Clinical practice. Acute infectious diarrhea

Comparison of the BD MAX enteric bacterial panel to routine culture methods for detection of Campylobacter, enterohemorrhagic Escherichia coli (O157), Salmonella, and Shigella isolates in preserved stool specimens

We compared the BD MAX enteric bacterial panel (EBP) to culture for the detection of Salmonella, Shigella, Campylobacter, and Shiga toxin-producing enterohemorrhagic Escherichia coli (EHEC) O157 in seeded stool samples. The EBP panel demonstrated superior sensitivity and reliably detected Salmonella, EHEC O157, Shigella, and Campylobacter at concentrations 1- to 2-log10 lower than those needed for culture detection.

When a healthy diet turns deadly

The health benefits of a high fiber diet (HFD) result in part from the action of metabolic end products made by gut commensals on the host epithelium. Butyrate is one such beneficial metabolite; however, butyrate paradoxically enhances the capacity of Escherichia coli-produced Shiga toxin type 2 (Stx2) to kill tissue culture cells. We recently showed that mice fed an HFD exhibited increased butyrate in gut contents and had an altered intestinal microbiota with reduced numbers of Escherichia species. Furthermore, mice fed an HFD and infected with Stx-producing E. coli (STEC) were colonized to a higher degree, lost more weight and succumbed to infection at greater rates compared with STEC-infected low fiber diet animals. The HFD animals showed higher levels of the Stx receptor globotriaocylceramide (Gb3) in both the gut and kidneys. We speculate that an HFD that leads to increased intestinal butyrate and Gb3 in the intestines and kidneys may explain the higher rate of the hemolytic uremic syndrome in females over males.

Foodborne disease outbreaks caused by Bacillus cereus, Clostridium perfringens, and Staphylococcus aureus--United States, 1998-2008

From 1998 to 2008, 1229 foodborne outbreaks caused by Bacillus cereus, Clostridium perfringens, and Staphylococcus aureus were reported in the United States; 39% were reported with a confirmed etiology. Vomiting was commonly reported in B. cereus (median, 75% of cases) and S. aureus outbreaks (median, 87%), but rarely in C. perfringens outbreaks (median, 9%). Meat or poultry dishes were commonly implicated in C. perfringens (63%) and S. aureus (55%) outbreaks, and rice dishes were commonly implicated in B. cereus outbreaks (50%). Errors in food processing and preparation were commonly reported (93%), regardless of etiology; contamination by a food worker was only common in S. aureus outbreaks (55%). Public health interventions should focus on these commonly reported errors to reduce the occurrence of outbreaks caused by B. cereus, C. perfringens, and S. aureus in the United States.

Is diurnal temperature range a risk factor for childhood diarrhea?

BACKGROUND

Previous studies have found that high and cold temperatures increase the risk of childhood diarrhea. However, little is known about whether the within-day variation of temperature has any effect on childhood diarrhea.

METHODS

A Poisson generalized linear regression model combined with a distributed lag non-linear model was used to examine the relationship between diurnal temperature range and emergency department admissions for diarrhea among children under five years in Brisbane, from 1st January 2003 to 31st December 2009.

RESULTS

There was a statistically significant relationship between diurnal temperature range and childhood diarrhea. The effect of diurnal temperature range on childhood diarrhea was the greatest at one day lag, with a 3% (95% confidence interval: 2%-5%) increase of emergency department admissions per 1°C increment of diurnal temperature range.

CONCLUSION

Within-day variation of temperature appeared to be a risk factor for childhood diarrhea. The incidence of childhood diarrhea may increase if climate variability increases as predicted.

Evaluation of adhesion properties and antibacterial activities of the infant gut commensal Bifidobacterium bifidum PRL2010

Bifidobacteria are extensively exploited by the food industry as health-promoting microorganisms. However, very little is known about the molecular mechanisms responsible for these beneficial activities, or the molecular players that sustain their ability to colonize and persist within the human gut. Here, we have investigated the enteric adaptation features of the gut commensal Bifidobacterium bifidum PRL2010, originally isolated from infant feces. This strain was able to survive under gastrointestinal challenges, while it was shown to adhere to human epithelial intestinal cell monolayers (Caco 2 and HT-29), thereby inhibiting adhesion of pathogenic bacteria such as Escherichia coli and Cronobacter sakazakii.

