Diagnostic and Therapeutic Considerations Towards Dientamoeba fragilis in Children: A Survey Amongst General Practitioners and Pediatricians in the Netherlands.

ABSTRACT: This survey was undertaken to obtain insight in the attitude of Dutch physicians towards pathogenicity, diagnostic- and therapeutic approach towards Dientamoeba fragilis in children. Physicians were invited by e-mail for a questionnaire. A total of 211 of 450 physicians (46.9%) completed the questionnaire, including 67 general practitioners (GPs) and 144 pediatricians. Of all respondents, 175 of 211 (82.9%) considered D fragilis a "potential pathogen", when other causes of gastro-intestinal complaints are ruled out. Only 16 of 211 (7.6%) performed diagnostic tests regularly. Diagnostic tests were performed by 162 of 211 (77%) of respondents in children with diarrhea and abdominal pain in consideration of duration of symptoms. Fecal polymerase chain reaction (PCR) was diagnostic modality of preference. Eighty-nine of 142 (62.7%) prescribed metronidazole as antibiotic of first choice. This study shows heterogeneity in clinical practice amongst Dutch physicians regarding diagnostic- and therapeutic approach of D fragilis in children. Different attitude towards pathogenicity and inconsistent guidelines could be causative factors.

Impact of Metronidazole Treatment and Dientamoeba Fragilis Colonization on Gut Microbiota Diversity.

OBJECTIVES: The intestinal parasite Dientamoeba fragilis is a common colonizer of children in Denmark. Metronidazole has been used to reduce gastrointestinal symptoms in children colonized with D fragilis. We aimed to identify gut microbiota changes associated with D fragilis carrier status and metronidazole treatment of D fragilis-positive children. METHODS: The fecal microbiota of 275 fecal samples from children treated with metronidazole (n = 48) or placebo (n = 48) were characterized by ribosomal DNA sequencing. Samples collected before (T1), 2 weeks after (T2), and 8 weeks (T5) after treatment were included. Seventy fecal samples from 70 age-matched parasite-negative children served as controls. RESULTS: The abundance of 24 bacterial genera differed significantly according to D fragilis carrier status, with Flavonifractor being remarkably more abundant in children testing negative for D fragilis. Eight bacterial genera changed significantly in abundance in children losing versus keeping D fragilis after metronidazole treatment. Of these, 7 returned to pretreatment (T1) levels at T5. Meanwhile, the abundance of Flavonifractor continued to differ at T5, whereas for Ruminococcus the abundance only remained high in children who were D fragilis-negative at T2 and T5. Increases in Hungatella, Sutterella, and Streptococcus abundances observed at T2 were specific to metronidazole exposure and hence independent of D fragilis colonization. CONCLUSIONS: This study revealed that specific bacterial genera were associated with D fragilis colonization. Metronidazole treatment had a short-term impact on the abundance of some bacterial genera, with most of these reverting to pretreatment levels 8 weeks after completed treatment.

Dientamoeba fragilis in children: a systematic review on diagnostic considerations and efficacy of treatment.

Introduction: The presence of D. fragilis in feces is characterized by an asymptomatic carrier ship to a spectrum of gastrointestinal symptoms. However, a causal relationship remains to be elucidated. In this systematic review, we aimed to evaluate the relationship between the eradication of D. fragilis and symptoms to establish the strength of evidence that D. fragilis in symptomatic children warrants antibiotic treatment.Areas covered: This systematic review covers a challenge in daily clinical practice. Is it necessary to test for D. fragilis in children with gastrointestinal symptoms and does a positive fecal PCR test warrant treatment?Expert opinion: Testing for D. fragilis seems justified in a selection of children with persistent unexplained chronic abdominal pain and diarrhea. Treatment of D. fragilis should be withhold until other causes like celiac disease have been excluded. Both microscopic and Real Time-PCR methods (or a combination of the two) can be used for diagnosis. Paromomycin or clioquinol are antibiotics of choice based on their small spectrum of activity, fewer side effects, and better eradication rates than metronidazole. Future randomized studies, with strict inclusion criteria, appropriate diagnostic testing, and doses of antibiotics based on bodyweight are warranted.

