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.

Medicinal Plants as Natural Anti-Parasitic Agents Against Blastocystis Species.

BACKGROUND: Blastocystis species (sp.) are enteric parasites that live in both humans' and animals' gastrointestinal tracts. Blastocystis hominis (B. hominis) is the recognizable human isolates in clinical and diagnostic specimens. Human infection occurs via the oro-fecal route, particularly in developing areas due to the lack of sanitation and hygienic facilities. B. hominis can exist in the large intestine for weeks to years until treated appropriately. Metronidazole is the drug of choice for the treatment of Blastocystis infection. However, it induces intolerable side effects and has been shown to have teratogenic and carcinogenic potential. Several medicinal plant extracts have been experimentally tested against Blastocystis infection in comparison to currently available treatments. OBJECTIVE: Based on in vitro and in vivo studies, this article reviewed anti-Blastocystis activity of some medicinal plants. METHODS: To conduct the research for this review, Google Scholar and PubMed were the primary search engines used to find relevant literature. A total of 19 published in vitro and in vivo studies were evaluated to identify the anti-Blastocystis effects of various medicinal plants. RESULTS: Multiplication of Blastocystis parasites as well as nucleic acids and protein synthesis, all be inhibited by extracts from different medicinal plants. These natural agents have been shown to be both safe and effective when compared to the existing treatment options. CONCLUSION: Different medicinal plants can combat Blastocystis infection and could be a good substitute for metronidazole and other synthetic treatments.

Molecular investigation of Blastocystis sp. and its subtypes in cancer patients under chemotherapy in Aegean region, Turkey.

Blastocystis sp. is a common enteric protist found in humans and many other animals. Although the clinical relevance of Blastocystis sp. is currently fully unknown for humans, the prevalence of Blastocystis and subtypes are investigated in immunocompetent individuals presenting with symptoms like diarrhea or immunocompromised individuals including cancer patients. In this comprehensive study, the prevalence of Blastocystis sp. and subtypes were investigated in patients (n=94) with different types of malignant solid tumors using PCR targeting SSU rDNA gene and sequencing. All patients were undergoing chemotherapy and had diarrhea. According to obtained results, 46 patients were found to be Blastocystis positive and the molecular prevalence was detected as 48.9%. Among the positive specimens, 43 (43/46; 93.5%) of them were successfully subtyped. ST4 was the most predominant subtype and detected in 24 (55.8%) patients, followed by ST1 (11 patients, 25.6%) and ST3 (8 patients, 18.6%). In the colon cancer group, which had the highest number of patients, Blastocystis sp. was detected with a higher prevalence rate of 61.5% compared with the prevalence rate (48.9%) of all patients. Interestingly, ST3 was not detected in any of this patient group in contrast to ST4 and ST1. In conclusion, high prevalence of the Blastocystis in the immunocompromised patient groups shows the susceptibility of this patient group against any other infectious agents.

Collateral Damage in the Human Gut Microbiome - Blastocystis Is Significantly Less Prevalent in an Antibiotic-Treated Adult Population Compared to Non-Antibiotic Treated Controls.

Antibiotics can drive the rapid loss of non-target, phylogenetically diverse microorganisms that inhabit the human gut. This so-called "collateral damage" has myriad consequences for host health and antibiotic mediated changes to the gut microbiota have been implicated in the aetiology of many chronic diseases. To date, studies have largely focused on how antibiotics affect the bacterial fraction of the gut microbiome and their impact on non-bacterial members, including prevalent eukaryal species, such as Blastocystis, remains largely unknown. Here we assessed the prevalence and diversity of Blastocystis in an elderly adult group that were in receipt of antibiotics (n = 86) and an equivalent non-antibiotic treated group (n = 88) using a PCR-based approach. This analysis revealed that although similar subtypes were present in both groups, Blastocystis was significantly less prevalent in the antibiotic-treated group (16%) compared to non-antibiotic treated controls (55%); Fisher's Exact test, p < 0.0001). Given that antibiotics target structures and molecules of prokaryotic cells to kill or inhibit bacterial populations, the most likely explanation for differences in prevalence between both groups is due to secondary extinctions owing to the potential dependence of Blastocystis on bacteria present in the gut microbiome that were negatively affected by antibiotic treatment. Although further work is required to explore this hypothesis in greater detail, these data clearly show that Blastocystis prevalence in human populations is negatively associated with antibiotic treatment. This finding may be relevant to explaining patterns of variation for this microorganism in different human populations and cohorts of interest.

