tested negative for C difficile but positive for another pathogen. However, these outcome differences by presence of coinfection did not reach statistical significance. Whole-genome sequencing analysis determined that 20 of 26 paired samples from patients with recurrence were reinfections with the same C difficile strain.

Conclusions

Testing for presence of copathogens in clinical trials of antibiotics could help to explain clinical failures.

Fidaxomicin compared with vancomycin and metronidazole for the treatment of Clostridioides (Clostridium) difficile infection: A network meta-analysis

We conducted a systematic review of the literature and network meta-analysis (NMA) to compare the relative effectiveness of antibiotic treatments for Clostridioides (Clostridium) difficile infection (CDI) including vancomycin (VCM), metronidazole (MTZ) and fidaxomicin (FDX). Eligible studies were randomised controlled trials (RCTs) including adults with any severity of CDI that was treated with VCM, MTZ or FDX. The NMA was performed using a Bayesian framework, using a fixed-effects model. The searches identified seven publications for inclusion, which provided five RCTs for VCM versus MTZ, and three RCTs for FDX versus VCM. The NMA showed that for clinical cure rate, there was no difference for FDX versus VCM, and there was a significant difference in favour of FDX versus MTZ (odds ratio [OR]: 1.77; 95% credible interval [CrI] 1.11, 2.83]). For recurrence rate, there was a significant difference in favour of FDX versus both VCM (OR: 0.50; 95% CrI: 0.37, 0.68) and MTZ (OR: 0.44; 95% CrI: 0.27, 0.72). For sustained cure (clinical cure without recurrence), there was a significant difference in favour of FDX versus VCM (OR: 1.61; 95% CrI: 1.27, 2.05) and MTZ (OR: 2.39; 95% CrI: 1.65, 3.47). These findings suggest that FDX and VCM are effective first-line treatments for mild or moderate CDI, whereas MTZ is not, and FDX may be more effective at preventing CDI recurrence than VCM.

Antimicrobial susceptibility and molecular characterisation using whole-genome sequencing of Clostridioides difficile collected in 82 hospitals in Japan between 2014 and 2016

We studied the antimicrobial susceptibility and molecular characteristics, using draft whole-genome sequencing, of Clostridioides (Clostridium) difficile strains before and after treatment in adults with C. difficile infection (CDI) enrolled in a phase III, randomized, nationwide study of fidaxomicin versus vancomycin in Japan (ClinicalTrials.gov identifier NCT02179658). C. difficile strains were cultured from stool samples collected before and after standard treatment with either fidaxomicin or vancomycin.

We studied the antimicrobial susceptibility and molecular characteristics, using draft whole-genome sequencing, of Clostridioides (Clostridium) difficile strains before and after treatment in adults with C. difficile infection (CDI) enrolled in a phase III, randomized, nationwide study of fidaxomicin versus vancomycin in Japan (ClinicalTrials.gov identifier NCT02179658). C. difficile strains were cultured from stool samples collected before and after standard treatment with either fidaxomicin or vancomycin. Overall, 285 C. difficile strains were recovered, with 188 derived from CDI cases at baseline (87 patients received fidaxomicin, and 101 received vancomycin). No strains isolated from episodes of CDI at baseline were shown to have reduced susceptibilities to fidaxomicin (MIC, ≥1 mg/liter) or resistance to vancomycin and metronidazole. Thirty-three sequence types (STs) were identified, the most common being ST17 (n = 61 [32.4%]), ST8 (n = 26 [13.8%]), and ST2 (n = 21 [11.2%]). Core-genome single-nucleotide polymorphism analysis showed that outbreaks of C. difficile were unlikely to have occurred at each hospital. The predominant toxin gene profile was tcdA⁺ tcdB⁺ cdtA-cdtB⁻ (n = 149 [79.3%]). Six of 87 patients who received fidaxomicin harbored C. difficile isolates with reduced fidaxomicin susceptibilities conferred by previously described mutations, Val1143Leu/Gly/Asp in RpoB or Arg89Gly in RpoC or putative mutations, Gln1149Pro in RpoB, or Arg326Cys in RpoC. Allelic exchange studies of these putative mutations were not performed. Prior to fidaxomicin use, we found no C. difficile strains with reduced fidaxomicin susceptibility causing CDI in Japan; however, mutant strains with reduced fidaxomicin susceptibility were detected after fidaxomicin treatment.

