Prevalence of cases of amebic liver abscess in a tertiary care centre in India: A study on risk factors, associated microflora and strain variation of Entamoeba histolytica

Epidemiology, risk factors, and clinical characteristics of amoebic liver abscess: a systematic review and meta-analysis from India

Amoebiasis and its extraintestinal manifestation amoebic liver abscess (ALA) is an endemic disease in tropical and subtropical countries. However, no meta-analysis on the prevalence, associated risk factors, and clinical markers has been performed. This study aims to bridge this research gap. Based on our inclusion criteria, 18 studies were selected for analysis. Using the "meta" package in RStudio, forest plots, regression analysis, and funnel plots were used to represent the proportional meta-analysis, significance of the correlation, and quality and publication bias of the included studies, respectively. A high prevalence of ALA (67%, p = 1.762 × 10-15) was noted in cases of liver abscess. ALA was significantly more prevalent in males (86%, p = 2.25 × 10-8), individuals with poor socioeconomic conditions (75%, p = 0.02496), history of alcohol consumption (63%, p = 1.421 × 10-8), and diabetic comorbidity (35%, p = 0.01169). There was a significant correlation with abdominal pain (91%, p = 1.286 × 10-12), infected right lobe (81%, p = 0.002), fever (73%, p = 2.567 × 10-12), hepatomegaly (69%, p = 1.223 × 10-5), anemia (69%, p = 1.223 × 10-5), and jaundice (11%, p = 0005258) in the affected individuals. We conclude that the above-stated risk factors and clinical markers are significantly associated with ALA and suggest that medical professionals in endemic regions must attribute liver abscess to be etiologically amoebic and correlate the disease manifestation with the risk factors and clinical markers. Further, research is needed to better understand disease manifestation.

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.

Paeniclostridium sordellii causing liver abscess: A rare case report in India

Paeniclostridium sordellii, an anaerobic bacterium, causes hepatic infections in alcoholics and post-surgery (liver transplantation). While liver and brain abscesses are rare, drainage procedures and targeted antibiotic therapy assisted by early microbiological diagnosis have reduced mortality rates. We report a rare case of pyogenic liver abscess caused by Paeniclostridium sordellii in India, the early diagnosis of which has led to life saving outcome for the patient. Hence, the microbiological diagnosis and comprehensive medical-surgical treatment are vital for preventing mortality in Paeniclostridium sordellii infections.

Neutrophils versus Protozoan Parasites: Plasmodium, Trichomonas, Leishmania, Trypanosoma, and Entameoba

Neutrophils are the most abundant polymorphonuclear granular leukocytes in human blood and are an essential part of the innate immune system. Neutrophils are efficient cells that eliminate pathogenic bacteria and fungi, but their role in dealing with protozoan parasitic infections remains controversial. At sites of protozoan parasite infections, a large number of infiltrating neutrophils is observed, suggesting that neutrophils are important cells for controlling the infection. Yet, in most cases, there is also a strong inflammatory response that can provoke tissue damage. Diseases like malaria, trichomoniasis, leishmaniasis, Chagas disease, and amoebiasis affect millions of people globally. In this review, we summarize these protozoan diseases and describe the novel view on how neutrophils are involved in protection from these parasites. Also, we present recent evidence that neutrophils play a double role in these infections participating both in control of the parasite and in the pathogenesis of the disease.

Difficult to treat liver abscesses in children - Do not forget parasitic infections

Liver abscess (LA) is a significant health concern worldwide, particularly in tropical regions such as India, and is usually pyogenic or amoebic in origin. In rare cases it can be caused by parasites. We present two children with difficult-to-treat LAs, revealing underlying parasitic infections as the causative agents, implicated by eosinophilia, elevated immunoglobulin-E levels and exposure to domestic animals. In the first case, disseminated echinococcosis was diagnosed through imaging, serology and histopathology. The second case showed a relationship between LAs and Toxocara infection, evidenced by microscopic stool examination of a household cat.

Clinical characteristics, diagnosis, treatment, and outcome of patients with liver abscess due to Aspergillus spp: a systematic review of published cases

BACKGROUND

Aspergillus spp liver abscess is a relatively rare entity and thus far no systematic review has been performed examining patients' demographics, clinical manifestations, diagnosis, management, and outcome.

METHODS

We performed a systematic review of the literature using MEDLINE and LILACS databases. We searched for articles published in the period from January 1990 to December 24, 2022, to identify patients who developed liver abscesses due to Aspergillus spp.

