Genotype analysis of Acanthamoeba isolated from human nasal swabs in the Philippines

OBJECTIVE

To analyze the genotypes of Acanthamoeba species isolated from human nasal swabs in the Philippines.

METHODS

Human nasal swabs were collected from two groups: a low exposure group composed of students of the University of the Philippines-Diliman and a high exposure group composed of laborers frequently exposed to garbage, soil and dust. After isolation using non-nutrient agar plate lawned with Escherichia coli and DNA extraction using Chelex-100 resin, the ASA.S1 region of the gene (Rns) coding for nuclear, small subunit ribosomal RNA of Acanthamoeba was amplified through polymerase chain reaction. Purified polymerase chain reaction products were then sequenced. Neighbor-joining, maximum parsimony, and maximum likelihood phylogenetic trees were then constructed.

RESULTS

In the low exposure group, 1 out of 70 (1.43%) students and 7 out of 110 (6.36%) in the high exposure group were culture-positive. Four soil samples were also obtained for comparison, all of which were tested culture-positive. Of the 12 Acanthamoeba isolates, only 9 were successfully sequenced. The basic local alignment search tool of the US National Center for Biotechnology Information was used to identify most similar sequences. Five isolates were identified as genotype T5, and 3 isolateds were genotype T4. Genotype T11 was also isolated from soil, the first to be reported in the Philippines.

CONCLUSIONS

Genotype T11 is a possible pathogenic strain and both T4 and T5 can be pathogenic to human, hence, healthy provisions, especially for high exposure groups, should be given more attention and reevaluated.

Trichomonas vaginalis induces cytopathic effect on human lung alveolar basal carcinoma epithelial cell line A549

Trichomonas vaginalis, the causative agent of trichomoniasis is generally known to inhabit the genitourinary tract. However, several case reports with supporting molecular and immunological identifications have documented its occurrence in the respiratory tract of neonates and adults. In addition, the reports have documented that its occurrence is associated with respiratory failures. The medical significance or consequence of this association is unclear. Thus, to establish the possible outcome from the interaction of T. vaginalis with lung cells, the cytopathic effects of the parasites were evaluated using monolayer cultures of the human lung alveolar basal carcinoma epithelial cell line A549. The possible effect of association of T. vaginalis with A549 epithelial cells was analyzed using phase-contrast, scanning electron microscopy and fluorescence microscopy. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), crystal-violet and TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling) assays were conducted for cytotoxicity testing. The results demonstrate that T. vaginalis: (1) adheres to A549 epithelial cells, suggesting a density-dependent parasite-cell association; (2) adherence on A549 is through flagella, membrane and axostyle; (3) causes cell detachment and cytotoxicity (50-72.4%) to A549 and this effect is a function of parasite density; and (4) induces apoptosis in A549 about 20% after 6 h of incubation. These observations indicate that T. vaginalis causes cytopathic effects on A549 cell. To date, this is the first report showing a possible interaction of T. vaginalis with the lung cells using A549 monolayer cultures. Further studies are recommended to completely elucidate this association.

Microbiological quality of fresh produce from open air markets and supermarkets in the Philippines

This study is the first in the Philippines to conduct a comprehensive assessment of the prevalence of bacterial pathogens and somatic phages in retailed fresh produce used in salad preparation, namely, bell pepper, cabbage, carrot, lettuce, and tomato, using culture and molecular methods. Out of 300 samples from open air and supermarkets, 16.7% tested positive for thermotolerant Escherichia coli, 24.7% for Salmonella spp., and 47% for somatic phages. Results show that counts range from 0.30 to 4.03 log10 CFU/g for E. coli, 0.66 to ≥ 2.34 log10 MPN/g for Salmonella spp., and 1.30 to ≥ 3.00 log 10 PFU/g for somatic phages. Statistical analyses show that there was no significant difference in the microbial counts between open air and supermarkets (α = 0.05). TaqMan and AccuPower Plus DualStar real-time polymerase chain reaction (RT-PCR) was used to confirm the presence of these organisms. The relatively high prevalence of microorganisms observed in produce surveyed signifies reduction in shelf-life and a potential hazard to food safety. This information may benefit farmers, consumers, merchants, and policy makers for foodborne disease detection and prevention.