Costs of hospital-acquired Clostridium difficile infections: an analysis on the effect of time-dependent exposures using routine and surveillance data

Background

Hospital-acquired infections have not only gained increasing attention clinically, but also methodologically, as a time-varying exposure. While methods to appropriately estimate extra length of stay (LOS) have been established and are increasingly used in the literature, proper estimation of cost figures has lagged behind.

Methods

Analysing the additional costs and reimbursements of Clostridium difficile-infections (CDI), we use a within-main-diagnosis-time-to-exposure stratification approach to incorporate time-varying exposures in a regression model, while at the same time accounting for cost clustering within diagnosis groups.

Results

We find that CDI is associated with €9000 of extra costs, €7800 of higher reimbursements, and 6.4 days extra length of stay. Using a conventional method, which suffers from time-dependent bias, we derive estimates more than three times as high (€23,000, €8000, 21 days respectively). We discuss our method in the context of recent methodological advances in the estimation of the costs of hospital-acquired infections.

Conclusions

CDI is associated with sizeable in-hospital costs. Neglecting the methodological particularities of hospital-acquired infections can however substantially bias results. As the data needed for an appropriate analysis are collected routinely in most hospitals, we recommend our approach as a feasible way for estimating the economic impact of time-varying adverse events during hospital stay.

Extended-pulsed fidaxomicin versus vancomycin for Clostridium difficile infection: EXTEND study subgroup analyses

Poor outcomes following Clostridium difficile infection (CDI) have been associated with advanced age, presence of cancer and C. difficile PCR-ribotype 027. The impact of baseline risk factors on clinical outcomes was evaluated using data from the EXTEND study, in which rate of sustained clinical cure (SCC) in the overall population was significantly higher with an extended-pulsed fidaxomicin (EPFX) regimen than with vancomycin. Patients aged ≥ 60 years received EPFX (fidaxomicin 200 mg twice daily, days 1–5; once daily on alternate days, days 7–25) or vancomycin (125 mg four times daily, days 1–10). We analysed outcomes by advanced age, cancer diagnosis, CDI severity, prior CDI occurrence and infection with PCR-ribotype 027. The primary endpoint was SCC 30 days after end of treatment (EOT; clinical response at test-of-cure with no subsequent recurrence). SCC rates 30 days after EOT did not differ significantly between EPFX (124/177, 70.1%) and vancomycin (106/179, 59.2%) regardless of age, cancer diagnosis, CDI severity and prior CDI. In patients with PCR-ribotype 027, SCC rate 30 days after EOT was significantly higher with EPFX (20/25, 80%) than with vancomycin (9/22, 40.9%) (treatment difference, 39.1%; 95% CI, 13.2–64.9; P = 0.006). Subgroup analyses from the EXTEND study suggest that EPFX is efficacious as a potential treatment for CDI regardless of age, cancer diagnosis, infection with PCR-ribotype 027, CDI severity or prior CDI. ClinicalTrials.gov identifier: NCT02254967.

The Fatty Acid Synthesis Protein Enoyl-ACP Reductase II (FabK) is a Target for Narrow-Spectrum Antibacterials for Clostridium difficile Infection

