Comparison of three enzyme immunoassays, a cytotoxicity assay, and toxigenic culture for diagnosis of Clostridium difficile-associated diarrhea

Isolation and characterization of a multidrug-resistant Clostridioides difficile toxinotype V from municipal wastewater treatment plant

PURPOSE

Wastewater treatment plant (WWTP) is regarded as a potential source for transmission of Clostridioides difficile from urban areas into the surface water, through feces of human and animals. The aim of this study was to screen and characterize the C. difficile bacteria in inlet and outlet wastewater of different WWTPs in Tehran, Iran.

METHODS

Totally, 72 samples were collected from three different WWTPs (inlet site and outlet sites) during a year. C. difficile was isolated and characterized in terms of toxins, toxinotype, resistance profile and genes, and colonization factors using PCR.

RESULTS

One C. difficile toxinotype V was isolated from the outlet samples. The isolate was susceptible to vancomycin but resistant to metronidazole, tetracycline, ciprofloxacin, and moxifloxacin using MIC Test Strips. The isolated C. difficile was toxigenic (tcdA, tcdB, cdtA, cdtB positive and CPE positive) and had tcdC-A genotype. No mutations were found in fliC and fliD. The slpA sequence type was 078 - 01. The C. difficile was positive for tetM, int, but negative for vanA, nim, and tndX genes. Mutations were not observed in gyrA and gyrB genes.

CONCLUSIONS

This study provided evidence of presence of a multidrug-resistant C. difficile toxinotype V in one of the municipal WWTP. The transmission of such isolate to the environment and reuse of treated wastewater by human pose a threat to human health and dissemination of antibiotic resistant bacteria which are untreatable.

Evaluation of inpatients Clostridium difficile prevalence and risk factors in Cameroon

BACKGROUND

Clostridium difficile, rarely found in hospitals, is a bacterium responsible for post-antibiotic diarrhea and Pseudomembranous Colitis (CPM). C. difficile selective pressure represents potential public health problem due to the production of toxins A and B serious pathologies effects/consequences. A transversal and analytic study was to assess the risk factors of C. difficile infection and to determine the prevalence of C. difficile in patients received in randomly selected five hospitals in Yaoundé, Cameroon.

METHODS

A total of 300 stool samples were collected from consented patients using a transversal and analytic study conducted from 10th July to 10th November 2018 in five hospitals in Cameroon. The detection or diagnostic kit was CerTest C. difficile Glutamate Dehydrogenase + Toxin A + Toxin B based on immuno-chromatographic assay. A univariate and multivariate analysis allowed us to highlight the associated factors.

RESULTS

The results showed a prevalence of C. difficile of 27.33% (82/300 stool patients'samples taken). Of these 27.33%, the production of Toxin A and Toxin B were 37.80 and 7.31% respectively. In univariate analysis, hospitalization was a significant (P = 0.01) risk factor favoring C. difficile infection. In multivariate analysis, corticosteroids and quinolones use/administration were significantly (adjusted Odd Ratio, aOR = 14.09, 95% CI: 1.62-122.54, P = 0.02 and aOR = 3.39, 95% CI: 1.00-11.34, P = 0.05 respectively) risk factor for this infection.

CONCLUSION

The prevalence of C. difficile infections (CDI) remain high in these settings and may be related not only to permanent steroids and antibiotics. Promoting education to both medical staff and patients on the prevalence and public health impact of C. difficile can be core inimproving rationale prescription of steroids and antibiotics to patients and promote human health and exponential growth in Cameroon.

Enterotoxic Clostridia: Clostridioides difficile Infections

Clostridioides difficile is a Gram-positive, anaerobic, spore forming pathogen of both humans and animals and is the most common identifiable infectious agent of nosocomial antibiotic-associated diarrhea. Infection can occur following the ingestion and germination of spores, often concurrently with a disruption to the gastrointestinal microbiota, with the resulting disease presenting as a spectrum, ranging from mild and self-limiting diarrhea to severe diarrhea that may progress to life-threating syndromes that include toxic megacolon and pseudomembranous colitis. Disease is induced through the activity of the C. difficile toxins TcdA and TcdB, both of which disrupt the Rho family of GTPases in host cells, causing cell rounding and death and leading to fluid loss and diarrhea. These toxins, despite their functional and structural similarity, do not contribute to disease equally. C. difficile infection (CDI) is made more complex by a high level of strain diversity and the emergence of epidemic strains, including ribotype 027-strains which induce more severe disease in patients. With the changing epidemiology of CDI, our understanding of C. difficile disease, diagnosis, and pathogenesis continues to evolve. This article provides an overview of the current diagnostic tests available for CDI, strain typing, the major toxins C. difficile produces and their mode of action, the host immune response to each toxin and during infection, animal models of disease, and the current treatment and prevention strategies for CDI.

Highly antibiotic-resistant Clostridium difficile isolates from Iranian patients

AIMS

Little is known about the resistance rate and susceptibility profile of Clostridium difficile isolates in Iran. Therefore, the aim of present study is to assess the rate of drug-resistant C. difficile.

METHODS AND RESULTS

During a 6-year period, four hospitals submitted 735 stool specimens from patients suspected for C. difficile infections to the anaerobic bacteriology laboratory. The 46 C. difficile isolates were subjected to disc diffusion and minimum inhibitory concentration (MIC) Test Strips. All isolates were susceptible to vancomycin (VAN) while the highly resistant phenotypes of metronidazole (MTZ) (67·4%), moxifloxacin (78·3%), ciprofloxacin (69·5%) and tetracycline (82·6%) were observed. Of more concern, 67·3% of C. difficile isolates displayed multidrug-resistant phenotypes. More than half of the isolates (n = 27, 58·6%) were coresistant to ciprofloxacin and moxifloxacin. The MIC90 of VAN was ≤2 mg l^-1 , whereas this value for MTZ, ciprofloxacin, moxifloxacin and tetracycline was higher than the resistance breakpoints. According to the comparison of interpretive categories for two tests, the categorical agreement was less than 90% for VAN, ciprofloxacin and tetracycline.

