Blastocystis: Consensus of treatment and controversies

Sekar, Uma; Shanthi, M

doi:10.4103/2229-5070.113901

Cited by 51 publications

(35 citation statements)

References 31 publications

(67 reference statements)

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“…A recent review on antimicrobial treatments for Blastocystis suggested that TMP-SMX is a good alternative to metronidazole with fewer side effects and is more cost-effective (34). The review states that it is not known if TMP-SMX has a direct effect on Blastocystis or on the gut bacteria which are essential for Blastocystis survival.…”

Section: Discussionmentioning

confidence: 99%

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In Vitro Antimicrobial Susceptibility Patterns of Blastocystis

Roberts

Bush

Ellis

et al. 2015

Antimicrob Agents Chemother

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cBlastocystis is the most common human enteric protist with controversial clinical significance. Metronidazole is considered a first-line treatment for Blastocystis infection; however, there has been increasing evidence for the lack of efficacy of this treatment. Treatment failure has been reported in several clinical cases, and recent in vitro studies have suggested the occurrence of metronidazole-resistant strains. In this study, we tested 12 Blastocystis isolates from 4 common Blastocystis subtypes (ST1, ST3, ST4, and ST8) against 12 commonly used antimicrobials (metronidazole, paromomycin, ornidazole, albendazole, ivermectin, trimethoprim-sulfamethoxazole [TMP-SMX], furazolidone, nitazoxanide, secnidazole, fluconazole, nystatin, and itraconazole) at 10 different concentrations in vitro. It was found that each subtype showed little sensitivity to the commonly used metronidazole, paromomycin, and triple therapy (furazolidone, nitazoxanide, and secnidazole). This study highlights the efficacy of other potential drug treatments, including trimethoprim-sulfamethoxazole and ivermectin, and suggests that current treatment regimens be revised. Blastocystis is the most common enteric protist found in humans, with rates of infection ranging from 2% to 100% in developed and developing countries (1, 2). There have been 17 subtypes (STs) identified from humans and animals, with ST1 to ST9 identified in humans (3-5). ST3 is the predominant subtype found in most human studies (6-8). There have been numerous studies that have highlighted the clinical relevance of Blastocystis, and an association between subtype and symptoms has been made (9-12). Although the pathogenic potential of this parasite has long been documented, there is still debate on whether Blastocystis infections should be treated and, therefore, only a small number of studies have looked at treatment options for Blastocystis infection (13). Most case studies report first-line treatment with metronidazole and found various rates of efficacy with ranges of 0% to 100% (10, 14-16). Other antimicrobials that were used to treat Blastocystis infection included iodoquinol, ketoconazole, nitazoxanide, paromomycin, tinidazole, and trimethoprim-sulfamethoxazole (TMP-SMX), all with varied results (17-21). There have only been four previous studies to look at in vitro susceptibility patterns of Blastocystis, all of which have had a small number of study isolates. From these studies though, it is apparent that different subtypes show different susceptibility patterns and that metronidazole is not the most effective treatment for Blastocystis infection (22)(23)(24)(25). In this study, the in vitro susceptibility patterns of 12 different commonly used antiparasitics and antimicrobials (metronidazole, paromomycin, ornidazole, albendazole, ivermectin, trimethoprim-sulfamethoxazole, furazolidone, nitazoxanide, secnidazole, fluconazole, nystatin, and itraconazole) were examined against 12 clinical isolates of Blastocystis from four different subtypes (ST1, ST3, ST4, and ST8) run...

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Section: Discussionmentioning

confidence: 99%

“…The prescription of a triple drug therapy is becoming common practice by some physicians (using secnidazole, furazolidone, and nitazoxanide) (34). The premise behind a triple therapy is that the combination of three drugs will have the highest possible efficacy against the pathogen.…”

Section: Discussionmentioning

confidence: 99%

In Vitro Antimicrobial Susceptibility Patterns of Blastocystis

Roberts

Bush

Ellis

et al. 2015

Antimicrob Agents Chemother

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“…Blastocystis isolates were not sensitive to other tested herbs such as ginger, black pepper, and white cumin [77]. It has been established that probiotics such as Saccharomices boulardii are equally effective as a symptomatic treatment as metronidazole [13,78].…”

