Risk Factors for Treatment Failure and Recurrence after Metronidazole Treatment for Clostridium difficile-associated Diarrhea

Clostridium difficile infection: an update on epidemiology, risk factors, and therapeutic options

PURPOSE OF REVIEW

The incidence and severity of Clostridium difficile infection (CDI) around the world has increased over the past 20 years due to the emergence of hypervirulent strains, increased use and misuse of antibiotics, and the increase of susceptible at-risk populations. Treatments currently available for CDI are inadequate to impede the increasing spread and virulence of the infection, avoid recurrence in chronic patients or prevent infection in at-risk populations.

RECENT FINDINGS

New and promising evidence has been presented during the past year, focusing on two major points: preservation of gut microflora and optimization of immune response to CDI and toxins.

SUMMARY

The review aims to summarize the most recent evidence available on the epidemiology, risk factors and treatment of CDI. New antibiotics with selected action on C. difficile and limited effect on microflora (fidaxomicin) and donor fecal transplantation seem to have a relevant efficacy in treating CDI and reducing its recurrence. The use of selected monoclonal antibodies directed against C. difficile toxins in addition to standard therapy is a new, promising approach for the treatment of recurrent cases. Vaccination could be an additional weapon against CDI. New robust data are needed before recommendations can be made to abandon current treatment based on vancomycin and metronidazole and move toward new frontiers.

The appendix may protect against Clostridium difficile recurrence

BACKGROUND & AIMS

Several risk factors have been identified for the development of recurrent Clostridium difficile infection (CDI) that alter host immunity and disrupt colonic flora. Although the function of the appendix has been debated, its active, gut-associated lymphoid tissue and biofilm production indicate potential roles in recovery from initial CDI and protection against recurrent CDI. We investigated whether the presence or absence of an appendix is associated with CDI recurrence.

METHODS

We reviewed the medical records of adult inpatients with CDI who were admitted to a tertiary-care teaching hospital from 2005 to 2007 to identify those with and without an appendix. The primary dependent variable for statistical analysis was CDI recurrence.

RESULTS

In a multivariate analysis of 11 clinical variables, the presence of an appendix was associated inversely with CDI recurrence (P < .0001; adjusted relative risk, .398). Age older than 60 years also was associated with CDI recurrence (P = .0280; adjusted relative risk, 2.44).

CONCLUSIONS

The presence of an appendix has a significant and independent, inverse association with CDI recurrence, but this finding requires validation in a prospective study. Assessing the presence or absence of an appendix might be useful in predicting CDI recurrence.

The anti-sigma factor TcdC modulates hypervirulence in an epidemic BI/NAP1/027 clinical isolate of Clostridium difficile

Nosocomial infections are increasingly being recognised as a major patient safety issue. The modern hospital environment and associated health care practices have provided a niche for the rapid evolution of microbial pathogens that are well adapted to surviving and proliferating in this setting, after which they can infect susceptible patients. This is clearly the case for bacterial pathogens such as Methicillin Resistant Staphylococcus aureus (MRSA) and Vancomycin Resistant Enterococcus (VRE) species, both of which have acquired resistance to antimicrobial agents as well as enhanced survival and virulence properties that present serious therapeutic dilemmas for treating physicians. It has recently become apparent that the spore-forming bacterium Clostridium difficile also falls within this category. Since 2000, there has been a striking increase in C. difficile nosocomial infections worldwide, predominantly due to the emergence of epidemic or hypervirulent isolates that appear to possess extended antibiotic resistance and virulence properties. Various hypotheses have been proposed for the emergence of these strains, and for their persistence and increased virulence, but supportive experimental data are lacking. Here we describe a genetic approach using isogenic strains to identify a factor linked to the development of hypervirulence in C. difficile. This study provides evidence that a naturally occurring mutation in a negative regulator of toxin production, the anti-sigma factor TcdC, is an important factor in the development of hypervirulence in epidemic C. difficile isolates, presumably because the mutation leads to significantly increased toxin production, a contentious hypothesis until now. These results have important implications for C. difficile pathogenesis and virulence since they suggest that strains carrying a similar mutation have the inherent potential to develop a hypervirulent phenotype.

