Increasing risk of relapse after treatment of Clostridium difficile colitis in Quebec, Canada

Impact of a Reduction in the Use of High-Risk Antibiotics on the Course of an Epidemic of Clostridium difficile-Associated Disease Caused by the Hypervirulent NAP1/027 Strain

A series of measures were implemented, in a secondary/tertiary-care hospital in Quebec, to control an epidemic of nosocomial Clostridium difficile-associated disease (n-CDAD) caused by a virulent strain; these measures included the development of a nonrestrictive antimicrobial stewardship program. Interrupted time-series analysis was used to evaluate the impact of these measures on n-CDAD incidence. From 2003-2004 to 2005-2006, total and targeted antibiotic consumption, respectively, decreased by 23% and 54%, and the incidence of n-CDAD decreased by 60%. No change in n-CDAD incidence was noted after strengthening of infection control procedures (P=.63), but implementation of the antimicrobial stewardship program was followed by a marked reduction in incidence (P=.007). This suggests that nonrestrictive measures to optimize antibiotic usage can yield exceptional results when physicians are motivated and that such measures should be a mandatory component of n-CDAD control. The inefficacy of infection control measures targeting transmission through hospital personnel might be a result of their implementation late in the epidemic, when the environment was heavily contaminated with spores.

Antimicrobial phenotypes and molecular basis in clinical strains of Clostridium difficile

Clostridium difficile remains the leading cause of nosocomial-acquired diarrhea. This study investigated antimicrobial susceptibility patterns of C. difficile over a 3-year period. Three hundred seventeen C. difficile isolates recovered between 2002 and 2004 were analyzed for their susceptibility to erythromycin (ERY), clindamycin (CLI), moxifloxacin (MXF), doxycycline (DOX), vancomycin (VAN), and metronidazole (MTR) by Etest. The molecular basis for resistance was investigated using polymerase chain reaction (PCR) and DNA sequencing. PCR ribotyping was used to differentiate strains. All strains were susceptible to VAN and MTR. Resistance rates to ERY/CLI, MXF, and DOX increased during the study period. Eighty-four (26.5%) strains exhibited resistance against ERY/CLI, MXF, and DOX. Prevalence of resistance genes was as follows: ermB, 83; ermQ, 0; ermFS, 1; tetM, 84; tetP, 0; tetO, 2; and gyrA mutation, 76. These results indicate an increasing trend in the prevalence of combined resistance against macrolide-lincosamide-streptogramin B antibiotics, fluoroquinolones, and tetracycline in C. difficile. The lack of understanding of antibiotic resistance mechanisms in C. difficile and the increased resistant strains warrants further investigations.

Changing epidemiology of Clostridium difficile-associated disease in children

OBJECTIVE

To determine temporal trends in the incidence rate for Clostridium difficile-associated disease (CDAD) in a pediatric patient population.

METHODS

We performed an observational, retrospective cohort study that included children who visited or were admitted to Children's National Medical Center during the period from July 2001 through June 2006. The CDAD incidence rates were determined and examined for changes over time using the Poisson regression method.

RESULTS

A total of 513 patients whose stool specimens tested positive for C. difficile toxin were identified. Of these patients, 61% were children aged 2 years or older. The proportion of patients with CDAD in this age group has steadily increased from 46% in 2001 to 64% in 2006. Largely as a result of an increasing number of cases of community-associated CDAD, the incidence of CDAD increased significantly in the outpatient setting, particularly in the emergency department (1.18 cases per 1,000 visits in 2001 vs 2.47 cases per 1,000 visits in 2006; P=.02). The incidence among inpatients decreased during the study period (1.024 cases per 1,000 patient-days in 2001 vs 0.680 cases per 1,000 patient-days in 2006; P=.004). In the neonatal intensive care unit, C. difficile toxin was detected in stool specimens collected from 22 patients aged from 15 days to 6 months.

CONCLUSION

This study revealed a steady increase in the number of patients seen in the emergency department with community-acquired CDAD. Findings from this study suggest that the characteristics of CDAD in children--a population that has not been considered to be at high risk for this disease in the past--are changing. Further investigations are warranted to explore deviations from the established burdens of the disease and patient risk factors.

Predictors of Clostridium difficile colitis infections in hospitals

Hospital-level predictors of high rates of 'Clostridium difficile-associated disease' (CDAD) were evaluated in over 2300 hospitals across California, Arizona, and Minnesota. American Hospital Association data were used to determine hospital characteristics associated with high rates of CDAD. Significant correlations were found between hospital rates of CDAD, common infections and other identified pathogens. Hospitals in urban areas had higher average rates of CDAD; yet, irrespective of geographic location, hospital rates of CDAD were associated with other infections. In addition, hospitals with 'high CDAD' rates had slower turnover of beds and were more likely to offer transplant services. These results reveal large differences in rates of CDAD across regions. Hospitals with high rates of CDAD have high rates of other common infections, suggesting a need for broad infection control policies.

In vitro activities of 15 antimicrobial agents against 110 toxigenic clostridium difficile clinical isolates collected from 1983 to 2004

The incidence and severity of Clostridium difficile-associated disease (CDAD) is increasing, and standard treatment is not always effective. Therefore, more-effective antimicrobial agents and treatment strategies are needed. We used the agar dilution method to determine the in vitro susceptibility of the following antimicrobials against 110 toxigenic clinical isolates of C. difficile from 1983 to 2004, primarily from the United States: doripenem, meropenem, gatifloxacin, levofloxacin, moxifloxacin, OPT-80, ramoplanin, rifalazil, rifaximin, nitazoxanide, tizoxanide, tigecycline, vancomycin, tinidazole, and metronidazole. Included among the isolates tested were six strains of the toxinotype III, NAP1/BI/027 group implicated in recent U.S., Canadian, and European outbreaks. The most active agents in vitro were rifaximin, rifalazil, tizoxanide, nitazoxanide, and OPT-80 with MICs at which 50% of the isolates are inhibited (MIC(50)) and MIC(90) values of 0.0075 and 0.015 microg/ml, 0.0075 and 0.03 microg/ml, 0.06 and 0.125 microg/ml, 0.06 and 0.125 microg/ml, 0.125 and 0.125 microg/ml, respectively. However, for three isolates the rifalazil and rifaximin MICs were very high (MIC of >256 microg/ml). Ramoplanin, vancomycin, doripenem, and meropenem were also very active in vitro with narrow MIC(50) and MIC(90) ranges. None of the isolates were resistant to metronidazole, the only agent for which there are breakpoints, with tinidazole showing nearly identical results. These in vitro susceptibility results are encouraging and support continued evaluation of selected antimicrobials in clinical trials of treatment for CDAD.

