Parasitology Research

, Volume 115, Issue 1, pp 391–396 | Cite as

Increase number of mitochondrion-like organelle in symptomatic Blastocystis subtype 3 due to metronidazole treatment

  • Kalyani Raman
  • Suresh KumarEmail author
  • Tan Tian Chye
Original Paper


Blastocystis sp., an intestinal organism is known to cause diarrhea with metronidazole regarded as the first line of treatment despite reports of its resistance. The conflicting reports of variation in drug treatment have been ascribed to subtype differences. The present study evaluated in vitro responses due to metronidazole on ST3 isolated from three symptomatic and asymptomatic patients, respectively. Symptomatic isolates were obtained from clinical patients who showed symptoms such as diarrhea and abdominal bloating. Asymptomatic isolates from a stool survey carried out in a rural area. These patients had no other pathogens other than Blastocystis. Ultrastructural studies using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed drug-treated ST3 from symptomatic patients were irregular and amoebic with surface showing high-convoluted folding when treated with metronidazole. These organisms had higher number of mitochondrion-like organelle (MLO) with prominent cristae. However, the drug-treated ST3 from asymptomatic persons remained spherical in shape. Asymptomatic ST3 showed increase in the size of its central body with the MLO located at the periphery.


Blastocystis Metronidazole Amoeboid Subtype 3 Symptomatic Asymptomatic 



This work is supported by the High Impact Research Grant (HIR) (UM.C/HIR/MOHE/MED/44). The authors would like to thank the Department of Parasitology staff, Department of Transmission Electron Microscopy (TEM), Faculty of Medicine at the University of Malaya, Department of Scanning Electron Microscopy (SEM), Faculty of Science at the University of Malaya, and the Institute for Medical Research staff, Mr. Santhana for his assistance in the ultrastructural studies.

Author’s contribution

KR, SKG, and TTC were involved in all stages of the study, including the conception and designing of the experiment, data collection and analysis, and interpretation of results. KR wrote the manuscript, and all authors read and approved the finalized manuscript.

Compliance with ethical standards

Conflict of interest

The authors declare that the have no competing interests.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.Department of Parasitology, Faculty of MedicineUniversity of MalayaKuala LumpurMalaysia

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