Quantitative proteomic analysis of the heat stress response in Clostridium difficile strain 630

Clostridium difficile is a serious nosocomial pathogen whose prevalence worldwide is increasing. Postgenomic technologies can now be deployed to develop understanding of the evolution and diversity of this important human pathogen, yet little is known about the adaptive ability of C. difficile. We used iTRAQ labeling and 2D-LC-MS/MS driven proteomics to investigate the response of C. difficile 630 to a mild, but clinically relevant, heat stress. A statistically validated list of 447 proteins to which functional roles were assigned was generated, allowing reconstruction of central metabolic pathways including glycolysis, γ-aminobutyrate metabolism, and peptidoglycan biosynthesis. Some 49 proteins were significantly modulated under heat stress: classical heat shock proteins including GroEL, GroES, DnaK, Clp proteases, and HtpG were up-regulated in addition to several stress inducible rubrerythrins and proteins associated with protein modification, such as prolyl isomerases and proline racemase. The flagellar filament protein, FliC, was down-regulated, possibly as an energy conservation measure, as was the SecA1 preprotein translocase. The up-regulation of hydrogenases and various oxidoreductases suggests that electron flux across these pools of enzymes changes under heat stress. This work represents the first comparative proteomic analysis of the heat stress response in C. difficile strain 630, complementing the existing proteomics data sets and the single microarray comparative analysis of stress response. Thus we have a benchmark proteome for this pathogen, leading to a deeper understanding of its physiology and metabolism informed by the unique functional and adaptive processes used during a temperature upshift mimicking host pyrexia.

Best strategies in recurrent or persistent Clostridium difficile infection

BACKGROUND

Clostridium difficile infection (CDI) is the primary cause of antibiotic-associated colitis and 15-25% of nosocomial antibiotic-associated diarrhea. Its clinical manifestations can range from mild diarrhea to toxic megacolon, bowel perforation, septic shock, and death. Over the past decade, more virulent strains have become increasingly common causes, and the incidence of CDI has risen, especially in elderly patients. These developments have led to an increase in recurrent CDI, which is more difficult to treat. This review focuses on recurrent CDI and its treatment.

METHODS

MEDLINE review using search terms Clostridium difficile, Clostridium difficile infection, recurrent Clostridium difficile infection.

RESULTS

A first recurrence may be treated with the same regimen as the first episode. Metronidazole 500 mg q 8 h for 10-14 days is the drug of choice for moderate infection, and vancomycin 125 mg q 6 h for 10-14 days is the drug of choice for severe CDI. Metronidazole should not be used for treatment of subsequent recurrences because of potential neurotoxicity and hepatic toxicity. Second recurrences should be treated with an oral vancomycin course and taper: 125 mg q 6  h × 10-14 days, 125 mg q 12 h × 7 days, 125 mg q 24 h × 7 days, 125 mg q 48-72  h × 2-8 weeks. Alternative agents are fecal bacteriotherapy, a "rifaximin chaser," nitazoxanide, probiotics, and intravenous immunoglobulin. Fidaxomicin has been approved recently. Monoclonal antibodies against C. difficile toxin remain investigational.

CONCLUSION

Treatment of recurrent CDI remains challenging. Because of the lack of high-quality studies, recommendations for treatment are based on expert opinion. Metronidazole and vancomycin are the mainstays of treatment for both the initial infection and the first recurrence. For second recurrences, a vancomycin course plus taper is recommended. For subsequent recurrences, treatment options are many, with no one approach being entirely satisfactory. New drugs (fidaximicin) and treatments (monoclonal antibodies against the causative toxin) appear promising.

Treatment of refractory and recurrent Clostridium difficile infection

The incidence of Clostridium difficile infection (CDI) has increased since 2000, with greater numbers of severe cases reported, in part due to the emergence of a hypervirulent strain. Initial therapy with metronidazole is still recommended for mild to moderate CDI, but vancomycin is recommended for first-line therapy of severe CDI. Colectomy could be life-saving for some patients with severe disease that does not respond to maximal medical therapy. Recurrent CDI is a challenge to treat; no single effective therapy currently exists. Treatments include antibiotics, adjunct probiotics, fecal microbiota transplant and immune approaches. This Review discusses the various therapeutic approaches used for the treatment of refractory and recurrent CDI.