Intestinal protozoa and helminths in ulcerative colitis and the influence of anti-parasitic therapy on the course of the disease.

PURPOSE: The aim of this study is to determine the prevalence of intestinal helminths and protozoa in patients with ulcerative colitis (UC) and to estimate the influence of the anti-parasitic therapy on the course of the disease. METHODS: The study was conducted at the Research Institute of Epidemiology, Microbiology and Infectious Diseases and Coloproctology Department of the Republic Clinical Hospital №1 of the Ministry of Health of the Republic of Uzbekistan. One hundred UC patients and 200 healthy individuals were examined by triple coproscopy. Additionally, 20, 25 and 22 UC patients with Blastocystis infection were treated with nitazoxanide (1.0 g/day), mesalazine (1.5-2 g/day) or a combination of nitazoxanide (1.0 g/day) and mesalazine (≥1.5-2 g/day) for 14 consecutive days, respectively. Parasitological, clinical and endoscopic examinations were conducted before therapy, immediately after and 6 and 12 weeks after therapy completion. RESULTS: The overall prevalence of helminths in UC patients and control individuals was not significantly different: 14±3.4% and 8.5±1.9%, respectively (OR: 1.7524; 95% CI: 0.8258 to 3.7186; P=0.1). Giardia lamblia was the most prevalent parasite in both groups, but the difference compared to the control was insignificant (OR: 0.4565; 95% CI: 0.2020 to 1.0318; P=0.05). A significantly higher prevalence of Blastocystis sp., Chilomastix mesnili and Iodamoeba butschlii in UC patients compared to control individuals was found (P<0.0005): 65.0%, 14.0% and 22.0%, respectively. During all follow-up periods, the clinical response and clinical remission were not statistically different between the groups (P>0.05). Mucosal healing immediately and 6 weeks after therapy with a combination of nitazoxanide with mesalazine was significantly better than with a monotherapy of nitazoxanide, respectively (P<0.05). UC patients treated with a combination of nitazoxanide with mesalazine showed better mucosal healing than in patients treated with a monotherapy of mesalazine (P>0.05). CONCLUSIONS: Diagnosis of Blastocystis sp. should be introduced in the complex examination of UC patients. Further clinical studies are necessary for assessment of the efficiency of anti-Blastocystis therapy in UC patients.

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 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.

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.

Saccharomyces boulardii inhibits the expression of pro-inflammatory cytokines and inducible nitric oxide synthase genes in the colonic mucosa of rats experimentally-infected with Blastocystis subtype-3 cysts.

Blastocystis spp. is the most frequent infectious unicellular, luminal parasite in all species of animals and humans. It has been linked to diarrhoea and irritable bowel syndrome. Saccharomyces boulardii (Sb) is a widely used probiotic that previously showed efficacy against several intestinal pathogens. The aim of this study was to investigate the therapeutic role of Sb on Blastocystis spp. Methods: Five groups of Blastocystis subtype-3 infected rats were treated with either live Sb alone, metronidazole (MTZ) alone, Sb extract, both Sb and MTZ, or placebo-treated besides the noninfected control group. Assessment of treatment effectiveness was done by study of parasitological cure rate, histopathological effect and analysis of the colonic mucosal level of mRNAs expressions for the proinflammatory cytokines interleukin-6 (IL-6), IL-8, tumour necrosis factor alpha (TNF-α) and Inducible nitric oxide synthase (iNOS) by real-time reverse transcription-polymerase chain reaction (real-time RT-PCR). Results showed that live Sb significantly improved the histological characteristics and decreased the cytokines and iNOS in the colonic mucosa. Co-administration of live Sb together with MTZ gave a better effect than other treatments and had early efficacy and revealed a 100% reduction of the parasite stages from both the stool and intestinal wash fluid.

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.

Extra-enteric Blastocystis infection in a duck.