CONCLUSIONS

The disc diffusion method can be used to detect the isolates with reduced susceptibility to MTZ or moxifloxacin. The high rate of resistance to fluoroquinolones highlights the possibility of the emergence of hypervirulent strains in our settings.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides data regarding the high level of resistance against multiple antibiotics except VAN.

Pathogenicity locus determinants and toxinotyping of Clostridioides difficile isolates recovered from Iranian patients

Little is known about the toxin profiles, toxinotypes and variations of toxin Clostridioides difficile C (tcdC) in Iranian C. difficile isolates. A total of 818 stool specimens were obtained from outpatients (n = 45) and hospitalized patients (n = 773) in Tehran, Iran, from 2011 to 2017. The 44 C. difficile isolates were subjected to PCR of toxin C. difficile A (tcdA), toxin C. difficile B (tcdB), tcdA 3′-end deletion, toxinotyping and sequencing of the tcdC gene. Thirty-eight isolates (86.36%) were identified as tcdA and tcdB positive, and the remaining six isolates (13.63%) were nontoxigenic. All tcdA- and tcdB-positive isolates yielded an amplicon of 2535 bp by PCR for the tcdA 3′ end. Fourteen (36.84%), seventeen (44.73%) and seven (18.43%) isolates belonged to wild-type, toxin C. difficile C subclone3 (tcdC-sc3) and tcdC-A genotype of tcdC, respectively. Thirty-one isolates (81.57%) belonged to toxinotype 0, and seven isolates (18.42%) were classified as toxinotype V. This study provides evidence for the circulation of historical and hypervirulent isolates in the healthcare and community settings. Furthermore, it was also demonstrated that the tcdC-A genotype and toxinotype V are not uncommon among Iranian C. difficile isolates.

The Differential Diagnosis of Acute Colitis: Clues to a Specific Diagnosis

This review describes a systematic approach to the interpretation of colonic biopsy specimens of patients with acute colitis. Five main histologic patterns are discussed: acute colitis, focal active colitis, pseudomembranous colitis, hemorrhagic colitis, and ischemic colitis. For each pattern, the most common etiologic associations and their differential diagnoses are presented. Strategies based on histologic analysis and clinical considerations to differentiate acute from chronic colitides are discussed.

Optimizing the diagnostic testing of Clostridium difficile infection

INTRODUCTION

Clostridium difficile infection (CDI) is the leading cause of hospital-acquired diarrhea and is associated with a considerable health and cost burden. However, there is still not a clear consensus on the best laboratory diagnosis approach and a wide variation of testing methods and strategies can be encountered.

AREAS COVERED

We aim to review the most practical aspects of CDI diagnosis providing our own view on how to optimize CDI diagnosis. Expert commentary: Laboratory diagnosis in search of C. difficile toxins should be applied to all fecal diarrheic samples reaching the microbiology laboratory in patients > 2 years old, with or without classic risk factors for CDI. Detection of toxins either directly in the fecal sample or in the bacteria isolated in culture confirm CDI in the proper clinical setting. Nuclear Acid Assay techniques (NAAT) allow to speed up the process with epidemiological and therapeutic consequences.

Evaluation of Five Enzyme Immunoassays Compared with the Cytotoxicity Assay for Diagnosis of Clostridium Difficile-Associated Diarrhea in Dogs

Clostridium difficile-associated-diarrhea (CDAD) is a nosocomial infection in dogs. Diagnosis of this infection is dependent on clinical signs of disease supported by laboratory detection of C. difficile toxins A or B, or both, in fecal specimens via enzyme-linked immunosorbent assay (ELISA). Unfortunately, to the authors' knowledge, commercially available ELISAs have not been validated in dogs to date. We evaluated 5 ELISAs done on 143 canine fecal specimens (100 diarrheic and 43 nondiarrheic dogs) and on 29 C. difficile isolates. The results of each ELISA were compared with the cytotoxin B tissue culture assay (CTA). Clostridium difficile was isolated from 23% of the fecal specimens. Eighteen of the 143 fecal specimens were toxin positive (15 diarrheic and 3 nondiarrheic dogs). On the basis of multiplex polymerase chain reaction (PCR) analysis for toxin-A and -B genes, 72% of the isolates were toxigenic. The carriage rate of toxigenic isolates in diarrheic dogs was higher than that in the nondiarrheic dogs; however, these differences were not statistically significant. A good correlation was found between CTA, PCR, and culture results. The ELISAs done on fecal specimens collected from diarrheic dogs had low sensitivity (7–33%). In contrast, ELISA for toxin A or B, or both, performed on toxigenic isolates had high sensitivity (93%). These results suggest that commercially available human ELISAs are inadequate for the diagnosis of canine C. difficile-associated diarrhea when tested on fecal specimens. In contrast, the Premier ToxinA/B and Techlab ToxinA/B ELISAs may be useful for the diagnosis of canine CDAD when used on toxigenic isolates.

Similar proportions of stool specimens from hospitalized children with and without diarrhea test positive for Clostridium difficile

BACKGROUND

Many laboratories use polymerase chain reaction (PCR)-based assays to detect the Clostridium difficile toxin B gene (tcdB) in stool. However, PCR testing experience in pediatric patients is limited. We compared the detection of C. difficile by PCR in hospitalized children with and without diarrhea.

METHODS

Stool samples from patients aged 1-18 years with diarrhea (symptomatic) and from patients without diarrhea (asymptomatic) were tested for C. difficile tcdB using a commercial PCR assay. Samples were cultured for C. difficile using standard techniques with tcdB PCR and cytotoxicity assays performed on C. difficile isolates. Demographic, clinical and laboratory data were abstracted. Categorical and continuous variables were compared between the 2 groups using Fisher Exact test and the Mann-Whitney test, respectively.