Clostridium difficile—Associated Diarrhea, an Emerging Epidemic: Therapeutic Options

Clostridum difficile—associated disease (CDAD) is the leading cause of infectious diarrhea and is associated with considerable morbidity and mortality. The incidence is estimated to range from 3.4 to 8.4 cases per 1000 hospital admissions, and it has become a growing problem at many institutions. Treatment options for CDAD are limited due to a paucity of new pharmacologic agents and studies examining other potential treatments. Historically oral metronidazole and oral vancomycin have been used as first-line agents in the treating CDAD, however recent reports of treatment failure and recurrence with these agents have surfaced. These reports illustrate a need for novel pharmacologic agents and a thorough review of currently available agents that may have activity against C difficile. Available data on the treatment of CDAD were extracted and reviewed to outline the appropriate management of CDAD.

Clostridium difficile-associated disease: changing epidemiology and implications for management

Clostridium difficile-associated disease (CDAD) is increasingly being reported in many regions throughout the world. The reasons for this are unknown, are likely to be multifactorial, and are the subject of several current investigations. In addition to the upsurge in frequency of CDAD, an increased rate of relapse/recurrence, disease severity and refractoriness to traditional treatment have also been noted. Moreover, severe disease has been reported in non-traditional hosts (e.g. younger age, seemingly healthy, non-institutionalised individuals residing in the community, and some without apparent antimicrobial exposure). A previously uncommon and more virulent strain of C. difficile has been reported at the centre of multiple transcontinental outbreaks. The appearance of this more virulent strain, in association with certain environmental and antimicrobial exposure factors, may be combining to create the 'perfect storm'. It is human nature to be reactive; however, the successful control of C. difficile will require healthcare systems (including administrators, and leadership within several departments such as environmental services, infection control, infectious diseases, gastroenterology, surgery, microbiology and nursing), clinicians, long-term care and rehabilitation facilities, and patients themselves to be proactive in a collaborative effort. Guidelines for the management of CDAD were last published over a decade ago, with the next iteration due in the fall (autumn) of 2007. Several newer therapies are under investigation but it is unclear whether they will be superior to current treatment options.

Clostridium difficile in retail ground meat, Canada

Clostridium difficile was isolated from 12 (20%) of 60 retail ground meat samples purchased over a 10-month period in 2005 in Canada. Eleven isolates were toxigenic, and 8 (67%) were classified as toxinotype III. The human health implications of this finding are unclear, but with the virulence of toxinotype III strains further studies are required.

A comparison of vancomycin and metronidazole for the treatment of Clostridium difficile-associated diarrhea, stratified by disease severity

BACKGROUND

The incidence and severity of Clostridium difficile-associated diarrhea (CDAD) has been increasing, and there have been recent reports of metronidazole treatment failure. Metronidazole is still commonly used as first-line treatment for CDAD but has never been compared with vancomycin in a prospective, randomized, double-blind, placebo-controlled trial. We conducted such a trial, stratifying patients according to disease severity, to investigate whether one agent was superior for treating either mild or severe disease.

METHODS

From October 1994 through June 2002, patients with CDAD were stratified according to whether they had mild or severe disease based on clinical criteria and were randomly assigned to receive oral metronidazole (250 mg 4 times per day) or oral vancomycin (125 mg 4 times per day) for 10 days. Both groups received an oral placebo in addition to the study drug. Patients were followed up for 21 days to assess cure, treatment failure, relapse, or intolerance.

RESULTS

One hundred seventy-two patients were enrolled, and 150 of these patients successfully completed the trial. Among the patients with mild CDAD, treatment with metronidazole or vancomycin resulted in clinical cure in 90% and 98% of the patients, respectively (P=.36). Among the patients with severe CDAD, treatment with metronidazole or vancomycin resulted in clinical cure in 76% and 97% of the patients, respectively (P=.02). Clinical symptoms recurred in 15% of the patients treated with metronidazole and 14% of those treated with vancomycin.

CONCLUSIONS

Our findings suggest that metronidazole and vancomycin are equally effective for the treatment of mild CDAD, but vancomycin is superior for treating patients with severe CDAD.

Detection of Clostridium difficile toxin: comparison of enzyme immunoassay results with results obtained by cytotoxicity assay

Several kinds of laboratory techniques are available to detect Clostridium difficile toxin in fecal samples. Because questions have been raised about the reliability of immunoassays compared to the accepted standard, cytotoxicity assay, we studied three enzyme immunoassays (EIAs) and one rapid EIA, which demonstrated relatively good sensitivities and specificities compared to cytotoxicity assay.

The challenges posed by reemerging Clostridium difficile infection

There have been recent, marked increases in the incidence and severity of Clostridium difficile-associated disease (CDAD). These may be attributable to the emergence of a hypervirulent strain of C. difficile that produces increased levels of toxins A and B, as well as an extra toxin known as "binary toxin." This previously uncommon strain has become epidemic, coincident with its development of increased resistance to fluoroquinolones, the use of which is increasingly associated with CDAD outbreaks. Although not necessarily related to this epidemic strain, unusually severe CDAD has been reported in populations that had previously been thought to be at low risk, including peripartum women and healthy persons living in the community. Challenges posed by the changing epidemiology of CDAD are compounded by current limitations in diagnostic testing, treatment, and infection control. Overcoming these challenges and limitations will require a concerted effort from a variety of sources, including an ongoing partnership between infectious disease clinicians and public health professionals.

Hospital-acquired Clostridium difficile-associated disease in the intensive care unit setting: epidemiology, clinical course and outcome

Background

Clostridium difficile-associated disease (CDAD) is a serious nosocomial infection, however few studies have assessed CDAD outcome in the intensive care unit (ICU). We evaluated the epidemiology, clinical course and outcome of hospital-acquired CDAD in the critical care setting.

Methods

We performed a historical cohort study on 58 adults with a positive C. difficile cytotoxin assay result occurring in intensive care units.

