Entamoeba histolytica and amoebic liver abscess in northern Sri Lanka: a public health problem

Evaluation of Molecular Assays for Diagnosis of Amoebic Liver Abscess in India with Bayesian Latent Class Analysis

Amoebic liver abscess (ALA) is the most common extra-intestinal complication of Entamoeba histolytica, accounting for 50,000 deaths annually, and is endemic in South Asia. Diagnosis based on microscopic examination is insensitive, and serological assays are not discerning of current infections in endemic settings with high exposure. For a rapid and confirmatory laboratory diagnosis of ALA, the performance of a polymerase chain reaction (PCR), quantitative real time PCR (qPCR), digital droplet PCR (ddPCR), and a loop-mediated isothermal amplification (LAMP) assay that detects E. histolytica DNA in liver abscess pus, and a lectin antigen detection ELISA were evaluated against clinical diagnosis (based on predefined criteria) as the gold standard. Owing to the lack of a laboratory gold standard, a Bayesian latent class analysis approach was also used to determine sensitivity and specificity of these assays. In the latent class analysis, qPCR and ddPCR showed the highest sensitivity (98% and 98.1%) and specificity (both 96.6%), and although clinical diagnosis had a comparable sensitivity to qPCR and ddPCR (95.2%), poorer specificity (64.3%) was seen. Kappa agreement analysis showed that qPCR and ddPCR had a perfect agreement of 1 followed by an agreement of 0.76 (95% CI: 0.64-0.88) with PCR. Considering the performance characteristics and relative ease of setting up qPCR as well as the wide availability of qPCR equipment needed, this would be the most optimal assay for rapid, confirmatory, molecular diagnosis of ALA in the tertiary care laboratory setting in India, whereas further optimization of LAMP or antibody-based detection is required for use at smaller or secondary hospitals.

The role of Nrf2 signaling in parasitic diseases and its therapeutic potential

In response to invading parasites, one of the principal arms of innate immunity is oxidative stress, caused by reactive oxygen species (ROS). However, oxidative stresses play dual functions in the disease, whereby free radicals promote pathogen removal, but they can also trigger inflammation, resulting in tissue injuries. A growing body of evidence has strongly supported the notion that nuclear factor erythroid 2-related factor 2 (NRF) signaling is one of the main antioxidant pathways to combat this oxidative burst against parasites. Given the important role of NRF2 in oxidative stress, in this review, we investigate the activation mechanism of the NRF2 antioxidant pathway in different parasitic diseases, such as malaria, leishmaniasis, trypanosomiasis, toxoplasmosis, schistosomiasis, entamoebiasis, and trichinosis.

Clinical management, pathogen spectrum and outcomes in patients with pyogenic liver abscess in a German tertiary-care hospital

Pyogenic liver abscesses (PLA) are life-threatening disorders and require immediate treatment, but structured evidence is sparse and treatment guidelines are not established. In a retrospective observational study of 221 adult PLA patients (mean age 63 years, 63% men) treated between 2013 and 2019 at the Leipzig University Medical Center, we characterized pathogen spectrum, clinical management and outcomes. Biliary malignancies (33%), cholelithiasis (23%) and ischemic biliary tract disease (16%) were most common causes of PLA. Comorbidities included malignancies (40%) and diabetes mellitus (35%). Abdominal ultrasound was the preferred initial imaging modality (58%). Enterobacterales (58%), enterococci (42%) and streptococci (18%) were identified as most frequent pathogens. 97% of patients were treated with antibiotics and 75% of patients underwent an invasive treatment procedure. The 30-day mortality was almost identical in patients with and without underlying malignancy (14.6% vs. 14.4%, p = 0.96), while the one-year outcome differed significantly (58.4% vs. 29.6%, p < 0.001). Positive blood cultures (OR 4.78, 95% CI 1.39 to 22.5, p = 0.023) and detection of Enterobacterales (OR 3.55, 95% CI 1.40 to 9.97, p = 0.010) were associated with increased 30-day-mortality. We conclude that ultrasound, extensive microbiologic diagnosis, adequate anti-infective therapy and early intervention are crucial for the management of PLA.

Novel diagnostic approach for amoebic liver abscess using cell free (cf) DNA: a prospective study

BACKGROUND

Amoebic liver abscess (ALA) is commonly seen in tropical countries and diagnosis of ALA relies mainly on non-specific serological and imaging techniques as well as PCR from pus.

