Escasa eficacia de metronidazol en la erradicación de Blastocystis hominis en pacientes sintomáticos: serie de casos y revisión sistemática de la literatura

The Role of Blastocystis spp. in the Etiology of Gastrointestinal and Autoimmune Diseases

Blastocystis spp. has been linked to gastrointestinal symptoms, yet its pathogenicity remains uncertain. In addition, the roles of virulence factors, pathogenic potential, and host-specific traits associated with symptomatic infections are still not well understood. The growing number of immunocompromised patients has contributed to an increasing prevalence of Blastocystis spp. infections, which may be implicated in the development of various inflammatory diseases, including irritable bowel syndrome (IBS), colorectal cancer, and autoimmune disorders such as Hashimoto's disease and ulcerative colitis. However, the presence of nonspecific symptoms often complicates diagnosis. This study aimed to present current data on the impact of Blastocystis spp. on the development and progression of gastrointestinal and autoimmune diseases, as well as to explore potential treatment options for Blastocystis spp. infections. A literature review was conducted to analyze the role of Blastocystis spp. in the pathogenesis of specific diseases and to investigate potential mechanisms of its interaction with the host organism. Advances in diagnostic techniques, particularly PCR, allow not only for the detection of Blastocystis spp. but also for the identification of specific subtypes, improving treatment precision. Beyond conventional therapies like metronidazole, there is a growing emphasis on alternative treatments, including the use of medicinal plants and probiotics.

Assessment of Lactobacillus acidophilus (L. acidophilus) therapeutic and prophylactic role in rats experimentally infected with Blastocystis subtype 3 (ST3)

Blastocystis, an eukaryote, inhabits the intestinal tract of humans and animals worldwide. Lactobacillus acidophilus (L. acidophilus), a probiotic, has been reported to be effective against blastocystosis. The present study evaluated the therapeutic and prophylactic effectiveness of L. acidophilus compared to metronidazole (MTZ) in rats experimentally infected with Blastocystis subtype 3 (ST3). Four groups of Blastocystis ST3-infected rats received MTZ, L. acidophilus, both MTZ and L. acidophilus, or prophylactic L. acidophilus. Non-infected and infected control groups were included. The effectiveness of treatment and prevention was evaluated using parasitological monitoring, histopathological examination, immunohistochemical staining for TNF-α and IgA expression, and immunological testing for TNF-α and IL-10. In the L. acidophilus-treated group, a 76% reduction in the mean fecal parasitic count and a 67% clearance in the intestinal wash were achieved aligning closely with outcomes observed in the MTZ-treated group. An immunomodulatory impact via upregulation of the anti-inflammatory cytokine IL-10 and downregulation of the pro-inflammatory cytokine TNF-α was demonstrated as well. Combined administration of MTZ and L. acidophilus exhibited superior efficacy with a 99% decrease in the mean fecal parasitic count and a 98% decrease in the intestinal fluid parasitic count. Additionally, the lowest TNF-α and the highest IL-10 serum levels. Prophylactic use of L. acidophilus for 7 days neither prevented infection nor reduced its severity. Furthermore, no significant differences were detected in serum levels of TNF-α and IL-10 following post-prophylaxis and post-treatment with L. acidophilus. Accordingly, L. acidophilus might be recommended as an adjuvant treatment alongside MTZ for improved efficacy against blastocystosis.

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.

Should we treat Blastocystis sp.? A double-blind placebo-controlled randomized pilot trial

BACKGROUND

Blastocystis sp. is a worldwide-distributed protist colonizing the guts of humans and a great variety of animals. It is unclear whether it is just a commensal or an infectious parasite that prompts eradication.The main objective of this study was to evaluate the usefulness of metronidazole in patients with gastrointestinal symptoms harbouring only Blastocystis sp. In addition, we explored whether Blastocystis subtype or concomitant parasitic infection detected by polymerase chain reaction (PCR) may influence treatment outcome.

METHODS

We included adults with persistent gastrointestinal symptoms (>14 days) visiting a primary care physician and in whom stool microscopy revealed only Blastocystis sp. Eligible patients were randomized to receive 10 days of metronidazole or placebo, followed by a crossover if still symptomatic. The primary outcome was normal stool consistency. Secondary outcomes were the changes in other abdominal symptoms (bloating, flatulence, abdominal pain, number of daily bowel movements) and general wellbeing. After the clinical phase of the study, Blastocystis subtypes were determined by PCR sequencing and stool samples were tested for 11 other protozoa with an in-house PCR.

