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1.
Exp Parasitol ; 219: 108014, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33011238

RESUMEN

The objective set by WHO to reach elimination of human African trypanosomiasis (HAT) as a public health problem by 2020 is being achieved. The next target is the interruption of gambiense-HAT transmission in humans by 2030. To monitor progress towards this target, in areas where specialized local HAT control capacities will disappear, is a major challenge. Test specimens should be easily collectable and safely transportable such as dried blood spots (DBS). Monitoring tests performed in regional reference centres should be reliable, cheap and allow analysis of large numbers of specimens in a high-throughput format. The aim of this study was to assess the analytical sensitivity of Loopamp, M18S quantitative real-time PCR (M18S qPCR) and TgsGP qPCR as molecular diagnostic tests for the presence of Trypanosoma brucei gambiense in DBS. The sensitivity of the Loopamp test, with a detection limit of 100 trypanosomes/mL, was in the range of parasitaemias commonly observed in HAT patients, while detection limits for M18S and TgsGP qPCR were respectively 1000 and 10,000 trypanosomes/mL. None of the tests was entirely suitable for high-throughput use and further development and implementation of sensitive high-throughput molecular tools for monitoring HAT elimination are needed.


Asunto(s)
Técnicas de Diagnóstico Molecular/normas , Técnicas de Amplificación de Ácido Nucleico/normas , Reacción en Cadena en Tiempo Real de la Polimerasa/normas , Trypanosoma brucei gambiense/aislamiento & purificación , Tripanosomiasis Africana/prevención & control , Algoritmos , Animales , Recolección de Muestras de Sangre/métodos , Recolección de Muestras de Sangre/normas , ADN Protozoario/aislamiento & purificación , Ensayos Analíticos de Alto Rendimiento/métodos , Ensayos Analíticos de Alto Rendimiento/normas , Humanos , Ratones , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Sensibilidad y Especificidad , Manejo de Especímenes/métodos , Manejo de Especímenes/normas , Trypanosoma brucei gambiense/genética , Tripanosomiasis Africana/sangre , Tripanosomiasis Africana/diagnóstico
2.
Proteomics ; 19(16): e1800435, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-31241236

RESUMEN

Mass spectrometry-based proteomics has been extensively used to map bacterial proteomes, which has led to a better understanding of the molecular mechanisms underlying bacterial infection and bacteria-host interactions. Quantitative proteomics using selected or parallel reaction monitoring is considered one of the most sensitive and specific quantitative MS-based approaches and has significantly advanced proteome studies of pathogenic bacteria. Here, recent applications of targeted proteomics for bacteria identification, biomarker discovery, and the characterization of bacterial virulence and antimicrobial resistance are reviewed among others. Results of such studies are expected to further contribute to improve the fight against the most common human pathogenic bacteria.


Asunto(s)
Bacterias/metabolismo , Proteínas Bacterianas/metabolismo , Proteoma/metabolismo , Proteómica/métodos , Bacterias/patogenicidad , Infecciones Bacterianas/microbiología , Proteínas Bacterianas/análisis , Biomarcadores/análisis , Biomarcadores/metabolismo , Humanos , Espectrometría de Masas/métodos , Proteoma/análisis , Virulencia
3.
Clin Infect Dis ; 68(Suppl 2): S130-S137, 2019 03 07.
Artículo en Inglés | MEDLINE | ID: mdl-30845337

