The role of antibiotics in the treatment of infectious diarrhea

Anti-diarrheal effect of piperine possibly through the interaction with inflammation inducing enzymes: In vivo and in silico studies

Piperine is a natural alkaloid that possesses a variety of therapeutic properties, including anti-inflammatory, antioxidant, antibacterial, and anticarcinogenic activities. The present study aims to assess the medicinal benefits of piperine as an anti-diarrheal agent in a chick model by utilizing in vivo and in silico techniques. For this, castor oil was administered orally to 2-day-old chicks to cause diarrhea. Bismuth subsalicylate (10 mg/kg), loperamide (3 mg/kg), and nifedipine (2.5 mg/kg) were used as positive controls, while the vehicle was utilized as a negative control. Two different doses (25 and 50 mg/kg b.w.) of the test sample (piperine) were administered orally, and the highest dose was tested with standards to investigate the synergistic activity of the test sample. In our findings, piperine prolonged the latent period while reducing the number of diarrheal feces in the experimental chicks during the monitoring period (4 h). At higher doses, piperine appears to reduce diarrheal secretion while increasing latency in chicks. Throughout the combined pharmacotherapy, piperine outperformed bismuth subsalicylate and nifedipine in terms of anti-diarrheal effects with loperamide. In molecular docking, piperine exhibited higher binding affinities towards different inflammatory enzymes such as cyclooxygenase 1 (-7.9 kcal/mol), cyclooxygenase 2 (-8.4 kcal/mol), nitric oxide synthases (-8.9 kcal/mol), and L-type calcium channel (-8.8 kcal/mol), indicating better interaction of PP with these proteins. In conclusion, piperine showed a potent anti-diarrheal effect in castor oil-induced diarrheal chicks by suppressing the inflammation and calcium ion influx induced by castor oil.

Adherence of Doctors to Standard Diarrhoeal Management Guideline During Treatment of Under-Five Diarrhoeal Episodes: A Study From Eastern India

Introduction

Diarrhoea is one of the major preventable causes of childhood death in tribal areas of India. Most acute diarrhoea in childhood can be managed with oral rehydration salt (ORS) and zinc. This study aimed to assess the adherence of doctors to standard diarrheal management guidelines while treating under-five diarrhoeal episodes.

Methods

The cross-sectional study was conducted in 10 blocks of Kandhamal district in southern Odisha, India. The under-five childhood diarrhoea prescriptions from July to August 2018 were audited during September 2018. One health facility from each block and 15 prescriptions from each health facility were selected randomly. Data were collected and entered in Epicollect5 and analyzed using Statistical Packages for Social Sciences Version 22.0 (IBM Corp., Armonk, NY). Categorical variables were presented as proportions.

Results

A total of 150 under-five acute diarrhoea prescriptions were audited from 10 health facilities. One hundred ten prescriptions were from the out-patient department and 40 prescriptions were from the admitted diarrhoeal patients. The majority of them included ORS (77.3%) and zinc (75.3%) in the prescription, however, only half of the prescriptions (52.7%) had recommended dose and duration of zinc. All admitted patients received intravenous fluids. Most prescriptions (89.3%) did not document the hydration status of the patient. All prescriptions were silent about the severe acute malnutrition status of the children before administering fluid therapy. Antibiotics were prescribed in 80% of the prescriptions. Prebiotics, probiotics and anti-spasmodic were prescribed in 37.3% of the prescriptions.

Conclusion

Adherence of doctors to acute diarrheal management guidelines for the management of under-five diarrhoea was poor in our study. Further researches and training are required to improve childhood diarrhoea management in health facilities of tribal areas of India.

