Is Acanthamoeba sp. normally found in the eyes? A study was carried out to establish the possibility of Acanthamoeba sp. as a part of the normal conjunctival flora. Conjunctiva swabbing were carried out in 286 healthy Orang Asli school children using sterile cotton swab. The swab was then inoculated onto non-nutrient agar (NN-A). Heat killed Escherichia coli that was used as food source for the growth of the amoebae was pipetted onto and away from the smear. The plates were incubated at 30 degrees C and examined daily using an inverted microscope for 14 days. Morphology of the trophozoites and cysts of the amoebae were used as the taxonomic criteria for identification. Positive-controls and negative-controls were done to check for the consistency of the technique used and monitoring of contamination respectively. None of the conjunctiva swab cultured was positive for Acanthamoeba sp. This finding may indicate that Acanthamoeba sp. is not part of normal conjunctival flora or conjunctiva swab is an insensitive technique to isolate the organism. However, a more extensive research is needed to investigate these possibilities.
Balamuthia mandrillaris is a protist pathogen that can cause encephalitis with a mortality rate of more than 95%. Early diagnosis followed by aggressive treatment is a pre-requisite for successful prognosis. Current methods for identifying this organism rely on culture and microscopy, antibody-based methods using animals, or involve the use of molecular tools that are expensive. Here, we describe the isolation of antibody fragments that can be used for the unequivocal identification of B. mandrillaris. B. mandrillaris-specific antibody fragments were isolated from a bacteriophage antibody display library. Individual clones were studied by enzyme-linked immunosorbent assay, and immunofluorescence. Four antibody clones showed specific binding to B. mandrillaris. The usefulness of phage antibody display technology as a diagnostic tool for isolating antibody fragments against B. mandrillaris antigens and studying their biological role(s) is discussed further.
Acanthamoeba spp. are protist pathogens and causative agents of serious infections including keratitis and granulomatous amoebic encephalitis. Its ability to convert into dormant and highly resistant cysts form limits effectiveness of available therapeutic agents and presents a pivotal challenge for drug development. During the cyst stage, Acanthamoeba is protected by the presence of hardy cyst walls, comprised primarily of carbohydrates and cyst-specific proteins, hence synthesis inhibition and/or degradation of cyst walls is of major interest. This review focuses on targeting of Acanthamoeba cysts by identifying viable therapeutic targets.
Infectious diseases are the leading cause of morbidity and mortality, killing more than 15 million people worldwide. This is despite our advances in antimicrobial chemotherapy and supportive care. Nanoparticles offer a promising technology to enhance drug efficacy and formation of effective vehicles for drug delivery. Here, we conjugated amphotericin B, nystatin (macrocyclic polyenes), and fluconazole (azole) with silver nanoparticles. Silver-conjugated drugs were synthesized successfully and characterized by ultraviolet-visible spectrophotometry, Fourier transform infrared spectroscopy, and atomic force microscopy. Conjugated and unconjugated drugs were tested against Acanthamoeba castellanii belonging to the T4 genotype using amoebicidal assay and host cell cytotoxicity assay. Viability assays revealed that silver nanoparticles conjugated with amphotericin B (Amp-AgNPs) and nystatin (Nys-AgNPs) exhibited significant antiamoebic properties compared with drugs alone or AgNPs alone (P
The term 'tropical' refers to the region of the Earth lying between the Tropic of Cancer and the Tropic of Capricorn. Located between these equatorial parallels demarcating the Torrid Zone are several underdeveloped and developing countries: Thailand, the Philippines, Malaysia, Singapore, Indonesia, southern India, Sri Lanka, Brazil, Cuba, Ethiopia, Sudan and Nigeria, to name but a few considered to be 'tropical'. The climate in most of these countries is characterized by high temperatures and high humidity. The tropical climate and general state of socio-economic underdevelopment in such countries provide an ideal environment for pathogenic organisms, their vectors and intermediate hosts to flourish. Furthermore, the cultural habits and educational background of the people living in such countries expose them to pathogens and, when these people become infected, they readily become reservoirs for, or carriers of, those organisms. Ultimately, the adverse socioeconomic conditions of underdeveloped countries impede attempts to eradicate or control tropical diseases.
