Epidemiology of recurrences or reinfections of Clostridium difficile-associated diarrhea

In vitro and in vivo activities of the novel Ketolide RBx 14255 against Clostridium difficile

The MIC(90) of RBx 14255, a novel ketolide, against Clostridium difficile was 4 μg/ml (MIC range, 0.125 to 8 μg/ml), and this drug was found to be more potent than comparator drugs. An in vitro time-kill kinetics study of RBx 14255 showed time-dependent bacterial killing for C. difficile. Furthermore, in the hamster model of C. difficile infection, RBx 14255 demonstrated greater efficacy than metronidazole and vancomycin, making it a promising candidate for C. difficile treatment.

Evaluation of the diagnostic algorithm consisting of enzyme immunoassay for toxins and polymerase chain reaction, for the diagnosis of Clostridium difficile-associated diarrhoea

A total of 1631 stool specimens were tested for Clostridium difficile toxins A and B using an enzyme immunoassay (EIA). C. difficile toxin was detected in 191 (11.7%, 191/1631) cases by EIA. Among the remaining 1440 cases, 102 cases in patients with either antibiotic-associated diarrhoea or hospitalized patients with unexplained leukocytosis (> 15,000/mm³) and fever (≥ 38°C) even though they did not meet the criteria for diarrhoea, were further assessed using a polymerase chain reaction (PCR) for the toxin B gene (tcdB). Thirty-four cases were tcdB-positive (33.3%, 34/102). A total of 225 cases (13.8%, 225/1631) had a stool test result positive for C. difficile toxins. Among these, 145 cases were diagnosed with C. difficile-associated diarrhoea (CDAD): 80.7% (117/145) using the EIA and 19.3% (28/145) using the PCR. In our study, the 2-test algorithm including EIA-toxin assay and PCR test made a more accurate diagnosis of CDAD. Furthermore, the application of clinical situations may be effective in the selection of patients who need confirmatory testing.

The potential economic value of screening hospital admissions for Clostridium difficile

Asymptomatic Clostridium difficile carriage has a prevalence reported as high as 51-85 %; with up to 84 % of incident hospital-acquired infections linked to carriers. Accurately identifying carriers may limit the spread of Clostridium difficile. Since new technology adoption depends heavily on its economic value, we developed an analytic simulation model to determine the cost-effectiveness screening hospital admissions for Clostridium difficile from the hospital and third party payer perspectives. Isolation precautions were applied to patients testing positive, preventing transmission. Sensitivity analyses varied Clostridium difficile colonization rate, infection probability among secondary cases, contact isolation compliance, and screening cost. Screening was cost-effective (i.e., incremental cost-effectiveness ratio [ICER] ≤ $50,000/QALY) for every scenario tested; all ICER values were ≤ $256/QALY. Screening was economically dominant (i.e., saved costs and provided health benefits) with a ≥10.3 % colonization rate and ≥5.88 % infection probability when contact isolation compliance was ≥25 % (hospital perspective). Under some conditions screening led to cost savings per case averted (range, $53-272). Clostridium difficile screening, coupled with isolation precautions, may be a cost-effective intervention to hospitals and third party payers, based on prevalence. Limiting Clostridium difficile transmission can reduce the number of infections, thereby reducing its economic burden to the healthcare system.

The Clostridium difficile spo0A gene is a persistence and transmission factor

Clostridium difficile is a major cause of chronic antibiotic-associated diarrhea and a significant health care-associated pathogen that forms highly resistant and infectious spores. Spo0A is a highly conserved transcriptional regulator that plays a key role in initiating sporulation in Bacillus and Clostridium species. Here, we use a murine model to study the role of the C. difficile spo0A gene during infection and transmission. We demonstrate that C. difficile spo0A mutant derivatives can cause intestinal disease but are unable to persist within and effectively transmit between mice. Thus, the C. difficile Spo0A protein plays a key role in persistent infection, including recurrence and host-to-host transmission in mice.

Adherence of Clostridium difficile spores to Caco-2 cells in culture

Clostridium difficile is the causative agent of the majority of antibiotic associated diarrhoea cases. C. difficile spores are recognized as the persistent and infectious morphotype as well as the vehicle of transmission of CDI. However, there is a lack of knowledge on how C. difficile spores interact with the host's epithelial surfaces. In this context, we have characterized the ability of C. difficile spores to adhere to human Caco-2 cells. Despite the similarities in spore-surface hydrophobicity between spores of C. difficile and Clostridium perfringens (another enteric pathogen that also sporulates in the gut), spores of C. difficile adhere better to Caco-2 cells. Adherence to Caco-2 cells was significantly reduced when C. difficile spores were treated with trypsin. Sonication of C. difficile spores altered the ultrastructure of the outermost exosporium-like structure, releasing two protein species of ~40 kDa and significantly reduced spore hydrophobicity and adherence to Caco-2 cells. Using a trifunctional cross-linker, we were able to co-immunoprecipitate four protein species from the surface of Caco-2 cells. In conclusion, this study provides evidence that C. difficile spores adhere to human intestinal enterocyte-like cells through spore- and enterocytic-surface-specific ligand(s) and/or receptor(s).