Mouse relapse model of Clostridium difficile infection

Clostridium difficile is the causative agent of primary and recurrent antibiotic-associated diarrhea and colitis in hospitalized patients. The disease is caused mainly by two exotoxins, TcdA and TcdB, produced by the bacteria. Recurrent C. difficile infection (CDI) constitutes one of the most significant clinical issues of this disease, occurs in more than 20% of patients after the first episode, and may be increasing in frequency. However, there is no well-established animal model of CDI relapse currently available for studying disease pathogenesis, prevention, and therapy. Here we report the establishment of a conventional mouse model of recurrence/relapse CDI. We found that the primary episode of CDI induced little or no protective antibody response against C. difficile toxins and mice continued shedding C. difficile spores. Antibiotic treatment of surviving mice induced a second episode of diarrhea, while a simultaneous reexposure of animals to C. difficile bacteria or spores elicited a full spectrum of CDI similar to that of the primary infection. Moreover, mice treated with immunosuppressive agents were prone to more severe and fulminant recurrent disease. Finally, utilizing this model, we demonstrated that vancomycin only delayed disease recurrence, whereas neutralizing polysera against both TcdA and TcdB completely protected mice against CDI relapse. In conclusion, we have established a mouse relapse CDI model that allows for future investigations of the role of the host immune response in the disease's pathogenesis and permits critical testing of new therapeutics targeting recurrent disease.

The effectiveness of sodium dichloroisocyanurate treatments against Clostridium difficile spores contaminating stainless steel

BACKGROUND

Clostridium difficile is a major cause of hospital-associated infective diarrhea, and its spore form can persist for months in the hospital environment. Chlorine-based cleaning agents are recommended for eliminating this reservoir of potential infection.

OBJECTIVES

To investigate the individual contributions of active chlorine, detergent and mechanical action on decontamination of a C difficile contaminated surface.

METHODS

C difficile spores in test soil were dried onto stainless steel strips and exposed to sodium dichloroisocyanurate (NaDCC) or NaDCC combined with detergent (NaDCC+) or exposed to these cleaning formulations combined with wiping and/or detergent precleaning. After set contact times, remaining viable spores from the strips were recovered and enumerated by vortexing with glass beads, followed by membrane filtration.

RESULTS

Compared with NaDCC, the inclusion of detergent in the NaDCC+ formulation did not improve the effectiveness of decontamination in any exposure-only treatment at concentrations tested (P > .05). Combining wiping with exposure to the cleaning formulations improved decontamination effectiveness with further reductions in spore counts of 1.66- and 2.19-log(10) colony-forming units at 2 and 20 minutes, respectively, using NaDCC, and of 2.46 and 2.56 log(10) colony-forming units at 2 and 20 minutes, respectively, using NaDCC+. Precleaning the strips by wiping with detergent before exposure to NaDCC was more effective than wiping with NaDCC or NaDCC+ at 10 and 20 minutes contact times. Wiping with NaDCC+ was more effective than NaDCC only at a 2-minute contact time. Wiping with detergent followed by subsequent wiping with NaDCC (1,000 ppm) was the most effective treatment tested with a 4.00-log(10) reduction observed.

CONCLUSION

Rigorous precleaning with detergent and the associated physical removal of spores through the mechanical action associated with wiping are important factors in achieving effective decontamination of surfaces when using chlorine-based agents.

Neutralization of Clostridium difficile toxin A with single-domain antibodies targeting the cell receptor binding domain

