Displaying publications 1 - 20 of 28 in total

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  1. Ragavan ND, Govind SK, Chye TT, Mahadeva S
    Parasit Vectors, 2014;7:404.
    PMID: 25174569 DOI: 10.1186/1756-3305-7-404
    Blastocystis, is one of the most common human intestinal protozoan, which has many conflicting reports on its pathogenic role. Gut conditions which obviously varies in asymptomatic individuals, symptomatic and irritable bowel syndrome (IBS) patients in terms of gut flora, pH, osmotic pressure and water potentials could play an important role in its pathogenicity. The present study is the first study to investigate phenotypic characteristics of Blastocystis sp. ST3 isolated from asymptomatic, symptomatic and IBS isolates.
    Matched MeSH terms: Blastocystis Infections/parasitology*
  2. Tan TC, Suresh KG
    Parasitol. Res., 2006 Nov;99(6):737-42.
    PMID: 16816959
    The amoeboid form of Blastocystis hominis has been reported infrequently, and its morphological descriptions have yielded conflicting and confusing reports. In the present study, we used the amoeboid forms seen predominantly in symptomatic patients infected with Blastocystis to provide detailed descriptions on the fine surface structure and intracellular morphology. Scanning electron microscopy revealed the irregular shape of the amoeboid form, with an intercalated fibrillar structure and a highly convoluted surface with deep indentations and projected pseudopodia. Transmission electron microscopy showed the existence of two types of amoeboid forms of B. hominis in in vitro culture, one with a large central vacuole containing tiny electron-dense particles while the other contains multiple small vacuoles in the cytoplasm. A surface coat with varying thickness surrounded the amoeboid form, which also showed prominent, extended pseudopodia of varying shape. Irregularly shaped mitochondrion-like organelles with prominent cristae, lipid inclusions, and multiple vacuoles were frequently seen in close proximity with the pseudopodia. The characteristic nucleus with a crescentic band of electron-dense chromatin material was also seen.
    Matched MeSH terms: Blastocystis Infections/parasitology*
  3. Vennila GD, Suresh Kumar G, Khairul Anuar A, Rajah S, Saminathan R, Sivanandan S, et al.
    Parasitol. Res., 1999 Feb;85(2):162-4.
    PMID: 9934969
    The shedding pattern of the protozoan parasite, Blastocystis hominis, is investigated in man and in experimental animal infections. The shedding pattern of the vacuolar and cystic forms of Blastocystis hominis in infected individuals have been shown in the present study to be irregular. The study shows that there is marked fluctuation in the shedding of the parasite from day to day, varying from as high as 17 to 0 per x40 microscopic field. The cystic stages when estimated in 8 Blastocystis-infected individuals ranged from as high as 7.4x10(5) cysts per gram of stool to 0. The shedding of cystic and vacuolar forms observed over a period of 20 days in experimentally-infected Wistar rats were not only shown to be irregular but the amount varied from host to host. The study has important diagnostic implications in that the stool samples must be collected more than once from patients showing clinical signs and symptoms to eliminate the cause of it to Blastocystis. The study also shows that there are asymptomatic individuals who pass a large amount of cysts as such individuals should be treated to prevent transmission to others.
    Matched MeSH terms: Blastocystis Infections/parasitology
  4. Kumarasamy V, Roslani AC, Rani KU, Kumar Govind S
    Parasit Vectors, 2014;7:162.
    PMID: 24708637 DOI: 10.1186/1756-3305-7-162
    There have been previous studies associating microorganisms to cancer and with our recent findings of Blastocytsis antigen having a higher in vitro proliferation of cancer cells strengthens the suspicion. Collecting faecal samples alone to associate this parasite with cancer may not be accurate due to the phenomenon of irregular shedding and the possible treatment administrated to the cancer patients. Hence, this become the basis to search for an alternate method of sample collection. Colonic washout is an almost complete washed up material from colon and rectum which includes various microorganisms such as Blastocystis and other lodged material within the villi. The detection of parasite in colonic washouts will give a better reflection on the association between Blastocystis and CRC.
