Pro-Survival Pathway Protects from C. difficile Toxin-Mediated Cell Death

There is an urgent need for new non-antibiotic based treatment strategies for Clostridioides difficile infection. C. difficile toxin B (TcdB) is a virulent factor that is essential for causing disease. Here, we investigated whether a survival-signaling pathway could protect against TcdB. We found significant increase in caspase-3 apoptotic activity in intestinal epithelial cells of mice exposed to TcdB. Subsequently, activation of the MIF-CD74-Akt pro-survival signaling pathway blocked TcdB-induced caspase-3 activity and intestinal epithelial cell death. This brief report provides proof-of-concept that targeting pro-survival pathways may represent a unique antibiotic-independent strategy for protecting against C. difficile toxin-mediated cell death.

Clostridioides difficile Infection in Children: Recent Updates on Epidemiology, Diagnosis, Therapy

Clostridioides (formerly Clostridium) difficile is the most important infectious cause of antibiotic-associated diarrhea worldwide and a leading cause of healthcare-associated infection in the United States. The incidence of C. difficile infection (CDI) in children has increased, with 20 000 cases now reported annually, also posing indirect educational and economic consequences. In contrast to infection in adults, CDI in children is more commonly community-associated, accounting for three-quarters of all cases. A wide spectrum of disease severity ranging from asymptomatic carriage to severe diarrhea can occur, varying by age. Fulminant disease, although rare in children, is associated with high morbidity and even fatality. Diagnosis of CDI can be challenging as currently available tests detect either the presence of organism or disease-causing toxin but cannot distinguish colonization from infection. Since colonization can be high in specific pediatric groups, such as infants and young children, biomarkers to aid in accurate diagnosis are urgently needed. Similar to disease in adults, recurrence of CDI in children is common, affecting 20% to 30% of incident cases. Metronidazole has long been considered the mainstay therapy for CDI in children. However, new evidence supports the safety and efficacy of oral vancomycin and fidaxomicin as additional treatment options, whereas fecal microbiota transplantation is gaining popularity for recurrent infection. Recent advancements in our understanding of emerging epidemiologic trends and management of CDI unique to children are highlighted in this review. Despite encouraging therapeutic advancements, there remains a pressing need to optimize CDI therapy in children, particularly as it pertains to severe and recurrent disease.

Drug Repurposing of the Alcohol Abuse Medication Disulfiram as an Anti-Parasitic Agent

Parasitic infections contribute significantly to worldwide morbidity and mortality. Antibiotic treatment is essential for managing patients infected with these parasites since control is otherwise challenging and there are no vaccines available for prevention. However, new antimicrobial therapies are urgently needed as significant problems exist with current treatments such as drug resistance, limited options, poor efficacy, as well as toxicity. This situation is made worse by the challenges of drug discovery and development which is costly especially for non-profitable infectious diseases, time-consuming, and risky with a high failure rate. Drug repurposing which involves finding new use for existing drugs may help to more rapidly identify therapeutic candidates while drastically cutting costs of drug research and development. In this perspective article, we discuss the importance of drug repurposing, review disulfiram pharmacology, and highlight emerging data that supports repurposing disulfiram as an anti-parasitic, exemplified by the major diarrhea-causing parasite Entamoeba histolytica.

COVID-19 and Corticosteroids: Unfamiliar but Potentially Fatal Infections That Can Arise following Short-Course Steroid Treatment

Corticosteroid use is increasing worldwide as recent studies confer survival benefit of corticosteroids in the management of patients with severe COVID-19. Strongyloides and amebic infections are neglected diseases that can progress to catastrophic complications in patients exposed to corticosteroids, even with short treatment courses. To prevent lethal outcomes, clinicians should be aware of the threat these two parasitic infections pose to at-risk patients receiving corticosteroids, especially in the era of COVID-19.

Acute appendicitis in four children with SARS-CoV-2 infection

We describe 4 children (11-17 years in age) at our institution with acute appendicitis in the setting of SARS-CoV-2 infection, suggesting a possible association. Providers should consider testing for this infection in patients with severe gastrointestinal symptoms, in order to take appropriate transmission based precautions, until more is understood.

