Isolate resistance of Blastocystis hominis to metronidazole

Trop Med Int Health. 1999 Apr;4(4):274-7. doi: 10.1046/j.1365-3156.1999.00398.x.


Isolates of Blastocystis hominis from infected immigrant workers from Indonesia, Bangladesh and infected individuals from Singapore and Malaysia were assessed for growth pattern and degree of resistance to different concentrations of metronidazole. Viability of the cells was assessed using eosin-brillian cresyl blue which stained viable cells green and nonviable cells red. The Bangladeshi and Singaporean isolates were nonviable even at the lowest concentration of 0.01 mg/ml, whereas 40% of the initial inoculum of parasites from the Indonesian isolate at day one were still viable in cultures with 1.0 mg/ml metronidazole. The study shows that isolates of B. hominis of different geographical origin have different levels of resistance to metronidazole. The search for more effective drugs to eliminate th parasite appears inevitable, especially since surviving parasites from metronidazole cultures show greater ability to multiply in subcultures than controls.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Infective Agents / pharmacology*
  • Bangladesh
  • Blastocystis Infections / drug therapy
  • Blastocystis Infections / parasitology*
  • Blastocystis hominis / drug effects*
  • Blastocystis hominis / growth & development
  • Colony Count, Microbial
  • Drug Evaluation, Preclinical
  • Drug Resistance
  • Emigration and Immigration
  • Feces / parasitology
  • Humans
  • Indonesia
  • Malaysia
  • Metronidazole / pharmacology*
  • Singapore
  • Time Factors


  • Anti-Infective Agents
  • Metronidazole