Development of a loop-mediated isothermal amplification assay for detection of Trichomonas vaginalis

A loop-mediated isothermal amplification (LAMP) assay targeting the 2-kbp repeated DNA species-specific sequence was developed for detection of Trichomonas vaginalis, the causative agent of trichomoniasis. The analytical sensitivity and specificity of the LAMP assay were evaluated using pooled genital swab and urine specimens, respectively, spiked with T. vaginalis trophozoites. Genital secretion and urine did not inhibit the detection of the parasite. The sensitivity of the LAMP was 10-1000 times higher than the PCR performed. The detection limit of LAMP was 1 trichomonad for both spiked genital swab and urine specimens. Also, LAMP did not exhibit cross-reactivity with closely-related trichomonads, Trichomonas tenax and Pentatrichomonas hominis, and other enteric and urogenital microorganisms, Entamoeba histolytica, Candida albicans, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. This is the first report of a LAMP assay for the detection of T. vaginalis and has prospective application for rapid diagnosis and control of trichomoniasis.

Comparison of direct fecal smear microscopy, culture, and polymerase chain reaction for the detection of Blastocystis sp. in human stool samples

OBJECTIVE

To compare the sensitivity and specificity of direct fecal smear microscopy, culture, and polymerase chain reaction in the detection of Blastocystis sp. in human stool.

METHODS

Human stool samples were collected from a community in San Isidro, Rodriguez, Rizal, Philippines. These samples were subjected to direct fecal smear microscopy, culture and polymerase chain reaction to detect the presence of Blastocystis sp.

RESULTS

Of the 110 stool samples collected, 28 (25%) were detected positive for the presence of Blastocystis sp. by two or more tests. Culture method detected the highest number of Blastocystis-positive stool samples (n=36), followed by PCR of DNA extracted from culture (n=26), PCR of DNA extracted from stool (n=10), and direct fecal smear (n=9). Compared to culture, the sensitivity of the other detection methods were 66.7% for PCR from culture and 19.4% for both PCR from stool and direct fecal smear. Specificity of the methods was high, with PCR from culture and direct fecal smear having 97.3%, while PCR from stool at 95.9%.

CONCLUSIONS

In this study, in vitro culture is the best method for detecting Blastocystis sp. in human stool samples.

First report of Trichomonas tenax infections in the Philippines

Recent studies have reported Trichomonas tenax as a cause of pleuropulmonary infections in humans. In this study, sputum and vaginal swab samples were collected from patients suffering from respiratory ailments in Rodriguez, Rizal and sex workers attending the social hygiene clinics in Angeles City in Pampanga, Mandaluyong City and Pasay City in Metro Manila, Philippines, respectively. DNA was extracted from samples and the 18S rRNA gene was amplified and sequenced. Phylogenetic trees were constructed using neighbor-joining, maximum-likelihood, maximum parsimony, and Bayesian inference analyses. Results showed that the new primer sets successfully amplified T. tenax from 14 sputum samples and Trichomonas vaginalis from 19 vaginal swab samples. Consequently, all isolates clustered with high bootstrap support and posterior probability values to their respective reference strains in the phylogenetic tree. Thus, the genus Trichomonas formed a highly supported clade with T. vaginalis in the first clade and T. tenax in the second clade. These findings conclude that T. vaginalis is solely present in the genito-urinary tract of females and that T. tenax can be found in the respiratory tract of humans. To our knowledge, this is the first report of detection and identification of T. tenax from sputum samples in the Philippines. However, further studies are still needed to determine the pathogenicity of this organism in humans.

Diagnosis and molecular characterization of Trichomonas vaginalis in sex workers in the Philippines

Trichomonas vaginalis is a pathogenic protozoon which causes the sexually transmitted infection, trichomoniasis. The absence or non-specificity of symptoms often leads to misdiagnosis of the infection. In this study, 969 samples consisting of vaginal swabs and urine were collected and screened from social hygiene clinics across the Philippines. Of the 969 samples, 216 were used for the comparative analysis of diagnostic tools such as wet mount microscopy, culture, and PCR utilizing universal trichomonad primers, TFR1/2 and species-specific primers, TVK3/7 and TV1/2. PCR demonstrated higher sensitivity of 100% compared to 77% of the wet mount. PCR primer set TVK3/7 and culture had the same and the best expected average performance [receiver-operating characteristic (ROC): 0·98]. Prevalence of infection in the sample population was 6·8%.

