[Non-pathogenic intestinal amoebae: a clinical-analytical overview]

Navigating the complex relationship between human gut microbiota and breast cancer: Physiopathological, prognostic and therapeutic implications

The human body represents the habitat of trillions of symbiotic microorganisms, collectively known as human microbiota, approximately half of which residing in the gut. The development of next-generation sequencing techniques has boosted the profiling of human microbiota in recent years. A growing body of evidence seems to support a strict relationship between the disruption of the mutualistic relationship between the microbiota and the host (i.e., dysbiosis) and the development of several diseases, including breast malignancies. Breast cancer still represents the most frequent cause of cancer-related death in women. Its complex relationship with gut microbiota is the object of a growing body of evidence. In fact, the interaction with the host immune system and a direct impact of gut microbiota on estrogen, lipid and polyphenols metabolism, seem to potentially affect breast tumor development, progression and response to treatments. In this review, in an attempt to help oncologists navigating this rapidly-evolving research field, we provide an essential overview on the taxonomy, main analytical techniques and terminology most commonly adopted. We discuss what is currently known regarding the interaction between gut microbiota and breast cancer and potential efforts to harness this complex interplay for therapeutic purposes, and revise main ongoing studies. We also briefly provide an overview on breast cancer intratumoral microbiota and its potential role beyond gut microbiota.

Clinical features of amoebic appendicitis in children: A study of 23 cases

AIM OF THE STUDY

To describe the clinical, surgical, and pathological features of children with acute appendicitis and amebiasis.

MATERIALS AND METHODS

The medical records of children diagnosed with appendicitis and amebiasis treated at Fundación Hospital la Misericordia were retrospectively reviewed. Patients were classified into two groups according to the location of the amoebas: the amoebic appendicitis (AA) group (when the amoebic infection involved the appendiceal wall), and the appendicitis with incidental amoebiasis (IA) group (when amoebas were only found in the appendiceal lumen). We compared demographics and outcomes.

RESULTS

We identified 23 children with appendicitis and amoebiasis. The mean age was 9 (3-15) years, and 52% were male. The main duration of the pain at the time of presentation was 1.8 (1-4) days. Fever and diarrhea were observed in 64% and 43% of the patients, respectively. Four patients had perforated appendicitis, all of them within the AA group. Anti-parasitic therapy was used only in 2 subjects (all other patients were diagnosed after discharge and were asymptomatic on follow up). AA was diagnosed in 11 patients and IA in 12. AA and IA patients shared similar characteristics regarding age, clinical findings, radiologic features, and preoperative laboratory results. Appendiceal necrosis and perforation were only found within the AA group (4 patients).

CONCLUSIONS

AA is a rare condition in children. It seems to have a greater risk of perforation than cases of appendicitis with IA, which is in agreement with the more severe histological findings in our series. Anti-parasitic treatment is not necessary in cases of AA or IA.

Diseases Caused by Amoebae in Fish: An Overview

Parasitic and amphizoic amoebae are ubiquitous and can affect a huge variety of hosts, from invertebrates to humans, and fish are not an exception. Most of the relationships between amoebae and fish are based on four different types: ectocommensals, ectoparasites, endocommensals and endoparasites, although the lines between them are not always clear. As ectocommensals, they are located specially on the gills and particularly the amphizoic Neoparamoeba perurans is the most relevant species, being a real pathogenic parasite in farmed salmon. It causes amoebic gill disease, which causes a progressive hyperplasia of epithelial cells in the gill filaments and lamellae. Nodular gill disease is its analogue in freshwater fish but the causative agent is still not clear, although several amoebae have been identified associated to the lesions. Other species have been described in different fish species, affecting not only gills but also other organs, even internal ones. In some cases, species of the genera Naegleria or Acanthamoeba, which also contain pathogenic species affecting humans, are usually described affecting freshwater fish species. As endocommensals, Entamoebae species have been described in the digestive tract of freshwater and marine fish species, but Endolimax nana can reach other organs and cause systemic infections in farmed Solea senegalensis. Other systemic infections caused by amoebae are usually described in wild fish, although in most cases these are isolated cases without clinical signs or significance.

