Epidemiology of clinically relevant Entamoeba spp. (E. histolytica/dispar/moshkovskii/bangladeshi): A cross sectional study from North India

A high-dimensional platform for observing neutrophil-parasite interactions

Diarrheal diseases with infectious etiology remain a major cause of death globally, particularly in low-income countries. Entamoeba histolytica is a pathogenic protozoan parasite that is the causative agent of amebiasis. Amebiasis has a wide presentation in clinical severity with many factors, including the bacterial microbiota, contributing to this variation. The innate immune response also plays a critical role in regulating the severity of E. histolytica infection, with neutrophils reported to have a protective role. Despite this, the precise mechanism of how neutrophils mediate amebic killing is poorly understood. Thus, modern platforms that allow for inquiry of granulocyte-ameba interactions will increase our understanding of this disease. Herein, we describe an assay for neutrophil killing of E. histolytica by utilizing high-dimensional spectral flow cytometry. Neutrophils were isolated from wild-type 5-week-old C57BL/6 mice and co-cultured with E. histolytica at various multiplicity of infections (MOIs). After co-culture, neutrophils and E. histolytica were stained for spectral flow cytometry. Cell populations were identified using surface markers and fluorescence minus one (FMO) controls. We have previously shown that animals colonized with a component of the human microbiota, Clostridium scindens, were protected from E. histolytica. This protection was associated with elevated neutrophil count. Here, we explored amebic killing capacity and observed that neutrophils from animals with C. scindens possessed heightened amebic killing compared with controls. Thus, this study establishes a novel platform that can provide an in-depth analysis of granulocyte-parasite interactions in various contexts, including during alteration of the intestinal microbiota.IMPORTANCEThe tools for studying host immune cell-E. histolytica interactions are limited. Factors, such as parasite heterogeneity, infectivity, and difficulties with culture systems and animal models, make interrogation of these interactions challenging. Thus, Entamoeba researchers can benefit from next-generation models that allow for the analysis of both host and parasite cells. Here, we demonstrate the use of a novel platform that allows for the determination of parasite-host cell interactions and customizable high-dimensional phenotyping of both populations. Indeed, spectral flow cytometry can approach >40 markers on a single panel and can be paired with custom-developed parasite antibodies that can be conjugated to fluorochromes via commercially available kits. This platform affords researchers the capability to test highly precise hypotheses regarding host-parasite interactions.

Amebic liver abscess: An update

Amebic liver abscess (ALA) is still a common problem in the tropical world, where it affects over three-quarters of patients with liver abscess. It is caused by an anaerobic protozoan Entamoeba hystolytica, which primarily colonises the cecum. It is a non-suppurative infection of the liver consisting primarily of dead hepatocytes and cellular debris. People of the male gender, during their reproductive years, are most prone to ALA, and this appears to be due to a poorly mounted immune response linked to serum testosterone levels. ALA is more common in the right lobe of the liver, is strongly associated with alcohol consumption, and can heal without the need for drainage. While majority of ALA patients have an uncomplicated course, a number of complications have been described, including rupture into abdomino-thoracic structures, biliary fistula, vascular thrombosis, bilio-vascular compression, and secondary bacterial infection. Based on clinico-radiological findings, a classification system for ALA has emerged recently, which can assist clinicians in making treatment decisions. Recent research has revealed the role of venous thrombosis-related ischemia in the severity of ALA. Recent years have seen the development and refinement of newer molecular diagnostic techniques that can greatly aid in overcoming the diagnostic challenge in endemic area where serology-based tests have limited accuracy. Metronidazole has been the drug of choice for ALA patients for many years. However, concerns over the resistance and adverse effects necessitate the creation of new, safe, and potent antiamebic medications. Although the indication of the drainage of uncomplicated ALA has become more clear, high-quality randomised trials are still necessary for robust conclusions. Percutaneous drainage appears to be a viable option for patients with ruptured ALA and diffuse peritonitis, for whom surgery represents a significant risk of mortality. With regard to all of the aforementioned issues, this article intends to present an updated review of ALA.

