Real-Time PCR for the Diagnosis of Acanthamoeba Genotype T4
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ABSTRACT:
SUBMITTER: Lamien-Meda A
PROVIDER: S-EPMC9325200 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Confirmation of Acanthamoeba keratitis by laboratory diagnosis is the first step in the treatment of this vision-threatening disease. Two real-time PCR TaqMan protocols (the Rivière and Qvarnstrom assays) were developed for the detection of genus-specific Acanthamoeba DNA but lacked clinical validation. We have adapted these assays for the Cepheid SmartCycler II system (i) by determining their real-time PCR limits of detection and amplification efficiencies, (ii) by determining their ability to detect trophozoites and cysts, and (iii) by testing a battery of positive and negative samples. We also examined the inhibitory effects of a number of commonly used topical ophthalmic drugs on real-time PCR. The results of the real-time PCR limit of detection and amplification efficiency of the Rivière and Qvarnstrom assays were 11.3 DNA copies/10 microl and 94% and 43.8 DNA copies/10 microl and 92%, respectively. Our extraction protocol enabled us to detect 0.7 Acanthamoeba cysts/10 microl and 2.3 Acanthamoeba trophozoites/10 microl by both real-time PCR assays. The overall agreement between the assays was 97.0%. The clinical sensitivity and specificity of both real-time PCR assays based on culture were 100% (7 of 7) and 100% (37 of 37), respectively. Polyhexamethylene biguanide was the only topical drug that demonstrated PCR inhibition, with a minimal inhibitory dilution of 1/640 and an amplification efficiency of 72.7%. Four clinical samples were Acanthamoeba culture negative and real-time PCR positive. Our results indicate that both real-time PCR assays could be used to diagnose Acanthamoeba keratitis. Polyhexamethylene biguanide can inhibit PCR, and we suggest that specimen collection occur prior to topical treatment to avoid possible false-negative results.
| S-EPMC2566128 | biostudies-literature
Project description:BackgroundAcanthamoeba genus is introduced as opportunistic and cosmopolitan parasite. Monkey and wistar rat are appropriate models for experimental study on Acanthamoeba infection. In this study Acanthamoeba spp. were isolated from hot spring (HS), windows dust (WD) and a corneal sample of keratitis patient (KP) and their pathogenicity surveyed by in vitro and in vivo tests.MethodsIsolates of Acanthamoeba were cultivated axenically for 12 months in PYG medium. Overall, 30 wistar rats, in 6 equal groups were used for developing experimental Acanthamoeba keratitis (AK) and Granulomatous Amoebic Encephalitis (GAE). The Keratitis and Granulomatous Encephalitis experiments were performed by intrastromal and intranasal inoculation of Acanthamoeba cysts, respectively. Pathogenicity of the three isolates was also evaluated by in vitro test using osmotolerance and temperature tolerance assays. Identification of genotypes were performed by PCR technique and sequencing.ResultNone of the isolates could perform AK and GAE in wistar rats, although all isolates were described as T4 genotype. Isolates obtained from KP and WD could grow only in 30 °C, but not in 37 °C and 40 °C. On the other hand, HS isolate grew in 30 °C and 37 °C but not in 40 °C. Moreover, all of isolate grew in 0.5 M mannitol but not in 1 M and 1.5 M.ConclusionT4 isolates with a long-term axenic culture and different factors related to host and parasite may play role in pathogenicity of these free-living amoebae.
| S-EPMC4266116 | biostudies-literature
Project description:Leishmaniasis is a vector-borne disease caused by many Leishmania species, which can infect both humans and other mammals. Leishmaniasis is a complex disease, with heterogeneous clinical manifestations ranging from asymptomatic infections to lesions at cutaneous sites (cutaneous leishmaniasis), mucosal sites (mucocutaneous leishmaniasis) or in visceral organs (visceral leishmaniasis), depending on the species and host characteristics. Often, symptoms are inconclusive and leishmaniasis can be confused with other co-endemic diseases. Moreover, co-infections (mainly with HIV in humans) can produce atypical clinical presentations. A correct diagnosis is crucial to apply the appropriate treatment and the use of molecular techniques in diagnosis of leishmaniasis has become increasingly relevant due to their remarkable sensitivity, specificity and possible application to a variety of clinical samples. Among them, real-time PCR (qPCR)-based approaches have become increasingly popular in the last years not only for detection and quantification of Leishmania species but also for species identification. However, despite qPCR-based methods having proven to be very effective in the diagnosis of leishmaniasis, a standardized method does not exist. This review summarizes the qPCR-based methods in the diagnosis of leishmaniasis focusing on the recent developments and applications in this field.