Role of antidiarrhoeal drugs as adjunctive therapies for acute diarrhoea in children

Acute diarrhoea is a leading cause of child mortality in developing countries. Principal pathogens include Escherichia coli, rotaviruses, and noroviruses. 90% of diarrhoeal deaths are attributable to inadequate sanitation. Acute diarrhoea is the second leading cause of overall childhood mortality and accounts for 18% of deaths among children under five. In 2004 an estimated 1.5 million children died from diarrhoea, with 80% of deaths occurring before the age of two. Treatment goals are to prevent dehydration and nutritional damage and to reduce duration and severity of diarrhoeal episodes. The recommended therapeutic regimen is to provide oral rehydration solutions (ORS) and to continue feeding. Although ORS effectively mitigates dehydration, it has no effect on the duration, severity, or frequency of diarrhoeal episodes. Adjuvant therapy with micronutrients, probiotics, or antidiarrhoeal agents may thus be useful. The WHO recommends the use of zinc tablets in association with ORS. The ESPGHAN/ESPID treatment guidelines consider the use of racecadotril, diosmectite, or probiotics as possible adjunctive therapy to ORS. Only racecadotril and diosmectite reduce stool output, but no treatment has yet been shown to reduce hospitalisation rate or mortality. Appropriate management with validated treatments may help reduce the health and economic burden of acute diarrhoea in children worldwide.

Infection of cattle with Cryptosporidium parvum: mast cell accumulation in small intestine mucosa

Mast cells might play an important role as the major effector cells in the immune response against Cryptosporidium parvum. C. parvum is a protozoan parasite that causes cryptosporidiosis in animals and humans worldwide. To investigate the interaction between C. parvum and mast cells during infection, nine 3-day-old male calves were orally challenged with 10(6) oocysts of C. parvum per calf. The distribution of mast cells in the mucosa of the small intestine was analyzed by toluidine blue staining. The concentrations of histamine and the cytokines interferon-γ, interleukin-4, interleukin-2, and interleukin-12 were measured in the serum, and the histamine levels were also determined from the intestinal contents. The following clinical signs were monitored: nausea, watery diarrhea, dehydration, and weight loss. Oocysts were shed in the feces during the infection period. C. parvum infection induced an increase in mast cell numbers in the mucosa of the small intestine in distinct temporal and spatial patterns. Infection with C. parvum can induce mastocytosis in the entire small intestinal mucosa in immune-competent calves, and the presence of the parasites influences the distribution profile of the mast cells.

Interpretation and Relevance of Advanced Technique Results

Advanced techniques in the field of diagnostic microbiology have made amazing progress over the past two decades due largely to a technological revolution in the molecular aspects of microbiology [1, 2]. In particular, rapid molecular methods for nucleic acid amplification and characterization combined with automation and user-friendly software have significantly broadened the diagnostic capabilities of modern clinical microbiology laboratories. Molecular methods such as nucleic acid amplification tests (NAATs) rapidly are being developed and introduced in the clinical laboratory setting. Indeed, every section of the clinical microbiology laboratory, including bacteriology, mycology, mycobacteriology, parasitology, and virology, have benefited from these advanced techniques. Because of the rapid development and adaptation of these molecular techniques, the interpretation and relevance of the results produced by such molecular methods has lagged somewhat behind. The purpose of this chapter is to review and discuss the interpretation and relevance of results produced by these advanced molecular techniques. Moreover, this chapter will address the “myths” of NAATs, as these myths can markedly influence the interpretation and relevance of these results.

Funktions- und Laboruntersuchungen

Zur Analyse abgeatmeter Gase muss endexspiratorische Luft gewonnen werden, ohne Vermischung mit frühexspiratorischer Luft (sonst Korrektur mit Messung des CO2-Partialdrucks, s. unten). Ältere Kinder blasen nach Anhalten der Atmung über 15 s durch tiefe Ausatmung über einen Strohhalm endexspiratorische Luft in ein Glasröhrchen, das dann luftdicht verschlossen wird (Vacutainer), oder über ein Mundstück oder eine Maske direkt in ein H2-Messgerät oder in Beutel. Bei Säuglingen und Kleinkindern kann mit einer Maske oder einer Sonde, die bis zum nasopharyngealen Übergang vorgeschoben wird, mit einer Spritze atemsynchron exspiratorische Luft abgesaugt und in Vacutainer oder direkt in das Messgerät eingegeben werden. In Vacutainern sind Proben über mehr als 30 Tage stabil und können auch zur Analyse verschickt werden.

[When should request a stool culture?]

A stool culture needs a medical prescription and is justified only in a case of clearly defined acute diarrhea. The clinical context must be suggestive of a bacterial etiology. The detection of the bacterial agents has to follow a well-defined strategy to optimize a rigorous prescription. Standardized stool culture is for patients treated in medical community practice and for patients hospitalized for less than 3 days. Clostridium difficile toxin testing is systematically performed in case of nosocomial diarrhea. Additional bacterial detections are limited to defined indications.