RESULTS

We screened 581 outpatients for inclusion, of which 50 met the eligibility criteria. There was no difference in the primary outcome, nor any of the secondary outcomes between the subjects treated with metronidazole and placebo.The most frequent Blastocystis subtypes were ST4 (11/36) and ST2 (10/36). The in-house PCR was positive for other protozoa in 25% (10/40) of the patients. We identified Dientamoeba fragilis in 5, Entamoeba dispar in 3 and Cyclospora cayetanensis in 2 patients. Stratified analysis according to Blastocystis subtype or the presence of other protozoa showed no significant difference in treatment outcome with metronidazole or placebo.

CONCLUSIONS

Among patients infected with Blastocystis sp., metronidazole, compared with placebo, was not better in improving gastrointestinal symptoms, irrespective of subtype or microscopically undetected coinfection with other protozoa.

Anti-blastocystosis activity of antioxidant coated ZIF-8 combined with mesoporous silicas MCM-41 and KIT-6

The biocompatible hybrid Zeolitic imidazolate framework-8 (ZIF-8)/structured silica nanocomposite can be loaded with antioxidants such as curcumin and resveratrol to offer multiple advantages of drug functionalization and structural stability. blastocystosis, an enteric parasite, has various outcomes and its treatment includes drugs which have side effects and do not result in a full cure. We aimed to design novel biocompatible nanocomposites containing natural antioxidant, resveratrol or curcumin and ZIF-8/mesoporous silica. We also assessed their anti-blastocystosis activities as bioactive novel nanocomposites. The nano-silica (MCM-41 and KIT-6) was synthesized using a hydrothermal technique and made composite with ZIF-8 using an ultrasonic technique. The antioxidants, curcumin and resveratrol, were loaded over ZIF-8/MCM-41 and ZIF-8/KIT-6 using a rotary evaporator technique to form novel nanocomposites with bioactive properties. The formulated nanocomposites were characterized. To test their biological activity, suspension of cultured blastocystosis cysts (subtype 3) were exposed to increasing concentrations of nanocomposites and the minimal lethal concentration of each nanocomposite was calculated. The bioactive nanocomposites (ZIF-8/KIT-6, ZIF-8/KIT-6/Resveratrol and ZIF-8/MCM-41/Curcumin) were formulated. Anti-blastocystosis activity of the tested nanocomposites was both dose and time dependent. ZIF-8/KIT-6/Resveratol showed the maximum percentage of growth inhibition (~ 100%) at a concentration of 500 µg/ml after 5 h of exposure. More than 90% of blastocystosis cysts’ growth was significantly inhibited at all concentrations of ZIF-8/MCM-41/Curcumin, with different times of exposure, while it occurred only at the highest concentration of ZIF-8/KIT-6 (800 µg/ml). Using cheap, simple, reproducible and scalable techniques, we nano-formulated innovative bioactive nanocomposites, by incorporating the bioactive ZIF-8 (Zn²⁺ with imidazole), structured mesosilica and natural antioxidant compounds, curcumin or resveratrol, to generate multifunctional modalities. These eco-friendly, naturally based, safe, economical, biocompatible, and bioavailable nanocomposites are potential nanotherapeutics. The anti-blastocystosis results of these three nanocomposites indicate their potentially promising innovative and safe use as alternative Blastocystosis therapies.

Prevalence and impact of antimicrobial resistance in gastrointestinal infections: A review

Antimicrobial resistance has become a worldwide problem due to its excessive increase in recent years. The aim of the present review was to bring together data from different articles describing the levels of antimicrobial resistance in the most common gastrointestinal infections reported across the globe. The literature search was carried out in Google Scholar, Medline, Embase, and Pubmed, with the terms "antimicrobial resistance", "resistance in gastrointestinal disorders", and "resistance in amoebiasis", in Spanish and English. Mexican treatment guidelines and consensuses from 2017 to the present were utilized. Publications from the last ten years were chosen to describe the level of resistance. They had adequate sample sizes, the Material and Methods sections were precise, and they included multicenter studies, national and international consensuses, meta-analyses, systematic reviews, and extensive texts. The final number of articles was 51. The microorganisms that demonstrated the highest percentage of resistance were Helicobacter pylori (metronidazole 50%-80%, clarithromycin 20%-40%, and levofloxacin 30%-35%), Clostridioides difficile (clindamycin 8.3%-100%, cephalosporines 51%), Campylobacter jejuni and Campylobacter coli (fluoroquinolones 85%), Escherichia coli (ampicillin 76.5%), Entamoeba histolytica (metronidazole 50%), and bacterial peritonitis (third-generation cephalosporines 40%, methicillin 85%). Antimicrobial resistance is reaching elevated percentages, making it necessary to evaluate the situation of each patient, to successfully treat gastrointestinal infections.