Contrasting microbiota profiles observed in children carrying either Blastocystis spp. or the commensal amoebas Entamoeba coli or Endolimax nana

Recent studies have shown how intestinal parasites can modulate gut microbiota. This observation is not surprising since the human intestinal lumen, like any other niche, is a battlefield of microbial competition, and Eukaryotes can affect bacterial populations. Intestinal pathogenic protist has been associated with reshaping the microbial community structure; however, the interactions between the colonic bacterial communities and parasites like Blastocystis spp., Entamoeba coli, and Endolimax nana have been poorly studied. In this work, we studied the distal intestinal bacterial microbiota of 49 children attending 7 public daycare centers in Medellin, Colombia, and compared the bacterial microbiota structure in the presence or absence of the protists Blastocystis spp., E. coli, and E. nana. Parasite colonization was associated with an increase in bacterial richness. Moreover, Blastocystis spp. presented a positive relationship with Prevotella, since this bacterium was selectively enriched in children carrying it. Remarkably, the E. coli colonized children showed a microbial profile that was closer to uninfected controls, although some bacterial taxa displayed to be enriched. This is the case for Akkermansia, which showed to be favored in E. coli colonized individuals, while notably reduced in the Blastocystis spp. parasitized group.

Blastocystis in Swiss children: a practical approach

Blastocystis is a parasite with a worldwide distribution and a varying prevalence in different countries. The pleomorphic nature of the protozoon and the lack of understanding a possible pathogenesis have led to confusion regarding its clinical significance. The aim of the study was to shed light on clinical characteristics of pediatric patients in Swiss children with a positive stool sample for Blastocystis, in order to provide recommendations for a practical approach for the clinician to know whom, when, and how to test. This is a retrospective study of pediatric patients, whose stool has been tested positive for Blastocystis in the last 10 years in northern Switzerland. A total of 4047 stool samples, belonging to 1887 different patients, were analyzed; 240 stool samples (of 160 patients) were tested positive for Blastocystis. On average, 2.2 (CI 1.98-2.35) stool samples per patient were analyzed, of which 1.48 (CI 1.36-1.61) were positive for Blastocystis. In 63% abdominal pain was the leading symptom, while in 17.5% it was an accidental finding without symptoms. There was a high significance in correlation of abdominal pain and chronicity (p < 0.0001) but none in diarrhea (p = 0.082) nor nausea/vomiting or other symptoms and chronicity. Followed by Entamoeba coli (8%), 26.3% of the patients with Blastocystis had a co-infection with another parasite, mostly Endolimax nana (13%).Conclusion: Carriage of Blastocystis is common; therefore, only children/teenagers at risk for a symptomatic Blastocystis infection should be tested. There is a good correlation between Blastocystis and chronic abdominal pain. Children with abdominal symptoms persisting over 4 weeks should have two different stool samples analyzed. No screening after travels/immigration is recommended.What is Known:• Blastocystis has a worldwide distribution.• The clinical significance is unclear.What is New:• Based on retrospective data, we recommend to only test children/teenagers with chronic abdominal pain for Blastocystis.• Two different stool samples should be examined by microscopy; serological investigations are not warranted.

Identification of Entamoeba histolytica in Patients with Suspected Amebiasis in Jordan Using PCR-based Assays

BACKGROUND AND OBJECTIVE

Identification of Entamoeba histolytica (E. histolytica) by microscopy alone can be problematic because E. dispar and E. moshkovskii are morphologically similar to E. histolytica. Therefore, this study aimed to assess the performance of microscopy in the detection of E. histolytica in stool specimens with the help of PCR-based assays and enzyme-linked immunosorbent assay (ELISA).

MATERIALS AND METHODS

Between September, 2017 and September, 2018, 200 stool specimens were obtained from Jordanian patients with suspected amebiasis. All specimens were subjected to microscopic analysis. DNA was extracted from the microscopy-positive stool samples. A conventional PCR and a duplex real-time PCR were performed to detect E. histolytica and E. dispar.

