Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-11 (of 11 Records) |
Query Trace: Steurer F[original query] |
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Detection and Differentiation of Leishmania spp. in Clinical Specimens Using a SYBR Green-Based Real-Time PCR Assay.
de Almeida ME , Koru O , Steurer F , Herwaldt BL , da Silva AJ . J Clin Microbiol 2016 55 (1) 281-290 Leishmaniasis in humans is caused by Leishmania spp. in the subgenera Leishmania and Viannia Species identification often has clinical relevance. Until recently, our laboratory relied on conventional PCR amplification of the Internal Transcribed Spacer 2 (ITS2) followed by sequencing analysis of the PCR product to differentiate Leishmania spp. Here we describe a novel real-time quantitative PCR (qPCR) approach based on SYBR green technology (LSG-qPCR), which uses genus-specific primers that target the ITS1 region and amplify DNA from at least 10 Leishmania spp., followed by melting temperature (Tm) analysis of the amplicons on qPCR platforms (Mx3000P qPCR System [Stratagene-Agilent] and 7500 Real-Time PCR System [ABI-Life Technologies]). We initially evaluated the assay by testing reference Leishmania isolates and comparing the results with those from the conventional ITS2-PCR approach. Then we compared the results from the real-time and conventional molecular approaches for clinical specimens from 1,051 patients submitted to our laboratory for Leishmania diagnostic testing: specimens from 477 patients tested positive for Leishmania spp. with the LSG-qPCR assay, 465 of which also tested positive with the conventional ITS2-PCR approach, 10 of which had positive results because of retesting prompted by LSG-qPCR positivity. On the basis of the Tm values of LSG-qPCR amplicons from reference and clinical specimens, we were able to differentiate four groups of Leishmania parasites: the Viannia subgenus in aggregate; the L. (L.) donovani spp. complex in aggregate; the species L. (L.) tropica; and the spp. L. (L.) mexicana, L. (L.) amazonensis, L. (L.) major, and L. (L.) aethiopica in aggregate. |
Perinatal screening for Chagas disease in southern Texas
Edwards MS , Rench MA , Todd CW , Czaicki N , Steurer FJ , Bern C , Montgomery SP . J Pediatric Infect Dis Soc 2015 4 (1) 67-70 Perinatal screening for Trypanosoma cruzi in a cohort of 4000 predominantly Hispanic women in southern Texas revealed that Chagas disease occurs with sufficient frequency (0.25%) that targeted perinatal screening should be considered to identify infected mothers and infants at risk for congenital infection. |
Prevalence and Impact of Chagas Disease Among Latin American Immigrants With Nonischemic Cardiomyopathy in Los Angeles, California
Traina MI , Sanchez DR , Hernandez S , Bradfield JS , Labedi MR , Ngab TA , Steurer F , Montgomery SP , Meymandi SK . Circ Heart Fail 2015 BACKGROUND: Chagas disease (CD) is a well-known cause of cardiomyopathy in Latin America, however, 300,000 individuals are estimated to have CD in the United States (US). This study examined the prevalence and impact of Chagas cardiomyopathy (CCM) in a US population. We hypothesized that patients with CCM would have increased morbidity and mortality as compared to patients with non-CCM. METHODS AND RESULTS: This is a single-center, prospective cohort study. Enrollment criteria were new diagnosis of non-ischemic CM (left ventricular ejection fraction ≤ 40%) and previous residence in Latin America for at least 12 months. Serologic testing for Trypanosoma cruzi was performed at enrollment. The primary end point was all-cause mortality or heart transplantation. The secondary end point was heart failure (HF)-related hospitalization. A total of 135 patients were enrolled, with a median of 43 months of follow-up. CD was diagnosed in 25 (19%) patients. The primary end point occurred in 9 patients (36%) in the CCM group and in 11 patients (10%) in the non-CCM group (hazard ratio [HR]: 4.46, 95% confidence interval [CI]: 1.8 to 10.8, p = 0.001). The secondary end point occurred in 13 patients (52%) in the CCM group and in 35 patients (32%) in the non-CCM group (HR: 2.22, 95% CI: 1.2 to 4.2, p = 0.01). CONCLUSIONS: There is a high prevalence of CD among Latin American immigrants diagnosed with non-ischemic CM in Los Angeles. Advanced CCM portends a poor prognosis and is associated with increased all-cause mortality/heart transplantation and HF-related hospitalization. |