RESULTS

Our search yielded 21 patients all of whom had invasive aspergillosis confirmed on liver biopsy. Of these patients 81% were adults, and 60% were males. The majority (86%) of patients were immunocompromised and 95% had symptomatic disease at the time of diagnosis. The most common symptoms were fever (79%), abdominal pain (47%), and constitutional symptoms (weight loss, chills, night sweats, fatigue) (38%). Liver enzymes were elevated in 50%, serum galactomannan was positive in 57%, and fungal blood cultures were positive in only 11%. Co-infection with other pathogens preceded development of apsergillosis in one-third of patients, and the majority of the abscesses (43%) were cryptogenic. In the remaining patients with known source, 28% of patients developed liver abscess through dissemination from the lungs, 19% through the portal vein system, and in 10% liver abscess developed through contiguous spread. The most common imaging modality was abdominal computerized tomography done in 86% of patients. Solitary abscess was present in 52% of patients while 48% had multiple abscesses. Inadequate initial empiric therapy was prescribed in 60% of patients and in 44% of patients definite treatment included combination therapy with two or more antifungal agents. Percutaneous drainage of the abscesses was done in 40% of patients, while 20% required liver resection for the treatment of the abscess. Overall mortality was very high at 38%.

CONCLUSION

Further studies are urgently needed for a better understanding of pathophysiology of liver aspergillosis and for developement of newer blood markers in order to expedite diagnosis and decrease mortality.

Observational Study of Clinical Profiles and Management of Liver Abscess in Hospitalized Patients: A North Indian Tertiary Care Perspective

Background Liver abscesses are a significant health concern, necessitating prompt diagnosis and appropriate management. Spontaneous liver abscesses are a frequent reason for hospitalizations in India, particularly in the northern part. By analyzing demographics, symptoms, radiological findings, laboratory parameters, and treatment outcomes, this study will contribute valuable insights to enhance the understanding and management of liver abscesses. Aims and objective To evaluate demographic, clinical, laboratory, and radiological parameters and management options in hospitalized patients with liver abscesses at a tertiary care center. Methods This study retrospectively analyzed prospectively collected data from 150 patients diagnosed with liver abscesses who were admitted to our ward for one year. Data on demographic characteristics, clinical presentation, etiology, radiological findings, laboratory investigations, management strategies, and treatment outcomes were collected. Descriptive statistics and relevant statistical tests were employed for data analysis. Results The study population had a mean age of 40.28±12.72 years, with a male preponderance (136 (90.7%)). Amoebic abscesses (94 (62.7%)) were the most common. Hepatomegaly (144 (96%)), fever (140 (93.3%)), abdominal pain (136 (90.7%)), and anorexia (118 (78.7%)) were the most common symptoms. Ultrasonography revealed solitary abscesses (99 (66%)) to be more common than multiple abscesses (24 (16%)), with a predominant location in the right lobe (128 (85.3%)). Laboratory investigations showed leukocytosis in 121 (80.7%), elevated liver enzymes (95 (63.3%) aspartate aminotransferase (AST) and 80 (53.3%) alanine transaminase (ALT)), elevated alkaline phosphatase (ALP) in 133 (88.7%), and low albumin levels (138 (92%)) in a significant proportion of patients. Single-time needle aspiration (95 (63.3%)), percutaneous drain (36 (24%)), and surgical intervention (4 (2.7%)) were the primary treatment modalities. Serum albumin level (p<0.001) and ALP (p<0.001) were significantly low and high, respectively, in patients with hospital stays ≥10 days. Conclusions This study provides insights into patients with liver abscesses' clinical and laboratory parameters and management strategies. The findings highlight the diverse clinical presentation, varied etiologies, and the importance of radiological imaging and laboratory investigations in diagnosis and management. Tailored treatment strategies based on the patient's condition are crucial for optimizing outcomes.

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.

