Fecal leukocyte stain has diagnostic value for outpatients but not inpatients

Diagnostic Guidance for C. difficile Infections

Diagnosis of Clostridioides difficile infection (CDI) can be challenging. First of all, there has been debate on which of the two reference assays, cell cytotoxicity neutralization assay (CCNA) or toxigenic culture (TC), should be considered the gold standard for CDI detection. Although the CCNA suffers most from suboptimal storage conditions and subsequent toxin degradation, TC is reported to falsely increase CDI detection rates as it cannot differentiate CDI patients from patients asymptomatically colonised by toxigenic C. difficile. Several rapid assays are available for CDI detection and fall into three broad categories: (1) enzyme immunoassays for glutamate dehydrogenase, (2) enzyme immunoassays or single-molecule array assays for toxins A/B and (3) nucleic acid amplification tests detecting toxin genes. All three categories have their own limitations, being suboptimal specificity and/or sensitivity or the inability to discern colonised patients from CDI patients. In light of these limitations, multi-step algorithmic testing has been advocated by international guidelines (IDSA/SHEA and ESCMID) in order to optimize diagnostic accuracy. As a result, a survey performed in 2018-2019 in Europe revealed that most of all hospital sites reported using more than one test to diagnose CDI. CDI incidence rates are also influenced by sample selection criteria, as several studies have shown that if not all unformed stool samples are tested for CDI, many cases may be missed due to an absence of clinical suspicion. Since methods for diagnosing CDI remain imperfect, there has been a growing interest in alternative testing strategies like faecal microbiota biomarkers, immune modulating interleukins, cytokines and imaging methods. At the moment, these alternative methods might play an adjunctive role, but they are not suitable to replace conventional CDI testing strategies.

Investigation into the Photochemical Properties of Methylene Blue-Immobilized Hydroxyapatite Nanoparticles for Theranostic Application

In the biomedical field, there has been a requirement for developing theranostic nanomaterials with higher biosafety, leading to both diagnosis and therapy. Methylene blue (MB⁺) is an organic dye with both photoluminescence (PL) and photosensitization abilities to generate singlet oxygen (¹O₂). However, MB⁺ easily loses its generation ability by hydrogen reduction in vivo or by forming aggregates. In this study, MB⁺ immobilized on biocompatible hydroxyapatite (HA) nanoparticles was applied for the bifunctions of efficient PL and photosensitization. The MB⁺-immobilized HA nanoparticles (MH) formed aggregates with sizes of 80-100 nm in phosphate buffer (PB). The generation amount and efficiency of ¹O₂ from the nanoparticles in PB seem to depend on the immobilized MB⁺ amount and the percentage of the monomer, respectively. Considering the larger immobilized amount and percentage of the MB⁺ monomer, it was found that there was MH with the lower generation amount and efficiency of ¹O₂ to exhibit the highest PL intensity. The photofunctional measurement of MB⁺ revealed the state of MB⁺ molecules on the HA surface, and it was suggested that the MB⁺ molecules immobilized on the MH surface would form more hydrogen bonds to change their excitation states. In the cellular experiments, the Hela cancer cells reacted with the nanoparticles and showed red-color PL, indicating cellular imaging. Furthermore, the adherent cell coverage decreased by ¹O₂ generation, indicating the importance of the immobilization amount of the MB⁺ monomer. Therefore, theranostic nanomaterials with biosafety were successfully synthesized to show two photofunctions, which provide both cellular imaging and photodynamic therapy by the nanohybrid system between HA and MB⁺.

The other Campylobacters: Not innocent bystanders in endemic diarrhea and dysentery in children in low-income settings

Background

Campylobacter is one of the main causes of gastroenteritis worldwide. Most of the current knowledge about the epidemiology of this food-borne infection concerns two species, C. coli and C. jejuni. Recent studies conducted in developing countries and using novel diagnostic techniques have generated evidence of the increasing burden and importance of other Campylobacter species, i.e. non-C. coli/jejuni. We performed a nested case-control study to compare the prevalence of C. coli/jejuni and other Campylobacter in children with clinical dysentery and severe diarrhea as well as without diarrhea to better understand the clinical importance of infections with Campylobacter species other than C. coli/jejuni.