COP9 signalosome is an essential and druggable parasite target that regulates protein degradation

Understanding how the protozoan protein degradation pathway is regulated could uncover new parasite biology for drug discovery. We found the COP9 signalosome (CSN) conserved in multiple pathogens such as Leishmania, Trypanosoma, Toxoplasma, and used the severe diarrhea-causing Entamoeba histolytica to study its function in medically significant protozoa. We show that CSN is an essential upstream regulator of parasite protein degradation. Genetic disruption of E. histolytica CSN by two distinct approaches inhibited cell proliferation and viability. Both CSN5 knockdown and dominant negative mutation trapped cullin in a neddylated state, disrupting UPS activity and protein degradation. In addition, zinc ditiocarb (ZnDTC), a main metabolite of the inexpensive FDA-approved globally-available drug disulfiram, was active against parasites acting in a COP9-dependent manner. ZnDTC, given as disulfiram-zinc, had oral efficacy in clearing parasites in vivo. Our findings provide insights into the regulation of parasite protein degradation, and supports the significant therapeutic potential of COP9 inhibition.

Role of MIF Cytokine/CD74 Receptor Pathway in Protecting Against Injury and Promoting Repair

Wound healing after an injury is essential for life. An in-depth understanding of the healing process is necessary to ultimately improve the currently limited treatment options for patients suffering as a result of damage to various organs and tissues. Injuries, even the most minor, trigger an inflammatory response that protects the host and activates repair pathways. In recent years, substantial progress has been made in delineating the mechanisms by which inflammatory cytokines and their receptors facilitate tissue repair and regeneration. This mini review focuses on emerging literature on the role of the cytokine macrophage migration inhibitory factor (MIF) and its cell membrane receptor CD74, in protecting against injury and promoting healing in different parts of the body.

Case Report: Lower Gastrointestinal Bleeding due to Entamoeba histolytica Detected Early by Multiplex PCR: Case Report and Review of the Laboratory Diagnosis of Amebiasis

We report a case of Entamoeba histolytica infection in a young man who presented with cerebral infarction and shortly after admission developed bloody diarrhea with fever. A rapid diagnosis of severe E. histolytica colitis was established through the use of a multiplex polymerase chain reaction enteropathogen stool panel. This result was unexpected in a patient native to the United States without known risk factors for amebiasis and negative stool microscopy examination for ova and parasites. Rapid diagnosis allowed prompt initiation of appropriate anti-amebic therapy and ultimately a good outcome in a condition that otherwise carries high morbidity and fatality.

Targeting Parasite-Produced Macrophage Migration Inhibitory Factor as an Antivirulence Strategy With Antibiotic-Antibody Combination to Reduce Tissue Damage

Targeting virulence factors represents a promising alternative approach to antimicrobial therapy, through the inhibition of pathogenic pathways that result in host tissue damage. Yet, virulence inhibition remains an understudied area in parasitology. Several medically important protozoan parasites such as Plasmodium, Entamoeba, Toxoplasma, and Leishmania secrete an inflammatory macrophage migration inhibitory factor (MIF) cytokine homolog, a virulence factor linked to severe disease. The aim of this study was to investigate the effectiveness of targeting parasite-produced MIF as combination therapy with standard antibiotics to reduce disease severity. Here, we used Entamoeba histolytica as the model MIF-secreting protozoan, and a mouse model that mirrors severe human infection. We found that intestinal inflammation and tissue damage were significantly reduced in mice treated with metronidazole when combined with anti-E. histolytica MIF antibodies, compared to metronidazole alone. Thus, this preclinical study provides proof-of-concept that combining antiparasite MIF-blocking antibodies with current standard-of-care antibiotics might improve outcomes in severe protozoan infections.

CD74 Signaling Links Inflammation to Intestinal Epithelial Cell Regeneration and Promotes Mucosal Healing

BACKGROUND & AIMS

The inflammatory response to intestinal damage promotes healing through mechanisms that are incompletely understood. Gene expression of cluster of differentiation 74 (CD74), the receptor for cytokine macrophage migration inhibitory factor, is increased in patients with inflammatory bowel disease (IBD), however, the role of CD74 signaling in intestinal inflammation remains poorly understood. The aim of this study was to determine the functional role of CD74 signaling in intestinal inflammation.

METHODS

We studied the characteristics of CD74 protein expression in human IBD and experimental colitis. The functional role of CD74 signaling in the intestine was investigated using cellular models; wild-type, CD74^-/-, and bone marrow chimera mice; neutralizing anti-CD74 antibodies; flow cytometry; immunohistochemistry; immunofluorescence; immunoblotting; and clustered regularly interspaced short palindromic repeats and associated protein 9 technology.