Microgels Sopping Up Toxins-GM1a-Functionalized Microgels as Scavengers for Cholera Toxin

Vibrio cholerae is a Gram-negative bacterium that causes secretory diarrhea and constitutes a major health threat in the industrialized world and even more in developing countries. Its main virulence factor is the cholera toxin, which is internalized by intestinal epithelial cells after binding to the glycosphingolipid receptor GM1a on their apical surface. A potential future solution to dampen complications of cholera infection is by scavenging the cholera toxin by presenting competitive binding motifs to diminish the in vivo toxicity of V. cholerae. Here, we generate GM1a-functionalized and biocompatible microgels with diameters of 20 μm using drop-based microfluidics. The microgels are designed to exhibit a mesoporous and widely meshed network structure, allowing diffusion of the toxin protein deep into the microgel scavengers. Flow cytometry demonstrates strong and multivalent binding at high capacity of these microgels to the binding domain of the cholera toxin. Cell culture-based assays reveal the ability of these microgels to scavenge and retain the cholera toxin in direct binding competition to colorectal cells. This ability is evidenced by suppressed cyclic adenosine monophosphate production as well as reduced vacuole formation in mucus-forming colorectal HT-29 cells. Therefore, glycan-functionalized microgels show great potential as a non-antibiotic treatment for toxin-mediated infectious disorders.

Explicit definitions of potentially inappropriate prescriptions of antibiotics in older patients: a compilation derived from a systematic review

Potentially inappropriate prescriptions (PIPs) of antibiotics (antibiotic-PIPs) are generally detected by applying implicit definitions based on expert opinion. Explicit definitions are less frequently used, even though this approach would enable the automated detection of antibiotic-PIPs in electronic health records. Here, explicit definitions of antibiotic-PIPs used in studies of older adults were systematically reviewed. The MEDLINE^®, Scopus^® and Web of Science^TM core collection databases were searched with a combination of three terms and their synonyms: 'potentially inappropriate prescription' AND 'antibiotic treatment' AND 'older patients'. Following standardised selection of publications, explicit definitions of antibiotic-PIPs were extracted and were classified into infectious diseases domains and subdomains. A total of 600 search queries identified 4270 records, 93 of which were selected for review. A total of 160 mentions of antibiotic-PIPs were found, corresponding to 62 distinct definitions in 19 infectious diseases domains. Nearly one-half of the definitions were related to upper respiratory tract infections (n = 11 definitions; 17.7%), lower respiratory tract infections (n = 8; 12.9%) and drug-drug interactions (n = 11; 17.7%). Almost 75% of definitions (n = 46) were mentioned in a single study only. Only three definitions concerned critically important antibiotics such as third-generation cephalosporins and fluoroquinolones. This systematic review identified 62 explicit definitions of antibiotic-PIPs. Most of the definitions were not found in more than one study and they varied in the degree of precision. We advocate the implementation of an expert consensus on explicit definitions of antibiotic-PIPs that correspond to today's challenges in public health.

A single nucleotide change in mutY increases the emergence of antibiotic-resistant Campylobacter jejuni mutants

OBJECTIVES

Mutator strains play an important role in the emergence of antibiotic-resistant bacteria. Campylobacter jejuni is a leading cause of foodborne illnesses worldwide and is increasingly resistant to clinically important antibiotics. The objective of this study was to identify the genetic basis that contributes to a mutator phenotype in Campylobacter and determine the role of this phenotype in the development of antibiotic resistance.

METHODS

A C. jejuni isolate (named CMT) showing a mutator phenotype was subjected to WGS analysis. Comparative genomics, site-specific reversion and mutation, and gene knockout were conducted to prove the mutator effect was caused by a single nucleotide change in the mutY gene of C. jejuni.

RESULTS

The C. jejuni CMT isolate showed ∼ 100-fold higher mutation frequency to ciprofloxacin than the WT strain. Under selection by ciprofloxacin, fluoroquinolone-resistant mutants emerged readily from the CMT isolate. WGS identified a single nucleotide change (G595 → T) in the mutY gene of the CMT isolate. Further experiments using defined mutant constructs proved its specific role in elevating mutation frequencies. The mutY point mutation also led to an ∼ 700-fold increase in the emergence of ampicillin-resistant mutants, indicating its broader impact on antibiotic resistance. Structural modelling suggested the G595 → T mutation probably affects the catalytic domain of MutY and consequently abolishes the anti-mutator function of this DNA repair protein.

