Blastocystis: to treat or not to treat

Blastocystis hominis as a cause of chronic diarrhea in low-resource settings: A systematic review

BACKGROUND

Blastocystis hominis (B. hominis), an anaerobic unicellular protist parasite, is known for its diverse clinical manifestations upon infecting the human gastrointestinal tract. Although globally distributed, it is particularly prevalent in developing nations. Examining the symptoms and treatment outcomes of B. hominis infection in low-resource settings holds immense significance, providing healthcare practitioners with valuable insights to enhance patient care.

AIM

To synthesize existing evidence on the symptomatology and treatment outcomes of B. hominis infection in low-resource settings.

METHODS

Following the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines, a systematic review was conducted. The search spanned electronic databases including PubMed, Scopus, and Google Scholar. After a comprehensive screening process, a thorough examination of the papers, adhering to inclusion and exclusion criteria, and data extraction from eligible studies was conducted. The findings underwent summarization through simple descriptive analysis.

RESULTS

The search yielded 1200 papers, with 17 meeting inclusion criteria. Chronic diarrhea due to B. hominis infection was reported in only two studies, while abdominal pain, diarrhea, flatulence, constipation, and nausea/vomiting emerged as the most commonly documented symptoms. Recovery rates after one week of treatment ranged from 71.8% to 100%, and after two weeks, from 60% to 100%.

CONCLUSION

In low-resource settings, chronic diarrhea resulting from B. hominis infection is infrequent. Common symptoms include abdominal pain, diarrhea, flatulence, constipation, and nausea/vomiting. Post-treatment, clinical outcomes are notably favorable, supporting the recommendation for treatment. Metronidazole is advocated as the first-line agent, with consideration for switching to a second-line option in cases of treatment failure or poor response.

The influence of plant extracts on viability of ST3 and ST7 subtypes of Blastocystis sp

Blastocystis sp. is one of the most frequently detected protozoa during stool specimen examination. In the last decade, the studies about the pathogenic potential of Blastocystis sp. have intensified. Additionally, treatment approaches against this parasite are still disputable. The study aimed to investigate the in vitro activity of the substances of natural origin against two subtypes (ST) of Blastocystis sp.-ST3 and ST7. Garlic and turmeric extracts exhibited the highest inhibitory effect in relation to the ST3 viability. While horseradish and turmeric were found to be the most effective extracts to the ST7 viability. The study showed that ginger, garlic, horseradish, and turmeric extracts have potent antimicrobial activity against Blastocystis ST3 and ST7, with the half-maximal inhibitory concentration (IC50) ranging from 3.8 to 4.8 µg/ml and from 3.3 to 72.0 µg/ml, respectively, and thus may be useful in the prevention and control of Blastocystis infections. Additionally, this research confirmed that Blastocystis ST7 is more resistant to the selected plant extracts treatment than Blastocystis ST3 which in consequence may bring some difficulties in its eradication.

Blastocystis: A Mysterious Member of the Gut Microbiome

Blastocystis is the most common gastrointestinal protist found in humans and animals. Although the clinical significance of Blastocystis remains unclear, the organism is increasingly being viewed as a commensal member of the gut microbiome. However, its impact on the microbiome is still being debated. It is unclear whether Blastocystis promotes a healthy gut and microbiome directly or whether it is more likely to colonize and persist in a healthy gut environment. In healthy people, Blastocystis is frequently associated with increased bacterial diversity and significant differences in the gut microbiome. Based on current knowledge, it is not possible to determine whether differences in the gut microbiome are the cause or result of Blastocystis colonization. Although it is possible that some aspects of this eukaryote's role in the intestinal microbiome remain unknown and that its effects vary, possibly due to subtype and intra-subtype variations and immune modulation, more research is needed to characterize these mechanisms in greater detail. This review covers recent findings on the effects of Blastocystis in the gut microbiome and immune modulation, its impact on the microbiome in autoimmune diseases, whether Blastocystis has a role like bacteria in the gut-brain axis, and its relationship with probiotics.

The clinical significance of Dientamoeba fragilis and Blastocystis in human stool-retrospective cohort study

OBJECTIVES

The aim of this study was to assess the clinical significance of Dientamoeba fragilis (DF) and Blastocystis species (Bs) in human stool.

METHODS

Observational study of patients ≥18 years, who were tested by stool multiplex PCR for bacteria and parasites between April 2019 and March 2022. Although DF and Bs are part of the PCR kit, these results are not routinely reported to the patient or the ordering physician. The main outcomes were the incidence of symptoms during 14 days before the referral to stool PCR test, and the incidence of several clinical outcomes during 60 days after the PCR test (symptoms, referrals to further evaluation, prescription of symptomatic, or antibiotic treatment).

RESULTS

A total of 27 918 patients were tested by stool PCR during the 3 study years. A total of 6215 (22.3%) and 5337 (19.2%) were positive for DF and Bs, respectively. The incidence of symptoms before the test was similar in those positive for Bs or DF and those with all-negative PCR (adjusted OR and 95% CI of 0.87 [0.80-0.95] and 0.82 [0.76-0.88] for Bs and DF, respectively), whereas significantly higher (2.47 [2.23-2.73]) in those positive for the other multiplex PCR assay components. During the 60 days after the test, the prevalence of any of the outcomes was similar in those positive for Bs or DF and those with negative PCR (adjusted OR and 95% CI of 0.92 [0.83-1.02] and 0.89 [0.81-0.97] for symptoms, 0.84 [0.75-0.94] and 0.93 [0.85-1.01] for referrals, 0.88 [0.75-1.03] and 0.82 [0.71-0.94] for symptomatic treatment, and 0.88 [0.75-1.02] and 0.86 [0.75-0.98] for antibiotic treatment in the Bs and DF positive individuals, respectively). The PCR cycle threshold was not associated with any of the outcomes.

DISCUSSION

Positive stool PCR for DF or Bs was not associated with any of the measured clinical outcomes.

Metataxomics reveals Blastocystis subtypes mixed infections in Colombian children

Blastocystis sp., is an intestinal protist with a broad host range and a high prevalence in human populations worldwide, even in developed Western countries. The publication of conflicting evidence has divided the scientific community about the pathogenic role of this parasite. Even though, genetic studies on Blastocystis sp. revealed associations between genotypes and different pathogenic profiles. Conventionally, the detection of this parasite is based on microscopic or PCR methods, which offer meager or null performance in detecting mixed infections. In this work, we applied a metataxonomic NGS approach targeting the V4 region of the eukaryotic SSU-rRNA gene and classical phylogenetic methods. This approach allowed us to detect Blastocystis sp. in stool samples from infected children living in an urban setting in the city of Medellin attending the same daycare center. Phylogenetic analysis identified the subtypes present in the children as ST1, ST2, and ST3. Besides, mixed infections of subtypes ST1 + ST3 were spotted in 16% of the analyzed stool samples.