Use of multiplex real-time PCR for detection of common diarrhea causing protozoan parasites in Egypt

Diarrhea is an important cause of morbidity and mortality, worldwide. Giardia intestinalis, Cryptosporidium spp., and Entamoeba histolytica are the most common diarrhea-causing parasitic protozoa. Diagnosis of these parasites is usually performed by microscopy. However, microscopy lacks sensitivity and specificity. Replacing microscopy with more sensitive and specific nucleic acid based methods is hampered by the higher costs, in particular in developing countries. Multiplexing the detection of more than one parasite in a single test by real-time polymerase chain reaction (PCR) has been found to be very effective and would decrease the cost of the test. In the present study, stool samples collected from 396 Egyptian patients complaining of diarrhea along with 202 faecal samples from healthy controls were examined microscopically by direct smear method and after concentration using formol-ethyl acetate. Frozen portions of the same samples were tested by multiplex real-time for simultaneous detection of E. histolytica, G. intestinalis, and Cryptosporidium spp. The results indicate that among diarrheal patients in Egypt G. intestinalis is the most common protozoan parasite, with prevalence rates of 30.5 and 37.1 %, depending on the method used (microscopy vs. multiplex real-time PCR). Cryptosporidium spp. was detected in 1 % of the diarrheal patients by microscopy and in 3 % by real-time PCR. While E. histolytica/dispar was detected in 10.8 % by microscopy, less than one fifth of them (2 %) were found true positive for Entamoeba dispar by real-time PCR. E. histolytica DNA was not detected in any of the diarrheal patients. In comparison with multiplex real-time PCR, microscopy exhibited many false positive and negative cases with the three parasites giving sensitivities and specificities of 100 and 91 % for E. histolytica/dispar, 57.8 and 85.5 % for G. intestinalis, and 33.3 and 100 % for Cryptosporidium spp.

Clinical features of human salmonellosis caused by bovine-associated subtypes in New York

The objective of this study was to identify patient symptoms and case outcomes that were more likely to occur as a result of Salmonella infections caused by bovine-associated subtypes (isolates that matched contemporary bovine isolates from New York by serovar and pulsed-field gel electrophoresis pattern), as compared to salmonellosis caused by non-bovine-associated subtypes. Data were collected in 34 counties of New York that comprise the Foodborne Diseases Active Surveillance Network (FoodNet) catchment area of the Centers for Disease Control and Prevention Emerging Infections Program. Patients with specimen collection dates between March 1, 2008 and March 1, 2010 were included. Symptoms and outcomes of 40 cases infected with bovine-associated Salmonella subtypes were compared to those of 379 control-cases infected with Salmonella isolates that were not bovine-associated. Cases were significantly more likely to have invasive salmonellosis (odds ratio, 3.8; p-value=0.02), after adjusting for age group, gender, and race. In addition, there was a marginal association between case status and the presence of blood in the stool (p-value=0.1) while ill. These findings might have implications for patient management, as a history of consuming undercooked foods of bovine origin or having direct contact with cattle in the few days prior to illness could be useful for suggesting a more proactive diagnostic approach as well as close monitoring for the need to implement more aggressive therapy.

Culturing stool specimens for Campylobacter spp., Pennsylvania, USA

In 2010, we surveyed 176 clinical laboratories in Pennsylvania regarding stool specimen testing practices for enteropathogens, including Campylobacter spp. Most (96.3%) routinely test for Campylobacter spp. In 17 (15.7%), a stool antigen test is the sole method for diagnosis. We recommend that laboratory practice guidelines for Campylobacter spp. testing be developed.

The prevalence of hypoglycemia in children with vomiting or decreased oral intake and irritability

OBJECTIVE

This study aimed to estimate the prevalence of hypoglycemia in children younger than 5 years presenting to the emergency department with vomiting or decreased oral intake and irritability.

METHODS

Children aged 1 month to 5 years presenting to the emergency department with vomiting (twice or more) or decreased oral intake (>50%) during the past 24 hours and irritability as part of the history of present illness were enrolled. Capillary blood glucose was obtained at triage. Patients with glucose level higher than 3.0 mmol/L were considered normoglycemic. Patients with glucose level of 3.0 mmol/L or lower were re-triaged (acuity level increased by 1), and sent to a treatment room with the recommendation that our institution's hypoglycemia protocol be applied.

RESULTS

Of the 145 enrolled patients, 2 were hypoglycemic, for an estimated prevalence of 1.4%. The mean capillary blood glucose level was 5.4 mmol/L, and the range was 2.8 to 11.8 mmol/L. The average age of participants was 21 months, and 48.3% were female. Most were triaged category 4 or 5, and the most common discharge diagnoses were gastroenteritis, viral illness, and vomiting not yet diagnosed.

CONCLUSIONS

Hypoglycemia is a rare occurrence in all-comers younger than 5 years with vomiting or decreased oral intake, even with early signs of neuroglycopenia. Measuring the capillary glucose is better left to the discretion of the physician than as part of triage.

A tannic acid-based medical food, Cesinex(®), exhibits broad-spectrum antidiarrheal properties: a mechanistic and clinical study

BACKGROUND

The purpose of this investigation was to evaluate the efficacy and tolerability of a tannic acid-based medical food, Cesinex(®), in the treatment of diarrhea and to investigate the mechanisms underlying its antidiarrheal effect.