| S-EPMC5930967 | biostudies-literature
Project description:BackgroundThe diagnosis of schistosomiasis currently relies on microscopic detection of schistosome eggs in stool or urine samples and serological assays. The poor sensitivity of standard microscopic procedures performed in routine laboratories, makes molecular detection methods of increasing interest. The aim of the study was to evaluate two in-house real-time Schistosoma PCRs, targeting respectively S. mansoni [Sm] and S. haematobium [Sh] in excreta, biopsies and sera as potential tools to diagnose active infections and to monitor treatment efficacy.MethodsSchistosoma PCRs were performed on 412 samples (124 urine, 86 stools, 8 biopsies, 194 sera) from patients with suspected schistosomiasis, before anti-parasitic treatment. Results were compared to microscopic examination and serological assays (enzyme-linked immunosorbent assay (ELISA), indirect haemagglutination (HA) and Western Blot (WB) assay).ResultsCompared to microscopy, PCRs significantly increased the sensitivity of diagnosis, from 4% to 10.5% and from 33.7% to 48.8%, for Sh in urine and Sm in stools, respectively. The overall sensitivity of PCR on serum samples was 72.7% and reached 94.1% in patients with positive excreta (microscopy). The specificity of serum PCR was 98.9%. After treatment, serum PCR positivity rates slowly declined from 93.8% at day 30 to 8.3% at day 360, whereas antibody detection remained positive after 1 year.ConclusionSchistosoma PCRs clearly outperform standard microscopy on stools and urine and could be part of reference methods combined with WB-based serology, which remains a gold standard for initial diagnosis. When serological assays are positive and microscopy is negative, serum PCRs provide species information to guide further clinical exploration. Biomarkers such as DNA and antibodies are of limited relevance for early treatment monitoring but serum PCR could be useful when performed at least 1 year after treatment to help confirm a cured infection.
| S-EPMC6756557 | biostudies-literature
Project description:We report the case of a 76-year old Filipino male who presented with pain, redness, and blurring of vision of the right eye. Corneal scraping was done and sent to the St. Luke's Research and Biotechnology Group for detection and identification of the infectious agent. Morphological detection was performed by allowing the organism from the scraping to grow in 1.5% non-nutrient agar plate with heat-killed E. coli. Trophozoites with acanthopodia and double-walled cysts characteristic of Acanthamoeba were observed within the first and second week of observations, respectively. Molecular identification of the amoebae at the genus level based on the presence of Acanthamoeba-specific amplimer S1, ASA.S1 confirmed the morphological identification. Genotyping through sequence revealed that the organism belonged to T4, which is the genotype commonly present in the eye of keratitis patients.
| S-EPMC4253062 | biostudies-literature
Project description:During measles outbreaks, it is important to be able to rapidly distinguish between measles cases and vaccine reactions to avoid unnecessary outbreak response measures such as case isolation and contact investigations. We have developed a real-time reverse transcription-PCR (RT-PCR) method specific for genotype A measles virus (MeV) (MeVA RT-quantitative PCR [RT-qPCR]) that can identify measles vaccine strains rapidly, with high throughput, and without the need for sequencing to determine the genotype. We have evaluated the method independently in three measles reference laboratories using two platforms, the Roche LightCycler 480 system and the Applied Biosystems (ABI) 7500 real-time PCR system. In comparison to the standard real-time RT-PCR method, the MeVA RT-qPCR showed 99.5% specificity for genotype A and 94% sensitivity for both platforms. The new assay was able to detect RNA from five currently used vaccine strains, AIK-C, CAM-70, Edmonston-Zagreb, Moraten, and Shanghai-191. The MeVA RT-qPCR assay has been used successfully for measles surveillance in reference laboratories, and it could be readily deployed to national and subnational laboratories on a wide scale.
| S-EPMC5328441 | biostudies-literature
Project description:The genus Madurella comprising four species, M. fahalii, M. mycetomatis, M. pseudomycetomatis, and M. tropicana, represents the prevalent cause of eumycetoma worldwide. The four species are phenotypically similar and cause an invariable clinical picture, but differ markedly in their susceptibility to antifungal drugs, and epidemiological pattern. Therefore, specific identification is required for optimal management of Madurella infection and to reveal proper epidemiology of the species. In this study, a novel multiplex real-time PCR targeting the four Madurella species was developed and standardized. Evaluation of the assay using reference strains of the target and non-target species resulted in 100% specificity, high analytical reproducibility (R2 values >0.99) and a lowest detection limit of 3 pg target DNA. The accuracy of the real-time PCR was further assessed using biopsies from eumycetoma suspected patients. Unlike culture and DNA sequencing as gold standard diagnostic methods, the real-time PCR yielded accurate diagnosis with specific identification of the causative species in three hours compared to one or two weeks required for culture. The novel method reduces turnaround time as well as labor intensity and high costs associated with current reference methods.