Amebic liver abscess by Entamoeba histolytica

Amebic liver abscesses (ALAs) are the most commonly encountered extraintestinal manifestation of human invasive amebiasis, which results from Entamoeba histolytica (E. histolytica) spreading extraintestinally. Amebiasis can be complicated by liver abscess in 9% of cases, and ALAs led to almost 50000 fatalities worldwide in 2010. Although there have been fewer and fewer cases in the past several years, ALAs remain an important public health problem in endemic areas. E. histolytica causes both amebic colitis and liver abscess by breaching the host's innate defenses and invading the intestinal mucosa. Trophozoites often enter the circulatory system, where they are filtered in the liver and produce abscesses, and develop into severe invasive diseases such as ALAs. The clinical presentation can appear to be colitis, including upper-right abdominal pain accompanied by a fever in ALA cases. Proper diagnosis requires nonspecific liver imaging as well as detecting anti-E. histolytica antibodies; however, these antibodies cannot be used to distinguish between a previous infection and an acute infection. Therefore, diagnostics primarily aim to use PCR or enzyme-linked immunosorbent assay to detect E. histolytica. ALAs can be treated medically, and percutaneous catheter drainage is only necessary in approximately 15% of cases. The indicated treatment is to administer an amebicidal drug (such as tinidazole or metronidazole) and paromomycin or other luminal cysticidal agent for clinical disease. Prognosis is good with almost universal recovery. Establishing which diagnostic methods are most efficacious will necessitate further analysis of similar clinical cases.

Updates on the worldwide burden of amoebiasis: A case series and literature review

BACKGROUND

Amoebiasis is an intestinal and tissue parasitic infection caused by the protozoan Entamoeba histolytica. Despite significant medical importance and worldwide dispersion, little is known about the epidemiology and distinct geographical distribution of various clinical forms of amoebiasis in the world. In this study, we present an amoebiasis case series referred to Avicenne Hospital (Bobigny, France) from 2010 to 2022 followed by an overview of the released literature to explore diverse clinico-pathology of amoebiasis and to update the actual epidemiological situation of this parasitosis worldwide.

METHODS

The referred patients underwent a combination of clinical and parasitological examinations and imaging. The study was followed by an overview of released literature performed based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline.

RESULTS

A total of 15 patients with amoebiasis were diagnosed with an average age of 48.5 years old at the occurrence time of infection. Men (78%) were the most affected patients. Most of the cases were reported following a trip to endemic regions, such as Mali, India, Nepal, Algeria, Cameroon or Congo. All of the processed patients exhibited a hepatic amoebiasis. Amoebic abscess was observed in all cases with an average size of 6.3 cm. Of these patients, seven cases (46.7%) benefited from drainage following a risk of rupture or superinfection of the abscess. A compilation of findings extracted from 390 scientific publications via seven major medical databases, allowed us to update the main epidemiological and clinical events that has led to the current worldwide expansion of amoebiasis. We presented a clinical and epidemiological overview of the amoebiasis accompanied with a worldwide illustrative map displaying the current distribution of known amoebiasis foci in each geographical ecozone of Asia, Europe, Africa, Americas, and Australia.

CONCLUSIONS

Although Metropolitan France is not known as an endemic region of amoebiasis, amoebic liver abscess was the most frequent clinical form observed among our 15 patients processed. Most of infected patients had a history of travel to or lived-in endemic areas before arriving in France.

Gene expression of axenically-isolated clinical Entamoeba histolytica strains and its impact on disease severity of amebiasis

The severity of Entamoeba histolytica infection is determined by host immunology, pathogen virulence, and the intestinal environment. Conventional research for assessing pathogen virulence has been mainly performed using laboratory strains, such as a virulent HM-1: IMSS (HM-1) and an avirulent Rahman, under various artificial environmental conditions because of the difficulties of axenic isolation of the clinical strains. However, it is still unclear whether scientific knowledge based on laboratory strains are universally applicable to the true pathogenesis. Hereby, we performed transcriptomic analysis of clinical strains from patients with different degrees of disease severity, as well as HM-1 under different conditions. Even after several months of axenization, Clinical strains show the distinct profile in gene expression during in vitro passage, moreover, difference between any 2 of these strains was much greater than the changes on the liver challenge. Interestingly, 26 DEGs, which were closely related to the biological functions, were oppositely up- or down regulated between virulent Ax 19 (liver abscess) and avirulent Ax 11 (asymptomatic carrier). Additionally, RNAseq using laboratory strain (HM1) showed more than half of genes were differently expressed between continuously in vitro passaged HM1 (in vitro HM1) and periodically liver passaged HM1 (virulent HM1), which was much greater than the changes on the liver passage of virulent HM1. Also, transcriptomic analysis of a laboratory strain revealed that continuous environmental stress enhances its virulence via a shift in its gene expression profile. Changes in gene expression patterns on liver abscess formation were not consistent between clinical and laboratory strains.