Methodology/Principal findings

Our nested case-control study of 439 stool samples included dysenteric stools, stools collected during severe diarrhea episodes, and asymptomatic stools which were systematically selected to be representative of clinical phenotypes from 9,160 stools collected during a birth cohort study of 201 children followed until two years of age. Other Campylobacter accounted for 76.4% of the 216 Campylobacter detections by qPCR and were more prevalent than C. coli/jejuni across all clinical groups. Other Campylobacter were also more prevalent than C. coli/jejuni across all age groups, with older children bearing a higher burden of other Campylobacter. Biomarkers of intestinal inflammation and injury (methylene blue, fecal occult test, myeloperoxidase or MPO) showed a strong association with dysentery, but mixed results with infection. MPO levels were generally higher among children infected with C. coli/jejuni, but Shigella-infected children suffering from dysentery recorded the highest levels (26,224 ng/mL); the lowest levels (10,625 ng/mL) were among asymptomatic children infected with other Campylobacter. Adjusting for age, sex, and Shigella infection, dysentery was significantly associated with C. coli/jejuni but not with other Campylobacter, whereas severe diarrhea was significantly associated with both C. coli/jejuni and other Campylobacter. Compared to asymptomatic children, children suffering from dysentery had a 14.6 odds of C. coli/jejuni infection (p-value < 0.001, 95% CI 5.5–38.7) but were equally likely to have other Campylobacter infections–odds ratio of 1.3 (0.434, 0.7–2.4). Children suffering from severe diarrhea were more likely than asymptomatic children to test positive for both C. coli/jejuni and other Campylobacter–OR of 2.8 (0.034, 1.1–7.1) and 1.9 (0.018, 1.1–3.1), respectively. Compared to the Campylobacter-free group, the odds of all diarrhea given C. coli/jejuni infection and other Campylobacter infection were 8.8 (<0.001, 3.0–25.7) and 2.4 (0.002, 1.4–4.2), respectively. Eliminating other Campylobacter in this population would eliminate 24.9% of the diarrhea cases, which is almost twice the population attributable fraction of 15.1% due to C. coli/jejuni.

Conclusions/Significance

Eighty-seven percent of the dysentery and 59.5% of the severe diarrhea samples were positive for Campylobacter, Shigella, or both, emphasizing the importance of targeting these pathogens to limit the impact of dysentery and severe diarrhea in children. Notably, the higher prevalence of other Campylobacter compared to C. coli/jejuni, their increasing burden during early childhood, and their association with severe diarrhea highlight the importance of these non-C. coli/jejuni Campylobacter species and suggest a need to clarify their importance in the etiology of clinical disease across different epidemiological contexts.

Campylobacter is a major public health concern in developed and developing countries. C. coli and C. jejuni have long been considered to be the major disease-causing species, and clinical microbiologic approaches target these two species. However, less selective diagnostic approaches have shown the increasing importance of other Campylobacter species (i.e. non-C. coli/jejuni). Our case-control study investigated the association between diarrhea, C. coli/jejuni, and other Campylobacter among 439 stool samples from 201 children in peri-urban communities in Loreto, Peru. Three quarters of the 216 Campylobacter detections were associated with other Campylobacter, whose prevalence increased with age and was greater than that of C. coli/jejuni in all age and clinical groups (dysentery, severe diarrhea, and asymptomatic). Despite their lower prevalence, C. coli/jejuni were more strongly associated with higher levels of myeloperoxidase, clinical dysentery, and the presence of leukocytes and blood in the stool compared to other Campylobacter. Other Campylobacter were equally likely as C. coli/jejuni to be detected in severe diarrhea cases–odds ratio of 1.9 (p-value = 0.018, 95% CI 1.1–3.1) and 2.8 (0.034, 1.1–7.1), respectively. Removing C. coli/jejuni in this population would eliminate 15.1% of diarrhea compared to 24.9% if other Campylobacter were eliminated.