CONCLUSIONS

The G595 → T mutation in mutY abolishes its anti-mutator function and confers a mutator phenotype in Campylobacter, promoting the emergence of antibiotic-resistant Campylobacter.

Rectal bleeding in Egyptian children

AIM

In a prospective study to outline the aetiology of bleeding per rectum (BPR) in Egyptian infants and children, a subsidiary aim was to define some of the clinical characteristics of the different aetiologies.

SUBJECTS AND METHODS

194 children with BPR are described. The diagnostic work-up included laboratory investigations, radiological and endoscopic assessment, radio-isotope scanning, angiography and histopathological examination of mucosal biopsies, as appropriate.

RESULTS

Ages ranged from 3 to 192 months with a mean (SD) of 49.8 (43.5). Infectious enterocolitis was the most common cause (37.1%). Others included colorectal polyps (21.1%), chronic colitis (16%) including inflammatory bowel diseases (5.2%), allergic colitis (2.6%), solitary rectal ulcer syndrome (1.5%) and non-specific colitis (6.7%). Intussusception and Meckel's diverticulae were the cause in 7.3% and 2.6%, respectively, while other aetiologies included vascular (6.2%), systemic (3.6%), local anal (3.1%) and upper gastro-intestinal causes (1.5%). In 1.5% of cases, the cause remained 'obscure'.

CONCLUSION

In Egyptian children, infectious enterocolitis followed by colorectal polyps and chronic colitis are major causes of BPR.

Options for treating resistant Shigella species infections in children

Infection due to Shigella species remains an important public health problem, especially in developing countries where it remains the most common cause of bloody diarrhea. In the United States (US), 10,000 to 15,000 cases of shigellosis are reported each year in both children and adults. US surveillance data from 2004 has demonstrated increased resistance in Shigella species to first-line antibiotics such as ampicillin and trimethoprim-sulfamethoxazole, with approximately 37% of isolates demonstrating resistance to both ampicillin and trimethoprim-sulfamethoxazole. Since approximately 69% of Shigella infections occur in children younger than 5 years of age, it is important that alternative antibiotics other than typical first-line agents such as ampicillin and trimethoprim-sulfamethoxazole be available to treat Shigella infections in this population. The American Academy of Pediatrics (AAP) recommends cefixime, ceftriaxone, azithromycin, and fluoroquinolones as alternative antibiotics for the treatment of Shigella species infections in children. This paper will review the microbiology, susceptibility, efficacy and safety data of these alternative antibiotics with regard to the treatment of Shigella species infections in children, and will attempt to define the role of each of these agents in the pediatric population.

When does overuse of antibiotics become a tragedy of the commons?

BACKGROUND

Over-prescribing of antibiotics is considered to result in increased morbidity and mortality from drug-resistant organisms. A resulting common wisdom is that it would be better for society if physicians would restrain their prescription of antibiotics. In this view, self-interest and societal interest are at odds, making antibiotic use a classic "tragedy of the commons".

METHODS AND FINDINGS

We developed two mathematical models of transmission of antibiotic resistance, featuring de novo development of resistance and transmission of resistant organisms. We analyzed the decision to prescribe antibiotics as a mathematical game, by analyzing individual incentives and community outcomes.

CONCLUSIONS

A conflict of interest may indeed result, though not in all cases. Increased use of antibiotics by individuals benefits society under certain circumstances, despite the amplification of drug-resistant strains or organisms. In situations where increased use of antibiotics leads to less favorable outcomes for society, antibiotics may be harmful for the individual as well. For other scenarios, where a conflict between self-interest and society exists, restricting antibody use would benefit society. Thus, a case-by-case assessment of appropriate use of antibiotics may be warranted.