Creep in nitroimidazole inhibitory concentration among the Entamoeba histolytica isolates causing amoebic liver abscess and screening of andrographolide as a repurposing drug

Infections by Entamoeba histolytica (E. histolytica) lead to considerable morbidity and mortality worldwide and treatment is reliant on a single class of drugs, nitroimidazoles. Treatment failures and intermittent reports of relapse from different parts of world indicate towards development of clinical drug resistance. In the present study, susceptibility testing of clinical isolates of E. histolytica was carried against metronidazole and tinidazole. Additionally, anti-amoebic property of active compounds of Andrographis paniculata was also evaluated. Prevalence of metronidazole resistance gene (nim) in patients attending hospital was also done to get comprehensive insight of present situation of drug resistance in E. histolytica. Mean inhibitory concentration 50 (IC50) value of E. histolytica isolates against metronidazole and tinidazole was 20.01 and 16.1 µM respectively. Andrographolide showed minimum mean IC50 value (3.06 µM). Significant percentage inhibition of E. histolytica isolates by andrographolide was seen as compared to metronidazole (p = 0.0495). None of E. histolytica isolates showed presence of nim gene. However, in stool samples from hospital attending population, prevalence of nimE gene was found to be 76.6% (69/90) and 62.2% (56/90) in diarrheal and non-diarrheal samples respectively. Inhibitory concentration of commonly used nitroimidazoles against clinical isolates of E. histolytica are on rise. Percentage inhibition of E. histolytica isolates by andrographolide was significantly higher than control drug metronidazole.

Protozoan predation as a driver of diversity and virulence in bacterial biofilms

Protozoa are eukaryotic organisms that play a crucial role in nutrient cycling and maintaining balance in the food web. Predation, symbiosis and parasitism are three types of interactions between protozoa and bacteria. However, not all bacterial species are equally susceptible to protozoan predation as many are capable of defending against predation in numerous ways and may even establish either a symbiotic or parasitic life-style. Biofilm formation is one such mechanism by which bacteria can survive predation. Structural and chemical components of biofilms enhance resistance to predation compared to their planktonic counterparts. Predation on biofilms gives rise to phenotypic and genetic heterogeneity in prey that leads to trade-offs in virulence in other eukaryotes. Recent advances, using molecular and genomics techniques, allow us to generate new information about the interactions of protozoa and biofilms of prey bacteria. This review presents the current state of the field on impacts of protozoan predation on biofilms. We provide an overview of newly gathered insights into (i) molecular mechanisms of predation resistance in biofilms, (ii) phenotypic and genetic diversification of prey bacteria, and (iii) evolution of virulence as a consequence of protozoan predation on biofilms.

British Association of Sexual Health and HIV (BASHH) United Kingdom national guideline for the management of sexually transmitted enteric infections 2023

This is the first British Association of Sexual Health and HIV (BASHH) national guideline for the management of sexually transmitted enteric infections (STEI). This guideline is primarily aimed for level 3 sexual health clinics; however, it may also be applicable to other settings such as primary care or other hospital departments where individuals with STEI may present. This guideline makes recommendations on testing, management, partner notification and public health control of STEI.

Global burden and trends of the Entamoeba infection-associated diseases from 1990 to 2019: An observational trend study

BACKGROUND

Entamoeba infection-associated diseases (EIADs) in humans are a worldwide public health problem, but there is a lack of a global picture of EIADs, which is vital to prevention and control.

METHODS

We applied 2019 Global Burden of Disease (GBD) data collected from multiple sources at global, national and regional levels. The disability-adjusted life years (DALYs) with corresponding 95% uncertainty intervals (95% UIs) were extracted as the main measure of the burden of EIADs. The Joinpoint regression model was used to estimate the trends of age-standardised DALY rates by age, sex, geographical region, and sociodemographic index (SDI). Besides, a generalized linear model was conducted to analyze the influence of sociodemographic factors on the DALY rate of EIADs.