Various genotypes of Entamoeba histolytica are prevalent in the field. Some papers suggest the association between genotypes and disease severity. However, most studies for assessing pathogen virulence were performed using laboratory strains, such as virulent HM1: IMSS (HM1) and avirulent Rahman, because axenic isolation from clinical specimen is technically complex and time consuming. This transcriptomic analysis using clinical strains from the patients with different clinical severity, as well as the laboratory strain HM1 under different conditions showed unique gene expression patterns. Following things were confirmed; 1. Virulent clinical strain maintains its virulence with unique gene expression pattern after axenic isolation, 2. Continuous environmental stress enhances its virulence via the accumulation of altered gene expressions, and 3. Changes in gene expression on the liver abscess formation are not always the same amongst strains. For an accurate understanding the pathogenesis, comprehensive analyses of various clinical strains under different environmental conditions should be promoted.

Amebic liver abscess: Clinico-radiological findings and interventional management

In its classic form, amebic liver abscess (ALA) is a mild disease, which responds dramatically to antibiotics and rarely requires drainage. However, the two other forms of the disease, i.e., acute aggressive and chronic indolent usually require drainage. These forms of ALA are frequently reported in endemic areas. The acute aggressive disease is particularly associated with serious complications, such as ruptures, secondary infections, and biliary communications. Laboratory parameters are deranged, with signs of organ failure often present. This form of disease is also associated with a high mortality rate, and early drainage is often required to control the disease severity. In the chronic form, the disease is characterized by low-grade symptoms, mainly pain in the right upper quadrant. Ultrasound and computed tomography (CT) play an important role not only in the diagnosis but also in the assessment of disease severity and identification of the associated complications. Recently, it has been shown that CT imaging morphology can be classified into three patterns, which seem to correlate with the clinical subtypes. Each pattern depicts its own set of distinctive imaging features. In this review, we briefly outline the clinical and imaging features of the three distinct forms of ALA, and discuss the role of percutaneous drainage in the management of ALA.

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.

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.

Clinical Characteristics of Diabetes Complicated by Bacterial Liver Abscess and Nondiabetes-Associated Liver Abscess

Background. Bacterial liver abscess (BLA) is a secondary infectious disease caused by hepatic parenchymal inflammation and bacterial necrosis. Studies have shown that diabetic patients with BLA have higher rates of related adverse events than patients without diabetes. Aim. To explore the clinical characteristics of BLA complicated with diabetes and nondiabetes-related BLA. Methods. From January 2019 to June 2020, 61 diabetic patients with BLA were included as the study group, and 61 BLA patients without diabetes were included as the control group. Clinical manifestations, laboratory examination index (prothrombin activity (PTA), albumin (propagated), white blood cell count (WBC), red blood cell count (RBC), plasma fibrinogen (FIB), C-reactive protein (CRP), neutrophil percentage (NEUT), and prealbumin (PA)) levels, blood cultivation, and fester situation in the two groups were analyzed. Results. No differences of Fever, right upper abdominal pain, jaundice, vomiting and nausea, liver tenderness, and liver pain upon percussion were observed between the study and control groups. However, chill, cough and expectoration, and liver pain upon percussion were higher in the study group, while abdominal distension was lower. WBC, RBC, PA, PTA, FIB, and CRP were higher than the control group. NEUT was higher in the study group than in the control group and Alb was lower than that in the control group. There was no significant difference between the positivity of blood bacterial culture in the study and control groups. The positivity rate of Klebsiella pneumoniae in Gram-negative aerobic bacteria in the study group was higher than that in the control group. There was no significant difference between the positivity of fester culture of the two groups. The positivity of K. pneumoniae in Gram-negative aerobic bacteria in the study group was higher than that in the control group. The positivity of E. coli was lower in the study group than in the control group. Conclusion. Clinical manifestations and laboratory results of BLA patients with and without diabetes mellitus were significantly different. The symptoms of diabetics with BLA were serious.