RESUMEN

BACKGROUND: This study gives an overview of a decade (2007-2017) of hospital-based Salmonella Typhi bloodstream infection (BSI) surveillance in the Democratic Republic of the Congo (DRC), at 4 main sampling sites. METHODS: Blood cultures were sampled in hospital-admitted patients with suspected BSI, according to standardized clinical indications. The results of the surveillance period 2015-2017 were compiled with those of previous surveillance periods (2007-2010 and 2011-2014). Whole genome sequencing of isolates with decreased ciprofloxacin susceptibility (DCS) was performed. RESULTS: Salmonella Typhi was isolated in 1.4% (531/37 388) and 10.3% (531/5177) of suspected and culture-confirmed BSI episodes, respectively. Salmonella Typhi ranked first among the BSI pathogens in adults (n = 220), but was mostly (n = 301 [56.7%]) isolated from children, of which 72.1% (217/301) and 31.6% (95/301) were <10 years and <5 years old, respectively. Multidrug resistance (MDR), DCS, and combined MDR/DCS were found in 38.3% (n = 180), 24.5% (n = 115), and 11.9% (n = 56) of 470 first isolates, respectively. MDR and DCS rates had increased since 2007, but remained stable during 2015-2017 with no geographical clustering at the province level. Most (91/93 [97.8%]) DCS isolates sequenced belonged to Genotyphi genotype 2.5.1, and gyr S83 was the most frequent DCS mutation (76/93 [81.7%]). Infections occurred perennially, but increased during the rainy season. CONCLUSIONS: Salmonella Typhi was a frequent cause of BSI in adults and children in DRC, with high rates of antibiotic resistance. Sustainable surveillance and implementation of vaccination are compelling.


Asunto(s)
Bacteriemia/epidemiología , Cultivo de Sangre , Monitoreo Epidemiológico , Salmonella typhi/aislamiento & purificación , Fiebre Tifoidea/epidemiología , Adolescente , Adulto , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Bacteriemia/microbiología , Niño , Preescolar , República Democrática del Congo/epidemiología , Farmacorresistencia Bacteriana Múltiple , Genotipo , Humanos , Lactante , Recién Nacido , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Salmonella typhi/efectos de los fármacos , Salmonella typhi/genética , Estaciones del Año , Factores de Tiempo , Adulto Joven
5.
Clin Infect Dis ; 65(7): 1229-1231, 2017 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-29136410

RESUMEN

We report a typhoid fever case with a Salmonella enterica serovar Typhi isolate showing extended spectrum ß-lactamase (ESBL) production in the Democratic Republic of the Congo. Whole genome sequencing revealed that the strain carried a plasmid-mediated CTX-M-15 ESBL gene and did not belong to the dominant H58 Salmonella Typhi clade.


Asunto(s)
Salmonella typhi/enzimología , beta-Lactamasas/metabolismo , Niño , República Democrática del Congo/epidemiología , Genoma Bacteriano/genética , Humanos , Masculino , Filogenia , Salmonella typhi/genética , Fiebre Tifoidea/epidemiología , Fiebre Tifoidea/microbiología , beta-Lactamasas/genética
6.
J Infect Dis ; 212(12): 1996-8, 2015 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-26080371

RESUMEN

To assess the efficacy of treatment for human African trypanosomiasis, accurate tests that can discriminate relapse from cure are needed. We report the first data that the spliced leader (SL) RNA is a more specific marker for cure of human African trypanosomiasis than parasite DNA. In blood samples obtained from 61 patients in whom human African trypanosomiasis was cured, SL RNA detection had specificities of 98.4%-100%, while DNA detection had a specificity of only 77%. Data from our proof-of-concept study show that SL RNA detection has high potential as a test of cure.


Asunto(s)
ADN Protozoario/análisis , Monitoreo de Drogas/métodos , ARN Lider Empalmado/análisis , Trypanosoma brucei gambiense/aislamiento & purificación , Tripanosomiasis Africana/tratamiento farmacológico , ADN Protozoario/genética , Humanos , ARN Lider Empalmado/genética , Sensibilidad y Especificidad , Trypanosoma brucei gambiense/genética
7.
PLoS Negl Trop Dis ; 17(6): e0011285, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-37327220