A prospective cross sectional study of detection of Clostridium difficile toxin in patients with antibiotic associated diarrhoea

BACKGROUND AND OBJECTIVES

Clostridium difficile infections (CDI) include self-limiting antibiotic associated diarrhoea (AAD), antibiotic-associated colitis, and pseudomembranous colitis. The present study aimed at detecting C. difficile toxin in stool samples of patients with AAD and analyzing the antibiotic use and presence of other risk factors in these patients.

MATERIALS AND METHODS

In this study, which was conducted on 660 samples, a 2- step strategy was used. In the first step, glutamate dehydrogenase (GDH) was detected in stool samples by enzyme-linked immunofluorescent assay (ELFA). In the second step, GDH positive samples were tested for C. difficile toxin A and B by ELFA. Nucleic acid amplification test (NAAT) was also performed on few samples that were found to be GDH positive and toxin negative or equivocal by ELFA.

RESULTS

Of the 660 samples screened, toxin was detected in 8.8% (58/660) by ELFA and 9.7% (64/660) by NAAT. GDH was detected in 23.8% (157/660) and toxin in 36.9% (58/157) of the GDH positives. Most of the toxin positive patients were on one or more antibiotics prior to developing diarrhoea. The implicated antibiotics were meropenem, amikacin, colistin and cephalosporins. Diabetes, hypertension, use of proton pump inhibitors, previous hospitalization, malignancy and chemotherapy were found to be the risk factors in our study.

CONCLUSION

Prevalence of GDH was 23.8% (157/660) by ELFA. Toxin prevalence was 9.7% (64/660). Detection rates of C. difficile associated diarrhoea (CDAD) increased with inclusion of NAAT testing by ELFA.

Diagnostic Guidance for C. difficile Infections

Diagnosis of Clostridium difficile infection (CDI) can be challenging. First of all, there has been debate on which of the two reference assays, cell cytotoxicity neutralization assay (CCNA) or toxigenic culture (TC) should be considered the gold standard for CDI detection. Although the CCNA suffers most from suboptimal storage conditions and subsequent toxin degradation, TC is reported to falsely increase CDI detection rates as it cannot differentiate CDI patients from patients asymptomatically colonised by toxigenic C. difficile. Several rapid assays are available for CDI detection and fall into three broad categories: (1) enzyme immunoassays for glutamate dehydrogenase, (2) enzyme immunoassays for toxins A/B and (3) nucleic acid amplification tests detecting toxin genes. All three categories have their own limitations, being suboptimal specificity and/or sensitivity or the inability to discern colonised patients from CDI patients. In light of these limitations, multi-step algorithmic testing has now been advocated by international guidelines in order to optimize diagnostic accuracy. Despite these recommendations, testing methods between hospitals vary widely, which impacts CDI incidence rates. CDI incidence rates are also influenced by sample selection criteria, as several studies have shown that if not all unformed stool samples are tested for CDI, many cases may be missed due to an absence of clinical suspicion. Since methods for diagnosing CDI remain imperfect, there has been a growing interest in alternative testing strategies like faecal biomarkers, immune modulating interleukins, cytokines and imaging methods. At the moment, these alternative methods might play an adjunctive role, but they are not suitable to replace conventional CDI testing strategies.

2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea

These guidelines are intended for use by healthcare professionals who care for children and adults with suspected or confirmed infectious diarrhea. They are not intended to replace physician judgement regarding specific patients or clinical or public health situations. This document does not provide detailed recommendations on infection prevention and control aspects related to infectious diarrhea.

Diagnostic value of the Vesikari Scoring System for predicting the viral or bacterial pathogens in pediatric gastroenteritis

Purpose

To evaluate the diagnostic value of the Vesikari Scoring System (VSS) as an early predictor of pathogens in children with acute gastroenteritis (AG).