Paromomycin is superior to metronidazole in Dientamoeba fragilis treatment.

Dientamoeba fragilis is a trichomonad parasite of the human intestine that is found worldwide. However, the biological cycle and transmission of this parasite have yet to be elucidated. Although its pathogenic capacity has been questioned, there is increasing evidence that clinical manifestations vary greatly. Different therapeutic options with antiparasitic drugs are currently available; however, very few studies have compared the effectiveness of these drugs. In the present longitudinal study, we evaluate 13,983 copro-parasitological studies using light microscopy of stools, during 2013-2015, in Terrassa, Barcelona (Spain). A total of 1150 (8.2%) presented D. fragilis. Of these, 739 episodes were finally analyzed: those that involved a follow-up parasitology test up to 3 months later, corresponding to 586 patients with gastrointestinal symptoms (53% under 15 years of age). Coinfection by Blastocystis hominis was present in 33.6% of the subjects. Our aim was to compare therapeutic responses to different antiparasitic drugs and the factors associated with the persistence of D. fragilis post-treatment. Gender, age, and other intestinal parasitic coinfections were not associated with parasite persistence following treatment. Metronidazole was the therapeutic option in most cases, followed by paromomycin: 65.4% and 17.5% respectively. Paromomycin was found to be more effective at eradicating parasitic infection than metronidazole (81.8% vs. 65.4%; p = 0.007), except in children under six years of age (p = 0.538). Although Dientamoeba fragilis mainly produces mild clinical manifestations, the high burden of infection means we require better understanding of its epidemiological cycle and pathogenicity, as well as adequate therapeutic guidelines in order to adapt medical care and policies to respond to this health problem.

Epidemiological and clinical characteristics of Dientamoeba fragilis infection / Características clínicoepidemiológicas de las infecciones por Dientamoeba fragilis

INTRODUCTION: The characteristics of D. fragilis infection are described, with special focus on the clinical and epidemiological aspects. MATERIALS AND METHODS: A retrospective and descriptive study was performed, including all the patients with Dientamoeba fragilis infection who attended a specialized unit between January 2012 and December 2017. PCR was used to diagnose D. fragilis. Patients were treated with metronidazole or paromomycin and reviewed at four and eight weeks post-treatment. Cure was defined as the negativization of all parasitological tests, in absence of symptoms. RESULTS: 163 patients were diagnosed. The most frequent symptoms were abdominal pain (36.2%), chronic diarrhoea (12.3%), anal itching (10.4%), abdominal discomfort (9.2%), skin disease (8%), acute diarrhoea (4.3%) and vomiting (4.3%). Fifty patients were asymptomatic. Forty-two patients had eosinophilia in blood. Thirty-eight cases (23.3%) had a coinfection by Enterobius vermicularis. One hundred and seven patients received treatment, sixty-one of them with metronidazole and the rest with paromomycin. Ninety-nine patients (91%) were cured. The rate of cure was 100% in the paromomycin group versus 86.8% in the metronidazole group (p = 0.005; OR: 1.173 [1.057-1.302]). The absence of cure was associated with E. vermicularis coinfection (p = 0.014; OR: 6.167 [1.432-26.563] and with longer duration of the symptoms (175 [± 159SD]) versus 84 [± 88SD] days, p = 0.014) but multivariable analysis did not confirm these associations. CONCLUSION: Dientamoeba fragilis is an important and underestimated cause of gastrointestinal disease in both the autochthonous and immigrant or traveller population. More studies are needed to clarify its optimal treatment and the role played by E. vermicularis in its transmission and maintenance