Detection of Entamoeba histolytica and bacterial etiological agents in patients with clinically suspected cases of liver abscesses

Liver abscess is one of the conditions having multiple etiological agents. It can be parasitic or can be due to bacterial among other causes. Entamoeba histolytica is one of the common protozoan parasites causing amoebic liver abscess. So, accurate diagnosis is important for proper management and treatment. We have tried to detect the various bacterial etiological agents along with Entamoeba histolytica using culture of bacteria and polymerase chain reaction for E. histolytica in suspected liver abscess cases. Liver aspirates/pus collected from 63 patients were subjected to bacterial gram staining and culture along with wet mount and PCR for E. histolytica. Patients' clinical details and outcomes were also noted and co-related.It was seen that 22 (34.9%) out of 63 samples showed the presence of bacteria by gram staining whereas aerobic bacterial growth was seen in 28.6% and only 1.6% in anaerobic culture. Amoebic liver abscess showed E. histolytica  in 36 patients out of 63 study participants (57.1%) by PCR. The study showed that 44.4% of patients had a habit of alcohol consumption and 19.1% were chronic smokers. Abdominal pain (90.3%) was the most common presenting feature followed by fever (64.5%). The most common co-morbidities in the enrolled patients was diabetes mellitus (19.3%) and least with chronic liver disease (3.2%). Liver abscess, a multi-etiological condition needs a robust diagnostic method. Just a single method or a single sample type is not sufficient to diagnose, as it may miss out other causes. Treating its associated co-morbidities may help to lessen it.

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

BACKGROUND

Entamoeba infections have major impact on millions of the people worldwide. Entamoeba histolytica has long been accepted as the only pathogenic species. However, recent reports of other Entamoeba spp. in symptomatic cases have raised questions on their pathogenicity.

METHODOLOGY/PRINCIPAL FINDINGS

Total 474 stool samples and 125 liver aspirates from patients with intestinal and extra intestinal manifestations and from community were included. Sewage samples from the hospital and the city were also included. Microscopic examination and molecular detection were performed to detect presence of E. histolytica/ dispar/ moshkovskii/ bangladeshi. The associated demographic and socioeconomic factors were statistically analyzed with the presence of Entamoeba. Microscopy detected Entamoeba spp. in 5.4% stool and 6.4% liver aspirate samples. Through nested multiplex PCR, prevalence of Entamoeba spp. in intestinal and extra-intestinal cases was 6.6% (20/301) and 86.4% (108/125) respectively and in asymptomatic population was 10.5% (13/123). Sewage samples did not show presence of any Entamoeba spp. Uneducated subjects, low economic conditions, untreated drinking water, consumption of raw vegetables and habit of not washing hands before meals were significantly associated with presence of Entamoeba spp.

CONCLUSIONS

E. histolytica still remains the only Entamoeba spp. in invasive extra intestinal infections. E. dispar was detected in both asymptomatic and symptomatic intestinal infections. Routine identification of Entamoeba spp. should incorporate PCR based detection methods.

Immune Response to the Enteric Parasite Entamoeba histolytica

Entamoeba histolytica is a protozoan parasite responsible for amoebiasis, a disease with a high prevalence in developing countries. Establishing an amoebic infection involves interplay between pathogenic factors for invasion and tissue damage, and immune responses for protecting the host. Here, we review the pathogenicity of E. histolytica and summarize the latest knowledge on immune response and immune evasion mechanisms during amoebiasis.

Neutrophils vs. amoebas: Immunity against the protozoan parasite Entamoeba histolytica

Entamoeba histolytica is a protozoan parasite with high prevalence in developing countries, and causes amoebiasis. This disease affects the intestine and the liver, and is the third leading cause of human deaths among parasite infections. E. histolytica infection of the intestine or liver is associated with a strong inflammation characterized by a large number of infiltrating neutrophils. Consequently, several reports suggest that neutrophils play a protective role in amoebiasis. However, other reports indicate that amoebas making direct contact with neutrophils provoke lysis of these leukocytes, resulting in the release of their lytic enzymes, which in turn provoke tissue damage. Therefore, the role of neutrophils in this parasitic infection remains controversial. Neutrophils migrate from the circulation to sites of infection, where they display several antimicrobial functions, including phagocytosis, degranulation, and formation of neutrophil extracellular traps (NET). Recently, it was found that E. histolytica trophozoites are capable of inducing NET formation. Neutrophils in touch with amoebas launched NET in an explosive manner around the amoebas and completely covered them in nebulous DNA and cell aggregates where parasites got immobilized and killed. In addition, the phenotype of neutrophils can be modified by the microbiome resulting in protection against amoebas. This review describes the mechanisms of E. histolytica infection and discusses the novel view of how neutrophils are involved in innate immunity defense against amoebiasis. Also, the mechanisms on how the microbiome modulates neutrophil function are described.