Clostridium difficile is a leading cause of nosocomial infection in North America and a considerable challenge to healthcare professionals in hospitals and nursing homes. The gram-positive bacterium produces two high molecular weight exotoxins, toxin A (TcdA) and toxin B (TcdB), which are the major virulence factors responsible for C. difficile-associated disease and are targets for C. difficile-associated disease therapy. Here, recombinant single-domain antibody fragments (V(H)Hs), which specifically target the cell receptor binding domains of TcdA or TcdB, were isolated from an immune llama phage display library and characterized. Four V(H)Hs (A4.2, A5.1, A20.1, and A26.8), all shown to recognize conformational epitopes, were potent neutralizers of the cytopathic effects of toxin A on fibroblast cells in an in vitro assay. The neutralizing potency was further enhanced when V(H)Hs were administered in paired or triplet combinations at the same overall V(H)H concentration, suggesting recognition of nonoverlapping TcdA epitopes. Biacore epitope mapping experiments revealed that some synergistic combinations consisted of V(H)Hs recognizing overlapping epitopes, an indication that factors other than mere epitope blocking are responsible for the increased neutralization. Further binding assays revealed TcdA-specific V(H)Hs neutralized toxin A by binding to sites other than the carbohydrate binding pocket of the toxin. With favorable characteristics such as high production yield, potent toxin neutralization, and intrinsic stability, these V(H)Hs are attractive systemic therapeutics but are more so as oral therapeutics in the destabilizing environment of the gastrointestinal tract.

Clostridium difficile infection: epidemiology, risk factors and management

The epidemiology of Clostridium difficile infection (CDI) has changed over the past decade. There has been a dramatic worldwide increase in its incidence, and new CDI populations are emerging, such as those with community-acquired infection and no previous exposure to antibiotics, children, pregnant women and patients with IBD. Diagnosis of CDI requires identification of C. difficile toxin A or B in diarrheal stool. The accuracy of current diagnostic tests remains inadequate and the optimal diagnostic testing algorithm has not been defined. The first-line agents for CDI treatment are metronidazole and vancomycin, with the latter being the preferred agent in patients with severe disease as it has significantly superior efficacy. The incidence of metronidazole treatment failures has increased, emphasizing the need to find alternative treatment options. Disease recurrence continues to occur in 20-40% of patients and its treatment remains challenging. In patients with CDI who develop fulminant colitis, early surgical consultation is essential. Intravenous immunoglobulin and tigecycline have been used in patients with severe refractory disease but delaying surgery may be associated with worse outcomes. Infection control measures are key to prevent horizontal transmission of infection. Ongoing research into effective treatment protocols and prevention is essential.

Recent epidemiology of Clostridium difficile infection during hematopoietic stem cell transplantation

Given the limited information on Clostridium difficile infection (CDI) during hematopoietic stem cell transplantation (HSCT), we examined the recent epidemiology of CDI in HSCT recipients at our institution. During the two-yr retrospective study period (2005-2006), 361 transplants were performed: 60% allogeneic and 40% autologous. Among all hospitalized patients in a non-outbreak setting, CDI rates in HSCT recipients were ninefold higher than those in general patients and 1.4-fold higher than those in patients with cancer (24.0 vs. 2.6 vs. 16.8/10,000 patient-days respectively). Sixty-two episodes of CDI occurred in 51 (14%) HSCT recipients: 39 (18%) allogeneic vs. 12 (8%) autologous (p = 0.01). Almost half of CDI episodes occurred within 30 d post-HSCT and 22% before HSCT. Clostridium difficile toxin assay was initially positive in 28% of the first, 31% of the second and 27% of the third stool samples tested. All but one patient responded to therapy with metronidazole or vancomycin. Severe CDI occurred in one patient and recurrent CDI in two patients. CDI is common during HSCT especially in allogeneic transplants during the peri-HSCT period. Prospective studies to better define the epidemiology and identify unique risk factors for CDI and more accurate tests to confirm the diagnosis in this population are needed.

Impact of Clostridium difficile on inflammatory bowel disease

Clostridium difficile infection (CDI) has been increasing in incidence among those with underlying inflammatory bowel disease (IBD) and is associated with substantial morbidity, the need for surgery and even mortality. The similar clinical presentation between CDI and a flare of underlying IBD makes prompt diagnosis essential to prevent deterioration which would accompany an escalation of immunosuppression in the absence of appropriate antibiotic therapy. Classical risk factors (antibiotic or healthcare exposure) or clinical findings (pseudomembranes) may not be found in many IBD patients with CDI and should not be considered essential for entertaining the diagnosis. Enzyme immunoassays detecting both toxins A and B remain the most widely used test for diagnosis and have acceptable sensitivity, but may require testing of multiple samples in select situations. Both vancomycin and metronidazole appear to be effective and treatment with oral vancomycin is preferred in those with severe disease, including those who require hospitalization. Appropriate infection control measures are essential to restrict patient-to-patient spread within healthcare environments and to prevent recurrences. Several novel therapies are currently under study, including new antibiotic agents and monoclonal antibodies targeted against the toxins. There is a need to broaden these studies to the IBD population. There is also the need to prospectively examine whether CDI has long-term disease-modifying consequences in those with underlying IBD.

