Clostridium difficile-associated diarrhea and colitis

Epidemiology of Clostridium difficile infection in a large population of hospitalized US military veterans

The Patient Treatment File (PTF) of the Department of Veterans Affairs (VA) comprises the computerized records of all inpatients treated at all VA hospitals throughout the United States. The database was utilized to study the clinical epidemiology and impact of C. difficile colitis on health care among hospitalized US military veterans. The computerized medical records of 15,091 cases with C. difficile colitis and 61,931 controls without the diagnosis were extracted from the annual files between 1993 and 1998. Of all patients admitted to the hospital, 1% were diagnosed with C. difficile colitis, in 16% of whom it was listed as the primary discharge diagnosis. C. difficile colitis was more likely to occur in elderly white patients with multiple comorbid conditions. Compared with a control population of hospitalized patients without C. difficile colitis, the case population was subjected to more medical and surgical procedures and experienced longer hospital stays. The diagnosis of C. difficile colitis was associated with more frequent admissions to the intensive care unit and higher hospital-related and subsequent mortality. Eleven percent of the cases were admitted to hospital a second time after a mean of 202 days, 2.5% were readmitted a third time after an additional 182 days, and 0.8% were readmitted a fourth time after an additional 194 days. In conclusion, as old age, multiple comorbid conditions, a high number of medical and surgical intervention, and long hospitalization constitute the main risk factors for the development of C. difficile colitis, efforts at prevention should be directed primarily towards patients who present with these characteristics.

Gastrointestinal infections

Advances in public health have reduced the risk of contracting certain enteric diseases, but many remain, and new pathogens have emerged and/or recently have been discovered. The pathogenic agents are varied and consist of a variety of bacteria and select viruses and parasites. Selected use of microbiologic assays to detect these pathogens is encouraged. When tests are ordered non-judiciously, costs rapidly accrue. The age of the patient, time of year, travel history, and clinical presentation all provide clues to the etiologic agent. Microbiologic assays should be used judiciously to confirm or exclude the likely infectious agents.

Clostridium difficile

Clostridium difficile is a major cause of antibiotic-associated diarrhea and colitis. The incidence of infection with this organism is increasing in hospitals worldwide, consequent to the widespread use of broad-spectrum antibiotics. Pathogenic strains of C. difficile produce two protein exotoxins, toxin A and toxin B, that cause colonic mucosal injury and inflammation. Many patients who are colonized are asymptomatic, and recent evidence indicates that diarrhea and colitis occur in those individuals who lack a protective antitoxin immune response. In patients who do develop symptoms, the spectrum of C. difficile disease ranges from mild diarrhea to fulminant pseudomembranous colitis. Prevention of nosocomial C. difficile infection involves judicious use of antibiotics and multidisciplinary infection control measures to reduce environmental contamination and patient cross-infection. Ultimately, active or passive immunization against C. difficile may be an effective means of controlling the growing problem of nosocomial C. difficile diarrhea and colitis.

Laboratory approaches to infectious diarrhea

Future applications of advanced molecular diagnostics in clinical laboratories will enhance significantly capabilities to diagnose bacterial, parasitic, and viral agents in the early course of disease through enhanced assay sensitivities and specificities and improved turnaround times, theoretically leading to more timely and directed therapeutic intervention. Until such time, clinicians must continue to rely on clinical judgment and the diverse battery of traditional culture techniques, direct examination (including light microscopy and electron microscopy), and immunoassays that are available. Cost considerations and the ever-increasing array of infectious agents responsible for infectious gastroenteritis will continue to drive the development of practice guidelines to assist practitioners with reasoned and reasonable approaches to management of diarrheal illnesses.