Epidemiology of Blastocystis Infection: A Review of Data from Poland in Relation to Other Reports

Blastocystis is a common gut protist of humans and various animals worldwide, with a high level of genetic diversity. Neither its zoonotic potential and transmission routes nor its pathogenicity are fully known. This fact, and the fact that Blastocystis is the most abundant eukaryote in human faeces, raises the question of its relevance to public health. Here, we summarise (in relation to other reports) the results of studies on the prevalence and genotypic variation of Blastocystis, which were carried out in animals, humans, and in water environments in Poland. In humans, the prevalence ranged between 0.14 and 23.6%, in some animals reached 58.97%, and in water environments was 5.1%. Seven subtypes were identified in humans (ST1-ST4, ST6, ST7, and ST9), of which ST3 was the most common. Among animals (wild, livestock, and pet animals), eleven STs were identified, with differential host specificity. Humans and animals shared ST1, ST2, ST3, ST6, and ST7, while ST1 and ST3 were present in humans, animals, and water sources. These observations indicate the possibility of Blastocystis transmission between animals and humans. Further studies should be continued in search of the sources and transmission routes of Blastocystis in order to prevent the spread of infections among humans and animals.

Intestinal Parasitic Infections in 2023

Intestinal parasites include intestinal protozoa and intestinal helminths. Intestinal parasitic infections (IPIs) pose a global health problem affecting over one billion people worldwide. Although these infections are predominantly seen in the developing world, they are frequently seen in the developed countries, particularly in immunocompromised patients. Patients' clinical presentations generally include diarrhea, dysentery, abdominal pain, nausea, vomiting, nutritional deficiency, iron deficiency anemia, anal and perianal itching, and rarely intestinal obstruction. The intestinal parasites have similarities in their mode of transmission and life cycle. The stool test is the primary way of diagnosing IPIs. Treatment is given with various anti-parasitic agents. However, appropriate preventive measures are essential for successfully controlling the IPIs.

Possible microRNA-based mechanism underlying relationship between chronic spontaneous urticaria and Blastocystis

BACKGROUND

Blastocystis spp. has been proposed as a possible cause of extraintestinal clinical signs such as urticaria pathogenesis.

OBJECTIVES

The aim of this study was to investigate the differences between microRNA (miRNA) expression profiles of Chronic spontaneous urticaria (CSU) patients in the presence or absence of Blastocystis spp. as well as healthy controls. Additionally, cellular pathways which are affected in the presence of Blastocystis spp. were identified.

METHODS

Twenty patients diagnosed with CSU were enrolled in the study and divided into equally two groups according to the presence of Blastocystis spp. Besides, six healthy individuals were included in the study. The expression profiles of 372 human-derived miRNAs have been investigated in serum samples from CSU patients and healthy controls with miScript miRNA PCR Array Human miRBase Profiler.

RESULTS

Compared to Blastocystis-negative (BN)-CSU patients, expression of 3 miRNAs (hsa-miR-3183, hsa-miR-4469, hsa-miR-5191) were found to be downregulated by at least two-fold (p < 0.05) in Blastocystis-positive (BP)-CSU patients. Additionally, the miRNA expression profiles of six healthy individuals (n = 3 Blastocystis-positive, n = 3 Blastocystis-negative) were analyzed and it was determined that the expressions of 7 miRNAs (hsa-miR-4661-5p, hsa-miR-4666a-5p, hsa-miR-4803, hsa-miR-5587-5p, hsa-miR-4500, hsa-miR-5680, hsa-miR-382-3p) increased at least 3-fold in the serum of individuals with Blastocystis-positive compared to Blastocystis-negative subjects. Most down-regulated miRNAs, in BP-CSU patients, affect cell adhesion molecules (CAMs), and signaling pathways therefore, Blastocystis spp. presence may influence the clinical presentation of urticaria by leading to unbalanced immunity. In addition, Blastocystis spp. presence may be influenced TGF- β signaling pathway through altered miRNAs and may be laying the groundwork for the development of CSU in healthy individuals.

CONCLUSIONS

As a consequence, this is the first report to show that the miRNA expression profile is affected by the presence of Blastocystis spp. Further miRNA-based studies are needed in order to enlighten the exact underlying molecular mechanisms of the relationship between Blastocystis spp. and CSU.

Frequency, spatial distribution, and genetic diversity of Blastocystis among referred individuals to a clinical laboratory: First report of subtype 9 in Brazil

The enteric protist Blastocystis has a worldwide distribution, however its prevalence in the human population is still underestimated, especially in developing countries where proper diagnosis is not performed in the routine of clinical laboratories. In this study, we aimed to assess the frequency, genetic diversity, and spatial distribution of Blastocystis isolates detected in fecal samples referred to a clinical laboratory for routine examination in inner São Paulo State, Brazil. A total of 348 leftover stool samples available for disposal from female and male individuals with age ranging from 3 months to 88 years were analyzed by both microscopic examination and PCR/sequencing of the SSU rRNA gene. The overall frequency of Blastocystis sp. was 31% (108/348), including 20.1% (70/348) and 31% (108/348) by microscopic examination and PCR/sequencing, respectively. Significant association was found only between Blastocystis infection and age, since the highest rate of positive samples was detected among 5-9 years old individuals (p < 0.0001). In addition, spatial distribution revealed a wide distribution of the positive samples, however they were densely concentrated in more populated areas. Seven subtypes were identified, namely ST1 (40.7%), ST2 (9.2%), ST3 (45.3%), ST4 (0.9%), ST6 (1.8%), ST7 (0.9%) and ST9 (0.9%). The intra-subtype analysis revealed a total of 25 different alleles previously reported. Here, the findings lead us to highlight the following aspects: (1) the identification of a ST9 isolate is a relevant finding since it is considered a very rare subtype in human infections as well as this is the first report in Brazil; (2) the high frequency of Blastocystis in fecal samples submitted for examination in a clinical laboratory points to the need to consider its search in routine parasitological examinations, (3) the spatial distribution of Blastocystis infection was not homogeneous but concentrated in more populated areas where the access for population to diagnostic services in healthcare is likely to be easier and, (4) the genetic variability of Blastocystis isolates suggests exposure of inhabitants living in inner municipalities to different sources of contamination involving anthroponotic and zoonotic transmission pathways.

Acquired long QT syndrome due to antiemetics, COVID-19 and Blastocystis hominis induced exacerbation of congenital chloride losing diarrhoea

Congenital chloride losing diarrhoea (CCLD) is a rare disease caused by mutations in an intestinal chloride/bicarbonate ion exchange channel. Few reports describe CCLD in adults and none has described the impact of a parasitic infection on CCLD. Severe diarrhoea may result in hypokalaemia with QT interval prolongation. Treatment with antiemetics may further increase the QT interval. To raise awareness of this preventable complication, we describe the course of a woman in her 20s with CCLD who developed COVID-19 and a Blastocystis hominis infestation. Treatment with antiemetics and hypokalaemia resulted in prolongation of the QT interval to 640 ms. While, the QT interval normalised with discontinuation of antiemetics and electrolyte replacement, patients with CCLD must take precautions to prevent gastrointestinal infections. Regardless, whenever patients with CCLD present to hospital, the authors recommend monitoring the QT interval and avoiding medications that predispose to torsade de pointes.

Zoonotic Transmission of Blastocystis Subtype 1 among People in Eastern Communities of Thailand: Organic Fertilizer from Pig Feces as a Potential Source

Blastocystis sp., the most common intestinal protozoa, remains a public health problem among people in many countries, particularly in rural areas of developing countries. The infection usually reflects poor sanitation in communities by waterborne, zoonotic, and person-to-person transmission. Interestingly, at least 17 subtypes (STs) have been reported and are associated with a broad range of animal hosts, including humans. In this study, we reported potential evidence of zoonotic transmission of Blastocystis ST1 in rural communities of eastern Thailand where the overall prevalence of Blastocystis infection was 15.7%. Two major and three minor subtypes were found to be distributed unequally in this region. Of 5 STs, only ST1 was found to be associated with pig feces in an open farm system that produced organic fertilizer for agriculture uses in the community. This finding suggests that properly protective contact and standard production of organic fertilizer from pig feces by-products could be key factors for reducing the prevalence of Blastocystis infection and prevent Blastocystis reinfection among people in the community.