Clostridium difficile infection (CDI) is an antibiotic-induced microbiota shift disease of the large bowel. While there is a need for narrow-spectrum CDI antibiotics, it is unclear which cellular proteins are appropriate drug targets to specifically inhibit C. difficile. We evaluated the enoyl-acyl carrier protein (ACP) reductase II (FabK), which catalyzes the final step of bacterial fatty acid biosynthesis. Bioinformatics showed that C. difficile uses FabK as its sole enoyl-ACP reductase, unlike several major microbiota species. The essentiality of fabK for C. difficile growth was confirmed by failure to delete this gene using ClosTron mutagenesis and by growth inhibition upon gene silencing with CRISPR interference antisense to fabK transcription or by blocking protein translation. Inhibition of C. difficile's FASII pathway could not be circumvented by supply of exogenous fatty acids, either during fabK's gene silencing or upon inhibition of the enzyme with a phenylimidazole-derived inhibitor (1). The inability of fatty acids to bypass FASII inhibition is likely due to the function of the transcriptional repressor FapR. Inhibition of FabK also inhibited spore formation, reflecting the enzyme's role in de novo fatty acid biosynthesis for the formation of spore membrane lipids. Compound 1 did not inhibit growth of key microbiota species. These findings suggest that C. difficile FabK is a druggable target for discovering narrow-spectrum anti- C. difficile drugs that treat CDI but avoid collateral damage to the gut microbiota.

Generation of Markerless Deletions in the Nosocomial Pathogen Clostridium difficile by Induction of DNA Double-Strand Breaks

Most sequenced bacterial genomes contain genes encoding proteins of unknown or hypothetical function. To identify a phenotype for mutations in such genes, deletion is the preferred method for mutagenesis because it reduces the likelihood of polar effects, although it does not eliminate the possibility. Allelic exchange to produce deletions is dependent on the length of homologous regions used to generate merodiploids. Shorter regions of homology resolve at lower frequencies. The work presented here demonstrates the utility of inducing DNA double-strand breaks to increase the frequency of merodiploid resolution in Clostridium difficile. Using this approach, we reveal the roles of two genes, encoding homologues of AddAB, in survival following DNA damage. The method is readily applicable to the production of deletions in C. difficile and expands the toolbox available for genetic analysis of this important anaerobic pathogen.

Clostridium difficile is an important nosocomial pathogen associated with potentially fatal disease induced by the use of antibiotics. Genetic characterization of such clinically important bacteria is often hampered by lack of availability of suitable tools. Here, we describe the use of I-SceI to induce DNA double-strand breaks, which increase the frequency of allelic exchange and enable the generation of markerless deletions in C. difficile. The usefulness of the system is illustrated by the deletion of genes encoding putative AddAB homologues. The ΔaddAB mutants are sensitive to ultraviolet light and the antibiotic metronidazole, indicating a role in homologous recombination and the repair of DNA breaks. Despite the impairment in recombination, the mutants are still proficient for induction of the SOS response. In addition, deletion of the fliC gene, and subsequent complementation, reveals the importance of potential regulatory elements required for expression of a downstream gene encoding the flagellin glycosyltransferase.

IMPORTANCE Most sequenced bacterial genomes contain genes encoding proteins of unknown or hypothetical function. To identify a phenotype for mutations in such genes, deletion is the preferred method for mutagenesis because it reduces the likelihood of polar effects, although it does not eliminate the possibility. Allelic exchange to produce deletions is dependent on the length of homologous regions used to generate merodiploids. Shorter regions of homology resolve at lower frequencies. The work presented here demonstrates the utility of inducing DNA double-strand breaks to increase the frequency of merodiploid resolution in Clostridium difficile. Using this approach, we reveal the roles of two genes, encoding homologues of AddAB, in survival following DNA damage. The method is readily applicable to the production of deletions in C. difficile and expands the toolbox available for genetic analysis of this important anaerobic pathogen.

Impact evaluation of a Critical Pathway for patients with Clostridium difficile infection: A pre-post analysis in a Third Level Referral Center

BACKGROUND

Clostridium Difficile Infections (CDIs) have been increasing both in incidence and in severity, representing a big public health concern.

AIM

The aim of this study was to evaluate the impact of a recently implemented Critical Pathway (CP) focused on patients with CDI in an Italian Teaching Hospital.

METHODS

The CP implementation consisted of intervention aimed to faster diagnosis and appropriateness in admission and discharge point of care; activation of a multidisciplinary team; staff training; information to patients and caregivers. In a pre-post retrospective observational study, volume, process and outcome indicators were analyzed.