Development of loop-mediated isothermal amplification for rapid detection of Entamoeba histolytica

OBJECTIVE

To develop a loop-mediated isothermal amplification (LAMP) assay for the detection of Entamoeba histolytica E. histolytica, the causative agent of amebiasis.

METHODS

The LAMP primer set was designed from E. histolytica hemolysin gene HLY6. Genomic DNA of E. histolytica trophozoites strain HK9 was used to optimize the LAMP mixture and conditions. Amplification of DNA in the LAMP mixture was monitored through visual inspection for turbidity of the LAMP mix as well as addition of fluorescent dye.

RESULTS

Positive LAMP reactions turned turbid while negative ones remained clear. Upon addition of a fluorescent dye, all positive reactions turned green while the negative control remained orange under ambient light. After electrophoresis in 1.5% agarose gels, a ladder of multiple bands of different sizes can be observed in positive samples while no bands were detected in the negative control. The sensitivity of the assay was found to be 5 parasites per reaction which corresponds to approximately 15.8 ng/μ L DNA. The specificity of the assay was verified by the absence of amplified products when DNA from other gastrointestinal parasites such as the morphologically similar but non-pathogenic species, Entamoeba dispar 39, and other diarrhea-causing organisms such as Blastocystis hominis and Escherichia coli were used.

CONCLUSIONS

The LAMP assay we have developed enables the detection of E. histolytica with rapidity and ease, therefore rendering it is suitable for laboratory and field diagnosis of amebiasis.

Molecular characterization of trichomonads isolated from animal hosts in the Philippines

Trichomonads are amitochondrial anaerobic flagellated protists that are either parasites or commensals, generally living in the digestive or genitourinary tract of humans and animals. It has been reported that these protozoa can migrate to other sites in their target host, can adapt to new hosts, and are capable of zoonotic transmission. In this study, 59 trichomonad isolates from different animal hosts in the Philippines were identified and characterized. Primer sets were designed and were successful in amplifying the 18S rRNA gene sequences of the isolates. Phylogenetic trees were constructed using neighbor-joining (NJ), maximum parsimony (MP), maximum-likelihood (ML) and Bayesian inference (BI) analyses. Results showed that BLAST analysis of the isolates corresponded to the clustering of the isolates together with reference sequences in the constructed ML tree. Cattle and pig isolates were most likely Tetratrichomonas buttreyi, which were observed to be commensal in both animals. All duck and rooster isolates were similar with Tetratrichomonas gallinarum. All dog isolates together with single isolates from boa, goat, and owl were identical to Pentatrichomonas hominis. Occurrence of P. hominis in Boa constrictor imperator (boa) and Otus megalotis (Philippine scops owl) suggested the adaptation of the trichomonad to new hosts. Reptile hosts were observed to harbor Trichomitus batrachorum or Hypotrichomonas acosta. Three reptile isolates (Igu2, Igu4, and Liz7) suggest novel species belonging to Class Hypotrichomonadea. Furthermore, iguanas were infected with T. batrachorum or H. acosta. Trichomonads in animal hosts are commensal and the mode of transmission is via fecal-oral route. They are capable of adaptation to new hosts and therefore, zoonotic transmission is possible as well as pathogenesis in host. Thus, trichomonads can pose threats to the health of humans and animals.

Antimicrobial activity, cytotoxicity, and phytochemical screening of Voacanga globosa (Blanco) Merr. leaf extract (Apocynaceae)

OBJECTIVE

To determine the antibacterial, antifungal, antiprotozoal, cytotoxic, and phytochemical properties of ethanol extracts of leaves of Voacanga globosa (Blanco) Merr. (V. globosa).

METHODS

The extracts were tested against bacteria and fungus through disc diffusion assay; against protozoa through growth curve determination, antiprotozoal and cytotoxicity assays.