Sensitive quantification of Clostridium difficile cells by reverse transcription-quantitative PCR targeting rRNA molecules

We established a sensitive and accurate quantification system for Clostridium difficile in human intestines, based on rRNA-targeted reverse transcription-quantitative PCR (RT-qPCR). We newly developed a species-specific primer set for C. difficile targeting 23S rRNA gene sequences. Both the vegetative cells and the spores of C. difficile in human feces were quantified by RT-qPCR, with a lower detection limit of 10(2.4) cells/g of feces. In an analysis of the feces of residents (n = 83; age, 85 ± 8 years) and staff (n = 19; age, 36 ± 10 years) at a care facility for the elderly, C. difficile was detected by RT-qPCR in 43% of the residents (average count, log(10) 4.0 ± 2.0 cells/g of feces) and 16% of the staff (average count, log(10) 2.2 ± 0.1 cells/g of feces); these rates were far higher than those detected by qPCR (residents, 19%; staff, 0%) or selective cultivation (residents, 18%; staff, 5%). Another analysis of healthy adults (n = 63; age, 41 ± 11 years) also revealed the significant carriage rate of C. difficile in the intestines (detection rate, 13%; average count, log(10) 4.9 ± 1.2 cells/g of feces). From these results, it was suggested that rRNA-targeted RT-qPCR should be an effective tool for analyzing population levels of C. difficile in the human intestine.

Clostridium difficile: epidemiology, pathogenesis, management, and prevention of a recalcitrant healthcare-associated pathogen

Clostridium difficile is the leading cause of healthcare-associated infectious diarrhea. Although C difficile is part of normal flora in some healthy individuals, patients with selective risk factors are often vulnerable to the toxigenic potential of this virulent healthcare pathogen. The spectrum of C difficile infection (CDI) is highly variable, ranging from mild to severe illness, presenting with single to multiple disease recurrences. Current approaches to treatment are based on severity of illness, number of recurrences, and clinical presentation. Oral vancomycin and metronidazole have formed the foundation for treatment of CDI, but therapeutic failures are commonly reported, especially involving hypervirulent clones. Alternative therapies, including newer antimicrobials, probiotics, immunotherapy, and fecal transplantation, have all met with varying degrees of efficacy. Although toxigenic culture (TC) testing from anaerobic culture remains the gold standard, newer technologies, including enzyme immunoassay, common antigen (glutamate dehydrogenase) testing, and real-time polymerase chain reaction (PCR) are less time-consuming and rapid. However, TC and PCR have reported high specificity and sensitivity when compared with other laboratory tests. Because of the significant morbidity and mortality associated with CDI, a high index of suspicion is warranted. Prevention and eradication of CDI require a multidisciplinary approach, including early disease recognition through appropriate surveillance, implementation of effective contact isolation strategies, adherence to environmental controls, judicious hand hygiene, evidence-based treatment, and management that includes antibiotic stewardship, continuous education of healthcare workers, and administrative support.

Clinical and microbiologic characteristics of tcdA-negative variant Clostridium difficile infections

Background

The tcdA-negative variant (A^-B⁺) of Clostridium difficile is prevalent in East Asian countries. However, the risk factors and clinical characteristics of A^-B⁺C. difficile infections (CDI) are not clearly documented. The objective of this study was to investigate these characteristics.

Methods

From September 2008 through January 2010, the clinical characteristics, medication history and treatment outcomes of CDI patients were recorded prospectively. Toxin characterization and antibiotic susceptibility tests were performed on stool isolates of C. difficile.

Results

During the study period, we identified 22 cases of CDI caused by tcdA-negative tcdB-positive (A^-B⁺) strains and 105 cases caused by tcdA-positive tcdB-positive (A⁺B⁺) strains. There was no significant difference in disease severity or clinical characteristics between the two groups. Previous use of clindamycin and young age were identified as significant risk factors for the acquisition of A^-B⁺ CDI (OR = 4.738, 95% CI 1.48–15.157, p = 0.009 and OR = 0.966, 95% CI 0.935–0.998, p = 0.038, respectively) in logistic regression.

Rates of resistance to clindamycin were 100% and 69.6% in the A^-B⁺ and A⁺B⁺ isolates, respectively (p = 0.006), and the ermB gene was identified in 17 of 21 A^-B⁺ isolates (81%). Resistance to moxifloxacin was also more frequent in the A^-B⁺ than in the A⁺B⁺ isolates (95.2% vs. 63.7%, p = 0.004).

Conclusions

The clinical course of A^-B⁺ CDI is not different from that of A⁺B⁺ CDI. Clindamycin use is a significant risk factor for the acquisition of tcdA-negative variant strains.

Clinical and economic burden of Clostridium difficile infection in Europe: a systematic review of healthcare-facility-acquired infection

PubMed, EMBASE and conference abstracts were reviewed systematically to determine the clinical and economic burden associated with Clostridium difficile infection (CDI) acquired and treated in European healthcare facilities. Inclusion criteria were: published in the English language between 2000 and 2010, and study population of at least 20 patients with documented CDI acquired/treated in European healthcare facilities. Data collection was completed by three unblinded reviewers using the Cochrane Handbook and PRISMA statement. The primary outcomes were mortality, recurrence, length of hospital stay (LOS) and cost related to CDI. In total, 1138 primary articles and conference abstracts were identified, and this was narrowed to 39 and 30 studies, respectively. Data were available from 14 countries, with 47% of studies from UK institutions. CDI mortality at 30 days ranged from 2% (France) to 42% (UK). Mortality rates more than doubled from 1999 to 2004, and continued to rise until 2007 when reductions were noted in the UK. Recurrent CDI varied from 1% (France) to 36% (Ireland); however, recurrence definitions varied between studies. Median LOS ranged from eight days (Belgium) to 27 days (UK). The incremental cost of CDI was £4577 in Ireland and £8843 in Germany, after standardization to 2010 prices. Country-specific estimates, weighted by sample size, ranged from 2.8% to 29.8% for 30-day mortality and from 16 to 37 days for LOS. CDI burden in Europe was most commonly described using 30-day mortality, recurrence, LOS and cost data. The continued spread of CDI and resultant healthcare burden underscores the need for judicious use of antibiotics.