FINDINGS

A total of 228 patients (128 in 2013 and 100 in 2016) were included. A decrease in the absolute number of access to the Emergency Department (p=0.02) and an increase in hospitalization in more appropriate ward (ie gastroenterology ward, p<0.001) were found. The median hospital length of stay decreased from 20.5 (12.5-31) days in 2013 to 16.5 (7-31) days in 2016 (p=0.05). With regards to outcome indicators, an increase of discharge to home and a decrease of discharge to long term facilities were showed (p=0.01 both). Despite a reduction, no statically significant differences in mortality between 2013 and 2016 were revealed by the analysis.

CONCLUSION

In conclusion, we found quality improvement in patient hospital management. Our experience confirms that the implementation of the CP increases the appropriateness in hospital quality of care.

Gastrointestinal Tract Disorders in Older Age

Considering an increase in the life expectancy leading to a rise in the elderly population, it is important to recognize the changes that occur along the process of aging. Gastrointestinal (GI) changes in the elderly are common, and despite some GI disorders being more prevalent in the elderly, there is no GI disease that is limited to this age group. While some changes associated with aging GI system are physiologic, others are pathological and particularly more prevalent among those above age 65 years. This article reviews the most important GI disorders in the elderly that clinicians encounter on a daily basis. We highlight age-related changes of the oral cavity, esophagus, stomach, small and large bowels, and the clinical implications of these changes. We review epidemiology and pathophysiology of common diseases, especially as they relate to clinical manifestation in elderly. Details regarding management of specific disease are discussed in detail if they significantly differ from the management for younger groups or if they are associated with significant challenges due to side effects or polypharmacy. Cancers of GI tract are not included in the scope of this article.

Fosfomycin: mechanisms and the increasing prevalence of resistance

There are challenges regarding increased global rates of microbial resistance and the emergence of new mechanisms that result in microorganisms becoming resistant to antimicrobial drugs. Fosfomycin is a broad-spectrum bactericidal antibiotic effective against Gram-negative and certain Gram-positive bacteria, such as Staphylococci, that interfere with cell wall synthesis. During the last 40 years, fosfomycin has been evaluated in a wide range of applications and fields. Although numerous studies have been done in this area, there remains limited information regarding the prevalence of resistance. Therefore, in this review, we focus on the available data concerning the mechanisms and increasing resistance regarding fosfomycin.

Comparison of the 2010 and 2017 Infectious Diseases Society of America guidelines on the diagnosis and treatment of Clostridium difficile infection

PURPOSE OF REVIEW

To highlights the key changes in the updated Infectious Diseases Society of America and Society for Healthcare Epidemiology of America guidelines with respect to the diagnosis and treatment of Clostridium difficile infection (CDI).

RECENT FINDINGS

CDI continues as a major threat to healthcare institutions and as a community-associated infection related primarily to antibiotic exposure. Infectious Diseases Society of America/Society for Healthcare Epidemiology of America produced extensive CDI guidelines in 2010; in 2018, updated guidance has been published. The new guidelines include key changes with respect to the treatment and diagnosis of CDI.

SUMMARY

Updated, evidence guidelines allow optimization of the diagnosis of CDI and the use of therapeutic interventions, in particular to reduce the risk of recurrent infection.

Fecal microbiota transplantation for treatment of recurrent C. difficile infection: An updated randomized controlled trial meta-analysis

OBJECTIVES

Although systematic evaluation has confirmed the efficacy of fresh fecal microbiota transplantation (FMT) for treatment of recurrent and/or refractory and/or relapse C. difficile infection (RCDI), it lacks the support of well-designed randomized controlled trials (RCTs), and the latest guidelines do not optimize the management of FMT. In this paper, we focus on an in-depth study of fresh FMT and fecal infusion times to guide clinical practice.