Cell structures morphologically consistent with Blastocystis were aspirated from a subcutaneous facial swelling in a 13-mo-old pet duck. On PCR analysis and sequencing, the organism was confirmed as Blastocystis sp. subtype 7. Blastocystis is a single-celled protist that is found in the intestinal tract of many species, including mammals, birds, reptiles, amphibians, and insects. A complete understanding of the lifecycle and pathogenesis of the parasite remains elusive. Blastocystis has been implicated in human and animal disease; however, its role is controversial given that it is commonly found among healthy gut microbiota. Infection with Blastocystis outside the intestinal tract has been reported only rarely in humans. Our case of subcutaneous Blastocystis infection in a duck is a novel presentation of a ubiquitous, generally asymptomatic, parasite or commensal of the intestinal tract.

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.

Atorvastatin: In-Vivo Synergy with Metronidazole as Anti-Blastocystis Therapy.

Blastocystis is an enteric Straminopile in tropical, subtropical and developing countries. Metronidazole has been a chemotheraputic for blastocystosis. Failures in its regimens were reported and necessitate new studies searching for alternative therapeutic agents. Aim of current study is to investigate potential effects of Atorvastatin (AVA) compared to the conventional chemotherapeutic MTZ in experimentally Blastocystis-infected mice. Anti-Blastocystis efficacy of AVA was evaluated parasitologically, histopathologically and by transmission electron microscopy using MTZ (10 mg/kg) as a control. Therapeutic efficacy of AVA was apparently dose-dependent. Regimens of AVA (20 and 40 mg/kg) proved effective against Blastocystis infections with high reduction in Blastocystis shedding (93.4-97.9%) compared to MTZ (79.3%). The highest reductions (98.1% and 99.4%) were recorded in groups of combination treatments AVA 20-40 mg/kg and MTZ 10 mg/kg. Blastocystis was nearly eradicated by the 20th day post infection. Genotype analysis revealed that genotype I was most susceptible, genotype III was less. Histopathologic and ultrastructural studies revealed apoptotic changes in Blastocystis and significant improvement of intestinal histopathological changes more remarkable in combinational therapy groups. Thus, the present study offers AVA as a potential candidate for Blastocystis therapy combined with MTZ.

Un parásito emergente de patogenicidad controvertida, Blastocystis sp.: ¿Hay que tratar a todos los pacientes? / Blastocystis sp., an emerging parasite with controversial pathogenicity. Should all human cases be treated?

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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.

Estudio epidemiológico de parásitos en niños de Sevilla / Epidemiological study of parasites in children in Seville

Introducción. Las parasitosis intestinales son infestaciones de microorganismos, cuyo hábitat habitual es el tracto digestivo del hospedador. La distribución es mundial, con mayor prevalencia en zonas insalubres. En España, constituyen un 10% del total de las causas de. diarreas, con tendencia al aumento. Aunque no representan un problema tan importante como en los países en desarrollo, algunas parasitosis previamente infrecuentes están empezando a aparecer en nuestro medio y es importante conocerlas, sospecharlas y mejorar la terapéutica. Por ello, realizamos este trabajo con el fin de analizar la frecuencia de distintos parásitos intestinales en nuestro entorno, revisar las indicaciones de solicitud de estudio de parásitos en heces y aumentar su rentabilidad. Materiales y métodos. Análisis descriptivo, transversal y retrospectivo de los datos registrados en la base de datos informatizada de estudios de parásitos fecales realizados durante el período 2010—2014. Todos los estudios han sido solicitados en Centros de Atención Primaria y realizados en el Servicio de Microbiología del Hospital Universitario Virgen del Rocío, de Sevilla. Resultados. Encontramos un resultado patológico en un 9,3 % de las muestras. El parásito más frecuente fue Giardia lamblia seguido de Blastocystis spp. En menores de un año fueron patológicas el 3,7% de las muestras y solo se visualizaron dos tipos de parásitos (Cryptosporidinm spp. y Giardia lamblia). En el grupo de edad de 1 4 años fueron positivas un 9,9% del total de muestras remitida si bien se hallaron hasta 12 tipos de parásitos, el más frecuéntemente encontrado ha sido Blastocystis spp. seguido de Giardia lamblia. Conclusiones. El parásito intestinal más frecuente en nuestro entorno es Giardia lamblia, aunque se obsservan variaciones según el grupo de edad estudiado. La recogida de muestras según los protocolos establecidos y la sospecha clinica fundada son imprescindibles para optimizar el diagnóstico de las parasitosis intestinales (AU)