RESULTS

Thirty-five of 188 (19%) stool samples from symptomatic patients and 18 of 74 (24%) samples from asymptomatic patients were positive by PCR (P=0.31). Among PCR-positive patients, symptomatic patients had a significantly higher proportion of subjects who received antimicrobials in the preceding 30 days (P=0.04) and a greater number of preceding antimicrobial days than did asymptomatic patients (P=0.02) but were comparable with respect to the other variables analyzed.

CONCLUSIONS

C. difficile PCR assays are frequently positive in hospitalized children both with and without diarrhea. As we observed a high level of toxigenic C. difficile colonization in children, our findings suggest that a positive C. difficile PCR result in a child with diarrhea should be interpreted with caution.

Hyperimmune bovine colostrum as a novel therapy to combat Clostridium difficile infection

BACKGROUND

Clostridium difficile is a primary cause of antibiotic-associated diarrhea that typically develops when gut microbiota is altered. Conventional treatment for C. difficile infection (CDI) is additional antimicrobial administration, which further disrupts normal intestinal microbiota, often resulting in poor treatment outcomes.

METHODS

A pregnant dairy cow was repeatedly immunized with recombinant mutants of toxins A and B produced by C. difficile, and the resultant hyperimmune bovine colostrum (HBC) was evaluated for therapeutic efficacy in gnotobiotic piglets with diarrhea due to CDI. Control piglets received nonimmune colostrum. To determine the impact of HBC on gut microbiota, 1 of 2 groups of piglets transplanted with normal human gut microbiota was treated with HBC.

RESULTS

Nonimmune colostrum-treated piglets developed moderate to severe diarrhea and colitis. In contrast, HBC-treated piglets had mild or no diarrhea and mild or no colitis. Lyophilization had no detectable impact on HBC efficacy. HBC had no discernible effect on the composition of normal human gut microbiota in the porcine intestinal tract.

CONCLUSIONS

HBC provides an oral, cost-effective, and safe alternative to antibiotic therapy for CDI. By preserving intestinal microbiota, HBC may be more efficacious than antibiotics. Additional studies are warranted to establish HBC as a viable immunotherapeutic agent for human use against CDI.

Clostridium difficile infection in diabetes

Diabetes-related hospitalization and hospital utilization is a serious challenge to the health care system, a situation which may be further aggravated by nosocomial Clostridium difficile (C. difficile) infection (CDI). Studies have demonstrated that diabetes increases the risk of recurrent CDI with OR (95% CI) 2.99 (1.88, 4.76). C. difficile is a gram-positive, spore-forming anaerobic bacterium which is widely distributed in the environment. Up to 7% of healthy adults and up to 45% of infants may have asymptomatic intestinal carriage of C. difficile. A large number of strains of C. difficile have been identified. A number of PCR or sequence-based molecular typing methods are available for typing C. difficile isolates. C. difficile virulence evolved independently in the highly epidemic lineages, associated with the expression of toxin genes and other virulence factors. This article briefly reviews recent progresses in the bateriology of C. difficile and highlights the limited knowledge of potential mechanisms for the increased risk of CDI in diabetes which warrants further research.

Healthcare resource utilization for recurrent Clostridium difficile infection in a large university hospital in Houston, Texas

Background

There are limited data examining healthcare resource utilization in patients with recurrent Clostridium difficile infection (CDI).

Methods

Patients with CDI at a tertiary-care hospital in Houston, TX, were prospectively enrolled into an observational cohort study. Recurrence was assessed via follow-up phone calls. Patients with one or more recurrence were included in this study. The location at which healthcare was obtained by patients with recurrent CDI was identified along with hospital length of stay. CDI-attributable readmissions, defined as a positive toxin test within 48 hours of admission and a primary CDI diagnosis, were also assessed.

Results

372 primary cases of CDI were identified of whom 64 (17.2%) experienced at least one CDI recurrence. Twelve of 64 patients experienced 18 further episodes of CDI recurrence. Of these 64 patients, 33 (50.8%) patients with recurrent CDI were readmitted of which 6 (18.2%) required ICU care, 29 (45.3%) had outpatient care only, and 2 (3.1%) had an ED visit. Nineteen (55.9%) readmissions were defined as CDI-attributable. For patients with CDI-attributable readmission, the average length of stay was 6±6 days.

Conclusion

Recurrent CDI leads to significant healthcare resource utilization. Methods of reducing the burden of recurrent CDI should be further studied.

Assessment of treatment patterns and patient outcomes before vs after implementation of a severity-based Clostridium difficile infection treatment policy

BACKGROUND

National guidelines recommend oral vancomycin for severe Clostridium difficile infection (CDI) based on results from recent clinical trials demonstrating improved clinical outcomes. However, real-world data to support these clinical trials are scant.

AIM

To compare treatment patterns and patient outcomes of those treated for CDI before and after implementation of a severity-based CDI treatment policy at a tertiary teaching hospital.

METHODS

This study evaluated adult patients with a positive C. difficile toxin before and after implementation of a policy where patients with severe CDI given metronidazole were switched to oral vancomycin unless contra-indicated. Patients were stratified according to disease severity using a modified published severity score. Treatment patterns based on CDI severity and rates of refractory CDI were assessed.

FINDINGS

In total, 256 patients with CDI (mean age 66 years, standard deviation 17, 52% female) were evaluated (before implementation: N = 144; after implementation: N = 112). Use of oral vancomycin for severe CDI increased significantly from 14% (N = 8) to 91% (N = 48) following implementation of the policy (P < 0.0001). Refractory disease in patients with severe CDI decreased significantly from 37% to 15% following implementation of the policy (P = 0.035). No significant differences were noted among patients with mild to moderate CDI.