RESULTS

In 2019, there were 2,539,799 (95% UI 850,865-6,186,972) DALY cases attributable to Entamoeba infection, and the global age-standardised DALY rate of EIADs was 36.77/100,000 (95% UI: 12.03-90.49). Although over the past 30 years, the age-standardised DALY rate of EIADs presented significantly declining trends [average annual percent change (AAPC) = -3.79%, 95% CI: -4.05% - -3.53%], it has remained a heavy burden among the age group of <5 years (257.43/100,000, 95% UI: 67.73-676.78) and the low SDI regions (100.47/100,000, 95% UI: 32.27-249.09). The age-standardized DALY rate in high-income North America and Australia had an increasing trend (AAPC = 0.38%, 95% CI: 0.47% - 0.28% and 0.38%, 95% CI: 0.46% - 0.29%, respectively). Furthermore, the DALY rates in high SDI regions showed statistically significant increasing trends among the age groups of 14-49, 50-69 years and 70+ years, with AAPCs of 1.01% (95% CI: 0.87% - 1.15%), 1.58% (95% CI: 1.43% - 1.73%), and 2.93% (95% CI: 2.58% - 3.29%), respectively.

CONCLUSIONS

Over the past 30 years, the burden of EIADs has declined significantly. However, it has still caused a high burden in the low SDI regions and the age group of <5 years. At the same time, in adults and the elderly of the high SDI regions, the increasing trends of Entamoeba infection-associated burden should also be given more attention.

Commensal Intestinal Protozoa-Underestimated Members of the Gut Microbial Community

The human gastrointestinal microbiota contains a diverse consortium of microbes, including bacteria, protozoa, viruses, and fungi. Through millennia of co-evolution, the host-microbiota interactions have shaped the immune system to both tolerate and maintain the symbiotic relationship with commensal microbiota, while exerting protective responses against invading pathogens. Microbiome research is dominated by studies describing the impact of prokaryotic bacteria on gut immunity with a limited understanding of their relationship with other integral microbiota constituents. However, converging evidence shows that eukaryotic organisms, such as commensal protozoa, can play an important role in modulating intestinal immune responses as well as influencing the overall health of the host. The presence of several protozoa species has recently been shown to be a common occurrence in healthy populations worldwide, suggesting that many of these are commensals rather than invading pathogens. This review aims to discuss the most recent, conflicting findings regarding the role of intestinal protozoa in gut homeostasis, interactions between intestinal protozoa and the bacterial microbiota, as well as potential immunological consequences of protozoa colonization.

Prevalence of Amoebiasis and Associated Complications in India: A Systematic Review

PURPOSE

Intestinal protozoan parasites are responsible for diarrheal diseases causing significant morbidity and mortality. Entamoeba histolytica is the principle protozoan parasite associated with diarrheal infections. The infection is often associated with inaccessibility to clean drinking water and poor sanitary conditions in low- and middle-income countries including India. A comprehensive systematic review was performed to evaluate a reliable nationwide estimate for prevalence and geographic distribution of amoebiasis in India and the complications associated with it.

METHODS

We used the PRISMA guidelines to perform a systematic review and meta-analysis of articles published between the year 2001-2020. Two English language databases PubMed and Web of Science were searched to achieve relevant studies.

RESULTS

Initial searches resulted in 467 studies out of which 64 eligible articles involving data from 289,659 human subjects from 12 states and 4 union territories were included in the final analysis. Prevalence of amoebiasis ranged from 3-23% in asymptomatic population, 0.64-11% in symptomatic patients and 1-17.5% in HIV-infected patients. Highest prevalence was seen in Tamil Nadu, Andaman Nicobar Island and North East India. Extra intestinal invasion of Entamoeba histolytica leading to complications such as amoebic liver abscess, amoebic colitis, colonic perforation and ameboma were also reported. Such complications have the potential to increase healthcare burden and may prove to be fatal.

CONCLUSION

Amoebiasis remains a significant public health issue in India responsible for diarrheal diseases causing significant morbidity and mortality. Entamoeba histolytica is the principle protozoan parasite associated with amoebiasis. Public health efforts should be directed towards its control and better diagnostic methods should be employed for distinguishing between pathogenic and non-pathogenic species of Entamoeba.