OBJECTIVE

This study evaluated the potential of using cell free DNA (cfDNA) from serum and urine for diagnosing ALA.

METHODS

We prospectively evaluated quantitative PCR (qPCR) for detection of cf DNA in serum and urine sample in all liver abscess patients. The samples were collected from patients reporting to emergency ward of Postgraduate Institute of Medical Education and Research, Chandigarh, India with symptoms suggestive of liver abscess. Real time PCR was done to detect cf DNA in serum and urine by targeting 99-bp unit of small subunit rRNA of Entamoeba histolytica and conventional PCR for pus.

RESULTS

A total 113 samples (serum and urine) and 100 pus samples were analysed. A total of 62 ALA patients were confirmed; with maximum 57 patients detected by qPCR for cfDNA in the serum, 55 patients by PCR on pus aspirate and 50 ALA patients by qPCR for cfDNA in urine sample. Therefore, the sensitivity of qPCR for detection of cf DNA in serum was 91.94% and for urine was 80.65%.

CONCLUSION

A total of 11.2% of ALA patients were diagnosed only through detection of E. histolytica cf DNA in their serum and urine. Detection of cfDNA from serum, urine of ALA has a potential role in future especially for developing countries as it is a rapid, sensitive and patient friendly diagnostic approach.

Genetic and immune determinants of E. coli liver abscess formation

Systemic infections can yield distinct outcomes in different tissues. In mice, intravenous inoculation of Escherichia coli leads to bacterial replication within liver abscesses, while other organs such as the spleen clear the pathogen. Abscesses are macroscopic necrotic regions that comprise the vast majority of the bacterial burden in the animal, yet little is known about the processes underlying their formation. Here, we characterize E. coli liver abscesses and identify host determinants of abscess susceptibility. Spatial transcriptomics revealed that liver abscesses are associated with heterogenous immune cell clusters comprised of macrophages, neutrophils, dendritic cells, innate lymphoid cells, and T-cells that surround necrotic regions of the liver. Abscess susceptibility is heightened in the C57BL lineage, particularly in C57BL/6N females. Backcross analyses demonstrated that abscess susceptibility is a polygenic trait inherited in a sex-dependent manner without direct linkage to sex chromosomes. As early as 1 d post infection, the magnitude of E. coli replication in the liver distinguishes abscess-susceptible and abscess-resistant strains of mice, suggesting that the immune pathways that regulate abscess formation are induced within hours. We characterized the early hepatic response with single-cell RNA sequencing and found that mice with reduced activation of early inflammatory responses, such as those lacking the LPS receptor TLR4 (Toll-like receptor 4), are resistant to abscess formation. Experiments with barcoded E. coli revealed that TLR4 mediates a tradeoff between abscess formation and bacterial clearance. Together, our findings define hallmarks of E. coli liver abscess formation and suggest that hyperactivation of the hepatic innate immune response drives liver abscess susceptibility.

Effectiveness of a health education program on mothers' knowledge and practice regarding amebiasis

This study was conducted to assess the effectiveness of a health education program on mothers' knowledge and practices related to amebiasis. Pre- and post-I and II-tests were used, along with a two-group quasi-experimental design. The study included a convenience sample of 120 mothers, including 60 from the study and 60 from the control group. Out of the entire number of PHCs in Wasit Governorate, seven were used for the study. A three-part structured questionnaire tests mothers' knowledge of the illness and attitudes about it. The results of this study indicated that there is statistically significant difference between the study and control groups during the post-test I and post-test II periods (t=14.968, P=.000 and t=13.731, P=.000, respectively). Data from the study group during the pre-test period of 31.17(9.14) revealed that (70%) of mothers had bad practices connected to Entameba Histolytica among children. According to the post-test I results, 47.4 (9.48) respondents, or 70%, identified good practices. The main finding showed that, after the educational program was implemented, mothers' knowledge and practice of amebiasis dramatically increased, with pre-post implementation differences that are statistically significant.

