Emerging infectious colitis

Mitogen-Activated Protein Kinases (MAPKs) and Enteric Bacterial Pathogens: A Complex Interplay

Diverse extracellular and intracellular cues activate mammalian mitogen-activated protein kinases (MAPKs). Canonically, the activation starts at cell surface receptors and continues via intracellular MAPK components, acting in the host cell nucleus as activators of transcriptional programs to regulate various cellular activities, including proinflammatory responses against bacterial pathogens. For instance, binding host pattern recognition receptors (PRRs) on the surface of intestinal epithelial cells to bacterial pathogen external components trigger the MAPK/NF-κB signaling cascade, eliciting cytokine production. This results in an innate immune response that can eliminate the bacterial pathogen. However, enteric bacterial pathogens evolved sophisticated mechanisms that interfere with such a response by delivering virulent proteins, termed effectors, and toxins into the host cells. These proteins act in numerous ways to inactivate or activate critical components of the MAPK signaling cascades and innate immunity. The consequence of such activities could lead to successful bacterial colonization, dissemination, and pathogenicity. This article will review enteric bacterial pathogens' strategies to modulate MAPKs and host responses. It will also discuss findings attempting to develop anti-microbial treatments by targeting MAPKs.

Increased Seroprevalence of Campylobacter jejuni, but not HEV, in healthcare workers in gastroenterological endoscopy

BACKGROUND

The exposure of healthcare workers (HCW) to fecal-orally transmitted pathogens like hepatitis E Virus (HEV), Campylobacter jejuni or Helicobacter pylori is still not known. The potential risk for employees or patients to acquire these infections through asymptomatic infected healthcare personnel has not yet been studied. Physicians and nurses in gastroenterology working in endoscopic workspaces were recruited. Employees from cardiology, presumed to possess a lower exposure, served as controls. The cytomegalovirus (CMV) seroprevalence was analyzed as a control pathogen without fecal-oral route of transmission. This study provides an objective view onto the potential exposure risk for HCW and patients in endoscopic workspaces. We hypothesize that HCW in gastroenterological endoscopy show a higher seroprevalence for fecal-oral pathogens like HEV, C. jejuni and H. pylori compared to HCW in cardiology.

OBJECTIVE

Primary objective was the assessment of antibody titers against HEV, C. jejuni and H. pylori in serum of HCW from gastroenterological endoscopy as well as cardiology. As a secondary objective we analyzed the seroprevalence against CMV.

METHODS

65 HCW were from gastroenterological endoscopy (n=42) and cardiology (n=23) in three medical centers in the German federal states of Brandenburg, Hamburg and Schleswig-Holstein and were prospectively studied. Antibody titers were determined via ELISA in serum.

RESULTS

HCW in gastroenterological endoscopy showed a significantly higher C. jejuni seroprevalence for IgG (19.1 %) compared to HCW from the field of cardiology (8.7 %; p=0.04). IgA titers against C. jejuni were negligible. HEV seroprevalence for IgG did not differ significantly between HCW in gastroenterological endoscopy (7.1 %) and cardiology (8.7 %), respectively. IgA and IgM titers against HEV were also negligible. All other antibody titers against CMV and H. pylori showed no significant difference.

CONCLUSIONS

Only the C. jejuni seroprevalence was significantly increased in HCW from the field of gastroenterological endoscopy. HEV seroprevalence showed no differences. The results for CMV and H. pylori were without pathological findings. However, there is no elevated risk for HEV exposure in medical staff working at an endoscopy unit, but for C. jejuni the protective measures might need to be improved.