A fluoroquinolone resistance associated mutation in gyrA Affects DNA supercoiling in Campylobacter jejuni

The prevalence of fluoroquinolone (FQ)-resistant Campylobacter has become a concern for public health. To facilitate the control of FQ-resistant (FQ^R) Campylobacter, it is necessary to understand the impact of FQ^R on the fitness of Campylobacter in its natural hosts as understanding fitness will help to determine and predict the persistence of FQ^RCampylobacter. Previously it was shown that acquisition of resistance to FQ antimicrobials enhanced the in vivo fitness of FQ^RCampylobacter. In this study, we confirmed the role of the Thr-86-Ile mutation in GyrA in modulating Campylobacter fitness by reverting the mutation to the wild-type (WT) allele, which resulted in the loss of the fitness advantage. Additionally, we determined if the resistance-conferring GyrA mutations alter the enzymatic function of the DNA gyrase. Recombinant WT gyrase and mutant gyrases with three different types of mutations (Thr-86-Ile, Thr-86-Lys, and Asp-90-Asn), which are associated with FQ^R in Campylobacter, were generated in E. coli and compared for their supercoiling activities using an in vitro assay. The mutant gyrase with the Thr-86-Ile change showed a greatly reduced supercoiling activity compared with the WT gyrase, while other mutant gyrases did not show an altered supercoiling. Furthermore, we measured DNA supercoiling within Campylobacter cells using a reporter plasmid. Consistent with the results from the in vitro supercoiling assay, the FQ^R mutant carrying the Thr-86-Ile change in GyrA showed much less DNA supercoiling than the WT strain and the mutant strains carrying other mutations. Together, these results indicate that the Thr-86-Ile mutation, which is predominant in clinical FQ^RCampylobacter, modulates DNA supercoiling homeostasis in FQ^RCampylobacter.

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.

Practice and attitudes regarding the management of childhood diarrhoea among pharmacies in Thailand

OBJECTIVES

to compare practice behaviour and attitudes of pharmacy personnel in the management of childhood diarrhoea between type I (requiring a pharmacist to be on duty) and type II (pharmacist not required) pharmacies, between those surveyed in 2008 and in 2001, and between new-generation (graduation ≤ 10 years) and old-generation (graduation >10 years) pharmacists.

METHODS

the setting was 115 pharmacies in a city in the south of Thailand. The study was separated into two phases: a simulated client method to evaluate history taking, drug dispensing and advice giving among pharmacy personnel and a questionnaire to measure attitudes and factors affecting diarrhoea treatment.

KEY FINDINGS

in the simulated client method study, questions asked and advice given by the providers (the pharmacists or non-pharmacists responding to the simulated clients), especially in type II pharmacies, were insufficient. Only 5.2% of pharmacies correctly dispensed for a child with viral diarrhoea, using oral rehydration salts (ORS) alone. Appropriate ORS dispensing of providers was not affected by shop type, survey time or peer generation. However, 52.2% of providers inappropriately dispensed antibiotics for such illness. In the questionnaire study, 108 completed surveys were obtained (a response rate of 93.9%). The providers working in 2008 more strongly agreed that ORS was effective, safe, used by health professionals and requested by patients, relative to those in 2001 (P < 0.05). No potential factor influencing the actual ORS dispensing was identified. Nevertheless, antibiotic dispensing was affected by beliefs in producing recovery and high profit.

CONCLUSIONS

practice and attitudes of pharmacy personnel were inappropriate in the management of childhood diarrhoea. Revision of the pharmacy curriculum did not result in improvement of practice as seen by the similarity of practice patterns among the 2001 and 2008 samples. Improvement of knowledge and practice behaviour among providers in pharmacies is needed.