Michigan Clostridium difficile hospital discharges: frequency, mortality, and charges, 2002-2008

OBJECTIVE

Clostridium difficile (C. difficile) causes an intestinal bacterial infection of increasing importance in Michigan residents and health-care facilities. The specific burden and health-care costs of C. difficile infection (CDI) were previously unknown. We evaluated the frequency, mortality, and health-care charges of CDI from Michigan hospital discharge data.

METHODS

The Michigan Department of Community Health purchased discharge data from all Michigan acute care hospitals from the Michigan Health and Hospital Association. We extracted all hospital discharges from 2002 through 2008 containing the International Classification of Diseases, Ninth Revision code for intestinal infection due to C. difficile. Discharges were stratified by principle diagnosis and comorbidity level. Total hospitalization charges were standardized to the 2008 U.S. dollar.

RESULTS

From 2002 through 2008, 68,686 hospital discharges with CDI occurred. The annual rate increased from 463.1 to 1096.5 CDI discharges per 100,000 discharges. CDI discharge rates were substantially higher among the elderly, females, and black people. Of all CDI discharges, 5,924 (8.6%) patients died. The mean total health-care charge for the time period was $67,149, and the annual mean increased 35% from 2002 to 2008. Hospital charges varied significantly by race/ethnicity and age. People with Medicaid insurance accrued the highest charges.

CONCLUSION

Across Michigan, the CDI burden is growing substantially and affecting vulnerable populations. Surveillance utilizing hospital discharge data can illuminate trends and inform intervention targets. To reduce disease and health-care charges, increased prevention and infection-control efforts should be directed toward high-risk populations, such as the elderly.

Molecular and microbiological characterization of Clostridium difficile isolates from single, relapse, and reinfection cases

In this study, we investigated the correlation between the microbiological characteristics of Clostridium difficile clinical isolates and the recurrence of C. difficile-associated disease (CDAD). Twenty C. difficile isolates recovered from 20 single infection cases and 53 isolates from 20 recurrent cases were analyzed by pulsed-field gel electrophoresis (PFGE) and PCR ribotyping, and the cytotoxicity, antimicrobial susceptibility, and sporulation/germination rates of the isolates were examined. Recurrent cases were divided into relapse or reinfection cases by the results of C. difficile DNA typing. Among the 20 recurrent cases, 16 cases (80%) were identified to be relapse cases caused by the initial strain and the remaining 4 cases (20%) were identified to be reinfection cases caused by different strains. All 73 isolates were susceptible to both vancomycin and metronidazole, but resistance against clindamycin, ceftriaxone, erythromycin, and ciprofloxacin was found in 87.7%, 93.2%, 87.7%, and 100% of the isolates, respectively. No correlations between DNA typing group, cytotoxicity, and sporulation rate of isolates and infection status, i.e., single, relapse, or reinfection, were observed. However, the isolates recovered from relapse cases showed a significantly higher germination rate when incubated in medium lacking the germination stimulant sodium taurocholate. These results indicate that the germination ability of C. difficile may be a potential risk factor for the recurrence of CDAD.

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.

Clostridium difficile mixed infection and reinfection

Isolates from consecutive Clostridium difficile infection (CDI) fecal samples underwent multilocus sequence typing. Potential reinfections with different genotypes were identified in 88/560 (16%) sample pairs taken 1 to 1,414 days (median, 24; interquartile range [IQR], 1 to 52 days) apart; odds of reinfection increased by 58% for every doubling of time between samples. Of 109 sample pairs taken on the same day, 3 (3%) had different genotypes. Considering samples 0 to 7 days apart as the same CDI, 7% of cases had mixed infections with >1 genotype.

Antimicrobial prophylaxis in women with recurrent urinary tract infections

Recurrent urinary tract infections (UTIs) in women are common, result in considerable morbidity and expense, and can be a management problem for clinicians. Behavioural changes can be useful antimicrobial-sparing measures in the prevention of recurrent UTIs, but antimicrobial prophylaxis may be necessary in those who continue to have recurrences. Continuous prophylaxis, post-coital prophylaxis and intermittent self-treatment with antimicrobials have all been demonstrated to be effective in the prevention of recurrent uncomplicated UTIs. The decision as to which approach to use depends upon the frequency and pattern of recurrences and willingness of the patient to commit to a specific regimen. The risk of adverse events, including antimicrobial resistance, patient's lifestyle and compliance and plans for a pregnancy also need to be considered. The choice of antimicrobial should be based upon the susceptibility pattern of the organisms causing the patient's previous UTIs and history of drug allergies.

Relapse versus reinfection: surveillance of Clostridium difficile infection

Molecular typing was used to examine surveillance definitions for recurrent Clostridium difficile-associated diarrhea. Among 102 patients, 85 had a second episode within 8 weeks, 88% of which were relapses. Of 49 second episodes occurring after > 8 weeks, 65% were relapses. Categorization of a recurrent episode occurring after >8 weeks as a new infection may misrepresent the majority of episodes for surveillance.

Epidemiology and clinical characteristics of Clostridium difficile infection in a Korean tertiary hospital

In order to investigate the incidence, clinical and microbiologic characteristics of Clostridium difficile infection (CDI) in Korea, a prospective observational study was performed. From September 2008 through January 2010, all patients whose stool was tested for toxin assay A&B and/or C. difficile culture were studied for clinical characteristics. Toxin types of the isolates from stool were tested. The mean incidence of CDI per 100,000 patient-days was 71.6 by month (range, 52.5-114.0), and the ratio of CDI to antibiotic-associated diarrhea was 0.23. Among 200 CDI patients, 37.5% (75/200) was severe CDI based on severity score. Clinical outcome of 189 CDI was as followed; 25.9% (49/189) improved without treatment, 84.3% (118/140) achieved clinical cure and attributed mortality was 0.7% (1/140) with the treatment. Recurrence rate was 21.4% (30/140) and cure without recurrence was 66.4% (93/140). The most common type of toxin was toxin A-positive/toxin B-positive strain (77.5%), toxin A-negative/toxin B-positive strains or binary toxin-producing strains comprised 15.4% or 7.1%, respectively. In conclusion, the incidence of CDI in Korea is a little higher than other reports during the non-epidemic setting. We expect that the change of epidemiology and clinical severity in CDI can be evaluated based on these results.