Mapping of etiologies of computed tomography-proven acute colitis: a prospective cohort study

Our objective was to describe the etiologies of acute colitis and to identify patients who require diagnostic endoscopy. Patients with symptoms of gastrointestinal infection and colonic inflammation on CT were prospectively included. Those immunosuppressed, with history of colorectal cancer or inflammatory bowel disease (IBD), were excluded. Microbiological analysis of the feces was performed using PCR assays BD-Max and FilmArray (GI panel,) and fecal cultures. Fecal calprotectin was determined. Patients with negative BD-Max underwent colonoscopy. One hundred and seventy-nine patients were included. BD-Max was positive in 93 patients (52%) and FilmArray in 108 patients (60.3%). Patients with infectious colitis (n = 103, 57.5%) were positive for Campylobacter spp. (n = 57, 55.3%), Escherichia coli spp. (n = 8, 7.8%), Clostridioides difficile (n = 23, 22.3%), Salmonella spp. (n = 9, 8.7%), viruses (n = 7, 6.8%), Shigella spp. (n = 6, 5.8%), Entamoeba histolytica (n = 2, 1.9%) and others (n = 4, 3.9%). Eighty-six patients underwent colonoscopy, which was compatible with ischemic colitis in 18 patients (10.1%) and IBD in 4 patients (2.2%). Fecal calprotectin was elevated in all patients, with a mean concentration of 1922.1 ± 2895.6 μg/g, and was the highest in patients with IBD (8511 ± 9438 μg/g, p < 0.001). After exclusion of patients with infectious etiology, a fecal calprotectin > 625 μg/g allowed identifying patients with IBD with an area under ROC curve of 85.1%. To conclude, computed tomography-proven colitis was of infectious etiology in 57.5% of patients. The main pathogens identified were Campylobacter spp. (55.3%), Clostridioides difficile (22.3%) and Salmonella spp. (8.7%). Ischemic colitis (10.1%) and IBD (2.2%) were seldom represented. No colorectal cancer was found.

Characterization of Salmonella spp. and E. coli Strains Isolated from Wild Carnivores in Janos Biosphere Reserve, Mexico

Simple Summary

Emerging diseases (EIDs) represent a constant challenge in public health. With the recent emergence of new pathogens, some questions about the mechanisms and sites where they are generated have aroused interest. Natural environments could be the sites where pathogenic microorganisms find the conditions to generate new variants. It has been established that approximately 60.3% of EIDs are caused by potentially zoonotic pathogens, of which more than half are thought to have originated from wild individuals. In this aspect, carnivores can play an important role in the dynamics of various diseases, since there are species that are widely distributed, roam large areas, and can be carriers of a wide range of microorganisms, some of which are zoonotic. The results obtained in this work show that different species of wild carnivores can be carriers of atypical strains of pathogenic microorganisms, which shows that natural environments can represent important sites for the study of EIDs.

Abstract

Enterobacteriaceae are considered one the most important zoonotic pathogens. In this study, we analyzed the characteristics of E. coli and Salmonella spp. strains present in carnivores from Janos Biosphere Reserve, Mexico. These microorganisms had been isolated from a wide range of domestic and free-range animals, including wild carnivores. Fifty-five individuals were sampled, and the presence of Salmonella and E. coli was determined by bacteriological standard methods. Strains isolated were characterized by molecular methods and in vitro infection assays. Eight different species of carnivores were captured, including coyotes (Canis latrans), gray fox (Urocyon cinereoargenteus), desert foxes (Vulpes macrotis), striped skunks (Mephitis mephitis), hooded skunks (Mephitis macroura), lynxes (Lynx rufus), raccoons (Procyon lotor), and badgers (Taxidea taxus). Salmonella spp. and E. coli were isolated from four species of carnivores. Five Salmonella spp. strains were isolated, and their molecular characterization revealed in three of them the presence of fimbrial and virulence genes associated with cell invasion. In vitro evaluation of these strains showed their capability to invade human Hep2 cells. Sixty-one E. coli strains were isolated; different serotypes and phylogroups were observed from these strains. Additionally, the presence of virulence genes showed differently.

