Molecular Epidemiology and Drug Resistance Study of Entamoeba histolytica in Clinical Isolates from Tehran, Iran

Document Type : Original Article


1 Department of Microbiology, Rasht Branch, Islamic Azad University, Rasht, Iran

2 Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran

3 Department of Biology, Payamnoor University, Tehran, Iran

4 Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran


Amoebiasis is a disease caused by Entamoeba histolytica, a protozoan parasite. Metronidazole is known as the main drug used for patients suffering from Amoebiasis. Despite the lack of drug resistance in clinical samples, there are scattered reports that are based on the failure of treatment which show the increase of clinical drug resistance against metronidazole. Therefore, the aim of this study was to identify E. histolytica by culture and polymerase chain reaction methods, compare them, and assess drug resistance among clinical samples to E. histolytica. A total of 1990 samples were collected from patients with dysentery. Positive microscopic samples after staining by lugol’s iodine were cultured on biphasic culture medium (HSre+s). The drug sensitivity of clinical isolates and standard reference strain of E. histolytica (HM1:IMSS) was evaluated after exposure to various concentrations of metronidazole on the basis of mobility and tonality using 0.01% Eosin. A PCR method was applied to confirm the cultural results. Forty six out of 19990 samples and 41 out of 46 samples were positive for E. histolytica by microscopic and cultural methods, respectively. However, only 15 out of 46 samples were positive by PCR amplification using specific primers of E. histolytica genome. According to the results of Entamoeba growing in the cultures with difference metronidazole concentrations, no resistance was observed at the concentrations higher than 2 mg/ml. The present results indicate the high specificity of the molecular techniques against culture in specific mediums. It also suggests Entamoeba isolates in Iran does not seem resistant to the metronidazole antibiotic.


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