RESULTS

The extract revealed antibacterial activities, inhibiting the growth of Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Micrococcus luteus, and Salmonella typhimurium. Antifungal assay showed that it inhibited Candida albicans. The antiprotozoal assay against Trichomonas vaginalis and Entamoeba histolytica showed that V. globosa can inhibit the parasites, wherein the action can be comparable to metronidazole. With the in situ cell death detection kit, Trichomonas vaginalis and Entamoeba histolytica exposed to V. globosa leaf extract was observed to fluoresce simultaneously in red and yellow signals signifying apoptotic-like changes. Preliminary phytochemical screening revealed the chemical composition of plant extract containing alkaloids, saponins, 2-deoxysugars, and hydrolysable tannins.

CONCLUSIONS

Thus, this study provides scientific evidence on the traditional use of V. globosa leaf extract in treating microbial diseases. Further, the leaf extract can possibly be used to produce alternative forms of antimicrobials.

Profiles of Entamoeba histolytica-specific immunoglobulins in human sera

OBJECTIVE

To determine the profiles of anti-Entamoeba histolytica (E. histolytica) IgA, IgG, and IgM in sera of diarrheic and non-diarrheic individuals and partially characterize target antigens.

METHODS

Serum samples from thirty diarrheic and thirty non-diarrheic individuals were subjected to IgA, IgG, and IgM profiling through enzyme-linked immunosorbent assay (ELISA), flow cytometry, and immunoblot.

RESULTS

ELISA titer results showed that both diarrheic and non-diarrheic individuals possess high levels of E. histolytica-specific IgG compared to IgA and IgM. Flow cytometry data showed that diarrheic serum samples had higher mean reaction percentages against E. histolytica cells compared to non-diarrheic samples. Immunoreactive E. histolytica proteins with molecular weights ranging between 7 kDa and 292 kDa were recognized by diarrheic serum IgG, and 170 kDa and 250 kDa by non-diarrheic serum IgG.

CONCLUSIONS

Our findings suggest that serum anti-E. histolytica IgG, compared with serum anti-E. histolytica IgA and IgM responses, was generally high in both diarrheic and non-diarrheic sera, indicating a past exposure to the organism both in symptomatic patients as well as in asymptomatic carriers, respectively. In addition, serum IgG from diarrheic and non-diarrheic patients were able to detect immunogenic E. histolytica proteins.

Tannin-rich fraction from Terminalia catappa inhibits quorum sensing (QS) in Chromobacterium violaceum and the QS-controlled biofilm maturation and LasA staphylolytic activity in Pseudomonas aeruginosa

AIM OF THE STUDY

The study aimed to test the activity of Terminalia catappa L. against bacterial quorum sensing (QS) in order to provide a potential scientific basis for the traditional use of leaf extracts of this plant as an antiseptic.

MATERIALS AND METHODS

The anti-QS activity of the methanolic leaf extract of Terminalia catappa was detected through the inhibition of the QS-controlled violacein pigment production in Chromobacterium violaceum. Fractions resulting from size-exclusion chromatography were assayed. The most active fraction was characterized through qualitative phytochemical detection methods. The effect of this fraction on known QS-controlled phenotypes in test strains was assessed.

RESULTS

The fraction with the highest activity (labeled as TCF12) was characterized to be tannin-rich. It specifically inhibited QS-controlled violacein production in Chromobacterium violaceum with 50% reduction achieved at 62.5 μg mL(-1) without significantly affecting growth up to about 962 μg mL(-1). The assessment of its effects on LasA activity of Pseudomonas aeruginosa ATCC 10145 found that the production of this virulence determinant is reduced in a concentration dependent manner with about 50% reduction at 62.5 μg mL(-1). Furthermore, it was found that TCF12 was able to inhibit the maturation of biofilms of Pseudomonas aeruginosa, a phenotype that has also been known to be QS-regulated.

CONCLUSION

Therefore, tannin-rich components of Terminalia catappa leaves are able to inhibit certain phenotypic expression of QS in the test strains used.