Bacterial colitis

Bacterial colitis results in an inflammatory-type diarrhea that is characterized by bloody, purulent, and mucoid stool. These diseases have been designated as bacterial hemorrhagic enterocolitis. Associated symptoms include fever, tenesmus, and severe abdominal pain. The pathologic changes range from superficial exudative enterocolitis to a transmural enterocolitis with ulceration. Common pathologic bacteria causing bacterial colitis include Campylobacter, Salmonella, Shigella, Escherichia, and Yersinia species. The primary source of transmission is fecal-oral spread and ingestion of contaminated food and water. Although detailed history and identification of specific risk factors assist in the diagnosis, definitive diagnosis requires bacterial identification. Therefore, the physician must be familiar with the disease pathophysiology, epidemiology, and specific diagnostic modalities for clinical diagnosis and management. Specific tests are used to detect enteric pathogens and include stool and rectal swab culture, histology, and identification of specific bacterial toxins. Although many of these bacterial colitis infections are self-limiting, antibiotics should be used for high-risk patients and patients with complicated disease.

Ciprofloxacin decreases survival in HT-29 cells via the induction of TGF-beta1 secretion and enhances the anti-proliferative effect of 5-fluorouracil

BACKGROUND AND PURPOSE

Fluoroquinolones are potent anti-microbial agents with multiple effects on host cells and tissues. Previous studies have highlighted their pro-apoptotic effect on human cancer cells and an immunoregulatory role in animal models of inflammatory bowel disease. We examined the effect of ciprofloxacin on proliferation, cell cycle and apoptosis of HT-29 cells, a human colonic epithelial cell line sensitive to transforming growth factor (TGF)-beta1-mediated growth inhibition and its role in TGF-beta1 production. We also examined the effect of ciprofloxacin on proliferation of HT-29 cells in combination with 5-fluorouracil (5-FU), a well-established pro-apoptotic agent.

EXPERIMENTAL APPROACH

Using subconfluent cultures of HT-29 and Caco-2 cells, we studied the effect of ciprofloxacin, TGF-beta1 and 5-FU on proliferation, apoptosis, necrosis and cell cycle. The effect of ciprofloxacin on TGF-beta1 mRNA expression and production was studied in RNA extracts and cell culture supernatants respectively, using confluent cultures.

KEY RESULTS

Ciprofloxacin decreased proliferation of HT-29 cells in a concentration- and time-dependent manner. This was mediated by accumulation of HT-29 cells into the S-phase but without any effect on apoptosis or necrosis. Additionally, ciprofloxacin enhanced the antiproliferative effect of 5-FU. Interestingly, ciprofloxacin was found to up-regulate TGF-beta1 production by HT-29 cells and its anti-proliferative effect was abolished when TGF-beta1 was blocked. Confirming this mechanism further, ciprofloxacin had no effect on Caco-2, a human colonic epithelial cell line that lacks functional TGF-beta1 receptors.

CONCLUSIONS AND IMPLICATIONS

We demonstrate a novel anti-proliferative and immunoregulatory effect of ciprofloxacin on human intestinal epithelial cells mediated via TGF-beta1.

Key role of Mfd in the development of fluoroquinolone resistance in Campylobacter jejuni

Campylobacter jejuni is a major food-borne pathogen and a common causative agent of human enterocolitis. Fluoroquinolones are a key class of antibiotics prescribed for clinical treatment of enteric infections including campylobacteriosis, but fluoroquinolone-resistant Campylobacter readily emerges under the antibiotic selection pressure. To understand the mechanisms involved in the development of fluoroquinolone-resistant Campylobacter, we compared the gene expression profiles of C. jejuni in the presence and absence of ciprofloxacin using DNA microarray. Our analysis revealed that multiple genes showed significant changes in expression in the presence of a suprainhibitory concentration of ciprofloxacin. Most importantly, ciprofloxacin induced the expression of mfd, which encodes a transcription-repair coupling factor involved in strand-specific DNA repair. Mutation of the mfd gene resulted in an approximately 100-fold reduction in the rate of spontaneous mutation to ciprofloxacin resistance, while overexpression of mfd elevated the mutation frequency. In addition, loss of mfd in C. jejuni significantly reduced the development of fluoroquinolone-resistant Campylobacter in culture media or chickens treated with fluoroquinolones. These findings indicate that Mfd is important for the development of fluoroquinolone resistance in Campylobacter, reveal a previously unrecognized function of Mfd in promoting mutation frequencies, and identify a potential molecular target for reducing the emergence of fluoroquinolone-resistant Campylobacter.

