Fecal leukocytes in stool specimens submitted for Clostridium difficile toxin assay

Does this patient have Clostridioides difficile infection? A systematic review and meta-analysis

BACKGROUND

The clinical features and predictors of Clostridioides difficile infection overlap with many conditions.

OBJECTIVES

We performed a systematic review to evaluate the diagnostic utility of clinical features (clinical examination, risk factors, laboratory tests, and radiographic findings) associated with C. difficile.

METHODS

Systematic review and meta-analysis of diagnostic features for C. difficile.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, and Cochrane databases were searched up to September 2021.

STUDY ELIGIBILITY CRITERIA

Studies that reported clinical features of C. difficile, a valid reference standard test for confirming diagnosis of C. difficile, and a comparison among patients with a positive and negative test result.

PARTICIPANTS

Adult and paediatric patients across diverse clinical settings.

OUTCOMES

Sensitivity, specificity, likelihood ratios.

REFERENCE STANDARD

Stool nucleic acid amplification tests, enzyme immunoassays, cell cytotoxicity assay, and stool toxigenic culture.

ASSESSMENT OF RISK OF BIAS

Rational Clinical Examination Series and Quality Assessment of Diagnostic Accuracy Studies-2.

METHODS OF DATA SYNTHESIS

Univariate and bivariate analyses.

RESULTS

We screened 11 231 articles of which 40 were included, enabling the evaluation of 66 features for their diagnostic utility for C. difficile (10 clinical examination findings, 4 laboratory tests, 10 radiographic findings, prior exposure to 13 antibiotic types, and 29 clinical risk factors). Of the ten features identified on clinical examination, none were significantly clinically associated with increased likelihood of C. difficile infection. Some features that increased likelihood of C. difficile infection were stool leukocytes (LR+ 5.31, 95% CI 3.29-8.56) and hospital admission in the prior 3 months (LR+ 2.14, 95% CI 1.48-3.11). Several radiographic findings also strongly increased the likelihood of C. difficile infection like ascites (LR+ 2.91, 95% CI 1.89-4.49).

DISCUSSION

There is limited utility of bedside clinical examination alone in detecting C. difficile infection. Accurate diagnosis of C. difficile infection requires thoughtful clinical assessment for interpretation of microbiologic testing in all suspected cases.

Screening for gastrointestinal and pancreatic diseases

Diagnosis of chronic gastrointestinal and pancreatic diseases is challenging because patients generally present with nonspecific symptoms, such as abdominal pain and chronic diarrhea, some of which can last for many years. Although stool assays are more sensitive than serum assays, the former has unique limitations that healthcare providers should be aware of. One algorithm to screen for chronic gastrointestinal and pancreatic issues is to perform stool testing to assess inflammatory, watery (osmotic) and malabsorptive conditions. This chapter will discuss several stool-based screening tests, the major disorders they screen for and clinical performance. Sections on assay and sample limitations are also included. Stool testing can provide valuable diagnostic, prognostic and treatment response information if both the laboratory and clinician understand the benefits and limitations of these assays.

Clostridium difficile infection: management strategies for a difficult disease

Clostridium difficile was first described as a cause of diarrhea in 1978 and in the last three decades has reached an epidemic state with increasing incidence and severity in both healthcare and community settings. There also has been a rise in severe outcomes from C. difficile infection (CDI). There have been tremendous advancements in the field of CDI with the identification of newer risk factors, recognition of CDI in populations previously thought not at risk and development of better diagnostic modalities. Several treatment options are available for CDI apart from metronidazole and vancomycin, and include new drugs such as fidaxomicin and other options such as fecal microbiota transplantation. This review discusses the epidemiology, risk factors and outcomes from CDI, and focuses primarily on existing and evolving treatment modalities.

Clinical update for the diagnosis and treatment of Clostridium difficile infection

Clostridium difficile infection (CDI) presents a rapidly evolving challenge in the battle against hospital-acquired infections. Recent advances in CDI diagnosis and management include rapid changes in diagnostic approach with the introduction of newer tests, such as detection of glutamate dehydrogenase in stool and polymerase chain reaction to detect the gene for toxin production, which will soon revolutionize the diagnostic approach to CDI. New medications and multiple medical society guidelines have introduced changing concepts in the definitions of severity of CDI and the choice of therapeutic agents, while rapid expansion of data on the efficacy of fecal microbiota transplantation heralds a revolutionary change in the management of patients suffering multiple relapses of CDI. Through a comprehensive review of current medical literature, this article aims to offer an intensive review of the current state of CDI diagnosis, discuss the strengths and limitations of available laboratory tests, compare both current and future treatments options and offer recommendations for best practice strategies.

Is Fecal Leukocyte Test a good predictor of Clostridium difficile associated diarrhea?