IMPORTANCEBlastocystis sp. remains a public health problem among people, particularly in rural areas of many developing countries. The infection usually reflects poor sanitation in communities by waterborne, zoonotic, and person-to-person transmission. In this study, we reported potential evidence of zoonotic transmission of Blastocystis subtype 1 (ST1) in rural communities of eastern Thailand. Two major and three minor subtypes were found to be unequally distributed in this region. Interestingly, only ST1 was found to be associated with pig feces in an open farm system that produced organic fertilizer for agriculture uses in the community. The finding makes significant contributions to genetic and molecular investigations of microbial topics of practical value and suggest that properly protective contact and standard production of organic fertilizer from pig feces by-products could be key factors for reducing the prevalence of Blastocystis infection and prevent Blastocystis reinfection among people in the community.

Utilizing Probiotics for the Prevention and Treatment of Gastrointestinal Diseases

Probiotics are heavily advertised to promote a healthy gastrointestinal tract and boost the immune system. This review article summarizes the history and diversity of probiotics, outlines conventional in vitro assays and in vivo models, assesses the pharmacologic effects of probiotic and pharmaceutical co-administration, and the broad impact of clinical probiotic utilization for gastrointestinal disease indications.

The effect of Blastocystis sp. and Dientamoeba fragilis on psychological symptom severity in a sample of clinically diverse males and females

Health outcomes associated with Blastocystis sp. and Dientamoeba fragilis are disparate and controversial, ranging from health benefits, to years of asymptomatic carriage, through to severe illness. Evidence that Blastocystis sp. and D. fragilis are commensal members of the gut microbiota is growing. Despite this, little to no research exists investigating the potential effect of these protozoa on psychological symptom expression. As such, the aim of this retrospective cross-sectional study was to be the first to investigate the effect of protozoan carriage on severity of Depressive, Neurocognitive, Stress and Anxiety, and Sleep and Fatigue symptoms, and whether this effect changes as a function of sex. The prevalence of D. fragilis was significantly higher in females compared to males, however there were no sex differences in prevalence for Blastocystis sp. (data used in the current study contained ST1, ST3, and Blastocystis ST unspecified) or co-carriage of the two. Females reported significantly more severe symptoms across all four psychological domains compared to males. There was no significant interaction between sex and Blastocystis sp. carriage on psychological symptom severity, and no significant main effect of Blastocystis sp. on symptom severity compared to those who tested negative for protozoa. When investigating the sexes separately, there was no effect of protozoan carriage on psychological symptom expression in either males or females. These findings add weight to the argument that Blastocystis sp. and D. fragilis are not necessarily pathogenic and are likely to be part of a diverse gut (which is typically associated with better health outcomes). Further research is required given that protozoan members of the gut microbiota have been largely ignored in brain-gut-microbiota axis research.

Influence of Proton Pump Inhibitors and Histamine Receptor 2 Antagonists on Blastocystis ST3 and Selected Microorganisms of Intestinal Microbiota In Vitro

INTRODUCTION

Proton pump inhibitors (PPIs) and histamine receptor 2 (H2) antagonists are commonly prescribed medications. Association between PPIs and alteration of the gut microbiota has been reported. Blastocystis, the most common intestinal protozoan worldwide, occurs in both healthy and symptomatic people with gastrointestinal or cutaneous disorders, with controversial pathogenicity. The current study was aimed to investigate the influence of PPIs and H2 blockers on the in vitro proliferation of selected intestinal bacteria, fungi, and protozoa.

METHODS

Cultures of Lactobacillus rhamnosus, Escherichia coli, Enterococcus faecium, Candida albicans, and Blastocystis subtype 3 were treated with different concentrations of respective medications in vitro, and the numbers of microorganisms were quantified and compared.

RESULTS

Pantoprazole and esomeprazole exerted a significant inhibition on Blastocystis and C. albicans, especially at higher concentrations, which were even more effective than metronidazole. On the other hand, treatment with pantoprazole caused an increase in proliferation of L. rhamnosus and E. coli. There was no influence of H2 blockers on the examined microorganisms.

DISCUSSION

PPIs, such as pantoprazole, can be a potential treatment in the prophylaxis or eradication of Blastocystis and C. albicans.

Promising Anti-Protozoan Activities of Propolis (Bee Glue) as Natural Product: A Review

PURPOSE

Propolis (bee glue) is a resinous mixture of different plant exudates that possesses a wide range of biological and antimicrobial activities and has been used as a food supplement and in complementary medicine for centuries. Some researchers have proposed that propolis could be a potential curative compound against microbial agents such as protozoan parasitic infections by different and occasionally unknown mechanisms due to the immunoregulatory function and antioxidant capacity of this natural product.

METHODS

In this review, we concentrate on in vitro and in vivo anti-protozoan activities of propolis extracts/fractions in the published literature.

RESULTS

In Leishmania, propolis inhibits the proliferation of promastigotes and produces an anti-inflammatory effect via the inhibition of nitric oxide (NO) production. In addition, it increases macrophage activation, TLR-2, TNF-α, IL-4, IL-17 production, and downregulation of IL-12. In Plasmodium and Trypanosoma, propolis inhibits the parasitemia, improving anemia and increasing the IFN-γ, TNF-α, and GM-CSF cytokines levels, most likely due to its strong immunomodulatory activity. Moreover, propolis extract arrests proliferation of T. cruzi, because it has aromatic acids and flavonoids. In toxoplasmosis, propolis increases the specific IgM and IgG titers via decreasing the serum IFN-γ, IL-1, and IL-6 cytokines levels in the rats infected with T. gondii. In Cryptosporidium and Giardia, it decreases oocysts shedding due to phytochemical constituents, particularly phenolic compounds, and increases the number of goblet cells. Propolis inhibits the growth of Blastocystis, possibly by apoptotic mechanisms like metronidazole. Unfortunately, the mechanism action of propolis' anti-Trichomonas and anti-Acanthamoeba is not well-known yet.

CONCLUSION

Reviewing the related literature could highlight promising antimicrobial activities of propolis against intracellular and extracellular protozoan parasites; this could shed light on the exploration of more effective drugs for the treatment of protozoan parasitic infections in the near future.

Seasonal prevalence, risk factors, and One Health intervention for prevention of intestinal parasitic infection in underprivileged communities on the Thai-Myanmar border

BACKGROUND

Tha Song Yang District, located on the Thai-Myanmar border, contributes to the second highest cases of amoebic dysentery due to intestinal parasitic infections (IPI). However, there were limited disease prevalence data, specific surveillance systems, and interventions available.

OBJECTIVE

This study aimed to explore the epidemiological features of the IPIs and apply the One Health (OH) approach to solve IPI-related problems.

METHODS

Prevalence of asymptomatic infections in human and animals, yearly symptomatic cases, and associated risk factors were investigated. The OH intervention included improving the knowledge, attitude, and practice (KAP) of the community, microscopic diagnosis training, and stakeholder engagement for IPI prevention designs.

RESULTS

The prevalence of asymptomatic cases was much higher than that of the symptomatic cases. Infective stages of the intestinal parasites were discovered in animal stool and water samples, indicating possible transmission routes. One year after the intervention, there were significant declines in asymptomatic IPIs and symptomatic cases of amoebic dysentery. Significant improvements in KAP and awareness regarding water and manure-waste management of the community were observed.