RESUMEN

Salmonella enterica serovar Typhi (S. Typhi) is the cause of typhoid fever, presenting high rates of morbidity and mortality in low- and middle-income countries. The H58 haplotype shows high levels of antimicrobial resistance (AMR) and is the dominant S. Typhi haplotype in endemic areas of Asia and East sub-Saharan Africa. The situation in Rwanda is currently unknown and therefore to reveal the genetic diversity and AMR of S. Typhi in Rwanda, 25 historical (1984-1985) and 26 recent (2010-2018) isolates from Rwanda were analysed using whole genome sequencing (WGS). WGS was locally implemented using Illumina MiniSeq and web-based analysis tools, thereafter complemented with bioinformatic approaches for more in-depth analyses. Whereas historical S. Typhi isolates were found to be fully susceptible to antimicrobials and show a diversity of genotypes, i.e 2.2.2, 2.5, 3.3.1 and 4.1; the recent isolates showed high AMR rates and were predominantly associated with genotype 4.3.1.2 (H58, 22/26; 84,6%), possibly resulting from a single introduction in Rwanda from South Asia before 2010. We identified practical challenges for the use of WGS in endemic regions, including a high cost for shipment of molecular reagents and lack of high-end computational infrastructure for the analyses, but also identified WGS to be feasible in the studied setting and giving opportunity for synergy with other programs.


Asunto(s)
Salmonella typhi , Fiebre Tifoidea , Humanos , Salmonella typhi/genética , Haplotipos , Antibacterianos/uso terapéutico , Rwanda , Fiebre Tifoidea/epidemiología , Secuenciación Completa del Genoma , Pruebas de Sensibilidad Microbiana
8.
Nat Commun ; 14(1): 3517, 2023 06 14.
Artículo en Inglés | MEDLINE | ID: mdl-37316492

RESUMEN

Antimicrobial resistant Salmonella enterica serovar Concord (S. Concord) is known to cause severe gastrointestinal and bloodstream infections in patients from Ethiopia and Ethiopian adoptees, and occasional records exist of S. Concord linked to other countries. The evolution and geographical distribution of S. Concord remained unclear. Here, we provide a genomic overview of the population structure and antimicrobial resistance (AMR) of S. Concord by analysing genomes from 284 historical and contemporary isolates obtained between 1944 and 2022 across the globe. We demonstrate that S. Concord is a polyphyletic serovar distributed among three Salmonella super-lineages. Super-lineage A is composed of eight S. Concord lineages, of which four are associated with multiple countries and low levels of AMR. Other lineages are restricted to Ethiopia and horizontally acquired resistance to most antimicrobials used for treating invasive Salmonella infections in low- and middle-income countries. By reconstructing complete genomes for 10 representative strains, we demonstrate the presence of AMR markers integrated in structurally diverse IncHI2 and IncA/C2 plasmids, and/or the chromosome. Molecular surveillance of pathogens such as S. Concord supports the understanding of AMR and the multi-sector response to the global AMR threat. This study provides a comprehensive baseline data set essential for future molecular surveillance.


Asunto(s)
Antibacterianos , Farmacorresistencia Bacteriana , Humanos , Antibacterianos/farmacología , Farmacorresistencia Bacteriana/genética , Etiopía/epidemiología , Genómica , Salmonella/genética
9.
Nat Commun ; 14(1): 6392, 2023 10 23.
Artículo en Inglés | MEDLINE | ID: mdl-37872141

RESUMEN

Invasive non-typhoidal Salmonella (iNTS) disease manifesting as bloodstream infection with high mortality is responsible for a huge public health burden in sub-Saharan Africa. Salmonella enterica serovar Typhimurium (S. Typhimurium) is the main cause of iNTS disease in Africa. By analysing whole genome sequence data from 1303 S. Typhimurium isolates originating from 19 African countries and isolated between 1979 and 2017, here we show a thorough scaled appraisal of the population structure of iNTS disease caused by S. Typhimurium across many of Africa's most impacted countries. At least six invasive S. Typhimurium clades have already emerged, with ST313 lineage 2 or ST313-L2 driving the current pandemic. ST313-L2 likely emerged in the Democratic Republic of Congo around 1980 and further spread in the mid 1990s. We observed plasmid-borne as well as chromosomally encoded fluoroquinolone resistance underlying emergences of extensive-drug and pan-drug resistance. Our work provides an overview of the evolution of invasive S. Typhimurium disease, and can be exploited to target control measures.