Clostridium difficile infection: monoclonal or polyclonal genesis?

Clostridium difficile is considered to be a leading cause of hospital-acquired diarrhea. C. difficile (CDI) infection shows a high rate of recurrence. There would have to be a predominantly monoclonal mechanism of CDI within individual patients in order for molecular epidemiologic tools such as polymerase chain reaction (PCR) ribotyping to be useful in outbreak investigation or differentiation between infection relapse versus re-infection. It was the aim of our study to determine whether CDI is of monoclonal or of polyclonal genesis. Between December 2009 and June 2010, 11 patients with nosocomial CDI were chosen arbitrarily. Five individual colonies of C. difficile were picked from each of the primary culture plates. Of 55 isolates gained, 47 were available for PCR ribotyping (eight isolates failed attempts to re-culture). Among these 47 isolates, eight different PCR ribotypes were identified. Only one of the 11 patients had a stool sample that yielded more than one ribotype (PCR ribotypes 438 and 232); this 67-year-old female cancer patient was already suffering from recurring diarrhea prior to the fatal episode of colitis which was subsequently investigated. We conclude that polyclonal infections may occasionally occur in patients with CDI. Our findings of predominantly monoclonal origin of CDI within patients suggest that molecular epidemiologic investigations can be used reliably for outbreak investigations or discrimination between relapse and re-infection.

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.

Rifaximin: new therapeutic indication and future directions

BACKGROUND

Rifaximin is a nonabsorbable oral antibiotic that acts locally in the gastrointestinal tract with minimal systemic adverse effects. Rifaximin received new labeling for reduction in the risk of the recurrence of overt hepatic encephalopathy (HE) in patients with advanced liver disease in March of 2010.

OBJECTIVE

This article reviews the pharmacology, pharmacokinetics, and pharmacodynamics of rifaximin. The efficacy and safety of rifaximin in reducing the risk of the recurrence of overt HE in patients with advanced liver disease, the new US Food and Drug Administration-approved indication, is the focus of this review. Emerging data on the use of rifaximin in irritable bowel syndrome (IBS) and Clostridium difficile infection (CDI) are also evaluated.

METHODS

MEDLINE and International Pharmaceutical Abstracts from 1983 to January 31, 2011, were searched using the key terms rifaximin, L/105, secondary hepatic encephalopathy, irritable bowel syndrome, and Clostridium difficile. Ongoing trials were identified using the clinicaltrials.gov Web site. Abstracts from the annual meetings of the American College of Gastroenterology and Digestive Disease Week from 2004 to 2010 and references from relevant articles were reviewed. Only trials examining use of rifaximin in secondary prophylaxis of HE were included. Studies on the efficacy and safety of rifaximin in the treatment of acute episodes of HE have been recently summarized elsewhere and are not reviewed here.

RESULTS

Literature search identified one trial on rifaximin use in secondary prevention of HE, six trials in patients with IBS, and six small studies and case reports in patients with CDI. In a trial of 299 patients, use of rifaximin 550 mg by mouth twice daily for 6 months for prevention of recurrent HE was associated with significantly fewer breakthrough HE episodes compared with placebo (rifaximin 22%, placebo 46%; P < 0.001), with a hazard ratio of 0.42 (95% CI, 0.28-0.64). The rifaximin group also had fewer hospitalizations involving HE compared with placebo (rifaximin 13.6%, placebo 22.6%; P = 0.01), with a hazard ratio of 0.50 (95% CI, 0.29-0.87). Rifaximin improved IBS symptom management in ∼9% more patients than placebo in 2 prospective, randomized, double-blind, placebo-controlled trials of 1260 patients (in the rifaximin group, 40.8% patients reported IBS symptom improvement compared with 31.7% in the placebo group; P < 0.001). The efficacy of rifaximin has been reported for the treatment of refractory or recurrent CDI in small studies, case series, and a case report. Optimal dosing, duration, and role of rifaximin for CDI management is unclear. In clinical trials of rifaximin for prevention of recurrent HE and for nonconstipated IBS, its safety profile was comparable to placebo. In the trial of rifaximin for prevention of recurrent HE, the most common adverse events occurring in 10% to 15% of patients were ascites, dizziness, fatigue, and peripheral edema. Most common adverse effects in IBS trials included abdominal pain, diarrhea, bad taste, headache, and upper respiratory tract infection, occurring in <10% of patients.

CONCLUSIONS

Rifaximin can be an effective option for reduction in the risk of the recurrence of HE in patients with advanced liver disease. Studies suggest that rifaximin provides relief of global symptoms of diarrhea-predominant IBS and bloating. Use of rifaximin in CDI requires further study.

The economic burden of Clostridium difficile

Although Clostridium difficile (C. difficile) is the leading cause of infectious diarrhoea in hospitalized patients, the economic burden of this major nosocomial pathogen for hospitals, third-party payers and society remains unclear. We developed an economic computer simulation model to determine the costs attributable to healthcare-acquired C. difficile infection (CDI) from the hospital, third-party payer and societal perspectives. Sensitivity analyses explored the effects of varying the cost of hospitalization, C. difficile-attributable length of stay, and the probability of initial and secondary recurrences. The median cost of a case ranged from $9179 to $11 456 from the hospital perspective, $8932 to $11 679 from the third-party payor perspective, and $13 310 to $16 464 from the societal perspective. Most of the costs incurred were accrued during a patient's primary CDI episode. Hospitals with an incidence of 4.1 CDI cases per 100 000 discharges would incur costs ≥$3.2 million (hospital perspective); an incidence of 10.5 would lead to costs ≥$30.6 million. Our model suggests that the annual US economic burden of CDI would be ≥$496 million (hospital perspective), ≥$547 million (third-party payer perspective) and ≥$796 million (societal perspective). Our results show that C. difficile infection is indeed costly, not only to third-party payers and the hospital, but to society as well. These results are consistent with current literature citing C. difficile as a costly disease.