Heart transplantation for Chagas cardiomyopathy in the United States
Kransdorf EP , Czer LS , Luthringer DJ , Patel JK , Montgomery SP , Velleca A , Mirocha J , Zakowski PC , Zabner R , Gaultier CR , Qvarnstrom Y , Benedict T , Steurer F , Bosserman E , Paddock CD , Rafiei M , Kobashigawa JA . Am J Transplant 2013 13 (12) 3262-8 Since an initial case in 2006, we noted multiple patients undergoing heart transplantation (HTx) for Chagas cardiomyopathy (CC) at our transplant program. The clinical characteristics, laboratory results and outcomes of patients with CC undergoing HTx in the United States have not been reported previously. In 2010, we implemented a systematic screening and management program for patients undergoing HTx for CC. Before HTx, all patients with idiopathic dilated cardiomyopathy who were born in a Chagas disease endemic country were screened for Trypanosoma cruzi (TC) infection with serology. After HTx, monitoring for TC reactivation was performed using clinical visits, echocardiography, endomyocardial biopsy and serial whole blood polymerase chain reaction (PCR) testing. Between June 2006 and January 2012, 11 patients underwent HTx for CC. One patient was empirically treated due to the presence of TC amastigotes in explanted cardiac tissue. Two patients experienced allograft dysfunction due to TC reactivation and three patients experienced subclinical reactivation (positive PCR results), which were treated. Chagas disease is a common cause of dilated cardiomyopathy in patients from endemic countries undergoing HTx at a transplant program in the United States. Reactivation is common after transplantation and can cause adverse outcomes. |
Chagas disease in Latin American immigrants with dilated cardiomyopathy in New York City
Kapelusznik L , Varela D , Montgomery SP , Shah AN , Steurer FJ , Rubinstein D , Caplivski D , Pinney SP , Turker D , Factor SH . Clin Infect Dis 2013 57 (1) e7 Chagas disease-associated cardiomyopathy is clinically similar to other causes of cardiomyopathy and, therefore, the diagnosis can be easily overlooked. We found a 13% point prevalence of Chagas disease in a sample of New York City immigrants with dilated cardiomyopathy. |
Genetic variation and exchange in Trypanosoma cruzi isolates from the United States.
Roellig DM , Savage MY , Fujita AW , Barnabe C , Tibayrenc M , Steurer FJ , Yabsley MJ . PLoS One 2013 8 (2) e56198 Trypanosoma cruzi, the causative agent of Chagas disease, is a multiclonal parasite with high levels of genetic diversity and broad host and geographic ranges. Molecular characterization of South American isolates of T. cruzi has demonstrated homologous recombination and nuclear hybridization, as well as the presence of 6 main genetic clusters or "discrete typing units" (DTUs). Few studies have extensively investigated such exchange events and genetic diversity in North American isolates. In the current study, we genetically characterized over 50 US isolates from wildlife reservoirs (e.g., raccoons, opossums, armadillos, skunks), domestic dogs, humans, nonhuman primates, and reduviid vectors from nine states (TX, CA, OK, SC, FL, GA, MD, LA, TN) using a multilocus sequencing method. Single nucleotide polymorphisms were identified in sequences of the mismatch-repair class 2 (MSH2) and Tc52 genes. Typing based on the two genes often paralleled genotyping by classic methodologies using mini-exon and 18S and 24Salpha rRNA genes. Evidence for genetic exchange was obtained by comparing sequence phylogenies of nuclear and mitochondrial gene targets, dihydrofolate reductase-thymidylate synthase (DHFR-TS) and the cytochrome oxidase subunit II- NADH dehydrogenase subunit I region (COll-ND1), respectively. We observed genetic exchange in several US isolates as demonstrated by incongruent mitochondrial and nuclear genes phylogenies, which confirms a previous finding of a single genetic exchange event in a Florida isolate. The presence of SNPs and evidence of genetic exchange illustrates that strains from the US are genetically diverse, even though only two phylogenetic lineages have been identified in this region. |
Sensitive and specific detection of Trypanosoma cruzi DNA in clinical specimens using a multi-target real-time PCR approach.