CONCLUSION

We reported the successful application of the OH intervention in reducing the IPI prevalence and mitigating disease-related risks. The intervention might be applied to address other infectious diseases in the future.

In vitro susceptibility of human Blastocystis subtypes to simeprevir

Introduction and aim

Blastocystis is a common enteric parasite, having a worldwide distribution. Many antimicrobial agents are effective against it, yet side effects and drug resistance have been reported. Thus, ongoing trials are being conducted for exploring anti-Blastocystis alternatives. Proteases are attractive anti-protozoal drug targets, having documented roles in Blastocystis. Serine proteases are present in both hepatitis C virus and Blastocystis. Since drug repositioning is quite trendy, the in vitro efficacy of simeprevir (SMV), an anti-hepatitis serine protease inhibitor, against Blastocystis was investigated in the current study.

Methods

Stool samples were collected from patients, Alexandria, Egypt. Concentrated stools were screened using direct smears, trichrome, and modified Ziehl-Neelsen stains to exclude parasitic co-infections. Positive stool isolates were cultivated, molecularly subtyped for assessing the efficacy of three SMV doses (100,150, and 200 μg/ml) along 72 hours (h), on the most common subtype, through monitoring parasite growth, viability, re-culture, and also via ultrastructure verification. The most efficient dose and duration were later tested on other subtypes.

Results

Results revealed that Blastocystis was detected in 54.17% of examined samples. Molecularly, ST3 predominated (62%), followed by ST1 (8.6%) and ST2 (3.4%). Ascending concentrations of SMV progressively inhibited growth, viability, and re-culture of treated Blastocystis, with a non-statistically significant difference when compared to the therapeutic control metronidazole (MTZ). The most efficient dose and duration against ST3 was 150 µg/ml for 72 h. This dose inhibited the growth of ST3, ST1, and ST2 with percentages of 95.19%, 94.83%, and 94.74%, successively and viability with percentages of 98.30%, 98.09%, and 97.96%, successively. This dose abolished Blastocystis upon re-culturing. Ultra-structurally, SMV induced rupture of Blastocystis cell membrane leading to necrotic death, versus the reported apoptotic death caused by MTZ. In conclusion, 150 µg/ml SMV for 72 h proved its efficacy against ST1, ST2, and ST3 Blastocystis, thus sparing the need for pre-treatment molecular subtyping in developing countries.

[Current view on Blastocystis species: clinical forms, diagnosis and treatment]

The symptomatic form of Blastocystis spp. infection not only with mild diarrhea or dysentery-like syndrome, but also with the development of severe ulcerative necrotic lesions of the intestine. Meanwhile, the pathogenicity of these microorganisms should not be exaggerated, due to majority asymptomatic cases or infection transmission with minor impaired bowel function.

Acute gastroenteritis due to Blastocystis hominis in an adolescent boy

Acute gastroenteritis with persistent vomiting, high degree fever and blood streaking stools often suggests bacterial aetiology in children. Authors report a 13-year-old boy presenting with acute watery diarrhoea with persistent vomiting, fever of 103°F, abdominal cramps and blood streaking stools who failed to show any response to parenteral third-generation cephalosporin for 72 hours. The stool examination revealed numerous cystic and amoeboid forms of Blastocystis hominis Metronidazole was started and the boy promptly responded within 24 hours. There was no recurrence of symptoms then onwards. The case highlights the crucial stool examination in case of acute diarrhoeal disease for rare aetiology.

In vitro Effect of Silver Nanoparticles on Blastocystis hominis

INTRODUCTION

This study aims to assess the efficacy of silver nanoparticles (Ag Nps) alone and combined with metronidazole (Ag Nps + MTZ) as potential alternative therapeutic agents for Blastocystis hominis.

METHODS

The parasites were challenged with Ag Nps, Ag Nps + MTZ and MTZ. To assess the efficacy of drugs, counting of viable parasites was done after 1, 2, and 3 hours of adding the drugs.

RESULTS

Blastocystis hominis count was reduced by 20.72%, 28.23%, and 18.92% after one hour of adding Ag Nps, Ag Nps + MTZ, and MTZ, respectively. Cysts count was further reduced by 51.49%, 61.61%, and 40.78% after 2 hours and by 71.69%, 79.67%, and 62.65% after 3 hours of adding the drugs in the same order, respectively.

CONCLUSION

There was a statistically significant difference (P<0.05) in the in vitro growth inhibition of the parasite over the different time intervals when using the tested drugs against the control drug.

Two-day enema antibiotic therapy for parasite eradication and resolution of symptoms

BACKGROUND

Blastocystis hominis (B. hominis) and Dientamoeba fragilis (D. fragilis) are two protozoan parasites of human bowel that are found throughout the world. There is still debate about the pathogenicity of these protozoans, despite them being commonly associated with gastrointestinal symptoms and can cause health issue in both children and adults. These parasites are usually transmitted through faecal-oral contact particularly under poor hygiene conditions or food/water contamination. Once a person is infected, the parasites live in the large intestine and are passed in the faeces.

AIM

To investigate the effect of triple antibiotic therapy using enema infusion in the treatment of B. hominis and D. fragilis infections.

METHODS

This retrospective longitudinal study was conducted in a single medical centre, which included fifty-four patients (≥ 18 years) who were positive for D. fragilis, B. hominis or both between 2017 and 2018. The treatment consisted of triple antibiotics that were infused over two consecutive days through rectal enema. Faecal samples were collected from participants pre- and post-treatment and were tested for parasites using microscopy and polymerase chain reaction. Patients’ symptoms were recorded prior and after the treatment as well as patient demographic data.

RESULTS

Patients (n = 54), were either positive for B. hominis (37%), D. fragilis (35%) or both (28%). All patients completed the two-day treatment and no serious adverse effect was reported. The most common side effect experienced by the patients during the treatment was urine discolouration which was cleared by six weeks of follow-up. Common symptoms reported prior to treatment were diarrhoea, abdominal pain, constipation and fatigue. Other symptoms included abdominal discomfort, dizziness and blood in the stool. Eighty-nine percent of patients completed a final stool test post-treatment. At six weeks post-treatment, 79% of patients cleared the parasites from their faeces. Symptoms such as abdominal discomfort, dizziness and blood in the stool decreased significantly at both seven days and six weeks post-treatment (P < 0.040). The enema retention time, bowel preparation, previous antibiotic treatment or previous gastrointestinal problems had no significant effect on parasite eradication.

CONCLUSION

Overall, eradication of parasites and improvement of clinical outcomes were observed in treated patients, showing the efficacy of this combination to eradicate the parasites and provide positive clinical outcome.

Culture isolation and molecular identification of Blastocystis sp. in Brazilian human isolates: preliminary results

Blastocystis sp. is a protist commonly found in stool samples of humans and animals. Biological and genetic factors of this organism remain controversial. The present study aimed to develop and implement the Blastocystis in vitro culture of Brazilian human isolates for routine use. The fecal isolates (n = 20) were maintained in our laboratory by several passages in Pavlova's medium. Cultures were monitored every 72 h by light microscopy. Genomic DNA was extracted to identify the subtypes (STs). In most isolates, the vacuolar form was prevalent. The amoeboid, granular and cystic forms were observed during in vitro cultivation. STs 1, 2, 3, 4 and 7 were identified. Our preliminary results show the generation time and forms present in the in vitro culture of Blastocystis subtypes isolated from Brazilian human isolates. Therefore, we emphasize the use of in vitro culture as a tool in future studies for the better understanding of the biological aspects of Blastocystis sp.