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 ecology and pathobiology of Clostridium difficile infections: an interdisciplinary challenge

Clostridium difficile is a well recognized pathogen of humans and animals. Although C. difficile was first identified over 70 years ago, much remains unknown in regards to the primary source of human acquisition and its pathobiology. These deficits in our knowledge have been intensified by dramatic increases in both the frequency and severity of disease in humans over the last decade. The changes in C. difficile epidemiology might be due to the emergence of a hypervirulent stain of C. difficile, ageing of the population, altered risk of developing infection with newer medications, and/or increased exposure to C. difficile outside of hospitals. In recent years, there have been numerous reports documenting C. difficile contamination of various foods, and reports of similarities between strains that infect animals and strains that infect humans as well. The purposes of this review are to highlight the many challenges to diagnosing, treating, and preventing C. difficile infection in humans, and to stress that collaboration between human and veterinary researchers is needed to control this pathogen.

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

BACKGROUND/AIMS

The incidence of treatment failure or recurrence of Clostridium difficile-associated diarrhea (CDAD) following metronidazole treatment has increased recently. We studied the treatment failure, recurrence rate, and risk factors predictive of treatment failure and recurrence after metronidazole treatment for CDAD.

METHODS

We retrospectively identified consecutive patients who were admitted and treated for CDAD at a single tertiary institution in Korea over a recent 10-year period (i.e., 1998-2008).

RESULTS

Metronidazole was administered as the initial treatment to 111 of 117 patients (94.9%) with CDAD. Fourteen patients (12.6%) had no clinical response to the metronidazole treatment, and in 13 patients (13.4%) CDAD recurred after successful metronidazole treatment. Diabetes mellitus (p=0.014) and sepsis (p=0.002) were independent risk factors for metronidazole treatment failure. Patients who had received surgery within 1 month before CDAD developed were more likely to experience a recurrence after metronidazole treatment (p=0.032). Vancomycin exhibited a higher response rate after treatment failure, and metronidazole showed a reasonable response rate in the treatment of recurrence. Treatment failure and recurrence rates increased with time after metronidazole treatment for CDAD over the 10-year study period.

CONCLUSIONS

Our data suggest that diabetes mellitus and sepsis are independent risk factors for metronidazole treatment failure, and that operation history within 1 month of development of CDAD is a predictor of a recurrence after metronidazole treatment.

The enterotoxicity of Clostridium difficile toxins

The major virulence factors of Clostridium difficile infection (CDI) are two large exotoxins A (TcdA) and B (TcdB). However, our understanding of the specific roles of these toxins in CDI is still evolving. It is now accepted that both toxins are enterotoxic and proinflammatory in the human intestine. Both purified TcdA and TcdB are capable of inducing the pathophysiology of CDI, although most studies have focused on TcdA. C. difficile toxins exert a wide array of biological activities by acting directly on intestinal epithelial cells. Alternatively, the toxins may target immune cells and neurons once the intestinal epithelial barrier is disrupted. The toxins may also act indirectly by stimulating cells to produce chemokines, proinflammatory cytokines, neuropeptides and other neuroimmune signals. This review considers the mechanisms of TcdA- and TcdB-induced enterotoxicity, and recent developments in this field.

Clostridium difficile infection in Polish pediatric outpatients with inflammatory bowel disease

The prevalence of Clostridium difficile infection (CDI) in pediatric patients with inflammatory bowel disease (IBD) is still not sufficiently recognized. We assessed the prevalence of CDI and recurrences in outpatients with IBD. In addition, the influence of IBD therapy on CDI and antimicrobial susceptibility of the potentially causative C. difficile strains was assessed. This was a prospective, single-center, observational study. All specimens were obtained between January 2005 and January 2007 from the IBD outpatient service and screened for C. difficile and its toxins. C. difficile isolates were genotyped by PCR ribotyping. Diagnosis of Crohn’s disease (CD) and ulcerative colitis (UC) was based on Porto criteria. Severity of disease was assessed using the Hyams scale (for Crohn’s disease) and the Truelove–Witts scale (for ulcerative colitis). One hundred and forty-three fecal samples from 58 pediatric IBD patients (21 with Crohn’s disease and 37 with ulcerative colitis) were screened. The risk of C. difficile infection was 60% and was independent of disease type (CD or UC) (χ2 = 2.5821, df = 3, p = 0.4606). About 17% of pediatric IBD patients experienced a recurrence of CDI. All C. difficile strains were susceptible to metronidazole, vancomycin and rifampin. A high prevalence of C. difficile infection and recurrences in pediatric outpatients with IBD was observed, independent of disease type. There was no significant correlation between C. difficile infection and IBD therapy. PCR ribotyping revealed C. difficile re-infection and relapses during episodes of IBD in pediatric outpatients.

The potential value of Clostridium difficile vaccine: an economic computer simulation model

Efforts are currently underway to develop a vaccine against Clostridium difficile infection (CDI). We developed two decision analytic Monte Carlo computer simulation models: (1) an Initial Prevention Model depicting the decision whether to administer C. difficile vaccine to patients at-risk for CDI and (2) a Recurrence Prevention Model depicting the decision whether to administer C. difficile vaccine to prevent CDI recurrence. Our results suggest that a C. difficile vaccine could be cost-effective over a wide range of C. difficile risk, vaccine costs, and vaccine efficacies especially, when being used post-CDI treatment to prevent recurrent disease.