Results of faecal donor instillation therapy for recurrent Clostridium difficile-associated diarrhoea

We report a success rate of 83% with faecal donor instillation therapy (FDIT) in this retrospective study of 40 patients with recurrent Clostridium difficile-associated diarrhoea (CDAD), treated at a medium sized Norwegian hospital from 1994 through 2008. The stool transplant was instilled either in the duodenum through a gastroscope or in the colon through a colonoscope with next of kin or other household member as donor. In 29 cases (73%) the first treatment was successful, with no documented recurrence of diarrhoeal disease within 80 days. Of the 11 patients failing to respond to the first instillation treatment, 6 patients received a second instillation, 4 of which were successful. A total of 33 patients (83%) were successfully treated with FDIT. Of the 7 non-responders, 5 were seriously ill due to long lasting diarrhoeal disease and co-morbidity and died within 80 days after the procedure, and 2 were believed to have inflammatory bowel disease with response to corticosteroid treatment. No adverse effects of FDIT were observed. In our experience the procedure is easy to perform, well tolerated, effective, and may be a valuable treatment option in selected cases.

Toxin-specific antibodies for the treatment of Clostridium difficile: current status and future perspectives

Therapeutic agents targeting bacterial virulence factors are gaining interest as non-antibiotic alternatives for the treatment of infectious diseases. Clostridium difficile is a Gram-positive pathogen that produces two primary virulence factors, enterotoxins A and B (TcdA and TcdB), which are responsible for Clostridium difficile-associated disease (CDAD) and are targets for CDAD therapy. Antibodies specific for TcdA and TcdB have been shown to effectively treat CDAD and prevent disease relapse in animal models and in humans. This review summarizes the various toxin-specific antibody formats and strategies under development, and discusses future directions for CDAD immunotherapy, including the use of engineered antibody fragments with robust biophysical properties for systemic and oral delivery.

Clostridium difficile infection: An overview of the disease and its pathogenesis, epidemiology and interventions

Clostridium difficile infection (CDI) is the primary cause of antibiotic-associated diarrhea and is a significant nosocomial disease. In the past ten years, variant toxin-producing strains of C. difficile have emerged, that have been associated with severe disease as well as outbreaks worldwide. This review summarizes current information on C. difficile pathogenesis and disease, and highlights interventions used to combat single and recurrent episodes of CDI.

Structural genomics and drug discovery for infectious diseases

The application of structural genomics methods and approaches to proteins from organisms causing infectious diseases is making available the three dimensional structures of many proteins that are potential drug targets and laying the groundwork for structure aided drug discovery efforts. There are a number of structural genomics projects with a focus on pathogens that have been initiated worldwide. The Center for Structural Genomics of Infectious Diseases (CSGID) was recently established to apply state-of-the-art high throughput structural biology technologies to the characterization of proteins from the National Institute for Allergy and Infectious Diseases (NIAID) category A-C pathogens and organisms causing emerging, or re-emerging infectious diseases. The target selection process emphasizes potential biomedical benefits. Selected proteins include known drug targets and their homologs, essential enzymes, virulence factors and vaccine candidates. The Center also provides a structure determination service for the infectious disease scientific community. The ultimate goal is to generate a library of structures that are available to the scientific community and can serve as a starting point for further research and structure aided drug discovery for infectious diseases. To achieve this goal, the CSGID will determine protein crystal structures of 400 proteins and protein-ligand complexes using proven, rapid, highly integrated, and cost-effective methods for such determination, primarily by X-ray crystallography. High throughput crystallographic structure determination is greatly aided by frequent, convenient access to high-performance beamlines at third-generation synchrotron X-ray sources.