| S-EPMC6986762 | biostudies-literature
Project description:We developed a real-time-PCR assay utilizing a molecular-beacon probe for the detection of Entamoeba histolytica and compared its sensitivity to stool antigen detection and traditional PCR. A total of 205 stool and liver abscess pus specimens from patients and controls were used for this purpose, 101 (49%) of which were positive by the TechLab E. histolytica-specific antigen detection test, while the other 104 (51%) stool and liver abscess pus specimens were negative by the antigen detection test. DNA was extracted from the stool and liver abscess pus specimens by the QIAGEN method and the small-subunit rRNA gene of E. histolytica and then amplified by traditional and real-time PCR. Out of these 205 stool and liver abscess pus specimens, 124 were positive by the real-time-PCR assay and 90 were positive by the traditional-PCR test. Compared to the real-time-PCR assay, the antigen detection test was 79% sensitive and 96% specific. When the traditional-PCR test results were compared to the real-time-PCR assay, the sensitivity of traditional PCR was 72% and the specificity was 99%. In conclusion, all three methods for the detection of E. histolytica were highly specific, with real-time PCR being the most sensitive.
| S-EPMC1153781 | biostudies-literature
Project description:Molecular identification of rare human infectious pathogens appears to be one of the most relevant current methods for rapid diagnosis and management of patients. PCR techniques, in particular real-time quantitative PCR, are best suited for the detection of DNA from the pathogens, even at low concentrations. Echinococcosis infections are due to helminths of the Echinococcus genus, with closely related species involved in parasitic lesions affecting animals and, accidentally, humans. We developed a multiplex qPCR (MLX qPCR) assay allowing for the detection of four Echinococcus species involved in Europe in alveolar echinococcosis (AE) and cystic echinococcosis (CE) (Echinococcus multilocularis, E. granulosus sensu stricto, E. ortleppi, and E. canadensis), based on short mitochondrial targets. A collection of 81 fresh and formalin-fixed paraffin-embedded tissues (FFPE) of AE and CE lesions was assembled. The qPCR assays were performed in triplex for Echinococcus spp. detection, associated with a qPCR inhibitor control. A duplex qPCR was also designed to enable diagnosis of two other dead-end helminthiases (cysticercosis (Taenia solium), and toxocariasis (Toxocara cati and T. canis)). The sensitivity of the qPCR was assessed and ranged from 1 to 5 × 10-4 ng/μL (seven PCR assays positive), corresponding to 37-42 cycles for quantifiable DNA. The specificity was 100% for all the targets. This multiplex qPCR, adapted to low amounts of DNA can be implemented in the laboratory for the rapid molecular diagnosis of Echinococcosis species.
| S-EPMC9886084 | biostudies-literature
Project description:Mycobacterium tuberculosis strains of the Beijing genotype were first identified in China and neighboring countries and have attracted special attention due to their global emergence and association with drug resistance. To further analyze the spread and special characteristics of Beijing genotype strains, accurate, rapid and sensitive methods that overcome the drawbacks of the classical methods such as IS6110 DNA fingerprinting or spoligotyping for the identification of strains of this genotype are needed. Based on the nucleotide sequences of M. tuberculosis SAWC0780 and H37Rv, primers and fluorogenic 5' nuclease (TaqMan) probes for real-time PCR assays specific for Beijing and non-Beijing strains, respectively, were designed. The detection limits for the real-time PCR assays were about 5 and 10 copies of chromosomal DNA, respectively. In mixtures of Beijing and non-Beijing DNA, a multiplex assay was able to detect (i) one copy of Beijing DNA in approximately 1,000 copies of non-Beijing DNA and (ii) one copy of non-Beijing DNA in approximately 2,000 copies of Beijing DNA. In a blinded analysis of a collection of 103 multidrug-resistant strains isolated in Germany in 2001, all 62 Beijing and all 41 non-Beijing strains were correctly identified. In conclusion, the real-time assay allows for the rapid and specific detection of Beijing and non-Beijing strains. The major advantages of this test in comparison to other methods used for the identification of Beijing strains are its simplicity and sensitivity and the fact that amplification and detection occur within one reaction tube.
| S-EPMC1392668 | biostudies-literature