Amoebiasis: Advances in Diagnosis, Treatment, Immunology Features and the Interaction with the Intestinal Ecosystem

This review of human amoebiasis is based on the most current knowledge of pathogenesis, diagnosis, treatment, and Entamoeba/microbiota interactions. The most relevant findings during this last decade about the Entamoeba parasite and the disease are related to the possibility of culturing trophozoites of different isolates from infected individuals that allowed the characterization of the multiple pathogenic mechanisms of the parasite and the understanding of the host-parasite relationship in the human. Second, the considerable advances in molecular biology and genetics help us to analyze the genome of Entamoeba, their genetic diversity, and the association of specific genotypes with the different amoebic forms of human amoebiasis. Based on this knowledge, culture and/or molecular diagnostic strategies are now available to determine the Entamoeba species and genotype responsible for invasive intestinal or extraintestinal amoebiasis cases. Likewise, the extensive knowledge of the immune response in amoebiasis with the appearance of new technologies made it possible to design diagnostic tools now available worldwide. Finally, the understanding of the interaction between the Entamoeba species and the intestinal microbiota aids the understanding of the ecology of this parasite in the human environment. These relevant findings will be discussed in this review.

Genetic and immune determinants of E. coli liver abscess formation

Systemic infections can yield distinct outcomes in different tissues. In mice, intravenous inoculation of E. coli leads to bacterial replication within liver abscesses while other organs such as the spleen largely clear the pathogen. Abscesses are macroscopic necrotic regions that comprise the vast majority of the bacterial burden in the animal, yet little is known about the processes underlying their formation. Here, we characterize E. coli liver abscesses and identify host determinants of abscess susceptibility. Spatial transcriptomics revealed that liver abscesses are associated with heterogenous immune cell clusters comprised of macrophages, neutrophils, dendritic cells, innate lymphoid cells, and T-cells that surround necrotic regions of the liver. Susceptibility to liver abscesses is heightened in the C57BL/6 lineage, particularly in C57BL/6N females. Backcross analyses demonstrated that abscess susceptibility is a polygenic trait inherited in a sex-dependent manner without direct linkage to sex chromosomes. As early as one day post infection, the magnitude of E. coli replication in the liver distinguishes abscess-susceptible and abscess-resistant strains of mice, suggesting that the immune pathways that regulate abscess formation are induced within hours. We characterized the early hepatic response with single-cell RNA sequencing and found that mice with reduced activation of early inflammatory responses, such as those lacking the LPS receptor TLR4, are resistant to abscess formation. Experiments with barcoded E. coli revealed that TLR4 mediates a tradeoff between abscess formation and bacterial clearance. Together, our findings define hallmarks of E. coli liver abscess formation and suggest that hyperactivation of the hepatic innate immune response drives liver abscess susceptibility.

Natural marine products as antiprotozoal agents against amitochondrial parasites

The goal of this work is to compile and discuss molecules of marine origin reported in the scientific literature with anti-parasitic activity against Trichomonas, Giardia, and Entamoeba, parasites responsible for diseases that are major global health problems, and Microsporidial parasites as an emerging problem. The presented data correspond to metabolites with anti-parasitic activity in human beings that have been isolated by chromatographic techniques from marine sources and structurally elucidated by spectroscopic and spectrometric procedures. We also highlight some semi-synthetic derivatives that have been successful in enhancing the activity of original compounds. The biological oceanic reservoir offers the possibility to discover new biologically active molecules as lead compounds to develop new drug candidates. The molecular variety is extensive and must be correctly explored and managed. Also, it will be necessary to take some actions to preserve the source species from extinction or overharvest (e.g., by cryopreservation of coral spermatozoa, oocytes, embryos, and larvae) and coordinate appropriate exploitation to increase the chemical knowledge of the natural products generated in the oceans. Additional initiatives such as the total synthesis of complex natural products and their derivatives can help to prevent overharvest of the marine ecosystems and at the same time contribute to the discovery of new molecules.

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Natural active components of marine organisms have specific biological properties.

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The marine compounds have multiple anti-parasitic activity.

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The semi-synthetic derivatives of natural active components of marine organism are candidates for new drugs.

Clinical and laboratory profile of patients with amoebic liver abscess

Context

Amebic liver abscess (ALA) occurs in 3%-9% of the amebiasis cases, with complications seen in 20%-40% of the cases and 2%-18% mortality rate. Successful treatment thus requires the accurate identification of these cases.

Aims and Objectives

We aimed to assess the seropositivity and profile of ALA patients in western Rajasthan.