RESULTS

In IBD patients and experimental colitis, CD74-receptor protein expression was increased in inflamed intestinal tissue, prominently in the crypt epithelial cells. By using distinct but complementary chemical and non-chemically induced mouse models of colitis with genetic and antibody neutralization approaches, we found that CD74 signaling was necessary for gut repair. Mechanistically, we found that the macrophage migration inhibitory factor cytokine, which also is increased in colitis, stimulated the CD74 receptor, enhancing intestinal epithelial cell proliferation through activation of the protein kinase B and the extracellular signal-regulated kinase pathways. Our data also suggest that CD74 signaling in immune cells was not essential for mucosal healing.

CONCLUSIONS

CD74 signaling is strongly activated during intestinal inflammation and protects the host by promoting epithelial cell regeneration, healing, and maintaining mucosal barrier integrity. Enhancing the CD74 pathway may represent a unique therapeutic strategy for promoting healing in IBD.

Purification of Antibodies Against Entamoeba histolytica MIF and Their Use in Analyzing Human and Mouse Samples

Macrophage migration inhibitory factor (MIF) is a proinflammatory and proproliferative cytokine expressed in humans. MIF homologs also exist in many pathogenic protozoans, including Entamoeba, Plasmodium, Toxoplasma, and Leishmania. Production of antibodies against parasite proteins allows for the generation of assays to measure and visualize parasite infection within hosts. In this chapter, we describe how to specifically purify antibodies against Entamoeba histolytica MIF (EhMIF), and subsequently use anti-EhMIF antibodies for ELISA on mouse and human samples and for immunohistochemistry on human tissue. These methods can be applied to any protein for high-quality antibody purification.

Parasite-Produced MIF Cytokine: Role in Immune Evasion, Invasion, and Pathogenesis

Protozoan parasites represent a major threat to health and contribute significantly to morbidity and mortality worldwide, especially in developing countries. This is further compounded by lack of effective vaccines, drug resistance and toxicity associated with current therapies. Multiple protozoans, including Plasmodium, Entamoeba, Toxoplasma, and Leishmania produce homologs of the cytokine MIF. These parasite MIF homologs are capable of altering the host immune response during infection, and play a role in immune evasion, invasion and pathogenesis. This minireview outlines well-established and emerging literature on the role of parasite MIF homologs in disease, and their potential as targets for therapeutic and preventive interventions.

Entamoeba Species in South Africa: Correlations With the Host Microbiome, Parasite Burdens, and First Description of Entamoeba bangladeshi Outside of Asia

Background

Diarrhea is frequent in communities without clean water, which include low-income South African populations in Giyani and Pretoria. In these populations, the amount of diarrhea caused by Entamoeba histolytica, inclusive of all ages, sexes, and human immunodeficiency virus status, is uncertain. Infection with E. histolytica can modulate the host microbiota, and a key species indicative of this is the Prevotella copri pathobiont.

Methods

A cross-sectional study of patients attending gastroenterology clinics was conducted to determine the frequency and burden of 4 Entamoeba species and P. copri.

Results

Entamoeba species were present in 27% of patients (129/484), with E. histolytica detected in 8.5% (41), E. dispar in 8% (38), E. bangladeshi in 4.75% (23), and E. moshkovskii in 0%. This is the first description of E. bangladeshi outside Bangladesh. In E. histolytica-positive samples, the levels of both the parasite and P. copri were lower in nondiarrheal samples, validating the results of a study in Bangladesh (P = .0034). By contrast, in E. histolytica-negative samples positive for either of the nonpathogenic species E. dispar or E. bangladeshi, neither P. copri nor Entamoeba levels were linked to gastrointestinal status.

Conclusions

Nonmorphologic identification of this parasite is essential. In South Africa, 3 morphologically identical Entamoeba were common, but only E. histolytica was linked to both disease and changes in the microbiota.

A Review of the Global Burden, New Diagnostics, and Current Therapeutics for Amebiasis

Amebiasis, due to the pathogenic parasite Entamoeba histolytica, is a leading cause of diarrhea globally. Largely an infection of impoverished communities in developing countries, amebiasis has emerged as an important infection among returning travelers, immigrants, and men who have sex with men residing in developed countries. Severe cases can be associated with high case fatality. Polymerase chain reaction–based diagnosis is increasingly available but remains underutilized. Nitroimidazoles are currently recommended for treatment, but new drug development to treat parasitic agents is a high priority. Amebiasis should be considered before corticosteroid therapy to decrease complications. There is no effective vaccine, so prevention focuses on sanitation and access to clean water. Further understanding of parasite biology and pathogenesis will advance future targeted therapeutic and preventative strategies.

