Impact Of pH On The Viability And Morphology Of Blastocystis Isolates

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Farah Haziqah, M.T.1,2, Chandrawathani, P.3, Douadi, B.1, Suresh, K.4, Wilson, J.J.5, Mohd Khalid, M.K.N.6,Rajamanikam, A.4, Lewis, J.W.7 and Mohd Zain, S.N.1*

1Institute of Biological Sciences, Faculty of Sciences, University of Malaya, 50603 Kuala Lumpur, Malaysia

2School of Biological Sciences, Universiti Sains Malaysia, 11800 Pulalu Pinang, Malaysia

3Disease Control Division, Ministry of Health, Level 3 Block E 10, Complex E, Precint 1,Federal Govenment Administrative Centre, 62590 Putrajaya, Malaysia

4Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia

5International College Beijing, China Agricultural University, Beijing, 100083, P. R. China

6Molecular Diagnostics and Protein Unit, Specialised Diagnostics Centre, Institute for Medical Research,Jalan Pahang, 50588 Kuala Lumpur, Malaysia

7School of Biological Sciences, Royal Hollaway, University of London, Egham, Surrey, TW20 OEX, UK*Corresponding author e-mail:

Abstract: Blastocystis sp. is ubiquitous in avian, mammalian and human hosts and propagatesin either neutral or slightly alkaline conditions within the host’s gastro-intestinal tract. Of thefew previous studies on this enteric protozoan parasite in feline and canine hosts, prevalencevalues have been shown to range between 0 to 70.8%. In view of the close associationbetween humans, and canine and feline hosts as companion animals, faecal samples of 180Felis catus and 82 Canis lupus, collected from Penang and Kuala Lumpur, Malaysia, wereinitially screened by in vitro cultivation followed by molecular characterization. No positiveisolates were identified in culture but in 12 feline samples DNA barcoding detected a zoonoticsubtype Blastocystis ST1 for the first time. Consequently, avian and human isolates, whichhad previously been successfully cultured, were used to investigate the impact of pH on theviability and morphology of Blastocystis sp. The use of Trypan blue showed that the numberof viable cells increased when exposed to pH 4 and a significant increase in viability occurredin pH values of 5 to 7. Development of Blastocystis cells in both isolates was suppressed inmedia less than pH 5 followed by the disappearance of viable cells from avian isolates inmore acidic media below pH 4. Morphologically at pH 4 cells from avian isolates were lessrounded, and with wrinkled / shrunken surfaces, than the more normal rounded cells fromhuman isolates. On the other hand, at values below pH 3, no viable cells in human isolateswere visible. The present findings therefore confirm that gastro-intestinal pH is an importantdeterminant of Blastocystis viability and consequently influences the epidemiology of infectionwithin avian, mammalian and human hosts.

Tropical Biomedicine 35(2): 501–510 (2018)

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Categories: 2018
Tags: Jurnal/Prosiding/Abstrak