METHODS

Cesinex(®) was prescribed to six children and four adults with diarrhea. Patient records were retrospectively reviewed for the primary outcome. Cesinex(®) and its major component, tannic acid, were tested for their effects on cholera toxin-induced intestinal fluid secretion in mice. Polarized human gut epithelial cells (HT29-CL19A cells) were used to investigate the effects of tannic acid on epithelial barrier properties, transepithelial chloride secretion, and cell viability.

RESULTS

Successful resolution of diarrheal symptoms was reported in nine of ten patients receiving Cesinex(®). The treatment of HT29-CL19A cells with clinically relevant concentrations of tannic acid (0.01-1 mg/ml) significantly increased transepithelial resistance (TER) and inhibited the cystic fibrosis transmembrane conductance regulator (CFTR)-dependent or the calcium-activated Cl(-) secretion. Tannic acid could also improve the impaired epithelial barrier function induced by tumor necrosis factor alpha (TNFα) and inhibited the disrupting effect of TNFα on the epithelial barrier function in these cells. Cholera toxin (CTX)-induced mouse intestinal fluid secretion was significantly reduced by the administration of Cesinex(®) or tannic acid. Cesinex(®) has high antioxidant capacity.

CONCLUSIONS

Cesinex(®) demonstrates efficacy and a good safety profile in the treatment of diarrhea. The broad-spectrum antidiarrheal effect of Cesinex(®) can be attributed to a combination of factors: its ability to improve the epithelial barrier properties, to inhibit intestinal fluid secretion, and the high antioxidant capacity.

Salmonella infections: an update on epidemiology, management, and prevention

Salmonella species are a group of Gram-negative enterobacteria and known human pathogens in developing as well as industrialized countries. Despite significant advances in sanitation, provision of potable water, and highly controlled food chain surveillance, transmission of Salmonella spp. continues to affect communities, preferentially children, worldwide. This review summarizes updated concepts on typhoidal and non-typhoidal Salmonella infections, starting with a historical perspective that implicates typhoid Salmonella as a significant human pathogen since ancient times. We describe the epidemiology of this pathogen with emphasis on the most recent non-typhoidal Salmonella outbreaks in industrialized countries and continued outbreaks of typhoid Salmonella in underserved countries. An overview of clinical aspects of typhoid and non-typhoid infections in developing and industrialized countries, respectively, is provided, followed by a description on current treatment concepts and challenges treating multidrug-resistant Salmonella infections. We conclude with prevention recommendations, and recent research studies on vaccine prevention.

Rapid evolution of fluoroquinolone-resistant Escherichia coli in Nigeria is temporally associated with fluoroquinolone use

Background

Antibiotic resistance has necessitated fluoroquinolone use but little is known about the selective forces and resistance trajectory in malaria-endemic settings, where selection from the antimalarial chloroquine for fluoroquinolone-resistant bacteria has been proposed.

Methods

Antimicrobial resistance was studied in fecal Escherichia coli isolates in a Nigerian community. Quinolone-resistance determining regions of gyrA and parC were sequenced in nalidixic acid resistant strains and horizontally-transmitted quinolone-resistance genes were sought by PCR. Antimicrobial prescription practices were compared with antimicrobial resistance rates over a period spanning three decades.

Results

Before 2005, quinolone resistance was limited to low-level nalixidic acid resistance in fewer than 4% of E. coli isolates. In 2005, the proportion of isolates demonstrating low-level quinolone resistance due to elevated efflux increased and high-level quinolone resistance and resistance to the fluoroquinolones appeared. Fluoroquinolone resistance was attributable to single nucleotide polymorphisms in quinolone target genes gyrA and/or parC. By 2009, 35 (34.5%) of isolates were quinolone non-susceptible with nine carrying gyrA and parC SNPs and six bearing identical qnrS1 alleles. The antimalarial chloroquine was heavily used throughout the entire period but E. coli with quinolone-specific resistance mechanisms were only detected in the final half decade, immediately following the introduction of the fluoroquinolone antibacterial ciprofloxacin.

Conclusions

Fluoroquinolones, and not chloroquine, appear to be the selective force for fluoroquinolone-resistant fecal E. coli in this setting. Rapid evolution to resistance following fluoroquinolone introduction points the need to implement resistant containment strategies when new antibacterials are introduced into resource-poor settings with high infectious disease burdens.

Risk of functional gastrointestinal disorders in U.S. military following self-reported diarrhea and vomiting during deployment

INTRODUCTION

Military personnel are frequently deployed to regions of the world with high travelers' diarrhea (TD) rates. Pathogens associated with TD have been linked to several post-infectious sequelae, including functional gastrointestinal disorders (FGD), such as irritable bowel syndrome (IBS) and functional dyspepsia. Furthermore, stress associated with deployment may potentiate the increased FGD risk.

AIM

We sought to assess whether self-reported diarrhea, vomiting, and stressors during deployment were associated with increased FGD risk.