Background

Fecal leukocyte test (FLT) is widely used to screen for invasive diarrheas including C. difficile associated diarrhea (CDAD), which account for more than 25 % of all antibiotic associated diarrhea.

Method

263 stool samples from patients with suspected CDAD were studied simultaneously for fecal leukocyte test (FLT) and Clostridium difficile toxin assay (CDTA). FLT was performed by the Giemsa technique and CDTA was performed by enzyme immuno assay (EIA).

Results

Sensitivity, specificity, positive predictive value and negative predictive value of FLT as compared to CDTA were 30%, 74.9%, 13.2% and 89.3% respectively.

Conclusion

Considering the poor sensitivity of FLT, and the comparable cost and time of obtaining a CDTA at our institution, we conclude that FLT is not a good screening test for CDAD. Possible reasons for FLT being a poor predictor of CDTA are discussed.

Infectious diarrhea

Infectious diarrhea is an extremely common illness that affects millions of Americans annually. For most patients, the illness is a self-limited one. Its major risk is dehydration. However, for some patients, diarrhea can lead to severe dehydration or be associated with bacteremia and metastatic infection. Patients with these conditions require prompt treatment. A large number of organisms have been associated with diarrhea in humans, and most laboratories routinely screen for Salmonella, Shigella, and Campylobacter. Other bacteria, parasites, and viruses account for a significant percentage of diarrhea cases and frequently go undetected. This article summarizes many of these pathogens and describes the settings in which they can be acquired. Food distribution networks have made the delivery of previously rare foods to remote areas a commonplace occurrence; this has also led to new challenges in the diagnosis and prevention of food-borne illnesses. Outbreaks of diarrhea now frequently extend across many states. The identification of a rare strain of a bacterial pathogen or changes in the isolation rate of common pathogens may be early clues to the cause of such an ongoing outbreak. Most enteric pathogens cause disease by either stimulating the secretion of fluids at the level of the small bowel or by irritating and invading the colon. Organisms that cause disease by the latter mechanism have the potential to invade the blood stream and spread to other parts of the body, including the bones and the central nervous system. Several organisms have been associated with specific postinfectious syndromes that are responsible for additional morbidity and mortality. The antibiotic resistance of bacterial pathogens has been increasing, and this has a limiting effect on the empiric treatment choices available for suspected bacterial diarrhea. Careful attention to local sensitivity patterns and appropriate testing of the patient's isolate are among the important factors that lead to successful treatment decisions.

Epidemiology, risk factors and treatments for antibiotic-associated diarrhea

Antibiotic-associated diarrhea (AAD) is a common complication of antibiotics and recent findings on the epidemiology, etiologies and treatment strategies are reviewed. Rates of AAD vary from 5 to 39% depending upon the specific type of antibiotic. The severity of AAD may include uncomplicated diarrhea, colitis or pseudomembranous colitis. The pathogenesis of AAD may be mediated through the disruption of the normal flora and overgrowth of pathogens or through metabolic imbalances. The impact of AAD is reflected by increased hospital stays, higher medical costs and increased rates of comorbidity. The key to decreasing these consequences is prompt diagnosis followed by effective treatment and institution of control measures.

Utility of a rapid fecal latex agglutination test detecting the neutrophil protein, lactoferrin, for diagnosing inflammatory causes of chronic diarrhea

OBJECTIVE

The utility of tests for fecal neutrophils in the setting of chronic diarrhea has not been established. The purpose of this study was to determine the causes of chronic diarrhea associated with fecal neutrophils.

METHODS

One fecal specimen from each of 10 normal subjects, 26 patients with known microscopic colitis, 13 with celiac sprue, eight with Crohn's disease, four with ulcerative colitis, and 103 with chronic diarrhea of unknown origin, as well as 10 fecal specimens from a patient with chronic nongranulomatous enterocolitis were analyzed blindly for the presence of a neutrophil granule protein called lactoferrin using a commercial latex agglutination kit. Diagnostic evaluation of the 103 patients with chronic diarrhea was carried out to determine the diagnostic accuracy of this test for chronic inflammatory bowel disease.

RESULTS

None of the normal control subjects, three of 39 patients with microscopic colitis or celiac sprue, all 10 specimens from the patient with enterocolitis, and all 12 control patients with ulcerative colitis or Crohn's disease had a positive fecal lactoferrin test. Eleven of 103 patients with chronic diarrhea presenting without a diagnosis had a positive test, and all were diagnosed with an inflammatory condition of the colon (five-, ulcerative colitis; four-, Crohn's disease; one-, ischemic colitis; and one-, microscopic colitis). Only one patient with inflammatory bowel disease had a negative lactoferrin test. The sensitivity, specificity, and positive and negative predictive values of the fecal lactoferrin test for ulcerative or Crohn's colitis were 90%, 98%, 82%, and 99%, respectively.