Qvarnstrom Y , Schijman AG , Veron V , Aznar C , Steurer F , da Silva AJ . PLoS Negl Trop Dis 2012 6 (7) e1689 BACKGROUND: The laboratory diagnosis of Chagas disease is challenging because the usefulness of different diagnostic tests will depend on the stage of the disease. Serology is the preferred method for patients in the chronic phase, whereas PCR can be successfully used to diagnose acute and congenital cases. Here we present data using a combination of three TaqMan PCR assays to detect T. cruzi DNA in clinical specimens. METHODS/PRINCIPAL FINDINGS: Included in the analysis were DNA extracted from 320 EDTA blood specimens, 18 heart tissue specimens, 6 umbilical cord blood specimens, 2 skin tissue specimens and 3 CSF specimens. For the blood specimens both whole blood and buffy coat fraction were analyzed. The specimens were from patients living in the USA, with suspected exposure to T. cruzi through organ transplantation, contact with triatomine bugs or laboratory accidents, and from immunosuppressed patients with suspected Chagas disease reactivation. Real-time PCR was successfully used to diagnose acute and Chagas disease reactivation in 20 patients, including one case of organ-transmitted infection and one congenital case. Analysis of buffy coat fractions of EDTA blood led to faster diagnosis in six of these patients compared to whole blood analysis. The three real-time PCR assays produced identical results for 94% of the specimens. The major reason for discrepant results was variable sensitivity among the assays, but two of the real-time PCR assays also produced four false positive results. CONCLUSIONS/SIGNIFICANCE: These data strongly indicate that at least two PCR assays with different performances should be combined to increase the accuracy. This evaluation also highlights the benefit of extracting DNA from the blood specimen's buffy coat to increase the sensitivity of PCR analysis. |
Identification of Leishmania spp. by molecular amplification and DNA sequencing analysis of a fragment of rRNA internal transcribed spacer 2.
de Almeida ME , Steurer FJ , Koru O , Herwaldt BL , Pieniazek NJ , da Silva AJ . J Clin Microbiol 2011 49 (9) 3143-9 Isoenzyme analysis of cultured parasites is the conventional approach for Leishmania species identification. Molecular approaches have the potential to be more sensitive and rapid. We designed polymerase chain reaction (PCR) generic primers to amplify a segment of the rRNA Internal Transcribed Spacer 2 (ITS2) from multiple Leishmania species. To validate the selected ITS2 fragment, we tested clinical specimens and compared the species results obtained by the molecular approach (PCR, followed by DNA sequencing analysis) with those from the parasitologic approach (in vitro culture, followed by isoenzyme analysis). Among the 159 patients with clinical specimens positive by both approaches, a total of 8 Leishmania species were identified. The species results were concordant for all but two patients: for one patient, the results were L. (Viannia) guyanensis by the molecular approach versus L. (V.) braziliensis by the parasitologic approach; for the other patient, the results were L. (Leishmania) tropica versus L. (L.) major, respectively. ITS2 PCR, followed by sequencing analysis, can be used to detect and discriminate among Leishmania species. The results confirmed our hypothesis that a region of the ITS2 gene can complement the characterization of Leishmania parasites at the species level. The approach we developed can be used as a diagnostic tool in reference laboratories with adequate infrastructure to perform molecular characterization of pathogens. |
Autonomic dysfunction and risk factors associated with Trypanosoma cruzi infection among children in Arequipa, Peru