RESULTS

By microscopy, 35% (70/200) of specimens were tested positive for Entamoeba complex. All 70 microscopic-positive Entamoeba complex samples were negative for the presence of E. histolytica by the NOVITEC® E. histolytica ELISA assay. All 70 samples positive by microscopy were negative for the presence of E. histolytica and E. dispar by PCR-based assays.

CONCLUSION

We suspect some of these microscopy-positive stool specimens might contain a potentially novel species of Entamoeba that could not be detected by ELISA or PCR-based assays specific for E. histolytica and E. dispar. Diagnosis of amebiasis remains challenging here in Jordan and hence highlighting the need for improved diagnostic method.

Enteroparasitism and Risk Factors Associated with Clinical Manifestations in Children and Adults of Jalisco State in Western Mexico

Objectives

To determine the prevalence and risk factors associated with intestinal parasites in the population of San Juan Cosala, Jalisco, Mexico.

Methods

A total of 277 samples from 104 participants were analysed using direct smear, flotation, formaldehyde/ethyl acetate, and modified Kinyoun's acid-fast stain methods. The Graham method was applied only for samples from children under 12 years of age for the diagnosis of Enterobius vermicularis.

Results

The prevalence of parasite infections in the study population was 77.9% including: Entamoeba histolytica/E. dispar/E. moshkovskii/E. bangladeshi (37.5%), Giardia intestinalis (11.5%); commensals: Endolimax nana (44.2%), Entamoeba coli (27.9%), Chilomastix mesnili (6.7%) and Iodamoeba bütschlii, (2.9%); emerging intestinal protozoans: Blastocystis spp. (49%), Cryptosporidium spp. (7.7%) and Cyclospora cayetanensis (2.9%); and helminths: Enterobius vermicularis (18.3%) and Ascaris lumbricoides (5.8%). The results also showed that 58.64% of the studied population presented polyparasitism. A significant association was found between protozoan infections and housewives, and houses that were not built with concrete ceilings, brick walls and cement floors (p < 0.05).

Conclusion

Polyparasitism was observed in over half the study population. The most prevalent parasite was Blastocystis spp, whilst the prevalence of helminths was less than that of protozoans. The risk factors for infection to intestinal parasites were being a housewife and not having solid brick, cement and concrete materials for house construction.

Intestinal parasitism and nutritional status among indigenous children from the Argentinian Atlantic Forest: Determinants of enteroparasites infections in minority populations

OBJECTIVE

Intestinal parasitoses, especially in the less favored populations of tropical and subtropical areas, are a scourge of high impact in public health. We conducted a cross-sectional survey to investigate the prevalence of helminths and protozoa pathogens, malnutrition, and their determinants in children from indigenous Mbyá Guaraní villages of Iguazú, in the subtropical Atlantic Forest of Argentina.

METHODS

Parasitological assessment was performed using a combination of flotation, sedimentation, and centrifugation techniques, as well as temporal and permanent stains. Nutritional assessment was based on nutritional indicators derived from anthropometric measurements. Statistical analysis of socio-demographic determinants was assessed by Generalized Linear Mixed Models at individual, household, and village levels.

RESULTS

A total of 303 children from 140 families from Fortin Mbororé and Yriapú Jungle villages participated, and 87.8% of them resulted positive to at least one parasite. Multiparasitism reached 70% and children with up to six different parasites were detected. Thirteen genera were identified, of which eight were pathogenic. The most frequent soil-transmitted helminths were hookworms and Strongyloides stercoralis with 60.7 and 41.9%, respectively. Enterobius vermicularis was detected in 28.4% of children. Giardia duodenalis was the main protozoan and reached the 33.3%. The prevalence of stunting and underweight were 38.9% and 6.9%, whereas for overweight and obesity were 28.1% and 12.9%, respectively. An association was observed between stunting in older children and the presence of parasites, multiparasitism, and giardiasis. Individual conditions and habits were important determinants for most of the parasitoses.

CONCLUSIONS

We evidenced that the community is affected by the double burden of malnutrition and parasitoses. To face this alarming situation, public policies are needed to improve sanitation, hygiene education access, community deworming programs, and quality nutrition on a regular basis of intercultural approaches.