METHODS

We reviewed studies in PubMed, Medline, Embase, the Cochrane library and Cochrane Central written in English. The retrieval period was from the establishment of the databases to September 20th, 2018. The retrieval objects were published RCTs of RCDI treated by fresh FMT. The intervention group was fresh FMT group, while the control group included antibiotic therapy or placebo or frozen FMT or capsule. The primary and secondary outcomes were the clinical remission of diarrhea without relapse after 8-17 weeks and the occurrence of severe adverse events, respectively. Subgroup analysis analyzed the effect of single and multiple fecal infusions. Two authors independently completed the information extraction and assessed risk of bias and overall quality of the evidence.

RESULTS

8 randomized controlled trials met the inclusion criteria, involving 537 patients (273 in the fresh FMT group and 264 in the control group). The recurrence rate of clinical diarrhea in the fresh FMT group was 11.0% (30/273), which was significantly lower than the control group (24.6%, 65/264; P < 0.05); the pooled relative risk (RR) was 0.38 (95%CI:0.16-0.87; I2 = 67%; P = 0.02) in the fresh FMT group, and the clinical heterogeneity was significant and random effects model was used; However, there was no significant difference neither for the effect of antibiotic treatment/frozen feces transplanted by enema (RR = 1.07; 95%CI: 0.64-1.80; I2 = 0%; P = 0.79) or capsule/frozen feces transplanted by colonoscopy (RR = 0.42; 95%CI: 0.05-3.94; I2 = 43%; P = 0.45) compared with fresh FMT. The subgroup analysis showed that FMT by multiple infusions could effectively and significantly (RR = 0.24; 95%CI:0.10-0.58; I2 = 0%; P = 0.001) improve the clinical diarrhea remission rate. Most mild to moderate adverse events caused by FMT were self-limited and could be quickly alleviated; no severe adverse events happened because of FMT.

CONCLUSIONS

Overall, the use of fresh feces for bacterial transplantation was the best efficiency for RCDI compared to antibiotic therapy or placebo. The fecal transmission method by enema was not ideal, but capsules or frozen feces transported by colonoscopy could be an alternative treatment compared to fresh FMT. For patients with severe RCDI, multiple fecal transplants can effectively improve their diarrhea remission rate. The focus of future research should be on how to standardize the production of capsules or frozen feces to better guide the clinical management of RCDI patients by FMT.

Clostridium difficile in patients attending tuberculosis hospitals in Cape Town, South Africa, 2014-2015

Background

Diarrhoea due to Clostridium difficile infection (CDI) poses a significant burden on healthcare systems around the world. However, there are few reports on the current status of the disease in sub-Saharan Africa.

Objectives

This study examined the occurrence of CDI in a South African population of tuberculosis patients, as well as the molecular epidemiology and antibiotic susceptibility profiles of C. difficile strains responsible for disease.

Methods

Toxigenic C. difficile in patients with suspected CDI attending two specialist tuberculosis hospitals in the Cape Town area were detected using a PCR-based diagnostic assay (Xpert^® C. difficile). C. difficile strains isolated from PCR-positive specimens were characterised by ribotyping, multilocus variable-number tandem-repeat analysis and antibiotic susceptibility testing.

Results

The period prevalence of CDI was approximately 70.07 cases per 1000 patient admissions. Strains belonging to ribotype 017 (RT017) made up over 95% of the patient isolates and all of them were multi-drug resistant. Multilocus variable-number tandem-repeat analysis revealed several clusters of highly related C. difficile RT017 strains present in tuberculosis patients in several wards at each hospital.

Conclusion

Tuberculosis patients represent a population that may be at an increased risk of developing CDI and, in addition, may constitute a multi-drug resistant reservoir of this bacterium. This warrants further investigation and surveillance of the disease in this patient group and other high-risk patient groups in sub-Saharan Africa.