Results

Sixty-two percent of patients had concurrent infections, 50% of which were bloodstream infections. The most frequently prescribed antimicrobials prior to CDAD were anti-anaerobic agents (60.3%). Septic shock occurred in 32.8% of CDAD patients. The in-hospital mortality was 27.6%. Univariate analysis revealed that SOFA score, at least one organ failure and age were predictors of mortality. Charlson score ≥3, gender, concurrent infection, and number of days with diarrhea before a positive C. difficile toxin assay were not significant predictors of mortality on univariate analysis. Independent predictors for death were SOFA score at infection onset (per 1-point increment, OR 1.40; CI95 1.13–1.75) and age (per 1-year increment, OR 1.10; CI95 1.02–1.19).

Conclusion

In ICU patients with CDAD, advanced age and increased severity of illness at the onset of infection, as measured by the SOFA score, are independent predictors of death.

Effect of metronidazole on growth and toxin production by epidemic Clostridium difficile PCR ribotypes 001 and 027 in a human gut model

OBJECTIVES

We compared the behaviour of Clostridium difficile PCR ribotypes 001 and 027 in a human gut model, and compared the responses to metronidazole exposure.

METHODS

Using a human gut model primed with pooled human faeces, gut flora bacterial counts, C. difficile total viable counts, spore counts and cytotoxin titres were determined, following exposure to clindamycin, in the absence or presence of metronidazole.

RESULTS

Duration of cytotoxin production by C. difficile ribotype 027 was markedly longer than that of ribotype 001 (23 versus 13 days, respectively), but peak toxin titres were similar. During toxin production, total C. difficile ribotype 027 populations had higher proportions of vegetative cells than did ribotype 001 (median 56.33 versus 23.54%). Similarly, total C. difficile ribotype 027 populations remained predominantly as vegetative cells for longer than did ribotype 001 (20 versus 9 days). The effects of metronidazole on C. difficile were markedly less than expected. Titres of C. difficile ribotype 001 cytotoxin were reduced but recurred following metronidazole administration. C. difficile ribotype 027 cytotoxin titres in the distal section of the gut model were unaffected by metronidazole. These observations correlated with poor metronidazole concentrations.

CONCLUSIONS

Duration of cytotoxin production by C. difficile ribotype 027 markedly exceeds that of ribotype 001. Sub-optimal gut concentrations of metronidazole, possibly due to inactivation by components of normal gut flora, are associated with continued toxin production. These findings may help to explain the increased severity of symptoms and higher case-fatality ratio associated with infections due to C. difficile ribotype 027.

Implications of the changing face of Clostridium difficile disease for health care practitioners

Recent reported outbreaks of Clostridium difficile-associated disease in Canada have changed the profile of C difficile infections. Historically, C difficile disease was thought of mainly as a nosocomial disease associated with broad-spectrum antibiotics, and the disease was usually not life threatening. The emergence of an epidemic strain, BI/NAP1/027, which produces a binary toxin in addition to the 2 classic C difficile toxins A and B and is resistant to some fluoroquinolones, was associated with large numbers of cases with high rates of mortality. Recently, C difficile has been reported more frequently in nonhospital-based settings, such as community-acquired cases. The C difficile disease is also being reported in populations once considered of low risk (children and young healthy women). In addition, poor response to metronidazole treatment is increasing. Faced with an increasing incidence of C difficile infections and the changing profile of patients who become infected, this paper will reexamine the current concepts on the epidemiology and treatment of C difficile-associated disease, present new hypotheses for risk factors, examine the role of spores in the transmission of C difficile, and provide recommendations that may enhance infection control practices.

Identification, Optimal Management, and Infection Control Measures for Clostridium difficile–Associated Disease in Long-Term Care

Residents of long-term care facilities are at an increased risk of exposure to Clostridium difficile and become more susceptible to infection after receiving antimicrobial therapy. An increasing number and more severe cases of C. difficile-associated disease (CDAD) have been reported over the last few years and have been linked to the emergence of a new, more virulent strain of C. difficile. These serious cases of disease have also been associated with a more atypical clinical presentation and have prompted the need for an improved means of early recognition and identification performed by the nursing staff. This article reviews the pathogenesis and risk factors for CDAD, changing epidemiology of CDAD, and characteristics of the newly identified strain. Also reviewed are the role of nursing in the identification of patients with CDAD; optimal management of CDAD; infection control strategies; and education of health care professionals, residents, and visitors in the long-term care setting.

Natural and experimental infection of neonatal calves with Clostridium difficile

Clostridium difficile toxins were associated with calf diarrhea in a recent retrospective study; however, no causal relationship has been prospectively investigated. This infection study tested whether the oral inoculation of neonatal calves with a toxigenic strain of C. difficile (PCR-ribotype 077) results in enteric disease.

Fourteen 6–24 h old male colostrums-fed Holstein calves, received either three doses of C. difficile (1.4 × 10⁸ ± 3.5 × 10⁸ cfu) (n = 8) or sterile culture broth (n = 6). Calves were euthanized on day 6 or after the onset of diarrhea, whichever came first. Fecal and intestinal samples were blindly cultured for C. difficile, and tested for its toxin A/B (C. difficile TOX A/B II ELISA, Techlab). PCR-ribotyping was used to compare inoculated and recovered isolates.

Diarrhea was observed in all control calves and 3/8 of inoculated calves (p = 0.03), but it did not occur in calves that tested positive for C. difficile toxins. Fecal toxins were identified only from two controls. PCR-ribotyping confirmed the presence of C. difficile PCR-ribotype 077 in samples of all inoculated calves, but not from controls. The identification of five other PCR-ribotypes in 3/8 (37.5%) and 2/6 (33.3%) of inoculated and control calves, respectively, indicated early natural infection (≤24 h of age). Five of 14 cecal samples had C. difficile (p = 0.01). In conclusion, the oral administration of C. difficile PCR-ribotype 077 to neonatal calves resulted in fecal/intestinal colonization but not in detection of toxins, or signs of enteric disease. Further studies are required to investigate the clinical relevance of C. difficile in calves.

Clostridium difficile colitis that fails conventional metronidazole therapy: response to nitazoxanide

OBJECTIVES

Clostridium difficile-associated disease has increased in incidence and severity. Recommended treatments include metronidazole and vancomycin. Recent investigations, however, document the failure of metronidazole to cure a substantial proportion of patients with Clostridium difficile colitis, but oral administration of vancomycin raises concerns over selection of antibiotic-resistant organisms in the hospital environment. We have recently shown that nitazoxanide is as effective as metronidazole in initial therapy for C. difficile colitis. We hypothesized that this drug might be effective in treating patients who fail therapy with metronidazole.