Evaluation of methods for detection of toxins in specimens of feces submitted for diagnosis of Clostridium difficile-associated diarrhea

Clostridium difficile is the principal pathogen associated with hospital-acquired acute diarrheal disease. We have evaluated the performances of six approaches for diagnosis of C. difficile-associated diarrhea (CDAD). Consecutive stool specimens (n = 200) from 133 patients were examined by cytotoxin assay, by culture of C. difficile on cycloserine-cefoxitin-fructose agar, and by toxin detection using four rapid immunoassay systems (Oxoid Toxin A test, ImmunoCard Toxin A test, TechLab Tox A/B II test, and Premier Toxins A&B test). A diagnosis of CDAD was established for 35 (27%) patients (representing 29% of specimens). The adjusted sensitivity and specificity of the methods were, respectively, 98 and 99% for the cytotoxin assay, 54 and 99% for ImmunoCard, 50 and 98% for Oxoid, 79 and 98% for TechLab, 80 and 98% for Premier, and 57 and 100% for culture. The TechLab and Premier assays are acceptable tests for diagnosis of CDAD but are not equivalent to the cytotoxin assay.

Laboratory diagnosis of Clostridium difficile-associated diarrhea and colitis: usefulness of Premier Cytoclone A+B enzyme immunoassay for combined detection of stool toxins and toxigenic C. difficile strains

Detection of Clostridium difficile toxins A and B in stools by Premier Cytoclone A+B enzyme immunoassay (EIA) was compared with detection by stool culture for C. difficile followed by detection of toxigenic isolates using the same EIA. Chart reviews were performed to evaluate the likelihood of C. difficile-associated diarrhea and colitis (CADC) for all patients with at least one positive toxin assay. While the toxins were detected in 58 of 85 consecutive CADC patients by both assays, CADC in 5 patients was detected only by stool toxin assay, and in 22 patients CADC was detected only by toxigenic culture. Our results suggest that for laboratories using a rapid toxin A+B EIA, direct toxin detection in stools should be combined with toxigenic culture in cases in which there is a negative stool toxin assay.

Management and Prevention of Clostridium difficile-Associated Diarrhea

Clostridium difficile is a major cause of antibiotic-associated diarrhea. While treatment regimens for C. difficile have been available for decades, they remain less than optimal due to the frequent recurrences that occur after therapy is completed. Moreover, the morbidity and expense associated with C. difficile have underscored the need for more effective preventive measures than are currently available. In this review, we outline the current recommendations for treatment and prevention of C. difficile infection and, highlight some promising new approaches that may help to control this common nosocomial pathogen in the future.

Update on Clostridium difficile infection

Clostridium difficile is a major cause of antibiotic-associated diarrhea in hospital and community settings, spreading endemic and epidemic disease in developed and developing areas throughout the world. Its toxins A and B cause epithelial disruption, inflammation, and secretion. Diagnosis of infection with C. difficile is based on appropriate clinical presentation and demonstration of the presence of either toxin A or B, or both. Established treatment is still predominantly metronidazole and vancomycin. The association of antibiotic therapy with recurrent disease and antimicrobial resistance, especially vancomycin-resistant enterococci, highlights the need for new approaches to managing C. difficile infection.

Pseudomembranous Colitis Caused by C. difficile

Pseudomembranous colitis (PMC) is a considerable clinical concern for several reasons, including disease severity, increasing frequency, complications, and development of antibiotic-resistant organisms. C. difficile infection should be considered in anyone who develops diarrhea during or after antibiotic therapy; PMC is the most serious manifestation of C. difficile disease. PMC is effectively treated with either metronidazole or vancomycin. Metronidazole should be first-line therapy, reserving vancomycin for those who are very ill or who do not respond to metronidazole or cannot take it (ie, first trimester pregnancy, side effects). Recurrent C. difficile disease (which occurs in approximately 20% of C. difficile cases) is best treated with an antibiotic in combination with a biotherapeutic agent. Prevention of epidemics of C. difficile requires careful hand washing and cleaning of environmental surfaces. Antibiotic restriction may be necessary in some cases.

Asymptomatic carriage of Clostridium difficile and serum levels of IgG antibody against toxin A

BACKGROUND

Clostridium difficile infection can result in asymptomatic carriage, mild diarrhea, or fulminant pseudomembranous colitis. We studied whether antibody responses to C. difficile toxins affect the risks of colonization, diarrhea, and asymptomatic carriage.