Asunto(s)
Infecciones por Salmonella , Salmonella typhimurium , Humanos , África del Sur del Sahara/epidemiología , Farmacorresistencia Microbiana , Genómica , Infecciones por Salmonella/epidemiología , Salmonella typhimurium/genética
10.
mBio ; 13(6): e0255322, 2022 12 20.
Artículo en Inglés | MEDLINE | ID: mdl-36354333

RESUMEN

Trypanosoma brucei gambiense is the primary causative agent of human African trypanosomiasis (HAT), a vector-borne disease endemic to West and Central Africa. The extracellular parasite evades antibody recognition within the host bloodstream by altering its variant surface glycoprotein (VSG) coat through a process of antigenic variation. The serological tests that are widely used to screen for HAT use VSG as one of the target antigens. However, the VSGs expressed during human infection have not been characterized. Here, we use VSG sequencing (VSG-seq) to analyze the VSGs expressed in the blood of patients infected with T. b. gambiense and compared them to VSG expression in Trypanosoma brucei rhodesiense infections in humans as well as Trypanosoma brucei brucei infections in mice. The 44 VSGs expressed during T. b. gambiense infection revealed a striking bias toward expression of type B N termini (82% of detected VSGs). This bias is specific to T. b. gambiense, which is unique among T. brucei subspecies in its chronic clinical presentation and anthroponotic nature. The expressed T. b. gambiense VSGs also share very little similarity to sequences from 36 T. b. gambiense whole-genome sequencing data sets, particularly in areas of the VSG protein exposed to host antibodies, suggesting the antigen repertoire is under strong selective pressure to diversify. Overall, this work demonstrates new features of antigenic variation in T. brucei gambiense and highlights the importance of understanding VSG repertoires in nature. IMPORTANCE Human African trypanosomiasis is a neglected tropical disease primarily caused by the extracellular parasite Trypanosoma brucei gambiense. To avoid elimination by the host, these parasites repeatedly replace their variant surface glycoprotein (VSG) coat. Despite the important role of VSGs in prolonging infection, VSG expression during human infections is poorly understood. A better understanding of natural VSG gene expression dynamics can clarify the mechanisms that T. brucei uses to alter its VSG coat. We analyzed the expressed VSGs detected in the blood of patients with trypanosomiasis. Our findings indicate that there are features of antigenic variation unique to human-infective T. brucei subspecies and that natural VSG repertoires may vary more than previously expected.


Asunto(s)
Trypanosoma brucei brucei , Tripanosomiasis Africana , Humanos , Animales , Ratones , Tripanosomiasis Africana/parasitología , Glicoproteínas Variantes de Superficie de Trypanosoma/genética , Trypanosoma brucei brucei/genética , Trypanosoma brucei gambiense/genética , Glicoproteínas de Membrana
11.
mBio ; 13(4): e0037422, 2022 08 30.
Artículo en Inglés | MEDLINE | ID: mdl-35862803