Liver Abscess in Children-experience From a Single Tertiary Care Center of North India: Etiology, Clinical Profile and Predictors of Complications

BACKGROUND

Liver abscess (LA), a common problem in children in the tropics, is believed to be mostly pyogenic (PLA), sometimes amebic (ALA). We aimed to analyze the clinical profile, etiology, risk factors for complications, management and outcomes of LA in children.

METHODS

The details of 81 children with LA managed in a tertiary set up over a period of 3 years were analyzed. A comparison of different parameters was performed with respect to etiology and complications.

RESULTS

ALA, PLA and mixed infection LA were diagnosed in 40 (49.4%), 32 (39.5%) and 9 (11.1%) children. The triad of fever, hepatomegaly and right upper quadrant tenderness was seen in 65 (80.2%). Coagulopathy was observed in 60 (77%) and jaundice in 12 (14.8%). Majority (71.6%) had a single LA in the right lobe (69%). Conservative, percutaneous needle aspiration, percutaneous catheter drainage and surgical drainage were done in 11.1%, 3.7%, 82.7% and 2.5%, respectively. Forty-three (53.1%) had complicated LA with rupture in 55.8% and vascular thrombosis in 16.2%. Children with complicated LA had higher alanine transaminase, prolonged prothrombin time/international normalized ratio, low serum protein and albumin levels (P < 0.05). Median duration of follow-up was 2 months and mean time to resolution of LA was 48.5 ± 18 days.

CONCLUSIONS

ALA is the commonest cause of pediatric LA in endemic regions and is difficult to differentiate from PLA clinically. Percutaneous catheter drainage is safe and effective modality for the management of LA in children. A higher alanine transaminase, prolonged prothrombin time/international normalized ratio and low serum albumin levels (<3 g/dL) at presentation identify complicated LA.

Factors Associated with High Rates of Recurrence of Amebic Liver Abscess (ALA) in North India

Recurrence of amebic liver abscess (ALA), once considered unusual, is increasingly being reported, despite proper management. Realizing the endemicity of ALA in the study setup, this 2-year follow-up study was conducted to investigate the recurrent cases and study the associated factors. A total of 101 confirmed cases of ALA were followed up for a period of 2 years. Recurrent cases were studied for associated bacterial flora, presence of resistance genes (nim), level of matrix metalloproteinase 3 and MMP-9, and genotypes of Entamoeba histolytica and statistically compared with the nonrecurrent cases as controls. Recurrence rates of 8.9% (nine patients) were detected. The presence of Prevotella along with an increased level of MMP-9 in abscess fluid and large size of abscesses (11 × 10.8 cm) was found to be significantly associated with recurrence in ALA. Among the nine cases, the presence of nimE gene was detected in two (22.2%) patients. The genotyping of E. histolytica strains showed that in seven (77.7%) cases, the genotype of E. histolytica was the same in the primary and recurrent samples. This study reports a high rate of recurrence in the cases of ALA, hinting toward the gradual development of clinical resistance toward the commonly used drug. The presence of nim gene and Prevotella in abscess fluid along with increased MMP-9 levels and large abscess size could be important predictors of recurrent ALA.

The association between the lack of safe drinking water and sanitation facilities with intestinal Entamoeba spp infection risk: A systematic review and meta-analysis

Intestinal protozoa infections are responsible for considerable morbidity and mortality, especially where the exposed population suffers from a lack of drinking water and sanitation facilities. In this study, the association between the lack of safe drinking water and sanitation (toilet) facilities with intestinal Entamoeba spp infection in the children (5-11 years), adult (18-55 years), and all age (5-55 years) were assessed. For this purpose, some of the international databases such as Scopus, PubMed, Web of Science, and Embase were screened to up to 7 June 2019 in order to retrieve the related citations. Also, the pooled odds ratios (ORs) following 95% confidence intervals (CIs) were calculated using a random-effects model. Twenty-nine articles with 36 studies were included while the OR extracted or calculated by using 2 × 2 contingency tables. However, the ingestion of contaminated water insignificantly can increase the odds ratio (OR) of Entamoeba spp infection (OR 1.01, (95% confidence interval [CI] 0.58 to 1.43), no access to sanitation (toilet) facilities significantly can increase odds of Entamoeba spp infection (OR 1.18, 95% CI 1.05 to 1.32). The meta-regression analysis showed that over time, odds of intestinal Entamoeba spp infection increased in both lack of safe drinking water (Coefficient: 3.24, P-value < 0.01) and sanitation (toilet) facilities (Coefficient: 2.36, P-value < 0.05) subgroups. Considering the findings, lack of safe drinking water resulted in a further increase in intestinal Entamoeba spp infection among adult (OR: 2.76), children (OR = 0.57) and all age groups (OR: 1.50), and also lack of sanitation (toilet) facilities resulted in further increase intestinal Entamoeba spp infection in children (OR: 1.06), adult (OR: 1.26) and all age (OR: 1.16). In this context, the lack of safe drinking water and sanitation facilities (toilet) was associated with a high risk of intestinal Entamoeba spp infection. Further attempts to providing public health facilities can control the prevalence of intestinal Entamoeba spp.

