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

The Role of Diagnostic Stewardship in Clostridioides difficile Testing: Challenges and Opportunities

PURPOSE OF REVIEW

Accurate and timely diagnosis of Clostridioides difficile infection (CDI) is imperative to prevent C. difficile transmission and reduce morbidity and mortality due to CDI, but CDI laboratory diagnostics are complex. The purpose of this article is to review the role of laboratory tests in the diagnosis of CDI, and the role of diagnostic stewardship in optimization of C. difficile testing.

RECENT FINDINGS

Results from C. difficile diagnostic tests should be interpreted with an understanding of the strengths and limitations inherent in each testing approach. Use of highly sensitive molecular diagnostic tests without accounting for clinical signs and symptoms may lead to over-diagnosis of CDI and increased facility CDI rates. Current guidelines recommend a two-step, algorithmic approach for testing. Diagnostic stewardship interventions, such as education, order sets, order search menus, reflex orders, hard and soft stop alerts, electronic references, feedback and benchmarking, decision algorithms, and predictive analytics may help improve use of C. difficile laboratory tests and CDI diagnosis. The diagnostic stewardship approaches with the highest reported success rates include computerized clinical decision support (CCDS) interventions, face-to-face feedback, and real-time evaluations.

SUMMARY

CDI is a clinical diagnosis supported by laboratory findings. Together, clinical evaluation combined with diagnostic stewardship can optimize the accurate diagnosis of CDI.

Characteristics and Antibiotic Use Associated With Short-Term Risk of Clostridium difficile Infection Among Hospitalized Patients

OBJECTIVES

Polymerase chain reaction (PCR) has been shown to have an excellent sensitivity and specificity for the detection of Clostridium difficile infection (CDI). Little is known about risk factors for CDI within 14 days of an initial negative test. We sought to determine the characteristics among hospitalized patients associated with risk of short-term acquisition of CDI.

METHODS

A case-control study was conducted. Cases were patients who converted from PCR negative to positive within 14 days. Each case was matched with three controls. Conditional logistic regression was used to estimate the association between patient characteristics and CDI.

RESULTS

Of the 30 patients in our study who had a positive PCR within 14 days of a first negative PCR (cases), 15 (50%) occurred within 7 days of the initial test. Cases had a higher proportion of intravenous vancomycin use in the previous 8 weeks (odds ratio [OR], 3.38; 95% confidence interval [CI], 1.34-8.49) and were less likely to have recent antiviral agent use (OR, 0.30; 95% CI, 0.11-0.83) compared with controls.

CONCLUSIONS

In hospitalized patients, treatment with intravenous vancomycin within the prior 8 weeks of a first negative PCR test for C difficile is a risk factor for short-term risk for hospital-acquired CDI. Repeat testing guidelines for C difficile PCR should take into consideration patients who may be at high risk for short-term acquisition of CDI.

Clostridium difficile infection: risk factors, diagnosis and management

OPINION STATEMENT

Clostridium difficile infection (CDI) is the leading cause of death due to gastrointestinal infections in the US and is the most common cause of nosocomial diarrhea. The emergence of a hypervirulent strain in the early 2000s has been associated with a dramatic increase in the number and severity of cases in the US, Canada, and several other countries. Most cases are related to antibiotic use, but sporadic cases occur in otherwise healthy individuals with no risk factors. Morbidity and mortality are highest in the elderly. Diagnosis is confirmed by detection of C. difficile toxin in the stools. Treatment should be stratified by severity of disease, with metronidazole use for mild disease cases and vancomycin for severe disease. Recurrent CDI occurs in 10-20 % of cases. A first recurrence can be treated with a ten-day regimen of metronidazole or vancomycin; a second recurrence is best treated by a pulsed regimen of vancomycin. In patients with multiple (three or more) recurrences, fecal microbiota transplant has a high rate of success. The most important methods of prevention are wise antibiotic policies, hand hygiene, isolation, and barrier methods in hospital and long-term care facilities (LCTF) settings.

Clostridium difficile infection: prevention, treatment, and surgical management

Clostridium difficile is increasing in both incidence and severity. Although metronidazole and vancomycin remain the gold standard for medical management, and surgical colectomy the gold standard for surgical management, new treatment alternatives, including the creation of a diverting loop ileostomy along with colonic lavage and vancomycin enemas, are being investigated that may lead to changes in the current treatment algorithms. The most exciting development in the treatment options for C difficile infection, however, is likely to be novel immunologic agents, which hold the potential to reduce the incidence, mortality, and costs associated with C difficile.