Materials and Methods

This retrospective study was conducted at a tertiary care center in western Rajasthan from November 2017 to May 2019. Serological diagnosis of ALA was done by detecting immunoglobulin G (IgG) antibodies in the serum of the patients by ELISA. The derangements in laboratory profile (hematological and biochemical parameters) and ultrasonography findings were assessed from the hospital records. Statistical analysis was performed using Mann-Whitney U-test.

Results

Among the total cases (n = 34), 20 were diagnosed as ALA. Twenty-one (61.8%) were positive for anti-amebic IgG antibodies. Among ALA patients, 14 (70%) were >40 years old and only 6 (30%) patients were of age ≤40 years. Male: female ratio was 5.7:1, and ultrasonography records of 15 ALA patients revealed the presence of hepatomegaly (n = 7, 46.7%), pleural effusion (n = 3, 20%), lung collapse (n = 2, 13.3%), and vascular involvement (n = 1, 6.7%). The right lobe of the liver was involved in majority of the patients (n = 12, 80%). Total white blood cell count (P < 0.001), absolute neutrophil count (P = 0.001), total serum bilirubin (P = 0.019), and serum alkaline phosphatase (P = 0.018) were significantly elevated in ALA patients.

Conclusions

Seroprevalence shows that ALA still remains the dominant etiology in liver abscess patients in this region. There are significant derangements in the laboratory profile that require a larger study for corroboration.

A Case Of Entamoeba Histolytica Infection Among Men Who Have Sex With Men

Entamoeba histolytica is a parasite responsible for intestinal amebiasis and possible extraintestinal manifestations, such as liver abscesses. India, Africa, Mexico, and Central and South America have some of the highest rates of infection due to poor socioeconomic and environmental conditions. The infection has become more common in the United States due to an increase in emigration. There has been a rising incidence of sexual transmission of the infection, most commonly seen in men who have sex with men. Here, we present a case of a symptomatic extraintestinal E histolytica infection in a young Hispanic bisexual man.

A Comparative Analysis of Microscopy, Coproantigen Serology, and Nested Multiplex PCR in the Laboratory Diagnosis of Entamoeba histolytica Infection

Objectives  Amoebiasis is caused by the most common intestinal protozoan parasite Entamoeba histolytica . This parasite causes amoebic colitis, which is manifested by diarrhea, followed by dysentery. The laboratory diagnosis of intestinal amoebiasis in most cases is by microscopic examination of stool samples. Other nonroutine methods include coproantigen enzyme-linked immunosorbent assay (ELISA) from stool samples, serum ELISA for antibodies, stool culture, isoenzyme analysis, and polymerase chain reaction (PCR). The present study aimed to comparatively analyze the different diagnostic modalities used for the detection of E. histolytica from the stool sample of patients with intestinal amoebiasis.

Materials and Methods  This study was undertaken with 631 patients, during a period of 3 years, from January 2017 to December 2019. Stool specimen obtained from each patient was subjected to direct microscopic wet mount examination, coproantigen ELISA, and nested multiplex PCR, respectively.

Results  Out of all the patients tested, 5.2% were positive for E. histolytica. Among the positive cases, stool microscopy was positive in 3.17%, coproantigen ELISA was positive in 29 (4.6%) cases, and PCR was positive in 30 (4.75%) cases.

Statistical Analysis  The prevalence of E. histolytica infection was summarized as percentages. The three diagnostic tests done were statistically analyzed, taking microscopy as the gold standard. The agreement between techniques (microscopy, coproantigen ELISA, and PCR) was analyzed with kappa statistics. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were summarized as percentage with 95% confidence interval.

Conclusion  In all suspected amoebiasis cases, a combination of stool microscopy, coproantigen testing with molecular detection of the parasite offers the best approach to diagnosis of this parasitic infection.

Utility of loop-mediated isothermal amplification as a point-of-care test in diagnosis of amoebic liver abscess

Definitive diagnosis of amoebic liver abscess is challenging owing to the unavailability of sensitive commercial point-of-care molecular tests. The primary aim of our prospective diagnostic study was to compare available laboratory methods for the diagnosis of Entamoeba histolytica in clinical samples with loop-mediated isothermal amplification. We compared deoxyribonucleic acid (DNA) analysis methods, namely, loop-mediated isothermal amplification and reverse transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA) using pus, stool and blood samples from 200 patients with clinical and radiological diagnosis of amoebic liver abscess. Loop-mediated isothermal amplification had significantly higher sensitivity (88%) as compared to reverse transcriptase polymerase chain reaction (64%) and excellent specificity (100%).

