Detection and differentiation of Entamoeba histolytica and Entamoeba dispar in clinical samples through PCR-denaturing gradient gel electrophoresis

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.

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.

Diagnosis of Balamuthia mandrillaris Encephalitis by Thymine-Adenine Cloning Using Universal Eukaryotic Primers

Background

Identifying the causal pathogen of encephalitis remains a clinical challenge. A 50-year-old man without a history of neurological disease was referred to our department for the evaluation of an intracranial lesion observed on brain magnetic resonance imaging (MRI) scans, and the pathology results suggested protozoal infection. We identified the species responsible for encephalitis using thymine–adenine (TA) cloning, suitable for routine clinical practice.

Methods

We extracted DNA from a paraffin-embedded brain biopsy sample and performed TA cloning using two universal eukaryotic primers targeting the V4-5 and V9 regions of the 18S rRNA gene. The recombinant plasmids were extracted, and the inserted amplicons were identified by Sanger sequencing and a homology search of sequences in the National Center for Biotechnology Information Basic Local Alignment Search Tool.

Results

The infection was confirmed to be caused by the free-living amoeba Balamuthia mandrillaris. Two of 41 colonies recombinant with 18S V4-5 primers and 35 of 63 colonies recombinant with the 18S V9 primer contained B. mandrillaris genes; all other colonies contained human genes. Pathogen-specific PCR ruled out Entamoeba histolytica, Naegleria fowleri, Acanthamoeba spp., and Toxoplasma gondii infections.

Conclusions

This is the first report of B. mandrillaris-induced encephalitis in Korea based on molecular identification. TA cloning with the 18S rRNA gene is a feasible and affordable diagnostic tool for the detection of infectious agents of unknown etiology.

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.

The epidemiology of amoebiasis in Thi-Qar Province, Iraq (2015-2020): differentiation of Entamoeba histolytica and Entamoeba dispar using nested and real-time polymerase chain reaction

OBJECTIVES

The objective of this study was to evaluate the present status of amoebiasis in Thi-Qar Province in southern Iraq, and to determine the presence of Entamoeba histolytica and Entamoeba dispar with nested and real-time polymerase chain reaction (PCR).

METHODS

Epidemiological data were obtained from the public health department of the Thi-Qar Health Office (2015-2020). Eighty stool samples were also randomly collected from patients ≤12 year of age with diarrhea at 2 hospitals between the beginning of February 2020 and the end of October 2020. These samples were selected after microscopy to identify the 18S rRNA gene in Entamoeba DNA.

RESULTS

Of the 341,554 cases of intestinal parasitic infections, 38,004 (11.1%) individuals were recorded as having amoebiasis, which accounted for the highest proportion of infections in 2015 (26.1%) and the lowest in 2020 (8.1%). Amoebiasis was distributed among all age groups, with the age group of 5-14 years accounting for the highest proportion (27.3%). In molecular testing, 42 (52.5%) out of 80 samples were positive for the 18S rRNA gene (888 bp). Using nested PCR, E. histolytica (439 bp) was detected in 25 (31.3%) samples and E. dispar (174 bp) in 14 (17.5%), while using real-time PCR, E. histolytica and E. dispar were detected in 28 (35.0%) and 15 (18.8%) samples, respectively.

CONCLUSIONS

Epidemiological data confirmed that amoebiasis is endemic in this province, and is not limited to certain months. Our study confirms the applicability of molecular identification to detect pathogenic and non-pathogenic Entamoeba to prescribe the appropriate drug.

The Frequency of the Intestinal Parasites Giardia Lamblia and Entamoeba Histolytica in Pediatric Diarrhea Specimens from Central Iran

Introduction:

Intestinal parasitic infections, particularly those caused by Giardia lamblia, are among the major health problems that exist worldwide, especially in developing countries. This study aimed to investigate the prevalence of the intestinal parasites Giardia lamblia and Entamoeba histolytica that were isolated from samples of infectious diarrhea in pediatric patients from Central Iran.

Methods:

This descriptive cross-sectional study included 230 samples of infectious diarrhea that were collected from May 2015 to February 2016. Direct observation, the formalin-ether sedimentation method and the technique using the Polymerase Chain Reaction (PCR) of β-giardin and EH primers were used for the identification of Giardia lamblia and Entamoeba histolytica.

Results:

Out of 230 samples of infectious diarrhea, five cases (2.1%) of Giardia lamblia and no cases (0%) of Entamoeba histolytica were identified using the formalin-ether sedimentation method and the same result were obtained using PCR technique. Of the five patients who had Giardia lamblia, three (60%) were male and two (40%) were female. The most common clinical symptoms in these patients were stomach ache and diarrhea (100%) and mucus in the stool (80%).

Conclusion:

Giardia lamblia was introduced as a parasitic agent causing diarrhea from Central Iran. The results indicate that pediatricians and, even more importantly, experts in laboratories should pay special attention to the identification of this parasite to treat the patients as effectively and as quickly as possible.

"CLUPS": A New Culture Medium for the Axenic Growth of Entamoeba histolytica

Amebiasis remains a major health problem in Mexico. Therefore, the search for better culture media and low-cost diagnostic and therapeutic tools is fundamental. We present a new culture medium for Entamoeba histolytica which allows the microbe to preserve its virulence factors and ability to induce hepatic abscesses in animal models. The novel CLUPS medium is an improved version of the PEHPS medium, previously designed in our laboratory. The main difference is the substitution of raw beef liver in PEHPS by raw beef lung in the CLUPS medium. To compare the performance of three-culture media (traditional TYI-S-33, PEHPS, and CLUPS), E. histolytica trophozoites were cultured in quintuplicate, followed by the evaluation of phospholipase activity and the induction of liver abscesses in golden hamsters. E. histolytica trophozoites grew significantly better in CLUPS medium than in TYI-S-33. Likewise, CLUPS-cultured trophozoites produced significantly more phospholipases than TYI-S-33-cultured trophozoites. Finally, trophozoites grown in any of the three tested media had similar potential to induce liver abscesses.