    Matched MeSH terms: Blastocystis Infections/parasitology*
  5. Ragavan ND, Govind SK, Chye TT, Mahadeva S
    Parasitol. Res., 2015 Aug;114(8):2999-3005.
    PMID: 25982571 DOI: 10.1007/s00436-015-4502-3
    Blastocystis is one of the most common gut parasites found in the intestinal tract of humans and animals. We have previously reported the irregular shedding of Blastocystis cysts in stools from infected patients. In the present study, we assess the factors influencing shedding patterns from a Blastocystis ST3-infected IBS patient. The stools samples were voluntarily submitted for examination for a period of 30 days from Blastocystis ST3-infected IBS patient. A questionnaire on the factors that could influence the shedding pattern of the cysts was designed to assess the following information: (a) the frequency of frequenting the toilet in a day, (b) the timing of frequenting the toilet, (c) the stool forms, (d) the type of mood the patient was in when frequenting the toilet and (e) food intake. A total of 79 stool samples were collected for 30 days. The highest number of cysts recorded when the patient visited the toilet three times a day was 22.2 × 10(6) cysts/g. Frequenting the toilet between 6 a.m. to 11.59 a.m. showed the highest number of cysts, i.e. 21.7 × 10(6) cysts/g. Semi-solid forms showed the highest cyst count, i.e. 2.00 × 10(6) cysts/g. Irregular shedding of cysts was seen in 10 out of 30 days where the widest range recorded on day 17 was between 0 to 1.2 × 10(6) cysts/g. The average daily cyst count on days of emotional fluctuations was from 0 to 5.13 × 10(6) cysts/g. In conclusion, the study confirms that there are factors influencing shedding patterns of Blastocystis, and these have important implications when it comes to diagnosis and transmission of the parasite.
    Matched MeSH terms: Blastocystis Infections/parasitology*
  6. Girish S, Kumar S, Aminudin N
    Parasit Vectors, 2015;8:332.
    PMID: 26082155 DOI: 10.1186/s13071-015-0942-y
    In the local Malaysian context, herbal plants such as Eurycoma longifolia (Tongkat Ali), Orthosiphon stamineus (MisaiKucing), Ficus deltoidea (Mas Cotek), Zingiber officinale (Halia Bara) and Barringtonia racemosa (Putat) are known and widely used for its therapeutic properties. The first part of this study aims to screen for the anti-protozoal activity of these herbal plant extracts against Blastocystis sp. isolate subtype (ST) 3. Herbal extract with the highest efficacy was further fractionized into water and ethyl acetate fractions and tested against ST1, ST3 and ST5 Blastocystis sp. isolates. These isolates were also exposed to allopathic drugs, Metronidazole (MTZ), Tinidazole, Trimethoprim-sulfamethoxazole(TMP-SMX), Ketoconazole and Nitazoxanide for comparison purpose.
    Matched MeSH terms: Blastocystis Infections/parasitology
  7. Chandrasekaran H, Govind SK, Panchadcharam C, Bathmanaban P, Raman K, Thergarajan G
    Parasit Vectors, 2014;7:469.
    PMID: 25358755 DOI: 10.1186/s13071-014-0469-7
    Blastocystis sp., a widely prevalent intestinal protozoan parasite is found in a wide range of animals, including humans. The possibility of zoonotic transmission to human from birds especially ostriches led us to investigate on the cross infectivity of Blastocystis sp. isolated from the ostrich feces as well as the phenotypic and subtype characteristics. There is a need to investigate this especially with the rising number of ostrich farms due to the growing global ostrich industry.
    Matched MeSH terms: Blastocystis Infections/parasitology
  8. Tan TC, Suresh KG
    Parasitol. Res., 2007 Nov;101(6):1521-5.
    PMID: 17701428
    Blastocystis hominis has been regarded as an enigmatic parasite as many aspects of its basic biology remain uncertain. Many reproductive processes have been suggested for the organism; however, to date, only the binary fission has been proven. Plasmotomy is one of the modes of reproduction previously suggested to be seen in in vitro cultures. The present study provides trichrome and acridine orange staining evidence for the existence of nucleic acid suggestive of division of nucleus into multinucleate forms with the respective cytoplasm dividing giving rise to two or three progeny B. hominis. Transmission electron micrographs further confirmed that these daughter cells had respective surrounding surface coat, mitochondria, and vacuoles.