METHODS

Using active duty military medical encounter data from the Defense Medical Surveillance System (DMSS), we conducted a matched case-control study to assess the odds of FGD (IBS, functional constipation, functional diarrhea, dyspepsia) following self-reported diarrhea or vomiting during deployment. Only first-time deployers with detailed self-reporting of deployment-related exposures from 2008 and 2009 were included. Univariate and multivariate analyses were performed.

RESULTS

A total of 129 cases of FGD were identified, with the following distribution: constipation (n = 67), dyspepsia (n = 15), IBS (n = 22), and overlapping disorders (n = 25). Diarrhea and/or vomiting during deployment were significantly associated with the development of FGD. Other demographic factors were also associated with variable risk. We found no consistent effect of war-related stressors or non-combat-related correlates of stress.

CONCLUSIONS

Deployment-related TD is common in deployed military personnel and is associated with an increased risk of several FGD. When considering effective countermeasures and mitigation strategies, both the acute effects and chronic sequelae of enteric infections should be considered. Increased emphasis on existing and novel primary prevention strategies are needed, as well as outcome studies among those developing these conditions.

Effects of octreotide on jejunal hypersensitivity triggered by Cryptosporidium parvum intestinal infection in an immunocompetent suckling rat model

BACKGROUND

Similar to other bacterial or protozoan infections, human cryptosporidiosis may trigger postinfectious irritable bowel syndrome (IBS)-like symptoms, a condition in which enhanced visceral perception of pain during intestinal distension plays a pivotal role. In an immunocompetent suckling rat model which mimicks features of postinfectious IBS, Cryptosporidium parvum infection induces long-lasting jejunal hypersensitivity to distension in association with intestinal activated mast cell accumulation. The aim of the present study was to explore in this model whether octreotide, a somatostatin agonist analog, could prevent the development of jejunal hypersensitivity and intestinal mast cell/nerve fiber accumulation.

METHODS

Five-day-old Sprague-Dawley rats were infected with C. parvum and treated 10 days later with octreotide (50 g kg(-1) day(-1), i.p.) for 7 days.

KEY RESULTS

Compared with untreated infected rats, octreotide treatment of infected rats resulted in increased weight gain [day 23 postinfection (PI)], decreased food intake (day 16 PI), and a reduction in jejunal villus alterations (day 14 PI), CD3(+) IEL (day 37 PI) and mast cell (days 37 and 50 PI) accumulations, nerve fiber densities (day 50 PI), and hypersensitivity to distension (day 120 PI). In uninfected rats, the effects of octreotide treatment were limited to higher weight gain (days 16 and 23 PI) and decreased food intake (day 23 PI) compared with uninfected-untreated rats.

CONCLUSIONS & INFERENCES

Data confirms the relevance of the present rat model to postinfectious IBS studies and prompt further investigation of somatostatin-dependent regulatory interactions in cryptosporidiosis.

Survey of physician diagnostic and treatment practices for patients with acute diarrhea in Guangdong province, China

Although international clinical guidelines generally recommend performing bacterial stool culture in patients with acute diarrhea and fever and discourage routine antibiotic prescribing, clinical practice varies. Understanding practice patterns can help health officials assess the sensitivity of laboratory-based enteric infection surveillance systems and the need to improve antibiotic prescribing practices. We surveyed physicians in Guangdong province, China, to measure their practices for patients with acute diarrhea. A standardized questionnaire was used to interview physicians working in hospitals participating in a Salmonella surveillance system in Guangdong, China. The questionnaire asked physicians about their routine practice for patients with diarrhea, including how they managed the last patient they had seen with acute diarrhea. We calculated the odds ratio and 95% confidence interval for factors associated with ordering a stool culture and for prescribing antibiotics. We received surveys from 237 physicians across 22 hospitals in Guangdong. For the last patient with diarrhea whom they had evaluated, 134 (57%) reported ordering a stool culture. The most common reasons for not ordering a stool culture included that it takes too long to receive the result, that the patient is not willing to pay for the test, and that the patient's illness was too mild to warrant testing. Most physicians prescribed at least one medication for the last patient with diarrhea whom they had evaluated. Of the 237 physicians surveyed, 153 (65%) prescribed antibiotics, 135 (57%) probiotics, and 115 (49%), a gastric mucosal protective drug. In conclusion, physicians in Guangdong, China, reported high rates of ordering bacterial stool cultures from patients with diarrhea, possibly associated with their hospital's participation in a special surveillance project. The high rate of antibiotic prescribing suggests that efforts to promote judicious antibiotic use, such as physician education, are needed.

Empiric antimicrobial therapy and infectious diarrhea. Do we need local guidelines?

BACKGROUND

In the management of acute diarrhea, administration of antibiotics may be indicated. Appropriate antimicrobial therapy can shorten illness, reduce morbidity and can be life-saving in invasive infections. Emergence of microbial strains resistant to commonly used antibiotics means that treatment failures may become common. Because of changing patterns of resistance, knowledge of recent local patterns of susceptibility can guide the initial choice of antibiotics.