An audit of inpatient stool ova and parasite (O&P) testing in a multi-hospital health system

Background & Objectives

Stool ova and parasite (O&P) examinations are routinely ordered initial tests in patients admitted to the hospital with acute diarrhea, despite low test positivity rates. We examined the diagnostic yield of inpatient stool O&P exams and identified risk factors associated with positive tests.

Methods

A retrospective, case-control analysis of inpatients admitted with diarrhea, who underwent O&P examination, was conducted. Clinical and demographic variables of cases were compared with age-and gender-matched controls via uni- and multivariate conditional logistic regression analyses.

Results

The yield of inpatient O&P exams was 2.15% (37/1723). Blastocystisspp. represented the most common parasites. All patients with positive tests, excluding Blastocystisspp., had at least one of the following risk factors: smoking, prior parasitic disease, HIV-positive status, travel to an endemic area, and institutionalization.

Conclusions

Superfluous inpatient stool O&P exams confer a financial and labor burden to hospital systems. Stool O&P exams should be restricted to individuals admitted to the hospital for <3 days, having diarrhea >7 days and possessing at least one of the following risk factors: smoking, prior parasitic disease, HIV-positive status, travel to an endemic area, and institutionalization. Such selective testing can confer a 51% reduction in testing, costs, and labor.

Blastocystis, urticaria, and skin disorders: review of the current evidences

Blastocystis is one of the most common intestinal protozoan parasites worldwide, which is linked to cutaneous lesions and urticaria. In a setting of systematic review, the data on the association of Blastocystis infection with cutaneous lesions were searched in order to summarize the main clinical symptoms, diagnostic methods, treatment, and outcome of the patients. The search identified 28 eligible articles, including 12 cross-sectional studies and 16 case reports/case series (including 23 cases). A diverse spectrum of skin symptoms, mainly urticaria, rash, and itching, was reported from the studies. Of the 23 infected cases with the skin symptoms, gastrointestinal symptoms were reported from the 16 cases, whereas 7 cases with urticaria had asymptomatic infection. The most frequent subtypes were ST1, ST2, and ST3, respectively. Metronidazole, paromomycin, and tinidazole were the most prescribed drugs in patients with single Blastocystis infection. Notably, urticaria and other cutaneous symptoms of all treated patients were resolved after treatment. In conclusion, this study indicates that Blastocystis infection can be a neglected cause of urticaria and skin disorders. Since the treatment of Blastocystis infection is simple, screening and treatment of this infection should be considered in patients with urticaria and other skin disorders.

Prevalence of Intestinal Parasites in a Low-Income Texas Community

Strongyloidiasis affects an estimated hundreds of millions of people worldwide, with infection possibly persisting for life without appropriate therapy because of the helminth's unique autoinfection cycle. Like other soil-transmitted helminths, because of the environmental conditions required for the life cycle of Strongyloides stercoralis, this parasite is endemic to tropical, subtropical, and temperate countries and areas with inadequate sanitation infrastructure. Given continued poverty and that nearly one in five American homes are lacking proper sanitation systems, many U.S. regions are at risk for intestinal parasites. A central Texas community was chosen as the study site, given previous reports of widespread sanitation failure, degree of poverty, and community willingness to participate. A total of 92 households were surveyed and residents tested for nine intestinal parasites using a multi-parallel quantitative real-time polymerase chain reaction and ELISA serology. From 43 stool samples, 27 (62.8%) tested positive for Blastocystis spp. and one (2.3%) for Giardia lamblia. From 97 serum samples, Strongyloides serology detected 16 (16.5%) positive individuals. These high rates of heterokont and helminthic laboratory findings in a peri-urban central Texas community suggest several key policy implications, including that strongyloidiasis should be added to the Texas notifiable conditions list, that clinical suspicion for this infection should be heightened in the region, and that residents without access to functioning and sustainable sanitation infrastructure should be provided that access as a basic human right and to promote public health.

Prevalence and subtype distribution of Blastocystis sp. infecting children from a rural community in Panama

Blastocystis sp. is a commonly reported intestinal parasite with a worldwide distribution. Phylogenetic analyses describe at least 17 subtypes for this parasite, and nine of them have been found in humans. However, the prevalence and some epidemiological characteristics of this parasitic infection in rural communities are not well known. The objective of this cross-sectional study was to evaluate the prevalence, subtypes, and epidemiological factors related to Blastocystis sp. Infection in children from of a small rural community in the central area of Panama. For this, 66 fecal samples from children (1 to 12 years old), were initially analyzed for the presence of parasites by a formalin-ethyl acetate/concentration method. Molecular detection and identification of Blastocystis sp. subtypes were carried out by amplification and sequencing of a partial fragment of the small-subunit ribosomal RNA gene. Using data from a questionnaire, analyses of epidemiological conditions potentially associated with Blastocystis sp. transmission were also conducted. Microscopic diagnostics showed that 33.3% (22/66) of the analyzed samples presented entero-parasites. Among them, Blastocystis sp. was the most prevalent, with 21.2% (14/66), followed by the E. histolytica/dispar/moshkovskii complex 4.5% (3/66), Giardia lamblia 1.5% (1/66) and Strongyloides stercoralis 1.5% (1/66). PCR-based analyses detected a prevalence of Blastocystis sp. infection of 74.2% (49/66) in apparently healthy children. Phylogenetic analysis revealed two different subtypes of this parasite: ST1 with 42.2% (28/66) infected, and ST3 with 31.8% (21/66) infected. In addition, recent diarrhea was significantly associated with Blastocystis sp. infection. None of the other risk factors evaluated was statistically associated with infection. These results highlight the need to further investigate clinical, epidemiological, and genetic characteristics of Blastocystis sp. infections in this community.

In vitro toxicity evaluation of short cationic antimicrobial peptide (CM11) on Blastocystis sp

Blastocystis infection accounts for one of the causes of gastrointestinal problems with the prevalence rate of 3-100% worldwide. There is a wide range of drugs examined for the treatment of infected patients, among them metronidazole (MTZ) has been introduced as one of the efficient drugs. Besides to the suitable clinical effects, the administration of MTZ has some reported side-effects which emphasize on the identification of putative alternates. To this end, we aimed to evaluate the cytotoxicity effect of a newly-introduced synthetic antimicrobial peptide (AMP) named CM11 on in vitro cultured Blastocystis. Our results exhibited that CM11 treatment affected the viability of parasites in two cultural conditions including culturing alone and in co-culture with the Caco-2 cell line. The time- and dose-dependent effect of CM11 was consistent with the effect of MTZ which was used as control positive. The highest toxicity effect of CM11 was observed at the concentration of 24 μg/ml, leading to 28.7% and 25% viable parasites after 24 h and 48 h incubation times, respectively. Interestingly, the disruption of the Blastocystis cell membrane could be observed in the treated parasites. Therefore, CM11 can be suggested as a potential treatment for Blastocystis-infected patients after further in vitro and in vivo assessments.