    Matched MeSH terms: Blastocystis Infections/parasitology
  9. Suresh K, Smith HV, Tan TC
    Appl. Environ. Microbiol., 2005 Sep;71(9):5619-20.
    PMID: 16151162
    Blastocystis cysts were detected in 38% (47/123) (37 Scottish, 17 Malaysian) of sewage treatment works. Fifty percent of influents (29% Scottish, 76% Malaysian) and 28% of effluents (9% Scottish, 60% Malaysian) contained viable cysts. Viable cysts, discharged in effluent, provide further evidence for the potential for waterborne transmission of Blastocystis.
    Matched MeSH terms: Blastocystis Infections/parasitology
  10. Tan TC, Suresh KG
    Parasitol. Res., 2006 Feb;98(3):189-93.
    PMID: 16323025
    Blastocystis hominis is one of the most common human parasites that inhabit the intestinal tract. Conflicting reports continue to exist regarding the existence and the functional role of the amoeboid forms in the life cycle of the parasite. The present study investigates the presence of these forms in 20 isolates obtained from ten symptomatic and asymptomatic patients respectively. A total of 10,000 parasite cells per ml from each isolate were inoculated into three culture tubes each containing 3 ml of Jones' medium supplemented with 10% horse serum, incubated at 37 degrees C. The contents were examined daily for 10 days. Irregular and polymorphic amoeboid forms with multiple extended pseudopodia were observed in all isolates from symptomatic patients, while none of the isolates from asymptomatic patients showed the presence of the amoeboid forms. The amoeboid forms were initially noted on day 2 and the percentages increased from 2% to 28%, with peak percentages from day 3 to day 6. Transmission electron microscopy revealed two types of amoeboid forms; one containing a large central vacuole completely filled with tiny electron-dense granules, and the other which revealed multiple small vacuoles within the central body. The cytoplasm contained strands of electron-dense granules resembling rough endoplasmatic reticulum, which is suggestive of active protein synthesis. The surface coat of the amoeboid form surrounding the parasite showed uneven thickness. Acridine orange stained the central body yellow and the periphery orange, indicating activity at the level of nucleic acids. The amoeboid form could either be an indicator of pathogenicity of B. hominis, or the form likely to contribute to pathogenicity and be responsible for the symptoms seen in patients.
    Matched MeSH terms: Blastocystis Infections/parasitology*
  11. Rajah Salim H, Suresh Kumar G, Vellayan S, Mak JW, Khairul Anuar A, Init I, et al.
    Parasitol. Res., 1999 Dec;85(12):1032-3.
    PMID: 10599928
    The present study investigated whether people working closely with animals were at higher risk of getting infected with Blastocystis hominis. The prevalence of the parasite was determined in two population groups, i.e., animal handlers and normal healthy individuals who did not work with animals. In all, 105 stool samples were collected from animal handlers from 2 local research institutions, a local zoo, and a local abattoir and 163 stool samples were collected from normal healthy individuals residing in high-rise flats in the city. The in vitro culture method used in the study detected that 41% of 105 animal handlers and 17% of 163 flat-dwellers in the city were positive for Blastocystis. This statistically significant finding (P = 0.0000313) shows that people who work closely with animals do stand at risk of acquiring Blastocystis infection.
    Matched MeSH terms: Blastocystis Infections/parasitology
  12. Thergarajan G, Govind SK, Bhassu S
    Parasitol. Res., 2018 Jan;117(1):177-187.