INTRODUCCIÓN: Se describen las características clínicas y epidemiológicas de la infección por Dientamoeba fragilis. MATERIAL Y MÉTODOS: Se realizó un estudio retrospectivo y descriptivo de los pacientes diagnosticados de infección por D. fragilis en una unidad especializada entre 2012-2017. El diagnóstico de D. fragilis se realizó mediante PCR. Los pacientes fueron tratados con metronidazol o paromomicina y revisados a las 4 y 8 semanas tras tratamiento. Se consideró a los pacientes curados tras negativización microbiológica en ausencia de síntomas. RESULTADOS: Se analizaron 163 pacientes. Los síntomas más frecuentes fueron: dolor abdominal (36,2%), diarrea crónica (12,3%), prurito anal (10,4%), malestar abdominal (9,2%), síntomas cutáneos (8%), diarrea aguda y vómitos (4,3%, respectivamente). Cincuenta pacientes estaban asintomáticos. Cuarenta y dos pacientes presentaron eosinofilia. En 38 pacientes se observó coinfección por Enterobius vermicularis. Ciento siete pacientes recibieron tratamiento, 61 con metronidazol y el resto con paromomicina, con una curación del 91%. La tasa de curación fue del 100% en los pacientes tratados con paromomicina y del 86,8% en el grupo del metronidazol (p = 0,005; OR: 1,173 [1,057-1,302]). La no curación se asoció a la coinfección por E. vermicularis (p = 0,014; OR: 6,167 [1,432-26,563]) y con la mayor duración de los síntomas (175 [± 159 DE] versus 84 [± 88 DE] días; p = 0,014), pero el análisis multivariable no confirmó dichas asociaciones. CONCLUSIÓN: D. fragilis es causa importante y subestimada de enfermedad gastrointestinal tanto en poblaciones autóctonas como inmigrantes o viajeros. Se necesitan más estudios para aclarar su tratamiento óptimo y el papel desempeñado por E. vermicularis en su tratamiento

Epidemiological and clinical characteristics of Dientamoeba fragilis infection.

INTRODUCTION: The characteristics of D. fragilis infection are described, with special focus on the clinical and epidemiological aspects. MATERIALS AND METHODS: A retrospective and descriptive study was performed, including all the patients with Dientamoeba fragilis infection who attended a specialized unit between January 2012 and December 2017. PCR was used to diagnose D. fragilis. Patients were treated with metronidazole or paromomycin and reviewed at four and eight weeks post-treatment. Cure was defined as the negativization of all parasitological tests, in absence of symptoms. RESULTS: 163 patients were diagnosed. The most frequent symptoms were abdominal pain (36.2%), chronic diarrhoea (12.3%), anal itching (10.4%), abdominal discomfort (9.2%), skin disease (8%), acute diarrhoea (4.3%) and vomiting (4.3%). Fifty patients were asymptomatic. Forty-two patients had eosinophilia in blood. Thirty-eight cases (23.3%) had a coinfection by Enterobius vermicularis. One hundred and seven patients received treatment, sixty-one of them with metronidazole and the rest with paromomycin. Ninety-nine patients (91%) were cured. The rate of cure was 100% in the paromomycin group versus 86.8% in the metronidazole group (p=0.005; OR: 1.173 [1.057-1.302]). The absence of cure was associated with E. vermicularis coinfection (p=0.014; OR: 6.167 [1.432-26.563] and with longer duration of the symptoms (175 [±159SD]) versus 84 [±88SD] days, p=0.014) but multivariable analysis did not confirm these associations. CONCLUSION: Dientamoeba fragilis is an important and underestimated cause of gastrointestinal disease in both the autochthonous and immigrant or traveller population. More studies are needed to clarify its optimal treatment and the role played by E. vermicularis in its transmission and maintenance.

A clinical guideline on Dientamoeba fragilis infections.

Dientamoeba fragilis (D. fragilis) is an intestinal parasite frequently detected in humans with abdominal pain and diarrhoea, but it is also commonly found in asymptomatic subjects. Hence its clinical relevance is often disputed. The introduction of polymerase chain reaction (PCR) is a versatile and sensitive diagnostic technique for the detection of intestinal parasites, and in some Western world countries PCR has almost completely replaced microscopic diagnostics. PCR has however resulted in an increase in the number of D. fragilis-positive patients. The disputed pathogenic nature of this intestinal parasite and an apparent increase in the incidence of patients with positive PCR results have renewed the discussions between clinicians and microbiologists on how to deal with an infected patient. Moreover, treatment guidelines differ throughout the world which makes it difficult for clinicians to choose an optimal therapeutic regimen.AimTo summarize and discuss the current knowledge on the pathogenicity, best diagnostic approach, treatment and follow-up of children and adults infected with D. fragilis.