Horizontal transmission of Endolimax piscium, causative agent of systemic amoebiasis in Senegalese sole Solea senegalensis

Systemic amoebiasis of Senegalese sole Solea senegalensis is caused by Endolimax piscium Constenla, Padrós & Palenzuela, 2014 a cryptic parasitic member of the Archamoebae whose epidemiology is yet unknown. To test whether the parasite can be transmitted horizontally, an experimental trial by cohabitation between non-infected and infected fish was designed. Transmission of the parasite from naturally infected to healthy fish was confirmed in the experiment, with the water as the most likely route of infection. Under the conditions of the study, the infection process was remarkably slow, as parasites could be detected by in situ hybridization within the intestinal mucosa of recipient fish only after 17 wk of cohabitation, and none of the new hosts displayed clinical signs of disease. Long prepatent period and the need for additional triggering factors for the development of the clinical condition are suggested. The intestinal mucosa is proposed as the tissue where the amoeba can survive as endocommensal, but also as an invasion route from which the parasite would disperse to other organs.

Enteroparasites in Preschool Children on the Pacific Region of Nicaragua

The aim of this study was to determine for the first time the prevalence of enteroparasites in preschool children originating from the seven departments of the Pacific region in Nicaragua. One stool sample of each of 1,217 children, from 6 months to 5 years of age, was collected and personal data were recorded on delivery of the container. Samples fixed in 10% formalin were processed by a formol-acetate concentration and a modified Ziehl-Neelsen technique. The overall prevalence of enteroparasite infections was 68.2% with a total of at least 20 species. Blastocystis hominis (45.5%), Giardia intestinalis (31.7%), Trichuris trichiura (8.2%), and Ascaris lumbricoides (5.2%) were the most prevalent protozoa and helminth species in the total study as well as in all departments. Protozoan prevalence presented a statistically significant difference by gender (male: 69.6%; female: 46.7%; P < 0.001), and males presented a higher T. trichiura infection rate than females (male: 9.9%; female 6.4%; P < 0.035). Protozoan prevalence increased with age with a statistically significant difference (P < 0.001). Helminths were always more prevalent in urban areas (P < 0.0002). Protozoan infections result statistically higher than helminth infections so that water-based transmission could be suspected. Based on the differences with respect to species and parasite prevalence between the seven departments in the Pacific region of Nicaragua, the exploration of local factors associated with the transmission of enteroparasites should also be considered to reduce infection.

Molecular identification of Entamoeba species in savanna woodland chimpanzees (Pan troglodytes schweinfurthii)

To address the molecular diversity and occurrence of pathogenic species of the genus Entamoeba spp. in wild non-human primates (NHP) we conducted molecular-phylogenetic analyses on Entamoeba from wild chimpanzees living in the Issa Valley, Tanzania. We compared the sensitivity of molecular [using a genus-specific polymerase chain reaction (PCR)] and coproscopic detection (merthiolate-iodine-formaldehyde concentration) of Entamoeba spp. We identified Entamoeba spp. in 72 chimpanzee fecal samples (79%) subjected to species-specific PCRs for six Entamoeba species/groups (Entamoeba histolytica, Entamoeba nuttalli, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba coli and Entamoeba polecki ST2). We recorded three Entamoeba species: E. coli (47%), E. dispar (16%), Entamoeba hartmanni (51%). Coproscopically, we could only distinguish the cysts of complex E. histolytica/dispar/moshkovskii/nuttalli and E. coli. Molecular prevalence of entamoebas was higher than the prevalence based on the coproscopic examination. Our molecular phylogenies showed that sequences of E. dispar and E. coli from Issa chimpanzees are closely related to sequences from humans and other NHP from GenBank. The results showed that wild chimpanzees harbour Entamoeba species similar to those occurring in humans; however, no pathogenic species were detected. Molecular-phylogenetic methods are critical to improve diagnostics of entamoebas in wild NHP and for determining an accurate prevalence of Entamoeba species.