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

Entamoeba histolytica (E. histolytica) is a facultative protozoan parasite implicated in amoebic liver abscesses (ALA), the most common extraintestinal manifestation of this infection. E. histolytica is endemic to sub-tropical and tropical countries and has been a major public health concern in northern Sri Lanka (SLK) for the last three decades. This has been attributed to a multitude of factors such as poor sanitation, hygiene, male sex, middle age, overcrowding, unsanitary practices in the production of indigenous alcoholic beverages, and alcohol consumption. Additionally, while rates of E. histolytica have declined substantially throughout the rest of the island, largely due to better infrastructure, it remains pervasive in the northern peninsula, which is generally less developed. Infection arises primarily from fecal-oral transmission through the consumption of contaminated drinking water containing cysts. Upon ingestion, cysts multiply into trophozoites and colonize the host colonic mucosa using lectin and cysteine proteases as virulence factors, leading to host invasion. Symptoms occur along a spectrum, from asymptomatology, to pyrexia, abdominal cramping, and amoebic dysentery. Colonization of the colon results in the formation of distinct flask-shaped ulcers along the epithelium, and eventual penetration of the lamina propria via the production of matrix metalloproteinases. ALA then develops through trophozoite migration via the mesenteric hepatic portal circulation, where microabscesses coalesce to form a single, large right-lobe abscess, commonly on the posterior aspect. The progression of infection to invasive disease is contingent on the unique interplay between host and pathogen factors, such as the strength of host-immunity to overcome infection and inherent pathogenicity of the Entamoeba species. As a preventable illness, E. histolytica complications such as ALA impose a significant burden on the healthcare system. This mini-review highlights epidemiological trends, risk factors, diagnostic modalities, treatment approaches, and opportunities for prevention of E. histolytica-induced ALA, to help address this endemic problem on the island of SLK.

Pyogenic liver abscess: Clinical features and microbiological profiles in tertiary care center

Background:

Pyogenic liver abscess (PLA) is the end result of a number of pathologic processes that cause a suppurative infection of the liver parenchyma.

Materials and Methods:

Sixty-five patients of age more than 18 years and radiologically confirmed cases of liver abscess were included in this study. Pus and blood samples were collected. Pus was processed for microscopy of trophozoite of Entamoeba histolytica and aerobic and anaerobic bacterial culture. Blood was processed for antibody ELISA for Entamoeba histolytica and aerobic bacterial culture. Identification of aerobic and anaerobic isolates was done by Vitek2 and antibiotic sensitivity test for aerobic bacterial isolates was done by Vitek2.

Result:

Out of sixty five, twenty five were confirmed as PLA. All patients were male with mean age 37.9 years. Fever and upper abdominal pain were the most common symptoms. Right lobe comprised 80% of the abscess. Pus sample was more sensitive than blood sample for diagnosis. There were a total of 33 isolates in our study. Klebsiella pneumoniae (6/33) was the most common aerobic isolate and Clostridium spp. (7/33) was the anaerobic isolate. All gram-negative bacteria were showing good sensitivity for 3^rd and 4^th generation cephalosporins, fluoroquinolones, amikacin, gentamicin, piperacillin-tazobactam, imipenem and meropenem. Abscess >5 cm was treated with percutaneous drainage while abscess <5 cm was treated with antibiotics only.

Conclusion:

Diagnosis should be made with the combination of clinical suspicion, radiology, and microbiology. Empirical therapy should include anaerobic coverage too. Only antibiotic therapy can be given under consideration of size of abscess, persistence of fever after giving antibiotics, and any suspected complications.