Clinical and Epidemiological Characteristics of Patients with Dientamoeba fragilis Infection.

Dientamoeba fragilis is an intestinal protozoan, usually considered nonpathogenic. However, in the last years, there has been an attempt to clarify its possible pathogenic role. We aim to evaluate the clinical and epidemiological characteristics of D. fragilis-infected patients. Adults with D. fragilis detection in feces who attended the Vall d'Hebron University Hospital (Barcelona, Spain) were evaluated retrospectively from April 2009 to March 2014. We classified the patients in asymptomatic, symptomatic without other causes except infection of D. fragilis, and symptomatic with another cause. Among symptomatic patients, treatment response was evaluated. One hundred eight patients were included. Sixty-three percent of the patients were immigrants, 29.6% were autochthonous, and 7.4% were travelers. Forty-nine (45.3%) patients presented symptoms, and eosinophilia was observed in 26 (24.1%) patients. Overall, 59 (54.7%) patients were asymptomatic, 15 (13.8%) presented symptoms which were attributable to other causes, and 34 (31.5%) patients presented symptoms with no other causes. In this last group, 29 patients received specific treatment and 65.5% of them presented a complete resolution of the symptoms. The group of symptomatic patients with no other cause had more proportion of women, more proportion of autochthonous people, and were older compared with the group of asymptomatic patients. Dientamoeba fragilis infection should be considered as pathogenic when other causes are ruled out.

[Clioquinol use for Dientamoeba fragilis infections is questionable]. / Clioquinol voor Dientamoeba fragilis-infectie discutabel.

Clioquinol is used for treatment of amoebiasis and infection with Dientamoeba fragilis. In a guideline of the Dutch Working Party on Antibiotic Policy, clioquinol is recommended as a first-choice treatment for Dientamoeba fragilis. This drug, however, is associated with subacute myelo-optico-neuropathy (SMON). It was withdrawn from the market worldwide in 1985 by manufacturer Ciba-Geigy. Although the Dutch Medicines Evaluation Board has registered no products for systemic use of clioquinol since then, the drug is available as a pharmacy-compounded drug and the last few years the use of clioquinol in the Netherlands has risen again. The Netherlands Pharmacovigilance Centre Lareb has received a growing number of reports of adverse drug reactions (ADRs) associated with the use of clioquinol, including nervous system disorder ADRs occurring at recommended dosages. Therefore, we debate the use of clioquinol as a first-choice treatment option for Dientamoeba fragilis.

Is the treatment of Enterobius vermicularis co-infection necessary to eradicate Dientamoeba fragilis infection?

OBJECTIVES: Dientamoeba fragilis is a pathogenic protozoan of the human gastrointestinal tract with a worldwide distribution, which has emerged as an important and misdiagnosed cause of chronic gastrointestinal illnesses such as diarrhea and 'irritable-bowel-like' gastrointestinal disease. Very little research has been conducted on the use of suitable antimicrobial compounds. Furthermore, higher rates of co-infection with Enterobius vermicularis have been described, suggesting that E. vermicularis could influence the treatment of D. fragilis-infected patients. To study this, the treatment of E. vermicularis and D. fragilis co-infected patients was evaluated. METHODS: Forty-nine patients with a D. fragilis infection, including 25 (51.0%) patients co-infected with E. vermicularis, were studied. All of them were treated with metronidazole. Patients with E. vermicularis co-infection and/or an E. vermicularis-positive case in the family were treated with mebendazole. RESULTS: Metronidazole treatment failure was significantly more frequent in patients with E. vermicularis co-infection and in patients with children in the family. CONCLUSIONS: Co-infection with E. vermicularis may act as a factor favoring D. fragilis infection by preventing eradication measures. This suggests that both parasites should be treated simultaneously.

Dientamoeba fragilis, One of the Neglected Intestinal Protozoa.

Dientamoeba fragilis is a single-celled protozoan, closely related to the trichomonads. Reported worldwide as causing human gastrointestinal symptoms, D. fragilis is very common and is second only to Blastocystis spp. Dientamoebiasis equals or exceeds the incidence of giardiasis. This minireview includes diagnostic options, clinical relevance, therapy, an animal model, the confirmed cyst stage, and sequencing data. The development of a rodent model, fulfilling Koch's postulates, and the confirmation of a cyst stage have clarified transmission routes, including fecal-oral transmission. The prevalence of D. fragilis varies between 0% to over 82%; results depend on the geographic location, group studied, and diagnostic methods used.