METHODS

In the present study, we identified 35 patients who failed treatment with metronidazole for C. difficile colitis; failure was defined as either no improvement in symptoms or signs of disease (28 patients) after >or= 14 days of treatment with metronidazole or prompt recurrence on at least two occasions after initially responding to such treatment (seven patients). These patients were ill with numerous co-morbidities. Nitazoxanide, 500 mg twice daily, was given for 10 days; results from all patients are included.

RESULTS

Twenty-six (74%) of 35 patients responded to nitazoxanide, of whom seven later had recurrent disease, yielding a cure rate of 19 of 35 (54%) from initial therapy. Three who initially failed and one who had recurrent disease were re-treated with, and responded to, nitazoxanide. Thus, the aggregate cure with nitazoxanide in this difficult-to-treat population was 23 of 35 (66%).

CONCLUSIONS

Nitazoxanide appears to provide effective therapy for patients with C. difficile colitis who fail treatment with metronidazole.

A case of recurrent Clostridium difficile diarrhea

Clostridium difficile is an important and increasingly common cause of nosocomial diarrhea. Recent epidemics of C. difficile-associated disease (CDAD) reveal a pathogen that is becoming more virulent, leading to an increase in disease severity, treatment failures, and relapses. Those of advanced age are at a particular risk of acquiring this debilitating and costly disease. This case describes CDAD recurring in an 87-year-old resident of a long-term care facility, which caused hospitalization. After five days of therapy on oral metronidazole with minimal improvement in diarrheal symptoms, the patient was switched to oral vancomycin. The patient subsequently improved and completed a 14-day course of metronidazole/vancomycin. The patient's stool was recultured shortly before finishing therapy and revealed C. difficile antigen; the patient was asymptomatic at that time, and it was therefore recommended to stop therapy after the 14-day treatment course. The patient was concurrently prescribed lactobacillus, a probiotic, for treatment of CDAD. The use of probiotics in the treatment of CDAD needs further study.

Clinical outcomes of intravenous immune globulin in severe clostridium difficile-associated diarrhea

OBJECTIVES

Our objective was to determine if use of intravenous immune globulin (IVIG) decreases the incidence of mortality, colectomies, and length of stay in the hospital in patients presenting with severe Clostridium difficile-associated diarrhea (CDAD).

METHODS

A retrospective analysis was undertaken of 79 patients who had a positive C. difficile toxin titer and severe disease admitted to the University of Pittsburgh Medical Center Presbyterian between July 2001 and July 2003. Standard therapy for severe CDAD including intravenous metronidazole, oral vancomycin, or vancomycin enema was administered to all patients. Eighteen patients also received IVIG treatment (200-300 mg/kg); these were pair matched by propensity scoring with 18 patients who had the most similar characteristics and severity of CDAD from the available pool of 61 subjects who did not receive IVIG treatment.

RESULTS

No significant difference was observed in the baseline characteristics between the two groups. There were no statistical differences in clinical outcomes as measured by all cause mortality, colectomies, and length of stay.

CONCLUSIONS

These data demonstrate that the use of IVIG in severe CDAD remains unsubstantiated. This study, although limited by a small sample size, does not support the use of IVIG at this dose for severe CDAD outside of a controlled trial.

ICD-9 codes and surveillance for Clostridium difficile-associated disease

We conducted a retrospective cohort study to compare Clostridium difficile–associated disease rates determined by C. difficile–toxin assays and International Classification of Diseases, 9th Revision (ICD-9) codes. The correlation between toxin assay results and ICD-9 codes was good (κ = 0.72, p<0.01). The sensitivity of the ICD-9 codes was 78% and the specificity was 99.7%.

Interruption of recurrent Clostridium difficile-associated diarrhea episodes by serial therapy with vancomycin and rifaximin

Eight women who each experienced 4-8 episodes of Clostridium difficile-associated diarrhea were given a 2-week course of rifaximin therapy when they were asymptomatic, immediately after completing their last course of vancomycin therapy. Seven of the 8 patients experienced no further diarrhea recurrence. The patient who had a recurrence responded to a second course of rifaximin therapy, but rifaximin-resistant C. difficile was recovered after treatment. A controlled trial for treating recurrent Clostridium difficile-associated diarrhea appears to be warranted.

Update on Clostridium difficile associated disease

PURPOSE OF REVIEW

The aim of this article is to report recent changes in the epidemiology of Clostridium difficile associated disease.

RECENT FINDINGS

An epidemic of Clostridium difficile associated disease in Quebec was associated with a threefold increase in incidence and a sharp increase in fatalities. Strain typing of C. difficile isolates from the involved hospitals revealed that 82% were of a single strain (NAP1/027). This strain was found to produce greater than 10 times as much toxin A and toxin B as historic isolates and has been identified in many institutions throughout North America and Europe. Frequent nosocomial use of fluoroquinolones may encourage the spread of this strain as it is fluoroquinolone resistant. An increased rate of community-acquired Clostridium difficile-associated disease has also been noted and, in some cases, without prior antibiotic exposure. Although some studies have suggested an increased failure rate of metronidazole in Clostridium difficile associated disease, it remains the recommended first line treatment for uncomplicated cases. Other antibiotics, a toxin binder, probiotic agents and a vaccine are being tested in clinical trials for efficacy in prevention and treatment of Clostridium difficile associated disease.

SUMMARY

The recent increase in the incidence and severity of Clostridium difficile associated disease may be related, at least in part, to the emergence of a highly virulent, fluoroquinolone-resistant, NAP1/027 strain.

A portrait of the geographic dissemination of the Clostridium difficile North American pulsed-field type 1 strain and the epidemiology of C. difficile-associated disease in Québec

BACKGROUND

An increase in the incidence and severity of Clostridium difficile-associated disease in Québec and the United States has been associated with a hypervirulent strain referred to as North American pulsed-field type 1 (NAP1)/027.