Current developments in lantibiotic discovery for treating Clostridium difficile infection

INTRODUCTION

Clostridium difficile is a major cause of healthcare-associated diarrhea linked to the misuse of antimicrobials and the corresponding deleterious impact they have on the protective microbiota of the gut. Resistance to agents used to treat C. difficile including metronizadole and vancomycin has been reported highlighting the need for novel agents. Lantibiotics represent a novel class of agents that many studies have highlighted as effective against C. difficile. Areas covered: In this review lantibiotics including nisin, actagardine, mersacidin, NAI-107 and MU-1140 that exhibit good activity against C.difficile, all of which are currently in the preclinical phase of investigation are discussed. The lantibiotic NVB302, which has completed phase I clinical trials for the treatment of C. difficile, is also described. Expert opinion: Lantibiotics represent promising candidates for the treatment of C. difficile infections due to their novel mode of action, which is thought to decrease the potential of resistance developing and the fact they often possess a less deleterious effect on the protective gut microbiota when compared to traditional agents. They are also extremely amenable to bioengineering approaches and the incorporation of synthetic biology to produce more potent variants.

Pomegranate extract specifically inhibits Clostridium difficile growth and toxin production without disturbing the beneficial bacteria in vitro

Objective

The aim of this study was to assess the pomegranate juice against the growth and toxin production of multidrug-resistant Clostridium difficile hypervirulent strain NAP1/027/BI and also against the growth of beneficial bacteria to prevent or suppress C. difficile infection (CDI).

Materials and methods

Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were taken as parameters for the assessment of antimicrobial property of the pomegranate juice. Four different C. difficile hypervirulent strains NAP1/027/BI, Lactococcus lactis spp., Lactobacillus casei, and Bifidobacterium animalis were subjected to the broth dilution method to determine the MIC and MBC. Enzyme-linked immunosorbent assay (ELISA) was performed to determine clostridial toxin B (TcdB) production in the presence of pomegranate juice.

Results

The MIC and MBC of pomegranate juice containing punicalagin were found to be 390 µg/mL for all C. difficile hypervirulent strain NAP1/027/BI, and the growth of L. lactis spp., L. casei, and B. animalis was not inhibited. Pomegranate juice reduced TcdB production in C. difficile hypervirulent strain NAP1/027/BI.

Conclusion

This study highlights the potential of pomegranate juice to reduce CDI without affecting the beneficial bacteria. Pomegranate juice may be a useful antimicrobial agent to prevent or suppress CDI, avoiding the use of antibiotics.

Comparing fecal microbiota transplantation to standard-of-care treatment for recurrent Clostridium difficile infection: a systematic review and meta-analysis

BACKGROUND

The use of fecal microbiota transplantation (FMT) as a treatment option for recurrent Clostridium difficile infection (rCDI) is well established. Various studies have used different forms and administration routes for FMT. We performed a systemic review and meta-analysis to update the clinical knowledge about different FMT modalities for curing rCDI compared with medical treatment (MT).

PATIENTS AND METHODS

We searched PubMed and Medline from inception through 10 May 2018 for randomized control trials (RCTs) comparing FMT (fresh or frozen) versus MT. We used Cochrane Collaboration's Risk of Bias tool to assess bias in the RCTs. We estimated odds ratio (OR) with 95% confidence interval (CI) for each outcome using a random effects model. P values of less than 0.05 were considered significant.

RESULTS

We included seven RCTs comprising a total of 543 patients with recurrent CDI. There was a nonsignificant trend toward resolution of diarrhea following a single fresh FMT infusion compared with frozen FMT and MT (OR=2.45, 95% CI=0.78-7.71, P=0.12, I=69%). Subgroup analysis of fresh FMT vs. frozen FMT showed no difference between the two groups (OR=2.13, 95% CI=0.22-20.41, P=0.51, I=61%). Frozen FMT infusion through upper route versus lower route showed no difference (OR=0.62, 95% CI=0.15-2.54, P=0.51, I=0%). There was a nonsignificant trend favoring multiple treatments with FMT versus multiple courses of MT (OR=3.68, 95% CI=0.74-18.22, P=0.11, I=0%).