Fulminant Amebic Colitis after Corticosteroid Therapy: A Systematic Review

BACKGROUND

Amebic colitis, caused by intestinal infection with the parasite, Entamoeba histolytica, is a common cause of diarrhea worldwide. Fulminant amebic colitis is the most devastating complication of this infection, associated with both high mortality and morbidity. We conducted a review of the English literature to describe cases of fulminant amebic colitis associated with exposure to corticosteroid medications in order to identify the risk factors for poor outcome and determine difficulties in diagnosis and treatment.

METHODOLOGY AND PRINCIPAL FINDINGS

Articles reporting severe and fulminant forms of amebic colitis between 1991 and 2016 were collected. 525 records were screened to identify 24 cases for qualitative analysis associated with corticosteroid use. Cases arose from areas of high endemicity or travel to such areas. Most cases (14 of 24, 58%) were given corticosteroids for initially misdiagnosed colitis, mainly inflammatory bowel, resulting in rapid progression of disease. Nearly half of all cases underwent surgical intervention, and 25% of cases died, despite all patients eventually receiving treatment with metronidazole. The odds of death did not differ significantly by prior misdiagnosis, co-morbidities, bowel perforation or need for surgery.

CONCLUSIONS AND SIGNIFICANCE

Infection with E. histolytica should be considered prior to the administration of corticosteroids, in particular for patients residing in endemic areas or those with appropriate travel history, especially prior to the diagnosis of inflammatory bowel disease. The development of preventative and treatment interventions are needed to improve outcomes of fulminant disease.

Multidrug resistant Kluyvera ascorbata septicemia in an adult patient: a case report

Introduction

Kluyvera ascorbata has become increasingly significant due to its potential to cause a wide range of infections, as well as its ability to transfer gene encoding for CTX-M- type extended spectrum B-lactamases (ESBLs) to other Enterobacteriaceae.

Case presentation

We report the case of a 64-year-old African-American male diagnosed with severe sepsis due to a multidrug resistant Kluyvera ascorbata, which was isolated from his blood. He was treated with meropenem and had a favorable outcome.

Conclusion

To the best of our knowledge, this is the first case report of a multidrug resistant Kluyvera ascorbata isolated from the blood in an adult patient with sepsis.

Distribution of nosocomial organisms and their resistance patterns in the intensive care unit of the University Hospital of the West Indies, Kingston, Jamaica

OBJECTIVES

To determine the distribution and antibiotic susceptibility patterns of nosocomial pathogens in the Intensive Care Unit (ICU) at the University Hospital of the West Indies (UHWI).

METHODS

A retrospective review of the laboratory records of all ICU patients from 2002-2004 was done. All organisms isolated from blood, urine, sputum, wound swabs and CVP tips were recorded. Sensitivity reports for organisms isolated in 2004 were also obtained. Results were analysed according to source of isolates and type of infection.

RESULTS

Gram-negative organisms account for the majority oflCU isolates and show resistance to multiple antibiotics. The common Gram negative pathogens in the ICU are Pseudomonas aeruginosa, Acinetobacter spp and Stenotrophomonas maltophilia while the common Gram positive nosocomial organisms are Group D Streptococcus and coagulase negative Staphylococcus.

CONCLUSION

The organisms isolated in the ICU at the UHWI are similar to those isolated in many ICUs all over the world. Surveillance data are necessary to monitor nosocomial pathogens and their resistance patterns to guide empirical antibiotic therapy.

Coagulase negative Staphylococci from blood cultures: contaminants or pathogens?

Detailed clinical data, underlying conditions, inflammatory indices and microbiological parameters in 60 patients who had pure growth of coagulase negative staphylococci from their blood culture specimens at the University Hospital of the West Indies, Jamaica, were analyzed and the clinical significance of the isolates ascertained using standard criteria. This study was undertaken between April and September 2003. The isolates were true pathogens of bloodstream infections in only 5 of the 60 patients (8.4%). In the vast majority ie 44 of 60 (73.3%) they were mere blood culture contaminants and in 11 (18.3%), the clinical significance could not be ascertained Fifteen of the 44 patients (34%) with contaminating coagulase negative staphylococci were treated with specific anti-staphylococcal antibiotics; 5 (11.4%) with vancomycin. Although there has been a relative increase of coagulase negative staphylococcal infections including bloodstream infections in recent years, the organisms still remain the most common contaminants in blood cultures. Over 70% of isolates were contaminants in this study which is similar to that in a number of such studies in other parts of the world The findings underline the need for careful evaluation of coagulase negative staphylococci isolated from blood cultures before instituting therapy to avoid unnecessary use of antibiotics, especially vancomycin, and the consequent increase of antibiotic resistance in hospitals.