METHODS

In 2005, a prospective study was conducted in 88 Québec hospitals, and 478 consecutive nosocomial isolates of C. difficile were obtained. The isolates were subjected to pulsed-field gel electrophoresis (PFGE) typing, antimicrobial susceptibility testing, and detection of binary toxin genes and tcdC gene deletion. Data on patient age and occurrence of complications were collected.

RESULTS

PFGE typing of 478 isolates of C. difficile yielded 61 PFGE profiles. Pulsovars A (57%), B (10%), and B1 (8%) were predominant. The PFGE profile of pulsovar A was identical to that of strain NAP1. It showed 67% relatedness with 15 other PFGE patterns, among which 11 had both binary toxin genes and a partial tcdC deletion but different antibiotic susceptibility profiles. Pulsovars B and B1 were identical to strain NAP2/ribotype 001. In hospitals showing a predominant clonal A or B-B1 PFGE pattern, incidence of C. difficile-associated disease was 2 and 1.3 times higher, respectively, than in hospitals without any predominant clonal PFGE pattern. Severe disease was twice as frequent among patients with strains possessing binary toxin genes and tcdC deletion than among patients with strains lacking these virulence factors.

CONCLUSIONS

This study helped to quantify the impact of strain NAP1 on the incidence and severity of C. difficile-associated disease in Québec in 2005. The identification of the geographic dissemination of this predominant strain may help to focus regional infection-control efforts.

Past, present, and future therapies for Clostridium difficile-associated disease

OBJECTIVE

To describe and examine the past, present, and potential future treatment options for Clostridium difficile-associated disease (CDAD).

DATA SOURCES

A PubMed search, restricted to English-language articles concerning CDAD, was conducted (1965-October 2006) using the key words Clostridium difficile, diarrhea, vancomycin, metronidazole, immunoglobulin, and recurrence. Additional references were located through review of the bibliographies of cited articles and by visiting www.clinicaltrials.gov.

STUDY SELECTION AND DATA EXTRACTION

Articles related to the clinical manifestations, diagnosis, and treatment of CDAD, as well as articles addressing current issues related to CDAD, were included.

DATA SYNTHESIS

There have been many investigations into CDAD because of the recent increased incidence and morbidity and mortality of the disease. Various studies examining the changing epidemiology and pathogenicity of C. difficile, as well as new therapies for CDAD with agents such as tolevamer and nitazoxanide, are ongoing. In addition, researchers are investigating probiotics and vaccines to evaluate their effectiveness in preventing CDAD and/or preventing recurrences of CDAD. Studies assessing therapies for refractory CDAD are lacking, although case reports have been published citing treatment strategies using vancomycin enemas, intravenous metronidazole, colestipol and cholestyramine, fecal enemas, bowel irrigation, and immunoglobulin. Furthermore, judicious use of antimicrobials, contact precautions, and adequate environmental cleaning are being evaluated in healthcare institutions as methods for controlling and preventing the spread of C. difficile.

CONCLUSIONS

Oral metronidazole is the drug of choice for an initial CDAD episode. Oral vancomycin is an option for patients who cannot take or fail treatment with oral metronidazole. Clinical trials are necessary to define the therapy for initial CDAD that is most appropriate and produces lower recurrence rates compared with oral metronidazole or vancomycin treatment. Moreover, appropriate treatment for patients with multiple recurrences of or refractory CDAD needs to be determined. More studies are also needed assessing prevention of recurrences of CDAD.

In vitro susceptibility of Clostridium difficile clinical isolates from a multi-institutional outbreak in Southern Québec, Canada

Clostridium difficile isolates from a 2004 outbreak in Québec, Canada, were all found to be susceptible to metronidazole, vancomycin, rifampin, and meropenem but resistant to bacitracin, cefotaxime, ciprofloxacin, and levofloxacin, and most (>80%) were resistant to ceftriaxone, clarithromycin, gatifloxacin, and moxifloxacin. The predominant NAP1 isolates were susceptible to clindamycin, while the NAP2 isolates were resistant.

Review article: tolevamer, a novel toxin-binding polymer: overview of preclinical pharmacology and physicochemical properties

BACKGROUND

Tolevamer is a novel toxin-binding polymer that is currently being investigated in clinical trials for the treatment of patients who have Clostridium difficile-associated diarrhoea.

AIMS

To summarize the results of in vitro and in vivo preclinical studies of tolevamer. In contrast to antibiotics, tolevamer binds C. difficile toxins to interrupt toxin-mediated intestinal inflammation and tissue damage, and does not demonstrate direct antimicrobial activity.

METHODS

Pharmacokinetics/pharmacodynamics were studied in rats and dogs; efficacy was studied in a hamster model.

RESULTS

Studies in rats and dogs indicate that tolevamer is essentially non-absorbed from the gastrointestinal tract and show that drug interactions with commonly used therapies are unlikely. Pharmacologic studies indicate that tolevamer reduces disease severity and recurrence rates in the hamster model of C. difficile-associated diarrhoea and blocks the enterotoxic effects of toxin A in rat ileum. The binding parameters calculated for the interaction of tolevamer with toxins A and B provide a reasonable physicochemical model that supports the potential clinical utility of tolevamer.

CONCLUSIONS

These preclinical results are consistent with the effectiveness and safety profile of tolevamer observed in clinical studies in patients with C. difficile-associated diarrhoea.

Antimicrobial therapy of Clostridium difficile-associated diarrhea

Clostridium difficile-associated diarrhea (CDAD) is the most common etiologically-defined cause of hospital-acquired diarrhea. Caused by the toxins of certain strains of C difficile, CDAD represents a growing concern, with epidemic outbreaks in some hospitals where very aggressive and difficult-to-treat strains have recently been found. Incidence of CDAD varies ordinarily between 1 to 10 in every 1,000 admissions. Evidence shows that CDAD increases morbidity, length of stay, and costs. This article described the clinical manifestations of CDAD, related risk factors, considerations for confirming CDAD, antimicrobial and non-antimicrobial treatment of CDAD, and issues related to relapses. The article concludes with a discussion of recent epidemic outbreaks involving CDAD.

tcdC genotypes associated with severe TcdC truncation in an epidemic clone and other strains of Clostridium difficile

