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

• Published in: Gut pathogens Vol. 6; no. 1; p. 34
• Main Authors: Nagel, Robyn, Bielefeldt-Ohmann, Helle, Traub, Rebecca
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 20-08-2014; BioMed Central
• Subjects: Abdomen; Antibiotics; Case studies; Cytokines; Drug therapy; Gastroenterology; Gene expression; Health aspects; Infections; Irritable bowel syndrome; Laboratories; Mortality; Parasites; Patient outcomes; Permeability; Studies; Queensland Australia; Therapy; Blastocystis; PCR; Irritable bowel syndrome
• ISSN: 1757-4749; 1757-4749
• DOI: 10.1186/s13099-014-0034-0

Blastocystis 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.
In 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.
Six (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.
Clearance 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.