Methods

In this retrospective study, the VSS score, absolute neutrophil count (ANC), and C-reactive protein (CRP) levels were analyzed in 107 hospitalized children with AG, aged 6 months to 17 years. Patients were divided into nonspecific, viral, and bacterial groups according to the pathogens detected using a multiplex polymerase chain reaction (PCR) test.

Results

Patients in the bacterial group had significantly higher CRP values and VSS scores compared to those in the viral group and significantly higher VSS scores compared to those in the nonspecific group (P<0.05). Patients in the viral group had significantly higher VSS scores than those in the nonspecific group (P<0.05). Logistic regression analysis revealed that VSS was the most effective diagnostic tool for predicting the type of pathogen (P<0.05). The area under the receiver operating characteristics curve of VSS was significantly greater than that for ANC and CRP (P<0.05). At a cutoff point of 10 in the VSS, an acceptable diagnostic accuracy could be achieved for distinguishing between bacterial and viral pathogens in AG.

Conclusion

VSS can be considered a useful and reliable infectious marker for pediatric gastroenteritis. VSS may be a good early predictor of the type of pathogen, enabling development of a treatment plan before results from a stool culture or PCR test are available.

Markers of intestinal inflammation for the diagnosis of infectious gastroenteritis

Infectious diarrhea is a major cause of morbidity. A rapid and inexpensive assay for the diagnosis of infectious gastroenteritis would expedite appropriate therapy and prevent unnecessary and potentially invasive testing. This article summarizes assays for the diagnosis of infectious gastroenteritis based on the host response to bacterial, viral, or parasitic infection. This includes both systemic biomarkers (such as C-reactive protein, erythrocyte sedimentation rate, and serum cytokines) and fecal biomarkers (such as lactoferrin, fecal leukocyte analysis, and calprotectin). Although some of these assays have value as adjunct diagnostics, they lack sensitivity and specificity as stand-alone tests in this setting.

The evaluation of Clostridium difficile infection (CDI) in a community hospital

INTRODUCTION

Clostridium difficile is a serious reemerging pathogen in Europe and North America. C. difficile infection (CDI) has been of concern over the last decade in view of its significant morbidity and mortality, as well as the high health care costs involved with each case. Although multiple risk factors are known to be associated with CDI, a number of patients develop severe infection even in the absence of known risk factors. CDI is diagnosed by the detection of the toxin A/B in stools by enzyme immunoassay (EIA) or by polymerase chain reaction (PCR). There is conflicting literature regarding whether any particular group of antibiotics is associated with higher risk for CDI. There is also a tendency to perform repeated stool tests for toxin A/B if the first test is negative. We evaluated 100 consecutive hospitalized patients who tested positive for C. difficile over a one-year period.

METHODS

We performed a retrospective analysis of 100 consecutive patients with CDI admitted to our hospital between July 2008 and June 2009. Patient records were reviewed for risk factors, treatment, and clinical outcomes. We also evaluated the number of stool tests performed for the detection of C. difficile and fecal leukocyte testing in each patient.

RESULTS

The majority of the patients were more than 60 years of age (87%). Forty-four percent of patients presented from a nursing facility. More than 50% were on Proton Pump Inhibitors (PPIs) at the time of admission. Co-morbidities in our patients included malignancy in 28%, diabetes mellitus in 25%, and chronic renal disease in 23%. Most of the patients had multiple co-morbidities. Patients who had taken antibiotics in the previous six months constituted 74% of the total study population. A beta-lactam alone or in combination with other antibiotics was prescribed in 48%, quinolones in 13% and clindamycin in 4% of patients. Stool samples were tested only once in 53% of patients and twice or more in 43%. Metronidazole was the initial therapy in 86% of patients. Intensive care unit stay was required in 33% of patients. Seventeen percent died during their hospitalization.

CONCLUSIONS

Elderly patients are especially vulnerable to CDI when exposed to antibiotics, and higher mortality and morbidity is observed in this age group. PPI use was common in our patients. Metronidazole was used as the first line agent in the majority of patients. We also determined a tendency to test for the C. difficile toxin in more than one stool sample. All of these practices need to be modified based on the current guidelines.

Evaluation and treatment of colonic symptoms

Important considerations for constipation include: 1. Initial evaluation should evaluate for fecal incontinence, fecal impaction, medication side effects, concerning symptoms, underlying medical or metabolic issues and irritable bowel syndrome. 2. History and examination should be used to determine if a defecatory disorder is most likely. a. If defecatory disorder is likely, testing with balloon expulsion or anal manometry can be considered and, if confirmed, treatment with biofeedback (if testing not available, it is reasonable to trial fiber and laxatives because many patients have a mixed disorder). b. If it is unlikely, proceed with trial of fiber and/or osmotic laxatives. 3. If continued symptoms, consider trial of newer agent (lubiprostone or linaclotide). 4. If ineffective, consider testing for colon transit time and referral to gastroenterology.

Nosocomial diarrhea: evaluation and treatment of causes other than Clostridium difficile

Diarrhea is common among hospitalized patients but the causes are distinct from those of diarrhea in the community. We review existing data about the epidemiology of nosocomial diarrhea and summarize recent progress in understanding the mechanisms of diarrhea. Clinicians should recognize that most cases of nosocomial diarrhea have a noninfectious etiology, including medications, underlying illness, and enteral feeding. Apart from Clostridium difficile, the frequency of infectious causes such as norovirus and toxigenic strains of Clostridium perfringens, Klebsiella oxytoca, Staphylococcus aureus, and Bacteroides fragilis remains largely undefined and test availability is limited. Here we provide a practical approach to the evaluation and management of nosocomial diarrhea when tests for C. difficile are negative.

Fecal leukocytes in children infected with diarrheagenic Escherichia coli

The purpose of this study was to determine the presence and quantity of fecal leukocytes in children infected with diarrheagenic Escherichia coli and to compare these levels between diarrhea and control cases. We analyzed 1,474 stool samples from 935 diarrhea episodes and 539 from healthy controls of a cohort study of children younger than 2 years of age in Lima, Peru. Stools were analyzed for common enteric pathogens, and diarrheagenic E. coli isolates were studied by a multiplex real-time PCR. Stool smears were stained with methylene blue and read by a blinded observer to determine the number of polymorphonuclear leukocytes per high-power field (L/hpf). Fecal leukocytes at >10 L/hpf were present in 11.8% (110/935) of all diarrheal episodes versus 1.1% (6/539) in controls (P < 0.001). Among stool samples with diarrheagenic E. coli as the only pathogen isolated (excluding coinfection), fecal leukocytes at >10 L/hpf were present in 8.5% (18/212) of diarrhea versus 1.3% (2/157) of control samples (P < 0.01). Ninety-five percent of 99 diarrheagenic E. coli diarrhea samples were positive for fecal lactoferrin. Adjusting for the presence of blood in stools, age, sex, undernutrition, and breastfeeding, enterotoxigenic E. coli (ETEC) isolation as a single pathogen, excluding coinfections, was highly associated with the presence of fecal leukocytes (>10 L/hpf) with an odds ratio (OR) of 4.1 (95% confidence interval [CI], 1.08 to 15.51; P < 0.05). Although diarrheagenic E. coli was isolated with similar frequencies in diarrhea and control samples, clearly it was associated with a more inflammatory response during symptomatic infection; however, in general, these pathogens elicited a mild inflammatory response.

Infectious diseases and the use of antibiotics in outpatients at the emergency department of the University Hospital of León, Nicaragua

BACKGROUND

In order to develop guidelines for the use of antimicrobial agents, it is necessary to obtain detailed information on the prevalence of infectious diseases and antibiotic usage.

METHODS

A retrospective study was conducted among outpatients with acute infections visiting the emergency department of the University Hospital of León, Nicaragua.

RESULTS

Over the course of one month, 2027 patients visited the emergency department. Seven hundred and thirty-two patients (36.1%) had an infection, with a total of 799 acute infections. The majority of patients (55.9%) were children. Respiratory tract infections (43.4%), urogenital infections (29.5%), and diarrhea or gastroenteritis of presumed infectious origin (8.8%) were the most frequent infections. Among respiratory tract infections, the most frequent diagnoses were community-acquired pneumonia (CAP; 31.4%), acute tonsillitis (28.2%), and the common cold (17.6%). CAP was treated with procaine benzylpenicillin in 70.6% of cases, whereas 84.0% of patients with acute tonsillitis were treated with a single dosage of benzathine benzylpenicillin intramuscularly. Among urogenital infections, the most frequent diagnosis was acute uncomplicated urinary tract infection (24.2%). Approximately a quarter of patients with uncomplicated urinary tract infections did not receive treatment according to the local guidelines. Of the patients with acute diarrhea, 27.1% were treated with antibiotics, while only a minority had leukocytes in Wright stain of the feces.

CONCLUSIONS

In conclusion our study shows that the use of antimicrobial agents is not optimal. Antibiotics were prescribed too often and not according to the local guidelines. This will further exacerbate the resistance problem in Nicaragua.

A Bayesian approach to acute infectious diarrhea in adults

Acute infectious diarrhea is a yearly occurrence for most Americans, and is associated with 1 million hospitalizations and about 6000 deaths in the United States annually. Up to 80% of acute infectious diarrhea is caused by noroviruses, which produce a clinically mild illness with a predictable short course and good outcome that make laboratory testing and antimicrobial treatment unnecessary. Most diarrhea-causing bacteria and protozoa can cause a clinical illness "like norovirus"; when they do so in healthy adults neither specialized testing nor antimicrobials is required. The presence or absence of epidemiologic evidence (such as travel, hospitalization, antibiotic use, other exposures)and clinical evidence (such as diarrhea frequency and duration, severity of abdominal pain and fever, character of stool, presence of chronic illness or immune deficiency) can change the probability of "not norovirus" from as low as 8% to as high as 100%. Such probabilities guide the use of laboratory testing and antimicrobial therapy in patients who have acute infectious diarrhea.

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.

Performance assessment of the fecal leukocyte test for inpatients

Traditionally, fecal leukocyte testing detects large bowel inflammation or disruption, conditions that allow leukocytes into the stool. However, test usefulness with inpatients is unclear. Two hundred five inpatients who had undergone one to three tests were identified, and their FLT results were compared to their gastrointestinal disease diagnoses at time of discharge. A specificity of 92% for detecting intact colonic mucosae in inpatients was found.

Diagnostic accuracy of stool assays for inflammatory bacterial gastroenteritis in developed and resource-poor countries

Because acute bacterial gastroenteritis is often inflammatory, rapid stool assays that detect intestinal inflammation might be used to distinguish between bacterial and nonbacterial gastroenteritis. We performed meta-analyses to determine the discriminatory power, in developed and in resource-poor countries, of rapid stool assays that test for lactoferrin, fecal leukocytes, fecal erythrocytes, and occult blood. In developed countries, the area under the summary receiver operating characteristic curve (AUC/SROC) was 0.89 for fecal leukocytes and 0.81 for occult blood. In resource-poor countries, the AUC/SROC was 0.79 for lactoferrin, 0.72 for fecal leukocytes, 0.63 for occult blood, and 0.61 for fecal erythrocytes. In developed countries, positive and negative likelihood ratios (LR+ and LR-, respectively) for fecal leukocytes were 4.56 and 0.32 when a threshold of >5 cells/high-power field was used, compared with 2.94 and 0.6 in resource-poor countries; for lactoferrin, LR+ was 1.34 and LR- was 0.17 in resource-poor countries when the threshold was an agglutination rating of "+" and a dilution of 1:50. In developing countries, rapid stool assays performed poorly, whereas in developed countries, tests for fecal leukocytes, lactoferrin, and occult blood were moderately useful and could identify patients who were more likely to benefit from empirical antibiotic therapy.