Introduction. intestinal parasitosis are infestations of microorganisms, whose habitat is usually the digestive tract of the host. They have a worldwide distribution, with higher prevalence in unhealthy areas. In Spain, they constitute 10% of the total causes of diarrhea, with a tendency to increase. Although they do not represent a problem as important as in the developing countries, some previously frequent parasitosis are beginning to appear in our environment and it is important to know them, to suspect them and to improve the therapeutics. Therefore, we performed this work in order to analyze the frequency of different intestinal parasites in our environment, to review the indications for the study of feces parasites and to increase their profitability. Materials and methods. Descriptive, crosss-sectional and retrospective analysis of the data recorded in the computerized database for fecal parasite studies conducted during the period 2010-2014. All the studies have been requested in Primary Health Centers and performed at the Microbiology Service of the University Hospital Virgen del Rocío, Sevilla. Results. We found a pathological result in 9.3% of the samples. The most frequent parasite was Giardia lamblia followed by Blastocystis spp. In patients less than one year old, 3.7% of the samples were pathological and only two types of parasites (Cryptosporidium spp. and Giardia lamblia) were visualized. In patients between 10-14 years old, 9.9% of the total samples were pathological and, although up to 12 types of parasites were found, the most frequently found was Blastocystis spp. followed by Giardia lamblia. Conclusions. The most frequent intestinal parasite in our environment is Giardia iamblia, although variations are observed according to the studied age group. The collection of samples according to the established protocols and the established clinical suspicion are essential to optimize the diagnosis of intestinal parasitosis (AU)

Escasa eficacia de metronidazol en la erradicación de Blastocystis hominis en pacientes sintomáticos: serie de casos y revisión sistemática de la literatura / Low efficacy of metronidazole in the eradication of Blastocystis hominis in symptomatic patients: Case series and systematic literature review

Introducción: El Blastocystis hominis (B. hominis) es un protozoo comúnmente encontrado en el tracto gastrointestinal. Existen dudas sobre su significado clínico. El metronidazol (MTZ) es el tratamiento aconsejado de primera línea. Material y métodos: Se realizó una revisión retrospectiva entre 2011 y 2012. Se seleccionaron de forma aleatoria 151 de 383 muestras positivas para B. hominis. Los criterios de inclusión fueron: clínica sugestiva, indicación de tratamiento y realización de control microbiológico. Se realizó una revisión sistemática de los estudios que evalúan el efecto de MTZ sobre la infestación por B. hominis. Resultados: Cuarenta y seis pacientes cumplían criterios de inclusión (el 64% eran mujeres; edad, 44,2±2 años). Se utilizó MTZ en 39 pacientes, de los cuales 31 obtuvieron respuesta clínica (79,5%) pero solo 15 respuesta microbiológica (48,4%). No se apreció una relación dosisefecto. Veinte pacientes sin respuesta microbiológica inicial recibieron una segunda tanda de tratamiento (MTZ, cotrimoxazol, paramomicina, otros), con una respuesta microbiológica del 70%. De forma global, se consiguió la curación de B. hominis en un 72% (IC95%: 57-83%). De 54 tratamientos asociados a respuesta clínica, se produjo respuesta microbiológica en 31 (57%); mientras que de los 12 que se siguieron de ausencia de respuesta clínica solo se observó la curación microbiológica en 2 (17%) (p = 0,022). La tasa de erradicación en la revisión sistemática osciló entre 0 y 100%. Conclusiones: Parece existir relación entre la respuesta clínica y microbiológica al tratamiento de B. hominis. En nuestro entorno geográfico la respuesta microbiológica al tratamiento con MTZ es insuficiente. La revisión sistemática muestra que la respuesta a MTZ es muy variable (AU)