Severe Clostridium difficile associated disease is associated with outbreaks of the recently described BI/NAP1 epidemic clone. This clone is characterized by an 18-bp deletion in the tcdC gene and increased production of toxins A and B in vitro. TcdC is a putative negative regulator of toxin A&B production. We characterized tcdC genotypes from a collection of C. difficile isolates from a hospital that experienced an outbreak caused by the BI/NAP1 epidemic clone. Sequence analysis of tcdC was performed on DNA samples isolated from 199 toxigenic C. difficile isolates (31% BI/NAP1) from 2001 and 2005. Sequences obtained from 36 (18.6%) isolates predicted wild-type TcdC (232 amino acid residues), whereas 12 (6.1%) isolates had tcdC genotypes with previously described 18- or 39-bp deletions. The remaining isolates comprised 15 unique genotypes. Of these, 5 genotypes contain 18- or 36-bp deletions. Of these five genotypes, one is characterized by a single nucleotide deletion at position 117 resulting in a frameshift that introduces a stop codon at position 196, truncating the predicted TcdC to 65 amino acid residues. All 62 of the isolates in this collection comprising the epidemic clone are characterized by this genotype. This result suggests that severe truncation of TcdC is responsible for the increased toxin production observed in strains belonging to the BI/NAP1 clone and that the 18-bp deletion is probably irrelevant to TcdC function. Further investigations are required to determine the effect of this and other tcdC genotypes on toxin production and clinical disease.

Trends in antimicrobial resistance in health care-associated pathogens and effect on treatment

Antimicrobial resistance in health care-associated pathogens is a growing concern for health care and for public health. A recent shift in the epidemiological profile of methicillin-resistant Staphylococcus aureus has resulted not only in health care-associated infections but now, also, in community-associated infections. Reports have described S. aureus exhibiting decreased susceptibility and, even, resistance to vancomycin. The rate of vancomycin resistance among enterococci may be leveling; however, vancomycin resistance in Enterococcus faecium has already achieved high levels. Multidrug resistance in Pseudomonas aeruginosa is increasing, and carbapenem-resistant Klebsiella strains are emerging. Acinetobacter species cause a minority of health care-associated pneumonias due to gram-negative organisms, but a growing proportion is resistant to carbapenems and third-generation cephalosporins. Recent increases in the frequency and severity of Clostridium difficile-associated illness are associated with the emergence of a hypervirulent C. difficile strain with increased resistance to the fluoroquinolones. The presence of these and other resistant organisms in health care facilities limits the number of effective antimicrobials available for treatment.

Nitazoxanide for the treatment of Clostridium difficile colitis

BACKGROUND

Clostridium difficile colitis has increased in incidence and severity, and treatment failure with metronidazole therapy has increasingly been documented. It is uncertain whether treatment with vancomycin is more effective than treatment with metronidazole, but concern over the emergence of vancomycin resistance has motivated the search for alternative therapy. Nitazoxanide, a nitrothiazolide, blocks anaerobic metabolism of eukaryocyes and effectively treats intestinal infestation due to Cryptosporidium or Giardia species. At low concentrations, this compound inhibits C. difficile in vitro.

METHODS

We designed a prospective, randomized, double-blind study to compare nitazoxanide to metronidazole in treating hospitalized patients with C. difficile colitis.

RESULTS

Thirty-four patients received metronidazole at a dosage of 250 mg 4 times per day for 10 days, 40 patients received nitazoxanide at a dosage of 500 mg 2 times per day for 7 days, and 36 patients received nitazoxanide at a dosage of 500 mg 2 times per day for 10 days. After 7 days of treatment, 28 (82.4%) of 34 patients had responded to metronidazole therapy, compared with 68 (89.5%) of 76 who had received nitazoxanide therapy (difference, 7.1%; 95% confidence interval, -7.1% to 25.5%). Thirty-one days after beginning treatment, sustained responses were observed in 19 (57.6%) of 33 patients who had received metronidazole therapy for 10 days, compared with 25 (65.8%) of 38 who had received nitazoxanide for 7 days and 26 (74.3%) of 35 who had received nitazoxanide for 10 days (P = .34).

CONCLUSION

Nitazoxanide is at least as effective as metronidazole in treating C. difficile colitis.

Tolevamer, a novel nonantibiotic polymer, compared with vancomycin in the treatment of mild to moderately severe Clostridium difficile-associated diarrhea

BACKGROUND

Current antibiotic therapies for Clostridium difficile-associated diarrhea have limitations, including progression to severe disease, recurrent C. difficile-associated diarrhea, and selection for nosocomial pathogens. Tolevamer, a soluble, high-molecular weight, anionic polymer that binds C. difficile toxins A and B is a unique nonantibiotic treatment option.

METHODS

In this 3-arm, multicenter, randomized, double-blind, active-controlled, parallel-design phase II study, patients with mild to moderately severe C. difficile-associated diarrhea were randomized to receive 3 g of tolevamer per day (n = 97), 6 g of tolevamer per day (n = 95), or 500 mg of vancomycin per day (n = 97). The primary efficacy parameter was time to resolution of diarrhea, defined as the first day of 2 consecutive days when the patient had hard or formed stools (any number) or < or = 2 stools of loose or watery consistency.

RESULTS

In the per-protocol study population, resolution of diarrhea was achieved in 48 (67%) of 72 patients receiving 3 g of tolevamer per day (median time to resolution of diarrhea, 4.0 days; 95% confidence interval, 2.0-6.0 days), in 58 (83%) of 70 patients receiving 6 g of tolevamer per day (median time to resolution of diarrhea, 2.5 days; 95% confidence interval, 2.0-3.0 days), and in 73 (91%) of 80 patients receiving vancomycin (median time to resolution of diarrhea, 2.0 days; 95% confidence interval, 1.0-3.0 days). Tolevamer administered at a dosage of 6 g per day was found to be noninferior to vancomycin administered at a dosage of 500 mg per day with regard to time to resolution of diarrhea (P = .02) and was associated with a trend toward a lower recurrence rate. Tolevamer was well tolerated but was associated with an increased risk of hypokalemia.

CONCLUSIONS

Tolevamer, a novel polystyrene binder of C. difficile toxins A and B, effectively treats mild to moderate C. difficile diarrhea and merits further clinical development.