METHODS

We prospectively studied C. difficile infections in hospitalized patients who were receiving antibiotics. Serial stool samples were tested for C. difficile colonization by cytotoxin assay and culture. Serum antibody (IgA, IgG, and IgM) levels and fecal antibody (IgA and IgG) levels against C. difficile toxin A, toxin B, and nontoxin antigens were measured by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Of 271 patients, 37 (14 percent) were colonized with C. difficile at the time of admission, 18 of whom were asymptomatic carriers. An additional 47 patients (17 percent) became infected in the hospital, 19 of whom remained asymptomatic. The baseline antibody levels were similar in the patients who later became colonized and those who did not. After colonization, those who became asymptomatic carriers had significantly greater increases in serum levels of IgG antibody against toxin A than did the patients in whom C. difficile diarrhea developed (P<0.001). The adjusted odds ratio for diarrhea was 48.0 (95 percent confidence interval, 3.4 to 678) among patients with colonization who had a serum level of IgG antibody against toxin A of 3.00 ELISA units or less, as compared with patients with colonization who had a level of more than 3.00 ELISA units.

CONCLUSIONS

We find no evidence of immune protection against colonization by C. difficile. However, after colonization there is an association between a systemic anamnestic response to toxin A, as evidenced by increased serum levels of IgG antibody against toxin A, and asymptomatic carriage of C. difficile.

Epidemics of diarrhea caused by a clindamycin-resistant strain of Clostridium difficile in four hospitals

BACKGROUND

Large outbreaks of diarrhea caused by a newly recognized strain of Clostridium difficile occurred in four hospitals located in different parts of the United States between 1989 and 1992. Since frequent use of clindamycin was associated with the outbreak in one of the hospitals, we examined the resistance genes of the epidemic-strain isolates and studied the role of clindamycin use in these outbreaks.

METHODS

Case-control studies were performed at three of the four hospitals to assess the relation of the use of clindamycin to C. difficile-associated diarrhea. All isolates of the epidemic strain and representative isolates of other strains identified during each outbreak were tested for susceptibility to clindamycin. Chromosomal DNA from these representative isolates was also analyzed by dot blot hybridization and amplification with the polymerase chain reaction (PCR) with the use of probes and primers from a previously described determinant of erythromycin resistance - the erythromycin ribosomal methylase B (ermB) gene - found in C. perfringens and C. difficile.

RESULTS

In a stratified analysis of the case-control studies with pooling of the results according to the Mantel-Haenszel method, we found that the use of clindamycin was significantly increased among patients with diarrhea due to the epidemic strain of C. difficile, as compared with patients whose diarrhea was due to nonepidemic strains (pooled odds ratio, 4.35; 95 percent confidence interval, 2.02 to 9.38; P<0.001). Exposure to other types of antibiotics or hospitalization in a surgical ward was not significantly associated with the risk of C. difficile-associated diarrhea due to the epidemic strain. All epidemic-strain isolates were highly resistant to clindamycin (minimal inhibitory concentration, >256 microg per milliliter). DNA hybridization and PCR analysis showed that all these isolates had an ermB gene, which encodes a 23S ribosomal RNA methylase that mediates resistance to macrolide, lincosamide, and streptogramin antibiotics. Only 15 percent of the nonepidemic strains were resistant to clindamycin.

CONCLUSIONS

A strain of C. difficile that is highly resistant to clindamycin was responsible for large outbreaks of diarrhea in four hospitals in different states. The use of clindamycin is a specific risk factor for diarrhea due to this strain. Resistance to clindamycin further increases the risk of C. difficile-associated diarrhea, an established complication of antimicrobial use.