Introduction: Blastocystis hominis (B. hominis) is a protozoan commonly found in the gastrointestinal tract. There are doubts about its clinical significance. Metronidazole (MTZ) is the recommended first-line treatment. Materials and methods: A retrospective review was carried out between 2011 and 2012. A total of 151 samples were randomly selected from 383 samples positive for B. hominis. Inclusion criteria were: suggestive symptoms, treatment indication and microbiological follow-up. A systematic review was performed of all studies that evaluated the effect of MTZ on B. hominis infection. Results: Forty-six patients met the inclusion criteria (64% women; age, 44.2±2 years). MTZ was used in 39 patients, 31 of whom obtained a clinical response (79.5%) but only 15 a microbiological response (48.4%). No dose-effect relationship was observed. Twenty patients with no initial microbiological response received a second round of treatment (MTZ, cotrimoxazole, paramomycin, others), with a microbiological response in 70%. Overall, B. hominis was cured in 72% (95% CI: 57%-83%). Of 54 treatments associated with a clinical response, a microbiological response occurred in 31 (57%), while in the remaining 12 with no clinical response, microbiological cure was observed in only 2 (17%) (P = .022). The eradication rate in the systematic review varied between 0% and 100%. Conclusions: There seems to be a relationship between the clinical and microbiological response to B. hominis treatment. The microbiological response to MTZ treatment is insufficient in our geographical setting. The systematic review shows that the response to MTZ is very variable (AU)

Low efficacy of metronidazole in the eradication of Blastocystis hominis in symptomatic patients: Case series and systematic literature review. / Escasa eficacia de metronidazol en la erradicación de Blastocystis hominis en pacientes sintomáticos: serie de casos y revisión sistemática de la literatura.

INTRODUCTION: Blastocystis hominis (B. hominis) is a protozoan commonly found in the gastrointestinal tract. There are doubts about its clinical significance. Metronidazole (MTZ) is the recommended first-line treatment. MATERIALS AND METHODS: A retrospective review was carried out between 2011 and 2012. A total of 151 samples were randomly selected from 383 samples positive for B. hominis. Inclusion criteria were: suggestive symptoms, treatment indication and microbiological follow-up. A systematic review was performed of all studies that evaluated the effect of MTZ on B. hominis infection. RESULTS: Forty-six patients met the inclusion criteria (64% women; age, 44.2±2 years). MTZ was used in 39 patients, 31 of whom obtained a clinical response (79.5%) but only 15 a microbiological response (48.4%). No dose-effect relationship was observed. Twenty patients with no initial microbiological response received a second round of treatment (MTZ, cotrimoxazole, paramomycin, others), with a microbiological response in 70%. Overall, B. hominis was cured in 72% (95% CI: 57%-83%). Of 54 treatments associated with a clinical response, a microbiological response occurred in 31 (57%), while in the remaining 12 with no clinical response, microbiological cure was observed in only 2 (17%) (P=.022). The eradication rate in the systematic review varied between 0% and 100%. CONCLUSIONS: There seems to be a relationship between the clinical and microbiological response to B. hominis treatment. The microbiological response to MTZ treatment is insufficient in our geographical setting. The systematic review shows that the response to MTZ is very variable.

Blastocystis: how do specific diets and human gut microbiota affect its development and pathogenicity?

Blastocystis is an enteric parasite that inhabits the gastrointestinal tract of humans and many animals. This emerging parasite has a worldwide distribution. It is often identified as the most common eukaryotic organism reported in human fecal samples. This parasite is recognized and diagnosed more often than ever before. Furthermore, some strains develop resistance against currently recommended drugs, such as metronidazole; therefore, the use of natural remedies or special diets has many positive aspects that may address this problem. The goal of this review is to compare natural treatments and various diets against the efficacy of drugs, and describe their influence on the composition of the gut microbiota, which affects Blastocystis growth and the occurrence of symptoms. This article reviews important work in the literature, including the classification, life cycle, epidemiology, pathogenesis, pathogenicity, genetics, biology, and treatment of Blastocystis. It also includes a review of the current knowledge about human gut microbiota and various diets proposed for Blastocystis eradication. The literature has revealed that garlic, ginger, some medical plants, and many spices contain the most effective organic compounds for parasite eradication. They work by inhibiting parasitic enzymes and nucleic acids, as well as by inhibiting protein synthesis. The efficacy of any specific organic compound depends on the Blastocystis subtype, and, consequently, on its immunity to treatment. In conclusion, the article discusses the findings that human gut microbiota composition triggers important mechanisms at the molecular level, and, thus, has a crucial influence on the parasitic pathogenicity.