Identification and evaluation of protection effect of B-cell immunodominant epitopes of campylobacter jejuni PEB1

To provide detail data for Campylobacter jejuni (C.jejuni) vaccine research, this study performed epitope prediction analysis technology to screen the B cell immunodominant epitopes of C. jejuni adhesion protein PEB1 and evaluated the immunoprotective effect. The overlapping peptides were synthesized and B-cell immunodominant epitopes of PEB1 were identified by ELISA. BALB/c mice were immunized with the immunodominant epitopes of PEB1 conjugated with KLH plus CFA/IFA. The titers for immunodominant peptide antiserum against PEB1 were detected by ELISA. The bacterial colonization and the relative expression level of TNF-α were analyzed after the mice challenged with C. jejuni 11,168. The function of antibody induced by immunodominant PEB1 epitopes were performed by opsonophagocytic killing. The results showed that PEB1_55-72aa, PEB1_97-114aa, PEB1_211-228aa were the immunodominant peptides and could induce strong B cell mediated humoral immunity response. Antiserum from the immunodominant peptides group significantly enhanced opsonize phagocytosis than CFA/IFA group (P<0.01). Both the bacterial burdens and the TNF-α expression level in the immunodominant peptides groups were significantly lower than those in the control group (P<0.01). Moreover, the immune protective effect of the three immunodominant peptides depended on the B cell immunity response in vivo study. In conclusion, three specific B cell immunodominant epitopes with good immunogenicity and immunoprotection efficacy were successfully identified, indicating that could be used in the anti- C. jejuni vaccine research and development.

Causes of hematochezia and hemorrhagic antibiotic-associated colitis in children and adolescents

Diseases causing hematochezia range from benign to potentially life-threatening. Systematic pediatric data on the causes of hematochezia are scarce. We studied the underlying causes and long-term outcome of hematochezia in children. We further investigated the relevance of antibiotic-associated hemorrhagic colitis in children, especially if caused by Klebsiella oxytoca.Infants, children, and adolescents with hematochezia were recruited prospectively. Patients were grouped according to age (<1 year, 1-5 years, 6-13 years, >14 years). In addition to routine diagnostics, K oxytoca stool culture and toxin analysis was performed. We collected data on history, laboratory findings, microbiological diagnostic, imaging, final diagnosis, and long-term outcome.We included 221 patients (female 46%; age 0-19 years). In 98 (44%), hematochezia was caused by infectious diseases. Endoscopy was performed in 30 patients (13.6%). No patient died due to the underlying cause of hematochezia. The most common diagnoses according to age were food protein-induced proctocolitis in infants, bacterial colitis in young children, and inflammatory bowel disease in children and adolescents. Seventeen (7.7%) had a positive stool culture for K oxytoca. Antibiotic-associated colitis was diagnosed in 12 (5%) patients: 2 caused by K oxytoca and 2 by Clostridium difficile; in the remaining 8 patients, no known pathobiont was identified.Infections were the most common cause of hematochezia in this study. In most patients, invasive diagnostic procedures were not necessary. Antibiotic-associated hemorrhagic colitis caused by K oxytoca was an uncommon diagnosis in our cohort. Antibiotic-associated colitis with hematochezia might be caused by pathobionts other than C difficile or K oxytoca.

Genomics and Foodborne Viral Infections

Foodborne viral illness, resulting from the consumption of contaminated food or water containing pathogenic viruses, remains a major public health problem globally with substantial economic impact. Major challenges regarding recognizing, detecting, characterizing, and effectively responding to foodborne viral threats to health exist. Adequate health crisis management is largely dependent on early detection of potential public health threats, which is hampered by changing trends in disease outbreaks, from localized clusters of disease in confined populations to dispersed outbreaks with excellent opportunity for further transmission. In addition, no precise and consistent global baseline syndrome and diagnostic surveillance information exists. An integrated multidisciplinary approach with a combination of sustained pathogen syndrome and diagnostic surveillance, genomics-based, and standardized global analytical networks gathering clinical, epidemiological and genetic data alike would be required to understand the dynamics of foodborne viral infection and to mitigate potential effects of future threats. A huge global effort in virus syndrome and diagnostic surveillance may be justified in the light of global health impact in general, and timely with the development of new metagenomics tools that hold the promise of not only identifying viral pathogens, but possibly the complete microbiome in a single assay.