Virtual Screening of FDA-Approved Drugs against Triose Phosphate Isomerase from Entamoeba histolytica and Giardia lamblia Identifies Inhibitors of Their Trophozoite Growth Phase

Infectious diseases caused by intestinal protozoan, such as Entamoeba histolytica (E. histolytica) and Giardia lamblia (G. lamblia) are a worldwide public health issue. They affect more than 70 million people every year. They colonize intestines causing primarily diarrhea; nevertheless, these infections can lead to more serious complications. The treatment of choice, metronidazole, is in doubt due to adverse effects and resistance. Therefore, there is a need for new compounds against these parasites. In this work, a structure-based virtual screening of FDA-approved drugs was performed to identify compounds with antiprotozoal activity. The glycolytic enzyme triosephosphate isomerase, present in both E. histolytica and G. lamblia, was used as the drug target. The compounds with the best average docking score on both structures were selected for the in vitro evaluation. Three compounds, chlorhexidine, tolcapone, and imatinib, were capable of inhibit growth on G. lamblia trophozoites (0.05–4.935 μg/mL), while folic acid showed activity against E. histolytica (0.186 μg/mL) and G. lamblia (5.342 μg/mL).

Machine learning model for predicting malaria using clinical information

BACKGROUND

Rapid diagnosing is crucial for controlling malaria. Various studies have aimed at developing machine learning models to diagnose malaria using blood smear images; however, this approach has many limitations. This study developed a machine learning model for malaria diagnosis using patient information.

METHODS

To construct datasets, we extracted patient information from the PubMed abstracts from 1956 to 2019. We used two datasets: a solely parasitic disease dataset and total dataset by adding information about other diseases. We compared six machine learning models: support vector machine, random forest (RF), multilayered perceptron, AdaBoost, gradient boosting (GB), and CatBoost. In addition, a synthetic minority oversampling technique (SMOTE) was employed to address the data imbalance problem.

RESULTS

Concerning the solely parasitic disease dataset, RF was found to be the best model regardless of using SMOTE. Concerning the total dataset, GB was found to be the best. However, after applying SMOTE, RF performed the best. Considering the imbalanced data, nationality was found to be the most important feature in malaria prediction. In case of the balanced data with SMOTE, the most important feature was symptom.

CONCLUSIONS

The results demonstrated that machine learning techniques can be successfully applied to predict malaria using patient information.

Acute fulminant necrotizing amebic colitis in a pediatric patient: a rare complication of amebiasis with high mortality-a case report

Background

The majority of amebic infections among humans remain asymptomatic. Rarely, the disease takes a fulminant acute course due to the development of necrotizing amebic colitis. This complication is usually found in adult patients. However, on the contrary, this case was diagnosed in a 9-year-old patient. He was transferred to the Sirimavo Bandaranayake Specialized Children’s Hospital (SBSCH), Peradeniya from the District General Hospital, Kilinochchi. To our knowledge, this is the first report of this rare complication in a child in Sri Lanka.

Case presentation

We present a case of acute fulminant necrotizing amebic colitis in a 9-year-old boy. Surgical exploration revealed extensive ulceration and multiple perforations in the entire colon. PAS-Martius Yellow 40 stain highlighted amebae with erythrophagocytosis within the necrotic debris of the ulcers. The polymerase chain reaction (PCR) that was conducted to confirm the diagnosis was positive for Entameba histolytica. The post-operative course was marked with antimicrobial treatment for septicemia and the need for ventilator assistance. Antimicrobial treatment included intravenous metronidazole. The patient progressively recovered and was discharged on a normal diet.

Conclusion

This case reports an acute fulminant necrotizing amebic colitis in a 9-year-old patient. After the treatments, the patient progressively recovered and was discharged on a normal diet. E. histolytica infections in northern Sri Lanka should be given attention as a public health concern. Furthermore, this case highlights that acute fulminant amebic colitis requires early surgical intervention, aggressive supportive and anti-amebic treatments. Clinicians should be cognizant of this potentially fatal complication of amebic colitis.