Evaluation of buffy coat 16S rRNA PCR, buffy coat culture and whole blood PCR for detection of bacteraemia

The use of Gram type-specific PCR on buffy coat from clinical specimens for the detection of bacteraemia was evaluated for the first time using whole blood culture as the gold standard. In addition, the established buffy coat culture and whole blood PCR were also compared. Gram-positive bacteria belonging to six species and Gram-negative bacteria from 10 species were isolated and identified by culture and detected using broad-range 16S rDNA primers and Gram-specific primers. Data from the three methods all conferred very high sensitivity, specificity, positive and negative predictive values when compared to whole blood culture. The Kappa coefficients of agreement were 0.9819 (buffy coat PCR), 0.9458 (whole blood PCR) and 1.0 (buffy coat culture), which establishes their validity as alternative methods to routine blood culture in detecting bacteraemia. In addition, results showed that there was a direct correlation of WBC counts greater than 12,000 cells per mm(3) to the occurrence of bacteraemia as detected by the four methods (p < 0.05).

18S ribosomal DNA genotypes of Acanthamoeba species isolated from contact lens cases in the Philippines

This study was carried out to document the genotypes of Acanthamoeba present in contact lens cases from 50 randomly selected contact lens wearers living in Quezon City, Metro Manila, Philippines. Acanthamoeba species were isolated from eight (16%) in 50 contact lens cases examined. We analyzed partial 18S ribosomal DNA (Rns) sequences of the eight isolates and found that the sequence differences were sufficient to distinguish the genotypes. After the isolates were genotyped, using the Basic Local Alignment Search Tool program, their phylogenetic positions relative to known Acanthamoeba isolates were determined. The model-based (GTR+Gamma+Iota) neighbor-joining, maximum likelihood, and Bayesian inference analyses, as well as the non-model-based maximum parsimony analysis were used. Results showed that of the eight isolates, six were Rns genotype T5 while two were Rns genotype T4. This present study indicates that genotype T5 is also a common contaminant in contact lens storage cases.

Identification of the 18S-ribosomal-DNA genotypes of Acanthamoeba isolates from the Philippines

Cyst morphology has been commonly used to identify the free-living amoeba Acanthamoeba to subgenus level. A more accurate and consistent method, based on the sequence analysis of the gene coding for the amoeba's small-subunit ribosomal RNA (Rns), has, however, been developed. There have been no attempts to identify the Acanthamoeba genotypes circulating in the Philippines. In this study, therefore, the ASA.S1 region of the Rns gene from 17 Acanthamoeba isolates, collected from soil, water and contact-lens storage cases in different regions of the Philippines, was sequenced. After the isolates were genotyped, using the BLAST program, their phylogenetic positions relative to known Acanthamoeba isolates were determined. For this, the model-based (GTR + Gamma) neighbour-joining, maximum-likelihood and Bayesian-inference analyses and the non-model-based maximum-parsimony analysis were used. All but two of the isolates were identified as the T5 or T4 genotypes, which are probably common in soil, water and contact-lens cases across the Philippines. The only other genotypes identified were T15 (as a single isolate from a contact-lens case) and T3 (as a single soil isolate).

Phylogenetic analysis of Blastocystis isolates from animal and human hosts in the Philippines

To study the genetic diversity and cross-transmissibility of Blastocystis species in naturally infected hosts, 12 Blastocystis isolates from animal and human hosts in the Philippines were analyzed by sequencing the full-length small subunit ribosomal RNA (SSU rRNA) genes. Each sequence showed very high similarity (from 97% to 100%) to homologous sequences of other Blastocystis isolates reported previously. Phylogenetic analysis revealed that the 12 isolates were classified into 4 genetically distinct subtypes: 1, 2, 3, and 6. Results showed that Blastocystis subtypes 1, 2, and 3 were shared by isolates from varied hosts. This study confirms the remarkable heterogeneity of SSU rRNA gene among different Blastocystis isolates. The findings of this study agree with previous reports that the different Blastocystis subtypes have low host-specificity, comprising isolates from humans and various animal hosts. This study also suggests evidence for zoonotic transmission of the parasite and cross-transmissibility among heterogeneous hosts.