Antimicrobial therapy of acute diarrhoea: a clinical review

Diarrhoea is one of the most commonly occurring diseases. This article presents a review of the current state of the treatment of acute infectious diarrhoea, as well as of the most important pathogens. The general principles of the therapy of diarrhoea are exemplified, followed by a description of the targeted antimicrobial therapy of the most important bacterial gastrointestinal infections, including salmonellosis, shigellosis and Campylobacter infections, as well as infections with pathogenic Escherichia coli strains, yersiniosis and cholera. Diarrhoea caused by toxigenic Clostridium difficile strains has increased in incidence and in severity. These infections will therefore be described in detail, including important new aspects of treatment. Symptomatic therapy is still the most important component of the treatment of infectious diarrhoea. However, empirical antibiotic therapy should be considered for severely ill patients with a high frequency of stools, fever, bloody diarrhoea, underlying immune deficiency, advanced age or significant comorbidities. Increasing resistance, in particular against fluoroquinolones, must be taken into consideration. Therapy with motility inhibitors is not recommended for Shiga toxin-producing Escherichia coli (STEC) infections, Clostridium difficile infections (CDI), and severe colitis. The macrocyclic antibiotic fidaxomicin can reduce the rate of recurrent disease in CDI. Furthermore, evidence for the benefits of faecal microbiota transplantation as a treatment option for multiple recurrences of CDI is increasing. In conclusion, the treatment of acute diarrhoea is still primarily supportive. General empirical antibiotic therapy for acute diarrhoea is not evidence-based.

Helicobacter pullorum isolated from fresh chicken meat: antibiotic resistance and genomic traits of an emerging foodborne pathogen

Meat and meat products are important sources of human intestinal infections. We report the isolation of Helicobacter pullorum strains from chicken meat. Bacteria were isolated from 4 of the 17 analyzed fresh chicken meat samples, using a membrane filter method. MIC determination revealed that the four strains showed acquired resistance to ciprofloxacin; one was also resistant to erythromycin, and another one was resistant to tetracycline. Whole-genome sequencing of the four strains and comparative genomics revealed important genetic traits within the H. pullorum species, such as 18 highly polymorphic genes (including a putative new cytotoxin gene), plasmids, prophages, and a complete type VI secretion system (T6SS). The T6SS was found in three out of the four isolates, suggesting that it may play a role in H. pullorum pathogenicity and diversity. This study suggests that the emerging pathogen H. pullorum can be transmitted to humans by chicken meat consumption/contact and constitutes an important contribution toward a better knowledge of the genetic diversity within the H. pullorum species. In addition, some genetic traits found in the four strains provide relevant clues to how this species may promote adaptation and virulence.

Active targeted drug delivery for microbes using nano-carriers

Although vaccines and antibiotics could kill or inhibit microbes, many infectious diseases remain difficult to treat because of acquired resistance and adverse side effects. Nano-carriers-based technology has made significant progress for a long time and is introducing a new paradigm in drug delivery. However, it still has some challenges like lack of specificity toward targeting the infectious site. Nanocarriers utilized targeting ligands on their surface called 'active target' provide the promising way to solve the problems like accelerating drug delivery to infectious areas and preventing toxicity or side-effects. In this mini review, we demonstrate the recent studies using the active targeted strategy to kill or inhibit microbes. The four common nano-carriers (e.g. liposomes, nanoparticles, dendrimers and carbon nanotubes) delivering encapsulated drugs are introduced.