Clinical predictors and risk factors for relapsing Clostridium difficile infection

BACKGROUND

Clostridium difficile infection (CDI) is a common cause of morbidity among hospitalized patients. Multiple factors have been associated with primary CDI, but risk factors for CDI relapses are less well described.

METHODS

This was a retrospective cohort study of patients with CDI over a 15-month period. We compared patients with relapsing and nonrelapsing CDI, including risk factors associated with primary CDI and other variables hypothesized to be associated with relapsing CDI and 90-day mortality. Multivariable logistic regression models were created to examine risk factors for relapse and 90-day mortality.

RESULTS

One hundred twenty-nine consecutive patients with CDI were included; 38 (29%) had relapsing CDI. Factors associated with relapsing CDI included fluoroquinolone use (71% versus 49%, P = 0.04) and incidence of stroke (29% versus 12%, P = 0.02). In a regression model, use of a fluoroquinolone was associated with relapsing CDI (OR = 2.52, 95% CI = 1.11-5.72). Factors associated with 90-day mortality included higher Charlson comorbidity index score (4.34 +/- 1.71 versus 3.42 +/- 2.08, P = 0.02), severe CDI (58% versus 32%, P = 0.01), and the use of piperacillin/tazobactam (45% versus 23%, P = 0.03) or meropenem (10% versus 1%, P = 0.04). In the regression analysis, 90-day mortality was associated with severe CDI (OR = 1.76; 95% CI = 1.19-2.59).

CONCLUSION

Fluoroquinolone use and prior stroke are associated with an increased risk of relapsing CDI. Relapsing CDI and severe CDI are both associated with increased 90-day mortality.

Clostridium difficile and the disease it causes

Clostridium difficile is a spore-forming, toxin-producing, anaerobic bacterium abundant in soils and water. Frequent and early colonization of the human intestinal flora is common and often asymptomatic. Antimicrobials given commonly disrupt the intestinal microflora and through proliferation in colon and production of toxin A and B it precipitates C. difficile infection (CDI). The enterocytic detachment and bowel inflammation provoke C. difficile-associated diarrhoea (CDAD) sometimes developing into severe pseudomembranous colitis (PMC) and paralytic ileus. Infection is acquired from an endogenous source or from spores in the environment, most easily facilitated during hospital stay. In the elderly, comorbidity, hospitalization and antimicrobial treatment present as major risk factors and the slow recolonization of the normal flora likely responsible for single or multiple recurrences of CDI (25-50%) post therapy. The key procedure for diagnosis is toxin detection from stool specimens and sometimes in combination with culture to increase sensitivity. In mild cases stopping the offending antimicrobial will lead to resolution (25%) but standard therapy still consist of either oral metronidazole or vancomycin. Alternative agents are presently being developed and fidaxomicin, as well as nitrothiazolide are promising. Furthermore, host factors like low antitoxin A levels in serum relates to increased risk of recurrence and small numbers of patients have received immunoglobulin with good results. An immunogenic toxoid vaccine has been developed and human colostrum rich in specific secretory Ig A also support the future use of immunotherapy. Today we experience a tenfold increase of CDI incidence in the western world and both epidemics and therapeutic failure of metronidazole is contributing to morbidity and mortality. The current epidemic of the C. difficile strain NAP1/027 emerging in 2002 in Canada and the USA has now spread to most parts of Europe and virulence factors like high toxin production and sporulation challenge the therapeutic situation and cause great concern among infection control workers. Excessive use of modern fluoroquinolones is thought to play an important role in facilitating this epidemic since NAP1/027 was shown to have acquired moxifloxacin resistance compared to historical strains of the same genotype. Both the current epidemic like this and other local outbreaks from resistant or virulent strains warrant culture to be routinely performed enabling susceptibility testing and typing of the pathogen. Genotyping is most commonly done today by pulse-field gel electrophoresis (PFGE) or PCR ribotyping but multilocus variable-number tandem-repeat analysis (MLVA) seems promising. Epidemiological surveillance using all these tools will help us to better understand the global spread of C. difficile.

Clostridium difficile in solid organ transplant recipients

Clostridium difficile infection (CDI) is a common problem encountered in solid organ transplant (SOT) recipients and the incidence is increasing. Generally, SOT recipients have an incidence of CDI that is similar to other post-operative patients, but this group has several unique risk factors that may contribute to more severe disease. Recent studies in non-transplant patients have indicated that treatment choices should be based on the severity of the illness. Although there continues to be a lack of well designed, randomized, controlled trials to support the management decisions that must be made for SOT recipients with CDI, the available evidence is reviewed and summarized for these treatment guidelines.

[Comparison of three Clostridium difficile culture media: interest of enhancing spore germination media?]

AIM

Clostridium difficile is the most common agent of postantibiotic and nosocomial bacterial diarrhoea. Since the emergence of the highly virulent and epidemic strain NAP1/027 in Europe, it appears necessary to isolate C. difficile strains to realize an epidemiologic follow-up by molecular typing. The aim of this work was to compare three selective culture conditions for the isolation of C. difficile.

METHODS

One hundred and thirty stools collected from patients hospitalized at Jean Verdier were swabbed on the commercial medium CLO (BioMérieux) and on a medium prepared at the laboratory (CCTa: Columbia, cefoxitine 8 mg/l, cycloserine 250 mg/l, horse blood 5 %, sodium taurocholate 0.1 %) with and without preliminary alcoholic shock (EtOH). C. difficile was isolated from 38 stools and colonies were counted on each medium.