Genotyping of Giardia duodenalis isolates among residents of slum area in Manila, Philippines

Giardia duodenalis is a flagellated protist that causes gastrointestinal disease throughout the world. In the Philippines, study on G. duodenalis is limited. It is also believed that prevalence rates of this organism in the country are underestimated. In this study, stool samples from residents living in a slum area in Manila were collected. These were examined under microscopy for identification of common helminthic and protistan parasites. Results showed that 22.05% of 2,354 stool samples collected contained Giardia cysts. A fraction of samples (n = 133) positive for Giardia cysts were set aside. Genomic DNA was extracted from these samples and a polymerase chain reaction-restriction fragment length polymorphism procedure based on the organism's triose phosphate isomerase gene was utilized. This particular procedure is capable of distinguishing assemblages or genotypes within G. duodenalis. The highest identified assemblage was Assemblage B (86.47%). The two genotypes of Assemblage A were also detected. This is the first report on the identification of genotypes of G. duodenalis in the Philippines. The results of this study can serve as basis for future control and prevention of giardiasis and parasitism in the country.

Colony growth of Philippine isolates of Blastocystis hominis in simplified, soft agar medium

The agar-cloning technique of Blastocystis hominis has been observed in both solid and semisolid agar using Iscove's modified Dulbecco's medium. In this study, Philippine isolates of B. hominis were grown by pour-plate method in semisolid agar using Locke's solution. Inoculated plates contained 0.7% agar, 10% horse serum, and 0.1% sodium thioglycollate. Plates were incubated at 37 degrees C in a microaerophilic jar for 7-10 days. Biconvex disk-shaped colonies were seen abound at the bottom half of the medium. Colonies growing at the agar-glass interface were flat and consisted of thin layers of cells. From these colonies, large amoeboid cells were frequently seen on the periphery, whereas smaller cells were concentrated at the core. Analysis of the SSU rDNA genetically established the identity of the clones to be B. hominis. This is the first report on agar cloning of Blastocystis in a compound medium.

Prevalence and genetic diversity of Entamoeba histolytica in an institution for the mentally retarded in the Philippines

A total of 113 mentally retarded patients residing in a mental institution in Metropolitan Manila, Philippines, were screened for the presence of Entamoeba histolytica based on microscopy and polymerase chain reaction (PCR). Anti-E. histolytica antibodies were also screened in 97 serum samples collected using immunofluorescence antibody (IFA) test. Parasitological examination showed E. histolytica/Entamoeba dispar in 43 cases (38.05%), while PCR detected 74 cases (65.48%) positive for E. histolytica and 6 cases (5.30%) positive for E. dispar. Interestingly, these 6 samples were coinfected with E. histolytica. IFA test revealed that 80.41% (78/97) of the respondents possessed significant antibody titers for intestinal infection of E. histolytica. Of this number, there were 5 patients negative in IFA test but positive in PCR. The genetic diversity of E. histolytica isolates was also investigated by analyzing polymorphism in the serine-rich gene by nested PCR on DNA directly extracted from stool specimens. A combination of the nested PCR results and the AluI digestion of the PCR products examined yielded six distinct DNA banding patterns among the 74 stool isolates. An apparent clustering of E. histolytica strains was observed in patients living in different residential cottages of the institution. These results indicate the high prevalence of E. histolytica in an institution for the mentally retarded in the Philippines.

Serological detection of cryptosporidiosis among Filipino cancer patients

Information on cryptosporidiosis in the Philippines is limited. To date, the disease is not routinely diagnosed in the country's medical institutions. To this end, a total of 53 Filipino cancer patients were surveyed for cryptosporidiosis using an indirect immunofluorescent antibody test. Fifteen patients (28.3%) were found to be positive for antibodies against Cryptosporidium. This study contributes to a better understanding of the incidence of cryptosporidiosis in the country.