Regional and seasonal differences in incidence and antibiotic resistance of Campylobacter from a nationwide surveillance study in The Netherlands: an overview of 2000-2004

Campylobacter is the most common cause of bacterial gastroenteritis worldwide. This study describes regional and seasonal differences among culture-proven Campylobacter infections in The Netherlands in 2000-2004. Data were used from two ongoing projects in The Netherlands, covering 3 million and 8 million inhabitants, respectively, for surveillance of infectious diseases. The incidence of Campylobacter infection was highest in the south of The Netherlands (55.7/100,000 vs. an average of 39.1/100,000 in other regions). The incidence in urbanised areas was 41.9/100,000 vs. 32.4/100,000 in rural areas. High stable rates of resistance to fluoroquinolones (35%) were observed. Resistance to erythromycin increased from 1.9% (in 2001) to 2.7% (in 2004). The highest rates of resistance to erythromycin were found in the south. Resistance rates increased with increasing urbanisation, most obviously for fluoroquinolones (35.9% urban vs. 27.10% rural). An inverse relationship was observed between the incidence of infection (high in summer, low in winter) and resistance to both fluoroquinolones and macrolides. Resistance to fluoroquinolones was higher in travel-related infections (54%) than in endemic infections (33%). Differences in regional incidence and resistance rates of Campylobacter infections were found. Foreign travel appeared to be associated with higher resistance rates. Given the high fluoroquinolone resistance rate, empirical treatment of severe, microbiologically confirmed, Campylobacter infection with a fluoroquinolone should be discouraged, pending susceptibility testing.

Immune response, ciprofloxacin activity, and gender differences after human experimental challenge by two strains of enterotoxigenic Escherichia coli

In order to test vaccines against enterotoxigenic Escherichia coli (ETEC)-induced diarrhea, challenge models are needed. In this study we compared clinical and immunological responses after North American volunteers were orally challenged by two ETEC strains. Groups of approximately eight volunteers received 10(9) or 10(10) CFU of E. coli B7A (LT+ ST+ CS6+) or 10(8) or 10(9) CFU of E. coli H10407 (LT+ ST+ CFA/I+). About 75% of the volunteers developed diarrhea after challenge with 10(10) CFU B7A or either dose of H10407. B7A had a shorter incubation period than H10407 (P = 0.001) and caused milder illness; the mean diarrheal output after H10407 challenge was nearly twice that after B7A challenge (P = 0.01). Females had more abdominal complaints, and males had a higher incidence of fever. Ciprofloxacin generally diminished or stopped symptoms and shedding by the second day of antibiotic treatment, but four subjects shed for one to four additional days. The immune responses to colonization factors CS6 and colonization factor antigen I (CFA/I) and to heat-labile toxin (LT) were measured. The responses to CFA/I were the most robust responses; all volunteers who received H10407 had serum immunoglobulin A (IgA) and IgG responses, and all but one volunteer had antibody-secreting cell (ASC) responses. One-half the volunteers who received B7A had an ASC response to CS6, and about one-third had serum IgA or IgG responses. Despite the differences in clinical illness and immune responses to colonization factors, the immune responses to LT were similar in all groups and were intermediate between the CFA/I and CS6 responses. These results provide standards for immune responses after ETEC vaccination.