The Transcriptome Sequence of Dientamoeba fragilis Offers New Biological Insights on its Metabolism, Kinome, Degradome and Potential Mechanisms of Pathogenicity.

Dientamoeba fragilis is a human bowel parasite with a worldwide distribution. Dientamoeba was once described as a rare and harmless commensal though recent reports suggest it is common and potentially pathogenic. Molecular data on Dientamoeba is scarce which limits our understanding of this parasite. To address this, sequencing of the Dientamoeba transcriptome was performed. Messenger RNA was extracted from cultured Dientamoeba trophozoites originating from clinical stool specimens, and sequenced using Roche GS FLX and Illumina HiSeq technologies. In total 6,595 Dientamoeba transcripts were identified. These sequences were analysed using the BLAST2GO software suite and via BLAST comparisons to sequences available from TrichDB, GenBank, MEROPS and kinase.com. Several novel KEGG pathway maps were generated and gene ontology analysis was also performed. These results are thoroughly discussed guided by knowledge available for other related protozoa. Attention is paid to the novel biological insights afforded by this data including peptidases and kinases of Dientamoeba, as well as its metabolism, novel chemotherapeutics and possible mechanisms of pathogenicity. Currently, this work represents the largest contribution to our understanding of Dientamoeba molecular biology and also represents a major contribution to our understanding of the trichomonads generally, many of which are important pathogens of humans and animals.

[Dientamoeba fragilis infection as cause of severe abdominal discomfort and flatulence]. / Dientamoeba fragilis-infektion som årsag til meteorisme og flatulens.

The clinical significance of Dientamoeba fragilis infection is controversial. We describe a case-history of a 16-year-old patient, who had suffered severe abdominal discomfort and flatulence through his lifetime. He was eventually diagnosed with D. fragilis infection, and eradication of D. fragilis with high-dose metronidazole kept him without symptoms for one year. Recurrence of the symptoms and recurrence of the D. fragilis infection was thereafter treated successfully with paromomycin.

Dientamoeba fragilis and chronic abdominal pain in children: a case-control study.

BACKGROUND: The association between Dientamoeba (D.) fragilis and the aetiology of functional gastrointestinal disorders (FGID) in children is unclear. AIM: The aim of this retrospective case-control study is to clarify the clinical relevance of D. fragilis in children with chronic abdominal pain. METHODS: From April 2011 until April 2013, a total of 132 patients with chronic abdominal pain (AP), aged 8-18 years, referred to a non-academic hospital, and 77 control patients, aged 8-18 years without gastrointestinal symptoms referred to a psychiatric hospital, were included in the study. D. fragilis was diagnosed by real-time PCR in faecal samples. Symptomatic children without a D. fragilis infection fulfilled the ROME III criteria for AP-related FGID (AP-FGID). Clinical data were retrospectively analysed by examining patients' hospital records from the Jeroen Bosch Hospital and Herlaarhof in The Netherlands. RESULTS: D. fragilis was detected in 57 patients with chronic AP (43.2%) and in 39 controls (50.6%) (p=0.255). No significant differences in symptomatology were found between D. fragilis-infected children and children fulfilling the criteria for AP-FGID. Parasitological eradication was achieved in 61.7% of patients after treatment with metronidazole or clioquinol, while clinical improvement occurred in only 40.4% of patients (p=0.435). CONCLUSIONS: There were no differences in symptoms comparing children with and without D fragilis infection. Furthermore, no relation was found between clinical and microbiological response after treatment for D. fragilis. This retrospective study suggests that there is no association between chronic AP and D. fragilis infection.

Metronidazole therapy for treating dientamoebiasis in children is not associated with better clinical outcomes: a randomized, double-blinded and placebo-controlled clinical trial.

BACKGROUND: There is a paucity of evidence documenting the pathogenicity of Dientamoeba fragilis, an intestinal protozoan common in children. As case reports on successful treatment are numerous, many authors advocate treatment, despite no placebo-controlled trials being available. Metronidazole is often used for treatment, though eradication rates are relatively low (60%-80%). In the present study we determined the clinical and microbiological efficacy of metronidazole in Danish children. METHODS: In this parallel placebo-controlled double-blinded trial, children aged 3-12 years with >4 weeks of gastrointestinal symptoms were allocated using block randomization in a 1:1 ratio to a 10-day course of oral metronidazole or placebo. Primary outcome was change in level of gastrointestinal symptoms, measured on a visual-analog-scale (VAS), and secondary outcome was eradication of D. fragilis infection. Participants, caregivers, investigators, and sponsor were all blinded to group assignment. The trial was registered with clinicaltrials.gov (NCT01314976) prior to start. RESULTS: Of 96 participants, 48 were allocated to the metronidazole and placebo group each. Mean VAS change from pre- to post-treatment did not differ significantly (P = .8) between the metronidazole (-1.8 CI, [-2.5, -1.1]) and the placebo group (-1.6 CI, [-2.3, -.9]). Eradication of D. fragilis was significantly greater in the metronidazole group, although it declined rapidly from 62.5% 2 weeks after end of treatment to 24.9% 8 weeks after end of treatment. CONCLUSIONS: These findings do not provide evidence to support routine metronidazole treatment of D. fragilis positive children with chronic gastrointestinal symptoms. Study funded by Statens Serum Institut. CLINICAL TRIALS REGISTRATION: Trial was registered with clinicaltrials.gov (NCT01314976).

[Role of Dientamoeba fragilis and Blastocystis spp. in Irritable Bowel Syndrome]. / Irrite Bagirsak Sendromunda Dientamoeba fragilis ve Blastocystis spp.'nin Rolü

OBJECTIVE: We investigated the prevalence of Dientamoeba fragilis and Blastocystis spp. in IBS patients and evaluated whether there was a possible link between IBS and these parasitic infections. METHODS: Stool specimens collected from 55 IBS patients, 80 patients with gastroenteritis as control group 1 (CG-1) and 50 healthy volunteers as control group 2 (CG-2) were included the study. Samples were examined by direct microscopy, trichrome staining and culture methods. RESULTS: While there was no significant difference in the prevalence of Blastocystis spp. between IBS patients and CG-1 (p > 0.05), a significant difference was found between IBS and CG-2 (p < 0.05). Patients with IBS were found to have five or more Blastocystis spp. per field than control groups. After eradication, all symptoms were cured in four patients, there were only constipation problems left in eleven patients and there were no changes in clinical findings in three patients. D. fragilis was not found in any of the samples. CONCLUSION: The reason we did not find any D. fragilis may be due to the low infection rate in the region. However, significantly having five or more Blastocystis spp. per field (X40) in IBS patients and regression of IBS symptoms after treatment in most of the patients suggested a possible link between IBS and Blastocystis spp.

Symptoms and treatment of Dientamoeba fragilis infection in children, a retrospective study.

INTRODUCTION: Dientamoeba fragilis infection in children is common, and its incidence has increased since the introduction of more sensitive molecular techniques. There is no consensus on the optimal treatment. Current medical practice in the Netherlands is to treat symptomatic children with clioquinol or metronidazole. This study attempts to obtain more information about the clinical picture of D. fragilis infection in children and to evaluate responses to both antiparasitic drugs. METHODS: Children <18 years of age with a positive stool polymerase chain reaction test for D. fragilis infection were retrospectively evaluated. Clinical data and effectiveness of treatment were analyzed by examining patient's hospital records from the Medical Centre Leeuwarden by repeated analysis of stool samples by the Centre for Infectious Diseases in Friesland. RESULTS: We analyzed 238 patients with an average age of 8.5 years (±4.2 years). Most patients were symptomatic (95.8%) and presented with abdominal pain (72.7%), loose stools (32.8%) and hard stools (24.8%). Coinfection with other gastrointestinal pathogens was present in 29 patients (12.2%). A higher incidence of infection was found in the winter. Clioquinol had a higher clinical success rate than metronidazole (74.7% versus 55.2%, P = 0.047). CONCLUSION: These results suggest that clioquinol could be more effective than metronidazole in alleviating symptoms of D. fragilis infection in children, but double-blind prospective placebo-controlled studies should be performed before final conclusions can be made.

Treatment of Dientamoeba fragilis in patients with irritable bowel syndrome.

The role of Dientamoeba fragilis in irritable bowel syndrome (IBS) is incompletely known. We aimed to investigate whether eradication of D. fragilis alleviates symptoms in IBS. Twenty-five D. fragilis-positive IBS patients were treated with Metronidazole (MZ) or Tetracycline. The patients were mostly female (89%), and mean age (SD) was 35.1 (8.2) years. Microbiological response, evaluated 2 weeks post-treatment, was observed in 15 of 25 patients (60%), all by MZ. Clinical response, defined as adequate relief of symptoms, was observed in 7 of 22 patients (32%), all by MZ. In a logistic regression analysis, we found no significant association between clinical and microbiological response. This case study did not support our hypothesis of a simple association between D. fragilis and IBS. Some D. fragilis-infections were insufficiently treated by MZ. Further studies into the prevalence and effect of eradication of D. fragilis in IBS and into efficient treatments of D. fragilis are warranted.

In vitro susceptibility testing of Dientamoeba fragilis.

Dientamoeba fragilis is a commonly encountered trichomonad which has been implicated as a cause of gastrointestinal disease in humans. Despite the frequency of reports recording infections with this parasite, little research has been undertaken in terms of antimicrobial susceptibility. The aim of this study was to evaluate the susceptibility of D. fragilis to several commonly used antiparasitic agents: diloxanide furoate, furazolidone, iodoquinol, metronidazole, nitazoxanide, ornidazole, paromomycin, secnidazole, ronidazole, tetracycline, and tinidazole. Antibiotic susceptibility testing was performed on four clinical strains of D. fragilis, designated A, E, M, and V, respectively. Molecular testing followed, and all strains were determined to be genotype 1. The activities of antiprotozoal compounds at concentrations ranging from 2 µg/ml to 500 µg/ml were determined via cell counts of D. fragilis trophozoites grown in dixenic culture. Minimum lethal concentrations (MLCs) were as follows: ornidazole, 8 to 16 µg/ml; ronidazole, 8 to 16 µg/ml; tinidazole, 31 µg/ml; metronidazole, 31 µg/ml; secnidazole, 31 to 63 µg/ml; nitazoxanide, 63 µg/ml; tetracycline, 250 µg/ml; furazolidone, 250 to 500 µg/ml; iodoquinol, 500 µg/ml; paromomycin, 500 µg/ml; and diloxanide furoate, >500 µg/ml. This is the first study to report the profiles of susceptibility to a wide range of commonly used treatments for clinical isolates of D. fragilis. Our study indicated 5-nitroimidazole derivatives to be the most active compounds in vitro against D. fragilis.

A case-controlled study of Dientamoeba fragilis infections in children.

Dientamoeba fragilis is a pathogenic protozoan parasite that is implicated as a cause of human diarrhoea. A case-controlled study was conducted to determine the clinical signs associated with D. fragilis infection in children presenting to a Sydney Hospital. Treatment options are also discussed. Stool specimens were collected from children aged 15 years or younger and analysed for the presence of D. fragilis. In total, 41 children were included in the study along with a control group. Laboratory diagnosis was performed by microscopy of permanently stained, fixed faecal smears and by real-time PCR. Gastrointestinal symptoms were present in 40/41 (98%) of these children with dientamoebiasis, with diarrhoea (71%) and abdominal pain (29%) the most common clinical signs. Chronic gastrointestinal symptoms were present in 2% of cases. The most common anti-microbial used for treatment was metronidazole (n=41), with complete resolution of symptoms and clearance of parasite occurring in 85% of cases. A treatment failure rate occurred in 15% of those treated with metronidazole. Follow-up treatment comprised of an additional course of metronidazole or iodoquinol was needed in order to achieve complete resolution of infection and symptoms in this group. This study demonstrates the pathogenic potential of D. fragilis in children and as such it is recommended that all laboratories must routinely test for this organism and treat if detected.