CONCLUSION

A severity-based CDI treatment policy at a tertiary teaching hospital increased the use of oral vancomycin and was associated with decreased rates of refractory CDI.

Clostridium difficile infection in the inflammatory bowel disease patient

Clostridium difficile infection (CDI) has been increasing in frequency and severity in patients with inflammatory bowel disease (IBD). Population based and single center studies have shown worse clinical outcomes in concomitant CDI and IBD, with several reporting longer length of hospital stay, higher colectomy rates and increased mortality. Clinically, CDI may be difficult to distinguish from an IBD flare and may range from an asymptomatic carrier state to severe life threatening colitis. The traditional risk factors for CDI have included hospitalization, antibiotic use, older age and severe co-morbid disease but IBD patients have several distinct characteristics including younger age, community acquisition, lack of antibiotic exposure, colonic IBD and steroid use. CDI can occur in the small bowel and specifically in ulcerative colitis patients who have had a colectomy and an ileal pouch anal anastomosis. PCR based assays and combination Elisa algorithms have improved the sensitivity and specificity of testing, though in IBD patients have raised clinical questions about how to best manage diarrhea in the setting of possible C. difficile colonization. Treatment modalities for CDI have not been examined in randomized clinical trials in the IBD population. Newer antibiotics, immunotherapy and fecal microbiota transplantation may alter current treatment strategies. This review will focus on the unique epidemiology of CDI in IBD patients, detail clinical disease states, and provide updated diagnostic strategies, prevention and treatment options.

Comparison of antigen and two molecular methods for the detection of Clostridium difficile toxins

BACKGROUND

Clostridium difficile (CD) is considered an important cause of diarrhoea associated with the antimicrobial treatment of infections. The pathogenicity of CD is due to toxins A and B, produced by toxigenic CD strains.

METHODS

We evaluated 3 methods for detecting CD toxins: the RIDASCREEN® enzyme immunoassay (EIA) (R-Biopharm)--one detecting toxins directly in the stool specimens and another detecting toxins from isolated CD strains--and 2 molecular methods, the illumigene™ loop-mediated isothermal amplification (LAMP) assay (Meridian) and RIDA®GENE polymerase chain reaction (PCR) assay (R-Biopharm), as direct identification methods from stool specimens. Toxigenic culture (TC) was used as the reference method.

RESULTS

Altogether 884 stool samples were analyzed, of which 253 (29%) were positive by TC. Six hundred and seventy-two specimens were tested by RIDASCREEN EIA, 430 were tested with the illumigene LAMP assay, and 212 were tested with the RIDA GENE PCR assay. CD toxin A and B antigen tests by EIA were very insensitive, both directly from stool specimens (2 series; 57-61%) and in isolated CD strains (53%); consequently the negative predictive value remained low (84-93% and 91%, respectively). Specificity, however, was very good at 98-100%. The 2 molecular methods detected CD toxin genes excellently and equally, resulting in sensitivities, specificities, and positive and negative predictive values of 98%, 100%, 100%, and 98%, respectively.

CONCLUSIONS

Both molecular assays were easy to use, rapid, sensitive, and specific for the detection of toxigenic CD strains.

Clostridium difficile Infections: What Every Clinician Should Know

The leading cause of nosocomial enteric infections in the US is a potentially lethal condition that influences the daily care of medical and surgical patients across all specialties. The incidence is increasing because of the emergence of a new virulent strain, the development of antibiotic resistance, and an increase in infection rates within populations once believed to be at low risk. Current strategies for the prevention, diagnosis, and treatment are cited. Transmission can be minimized with the use of gloves and gowns; proper hand washing with soap and water (alcohol-based washes do not prevent transmission); careful use and proper cleaning of shared patient equipment, such as blood-pressure cuffs, thermometers, and stethoscopes; and the use of bactericidal cleaning solutions. Restricted or judicious antibiotic use will also reduce the incidence of Clostridium difficile infections.

Potential value of repeat stool testing for Clostridium difficile stool toxin using enzyme immunoassay?

OBJECTIVE

The aim of this brief review is to summarize the literature as it relates to the potential value of repeat stool testing for Clostridium difficile (C. difficile) toxin using an enzyme immunoassay (EIA) for toxin A&B and also propose a potential newer algorithm for diagnosing C. difficile.

RESEARCH DESIGN AND METHODS

Two investigators conducted independent literature searches using PubMed, Web of Science, and Scopus until May 1st, 2010. All databases were searched using the terms Clostridium difficile, CDAD, antibiotic associated diarrhea, C. difficile in combination with enzyme immunoassay, enzyme linked immunosorbent assay, Clostridium difficile toxin A, Clostridium difficile toxin B, Clostridium difficile toxin and repeat stool testing. Articles which discussed EIA in C. difficile infection (CDI) patients were reviewed and relevant cross references also read and evaluated for inclusion. Selection bias could be a possible limitation of the approach used in selecting or finding articles for this article.

FINDINGS

The evidence for repeat stool testing for C. difficile toxin detection using toxin EIA is becoming weaker. Most recent published practice guidelines recommend a two- or three-step testing algorithm for the detection of C. difficile.

CONCLUSIONS

EIA for C. difficile stool toxin has a limited sensitivity, but, it does not warrant repeat stool testing. The data for this are suggestive but not conclusive. More studies and better tests are needed to have clear guidelines which can specify the number of tests needed in a diagnostic workup of suspected C. difficile infection. A two-step or three-step method in the diagnosis of C. difficile-associated diarrhea offered a marked increase in sensitivity compared to that of toxin A&B EIA alone.