A 27-year-old man presented with a two-week history of central colicky abdominal pain associated with loose stools. Further history revealed that he had been exposed to contaminated waters. Stool investigation by direct wet stool smears revealed the presence of Entamoeba histolytica and Blastocystis hominis cysts. A diagnosis of amoebiasis secondary to E. histolytica and concurrent B. hominis infestation was made. We would like to emphasise the importance of clinical history including recent travel to endemic areas. Any suspicion of parasitic infection should prompt the clinician to investigate. Early diagnosis and management would prevent serious complications associated with E. Histolytica infection.
Amoebiasis is a parasitic infection caused by the
intestinal protozoan Entamoeba histolytica, most
prevalent in developing countries. It results in 40,000 to
100,000 deaths each year from amoebic colitis and extra
intestinal infections. Amoebic liver abscess (ALA)
is the most common extra intestinal site of infection
with an incidence of between 3% and 9% of all cases of
amoebiasis. Ultrasound which has a sensitivity of more
than 90% for detecting ALA is highly recommended
as an initial investigation followed by serological
demonstration of circulating antibodies specific to
Currently, species-specific information on Entamoeba infections is unavailable in Malaysia and is restricted worldwide due to the re-description of pathogenic Entamoeba histolytica and non-pathogenic Entamoeba dispar and Entamoeba moshkovskii. Therefore, this cross-sectional study was conducted to provide the first known documented data on the true prevalence of these three species in western Malaysia using a molecular method. Another aim of this study was to determine the association of potential risk factors associated with each Entamoeba sp. A total of 500 stool samples from three Orang Asli tribes were randomly collected. The overall prevalence of E. histolytica, E. dispar and E. moshkovskii determined by microscopy was 18.6% (93/500). Molecular analysis revealed that while most Entamoeba-positive individuals were infected with E. dispar (13.4%), followed by E. histolytica (3.2%) and E. moshkovskii (1.0%), the present findings show low prevalence rates of mixed infections with E. histolytica and E. dispar (2%), E. dispar and E. moshkovskii (1.2%) and association infections of E. histolytica, E. dispar and E. moshkovskii (0.4%). Logistical regression analysis indicates that the dynamics of the transmission of the three Entamoeba spp. was different. Of six statistically significant variables observed in the univariate analysis, three were retained as significant risk factors for E. histolytica infection in the logistical regression model. These factors were (i) not washing hands after playing with soil or gardening (Odds ratio (OR)=4.7; 95% confidence level (CI)=1.38, 16.14; P=0.013), (ii) indiscriminate defecation in the river or bush (OR=5.7; 95% CI=1.46, 21.95; P=0.012) and (iii) close contact with domestic animals (OR=5.4; 95% CI=1.36, 2.51; P=0.017). However, subjects with family members who were infected with E. histolytica/E. dispar/E. moshkovskii (OR=3.8; 95 CI=2.11, 6.86; P<0.001) and those who consumed raw vegetables (OR=1.8; 95% CI=1.01, 3.23; P=0.047) were more likely to be infected with E. dispar. On the other hand, no associated factor was identified with E. moshkovskii infection. Nevertheless, diarrhoea (P=0.002) and other gastroenteritis symptoms (P<0.001) were only associated with E. histolytica infection. The present study provides new insight into the distribution and risk factors of E. histolytica, E. dispar and E. moshkovskii infections among Orang Asli communities in Malaysia. Identifying the different risk factors of E. histolytica and E. dispar infections will help in the planning specific strategies in the control and prevention of each infection in the communities. Moreover, it emphasises the need for molecular methods to determine the species-specific prevalence of Entamoeba spp.
Acanthamoeba sp. is a free-living amoeba known to cause chronic central nervous system infection or eye infection in humans. Many cases remain undetected for want of a good detection system. We report for the first time a rapid staining method to facilitate the identification of Acanthamoeba sp. using the modified Field's staining technique. A. castellanii, which was used in the present experiment, is maintained in our laboratory in mycological peptone medium (Gibco). The cultures were pooled together and smears were made on glass slides for staining purposes. Different types of stains such as Field's stain, modified Field's stain, Wright's stain, Giemsa stain, Ziehl-Neelsen stain, and trichrome stain were used to determine the best stain for the identification of this amoeba. The concentration of various stains and the duration of staining were varied to provide the best color and contrast for each stain. Acanthamoeba was also obtained from the brain of experimentally infected mice and was stained with various stains as mentioned above to determine the best stain for use in identifying the presence of this parasite in experimentally infected animals. The modified Field's stain gives a very good color contrast as compared with other stains. Furthermore, it takes only 20 s to be carried out using the least number of reagents, making it suitable for both laboratory and field use.