CONCLUSION

FMT is a promising treatment modality for rCDI compared with MT alone. Different forms and routes of FMT administration seem to be equally efficacious. In future, more well-designed RCTs directed at homogenous FMT preparation and delivery methods are required to validate these findings.

Antibacterial and antivirulence activities of auranofin against Clostridium difficile

Clostridium difficile is a deadly, opportunistic bacterial pathogen. In the last two decades, C. difficile infections (CDIs) have become a national concern because of the emergence of hypervirulent mutants with increased capability to produce toxins and spores. This has resulted in an increased number of infections and deaths associated with CDI. The scarcity of anticlostridial drugs has led to unsatisfactory cure rates, elevated recurrence rates and permitted enhanced colonization with other drug-resistant pathogens (such as vancomycin-resistant enterococci) in afflicted patients. Therefore, both patients and physicians are facing an urgent need for more effective therapies to treat CDI. In an effort to find new anticlostridial drugs, we investigated auranofin, an FDA-approved oral antirheumatic drug that has recently been found to possess antibacterial activity. Auranofin exhibited potent activity against C. difficile isolates, inhibiting growth at a concentration of 1 µg/mL against 50% of all tested isolates. Auranofin inhibited both toxin production and spore formation, a property lacking in both vancomycin and metronidazole (the primary agents used to treat CDI). Auranofin had a direct protective activity against C. difficile toxin-mediated inflammation and inhibited the growth of vancomycin-resistant enterococci. Auranofin is a promising candidate that warrants further investigation as a treatment option for C. difficile infections.

Prevention of Infection in Adults Receiving Intravenous Antibiotic Treatment via Indwelling Central Venous Access Devices

BACKGROUND

The use of indwelling Central Venous Access Devices (CVADs) is associated with the development of bloodstream infections. When CVADs are used to administer systemic antibiotics, particularly second- or higher-generation cephalosporins, there is a particular risk of developing Clostridium difficile infection. The overall bloodstream infection rate is estimated to be around 1.74 per 1000 Central Venous Catheter (CVC)-days.

OBJECTIVE

We hypothesised that daily oral administration of the anion-binding resin colestyramine (cholestyramine) would help prevent infections in those receiving intravenous antibiotic treatment via CVADs.

METHOD

A small case series is described of adult patients who received regular intravenous antibiotic treatment (ceftriaxone, daptomycin or vancomycin) for up to 40 weeks via indwelling CVADs; this represented a total of 357 CVC-days. In addition to following well-established strategies to prevent C. difficile infection, during the course of the intravenous antibiotic treatment the patients also received daily oral supplementation with 4 g colestyramine.

RESULTS

There were no untoward infectious events. In particular, none of the patients developed any symptoms or signs of C. difficile infection, whereas approximately one case of a bloodstream infection would have been expected.

CONCLUSION

It is suggested that oral colestyramine supplementation may help prevent such infection through its ability to bind C. difficile toxin A (TcdA) and C. difficile toxin B (TcdB); these toxins are able to gain entry into host cells through receptor-mediated endocytosis, while anti-toxin antibody responses to TcdA and TcdB have been shown to induce protection against C. difficile infection sequelae.

Unravelling the Links between Phage Adsorption and Successful Infection in Clostridium difficile

Bacteriophage (phage) therapy is a promising alternative to antibiotics for the treatment of bacterial pathogens, including Clostridiumdifficile. However, as for many species, in C. difficile the physical interactions between phages and bacterial cells have not been studied in detail. The initial interaction, known as phage adsorption, is initiated by the reversible attachment of phage tail fibers to bacterial cell surface receptors followed by an irreversible binding step. Therefore binding can dictate which strains are infected by the phage. In this study, we investigated the adsorption rates and irreversible binding of three C. difficile myoviruses: CDHM1, CDHM3 and CDHM6 to ten strains that represent ten prevalent C. difficile ribotypes, regardless of their ability to infect. CDHM1 and CDHM3 phage particles adsorbed by ~75% to some strains that they infected. The infection dynamics for CDHM6 are less clear and ~30% of the phage particles bound to all strains, irrespective of whether a successful infection was established. The data highlighted adsorption is phage-host specific. However, it was consistently observed that irreversible binding had to be above 80% for successful infection, which was also noted for another two C. difficile myoviruses. Furthermore, to understand if there is a relationship between infection, adsorption and phage tail fibers, the putative tail fiber protein sequences of CDHM1, CDHM3 and CDHM6 were compared. The putative tail fiber protein sequence of CDHM1 shares 45% homology at the amino acid level to CDHM3 and CDHM6, which are identical to each other. However, CDHM3 and CDHM6 display differences in adsorption, which highlights that there is no obvious relationship between putative tail fiber sequence and adsorption. The importance of adsorption and binding to successful infection is often overlooked, and this study provides useful insights into host-pathogen interactions within this phage-pathogen system.