Update on Clostridium difficile

The most dramatic change in the past several years has been the increased incidence and severity of Clostridium difficile colitis reported from multiple countries. A number of factors have likely contributed to this. One major event has been the emergence of a fluoroquinolone-resistant clone of C. difficile with enhanced virulence properties that is associated with epidemic disease. Also noteworthy is the apparently decreasing effectiveness of the first-line agent metronidazole in treating this disease. Aggressive treatment of severe C. difficile colitis requires a multifaceted approach, including: 1) cessation of antibiotics where possible; 2) oral vancomycin; 3) if an ileus exists, intravenous administration of metronidazole and possibly intracolonic administration of vancomycin; 4) intravenous immunoglobulin if response to therapy is not rapid, or if there are signs of sepsis; and 5) early surgical consultation. Although it is likely that intravenous immunoglobulin contains antibodies against C. difficile toxins, its benefit remains unproven in rigorous clinical trials. Efforts to actively or passively immunize patients at risk are being explored to prevent the increasing morbidity and mortality associated with this disease. However, defining exactly who is at risk for severe C. difficile-associated disease is complex, as cases are being reported in populations not previously believed to be vulnerable.

An update on diagnosis, treatment, and prevention of Clostridium difficile-associated disease

Clostridium difficile is an important cause of nosocomial morbidity and mortality and is implicated in recent epidemics. Data support the treatment of colitis with oral metronidazole in a dose of 1.0 to 1.5 g/d, with oral vancomycin as a second-line agent, not because its efficacy is questioned but because of environmental concerns. Nitazoxanide and other drugs are currently under intense study as alternatives. Treatment of asymptomatic patients is not recommended. Current management strategies appear to be increasingly ineffective, especially for patients who experience multiple recurrences. Biotherapy and vaccination are currently being explored as treatment options for patients who have recurrent disease. Greater attention should be paid to hospital infection control policies and restriction of broad-spectrum antibiotics.

Activities of tizoxanide and nitazoxanide compared to those of five other thiazolides and three other agents against anaerobic species

Agar dilution was used, and MICs of metronidazole, tizoxanide, nitazoxanide, denitrotizoxanide, RM 4803, RM 4807, RM 4809, RM 4819, amoxicillin-clavulanate, and clindamycin were measured against 412 anaerobes. Nitazoxanide, tizoxanide, RM 4807, and RM 4809 were active against all groups, except for gram-positive non-spore-forming rods with 50% minimum inhibitory concentrations (when the latter were excluded) of 1 to 2 microg/ml and 90% minimum inhibitory concentrations of 4 to 8 microg/ml, respectively. Metronidazole MICs were usually lower against all groups except clostridia.

Management and outcomes of a first recurrence of Clostridium difficile-associated disease in Quebec, Canada

BACKGROUND

During an epidemic of Clostridium difficile-associated disease (CDAD) caused by a strain that is a hyper-producer of toxins A and B, the frequency of a first recurrence after metronidazole treatment of the initial episode doubled in 2003-2004, compared with 1991-2002.

METHODS

To examine whether administration of metronidazole as treatment for a first recurrence of CDAD remained appropriate, we reviewed data for patients with CDAD diagnosed in a hospital in Quebec, Canada, during 1991-2005, who experienced a first recurrence. The frequency of a second recurrence within 60 days after the first one was measured using Kaplan-Meier analysis. Cox regression was used for multivariate analysis.

RESULTS

A total of 463 patients had a first recurrence of CDAD, of whom 154 (33.3%) experienced a second recurrence. Independent predictors of a second recurrence were age and duration of hospitalization after the first recurrence; this latter finding suggested that many such episodes were reinfections rather than relapses. Neither choice of treatment drug (metronidazole or vancomycin) nor use of the same drug for treatment of first recurrence, as had been used during the initial episode, was associated with increased risk of a second recurrence. However, 51 patients (11.0%) developed at least 1 complication (i.e., shock, need for colectomy, megacolon, perforation, or death within 30 days) during the first recurrence. Older age, a high leukocyte count, and renal failure at first recurrence were strongly associated with a complicated CDAD.

CONCLUSIONS

Metronidazole is not inferior to vancomycin for treatment of patients with a first recurrence of CDAD, but the risk of complications with any treatment of CDAD may be higher than has previously been documented.

Treatment of Clostridium difficile-associated disease: old therapies and new strategies

Clostridium difficile-associated disease (CDAD) causes substantial morbidity and mortality. The pathogenesis is multifactorial, involving altered bowel flora, production of toxins, and impaired host immunity, often in a nosocomial setting. Current guidelines recommend treatment with metronidazole; vancomycin is a second-line agent because of its potential effect on the hospital environment. We present the data that led to these recommendations and explore other therapeutic options, including antimicrobials, antibody to toxin A, probiotics, and vaccines. Treatment of CDAD has increasingly been associated with failure and recurrence. Recurrent disease may reflect relapse of infection due to the original infecting organism or infection by a new strain. Poor antibody responses to C difficile toxins have a permissive role in recurrent infection. Hospital infection control and pertinent use of antibiotics can limit the spread of CDAD. A vaccine directed against C difficile toxin may eventually offer a solution to the CDAD problem.

What's new in enteric infectious diseases at home and abroad

PURPOSE OF REVIEW

This review was designed to focus on the important research in the area of acute infectious diarrhea published within the past year. PubMed was reviewed for articles published in 2004 and 2005 relating to pathogen-specific diarrhea and for travelers' diarrhea to identify the newly published articles.

RECENT FINDINGS

New studies continue to show the importance of the diarrheagenic Escherichia coli as causes of acute and persistent diarrhea. Enteroaggregative E. coli has recently been shown to be an unrecognized cause of community-acquired diarrhea in infants in the USA. Genetic factors explain an increased susceptibility to travelers' diarrhea among international travelers. Also, poorly non-absorbed rifaximin (< 0.4%) was shown to be an effective drug when used prophylactically to prevent bacterial diarrhea during high risk travel.

SUMMARY

Studies will continue to define the etiology of diarrhea and to better understand the epidemiology and prevention of infectious diarrhea. Antibacterial resistance among enteric bacterial pathogens is a growing problem, leading to the search for newer antibacterial drugs. Diarrhea due to bacterial agents in international travelers can be prevented and treated successfully by antibacterial drugs. The nonabsorbed rifamycin drug, rifaximin, appears to be ideally suited to become the important new drug in prevention and treatment of travelers' diarrhea. Studies are underway to determine the value of the drug in preventing invasive forms of diarrhea during travel to Asia and in the prevention of the commonly occurring post-infectious irritable bowel syndrome.

