Clinical pilot study: efficacy of triple antibiotic therapy in Blastocystis positive irritable bowel syndrome patients

Abstract

BackgroundBlastocystis species are common human enteric parasites. Carriage has been linked to Irritable Bowel Syndrome (IBS). Treatment of Blastocystis spp. with antimicrobials is problematic and insensitive diagnostic methods and re-infection complicate assessment of eradication. We investigated whether triple antibiotic therapy comprising diloxanide furoate, trimethoprim/sulfamethoxazole and secnidazole (TAB) given to diarrhoea-predominant IBS (D-IBS) patients positive for Blastocystis would achieve eradication.MethodsIn a longitudinal, prospective case study 10 D-IBS Blastocystis-positive patients took 14 days of diloxanide furoate 500 mg thrice daily, trimethoprim/sulfamethoxazole 160/80 mg twice daily and secnidazole 400 mg thrice daily. Faecal specimens were collected at baseline, day 15 and 4 weeks after completion of TAB. Specimens were analysed using faecal smear, culture and polymerase chain reaction (PCR) of the 16 SSU rRNA. Patients kept a concurrent clinical diary.ResultsSix (60%) patients cleared Blastocystis spp. after TAB, including three who had failed previous therapy. Subtypes detected were ST3 (60%), ST4 (40%), ST1 (20%) and ST7, 8 (10%); four patients had mixed ST infections. Serum immunoglobulin A (IgA) levels were low in 40% of patients. Higher rates of Blastocystis clearance were observed in patients symptomatic for less than a year (Mann–Whitney, p = 0.032, 95% confidence) with no associations found with age, previous antibiotic therapy, faecal parasite load, ST, IgA level or clinical improvement.ConclusionsClearance of Blastocystis spp. was achieved with TAB in 60% of D-IBS patients, an improvement over conventional monotherapy. Higher clearance rates are needed to facilitate investigation of the relevance of this parasite in clinically heterogenous IBS.

Prevalence and genetic diversity of Blastocystis in family units living in the United States

“…Interestingly ST4, which is considered rare outside of Europe ) but has been detected in Australia (Nagel et al, 2014;Nagel et al, 2012), was not present in our dataset. However, this could be due to the low number of individuals that were positive for Blastocystis -further sampling of individuals from different regions is required to definitively establish the incidence and distribution of ST4 in the US.…”

Blastocystis in Health and Disease: Are We Moving from a Clinical to a Public Health Perspective?

“…Hence, for many decades, Blastocystis parasites been subject to mainly epidemiological research that has sought to identify links between colonization and development of symptoms. Randomized controlled treatment studies serving to identify any role for Blastocystis in disease, including alleviation of symptoms upon parasite eradication, are practically nonexistent, which is one of the reasons why no known effective strategy exists with regard to eliminating Blastocystis from the intestine (2,3). The pathogenic potential of Blastocystis remains controversial primarily due to the following reasons: (i) asymptomatic colonization is very common; (ii) evidence suggesting Blastocystis-induced pathogenicity has been inferred mainly from in vitro studies (some of which were reviewed in recent publications [4,5]), while pathogenicity remains to be robustly demonstrated in vivo; (iii) in contrast to the above-mentioned protozoa, no striking phenotypic virulence properties, such as the presence of flagella, lectins, or rhoptries, have been identified, and phagocytosis has been described only once (6); (iv) no Blastocystis-associated outbreaks have been verified; (v) only anecdotal evidence exists regarding clinical improvement upon Blastocystis eradication in patients with gastrointestinal symptoms; and (vi) when epidemiological studies are used for inferring hypotheses on the basis of the pathogenic status of enteric microorganisms, distinctions between endemically and intermittently exposed populations are rarely-if ever-made; such distinctions may be critical to understanding differences in symptom development in the event that host immune response plays a significant role in Blastocystis-associated disease.…”

Are Blastocystis species clinically relevant to humans?

“…have been shown to be present in pig faeces (Wang et al 2014b) and in both faeces and serum of infected humans (Mahmoud & Saleh 2003). Our previous pilot study demonstrated lower serum IgA levels in IBS patients positive for Blastocystis carriage than in other patient groups or healthy controls (Nagel et al 2014). …”

“…using DNA sequencing). A study participant was considered to be positive if any one of the tests was positive as described previously (Nagel et al 2014). …”

“…Patients presenting to the clinic with chronic diarrhoea from 09/04/2008 to 20/2/14 were assessed clinically (Nagel et al 2014). Forty consecutive, eligible symptomatic patients who had no other cause for symptoms identified and who fulfilled the Rome criteria for diarrhoea-predominant IBS (Longstreth et al 2006), namely symptoms of chronic abdominal pain, occurring frequently over the last 3 months, associated with defecation and the passage of predominantly loose stool, were enrolled in the study.…”