Clostridium difficile infection and inflammatory bowel disease: Understanding the evolving relationship

Clostridium difficile (C. difficile) infection (CDI) is the leading identifiable cause of antibiotic-associated diarrhea. While there is an alarming trend of increasing incidence and severity of CDI in the United States and Europe, superimposed CDI in patients with inflammatory bowel disease (IBD) has drawn considerable attention in the gastrointestinal community. The majority of IBD patients appear to contract CDI as outpatients. C. difficile affects disease course of IBD in several ways, including triggering disease flares, sustaining activity, and in some cases, acting as an “innocent” bystander. Despite its wide spectrum of presentations, CDI has been reported to be associated with a longer duration of hospitalization and a higher mortality in IBD patients. IBD patients with restorative proctocolectomy or with diverting ileostomy are not immune to CDI of the small bowel or ileal pouch. Whether immunomodulator or corticosteroid therapy for IBD should be continued in patients with superimposed CDI is controversial. It appears that more adverse outcomes was observed among patients treated by a combination of immunomodulators and antibiotics than those treated by antibiotics alone. The use of biologic agents does not appear to increase the risk of acquisition of CDI. For CDI in the setting of underlying IBD, vancomycin appears to be more efficacious than metronidazole. Randomized controlled trials are required to clearly define the appropriate management for CDI in patients with IBD.

Real-time multiplex polymerase chain reaction assay for rapid detection of Clostridium difficile toxin-encoding strains

Clostridium difficile is considered an important emerging pathogen capable of causing disease in humans and animal species. In our study, we developed and evaluated a multiplex real-time polymerase chain reaction (PCR) assay for the detection of C. difficile genes encoding toxin A (tcdA), toxin B (tcdB), and binary toxin (cdtA and cdtB). The standardized real-time PCR assay for toxin genes of C. difficile was used to screen for toxigenic C. difficile in fecal samples from 71 preweaned calves, 53 retail ground meat samples, and 27 pasteurized milk samples. All samples were also examined for C. difficile using traditional culture techniques to validate the PCR assay. A total of 24 fecal samples (33.80%) were positive for toxigenic C. difficile using either multiplex real-time PCR or culture. Toxin-encoding C. difficile was detected in 23 enriched fecal samples using the multiplex real-time PCR assay and only 15 samples using culture techniques. C. difficile was not detected in ground meat or pasteurized milk by traditional culture or real-time PCR assay. Eleven fecal samples were positive for all 4 toxin genes, suggesting that preweaned calves may be a likely source for toxigenic C. difficile. On the basis of findings of our study, it can be concluded that multiplex real-time PCR carried out on samples enriched for C. difficile is a reliable, sensitive, and specific diagnostic tool for rapid screening and identification of samples contaminated with C. difficile.

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.

Algorithm combining toxin immunoassay and stool culture for diagnosis of Clostridium difficile infection

Enzyme immunoassays (EIA) to detect glutamate dehydrogenase or toxins A (TcdA) and B (TcdB), a cytotoxicity assay, and bacteriologic culture have disadvantages when applied individually to diagnosis of Clostridium difficile infections. Stool specimens (n = 1,596) were subjected to toxin detection via an enzyme-linked fluorescent immunoassay (ELFA; Vidas CDAB assay) and bacteriologic culture for toxigenic C. difficile in a three-step algorithm with additional toxigenic culture. Isolates (n = 163) from ELFA-negative stool specimens were examined via ELFA for toxin production. We amplified tcdA and tcdB from C. difficile isolates and tcdB from stool specimens that were ELFA positive or equivocal and culture negative, and we compared the results to those obtained with the three-step algorithm. More than 26% of stool specimens (419/1,596) were culture positive, yielding 248 isolates (59.2%) with both toxin genes (tcdA- and tcdB-positive isolates), 88 isolates (21.0%) with either tcdA or tcdB, and 83 (19.8%) that had no toxin genes (tcdA- and tcdB-negative isolates). Among 49 (culture-negative/ELFA-positive or -equivocal) stool specimens, 53.1% (26/49) represented tcdB-positive isolates. Therefore, the total number of PCR-positive cases was 362, and 27.1% (98/362) of these were detected through toxigenic culture. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 63.3%, 96.7%, 90.5%, and 92.4% (ELFA alone); 92.8%, 93.3%, 80.2%, and 97.8% (culture); and 70.7%, 91.4%, 95.5%, and 100% (three-step algorithm ELFA and bacterial culture with toxigenic culture), respectively, with culture and PCR for tcdA and tcdB as the standards. Thus, sensitivity and specificity were highest using culture and ELFA, respectively, but we recommend the three-step algorithm comprising EIA to detect both toxins and toxigenic culture for C. difficile as a practical method for achieving better PPV and NPV.

Peripartum Clostridium difficile infection: case series and review of the literature

Clostridium difficile infection (CDI) in nonhospitalized patients has been reported with increased frequency. An association between CDI and pregnancy has not been stressed. This review will report 4 cases of peripartum CDI with characterization of the infecting strain and a literature review. A PubMed search identified 24 recorded cases of peripartum CDI; information was available for 14 cases. Most patients (91%) received prophylactic antibiotics during delivery or for treatment of bacterial infections (50%). All patients reported diarrhea. Two of our reported cases without known risk factors were found by polymerase chain reaction analysis to be infected with an epidemic and hypervirulent C difficile strain. These cases demonstrate the need for clinicians to consider CDI in patients with severe diarrhea, even if they do not have the traditional risk factors for CDI, such as antibiotic use or concurrent hospitalizations. Further research into the scope and risk factors for peripartum CDI is warranted.