Toxin production by an emerging strain of Clostridium difficile associated with outbreaks of severe disease in North America and Europe

BACKGROUND

Toxins A and B are the primary virulence factors of Clostridium difficile. Since 2002, an epidemic of C difficile-associated disease with increased morbidity and mortality has been present in Quebec province, Canada. We characterised the dominant strain of this epidemic to determine whether it produces higher amounts of toxins A and B than those produced by non-epidemic strains.

METHODS

We obtained isolates from 124 patients from Centre Hospitalier Universitaire de Sherbrooke in Quebec. Additional isolates from the USA, Canada, and the UK were included to increase the genetic diversity of the toxinotypes tested. Isolate characterisation included toxinotyping, pulsed-field gel electrophoresis (PFGE), PCR ribotyping, detection of a binary toxin gene, and detection of deletions in a putative negative regulator for toxins A and B (tcdC). By use of an enzyme-linked immunoassay, we measured the in-vitro production of toxins A and B by epidemic strain and non-dominant strain isolates.

FINDINGS

The epidemic strain was characterised as toxinotype III, North American PFGE type 1, and PCR-ribotype 027 (NAP1/027). This strain carried the binary toxin gene cdtB and an 18-bp deletion in tcdC. We isolated this strain from 72 patients with C difficile-associated disease (58 [67%] of 86 with health-care-associated disease; 14 [37%] of 38 with community-acquired disease). Peak median (IQR) toxin A and toxin B concentrations produced in vitro by NAP1/027 were 16 and 23 times higher, respectively, than those measured in isolates representing 12 different PFGE types, known as toxinotype 0 (toxin A, median 848 microg/L [IQR 504-1022] vs 54 microg/L [23-203]; toxin B, 180 microg/L [137-210] vs 8 microg/L [5-25]; p<0.0001 for both toxins).

INTERPRETATION

The severity of C difficile-associated disease caused by NAP1/027 could result from hyperproduction of toxins A and B. Dissemination of this strain in North America and Europe could lead to important changes in the epidemiology of C difficile-associated disease.

Clinical manifestations, treatment and control of infections caused by Clostridium difficile

Clostridium difficile should be suspected in patients who present with nosocomial diarrhoea. It is more common in the elderly or in patients with a debilitating underlying condition who have received antimicrobial agents, and up to 20-25% of patients may experience a relapse. The reference method for diagnosis is the cell culture cytotoxin test which detects the presence of toxin B in a cellular culture of human fibroblasts, but recovering C. difficile in culture allows the performance of a ''second-look" cell culture assay that enhances the potential for diagnosis. Oral metronidazole (500 mg tid or 250 mg every 6 hrs) and oral vancomycin (125 mg every 6 hrs) administered for 1014 days have similar therapeutic efficacy, with response rates near 90-97%. C. difficile strains resistant to metronidazole and with intermediate resistance to vancomycin have been described. The administration of probiotics such as Saccharomyces boulardii, Lactobacillus sp. or brewer's yeast for prophylaxis of CDAD remains controversial.

Mortality attributable to nosocomial Clostridium difficile-associated disease during an epidemic caused by a hypervirulent strain in Quebec

BACKGROUND

Since 2002 an epidemic of Clostridium difficile-associated disease (CDAD) caused by a hypervirulent toxinotype III ribotype 027 strain has spread to many hospitals in Quebec. The strain has also been found in the United States, the United Kingdom and the Netherlands. The effects of this epidemic on mortality and duration of hospital stay remain unknown. We measured these effects among patients admitted to a hospital in Quebec during 2003 and 2004.

METHODS

We compared mortality and total length of hospital stay among inpatients in whom nosocomial CDAD developed and among control subjects without CDAD matched for sex, age, Charlson Comorbidity Index score and length of hospital stay up to the diagnosis of CDAD in the corresponding case.

RESULTS

Thirty days after diagnosis 23.0% (37/161) of the patients with CDAD had died, compared with 7.0% (46/656) of the matched control subjects (p < 0.001). Twelve months after diagnosis, mortality was 37.3% (60/161) among patients with CDAD and 20.6% (135/656) among the control subjects (p < 0.001), for a cumulative attributable mortality of 16.7% (95% confidence interval 8.6%-25.2%). Each case of nosocomial CDAD led, on average, to 10.7 additional days in hospital.

INTERPRETATION

This study documented a high attributable mortality among elderly patients with CDAD mostly caused by a hypervirulent strain, which represents a dramatic change in the severity of this infection.

Emergence of fluoroquinolones as the predominant risk factor for Clostridium difficile-associated diarrhea: a cohort study during an epidemic in Quebec

BACKGROUND

Since 2002, an epidemic of Clostridium difficile-associated-diarrhea (CDAD) associated with a high case-fatality rate has involved >30 hospitals in the province of Quebec, Canada. In 2003, a total of 55% of patients with CDAD at our hospital had received fluoroquinolones in the preceding 2 months. It has been suggested that massive use of proton pump inhibitors might have facilitated this epidemic.

METHODS

To delineate the risk of CDAD associated with specific classes of antibiotics and whether this is modulated by concomitant use of proton pump inhibitors and other drugs altering gastric acidity or gastrointestinal motility, we conducted a retrospective cohort study of patients hospitalized in a teaching hospital in Sherbrooke, Canada, during the period of January 2003 through June 2004. We obtained data on 7421 episodes of care corresponding to 5619 individuals. Patients were observed until they either developed CDAD or died or for 60 days after discharge from the hospital. Adjusted hazard ratios (AHRs) were calculated using Cox regression.

RESULTS

CDAD occurred in 293 patients. Fluoroquinolones were the antibiotics most strongly associated with CDAD (AHR, 3.44; 95% confidence interval [CI], 2.65-4.47). Almost one-fourth of all inpatients received quinolones, for which the population-attributable fraction of CDAD was 35.9%. All 3 generations of cephalosporins, macrolides, clindamycin, and intravenous beta-lactam/beta-lactamase inhibitors were intermediate-risk antibiotics, with similar AHRs (1.56-1.89). Proton pump inhibitors (AHR, 1.00, 95% CI, 0.79-1.28) were not associated with CDAD.

CONCLUSIONS

Administration of fluoroquinolones emerged as the most important risk factor for CDAD in Quebec during an epidemic caused by a hypervirulent strain of C. difficile.