Parasitic infections represent a significant health threat among recent immigrants in Chicago

Parasitic infections are likely under-recognized among immigrant populations in the USA. We conducted a cross-sectional study to evaluate if such infections have health impacts among recent immigrants in Chicago and to identify predictive factors for parasitic infections. A total of 133 recent immigrants were enrolled, filling out a standardized medical questionnaire and providing blood and stool samples. Appriximately 12% of subjects (15/125) who provided a blood or stool sample for testing were found to have evidence of current or prior infection with a pathogenic parasite, of which Toxocara spp. (8 subjects, 6.4%) and Strongyloides stercoralis (5 subjects, 4%) were most commonly identified. Parasitic infection was more likely among subjects who had immigrated within the previous 2 years and those with a self-reported history of worms in the stool. The most useful surrogate markers identified for parasitic infections were an elevated immunoglobulin E level (seen in 46.7% (7/15) of subjects with parasitic infections and 20% (22/110) of uninfected individuals, p = 0.04) and the presence of Blastocystis hominis cysts on Ova & Parasite exam (detected in 38.5% (5/13) of subjects with parasitic infections who provided a stool sample and 5.1% (5/98) of uninfected subjects, p = 0.002). Our study found that parasitic infections may be common in recent US immigrants, which highlights an important health disparity among a vulnerable population that merits further study. Additionally, clinical risk factors, symptoms, and laboratory findings traditionally thought to be associated with parasites were commonly found but not predictive of infection in this study population.

A Review of Quercus infectoria (Olivier) Galls as a Resource for Anti-parasitic Agents: In Vitro and In Vivo Studies

Parasitic diseases represent one of the causes for significant global economic, environmental and public health impacts. The efficacy of currently available anti-parasitic drugs has been threatened by the emergence of single drug- or multidrug-resistant parasite populations, vector threats and high cost of drug development. Therefore, the discovery of more potent anti-parasitic drugs coming from medicinal plants such as Quercus infectoria is seen as a major approach to tackle the problem. A systematic review was conducted to assess the efficacy of Q. infectoria in treating parasitic diseases both in vitro and in vivo due to the lack of such reviews on the anti-parasitic activities of this plant. This review consisted of intensive searches from three databases including PubMed, Science Direct and Scopus. Articles were selected throughout the years, limited to English language and fully documented. A total of 454 potential articles were identified, but only four articles were accepted to be evaluated based on inclusion and exclusion criteria. Although there were insufficient pieces of evidence to account for the efficacy of Q. infectoria against the parasites, this plant appears to have anti-leishmanial, anti-blastocystis and anti-amoebic activities. More studies in vitro and in vivo are warranted to further validate the anti-parasitic efficacy of Q. infectoria.

Parasitic Infections of the Stem Cell Transplant Recipient and the Hematologic Malignancy Patient, Including Toxoplasmosis and Strongyloidiasis

Hematopoietic stem cell transplantation (HSCT) recipients may infrequently develop parasitic infections at the time of the procedure via contamination from allograft tissue or blood products, and in the post-transplantation period through the traditional route of infection or as a reactivation caused by immunosuppression related to the transplant. To reduce risk, efforts should be directed at performing a comprehensive history, maintaining a high index of suspicion, and adhering to preventive measures. Additional strategies for the prevention, screening and careful follow-up, identification, and pre-emptive treatment of parasitic infections are required to reduce morbidity and mortality in HSCT patients.

Development and evaluation of high-resolution melting curve analysis for rapid detection and subtyping of Blastocystis and comparison the results with sequencing

Blastocystis is a prevalent parasite that has a wide distribution. In order to design HRM real-time PCR, primers were selected from SSU rRNA gene to amplify specific fragment with different melting temperatures for each subtype of Blastocystis. Subsequently, HRM real-time PCR was performed and melting curve analysis was done by Rotor-Gene Q software. The results of HRM real-time PCR was then compared with sequence results of "barcoding region" of SSU rRNA gene of Blastocystis. To evaluate sensitivity of test, 10-fold serial dilutions of the parasite were prepared from ~ 10⁶ to 1 parasite per mL of stool sample and were investigated by HRM real-time PCR. In order to determine specificity of method, HRM real-time PCR was done for some microorganisms and Blastocystis-negative stool samples. In silico analysis showed that all seventeen subtypes of Blastocystis were distinguish. In vitro analysis revealed that the test discriminated subtypes with specific melting temperatures.

Lower prevalence of Blastocystis sp. infections in HIV positive compared to HIV negative adults in Ghana

Background

Sub-Saharan Africa is endemic for intestinal parasites and distinguished for the largest burden of HIV cases. Blastocystis sp. is one of the most common protists infecting humans but its role in human disease is still controversial. Aim of this study was to investigate the prevalence of Blastocystis sp. in HIV positive and negative adults in Ghana and its association with immune status and other risk factors.

Methods

122 HIV positive outpatients and 70 HIV negative blood donors from the Komfo Anokye Teaching Hospital in Kumasi, Ghana, were included in the present study. Demographic, clinical and laboratory data were collected and HIV positive patients distinguished for CD4+ T cell count <200 cells/μl (n = 54) and >200 cells/μl (n = 68). A Blastocystis’s phylogenetic analysis was performed to determine sample subtype (ST).

Results

The prevalence of Blastocystis sp. in adult HIV positive individuals was lower than in HIV negative persons (6.6% vs. 20.0%, p = 0.008) and Blastocystis sp. ST1 was the most prevalent strain. Within HIV positive participants, the prevalence of Blastocystis sp. was lower in those individuals with CD4+ T cell count <200 cells/μl than in patients with higher CD4+ T cell count (1.9% vs. 10.3%, p = 0.076). Multiple regression analysis revealed that Blastocystis sp. was inversely associated with an obese Body Mass Index (BMI) in HIV negative persons (p = 0.040). Presence of Blastocystis sp. was correlated with higher CD4+ T cell count in HIV positive participants (p = 0.049).

Conclusion

It is largely reported that people living with HIV (PLHIV) in Africa are affected from parasite infections and that co-infections may adversely impact on their immune status, accelerating progress to AIDS and worsening gastrointestinal manifestations. Differently, in this study Blastocystis sp. was associated with a better immune status jointly with a healthy body weight while it seems to be reduced with the progression of HIV infection. This data agree with recent suggestions that Blastocystis sp. can represent a component of the healthy gut microbiota.

Does Irritable Bowel Syndrome Exist? Identifiable and Treatable Causes of Associated Symptoms Suggest It May Not

Significant shortcomings in irritable bowel syndrome (IBS) diagnosis and treatment may arise from IBS being an “umbrella” diagnosis that clusters several underlying identifiable and treatable causes for the same symptom presentation into one classification. This view is compatible with the emerging understanding that the pathophysiology of IBS is heterogeneous with varied disease mechanisms responsible for the central pathological features. Collectively, these converging views of the pathophysiology, assessment and management of IBS render the traditional diagnosis and treatment of IBS less relevant; in fact, they suggest that IBS is not a disease entity per se and posit the question “does IBS exist?” The aim of this narrative review is to explore identifiable and treatable causes of digestive symptoms, including lifestyle, environmental and nutritional factors, as well as underlying functional imbalances, that may be misinterpreted as being IBS.

Population-level analysis of Blastocystis subtype prevalence and variation in the human gut microbiota

OBJECTIVE

Human gut microbiome studies are mainly bacteria- and archaea-oriented, overlooking the presence of single-cell eukaryotes such as Blastocystis, an enteric stramenopiles with worldwide distribution. Here, we surveyed the prevalence and subtype variation of Blastocystis in faecal samples collected as part of the Flemish Gut Flora Project (FGFP), a Western population cohort. We assessed potential links between Blastocystis subtypes and identified microbiota-host covariates and quantified microbiota differentiation relative to subtype abundances.

