No advantage for antibiotic treatment over placebo in Blastocystis hominis-positive children with recurrent abdominal pain

J Pediatr Gastroenterol Nutr. 2012 May;54(5):677-9. doi: 10.1097/MPG.0b013e31823a29a7.


Objective: The aim of the study was to investigate whether recurrent abdominal pain (RAP) in Blastocystis hominis-positive children can be treated successfully with trimethoprim-sulfamethoxazole (TMP/SMX).

Methods: From October 2004 to December 2008, all of the patients referred to the Division of Gastroenterology and Nutrition of the University Children's Hospital Zurich because of RAP and detection of B hominis in stool samples as the only pathological finding after a standard workup were offered to participate in the study. Patients were randomly assigned into 2 groups. TMP/SMX or placebo was given for 7 days in a double-blind, placebo-controlled manner. Pain index (PI) was measured with a visual analogue scale. Two weeks after completion of treatment, 3 stool samples were collected and patients were followed clinically. If B hominis was still present, metronidazole was given for 7 days.

Results: Forty patients were included; 37 finished the study (TMP/SMX n = 20, placebo n = 17). Mean PI declined from 7.1 to 3.6 for all of the patients, with a decrease from 6.9 to 4.1 in the TMP/SMX and 7.4 to 3.0 in the placebo group, irrespective of detection of B hominis after treatment. There was no statistically significant difference in PI reduction between the 2 groups. Metronidazole treatment led to a further PI decline from 3.7 to 1.9. Eradication rates were 35% (TMP/SMX) and 44% (metronidazole), compared with spontaneous clearance of 29% in the placebo group.

Conclusions: There is no advantage for TPM/SMX over placebo in the treatment of RAP in B hominis-positive children.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Abdominal Pain / microbiology
  • Abdominal Pain / physiopathology*
  • Abdominal Pain / prevention & control
  • Adolescent
  • Anti-Bacterial Agents / therapeutic use*
  • Blastocystis Infections / drug therapy*
  • Blastocystis hominis / drug effects*
  • Blastocystis hominis / pathogenicity
  • Child
  • Child, Preschool
  • Double-Blind Method
  • Feces / microbiology
  • Female
  • Humans
  • Male
  • Metronidazole / therapeutic use
  • Recurrence
  • Treatment Outcome
  • Trimethoprim, Sulfamethoxazole Drug Combination / therapeutic use*


  • Anti-Bacterial Agents
  • Metronidazole
  • Trimethoprim, Sulfamethoxazole Drug Combination