METHODS

A retrospective study was conducted to investigate the epidemiology of infective gastroenteritis in patients over 14years old in the region of Chania (Crete). We reviewed all positive stool cultures and susceptibilities of the pathogens recovered from patients with symptoms of acute diarrhea, from 2003 until October 2010.

RESULTS

Out of 194 positive stool cultures, we observed 139 cases of Salmonella enterica and 48 cases of Campylobacter jejuni. During the last 3years of observation there was an increased incidence of C. jejuni, especially after the tap water outbreak that occurred in our region in 2009.

DISCUSSION

In the vast majority of acute diarrhea in adults, antibiotics are of no benefit and overprescription may confer to side effects, costs and emergence of resistance. Antibiotics are initiated in cases of febrile diarrheas especially those believed to have moderate to severe disease. Considering the increased incidence of C. jejuni and the resistance of the great majority of isolated strains to quinolones as well as the sensitivity of Salmonella spp. to azithromycin, administration of azithromycin empirically for acute diarrhea, when indicated, could be appropriate in our region.

Real-time multiplex PCR for simultaneous detection of Campylobacter jejuni, Salmonella, Shigella and Yersinia species in fecal samples

Diarrheal diseases due to notifiable bacterial infections require rapid diagnosis of the causative pathogens. To facilitate detection, a real-time multiplex PCR was developed that identifies common diarrhea-causing bacteria in fecal samples. On the basis of published sequence data, sets of primers and probes were designed that were specific for Campylobacter jejuni, Salmonella, Shigella/enteroinvasive Escherichia coli EIEC, and Yersinia species, suitable for use in a one-tube PCR assay. The assay was assessed using a list of 137 well-defined intestinal bacterial strains or isolates. Furthermore, 393 routine clinical stool samples were analyzed, and the results of real-time multiplex PCR were compared with those obtained by established microbiological methods. The PCR yielded results within 3h including DNA purification. No false-positive signals or cross-reactions were observed. The analytical sensitivity was 10(3)cfumL(-1) for Campylobacter jejuni, 10(4)cfumL(-1) for Salmonella, and 10(5)cfumL(-1) for Shigella/EIEC and Yersinia, respectively. Compared with culture, PCR detected 79 out of 81 Campylobacter jejuni (97.5%), 71 out of 74 Salmonella (96%), 8 out of 8 Shigella (100%), and 10 out of 10 Yersinia-positive (100%) clinical samples. In culture-negative samples (n=192), PCR additionally detected 2 Shigella, 1 Salmonella, and 5 Campylobacter jejuni infections. Thus, the new real-time multiplex PCR provides reliable results within a short time and might be useful as an additional diagnostic tool whenever time is important in the diagnosis of enteropathogenic bacteria.

Food poisoning and diarrhea: small intestine effects

Transmission of foodborne pathogens remains a growing concern despite increasing public awareness and heightened federal measures to control infection. Over 76 million cases of acute diarrhea secondary to ingestion of contaminated food occur annually in the United States. Fortunately, most are self-limited and resolve without therapy, but up to 6000 deaths occur on an annual basis. Mechanisms of infection include consumption of a preformed toxin, formation of toxin following ingestion, and direct invasion of intestinal epithelial cells by the infecting organism. Diagnosis is most often confirmed through an accurate history, as cultures are often of low yield.

Efficacy of diosmectite (smecta) in the treatment of acute watery diarrhoea in adults: a multicentre, randomized, double-blind, placebo-controlled, parallel group study

Background. Although diosmectite has demonstrated efficacy in the treatment of acute watery diarrhoea in children, its efficacy in adults still needs to be assessed. The objective of this study was therefore to assess the efficacy of diosmectite on the time to recovery in adults with acute diarrhoea. Methods. A total of 346 adults with at least three watery stools per day over a period of less than 48 hours were prospectively randomized to diosmectite (6 g tid) or placebo during four days. The primary endpoint was time to diarrhoea recovery. Results. In the intention-to-treat population, median time to recovery was 53.8 hours (range [3.7–167.3]) with diosmectite (n = 166) versus 69.0 hours [2.2–165.2] with placebo, (n = 163; P = .029), which corresponds to a difference of 15.2 hours. Diosmectite was well tolerated. Conclusion. Diosmectite at 6 g tid was well tolerated and reduced the time to recovery of acute watery diarrhoea episode in a clinically relevant manner.

Inflammatory bowel disease

This review focuses on the prominent etiological and pathogenetic aspects of inflammatory bowel disease (IBD), with particular attention being paid to the mucosal immune response to commensal micro-organisms in health and disease. Pathogenetic implications for target therapy will also be discussed. The clinical presentation, diagnostic aspects, and currently recommended therapeutic options for the two main types of IBD are also taken into consideration, including manifestations of these conditions in the oral cavity.