A hospital based retrospective study of amoebiasis was carried out for a ten-year period at the University Hospital, Kuala Lumpur. Of the 51 cases traced, 30 (59%) had amoebic dysentery, 20 (39%) were amoebic liver abscess (ALA) and one patient had both conditions. Entameoba histolytica trophozoites were identified in 13 (43%) of the amoebic dysenteric stools and 9 (30%) from biopsy. Of the 20 (39%) ALA cases, only one showed parasites in the stool and biopsy. Majority of the patients with dysentery were Malays while Chinese comprised 40% with ALA. Males predominated overall with a male female ratio of 3:1, while for ALA it was 9:1. Most of ALA were single (71.4%) and were localised in the right lobe. The majority of the patients were unemployed. Eighty three percent (83%) of the patients presented with diarrhoea or dysentery followed by abdominal pain while those with ALA had fever, chills, rigors and pain in the right hypochondrium. Eighty percent of the ALA cases showed hepatomegaly. All patients responded to treatment with metronidazole.
The free-living protozoan Acanthamoeba is an opportunistic pathogen that is ubiquitous in our environment. However, its role in affecting indoor air quality and ill-health of indoor occupants is relatively unknown. The present study investigated the presence of Acanthamoeba from the ventilation system and its correlation with other indoor air quality parameters, used in the industry code of practice and its potential as an indicator for indoor air quality. Indoor air quality assessments were carried out in nine commercial buildings with approval from the building management, and the parameters assessed were as recommended by the Department of Occupational Safety and Health. The presence of Acanthamoeba was determined through dust swabs from the ventilation system and indoor furniture. Logistic regression was performed to study the correlation between assessed parameters and occupants' complaints. A total of 107 sampling points were assessed and 40.2% of the supplying air diffuser and blowing fan and 15% of the furniture were positive for cysts. There was a significant correlation between Acanthamoeba detected from the ventilation system with ambient total fungus count (r=0.327; p=0.01) and respirable particulates (r=0.276; p=0.01). Occupants' sick building syndrome experience also correlated with the presence of Acanthamoeba in the ventilation system (r=0.361; p=0.01) and those detected on the furniture (r=0.290; p=0.01). Logistic regression showed that there was a five-fold probability of sick building syndrome among occupants when Acanthamoeba was detected in the ventilation system.
Acanthamoeba spp. and Balamuthia mandrillaris are causative agents of granulomatous amoebic encephalitis (GAE), while Naegleria fowleri causes primary amoebic meningoencephalitis (PAM). PAM is an acute infection that lasts a few days, while GAE is a chronic to subacute infection that can last up to several months. Here, we present a literature review of 86 case reports from 1968 to 2016, in order to explore the affinity of these amoebae for particular sites of the brain, diagnostic modalities, treatment options, and disease outcomes in a comparative manner.
Acanthamoeba is a free living protozoa that can cause keratitis and granulomatous amoebic encephalitis. Physiological characteristics of this amoeba are found to have a medical importance in which it can be related to the pathogenicity potential of the organism. This study was carried out to investigate the physiological characteristics of survivability during axenization. Six Acanthamoeba strains from three clinical isolates (HSB 1, HKL 48 and HKL 95) and three environmental isolates (PHS 2, PHS 11 and PHS 15) were used in this study. Axenization test was done by treating cysts with hydrochloric acid (3%) and Page saline containing Gentamicin (100 µg/ml). Cysts were then cultured into PYG enrich media, incubated at 30oC and the presence and proliferation of trophozoites of Acanthamoeba were observed. This study showed that PHS 15, HSB 1, HKL 48 and HKL 95 could be axenized but they have poor proliferation rate in PYG enrich media. The result showed that the difference between both clinical and environmental isolates was observed in two strains; PHS 2 and PHS 11. This indicates that there is a possibility that the physiological traits of strains from both isolates are the same and strains from the environment are able to show the pathogenic potential and capable of causing infection to human.
Amebiasis is one of the major causes of diarrhea in the developing countries and it can present with a wide range of gastrointestinal symptoms depending on the phase of infection. We described a case of 50 year-old male patient who presented with abdominal pain, diarrhea and vomiting. After right hemicolectomy for appendicular abscess with tumour over the ileum, histopathological examinations revealed numerous trophozoites of Entamoeba histolytica in a background of inflammations (Figure 1). Following resection of the ameboma, he received intravenous metronidazole treatment for total of two weeks duration.