Historical perspectives on studies of Clostridium difficile and C. difficile infection

The initial period of studies on Clostridium difficile (published during 1978-1980) appeared to provide a nearly complete portfolio of criteria for diagnosing and treating C. difficile infection (CDI). The putative pathogenic role of C. difficile was established using Koch's postulates, risk factors were well-defined, use of a cell cytotoxicity assay as the diagnostic test provided accurate results, and treatment with oral vancomycin was highly effective and rapidly incorporated into practice. During the next 10 years, enzyme immunoassays (EIAs) were introduced as diagnostic tests and became the standard for most laboratories. This was not because EIAs were as good as the cell cytotoxicity assay; rather, EIAs were inexpensive and yielded results quickly. Similarly, metronidazole became the favored treatment because it was less expensive and quelled fears of colonization with vancomycin-resistant organisms, not because it was better than vancomycin therapy. Cephalosporins replaced clindamycin as the major inducers of CDI because they were so extensively used, rather than because they incurred the same risk. Some serious issues remained unresolved during this period: the major challenges were to determine ways to treat seriously ill patients for whom it was not possible to get vancomycin into the colon and to find methods that stop persistent relapses. These concerns persist today.

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.

Clostridium difficile: recent epidemiologic findings and advances in therapy

Clostridium difficile-associated disease (CDAD) has become an important public health problem. The causative organism is acquired by the oral route from an environmental source or by contact with an infected person or a health care worker who serves as a vector. Disruption of the bowel microflora, generally by antibiotics, creates an environment that allows C. difficile to proliferate. Organisms produce toxins A and B, which cause intense inflammation of the colonic mucosa. The syndrome that results includes severe diarrhea, fever, abdominal pain, and leukocytosis. A new strain of C. difficile has become prevalent in the United States, Canada, and the United Kingdom. Identified by pulsed-field gel electrophoresis (PFGE), this strain is called North America PFGE type 1, abbreviated as NAP-1. Clostridium difficile NAP-1 characteristically generates large amounts of toxins A and B, as well as an additional binary toxin and is associated with enhanced morbidity and a poor response to antibiotic therapy. Mild cases of CDAD may respond to cessation of antibiotic therapy, perhaps related to antibody production by the infected person, but most infected persons require antimicrobial therapy. Vancomycin has been approved by the United States Food and Drug Administration for treatment of CDAD, but reluctance to use this antibiotic in the hospital setting has led to reliance on metronidazole as first-line therapy. Recent studies show a high rate of failure, due either to infection by NAP-1 or to the presence, in hospitals, of older and sicker adults who have been treated with many broad-spectrum antibiotics. Nitazoxanide, bacitracin, teicoplanin, and fusidic acid are additional agents that have published efficacy for this indication in humans. Rifaximin and PAR-101 are under investigation. Other therapies, including polymers that bind C. difficile toxin and monoclonal antibodies to toxins, and preventive measures such as toxoid vaccines are also under study.

Association of interleukin-8 polymorphism and immunoglobulin G anti-toxin A in patients with Clostridium difficile-associated diarrhea

BACKGROUND & AIMS

Previous studies have shown that failure to produce serum antibodies to C. difficile (CD) toxin A is associated with more severe and recurrent C. difficile-associated diarrhea (CDAD); and that presence of AA genotype in the interleukin (IL)-8 gene promoter -251 position is associated with increased susceptibility to CDAD. This study examined the relationship between serum immunoglobulin G antibodies to CD toxin A and the presence of IL-8 AA genotype in hospitalized patients with CDAD.

METHODS

At enrollment, blood for host IL-8 genotype, serum for CD anti-toxin A antibody, and stool for IL-8 by enzyme-linked immunosorbent assay were obtained in CDAD patients and in CD-toxin-negative asymptomatic controls.

RESULTS

Nine of 24 (37.5%) CDAD and 3 of 20 (15%) controls were CD anti-toxin A positive (P = .095). Eleven of 24 (45.8%) CDAD subjects were positive for AA genotype compared with 5 of 20 (25.0%) controls (P = .0019). One of 11 (9.1%) CDAD with AA genotype were positive for anti-toxin A antibodies compared with 8 of 13 (61.5%) non-AA genotype CDAD (P < .0001). Fecal IL-8 concentration for the single antibody-positive CDAD subject with AA genotype was lower than the median level of 822 microg/mL seen in 10 anti-toxin A antibody-negative subjects with CDAD.

CONCLUSIONS

This study provided evidence that host susceptibility to C. difficile diarrhea is related both to a defective humoral immune response to CD toxin A and host IL-8 AA genotype.

Evaluation of three rapid assays for detection of Clostridium difficile toxin A and toxin B in stool specimens

Diagnosis of Clostridium difficile-associated disease continues to be difficult for clinical microbiology laboratories. The aim of this study was to evaluate the performance of three enzyme immunoassays for detection of C. difficile toxins A and B: the recently marketed rapid enzyme immunoassay Ridascreen Clostridium difficile Toxin A/B (R-Biopharm, Darmstadt, Germany) and two established enzyme immunoassays, the C. difficile Tox A/B II Assay (TechLab, Blacksburg, VA, USA) and the ProSpecT C. difficile Toxin A/B Microplate Assay (Remel, Lenexa, KS, USA). Stool specimens (n = 383) from patients with a clinical diagnosis of antibiotic-associated diarrhea were examined by these three enzyme immunoassays and were additionally cultured for C. difficile on selective agar. Samples giving discordant enzyme immunoassay results underwent confirmatory testing by tissue culture cytotoxin B assay and by PCR for toxin A (tcdA) and toxin B (tcdB) genes from C. difficile. Using the criteria adopted for this study, 60 (15.7%) samples tested positive for toxins A and/or B. Sensitivity and specificity of the enzyme immunoassays were, respectively, 88.3 and 100% for the TechLab enzyme immunoassay, 91.7 and 100% for the R-Biopharm enzyme immunoassay, and 93.3 and 100% for the Remel enzyme immunoassay. The differences between these results are statistically not significant (p > 0.05). The results show that all three enzyme immunoassays are acceptable tests for the detection of C. difficile toxins A and B directly in fecal specimens or in toxigenic cultures.

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.