RESUMEN

Salmonella enterica serovar Typhimurium causes a devastating burden of invasive disease in sub-Saharan Africa with high levels of antimicrobial resistance. No licensed vaccine is available, but O-antigen-based candidates are in development, as the O-antigen moiety of lipopolysaccharides is the principal target of protective immunity. The vaccines under development are designed based on isolates with O-antigen O-acetylated at position C-2 of abequose, giving the O:5 antigen. Serotyping data on recent Salmonella Typhimurium clinical isolates from the Democratic Republic of the Congo (DRC), however, indicate increasing levels of isolates without O:5. The importance and distribution of this loss of O:5 antigen in the population as well as the genetic mechanism responsible for the loss and chemical characteristics of the O-antigen are poorly understood. In this study, we Illumina whole-genome sequenced 354 Salmonella Typhimurium isolates from the DRC, which were isolated between 2002 and 2017. We used genomics and phylogenetics combined with chemical approaches (1H nuclear magnetic resonance [NMR], high-performance anion-exchange chromatography with pulsed amperometric detection [HPAEC-PAD], high-performance liquid chromatography-PAD [HPLC-PAD], and HPLC-size exclusion chromatography [HPLC-SEC]) to characterize the O-antigen features within the bacterial population. We observed convergent evolution toward the loss of the O:5 epitope predominantly caused by recombination events in a single gene, the O-acetyltransferase gene oafA. In addition, we observe further O-antigen variations, including O-acetylation of the rhamnose residue, different levels of glucosylation, and the absence of O-antigen repeating units. Large recombination events underlying O-antigen variation were resolved using long-read MinION sequencing. Our study suggests evolutionary pressure toward O-antigen variants in a region where invasive disease by Salmonella Typhimurium is highly endemic. This needs to be taken into account when developing O-antigen-based vaccines, as it might impact the breadth of coverage in such regions. IMPORTANCE The bacterium Salmonella Typhimurium forms a devastating burden in sub-Saharan Africa by causing invasive bloodstream infections. Additionally, Salmonella Typhimurium presents high levels of antimicrobial resistance, jeopardizing treatment. No licensed vaccine is available, but candidates are in development, with lipopolysaccharides being the principal target of protective immunity. The vaccines under development are designed based on the O:5 antigen variant of bacterial lipopolysaccharides. Data on recent Salmonella Typhimurium clinical isolates from the Democratic Republic of the Congo (DRC), however, indicate increasing levels of isolates without this O:5 antigen. We studied this loss of O:5 antigen in the population at the genetic and chemical levels. We genome sequenced 354 isolates from the DRC and used advanced bioinformatics and chemical methods to characterize the lipopolysaccharide features within the bacterial population. Our results suggest evolutionary pressure toward O-antigen variants. This needs to be taken into account when developing vaccines, as it might impact vaccine coverage.


Asunto(s)
Antiinfecciosos , Infecciones por Salmonella , Salmonella enterica , Sepsis , República Democrática del Congo/epidemiología , Humanos , Lipopolisacáridos , Antígenos O/genética , Infecciones por Salmonella/microbiología , Salmonella enterica/genética , Salmonella typhimurium , Serogrupo
12.
PLoS One ; 16(8): e0256883, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34464413

RESUMEN

BACKGROUND: The GeneXpert diagnostic platform from the US based company Cepheid is an automated molecular diagnostic device that performs sample preparation and pathogen detection within a single cartridge-based assay. GeneXpert devices can enable diagnosis at the district level without the need for fully equipped clinical laboratories, are simple to use, and offer rapid results. Due to these characteristics, the platform is now widely used in low- and middle-income countries for diagnosis of diseases such as TB and HIV. Assays for SARS-CoV-2 are also being rolled out. We aimed to quantify public sector investments in the development of the GeneXpert platform and Cepheid's suite of cartridge-based assays. METHODS: Public funding data were collected from the proprietor company's financial filings, grant databases, review of historical literature concerning key laboratories and researchers, and contacting key public sector entities involved in the technology's development. The value of research and development (R&D) tax credits was estimated based on financial filings. RESULTS: Total public investments in the development of the GeneXpert technology were estimated to be $252 million, including >$11 million in funding for work in public laboratories leading to the first commercial product, $56 million in grants from the National Institutes of Health, $73 million from other U.S. government departments, $67 million in R&D tax credits, $38 million in funding from non-profit and philanthropic organizations, and $9.6 million in small business 'springboard' grants. CONCLUSION: The public sector has invested over $250 million in the development of both the underlying technologies and the GeneXpert diagnostic platform and assays, and has made additional investments in rolling out the technology in countries with high burdens of TB. The key role played by the public sector in R&D and roll-out stands in contrast to the lack of public sector ability to secure affordable pricing and maintenance agreements.


Asunto(s)
Inversiones en Salud , Técnicas de Diagnóstico Molecular/economía , COVID-19/diagnóstico , COVID-19/virología , Bases de Datos Factuales , Infecciones por VIH/diagnóstico , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Técnicas de Diagnóstico Molecular/historia , SARS-CoV-2/aislamiento & purificación , