Dientamoeba fragilis An unusual intestinal pathogen

Butler, William P.

doi:10.1007/bf02088750

Cited by 34 publications

(17 citation statements)

References 14 publications

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“…Therefore, this study is not directly comparable to the current study. To our knowledge, no other studies report on the effect of eradication of D. fragilis in IBS patients, but clinical improvement of gastrointestinal symptoms other than IBS linked to eradication of D. fragilis have been described 24,31,44,45,47,[53][54][55][56][57][58][59][60] suggesting that at least in some individuals D. fragilis is pathogenic. Only two epidemiologic studies deal with the association between D. fragilis and IBS.…”

Section: Discussionmentioning

confidence: 99%

Treatment of Dientamoeba fragilis in Patients with Irritable Bowel Syndrome

Engsbro

Stensvold²,

Nielsen³

et al. 2012

The American Society of Tropical Medicine and Hygiene

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Abstract. 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.

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Section: Discussionmentioning

confidence: 99%

Treatment of Dientamoeba fragilis in Patients with Irritable Bowel Syndrome

Engsbro

Stensvold²,

Nielsen³

et al. 2012

The American Society of Tropical Medicine and Hygiene

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“…In all of these patients, large numbers of D. fragilis organisms were observed in the absence of any other pathogens. Numerous reports from many different parts of the world continued to substantiate the association of D. fragilis with clinical symptoms, principally abdominal pain, diarrhea, nausea, vomiting, and fatigue (1,3,12,27,32,53,92,113,114,143,146).…”

Section: Clinical Overviewmentioning

confidence: 99%

“…This is reflected in a variety of descriptions conferred on the organism, such as: "a neglected cause of diarrhea" (49), "an unusual intestinal pathogen" (12), "an emerging protozoal infection" (129), and "an enigma shrouded in the mysteries of clinical parasitology" (140). Jepps and Dobell (65) considered the nucleus of D. fragilis to be the characteristic feature of the organism, since they observed that the predominant form was binucleate, a feature which readily differentiated it from other human intestinal amebas.…”

Section: Introductionmentioning

confidence: 99%

Emerging from Obscurity: Biological, Clinical, and Diagnostic Aspects of Dientamoeba fragilis

2004

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Ever since its first description in 1918, Dientamoeba fragilis has struggled to gain recognition as a significant pathogen. There is little justification for this neglect, however, since there exists a growing body of case reports from numerous countries around the world that have linked this protozoal parasite to clinical manifestations such as diarrhea, abdominal pain, flatulence, and anorexia. A number of studies have even incriminated D. fragilis as a cause of irritable bowel syndrome, allergic colitis, and diarrhea in human immunodeficiency virus patients. Although D. fragilis is most commonly identified using permanently stained fecal smears, recent advances in culturing techniques are simplifying as well as improving the ability of investigators to detect this organism. However, there are limitations in the use of cultures since they cannot be performed on fecal samples that have been fixed. Significant progress has been made in the biological classification of this organism, which originally was described as an ameba. Analyses of small-subunit rRNA gene sequences have clearly demonstrated its close relationship to Histomonas, and it is now known to be a trichomonad. How the organism is transmitted remains a mystery, although there is some evidence that D. fragilis might be transmitted via the ova of the pinworm, Enterobius vermicularis. Also, it remains to be answered whether the two distinct genotypes of D. fragilis recently identified represent organisms with differing virulence

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“…Due to the propensity of this organism to cause chronic infection, it is essential that correct diagnosis occur promptly (3,4,7,9,13,17). Two genotypes of D. fragilis have been described by analysis of the small subunit rRNA gene (10,12,17,22), with only one predominant in Australia (17).…”

mentioning

confidence: 99%

“…Diagnosis of D. fragilis relies on direct visualization of the trophozoites in stained fixed fecal smears by light microscopy, as demonstration of the characteristic nuclear structure cannot be achieved in unstained fecal specimens (4). D. fragilis may be difficult to distinguish from nonpathogenic protozoa (9).…”

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confidence: 99%

Evaluation of Three Diagnostic Methods, Including Real-Time PCR, for Detection of Dientamoeba fragilis in Stool Specimens

et al. 2006

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Dientamoeba fragilis is a protozoan parasite of humans that infects the mucosa of the large intestine and is associated with gastrointestinal disease. We developed a 5 nuclease (TaqMan)-based real-time PCR assay, targeting the small subunit rRNA gene, for the detection of D. fragilis in human stool specimens and compared its sensitivity and specificity to conventional PCR and microscopic examination by a traditional modified iron-hematoxylin staining procedure. Real-time PCR exhibited 100% sensitivity and specificity.Dientamoeba fragilis is a pathogenic protozoan parasite, often more prevalent than Giardia intestinalis, which causes gastrointestinal disease in humans (5,7,9,17). Due to the propensity of this organism to cause chronic infection, it is essential that correct diagnosis occur promptly (3,4,7,9,13,17). Two genotypes of D. fragilis have been described by analysis of the small subunit rRNA gene (10,12,17,22), with only one predominant in Australia (17).Diagnosis of D. fragilis relies on direct visualization of the trophozoites in stained fixed fecal smears by light microscopy, as demonstration of the characteristic nuclear structure cannot be achieved in unstained fecal specimens (4). D. fragilis may be difficult to distinguish from nonpathogenic protozoa (9).The aim of this study was to develop a real-time PCR method that is rapid, highly sensitive, and specific for the detection of D. fragilis in fecal specimens. Results from the real-time assay were compared to those derived by a conventional PCR and microscopic examination using a traditional modified iron-hematoxylin staining procedure in order to determine the usefulness and practicality of this real-time PCR test.(This research was performed by Damien Stark in partial fulfillment for the degree of Ph.D. at University of Technology Sydney.)Entamoeba histolytica HM-1:IMSS (ATCC strain 30459) and Trichomonas vaginalis (ATCC strain F1623) were passaged in TYI-S-33 broth: genomic DNA was extracted from them using a QIAamp DNA minikit (QIAGEN, Hilden, Germany).Stool specimens used in this study were those submitted to St. Vincent's Hospital Department of Microbiology, Sydney, for investigation of diarrhea. Portions of all stool samples were fixed in sodium acetate-acetic acid-formalin and permanently stained using a modified iron-hematoxylin stain (Fronine, Australia) according to the manufacturer's recommendations. DNA was extracted from fresh fecal specimens (Ͻ24 h old) using a QIAamp DNA stool minikit (QIAGEN, Hilden, Germany) according to the manufacturer's protocol. To ensure we were using "best practice" for the preparation of DNA from stool specimens using this kit, we also evaluated a modification of the manufacturer's instructions (8) using four samples positive for D. fragilis by microscopy. As a control, these same samples were also extracted following the manufacturer's instructions, and the two sets of DNA were then tested with conventional and real-time PCR.The small subunit (SSU) rRNA genes from D. fragilis was amplified using the prime...

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Dientamoeba fragilis An unusual intestinal pathogen

Cited by 34 publications

References 14 publications

Treatment of Dientamoeba fragilis in Patients with Irritable Bowel Syndrome

Treatment of Dientamoeba fragilis in Patients with Irritable Bowel Syndrome

Emerging from Obscurity: Biological, Clinical, and Diagnostic Aspects of Dientamoeba fragilis

Evaluation of Three Diagnostic Methods, Including Real-Time PCR, for Detection of Dientamoeba fragilis in Stool Specimens

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