    PMID: 29188368 DOI: 10.1007/s00436-017-5688-3
    Blastocystis sp. is known to be the most commonly found intestinal protozoan parasite in human fecal surveys and has been incriminated to cause diarrhea and abdominal bloating. Binary fission has been widely accepted as the plausible mode of reproduction for this parasite. The present study demonstrates that subjecting the parasites in vitro to higher temperature shows the proliferation of parasite numbers in cultures. Transmission electron microscopy was used to compare the morphology of Blastocystis sp. subtype 3 isolated from a dengue patient having high fever (in vivo thermal stress) and Blastocystis sp. 3 maintained at 41 °C (in vitro thermal stress) and 37 °C (control). Fluorescence stains like acridine orange (AO) and 4',6'-diamino-2-phenylindole (DAPI) were used to demonstrate the viability and nuclear content of the parasite for both the in vitro and in vivo thermal stress groups of parasites. Blastocystis sp. at 37 °C was found to be mostly vacuolar whereas the in vitro thermal stressed isolates at 41 °C were granular with electron dense material seen to protect the granules within the central body. Parasites of the in vivo thermal stressed group showed similar ultrastructure as the in vitro ones. AO and DAPI staining provided evidence that these granules are viable which develop into progenies of Blastocystis sp. These granular forms were then observed to rupture and release progenies from the mother cells whilst the peripheral cytoplasmic walls were seen to degrade. Upon exposure to high temperature both in vitro and in vivo, Blastocystis sp. in cultures show higher number of granular forms seen to be protected by the electron dense material within the central body possibly acting as a protective mechanism. This is possibly to ensure the ability to survive for the granules to be developed as viable progenies for release into the host system.
    Matched MeSH terms: Blastocystis Infections/parasitology
  13. Rajamanikam A, Govind SK
    Parasit Vectors, 2013;6(1):295.
    PMID: 24499467 DOI: 10.1186/1756-3305-6-295
    Blastocystis spp. are one of the most prevalent parasites isolated from patients suffering from diarrhea, flatulence, constipation and vomiting. It's pathogenicity and pathophysiology remains controversial to date. Protease activity and amoebic forms have been reported previously in symptomatic isolates but there has been no conclusive evidence provided to correlate the protease activity and any specific life cycle stage of the parasite thus far.
    Matched MeSH terms: Blastocystis Infections/parasitology*
  14. Suresh K, Venilla GD, Tan TC, Rohela M
    Parasitol. Res., 2009 Jun;104(6):1373-80.
    PMID: 19238443 DOI: 10.1007/s00436-009-1340-1
    Blastocystis from infected stools of a person who showed chronic symptoms of abdominal discomfort and diarrhea were examined over a 6-month period, using transmission electron microscopy, for the ultrastructural changes from vacuolar to cystic stage. The study confirms the irregular shedding phenomenon of the organism previously reported, and for the first time, records sequential changes in encystation in stools collected over a time period. The study also confirms the existence of a precystic stage which has an immature cell wall consisting of a layer of a homogenous electron-dense mass surrounding the cell which acts as a intermediatory stage between the vacuolar and cystic stage.
    Matched MeSH terms: Blastocystis Infections/parasitology*
  15. Init I, Foead AL, Fong MY, Yamazaki H, Rohela M, Yong HS, et al.
    PMID: 18613539
    Genomic DNA of Blastocystis isolates released into 0.1% Triton X-100 was suitable for amplification and yielded similar results as the genomic DNA extracted with standard kit. The specific B. hominis primers (BH1: GCT TAT CTG GTT GAT CCT GCC AGT and BH2: TGA TCC TTC CGC AGG TTC ACC TAC A) successfully produced the PCR product of about 1,770 bp with all the 7 Blastocystis isolates tested. The restriction fragment length polymorphism (RFLP) patterns yielded by 13 out of 25 restriction endonucleases showed that the 7 isolates could be grouped into 4 subgroups: subgroup-1 consisted of isolate C; subgroup-2 of isolates H4 and H7; subgroup-3 of isolates KP1, Y51 and M12; and subgroup-4 of isolate 27805. The differences between subgroups manifested as clear-cut RFLP patterns. A common band of 230 bp was revealed by Eco R1 in all the Blastocystis isolates tested. The band of about 180 bp was revealed by Alu I, differentiated symptomatic from asymptomatic isolates of this parasite, and might indicate the pathogenicity of this parasite.