Blastocystis in domesticated and wild mammals and birds

Blastocystis is a ubiquitous parasite that infects a broad range of vertebrate hosts including humans and domestic and wild animals. While human infections have been occasionally associated with gastrointestinal illnesses and/or urticaria, animal infections are not usually associated with disease. However, from a public health perspective, most subtypes isolated in humans have also been isolated from animals raising the question of the importance of animal reservoirs in the epidemiology of this parasite. The identification of Blastocystis in water supplies suggests water can be a potential vehicle in the transmission of this parasite not only for humans but also for animals. In addition, Blastocystis has been detected in retail fresh produce. Knowledge of this parasite has greatly expanded in the last two decades from simple microscopic observations to the application of molecular tools to explore Blastocystis taxonomy and epidemiology. This review provides a comprehensive overview of Blastocystis in animals highlighting the subtype diversity of this widespread and genetically diverse parasite in different animal groups. This information will be useful in understanding the current status of taxonomy, epidemiology, zoonotic potential, and public health importance of Blastocystis.

Evaluation of the effect of 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol in comparison with metronidazole in an in vitro culture of Blastocystis in samples of patients with irritable bowel syndrome

Metronidazole is the most-used pharmaceutical for the treatment of infection by Blastocystis. However, studies have reported resistance of the microorganism towards this pharmaceutical. In Mexico, studies concerning the prevalence of this parasite and its relationship to Irritable Bowel Syndrome have been carried out. To evaluate the in vitro effect of metronidazole and the compound 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol over Blastocystis, as well as the prevalence of Blastocystis in patients with Irritable Bowel Syndrome. A prospective, transversal design study (April 2016-April 2017) of 51 samples of patients with Irritable Bowel Syndrome, obtained from the ISSEMyM Medical Center in Toluca, Mexico. For the identification of Blastocystis was done in three serial stool samples through direct microscopic examination and the Ritchie technique. The in vitro susceptibility test towards metronidazole and the triazolic compound was done through a microculture in concentrations of 1 to 1000 µg/mL, each one in triplicate. A 31.3% prevalence of Blastocystis was observed in the population, with greater prevalence in women (30.2%) than in men (25%). In the susceptibility test, a CL50 of 64 µg/mL was obtained for metronidazole, in comparison to the CL50 of 250 µg/mL for 1,3-bis-(4-phenyl-[1,2,3] triazole-1-il)2-propanol. This molecule in development has an effect for the treatment of infection by Blastocystis in vitro in patients with IBS and therefore, more studies should be performed.

The influence of probiotic bacteria and human gut microorganisms causing opportunistic infections on Blastocystis ST3

BACKGROUND

Blastocystis subtype 3 is an intestinal protist present in humans throughout the world with a controversial pathogenic potential. It has been suggested that probiotic bacteria inhibit the multiplication of gut protozoans, while others are beneficial for their development. This study aimed to evaluate the efficacy of the lactic acid bacteria Lactobacillus rhamnosus, Lactococcus lactis and Enterococcus faecium in Blastocystis ST3 eradication and the relevance of the intestinal microorganisms Escherichia coli, Candida albicans and Candida glabrata in protozoan proliferation. Blastocystis xenic and axenic culture was co-incubated with the above-mentioned microorganisms and their cell free supernatants at different concentrations in vitro. The number of protozoan cells was counted every day.

RESULTS

Both experiments, with xenic and axenic cultures, showed Blastocystis inhibition by L. rhamnosus and L. lactis and their supernatants from the 2nd day of co-incubation. Furthermore, co-incubation with both E. faecium and E. coli showed a beneficial influence on Blastocystis during the first 2 days. Only after 3 days did the above-mentioned bacteria start to inhibit Blastocystis growth in both cultures. The supernatant containing the metabolites of E. coli was effective to a lesser degree. Compared to the control samples, co-incubation with both C. albicans and C. glabrata showed a faster decrease in Blastocystis proliferation, but this was not statistically significant.

CONCLUSIONS

This study has shown the potential of using L. rhamnosus and L. lactis, as well as E. faecium as a prophylactic treatment against Blastocystis colonization or as an additional treatment regimen in combination with standard drugs.