Prevalence of diarrhea at a university hospital and association with modifiable risk factors

OBJECTIVE

To assess the prevalence of diarrhea at a university-affiliated medical center and the presence of modifiable risk factors.

METHODS

A point prevalence survey was conducted. All patients hospitalized for more than 24 hours were asked if they were experiencing diarrhea. Stools of patients not previously tested were assessed for Clostridium difficile (CD) toxins A and B. Univariate analysis and multivariate logistic regression analyses were used to identify modifiable variables associated with diarrhea (significance defined as p < 0.05).

RESULTS

Four hundred eighty-five hospitalized patients were interviewed, of whom 60 (12.4%) reported 2 or more loose, unformed stools in the last 24 hours. Six of 81 (7.4%) patients tested positive for CD toxin. Three (50%) of the CD toxin-positive patients had not previously been tested during the current admission. Patients with diarrhea were more likely to have tested CD toxin-positive (OR 10.6; p = 0.01), received antibiotics (OR 1.79; p = 0.04), or been hospitalized for a longer period of time (p = 0.04).

CONCLUSIONS

Diarrhea was prevalent in 12.4% of hospitalized patients at a large university hospital at one point in time. Patients with diarrhea were more likely to have CD infection, receive antibiotics, or experience a longer hospitalization. Half of the CD diarrhea cases occurring in the hospital had been previously unidentified. Hospitalized patients should be evaluated for diarrhea on an ongoing basis with appropriate interventions instituted.

A common polymorphism in the interleukin 8 gene promoter is associated with Clostridium difficile diarrhea

OBJECTIVE

Mucosal interleukin 8 (IL-8) and neutrophil recruitment are central to the pathogenesis of Clostridium difficile (CD) toxin-induced diarrhea (CDD). We hypothesized that like other inflammatory mucosal infections, susceptibility to CDD would relate to genetically determined variations in the production of IL-8.

METHODS

Fecal IL-8 production and single nucleotide polymorphism (SNP) frequency in the -251 region of the IL-8 gene were determined in hospitalized patients: 42 with CDD, 42 with CD-negative diarrhea, and 41 without diarrhea. Cases and controls were matched by age, length of hospital stay, comorbidity, and receipt of antibiotics.

RESULTS

An association was found between the IL-8 -251 A/A allele and occurrence of CDD, 39%versus 16% (OR = 3.26, 95% CI 1.09-9.17) and 17% (OR = 5.50, 95% CI 1.22-24.8) for the two control groups. Comparing results by IL-8 genotype for the CDD cases, median and mean fecal IL-8 levels were significantly higher for the -251 A/A genotype (p = 0.03 for median and 0.001 for mean).

CONCLUSIONS

These studies indicate a common SNP in the IL-8 gene is associated with increased susceptibility to CDD and with increased fecal IL-8 in diarrheal stools.

Laboratory diagnosis of Clostridium difficile-associated diarrhoea: a plea for culture

A routine protocol for diagnosing Clostridium difficile-associated diarrhoea (CDAD) based on both faecal-cytotoxin detection and toxigenic culture was adopted by the microbiology laboratory of the St Luc-UCL University Hospital in Brussels in 1997. A toxigenic culture is a faecal culture followed, in the case of positivity, by a direct immunoassay on colonies to detect toxin A production. The results obtained over the past 7 years in the hospital are reviewed here. A total of 10,552 diarrhoeal stools from 7042 patients were analysed, of which 9494 were negative for all tests. A total of 1058 samples (10 %) from 794 patients were culture-positive, of which 460 (4.4 %) were positive for a faecal cytotoxin. The remaining 598 cultures were tested for toxin A on colonies; 355 of them were positive, which is 3.4 % of the total, and the remaining 243 (2.3 %) were negative. The positivity of the faecal-cytotoxin assay was statistically linked to the number of colonies observed on the culture plate. In conclusion, over a 7 year period, toxigenic culture allowed the diagnosis of 355 cases of CDAD that would have been missed by a protocol using a faecal-cytotoxin assay alone. In terms of both patient care, prevention of environmental contamination and prevention of risk of a hospital outbreak, it is proposed that these results justify the recommendation to perform both faecal-toxin assay and culture in routine medical practice.

Multiplex PCR targeting tpi (triose phosphate isomerase), tcdA (Toxin A), and tcdB (Toxin B) genes for toxigenic culture of Clostridium difficile

A multiplex PCR toxigenic culture approach was designed for simultaneous identification and toxigenic type characterization of Clostridium difficile isolates. Three pairs of primers were designed for the amplification of (i) a species-specific internal fragment of the tpi (triose phosphate isomerase) gene, (ii) an internal fragment of the tcdB (toxin B) gene, and (iii) an internal fragment of the tcdA (toxin A) gene allowing distinction between toxin A-positive, toxin B-positive (A+B+) strains and toxin A-negative, toxin B-positive (A-B+) variant strains. The reliability of the multiplex PCR was established by using a panel of 72 C. difficile strains including A+B+, A-B-, and A-B+ toxigenic types and 11 other Clostridium species type strains. The multiplex PCR assay was then included in a toxigenic culture approach for the detection, identification, and toxigenic type characterization of C. difficile in 1,343 consecutive human and animal stool samples. Overall, 111 (15.4%) of 721 human samples were positive for C. difficile; 67 (60.4%) of these samples contained A+B+ toxigenic isolates, and none of them contained A-B+ variant strains. Fifty (8%) of 622 animal samples contained C. difficile strains, which were toxigenic in 27 (54%) cases, including 1 A-B+ variant isolate. Eighty of the 721 human stool samples (37 positive and 43 negative for C. difficile culture) were comparatively tested by Premier Toxins A&B (Meridian Bioscience) and Triage C. difficile Panel (Biosite) immunoassays, the results of which were found concordant with toxigenic culture for 82.5 and 92.5% of the samples, respectively. The multiplex PCR toxigenic culture scheme described here allows combined diagnosis and toxigenic type characterization for human and animal C. difficile intestinal infections.