Bowman NM , Kawai V , Gilman RH , Bocangel C , Galdos-Cardenas G , Cabrera L , Levy MZ , Cornejo Del Carpio JG , Delgado F , Rosenthal L , Pinedo-Cancino VV , Steurer F , Seitz AE , Maguire JH , Bern C . Am J Trop Med Hyg 2011 84 (1) 85-90 Chagas disease affects an estimated 8 million people in Latin America. Infected individuals have 20-30% lifetime risk of developing cardiomyopathy, but more subtle changes in autonomic responses may be more frequent. We conducted a matched case-control study of children in Arequipa, Peru, where triatomine infestation and Trypanosoma cruzi infection are emerging problems. We collected data on home environment, history, physical examination, electrocardiogram, and autonomic testing. Signs of triatomine infestation and/or animals sleeping in the child's room and household members with Chagas disease were associated with increased infection risk. Electrocardiogram findings did not differ between cases and controls. However, compared with control children, infected children had blunted autonomic responses by three different measures, the Valsalva maneuver, the cold pressor test, and the orthostatic test. T. cruzi-infected children show autonomic dysfunction, although the prognostic value of this finding is not clear. Sustained vector control programs are essential to decreasing future T. cruzi infections. |
Usefulness of PCR method for detection of Leishmania in Poland
Myjak P , Szulta J , de Almeida ME , da Silva AJ , Steurer F , Lass A , Pietkiewicz H , Nahorski WL , Goljan J , Knap J , Szostakowska B . Pol J Microbiol 2009 58 (3) 219-22 Leishmania parasites are the etiological agents of leishmaniosis, with severe course and often fatal prognosis, and the global number of cases has increased in recent decades. The gold standards for the diagnosis of leishmaniosis are microscopic examinations and culture in vitro of the different clinical specimens. The sensitivity of these methods is insufficient. Recent development in specific and sensitive molecular methods (PCR) allows for detection as well as identification of the parasite species (subspecies). The aim of the study was to estimate the usefulness of molecular methods (PCR) for detection of Leishmania species and consequently for the implementation of such methods in routine diagnostics of leishmaniosis in Polish patients returning from endemic areas of the disease. In our investigations we used 54 known Leishmania positive DNA templates (from culture and clinical specimens) received from the CDC (Atlanta, GA, USA). Moreover, 25 samples of bone marrow, blood or other tissues obtained from 18 Polish individuals suspected of leishmaniosis were also examined. In PCR we used two pairs of primers specific to the conserved region of Leishmania kinetoplast DNA (kDNA) minicircle (13A/13B and F/R). Using these primers we obtained amplicons in all DNA templates from the CDC and in three Polish patients suspected for Leishmania infection. In one sample from among these cases we also obtained positive results with DNA isolated from a blood specimen which was previously negative in microscopic examinations. |
Comparison of two immunochromatographic assays and the indirect immunofluorescence antibody test for diagnosis of Trypanosoma cruzi infection in dogs in south central Louisiana
Nieto PD , Boughton R , Dorn PL , Steurer F , Raychaudhuri S , Esfandiari J , Goncalves E , Diaz J , Malone JB . Vet Parasitol 2009 165 241-7 Two rapid tests evaluated in dogs considered to be of high risk of infection with the Chagas parasite Trypanosoma cruzi using two immunochromatographic assays: Trypanosoma Detect for canine, InBios, Seattle, WA and CHAGAS STAT-PAK assay, Chembio Diagnostic Systems, Medford, NY, in south central Louisiana. For this purpose a serological survey was carried out in a total of 122 dogs and a serum bank was created. These 122 animals were first tested by IFAT that was used as the standard test. From the serum bank 50 samples were tested using the two rapid Chagas assays and results compared to the standard test IFAT. The serological survey using IFAT showed a prevalence of T. cruzi infection in 22.1% of the tested dogs. In the immunochromatographic assays, 13 and 11 animals were positive on rapid assay: Trypanosoma Detect for canine, InBios and CHAGAS STAT-PAK, Chembio Diagnostic Systems, respectively compared to 11 positive by IFAT. These two immunochromatographic tests have shown high susceptibility and specificity compared to our standard method IFAT. The rapid, easy and accurate screening assays used in conjunction with confirmatory tests, would be an excellent tool for veterinarians to diagnose T. cruzi infection. Early detection of T. cruzi infection may prevent complications through an effective treatment. Greater awareness by veterinarians of the risk, clinical findings, history along with diagnostic methods will contribute greatly to an understanding of the true prevalence of Chagas disease in dogs in Louisiana. |
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