Systematic review on Endolimax nana: A less well studied intestinal ameba

Of the so-called nonpathogenic intestinal protozoa, Endolimax nana belongs to the ones least well described. Most data on E. nana have emerged from general surveys of intestinal parasites in selected cohorts and mostly in the absence of any particular focus on Endolimax. Hence, the genus of Endolimax remains largely unexplored in terms of morphology, taxonomy, genetic diversity, host specificity, and epidemiology. In this review, we seek to provide an overview of the work that has been performed on the parasite since the genus Endolimax was described by Kuenen and Swellengrebel in 1917 and suggest activities that may pave the way for a better understanding of E. nana in a clinical and public health context.

Prevalence of Intestinal Protozoa among Saudi Patients with Chronic Renal Failure: A Case-Control Study

It has been hypothesized that chronic renal failure (CRF) predisposes patients to infection with intestinal protozoa. We tested this hypothesis with a matched case-control study to determine the prevalence of these protozoa and their diarrhea associated symptoms among 50 patients with CRF (cases) from Taif, western Saudi Arabia. Fifty diarrheal patients without CRF were recruited in the study as controls. Participants were interviewed by a structured questionnaire and stool samples were collected. Samples were thoroughly examined with microscopy and three coproantigens detection kits. Enteric protozoa were detected in 21 cases and 14 controls. Blastocystis spp. were the most predominant parasite (16% in cases versus 8% in controls), followed by Giardia duodenalis (10% in cases versus 12% in controls) and Cryptosporidium spp. (10% in cases versus 6% in controls). Cyclospora cayetanensis was identified in two cases, while Entamoeba histolytica was described in one case and one control. Intestinal parasitism was positively associated with the male gender, urban residence, and travel history. Clinical symptoms of nausea/vomiting and abdominal pain were significantly varied between the parasitized cases and controls (P value ≤ 0.05). Given the results, we recommend screening all diarrheal feces for intestinal protozoa in the study's population, particularly those with CRF.

Differential diagnosis of Entamoeba spp. in clinical stool samples using SYBR green real-time polymerase chain reaction

Amoebiasis, a disease caused by Entamoeba histolytica, is usually diagnosed by microscopic examination, which does not differentiate the morphologically identical species of the E. histolytica/E. dispar complex. Furthermore, morphologically similar species such as Entamoeba hartmanni contribute to misidentification. Therefore, there is a need for more sensitive and specific methods. This study standardized a multiplex real-time PCR system for E. histolytica and E. dispar and a single real-time PCR for E. hartmanni. The multiplex protocol detected up to 0.0143 pg of E. histolytica DNA and 0.5156 pg of E. dispar DNA, and the average melting temperature (T(m)) was 73 °C and 70 °C, respectively. For E. hartmanni, the T(m) was 73 °C and the amplification was successful down to 0.03 fg of plasmid DNA. Negative controls and other intestinal parasites presented no amplification. Among the 48 samples tested, E. dispar DNA was detected in 37; none exhibited E. histolytica DNA and 11 were negative in the multiplex protocol. In 4 of these 11 samples, however, E. hartmanni DNA was amplified. SYBR Green is demonstrated to be an interesting option and these combined PCR reactions can improve laboratory diagnosis of amoebiasis in developing countries.

Abdominal pain and asthenia as common clinical features in hospitalized children for giardiasis

Giardiasis is a disease with worldwide distribution, although its prevalence differs from country to country. In order to investigate the clinical pattern of giardiasis in in-patient children, a case-control study was carried out. In-patient children who had Giardia lamblia infection were compared with non Giardia-infected children, focusing only on 4 clinical manifestations: diarrhoea, abdominal pain, asthenia and vomiting. In multivariable analysis, abdominal pain (odds ratio [OR] 4.71, 95% confidence intervals [CI] 2.66-8.32) and asthenia (OR 3.30, 95% CI 1.16-9.37) had positive and independent associations with Giardia infection. The present study supports the potential role of G. lamblia in abdominal pain in children who attend- and are admitted- to a hospital in Havana City, and highlights the importance to keep abdominal pain and asthenia in mind in hospital admitted children in the event of an association with an evocative epidemiological context.