Roles of Intracellular Calcium and NF-κB in the Clostridium difficile Toxin A-Induced Up-Regulation and Secretion of IL-8 from Human Monocytes

Clostridium difficile causes an intense inflammatory colitis through the actions of two large exotoxins, toxin A and toxin B. IL-8 is believed to play an important role in the pathophysiology of C. difficile-mediated colitis, although the mechanism whereby the toxins up-regulate the release of IL-8 from target cells is not well understood. In this study, we investigated the mechanisms through which toxin A induces IL-8 secretion in human monocytes. We found that cellular uptake of toxin A is required for the up-regulation of IL-8, an effect that is not duplicated by a recombinant toxin fragment comprising the cell-binding domain alone. Toxin A induced IL-8 expression at the level of gene transcription and this effect occurred through a mechanism requiring intracellular calcium and calmodulin activation. Additionally, the effects of toxin A were inhibited by the protein tyrosine kinase inhibitor genistein, but were unaffected by inhibitors of protein kinase C and phosphatidylinositol-3 kinase. We determined that toxin A activates nuclear translocation of the transcription factors NF-κB and AP-1, but not NF-IL-6. NF-κB inhibitors blocked the ability of toxin A to induce IL-8 secretion, and supershift analysis indicated that the major isoform of NF-κB activated by the toxin is a p50-p65 heterodimer. This study is the first to identify intracellular signaling pathways and transcription factors involved in the C. difficile toxin-mediated up-regulation of IL-8 synthesis and release by target cells. This information should increase our understanding of the pathogenesis of C. difficile colitis and the nature of IL-8 gene regulation as well.

Susceptibility testing of Clostridium difficile against metronidazole and vancomycin by disk diffusion and Etest

A prospective study on the susceptibility of Clostridium difficile to metronidazole and vancomycin using the Etest and disk diffusion test was performed over a 6-month period. One hundred strains were tested; one strain was highly resistant to metronidazole (MIC = 64 micrograms/mL). The zone size of inhibition by the disk diffusion test correlated with the MIC as determined by the Etest (regression coefficient = -0.043 for metronidazole and -0.044 for vancomycin, p < 0.001 for both antibiotics). However, the correlation coefficient was low for both metronidazole (r = 0.574) and vancomycin (r = 0.473); hence the zone of inhibition by disk diffusion test could not predict the MIC satisfactorily. Metronidazole is still the first-line antibiotic for the treatment of C. difficile-associated diarrhea because the incidence of metronidazole resistant strains remains very low. However, the efficacy of metronidazole in the treatment of infections attributable to isolates with high-level metronidazole resistance may be compromised because the fecal concentration of metronidazole is relatively low when compared with the MIC values of the less susceptible strains. Oral vancomycin is the drug of choice under such circumstances, as its fecal concentration is much higher than that of metronidazole.

Evaluation of an interdisciplinary re-isolation policy for patients with previous Clostridium difficile diarrhea

BACKGROUND

Diarrhea caused by Clostridium difficile is increasingly recognized as a nosocomial problem. The effectiveness and cost of a new program to decrease nosocomial spread by identifying patients scheduled for readmission who were previously positive for toxin was evaluated.

METHODS

The Memorial Sloan-Kettering Cancer Center is a 410-bed comprehensive cancer center in New York City. Many patients are readmitted during their course of cancer therapy. In 1995 as a result of concern about the nosocomial spread of C difficile, we implemented a policy that all patients who were positive for C difficile toxin in the previous 6 months with no subsequent toxin-negative stool as an outpatient would be placed into contact isolation on readmission pending evaluation of stool specimens. Patients who were previously positive for C difficile toxin were identified to infection control and admitting office databases via computer. Admitting personnel contacted infection control with all readmissions to determine whether a private room was required.

RESULTS

Between July 1, 1995, and June 30, 1996, 47 patients who were previously positive for C difficile toxin were readmitted. Before their first scheduled readmission, the specimens for 15 (32%) of these patients were negative for C difficile toxin. They were subsequently cleared as outpatients and were readmitted without isolation. Workup of the remaining 32 patients revealed that the specimens for 7 patients were positive for C difficile toxin and 86 isolation days were used. An additional 25 patients used 107 isolation days and were either cleared after a negative specimen was obtained in-house or discharged without having an appropriate specimen sent. Four patients (9%) had reoccurring C difficile after having toxin-negative stools. We estimate (because outpatient specimens were not collected) the cost incurred at $48,500 annually, including the incremental cost of hospital isolation and equipment.