Antimicrobial Use and Outcomes in Patients with Multidrug-Resistant and Pansusceptible Salmonella Newport Infections, 2002–2003

Multidrug-resistant Salmonella Newport with decreased susceptibility to ceftriaxone (MDR-AmpC) is becoming increasingly common in its food animal reservoirs and in humans. Few data exist on rates of antimicrobial use or differences in clinical outcomes in persons infected with MDR-AmpC or other Salmonella strains. We conducted a case-comparison analysis of data from a multistate population-based case-control study to identify antimicrobial treatment choices and differences in clinical outcomes in those infected with MDRAmpC compared to pansusceptible S. Newport. Of isolates from 215 laboratory-confirmed S. Newport cases, 54 (25%) were MDR-AmpC, 146 (68%) were pansusceptible, and 15 (7%) had other resistance patterns; 146 (68%) patients with S. Newport were treated with antimicrobial agents and 66 (33%) were hospitalized. Over two-thirds of cases at low-risk for serious complications received antimicrobial therapy, most commonly with fluoroquinolones, to which this strain was susceptible. There were no significant differences in symptoms, hospitalization, duration of illness, or other outcomes between the persons infected with MDR-AmpC and pansusceptible S. Newport. Although currently prevalent MDR-AmpC S. Newport strains remains susceptible to the antimicrobial most commonly prescribed for it, continued efforts to reduce unnecessary use of antimicrobial agents in food animals and humans are critical to prevent further development of resistance to quinolones and cephalosporins, which is likely to lead to substantial adverse outcomes.

Conduite à tenir devant une diarrhée aiguë. Étiologies

Les diarrhées aiguës constituent un problème de santé publique du fait de leur grande fréquence. Leur origine est presque toujours infectieuse et leur évolution spontanément résolutive, le plus souvent en moins de 3 jours. Seul 1 % des diarrhées nécessite d'emblée des explorations complémentaires, notamment des examens de selles, car leur présentation clinique évoque une colite aiguë sous-jacente (selles sanglantes, douleurs abdominales circonscrites), du fait d'un terrain fragile sous-jacent avec un risque immédiat pour le malade, ou d'un contexte particulier (séjour sous les tropiques…). Ces examens de selles doivent être orientés afin de guider le biologiste et améliorer la rentabilité des prélèvements, qui s'avère sinon très faible et coûteuse à l'échelle d'une population. Une antibiothérapie empirique basée essentiellement sur les fluoroquinolones est ensuite licite dans ces cas sélectionnés, en attendant les résultats des examens. Ces explorations sont aussi justifiées lorsque la diarrhée persiste au-delà de 3 jours. Enfin, lorsque l'épisode se prolonge au-delà de 5 jours, avec des prélèvements de selles négatifs, un avis spécialisé est nécessaire. Ainsi, seule une petite proportion de ces diarrhées aiguës va nécessiter une endoscopie, permettant de parler ainsi de colite ou de rectocolite. Au plan thérapeutique, la réhydratation précoce chez l'enfant reste d'actualité car elle a prouvé son efficacité en termes de mortalité depuis plus de deux décennies, principalement dans les pays en voie de développement.

Acute infectious gastroenteritis in adults. Seven steps to management and prevention

In caring for patients with acute gastroenteritis, the physician's primary task is to assess the severity of illness and to tailor fluid and electrolyte replacement and symptomatic therapy accordingly. Antibiotics are seldom indicated for acute gastroenteritis, and it is up to the physician to make a rational, informed choice about their use. Narrowing the considerations in differential diagnosis can help guide decision making about the need for diagnostic tests, specific therapy, and public health intervention.