Study of the antibacterial activity in the gas phase of a chemical formulation for household waste management

The aim of this study was to formulate a product (microbicide mixture) that could slow down the bacterial proliferation during the storage of household waste. We used harmless and natural components, known for their antimicrobial properties, in the liquid phase at direct contact with the microbes. The antimicrobial activity of the microbicide mixture formulated was evaluated over a range of concentration in two types of tests, in the liquid and in the gas phase. Once the efficacy of antimicrobial agent in the liquid phase in direct contact with the microbe (Escherichia coli) was confirmed, we adopted a new approach to evaluate the effect of the vapour phase both on the microbes' growth and on its duration. Here, we show that the perfect combination that gives rise to an antimicrobial mixture useful to control microbial growth (Staphylococcus aureus, Escherichia coli, Debaryomyces hansenii or Penicillium citrinum) up to 4 weeks is the one between more volatile agents (2-propanol and limonene) and a less volatile agent (cinnamaldehyde). The pleasant smell as well as the synergic antibacterial and antifungal function of the natural components of this mixture makes it attractive in domestic waste management.

SIGNIFICANCE AND IMPACT OF THE STUDY

The novelty of this work is two-fold: on the one hand, to test various antimicrobial components of different volatility in a single microbicide mixture, and on the other, to study antimicrobial activity in the gas phase, other than the liquid phase. While previous authors tested the components individually as antimicrobial agents in the liquid phase at direct contact with the microbes, we tested them altogether as a mixture both in the liquid and in gas phase. The aim of this study was to disinfect small environments, such as garbage containers, by favouring the diffusion of the vapour phase to avoid the growth of microbes. This study proposes a new approach in the management and storage of household waste by inhibiting bacterial proliferation in the garbage can.

The microbes we eat: abundance and taxonomy of microbes consumed in a day's worth of meals for three diet types

Far more attention has been paid to the microbes in our feces than the microbes in our food. Research efforts dedicated to the microbes that we eat have historically been focused on a fairly narrow range of species, namely those which cause disease and those which are thought to confer some “probiotic” health benefit. Little is known about the effects of ingested microbial communities that are present in typical American diets, and even the basic questions of which microbes, how many of them, and how much they vary from diet to diet and meal to meal, have not been answered.

We characterized the microbiota of three different dietary patterns in order to estimate: the average total amount of daily microbes ingested via food and beverages, and their composition in three daily meal plans representing three different dietary patterns. The three dietary patterns analyzed were: (1) the Average American (AMERICAN): focused on convenience foods, (2) USDA recommended (USDA): emphasizing fruits and vegetables, lean meat, dairy, and whole grains, and (3) Vegan (VEGAN): excluding all animal products. Meals were prepared in a home kitchen or purchased at restaurants and blended, followed by microbial analysis including aerobic, anaerobic, yeast and mold plate counts as well as 16S rRNA PCR survey analysis.

Based on plate counts, the USDA meal plan had the highest total amount of microbes at 1.3 × 10⁹ CFU per day, followed by the VEGAN meal plan and the AMERICAN meal plan at 6 × 10⁶ and 1.4 × 10⁶ CFU per day respectively. There was no significant difference in diversity among the three dietary patterns. Individual meals clustered based on taxonomic composition independent of dietary pattern. For example, meals that were abundant in Lactic Acid Bacteria were from all three dietary patterns. Some taxonomic groups were correlated with the nutritional content of the meals. Predictive metagenome analysis using PICRUSt indicated differences in some functional KEGG categories across the three dietary patterns and for meals clustered based on whether they were raw or cooked.

Further studies are needed to determine the impact of ingested microbes on the intestinal microbiota, the extent of variation across foods, meals and diets, and the extent to which dietary microbes may impact human health. The answers to these questions will reveal whether dietary microbes, beyond probiotics taken as supplements—i.e., ingested with food—are important contributors to the composition, inter-individual variation, and function of our gut microbiota.