    Matched MeSH terms: Blastocystis Infections/parasitology
  16. Nithyamathi K, Chandramathi S, Kumar S
    PLoS ONE, 2016;11(2):e0136709.
    PMID: 26914483 DOI: 10.1371/journal.pone.0136709
    BACKGROUND: One of the largest cross-sectional study in recent years was carried out to investigate the prevalence of intestinal parasitic infections among urban and rural school children from five states namely Selangor, Perak, Pahang, Kedah and Johor in Peninsula Malaysia. This information would be vital for school authorities to influence strategies for providing better health especially in terms of reducing intestinal parasitism.

    METHODS AND PRINCIPAL FINDINGS: A total of 3776 stool cups was distributed to 26 schools throughout the country. 1760 (46.61%) responded. The overall prevalence of intestinal parasitic infection in both rural and urban areas was 13.3%, with Blastocystis sp (10.6%) being the most predominant, followed by Trichuris trichiura (3.4%), Ascaris lumbricoides (1.5%) and hook worm infection (0.9%). Only rural school children had helminthic infection. In general Perak had the highest infection (37.2%, total, n = 317), followed by Selangor (10.4%, total, n = 729), Pahang (8.6%, total, n = 221), Kedah (6.2%, total, n = 195) and Johor (3.4%, total, n = 298). School children from rural schools had higher infection (13.7%, total, n = 922) than urban school children (7.2%, total, n = 838). Subtype (ST) 3 (54.3%) is the most predominant ST with persons infected with only ST1 and ST3 showing symptoms. Blastocystis sp infection significantly associated with low household income, low parent's education and presence of symptoms (p<0.05).

    CONCLUSION: It is critical that we institute deworming and treatment to eradicate the parasite especially in rural school children.

    Matched MeSH terms: Blastocystis Infections/parasitology
  17. Ragavan AD, Govind SK
    Parasitol. Res., 2015 Mar;114(3):1163-6.
    PMID: 25614298 DOI: 10.1007/s00436-014-4296-8
    Dientamoeba fragilis, a trichomonad parasite is usually found in the gastrointestinal tract of human, and it is known to be the cause for gastrointestinal disease. The parasite is globally distributed and mostly found in rural and urban areas. The parasite is found in humans and nonhuman primates such as the macaques, baboons, and gorillas. Often, the parasite is confused with another largely found organism in stools called Blastocystis sp. especially when seen directly under light microscopy on culture samples containing both parasites. Both sometimes are seen with two nuclei with sizes tending to be similar which complicates identification. Stools were collected fresh from nine previously diagnosed persons infected with D. fragilis who also were found to be positive for Blastocystis sp. Samples were then cultured in Loeffler's medium and were stained with Giemsa, iron hematoxylin, and modified Fields' (MF) stain, respectively. D. fragilis was differentiated from Blastocystis sp. when stained with MF stain by the presence of a thinner outer membrane with clearly demarcated nuclei in the center of the cell whilst Blastocystis sp. had a darker and thicker stained outer membrane with the presence of two nuclei. The staining contrast was more evident with modified Fields' stain when compared with the other two. The simplicity in preparing the stain as well as the speed of the staining procedure make MF stain an ideal alternate. The modified Fields' stain is faster and easier to prepare when compared to the other two stains. MF stain provides a better contrast differentiating the two organisms and therefore provides a more reliable diagnostic method to precisely identify one from the other especially when cultures show mixed infections.
    Matched MeSH terms: Blastocystis Infections/parasitology
  18. Dhurga DB, Suresh KG, Tan TC, Chandramathi S
    Trans. R. Soc. Trop. Med. Hyg., 2012 Dec;106(12):725-30.