Diarrhoea in children: an interface between developing and developed countries

Despite much progress in the understanding of pathogenesis and of management, diarrhoeal illnesses remain one of the most important causes of global childhood mortality and morbidity. Infections account for most illnesses, with pathogens employing ingenious mechanisms to establish disease. In the developed world, an upsurge in immune-mediated gut disorders might have resulted from a disruption of normal bacterial-epithelial cross-talk and impaired maturation of the gut's immune system. Oral rehydration therapies are the mainstay of management of gastroenteritis, and their composition continues to improve. Malnutrition remains the major adverse prognostic indicator for diarrhoea-related mortality, emphasising the importance of nutrition in early management. Drugs are of little use, except for specific indications although new agents that target mechanisms of secretory diarrhoea show promise, as do probiotics. However, preventive strategies on a global scale might ultimately hold the greatest potential to reduce the burden of diarrhoeal disease. These strategies include vaccines and, most importantly, policies to address persisting inequalities between the developed and developing worlds with respect to nutrition, sanitation, and access to safe drinking water.

Prevention of toxin-induced intestinal ion and fluid secretion by a small-molecule CFTR inhibitor

BACKGROUND & AIMS

The cystic fibrosis transmembrane conductance regulator (CFTR) provides an important apical route for Cl(-) secretion across intestinal epithelia. A thiazolidinone-type CFTR blocker (CFTR(inh)-172) reduced cholera toxin-induced fluid accumulation in mouse intestinal loops. Here, we characterize the efficacy and pharmacodynamics of CFTR(inh)-172 in blocking cAMP and cGMP induced Cl(-)/fluid secretion in rodent and human intestine.

METHODS & RESULTS

CFTR(inh)-172 inhibited cAMP and cGMP agonist induced short-circuit current by >95% in T84 colonic epithelial cells (K(I) approximately 3 micromol/L) and in mouse and human intestinal sheets (K(I) approximately 9 micromol/L). A single intraperitoneal injection of CFTR(inh)-172 (200 microg) blocked intestinal fluid secretion in a rat closed-loop model by >90% for cholera toxin and >70% for STa Escherichia coli toxin. In mice, CFTR(inh)-172 (20 microg) inhibited cholera toxin-induced intestinal fluid secretion by 90% (persistence t(1/2) approximately 10 hours, K(I) approximately 5 microg) and STa toxin by 75% (K(I) approximately 10 microg). Tissue distribution and pharmacokinetic studies indicated intestinal CFTR(inh)-172 accumulation facilitated by enterohepatic circulation. An oral CFTR(inh)-172 preparation reduced fluid secretion by >90% in a mouse open-loop cholera model.

CONCLUSIONS

A small molecule CFTR blocker markedly reduced intestinal ion and fluid secretion caused by cAMP/cGMP-dependent bacterial enterotoxins. CFTR inhibition may thus reduce fluid secretion in infectious secretory diarrheas.

Severe acute diarrhea

Acute diarrhea is commonly caused by an infection. Severe acute diarrhea warrants immediate medical evaluation and hospitalization. Indications for stool studies include fever; bloody diarrhea; recent travel to an endemic area; recent antibiotics; immunosuppression; and occupational risks, such as food handlers. Noninfectious causes include inflammatory bowel disease, radiation enteritis, and intestinal ischemia. Management of severe acute diarrhea includes intravenous fluid rehydration and empiric antibiotics. Use of antidiarrheal agents is controversial when invasive pathogens are suspected.

Diagnosis and treatment of bacterial diarrhea

Diarrheal illness caused by bacterial pathogens is a global health problem and remains one of the most common complaints prompting patients to seek medical care. Strategies to increase the yield of stool culture and new rapid diagnostic tests can improve diagnostic ability. Emerging antimicrobial resistance among the common bacterial causes of diarrhea has made treatment more challenging. Emerging fluoroquinolone resistance is a particular concern. Recent studies of rifaximin, a nonabsorbed antibiotic for the treatment of bacterial diarrhea, have shown favorable results. Rifaximin may represent a much-needed addition to the armamentarium against bacterial agents.