Prevalence and characterization of a binary toxin (actin-specific ADP-ribosyltransferase) from Clostridium difficile

In addition to the two large clostridial cytotoxins (TcdA and TcdB), some strains of Clostridium difficile also produce an actin-specific ADP-ribosyltransferase, called binary toxin CDT. We used a PCR method and Southern blotting for the detection of genes encoding the enzymatic (CDTa) and binding (CDTb) components of the binary toxin in 369 strains isolated from patients with suspected C. difficile-associated diarrhea or colitis. Twenty-two strains (a prevalence of 6%) harbored both genes. When binary toxin production was assessed by Western blotting, 19 of the 22 strains reacted with antisera against the iota toxin of C. perfringens (anti-Ia and anti-Ib). Additionally, binary toxin activity, detected by the ADP-ribosyltransferase assay, was present in only 17 of the 22 strains. Subsequently, all 22 binary toxin-positive strains were tested for the production of toxins TcdA and TcdB, toxinotyped, and characterized by serogrouping, PCR ribotyping, arbitrarily primed PCR, and pulsed-field gel electrophoresis. All binary toxin-positive strains also produced TcdB and/or TcdA. However, they had significant changes in the tcdA and tcdB genes and belonged to variant toxinotypes III, IV, V, VII, IX, and XIII. We could differentiate 16 profiles by using typing methods, indicating that most of the binary toxin-positive strains were unrelated.

Clinical application of polymerase chain reaction to diagnose Clostridium difficile in hospitalized patients with diarrhea

BACKGROUND & AIMS

Clostridium difficile is a common cause of diarrhea in hospitalized patients and is associated with significant morbidity and cost. The current diagnostic standard, enzyme immunoassay (EIA), has low sensitivity, leading to duplicate testing and empiric treatment. We sought to show the usefulness and potential cost effectiveness of polymerase chain reaction (PCR) amplification of toxin B gene for diagnosis of C. difficile-induced diarrhea.

METHODS

A total of 148 stool samples from academic and community-based hospitals were sent for EIA testing and were evaluated prospectively for the presence of toxin B gene by PCR. Results were compared with EIA regarding sensitivity, specificity, and predictive values. Medical charts were reviewed to determine the following: (1) number of EIAs sent per admission, (2) number sent within a 24-hour time period, and (3) how caregivers practiced based on EIA results.

RESULTS

The mean age of 130 patients was 55 years. EIA and PCR were positive in 6.8% and 13.6% of patients, respectively. EIA sensitivity was 40%, specificity was 98%, and positive and negative predictive values were 80% and 91%, respectively. The cost of the PCR was $22/sample. Empiric treatment for C. difficile was given unnecessarily in 42% of EIA-negative results. Thirty percent of patients had 3 or more EIAs sent during their hospital admission. Of patients with multiple samples sent, 57% had more than 1 sample sent in a 24-hour period.

CONCLUSIONS

Many physicians do not conform to practice guidelines regarding recommended diagnosis and empiric treatment of C. difficile. Toxin B gene PCR represents a more sensitive and potentially cost-effective method to diagnose C. difficile-induced diarrhea than EIA and should be considered for use as an alternative diagnostic standard.

Clostridium difficile-associated diarrhea in adults

Clostridium difficile is the most important cause of nosocomial diarrhea in adults. Illness may range from mild watery diarrhea to life-threatening colitis. An antecedent disruption of the normal colonic flora followed by exposure to a toxigenic strain of C. difficile are necessary first steps in the pathogenesis of disease. Diagnosis is based primarily on the detection of C. difficile toxin A or toxin B. First-line treatment is with oral metronidazole therapy. Treatment with oral vancomycin therapy should be reserved for patients who have contraindications or intolerance to metronidazole or who fail to respond to first-line therapy.

Clostridium difficile associated diarrhoea in hospitalised patients: onset in the community and hospital and role of flexible sigmoidoscopy

OBJECTIVES

Clostridium difficile associated diarrhoea (CDAD) is a hospital acquired infection in which optimal methods for diagnosis and the scale of the problem in the community remain to be determined. In hospitalised patients with CDAD, we aimed to (i) study patients in whom the onset of diarrhoea was in the community and (ii) investigate the role of bedside flexible sigmoidoscopy in diagnosis.

METHODS

Patients with CDAD (onset in hospital or community) were studied prospectively. In those with diarrhoea of unknown aetiology, flexible sigmoidoscopy was compared with stool assay for C difficile cytotoxin.

RESULTS

Of 136 patients with CDAD (which was associated with antibiotic exposure in 96%), diarrhoea started in the community in 38 (28%; majority in own home) and while an inpatient in 98 (72%). The majority with CDAD onset in the community had been hospitalised over the preceding 12 months (86.8% v 57.1% in the hospital onset group; p<0.001). In 56 patients with pseudomembranous colitis at sigmoidoscopy, the stool C difficile cytotoxin test was negative in 29 (52%) but toxigenic C difficile was isolated from all of nine stool samples cultured. Of patients with pseudomembranous colitis, 30.4% relapsed over the subsequent 57.7(4.2) days.

CONCLUSIONS

In a significant proportion of hospitalised patients with CDAD, diarrhoea started in the community. However, the majority of these had been hospital inpatients previously when they may have acquired C difficile, with the subsequent onset of diarrhoea in the community following exposure to antibiotics. Flexible sigmoidoscopy is superior to the stool C difficile cytotoxin test in a subgroup of patients with pseudomembranous colitis. Sigmoidoscopy should therefore be considered in all hospitalised patients with diarrhoea in whom the stool test for C difficile cytotoxin and enteric pathogens is negative.