Updates to Clostridium difficile Spore Germination

Germination of Clostridium difficile spores is a crucial early requirement for colonization of the gastrointestinal tract. Likewise, C. difficile cannot cause disease pathologies unless its spores germinate into metabolically active, toxin-producing cells. Recent advances in our understanding of C. difficile spore germination mechanisms indicate that this process is both complex and unique. This review defines unique aspects of the germination pathways of C. difficile and compares them to those of two other well-studied organisms, Bacillus anthracis and Clostridium perfringensC. difficile germination is unique, as C. difficile does not contain any orthologs of the traditional GerA-type germinant receptor complexes and is the only known sporeformer to require bile salts in order to germinate. While recent advances describing C. difficile germination mechanisms have been made on several fronts, major gaps in our understanding of C. difficile germination signaling remain. This review provides an updated, in-depth summary of advances in understanding of C. difficile germination and potential avenues for the development of therapeutics, and discusses the major discrepancies between current models of germination and areas of ongoing investigation.

Encapsulation of Biological Agents in Hydrogels for Therapeutic Applications

Hydrogels are materials specially suited for encapsulation of biological elements. Their large water content provides an environment compatible with most biological molecules. Their crosslinked nature also provides an ideal material for the protection of encapsulated biological elements against degradation and/or immune recognition. This makes them attractive not only for controlled drug delivery of proteins, but they can also be used to encapsulate cells that can have therapeutic applications. Thus, hydrogels can be used to create systems that will deliver required therapies in a controlled manner by either encapsulation of proteins or even cells that produce molecules that will be released from these systems. Here, an overview of hydrogel encapsulation strategies of biological elements ranging from molecules to cells is discussed, with special emphasis on therapeutic applications.

Observational study of chemotherapy-induced Clostridium difficile infection in patients with lung cancer

BACKGROUND

Diarrhea post-antibiotic use is primarily attributed to Clostridium difficile infection (CDI)-induced mucosal lesions, and evidence of CDI in patients undergoing chemotherapy without prior antibiotic treatment is also increasing. However, few studies have investigated the relationship between chemotherapy use and diarrhea. This study aimed to determine whether the incidence of CDI increased in patients with lung cancer undergoing chemotherapy even without prior antibiotic treatment.

METHODS

We conducted a retrospective study and investigated the presence of Clostridium difficile (C. difficile) and its toxins in patients who experience diarrhea during chemotherapy. If grade 2 or higher diarrhea was noted, a stool culture was performed to detect anaerobic organisms and C. difficile toxins A and B.

RESULTS

A total of 345 consecutive patients (492 in terms of chemotherapy regimens) were enrolled in the study. Grade 2 or higher diarrhea was observed in patients using 36 (7.3%) of these regimens, among which CDI without prior antibiotic exposure was confirmed in patients using 8 regimens (22.2%).

CONCLUSIONS

CDI may remain undetected in patients undergoing chemotherapy even in those who had not received antibiotic treatment previously, unless due attention is paid to its possibility. Testing for C. difficile toxins is highly recommended to expedite timely treatment for diarrhea in such patients. Further studies are needed to clarify the relationship between chemotherapy drug use and CDI to facilitate prevention.