Section: Clinical Significance and Treatmentmentioning

confidence: 99%

Blastocystis Hominis: a Mysterious and Commonly Disregarded Parasite

Tasić

Milenković

Bujić³

et al. 2017

FU Med Biol

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Abstract. Blastocystis hominis (B. hominis) is an anaerobic, single-cell protozoan, commonly present in human and definitive characterization of Blastocystis spp. is possible at the molecular level only. The parasite is transferred by the fecal-oral route. A variety of hosts have been identified, and animal-to-human and vice versa transfers have been documented. The most common manifestations of the infection with the organism are diarrhea, abdominal pain, nausea, and bloating. This infection has also been associated with the irritable bowel syndrome (IBS), non-specific colitis

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“…Other treatment options for blastocystosis include antimicrobials such as, nitazoxanide, furazolidone and emetine, ketoconazole, tinidazole and even the probiotic Saccharomyces boulardii (Sekar and Shanthi, 2013;Stensvold et al, 2010;. To date there is little experimental data to verify the efficacy of the other drugs used for blastocystosis treatment either.…”

Section: Treatmentmentioning

confidence: 99%

“…Metronidazole is the mainstay of treatment for human intestinal protozoa and the first-line therapy for blastocystosis where therapy is required (Coyle et al, 2012;Sekar and Shanthi, 2013;Stensvold et al, 2010;Tan, 2004;.…”

Section: Treatmentmentioning

confidence: 99%

Investigating the suitability of dogs and pigs as animal models for blastocystosis

Wang¹

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Blastocystis is an ubiquitous intestinal protozoon with a controversial pathogenesis and can colonise a wide range of species including humans, mammals, birds and reptiles. In the literature these species are collectively referred to as "Blastocystis", and that will be the convention throughout this document as well. In humans, it has been linked with non-specific gastrointestinal signs, non-gastrointestinal signs such as urticaria and recently irritable bowel syndrome. Major hurdles to determining the clinical significance/pathogenesis of Blastocystis are diagnostic limitations as it is a morphologically and genetically diverse organism, poor understanding of host-parasite relationship and the lack of a representative model to fulfil Koch's postulates.The principal aim of the project was identifying a suitable candidate for modelling human blastocystosis. This was defined as being a natural host of Blastocystis, meaning that the species had a high prevalence of Blastocystis infection with a predominant host-adapted subtype/s (ST) and the ability to harbour STs in common with humans. Once a candidate was identified, host/parasite interactions (e.g. intestinal location and pathology of Blastocystis, mucosal immune response) would be characterised to determine if this was comparable to the human infection.Dogs were identified as promising candidates as, in Brisbane, Queensland they have been shown to have a high Blastocystis prevalence and can harbour similar STs as in-contact humans. We utilised Polymerase chain reaction (PCR) to investigate the molecular epidemiology of Blastocystis in dogs in different geographical regions. We found a prevalence of 2.5%, 1.3% and 24% in dogs from Brisbane, a Cambodian village and stray dogs from India respectively. Stray dogs in India carried a diverse range of STs including 1, 4, 5 and 6, while dogs from Brisbane and Cambodia only carried ST1 and ST2 respectively. These differences in Indian dogs compared to the Brisbane/Cambodia dogs could reflect a closer proximity of the dogs to humans and other animals and their faeces. We concluded that dogs are unlikely natural hosts for Blastocystis but rather are transiently and opportunistically infected with a diversity of STs.iii Blastocystis is commonly reported in pigs, with most harbouring ST5 or ST1 and zoonotic transmission of ST5 from pigs has been proposed, therefore they were chosen as the next candidate. We studied the molecular epidemiology of pigs in two different geographic/environmental settings and also if they were zoonotic reservoirs by testing incontact humans for Blastocystis. Utilising PCR, it was found that Blastocystis prevalence in pigs from Southeast Queensland (SEQ) intensive piggeries and a Cambodian village was 76.7% and 45.2%, respectively, with all positive pigs harbouring ST5. 7.1% of pigs harboured ST1 and/or ST3 in addition to ST5, which are the two most common STs in humans. A minority (13.9%) of SEQ piggery staff harboured ST5, which is otherwise rare in humans, indicating possible zoonotic/r...

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Blastocystis: Consensus of treatment and controversies

Cited by 51 publications

References 31 publications

In Vitro Antimicrobial Susceptibility Patterns of Blastocystis

In Vitro Antimicrobial Susceptibility Patterns of Blastocystis

Blastocystis Hominis: a Mysterious and Commonly Disregarded Parasite

Investigating the suitability of dogs and pigs as animal models for blastocystosis

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