CONCLUSION

The major cause of fecal neutrophils in patients with chronic diarrhea is chronic inflammatory bowel disease of the colon. The latex agglutination test for fecal lactoferrin offers a highly sensitive, specific, and simple means for detection of fecal neutrophils in these patients.

Fecal lactoferrin, interleukin-1beta, and interleukin-8 are elevated in patients with severe Clostridium difficile colitis

Twenty-two patients with Clostridium difficile colitis as determined by positive enzyme immunoassay for toxin A were evaluated for fecal inflammatory markers and their relationship to the severity of illness. Fourteen of 22 specimens were positive for fecal lactoferrin (FLF), with titers from 1:50 to 1:800. Nine of 10 stools tested had ratios of interleukin-1beta (IL-1beta) to IL-1 receptor antagonist (IL-1ra) of >0.01. Seventeen of 22 specimens also had elevated IL-8 concentrations, and 12 of 14 had elevated IL-1beta concentrations. A review of the 18 available patient records revealed that fecal IL-8 concentrations, IL-1beta/IL-1ra ratios, and FLF titers were significantly higher in patients with moderate to severe disease than in patients with mild disease. These findings suggest that the proinflammatory effects of C. difficile may directly influence clinical characteristics of human disease.

Role of stool screening tests in diagnosis of inflammatory bacterial enteritis and in selection of specimens likely to yield invasive enteric pathogens

The Leuko-Test yielded a negative predictive value of 98.4% when it was used to screen 325 patients for inflammatory bacterial enteritis and a negative predictive value of 99.4% when it was used to screen 416 stool specimens for those from which enteric pathogens would likely be recovered when cultured. Neither microscopy for fecal leukocytes nor an assay for fecal occult blood, alone or in combination, allowed for the reliable detection of invasive bacterial enteritis or the reliable selection of specimens for culture. When positive in the Leuko-Test, specimens collected from patients after the third day of hospitalization did not yield enteric pathogens when the specimens were cultured, and specimens collected from inpatients within the first 3 days of hospitalization or from outpatients did not contain Clostridium difficile toxin A. As a screening test, the Leuko-Test has the ability to generate rapidly a result which can support the presumptive diagnosis of inflammatory bacterial enteritis or which can be used to determine the suitability of stool specimens for bacteriologic culture.

Clostridium difficile infection

The spore-forming anaerobe Clostridium difficile has become a serious enteropathogen. Changes in the composition of natural intestinal flora, mainly due to antibiotic therapy, permit its colonization of, and multiplication in, the colon. The disease is caused by (entero)toxin A and (cyto)toxin B, and infection ranges from asymptomatic carrier state and mild diarrhea to pseudomembranous colitis. The clinical diagnosis is made by observing inflammatory, sometimes bloody, diarrhea and by the colonoscopic detection of epithelial necrosis, ulceration, and, in the advanced state, pseudomembrane formation. The laboratory supports the diagnosis by detecting toxin A and/or B by an enzyme-linked immunoassay with high specificity, but sometimes less sensitivity than with the cytotoxin assay in tissue culture cells. Fecal leukocytes or fecal lactoferrin may be found. Culture for the isolation and identification of toxigenic C. difficile is time consuming but necessary for epidemiological studies. Polymerase chain reaction (PCR) tests have been tested for detection of the toxin B gene directly in stool. Therapy consists of stopping all systemic antibiotic treatment and the use of oral metronidazole or vancomycin. There may be more relapses after vancomycin therapy, and the increasing vancomycin resistance of Enterococcus is worrisome. Prevention, especially of nosocomial spread, requires isolation and enforced handwashing. For epidemiological studies, the bacteria can be typed by molecular DNA analyses, including PCR, protein electrophoresis, and immunological tests.

Application of rejection criteria for stool cultures for bacterial enteric pathogens

Over 20 months, we prospectively assessed the yield of cultures for Salmonella, Shigella, and Campylobacter spp. from adults and children. In the first 10 months, 53% (567 of 1,097) of specimens from adults were from patients who had been in the hospital for > 3 days. Overall, only 2.6% (29 of 1,097) of specimens contained pathogens, and all were from patients who had been in the hospital for < or = 3 days. Over the second 10 months, specimens from adults in the hospital for > 3 days were not cultured unless special reasons existed. Thirty percent (368 of 1,229) of specimens were rejected. Concurrently, 7.5% (51 of 677) of stool specimens from children were positive. Only one positive specimen came from a child who had been in the hospital for > 3 days. Neither stool consistency nor fecal leukocytes were useful predictors for the presence of an enteric pathogen. We recommend that specimens from both adults and children in the hospital for > 3 days not be cultured unless there are delineated plausible clinical or epidemiological reasons to do so.