RESULTS

The fluorescence intensity of C. difficile colonies is comparable on CLO and CCTa-EtOH media, however their aspect is more characteristic on CLO. This medium appears very selective contrary to the CCTa medium on which an associated flora obstructs the fluorescence reading and requires a new isolation of the suspect strains. On average 30 times more colonies of C. difficile are counted on CCTa+/-EtOH than on CLO, suggesting the presence of great proportions of spores in the stools.

CONCLUSIONS

The medium CLO is successful for the isolation of C. difficile despite of its selectivity. Nevertheless, it appears interesting to associate a medium enhancing spore germination as the CCTa medium inoculated after alcoholic shock to increase the sensitivity of detection while being freed from conservation and transport conditions.

Clostridium difficile infection in the intensive care unit

Clostridium difficile infection (CDI) is becoming more common worldwide. The morbidity and mortality associated with C difficile is also increasing at an alarming rate. Critically ill patients are at particularly high risk for CDI because of the prevalence of multiple risk factors in this patient population. Treatment of C difficile continues to be a difficult problem in patients with severe or recurrent disease. This article seeks to provide a broad understanding of CDI in the intensive care unit, with special emphasis on risk factor identification, treatment options, and disease prevention.

Recurrent Clostridium difficile infection: causality and therapeutic approaches

Recurrent diarrhoea after successful treatment of the primary episode is a common complication of Clostridium difficile infection (CDI) and may be increasing in frequency. Evidence suggests that persistent alterations in the indigenous bowel flora and failure to mount an effective antibody response to C. difficile toxins are the main mechanisms whereby recurrent CDIs occur. Treatment of the first recurrence with the same agent used for the treatment of the primary episode is reasonable, but a different approach is needed for patients with multiple CDI recurrences. Prolonged, repeated courses of metronidazole are discouraged, but a practical first option in these patients is to use tapered-dose oral vancomycin followed by a pulsed-dose regimen. Other potential options include probiotic approaches, restoration of the normal flora, immunological approaches, toxin-binding approaches, and serial therapy with vancomycin followed by rifaximin. Randomised studies including a sufficient numbers of patients have not yet been conducted for the treatment of recurrent CDI and are needed to help guide the formulation of effective recommendations.

Clostridium difficile colitis

Clostridium difficile is the most common cause of infectious diarrhea in hospitalized patients. Its effects are mediated by C difficile toxins A and B. Recent outbreaks of severe colitis have been associated with a new strain of the bacterium that produces large amounts of the toxins. Although oral metronidazole and oral vancomycin can be used to treat C difficile-associated disease, intraluminal vancomycin is preferable for more severe C difficile colitis. Early surgical intervention can improve outcomes with fulminant colitis, although overall mortality remains high.

Clostridium difficile infection in solid organ transplant recipients

PURPOSE OF REVIEW

To provide a general understanding of Clostridium difficile infection with a focus on recent publications that evaluate the disease in solid organ transplant recipients.

RECENT FINDINGS

The incidence of C. difficile infection is increasing worldwide. Epidemics due to a hypervirulent C. difficile strain are associated with an escalating severity of disease. New evidence further supports basing initial treatment choice on disease severity.

SUMMARY

C. difficile is a significant pathogen in solid organ transplant recipients. Multiple risk factors are found in this population that may result in more severe disease. A high index of suspicion is necessary for the early diagnosis and treatment of C. difficile infection in transplant recipients. Metronidazole and vancomycin show equivalent efficacy in the treatment for mild-to-moderate disease, but vancomycin has demonstrated superiority in the treatment of severe disease. Surgical intervention is also an important consideration in the treatment of solid organ transplant recipients with severe colitis. Rigorous infection control practices are essential for preventing the spread of C. difficile within the hospital environment.

Comparison of molecular typing methods applied to Clostridium difficile

Since the 1980s the epidemiology of Clostridium difficile infection (CDI) has been investigated by the application of many different typing or fingerprinting methods. To study the epidemiology of CDI, a typing method with a high discriminatory power, typeability, and reproducibility is required. Molecular typing methods are generally regarded as having advantages over phenotypic methods in terms of the stability of genomic markers and providing greater levels of typeability. A growing number of molecular methods have been applied to C. difficile. For the early and rapid detection of outbreak situations, methods such as restriction enzyme analysis, arbitrary primed polymerase chain reaction (PCR), and PCR ribotyping are commonly used. For long-term epidemiology, multilocus sequence typing, multilocus variable number of tandem repeats analysis, and amplified fragment length polymorphism are of interest. Currently, the PCR-ribotyping method and the library of PCR ribotypes in Cardiff are the benchmarks to which most typing studies around the world are compared. Multilocus variable number of tandem repeats analysis is the most discriminative typing method and will contribute significantly to our understanding of the epidemiology of this important nosocomial pathogen.

Clostridium difficile in broiler chickens sold at market places in Zimbabwe and their antimicrobial susceptibility

Clostridium difficile has been shown to be a nosocomial pathogen associated with diarrhoea and pseudomembranous colitis in hospitalised patients and the infection is believed to be acquired nosocomially. Community-acquired C. difficile-associated diarrhoea has also been reported. Recent studies have shown the occurrence of C. difficile in food animals which may act as a source of infection to humans. The aim of this study was to determine the occurrence of C. difficile in broiler chickens sold at market places in an urban area in Zimbabwe. Faeces of broiler chickens were collected from the cages at the market places and soils were collected from areas around the market places. The chicken faeces and soil samples were cultured for C. difficile. The C. difficile isolates were tested for toxins A or B production as well as for their susceptibility to antimicrobial drugs. C. difficile was isolated from 29.0% of 100 chicken faeces samples and 22.0% of 100 soil samples. Some of the C. difficile isolates from chickens (89.7%) and soils (95.5%) were toxigenic. All the isolates were susceptible to metronidazole, vancomycin, doxycycline, chloramphenicol and tetracycline. Over 70% of the isolates were susceptible to erythromycin, co-trimoxazole and ampicillin. They were all resistant to cefotaxime, gentamicin, ciprofloxacin, norfloxacin and nalidixic acid. The results of the present study suggest that broiler chickens sold at market places in the urban area are an important source of C. difficile, which may infect humans through consumption of chicken meat.