DESIGN

We profiled stool samples from 616 healthy individuals from the FGFP cohort as well as 107 patients with IBD using amplicon sequencing targeting the V4 variable region of the 16S rRNA and 18S rRNA genes. We evaluated associations of Blastocystis, and their subtypes, with host parameters, diversity and composition of bacterial and archaeal communities.

RESULTS

Blastocystis prevalence in the non-clinical population cohort was 30% compared with 4% among Flemish patients with IBD. Within the FGFP cohort, out of 69 previously identified gut microbiota covariates, only age was associated with Blastocystis subtype carrier status. In contrast, a strong association between microbiota community composition and Blastocystis subtypes was observed, with effect sizes larger than that of host covariates. Microbial richness and diversity were linked to both Blastocystis prevalence and subtype variation. All Blastocystis subtypes detected in this cohort were found to be less prevalent in Bacteroides enterotyped samples. Interestingly, Blastocystis subtypes 3 and 4 were inversely correlated with Akkermansia, suggesting differential associations of subtypes with host health.

CONCLUSIONS

These results emphasise the role of Blastocystis as a common constituent of the healthy gut microbiota. We show its prevalence is reduced in patients with active IBD and demonstrate that subtype characterisation is essential for assessing the relationship between Blastocystis, microbiota profile and host health. These findings have direct clinical applications, especially in donor selection for faecal transplantation.

Comparison and Recommendations for Use of Dientamoeba fragilis Real-Time PCR Assays

Dientamoeba fragilis is a gastrointestinal trichomonad parasite whose pathogenicity is yet to be determined. The difficulty involved in microscopically diagnosing D. fragilis in feces led to the development of real-time PCR methodologies for the detection of D. fragilis in stool samples. Prevalence studies in Europe show much higher levels of infection where a laboratory-developed real-time assay is the predominant assay for the detection of Dientamoeba fragilis than in regions that use the EasyScreen assay for detection of gastrointestinal pathogens. The aim of this study was to compare a commercially available Dientamoeba fragilis assay (Genetic Signatures EasyScreen assay) to a widely used laboratory-developed real-time PCR method. Two hundred fifty fecal samples were screened using the laboratory-developed real-time assay on four real-time PCR platforms producing a number of discrepant results. Limit-of-detection studies were undertaken to attempt to resolve sensitivity for each platform tested. The presence or absence of Dientamoeba fragilis DNA in discrepant samples was shown using PCR amplicon next-generation sequencing. Eukaryotic 18S diversity profiling was conducted on discrepant samples to identify the presence or absence of additional protozoan species in samples that may be responsible for cross-reactivity seen in these samples. The results revealed the potential for multiple false-positive results when using the laboratory-developed real-time assay across multiple real-time platforms using manufacturer default settings. This report provides recommendations to resolve these issues where possible and suggestions for future prevalence studies, and it emphasizes the EasyScreen assay as the molecular method of choice as well as the need for standardization of detection assays across all nations screening for D. fragilis.

Resistance towards metronidazole in Blastocystis sp.: A pathogenic consequence

Blastocsytis sp. is a protozoan parasite that has been linked to common gastrointestinal illnesses. Metronidazole, the first line therapy, was reported to show frequent inefficacy. Previously, Blastocystis sp. isolated from different population showed varying metronidazole resistance. However, the effect of metronidazole treatment on pathogenic potentials of Blastocystis sp. isolated from different populations, which is known to have different gut environment, is unclear. This study investigates the in vitro effect of metronidazole on the pathogenic potentials of Blastocystis sp. isolated from urban and orang asli individuals. Blastocystis sp. ST 3 isolated from symptomatic and asymptomatic individuals were treated with a range of metronidazole concentration. The parasites’ growth characteristics, apoptotic rate, specific protease activity and the ability to proliferate cancer cells were analyzed upon treatment with 0.001 mg/l metronidazole. The study demonstrates that Blastocystis sp. isolates showed increase in the parasite numbers especially the amoebic forms (only in urban isolates) after treating with metronidazole at the concentration of 0.001 mg/ml. High number of cells in post-treated isolates coincided with increase of apoptosis. There was a significant increase in cysteine protease of Blastocystis sp. isolates upon treatment despite the initial predominance of serine protease in asymptomatic isolates. Metronidazole resistant Blastocystis sp. also showed significant increase in cancer cell proliferation. Resistance to metronidazole did not show significant different influence on the pathogenicity between Blastocystis sp. isolated from urban and orang asli individual. However, an increase in parasite numbers, higher amoebic forms, cysteine protease and ability to proliferate cancer cells implicates a pathogenic role. The study provides evidence for the first time, the effect of metronidazole towards enhancing pathogenic potentials in Blastocystis sp. when isolated from different gut environment. This necessitates the need for reassessment of metronidazole treatment modalities.

BLASTOCYSTIS AND OTHER INTESTINAL PARASITES INFECTIONS IN ELEMENTARY SCHOOL CHILDREN IN DUKUH VILLAGE, KARANGASEM DISTRICT, BALI

Blastocystis spp. is the most common enteric parasitic infection found in several community surveys from developing countries. Blastocystis infections may cause gastrointestinal symptoms, but also cause extraintestinal symptoms such as urticaria and joint pain. Blastocystis infection can also be asymptomatic or a carrier. However, the prevalence of Blastocystis infection in children has not yet been fully investigated in Indonesia, particularly in Bali Province. This study aimed to determine the prevalence of Blastocystis and other intestinal parasites in elementary school children stools in Dukuh village, Karangasem regency. A cross sectional study was conducted in September 2016. A total of 103 school children stools were collected by informed consent and parasites were examined by microscopy with wet mounts method using Lugol’s iodine solution. Thirty-five school children were infected with Blastocystis spp. (35/103, 34%) that consisted of a single infection (29/35, 82.9%) and mix infection with other parasites (6/35, 17.1%). The mix infections were Blastocystis spp. and hookworm infection (1/6, 16.7%), Blastocystis spp. and Entamoeba coli (1/6, 16.7%), Blastocystis spp. and Giardia lamblia (2/6, 33.3%), Blastocystis spp. and Entamoeba histolytica/ Entamoeba dispar (1/6, 16.7%) and Blastocystis spp. and Entamoeba histolytica/ Entamoeba dispar and Giardia lamblia (1/6, 16.7%). The vacuolar forms of Blastocystis were dominantly found, in which was non-infectious form, whereas the infectious form is the cyst form and Blastocystis density was observed less than 5 cells per field of view at 400 magnification in all cases. This study concluded that the high prevalence of Blastocystis infection in elementary school children in Dukuh Village, Karangasem District, Bali that were dominantly single infections and several mix infections with other intestinal parasites. The high prevalence of Blastocystis infection in elementary school children suggested that it needs proper prevention measures for the children in this study area.

Blastocystis Hominis and Chronic Abdominal Pain in Children: Is there an Association between Them?

Chronic abdominal pain has many etiologies, one of them being parasites. The aim of this study was to find an association between chronic abdominal pain in children and Blastocystis hominis (Bh). Clinical files of patients with Bh and functional abdominal pain were reviewed. A comparison was made between patients who showed an improvement of their symptoms and those who did not. Out of the 138 patients who had functional abdominal pain and Bh, 37 patients did not receive any treatment (26.8%), while 101 received it and were treated with different antimicrobial agents (73.2%); regarding the improvement of symptoms, a statistically significant difference (p < 0.001) was observed. Chronic abdominal pain in children has different etiologies; however, we have documented through this work that it is appropriate to provide antimicrobial treatment for patients with Bh and chronic abdominal pain.