Guidelines for diagnosis, treatment, and prevention of Clostridium difficile infections

Clostridium difficile infection (CDI) is a leading cause of hospital-associated gastrointestinal illness and places a high burden on our health-care system. Patients with CDI typically have extended lengths-of-stay in hospitals, and CDI is a frequent cause of large hospital outbreaks of disease. This guideline provides recommendations for the diagnosis and management of patients with CDI as well as for the prevention and control of outbreaks while supplementing previously published guidelines. New molecular diagnostic stool tests will likely replace current enzyme immunoassay tests. We suggest treatment of patients be stratified depending on whether they have mild-to-moderate, severe, or complicated disease. Therapy with metronidazole remains the choice for mild-to-moderate disease but may not be adequate for patients with severe or complicated disease. We propose a classification of disease severity to guide therapy that is useful for clinicians. We review current treatment options for patients with recurrent CDI and recommendations for the control and prevention of outbreaks of CDI.

Repeat stool testing for Clostridium difficile using enzyme immunoassay in patients with inflammatory bowel disease increases diagnostic yield

BACKGROUND

The incidence and severity of Clostridium difficile infection (CDI) in patients with inflammatory bowel disease (IBD) is increasing. CDI is diagnosed by toxin enzyme immunoassay (EIA) or real-time polymerase chain reaction (PCR) performed on stool samples. An earlier study evaluating EIA in IBD patients with CDI suggested that more than one stool sample be tested to increase diagnostic yield. We investigated whether repeat stool testing improves diagnostic accuracy for CDI in hospitalized IBD patients compared to hospitalized patients with CDI and no IBD.

METHODS

We performed retrospective data analysis from January 2005-May 2011 on 63,086 hospitalized patients who were tested for CDI using EIA or PCR. Of these, 2579 patients had IBD. Transition probabilities were calculated based on results from repeated tests.

RESULTS

Inclusive of all inpatients tested for CDI, 56,583 were tested using toxin EIA and 6503 were tested using PCR. In patients with no IBD, the first stool sample tested was positive in 90% and 94% with EIA and PCR respectively. In IBD patients tested using EIA, 101 were diagnosed with CDI. The first stool sample tested was positive in 81% of patients. Successive second and third stool samples yielded additional 14% and 5% CDI positive IBD patients.

CONCLUSIONS

Approximately one in five IBD patients with CDI required repeat testing to yield a positive result with EIA. There are minimal diagnostic gains of repeat testing by EIA or PCR in patients without IBD. We recommend repeat stool testing for CDI when using EIA to increase diagnostic yield in IBD patients.

Pathology consultation on detection of Clostridium difficile

Laboratory methods for detecting Clostridium difficile have undergone considerable evolution since the organism's etiologic association with antibiotic-associated diarrhea and colitis was established. Clearly, familiarity with the advantages and shortcomings of the various assays is essential for the laboratory director when choosing among these tests. For the consulting pathologist, furthermore, an understanding of the laboratory's role in securing a diagnosis of C difficile infection (CDI) is also required to identify requests for unnecessary testing that may be costly and potentially misleading. The purpose of this article is to highlight the major differences in laboratory test methods for CDI and to review a few commonly encountered provider ordering scenarios.

Repeat stool testing to diagnose Clostridium difficile infection using enzyme immunoassay does not increase diagnostic yield

BACKGROUND & AIMS

Clostridium difficile infection (CDI) is a hospital-acquired infection with increasing incidence and severity. The most frequently used test to diagnose CDI is an enzyme immunoassay (EIA) for toxins A and B in stool samples. It is common to test 2 or more stool samples, based on the assumption that this detects CDI with greater sensitivity than analysis of 1 sample. We investigated whether repeat stool testing significantly improves the diagnostic yield for CDI.

METHODS

We performed a retrospective analysis of hospitalized patients who were tested for CDI using EIA. From year 2005 to 2008, 39,402 stool samples from 17,971 patients with 29,373 diarrhea episodes were tested. Transition probabilities were calculated based on results from repeated tests.

RESULTS

A total of 2692 diarrheal episodes (9.17%) were diagnosed with CDI. Based on results of 3 consecutive tests, 2675 (99.36%) were diagnosed with CDI. The first stool sample tested produced positive results for 90.7% of cases. When samples were tested consecutively, for the second and third time, an additional 6.6% and 2% patients had positive test results, respectively. If the first test result was negative, the probability of the second test result being positive was 2.7%. If the first 2 test results were negative, the probability of the third test result being positive was 2.3%.

CONCLUSIONS

In patients who had multiple stool samples tested for CDI by EIA, almost 91% were accurately diagnosed based on the results of a single stool sample alone. Subsequent testing yielded a positive result in only 8.6% of patients. We therefore recommend that repeat testing not be done on a routine basis because it does not significantly improve diagnostic yield.