The changing spectrum of clostridium difficile associated disease: implications for dentistry

BACKGROUND

Clostridium difficile is an anaerobic, spore-forming bacterium that causes a wide range of diseases of the gastrointestinal tract. It is best known for its association with uncomplicated antimicrobial-agent-associated diarrhea.

CASE DESCRIPTION

The authors describe two previously published cases of Clostridium difficile-associated disease (CDAD) to highlight its varied clinical manifestations. A 48-year-old woman had mild CDAD after receiving antibiotics after undergoing endodontic surgery. She took metronidazole, and her C. difficile infection resolved. A 31-year-old pregnant woman developed severe CDAD after receiving antibiotics for a urinary tract infection. She underwent surgery to remove part of her colon, but her condition worsened, and she died.

CLINICAL IMPLICATIONS

Dentists often prescribe antimicrobial agents to treat infections. Until recently, these agents also were recommended as prophylaxis for infective endocarditis during invasive oral procedures. An important risk factor for CDAD and recurrent CDAD is antimicrobial agent exposure. Dentists should be aware of CDAD to help prevent its spread and facilitate early recognition and treatment to minimize severe outcomes.

Diagnostic and treatment delays in recurrent Clostridium difficile-associated disease

BACKGROUND

Because Clostridium difficile-associated disease (CDAD) is primarily an inpatient issue, hospitalists are at the forefront of the timely diagnosis and treatment of patients with this disease.

DESIGN

The study was a retrospective cohort of all inpatients with CDAD at Brigham and Women's Hospital from 1997 to 2004 in order to determine the time to diagnosis and treatment in initial and recurrent episodes of disease.

RESULTS

The mean time to sampling, between 2.09 and 2.24 days, was not significantly different between initial and recurrent CDAD hospital episodes. The mean time to treatment (from symptoms and sampling) was shorter in recurrent episodes but was still 2.5 days.

CONCLUSIONS

Patients with recurrent disease were more likely to be treated earlier but not diagnosed earlier than those with initial disease. Because both groups had significant diagnostic and treatment delays, this is an area in which hospitalists can have a major impact on patient care.

Treatment of Clostridium difficile infection

Recent outbreaks of Clostridium difficile infection (CDI) in North America have been due to a more virulent, possibly more resistant strain that causes more-severe disease, making prompt recognition of cases and optimal management of infection essential for a successful therapeutic outcome. Treatment algorithms are presented to help guide the management of patients with CDI. Metronidazole has been recommended as initial therapy since the late 1990s and continues to be the first choice for all but seriously ill patients and those with complicated or fulminant infections or multiple recurrences of CDI, for whom vancomycin is recommended. Other options for recurrent CDI, such as probiotics and currently available anion-exchange resins, have limited efficacy and are potentially harmful. Intravenous immunoglobulin may benefit patients with refractory, recurrent, or severe disease, but no controlled data are available. Two antimicrobials available in the United States for other indications, nitazoxanide and rifaximin, have been used successfully for CDI treatment but, like metronidazole, lack United States Food and Drug Administration approval for this indication. Experimental treatments currently in clinical development include a toxin-binding polymer, tolevamer; 2 poorly absorbed antimicrobials, OPT-80 (formerly known as Difimicin) and ramoplanin; monoclonal antibodies; and a C. difficile vaccine.

Diarrheal diseases in the elderly

Diarrhea in the elderly population is one disease that needs special attention in treatment and management, especially in acute- and long-term care residents, because of their multiple comorbidities, immunosenescence, frailty, and poor nutritional status. Close follow-up to ensure adequate hydration and electrolyte replacement and infection control measures to contain outbreaks should be emphasized to caregivers and nursing staff in acute- and long-term care facilities. Although C difficile colitis causes significant morbidity and mortality in this population, judicious use of antibiotics is important to decrease the incidence and recurrence of the disease. When the diarrhea is chronic and all stool testings and serologies have been performed, the patient may benefit from endoscopy and colonoscopy for biopsy. Attentive and vigilant nursing staff is crucial in the timely diagnosis and treatment of diarrheal diseases to improve quality of life and reduce mortality.

Bench-to-bedside review: Clostridium difficile colitis

In recent years, the incidence and severity of Clostridium difficile-associated disease (CDAD) have increased dramatically. Beginning in 2000, widespread regional outbreaks associated with a previously uncommon hypervirulent strain of C. difficile have occurred in North America and Europe. Most likely because of increased toxin production as well as other virulence factors, this epidemic strain has caused more severe and refractory disease leading to complications, including intensive care unit admission, colectomies, and death. Worldwide increasing use of fluoroquinolones and cephalosporins has likely contributed to the proliferation of this epidemic strain, which is highly resistant to both. The elderly have been disproportionately affected by CDAD, but C. difficile has also recently emerged in populations previously considered to be at low risk, including healthy outpatients and peripartum women, although it is unknown if these cases are related to the epidemic strain. Nevertheless, transmission within hospitals is the major source of C. difficile acquisition, and previous or concurrent antimicrobial use is almost universal among cases. Applying current evidence-based strategies for management and prevention is critically important, and clinicians should maintain an awareness of the changing epidemiology of CDAD and take measures to reduce the risk of disease in patients.

Infections in residents of nursing homes

Infectious diseases are a very common occurrence in nursing homes. While the reasons for preventing infections are the same in nursing homes and in acute hospitals, several considerations relevant to prevention of infection differ in nursing homes. Infection control measures should be based upon the particularities of the specific setting of a nursing home and its residents.