Viability Screen of LOPAC1280 Reveals Phosphorylation Inhibitor Auranofin as a Potent Inhibitor of Blastocystis Subtype 1, 4, and 7 Isolates

Blastocystis is an enteric parasite with extensive global prevalence. Studies have linked infection with this protist with a variety of gastrointestinal disorders, including irritable bowel syndrome. Due to the polymorphic nature of Blastocystis, studies on the parasite could be complicated, as results can be easily misinterpreted. Metronidazole is the commonly prescribed drug for Blastocystis infection, although there have been increasing reports of drug resistance. Hence, there is a need to identify alternative drugs to eliminate Blastocystis infection. In this study, LOPAC¹²⁸⁰ was screened and drugs that can decrease the viability of three Blastocystis isolates in cultures were identified. Using apoptosis assay and imaging flow cytometry, phenotypic changes in Blastocystis cells after treatment were also analyzed to obtain insights into the possible mechanism of action of these drugs. Three drugs-diphenyleneiodonium chloride, auranofin, and BIX 01294 trihydrochloride hydrate-were effective against all three isolates tested. Repurposing of these drugs for Blastocystis treatment could be a way of combating metronidazole resistance relatively quickly and at a lower cost.

Exacerbated symptoms in Blastocystis sp.-infected patients treated with metronidazole: two case studies

Blastocystis sp. is a gastrointestinal (GI) protozoan parasite reported to cause non-specific GI symptoms including diarrhea, flatulence, abdominal pain, and nausea. Complete eradication of Blastocystis sp. is rather challenging even with the drug of choice, i.e., metronidazole. Here, we report on two Blastocystis sp.-infected individuals, who presented increased parasite load and exacerbated symptoms upon treatment with the usual recommended dosage and regime of metronidazole. The two studies uniquely demonstrate for the first time a cyst count as high as fivefold more than the original cyst count before treatment and show an exacerbation of GI symptoms despite treatment. The study provides additional support in recognizing metronidazole resistance in Blastocystis sp. and its consequences towards the pathogenicity of the parasite.

Beyond O&P Times Three

Although examination of the stool for ova and parasites times three (O&P ×3) is routinely performed in the United States (US) for the evaluation of persistent and/or chronic diarrhea, the result is almost always negative. This has contributed to the perception that parasitic diseases are nearly non-existent in the country unless there is a history of travel to an endemic area. The increasing number of immigrants from third-world countries, tourists, and students who present with symptoms of parasitic diseases are often misdiagnosed as having irritable bowel syndrome or inflammatory bowel disease. The consequences of such misdiagnosis need no explanation. However, certain parasitic diseases are endemic to the US and other developed nations and affect both immunocompetent and immunocompromised patients. Testing for parasitic diseases either with O&P or with other diagnostic tests, followed by the recommended treatment, is quite rewarding when appropriate. Most parasitic diseases are easily treatable and should not be confused with other chronic gastrointestinal (GI) disorders. In this review, we critically evaluate the symptomatology of luminal parasitic diseases, their differential diagnoses, appropriate diagnostic tests, and management.

Blastocystis subtypes and their association with Irritable Bowel Syndrome

Blastocystis spp. is a common intestinal protozoan that affects humans and animals. The role of this parasite as a pathogen is still controversial and it is suspected to be linked to Irritable Bowel Syndrome (IBS), a functional bowel disorder characterized by chronic or recurrent abdominal pain associated with altered intestinal habits. A broad search in electronic databases, libraries, portals of journals, etc. for reports on the association between the parasite and IBS without language restriction was performed. The selection was not restricted by date, but articles published in the last seven years were given preference. We investigated the evidence regarding Blastocystis and IBS coexistence as well as the implications of the parasite in pathogenesis and clinical manifestations. Only standardized parasitological tools, supplemented by epidemiological analysis, will be able to clarify whether parasite carriage could be connected to IBS and its status as a human pathogen. Although a variation in pathogenicity and virulence between subtypes has been confirmed, Blastocystis can only be considered an indicator of dysbiosis. Accurate diagnoses of this parasitic eukaryote, specifically at genotypic and phenotypic levels, as well as the complete analysis of the intestinal microbial communities, have to be included in the protocol of those patients with IBS.

An alternative DNA extraction method for detection of Blastocystis spp. in human fecal samples

Polymerase chain reaction (PCR) is an effective technique for diagnosis of Blastocystis infection. Notably, DNA isolation procedure is extremely critical for the PCR step. In the present study, a recently described extraction procedure, named as the "sand method" was modified and adapted for isolation of Blastocystis DNA. To evaluate its efficacy, the current method and QIAamp DNA Stool Mini Kit (Qiagen) were applied to fresh human stool samples. Our results indicated that, the mean DNA concentrations obtained by the sand method and the commercial kit were 48 and 55 ng/μl, respectively. Also, no DNA inhibitors were detected in two methods. The sand method was capable of detecting 16 parasites per 50 mg feces. DNA samples extracted by both methods were subjected to PCR. Blastocystis spp. were detected in 11 (31.4%) of 35 samples, and perfect agreement (κ: 1.000) was found between the PCR-sand method and PCR-commercial kit method. The samples that were detected positive by PCR-sand method were successfully sequenced, and Blastocystis subtypes (STs) were identified as ST3, ST2 and ST1. In conclusion, the present study indicates that the sand method provides a simple, rapid and inexpensive procedure for reliable extraction of Blastocystis DNA from stool samples.

Temporal trends of intestinal parasites in patients attending a tertiary care hospital in south India: A seven-year retrospective analysis

BACKGROUND & OBJECTIVES

Intestinal parasitic infections and their associated complications are a major cause of morbidity in the developing world. This retrospective study was done to assess the prevalence of intestinal parasitic infections among patients in a tertiary healthcare setting and to analyze age-, gender- and time-related trends in the prevalence of these intestinal parasites over a seven year period (2006-2012).

METHODS

The presence of various intestinal parasites in a tertiary care setting over a seven year period in different age groups was determined by performing routine stool microscopy. Modified acid-fast staining was performed for stool samples collected from children less than five years of age for the detection of intestinal coccidian parasites. Statistical analysis was carried out to analyze age-related trends in relation to the prevalence of commonly detected intestinal parasites. Seasonal fluctuations in parasite prevalence were evaluated by performing harmonic regression analysis.

RESULTS

A total of 257,588 stool samples were received over the seven year period for examination. The highest percentage of intestinal parasites was in the 6-10 yr age group. Among the intestinal parasites, Giardia intestinalis had the highest prevalence across most age groups, except in those above 60 yr of age where hookworm became more prevalent. A significant decreasing trend with age was observed for G. intestinalis, whereas for hookworm and Strongyloides stercoralis, an increasing trend with age was seen. Significant linear temporal trends were observed for parasites such as G. intestinalis, Entamoeba histolytica and Ascaris lumbricoides.

INTERPRETATION & CONCLUSIONS

While G. intestinalis was more common in the younger age groups, certain soil-transmitted helminths such as hookworm and S. stercoralis showed a higher prevalence in the older populations. Significant temporal trends and seasonality were observed for some of the common intestinal parasites.