    PMID: 23141370 DOI: 10.1016/j.trstmh.2012.08.005
    Previous studies have shown that apoptosis-like features are observed in Blastocystis spp., an intestinal protozoan parasite, when exposed to the cytotoxic drug metronidazole (MTZ). This study reports that among the four subtypes of Blastocystis spp. investigated for rate of apoptosis when treated with MTZ, subtype 3 showed the highest significant increase after 72h of in vitro culture when treated with MTZ at 0.1mg/ml (79%; p<0.01) and 0.0001mg/ml (89%; p<0.001). The close correlation between viable cells and apoptotic cells for both dosages implies that the pathogenic potential of these isolates has been enhanced when treated with MTZ. This suggests that there is a mechanism in Blastocystis spp. that actually regulates the apoptotic process to produce higher number of viable cells when treated. Apoptosis may not just be programmed cell death but instead a mechanism to increase the number of viable cells to ensure survival during stressed conditions. The findings of the present study have an important contribution to influence chemotherapeutic approaches when developing drugs against the emerging Blastocystis spp. infections.
    Matched MeSH terms: Blastocystis Infections/parasitology*
  19. Tan TC, Tan PC, Sharma R, Sugnaseelan S, Suresh KG
    Parasitol. Res., 2013 Jan;112(1):85-9.
    PMID: 22961236 DOI: 10.1007/s00436-012-3107-3
    Blastocystis sp. is a common intestinal parasite found in humans and animals. The possibility of zoonotic transmission to humans from livestock especially goats led us to investigate the genetic diversity of caprine Blastocystis sp. obtained from five different farms in Peninsular Malaysia. Moreover, there is a lack of information on the prevalence as well as genetic diversity of Blastocystis sp. in goat worldwide. Results showed that 73/236 (30.9 %) of the goats were found to be positive for Blastocystis infection. The most predominant Blastocystis sp. subtype was ST1 (60.3 %) followed by ST7 (41.1 %), ST6 (41.1 %), and ST3 (11.0 %) when amplified by PCR using sequenced-tagged site (STS) primers. Four farms had goats infected only with ST1 whereas the fifth showed mixed infections with multiple STs. The proximity of the fifth farm to human dwellings, nearby domesticated animals and grass land as opposed to a sterile captive environment in the first four farms may account for the multiple STs seen in the fifth farm. Since ST1, ST3, ST6 and ST 7 were previously reported in human infection worldwide in particular Malaysia, the potential of the zoonotic transmission of blastocystosis should not be disregarded. The implications of different farm management systems on the distribution of Blastocystis sp. STs are discussed.
    Matched MeSH terms: Blastocystis Infections/parasitology
  20. Init I, Mak JW, Top S, Zulhainan Z, Prummongkol S, Nissapatorn V, et al.
    PMID: 15115079
    The objective of this study was to characterize the polypeptides associated with cysts of Blastocystis hominis. This form is believed to be infective and plays a role in parasite resistance to anti-B. hominis drugs currently used for treatment of Blastocystis associated diarrhea. Cysts were induced through in vitro culture of the parasite in complete medium supplemented with bacterial extract with trypticase, metronidazole or doxycycline. SDS-PAGE analysis showed almost similar polypeptide patterns of parasite extracts obtained from in vitro cultured parasites before and after exposure with the three supplements. Polypeptide bands at 76, 58.5, 48, 45, 40, 38, 32, 25 and 22 kDa were constantly seen in all antigenic preparations and no specific cyst-associated polypeptide was present. However, on immunoblot analysis, 3 out of 16 blastocystosis human sera identified a cyst-associated polypeptide at 60 kDa in all parasite extracts prepared from cultures with the three supplements. In addition, there were associated morphological changes detected in these parasites stained with acridine orange and observed under fluorescence microscopy. Metronidazole induced cyst forms (reddish cells) as early as 12 hours post-exposure; more cyst production (with stronger immunoblot bands) occurred after 24 hours exposure. However, cysts rupture with release and destruction of B. hominis daughters cells occurred after 48 hours exposure. Doxycycline induced less cyst-like forms at 24 hours (weaker 60 kDa band) and less destruction of the cysts (60 kDa band still present at 72 hours post exposure). Bacterial extract and trypticase also induced cysts at 12 hours with increasing numbers up to 72 hours exposure (corresponding increase in intensity of 60 kDa band from samples harvested at 12 to 72 hours post exposure) without any sign of deleterious effect on the parasite.
    Matched MeSH terms: Blastocystis Infections/parasitology*
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