CONCLUSION

Our policy to control the spread of nosocomial C difficile required interdisciplinary cooperation between infection control and the admitting department. By identifying patients who were positive for toxin through admitting, we were able to place all potentially infected patients into isolation. Our positivity rate of 15% on readmission demonstrates the importance of this policy. The cost of controlling C difficile can be significantly lowered by clearing patients who were previously positive for toxin before hospital readmission.

Effectiveness of infection control program in controlling nosocomial Clostridium difficile

OBJECTIVE

To report the effectiveness of use of comprehensive infection control measures to reduce the incidence of Clostridium difficile (CD) in an acute-care teaching hospital.

METHODS

All CD infections were reviewed by the infection control coordinator from 1987 to 1996. The Centers for Disease Control and Prevention's nosocomial infection definition was used. CD-inclusion criteria remained unchanged during the study period. Interventions were started in 1990.

INTERVENTIONS

The interventions used were: (1) Isolation policy-revision and enforcement, which included universal precautions policy, (2) educational program-monthly to all health care workers, (3) phenolic disinfectant for environmental cleaning, (4) triclosan (0.03%) soap for handwashing, (5) centralization of sterilization department, (6) cart-washer installation, and (7) aggressive surveillance activity.

RESULTS

From 1987 to 1989, before the interventions, a total of 466 CD infections (mean 155 per year) occurred. From 1990 to 1996, after the interventions, 475 infections (mean 67 per year) occurred. Incidence of CD decreased by 60% from 1990 to 1996.

CONCLUSION

The sustained decrease of nosocomial CD during the 7-year period demonstrated the effectiveness of aggressive infection control measures that involve multiple disciplines.

Laboratory surveillance method for nosocomial Clostridium difficile diarrhea

BACKGROUND

Clostridium difficile is the most common infectious cause of endemic nosocomial diarrhea, but traditional surveillance methods for this infection can be time-consuming. The purpose of this article is to (1) describe a laboratory surveillance method for nosocomial diarrhea and nosocomial Clostridium difficile diarrhea (CDD) that does not require chart review and (2) describe some of the epidemiology of these infections at a university-affiliated, public hospital by using this surveillance method.

METHODS

The main assumption underlying the surveillance method is that all patients with nosocomial diarrhea have a C. difficile stool toxin assay performed. On the basis of this assumption, the frequency of testing stool samples for toxin is considered a surrogate for the occurrence of nosocomial diarrhea; it is also assumed that the results of the stool toxin assay distinguish between those with (positive assay) and without (negative assay) CDD. During the study period (January 1, 1993, to August 30, 1996) surveillance for nosocomial CDD was performed by monitoring results of C. difficile stool toxin assays done with the Cytoclone A and B enzyme immunoassay. Each month a list of results of all assays performed was reviewed and patients were excluded on the basis of the following criteria. First, patients with assays done within the first 4 days of admission were assumed to have community-acquired diarrhea and excluded. Among patients with assays done > 4 days after admission, patients with two or more assays done within a 7-day period were counted only once; repeated assays (positive or negative) in the 14 days after an initial positive assay (indicating nosocomial CDD) were excluded, but assays done more than 14 days after a positive or a negative assay were counted separately (representing a relapse or new episode of diarrhea). Patients remaining on the list after all the exclusion criteria were applied represented those with nosocomial diarrhea.