Molecular characterization of Blastocystis isolates in the Philippines by riboprinting

Extensive genomic polymorphism has been demonstrated among morphologically identical Blastocystis isolates. To this end, 32 Blastocystis isolates from the Philippines (12 from humans, 12 from pigs and 8 from chickens) were analyzed genetically by riboprinting or restriction fragment length polymorphism (RFLP) analysis of polymerase chain reaction (PCR) amplified small subunit rDNA. Three distinct riboprint patterns were observed from the HinfI digestion, while four patterns resulted from the RsaI digestion of Blastocystis SSU rDNA. Restriction fragment profiles between Blastocystis isolates from different hosts were generally different from each other. However, Blastocystis isolates within each host group were practically the same. Cluster analysis of the riboprint patterns revealed seven distinct groups of the Blastocystis isolates, including a zoonotic strain. These results demonstrate the genetic heterogeneity of Blastocystis in the Philippines and a support to the idea of the organism's zoonotic potential.

Detection of Entamoeba dispar DNA in macaque feces by polymerase chain reaction

We used the polymerase chain reaction (PCR) to determine the prevalence of Entamoeba histolytica and E. dispar in the wild population of macaque monkeys (Macaca fuscata) in Mt. Takasaki, Oita Prefecture, Japan. Of the 101 samples collected, 41 (42.57%) were found to be positive for E. dispar. However, no E. histolytica was detected from the collected samples. The results of this survey demonstrate the high prevalence of E. dispar in macaque monkeys in the study area. Moreover, they provide additional baseline information on naturally acquired infectious agents of macaque monkeys and offer an accurate tool for detection of E. histolytica and E. dispar, which are needed for biomedical research using nonhuman primate models.

Application of the polymerase chain reaction (PCR) in the epidemiology of Entamoeba histolytica and Entamoeba dispar infections

In this paper, we briefly summarize the latest information on the polymerase chain reaction (PCR) as an epidemiologic tool for Entamoeba histolytica and Entamoeba dispar infections. This method which employs DNA template directly extracted from formalin fixed stool specimens offers a good promise for an accurate and reliable epidemiology of the two species. The assay is, sensitive enough to detect as few as five cysts in the stool sample, rapid and selectively differentiates E. histolytica from E. dispar DNA from stool specimens without the need for prior cultivation.

Field study on the distribution of Entamoeba histolytica and Entamoeba dispar in the northern Philippines as detected by the polymerase chain reaction

We used the polymerase chain reaction (PCR) to study the distribution of Entamoeba histolytica and E. dispar in 1,872 individuals in 14 communities in the northern Philippines. Here we report a field study using a DNA extraction protocol from formalin-fixed stool specimens as previously reported. This assay detected 137 stools (7.318%) containing E. dispar and 18 stools (0.961%) containing E. histolytica. The most affected age group for E. histolytica/E. dispar infections were those 5-14 years of age. There was no significant difference in the sex distribution of E. histolytica, while in the case of E. dispar, a higher prevalence was observed in females (9.186%) than in males (5.731%) (P < 0.01). An apparent clustering of stool-positive cases of E. histolytica and E. dispar was also observed in the northern part of the study area. The results of this survey demonstrate that E. dispar is highly prevalent in the communities studied. Moreover, it offers promise for the PCR using DNA extracted from formalin-fixed stools as a sensitive epidemiologic tool for detecting E. histolytica and E. dispar infections.

Differentiation of Entamoeba histolytica and E. dispar DNA from cysts present in stool specimens by polymerase chain reaction: its field application in the Philippines

It has been established that two distinct species exist within what was originally known as Entamoeba histolytica. These are E. dispar and E. histolytica, for the nonpathogenic and pathogenic forms, respectively. Differentiation of these two organisms is of great clinical importance since they are morphologically indistinguishable and both forms can infect the human intestinal cavity to different degrees. A simple and rapid DNA-extraction method that can be used directly on formalin-fixed stool specimens has been developed. The extracted DNA was used for the identification of the species existing in the stools by polymerase chain reaction (PCR). A total of 72 randomly collected stool samples from the Philippines were analyzed. In all, 19 samples reacted with E. dispar primers, resulting in the expected 101-bp PCR products; however, none reacted with E. histolytica primers. Furthermore, sensitivity assay suggests that genomic DNA from as few as five cysts can be used as a template for PCR. These observations imply that the use of genomic DNA directly extracted from formalin-fixed stool specimens for PCR amplification is a useful tool for obtaining a sensitive and accurate diagnosis that can be applied even in epidemiology studies.