Vomiting, diarrhea, constipation, and gastroenteritis

Diseases that cause vomiting, diarrhea, constipation, and gastroenteritis are major problems for populations worldwide. Patients, particularly infants, elderly, and immunocompromised individuals, may present at any point in a wide spectrum of disease states, underscoring the need for the clinician to treat these ailments aggressively. Several promising new treatment modalities, from oral rehydration solutions to antiemetic therapies, have been introduced over the past decade. Future directions include the use of probiotic agents and better tolerated rehydration solutions. Gastrointestinal disease will continue to be a focus worldwide in the search for better ways to cure illnesses associated with vomiting and diarrhea.

Systematic review of animal models of post-infectious/post-inflammatory irritable bowel syndrome

AIMS

Post-infectious irritable bowel syndrome (PI-IBS) is a subset of IBS which occurs after an episode of acute gastrointestinal infections. The mechanisms of PI-IBS are not fully understood. Currently, numerous animal models have been used in the study of PI-IBS. This article reviews the strengths and weaknesses of these models.

METHODS

All relevant articles were identified by searching in Ovid SP from 1962, the year the term PI-IBS was coined, up to December 31, 2009. The types of model were categorized as either post-infectious or post-inflammatory, and the characteristics of each kind of model were listed.

RESULTS

Based on our literature search, 268 articles were identified. Of those articles, 50 were included in this review. The existing PI-IBS models include infection with bacteria (e.g., Campylobacter jejuni, Salmonella enterica, and Campylobacter rodentium), and infection with parasites (e.g., Trichinella spiralis, Nippostrongylus brasiliensis, and Cryptosporidium parvum). The post-inflammatory IBS models are commonly induced with chemical agents, such as acetic acid, deoxycholic acid, dextran sulfate sodium, mustard oil, zymosan, and trinitrobenzene sulfonic acid (TNBS). TNBS is the most commonly used agent for post-inflammatory IBS models, but the experimental protocol varies. These models have one or more aspects similar to IBS patients.

CONCLUSIONS

Different methods have been used for the development of post-infectious or post-inflammatory IBS models. Each model has its weaknesses and strengths. More studies are needed to establish post-infection IBS models using more common pathogens. A standard protocol in developing TNBS-induced post-inflammatory IBS model is needed.

Physician use of parasite tests in the United States from 1997 to 2006 and in a Utah Cryptosporidium outbreak in 2007

Parasitic infection is uncommon in the United States, but surveys suggest that physicians test when the presence of parasites is unlikely and fail to order appropriate testing when suspicion is high. Numerous studies confirm that immunoassays are more sensitive for Giardia and Cryptosporidium detection, but our experience was that physicians preferentially used ovum and parasite examination (O&P). We conducted a retrospective study of fecal parasite testing at a referral laboratory nationally (1997 to 2006) and during a Cryptosporidium outbreak (Utah, 2007) to correlate physician use of O&P and enzyme immunoassays (EIAs) with the yield of parasites detected. Nationally, of 170,671 episodes, 76.0% (n = 129,732) included O&P, 27.9% (n = 47,666) included Giardia EIA, and 5.7% (n = 9,754) included Cryptosporidium EIA. Most pathogens were Giardia or Cryptosporidium. More episodes were positive when EIA was performed (n = 1,860/54,483 [3.4%]) than when O&P only was performed (n = 1,667/116,188 [1.4%]; P < 0.001), and EIA was more sensitive than O&P. However, more O&P results were positive among patients with both O&P and EIA performed (2.5%) than among those with O&P only performed (1.4%; P < 0.001), suggesting that patients tested by O&P only may have been at lower risk. During the first 10 weeks of the outbreak, physicians also preferentially used O&P over EIA, but no Cryptosporidium cases were detected by O&P. We conclude that clinicians frequently use O&P testing when test performance and epidemiology support the use of immunoassays or no testing. We recommend that stool O&P be limited to patients with negative immunoassay results and persistent symptoms or individuals at increased risk for non-Giardia, non-Cryptosporidium infection. An evidence-based algorithm for the evaluation of patients with suspected intestinal parasitic infection is proposed.

Mass spectrometry biotyper system identifies enteric bacterial pathogens directly from colonies grown on selective stool culture media

We evaluated the performance and cost-effectiveness of a matrix-assisted laser desorption ionization time-of-flight mass spectrometry-based Biotyper system for the routine identification of common enteric bacterial pathogens seen in middle Tennessee from suspicious colonies grown on selective stool culture media. A total of 304 suspicious colonies were selected and further identified from 605 stool specimens. The suspicious colonies were analyzed by the Biotyper system, and the results were compared to those from routine phenotypic methods, which identified 22 Salmonella species, 39 Shigella species, 3 enterohemorrhagic Escherichia coli (EHEC) isolates, 2 Yersinia enterocolitica isolates, 2 Campylobacter species, and 236 gastrointestinal normal flora isolates. The Biotyper system correctly identified the Salmonella species, Yersinia enterocolitica, and Campylobacter species but failed to distinguish the Shigella species and EHEC isolates from E. coli. Among the 236 normal flora isolates, 233 (98.7%) and 228 (96.6%) agreed at the genus and species levels, respectively, between the phenotypic and Biotyper methods. Organism identification scores were insignificantly different between colonies directly from selective media and subsequently from pure subculture. The entire Biotyper identification procedure, from smear preparation to final result reporting, can be completed within 30 min. The Biotyper system provides a rapid and simple screening tool for identifying many, but not all, suspicious colonies grown on selective media within 24 h after inoculation, which shortens test turnaround time by 2 to 3 days.