RESULTS

The mean (+/- SD) frequency of episodes of nosocomial diarrhea per month for each study year (1993, 1994, 1995, and first 8 months of 1996) was 52.6 +/- 16.2, 51.4 +/- 10.5, 49.2 +/- 9.3, 57.8 +/- 11.6, respectively (p = 0.48 by ANOVA); the mean frequency of nosocomial diarrhea per 1000 admissions per month was 48.4 +/- 14.5, 47.7 +/- 10.9, 44.0 +/- 9.6, and 51.6 +/- 9.3, respectively (p = 0.52); and the mean frequency of nosocomial CDD episodes per 100 episodes of nosocomial diarrhea was 24.7 +/- 8.5, 18.9 +/- 4.8, 17.4 +/- 5.7, and 12.2 +/- 7.2, respectively (p = 0.003). The median time (days) after admission to the onset of nosocomial CDD (first positive assay) for each study year was 14.5, 13.0, 12.0, and 13.0, respectively.

CONCLUSIONS

Although not all of the underlying assumptions of the method have been verified, the similarity of the findings in the present study to those of previously published studies of nosocomial CDD suggests that the method is valid. Alternatives to traditional methods of performing nosocomial infection surveillance need to be developed so that infection control practitioners can focus more of their efforts on prevention activities.

Simultaneous outbreaks of two strains of toxigenic Clostridium difficile in a general hospital

We report an outbreak of Clostridium difficile-associated disease (CDAD) in a large Dublin hospital. From January to June 1995, inclusive, 139 patients were affected; the mean age of cases was 68.8 +/- 19 years. Clinical information is available for 73 cases identified during the first four months of the outbreak. The majority of patients presented with abrupt onset of watery diarrhoea; however, 19.2% presented with an unexplained pyrexia following a course of antimicrobial therapy and 5.5% presented with a surgical acute abdomen. Twenty patients (27.4%) experienced relapsing disease and seven (9.6%) patients died. Seventy-six percent of cases received a cephalosporin prior to the onset of disease, the highest relative risks occurring with third-generation agents; however, 9.6% of patients affected had not been exposed to antimicrobial therapy in the preceding eight weeks. Pyrolysis mass spectrometry identified two clusters of isolates, representing two strains of C. difficile. There was marked spatial clustering of these strains, with each confined to a separate area of the hospital. Infection control measures and an antibiotic policy were introduced. Throughout the outbreak period the use of the most frequently used cephalosporin in the hospital increased; this was accompanied paradoxically by a reduction in the number of new cases of CDAD.

Comparison of cycloserine-cefoxitin-fructose agar (CCFA) and taurocholate-CCFA for recovery of Clostridium difficile during surveillance of hospitalized patients

The effectiveness of cycloserine-cefoxitin-fructose agar (CCFA) and taurocholate-CCFA (TCCFA) in isolating Clostridium difficile from swabs of the rectum or stools from 184 hospitalized patients who were monitored weekly and when they had diarrhea was compared. The number of surveillance time points ranged from two to eight per patient over a period of 4 to 34 days per patient, totalling 621 comparisons of the media. C. difficile was isolated more frequently by TCCFA than CCFA at seven of eight surveillance points, a significant trend (O'Brien test, p = 0.002). This difference reached statistical significance at the second surveillance time point when the prevalence of C. difficile was sufficiently high. At the second surveillance point, C. difficle was isolated only by TCCFA in 7 of 184 comparisons of the media, only by CCFA in none of the comparisons, and by both media in 19 comparisons (p = 0.016). C. difficle was first isolated at an earlier surveillance time point on TCCFA in 11 of 36 patients and on CCFA first only once (p = 0.005). Use of TCCFA media increased the rapidity and sensitivity of culture for C. difficle when doing patient surveillance but did not increase sensitivity when diagnosing patients with diarrhea.

Magnitude and prevention of nosocomial infections in the intensive care unit

Nosocomial infections among intensive care unit (ICU) patients usually are related to the use of invasive devices (e.g., mechanical ventilators, urinary catheters, or central venous catheters). This article discusses the impact of these devices and other risk factors for nosocomial infection in ICU patients. Data on etiologic pathogens and device-related infection rates from the National Nosocomial Infection Surveillance System are presented, general infection control guidelines for ICUs are reviewed, and special infection control problems encountered in ICUs are discussed.