Three-hour molecular detection of Campylobacter, Salmonella, Yersinia, and Shigella species in feces with accuracy as high as that of culture

Campylobacter jejuni and Salmonella, Shigella, and Yersinia species (along with Shiga toxin-producing Escherichia coli) are the most common causes of acute bacterial diarrheal disease in the United States. Current detection techniques are time-consuming, limiting usefulness for patient care. We developed and validated a panel of rapid PCR assays for the detection and identification of C. jejuni, C. coli, Salmonella, and Yersinia species and Shigella and enteroinvasive E. coli in stool samples. A total of 392 archived stool specimens, previously cultured for enteric pathogens, were evaluated by PCR. Overall, 104 stool specimens had been culture positive (C. jejuni/coli [n = 51], Salmonella species [n = 42], Shigella species [n = 6], and Yersinia species [n = 5]). Compared to culture, the overall sensitivity and specificity of PCR detection of these organisms were 92 and 98% (96/104 and 283/288), respectively, from fresh or Cary Blair stool (P = 0.41); 87 and 98% (41/47 and 242/246), respectively, from fresh stool (P = 0.53); and 96 and 98% (55/57 and 41/42), respectively, from Cary Blair stool (P = 0.56). For individual genera, PCR was as sensitive as the culture method, with the exception of Salmonella culture using selenite enrichment for which PCR was less sensitive than culture from fresh, but not Cary Blair (P = 0.03 and 1.00, respectively) stools. This PCR assay panel for the rapid diagnosis of acute infectious bacterial diarrheal pathogens has a sensitivity and specificity equivalent to that of culture for stools in Cary Blair transport medium. Paired with reflexive culture of stools testing positive, this should provide an improvement in care for patients with acute infectious diarrheal disease.

Norovirus gastroenteritis

Recent epidemiologic studies have shown that norovirus is one of the most frequent causes of acute nonbacterial gastroenteritis. Reverse-transcription polymerase chain reaction and nucleotide sequencing are the means by which the hundreds of norovirus strains have been identified, named, and classified into genogroups and genetic clusters. They are also the means by which a particular strain is traced from the source of an outbreak throughout its spread. These molecular techniques have been combined with classic epidemiology to investigate norovirus outbreaks in diverse settings, including hospitals, nursing homes, dining locations, schools, daycare centers, and vacation venues. Outbreaks are difficult to control because of the apparent ease of transmission through food, water, person-to-person contact, and environmental surfaces. Almost all patients with norovirus gastroenteritis recover completely, but hospital and nursing home outbreaks have been associated with morbidity and mortality. The diagnostic and management approach to an individual patient is to use clinical and epidemiologic findings to rule out "not norovirus." At the first sign that there is an outbreak, strict compliance with cleaning, disinfection, and work release guidelines is important to prevent further spread.

Best practice in primary care pathology: review 12

This twelfth best practice review examines four series of common primary care questions in laboratory medicine: (i) antiepileptic drug monitoring; (ii) infectious diarrhoea; (iii) methicillin resistant Staphylococcus aureus; and (iv) brain natriuretic peptide. The review is presented in question–answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by MEDLINE EMBASE searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus rather than evidence-based. They will be updated periodically to take account of new information.

The genus Aeromonas: taxonomy, pathogenicity, and infection

Over the past decade, the genus Aeromonas has undergone a number of significant changes of practical importance to clinical microbiologists and scientists alike. In parallel with the molecular revolution in microbiology, several new species have been identified on a phylogenetic basis, and the genome of the type species, A. hydrophila ATCC 7966, has been sequenced. In addition to established disease associations, Aeromonas has been shown to be a significant cause of infections associated with natural disasters (hurricanes, tsunamis, and earthquakes) and has been linked to emerging or new illnesses, including near-drowning events, prostatitis, and hemolytic-uremic syndrome. Despite these achievements, issues still remain regarding the role that Aeromonas plays in bacterial gastroenteritis, the extent to which species identification should be attempted in the clinical laboratory, and laboratory reporting of test results from contaminated body sites containing aeromonads. This article provides an extensive review of these topics, in addition to others, such as taxonomic issues, microbial pathogenicity, and antimicrobial resistance markers.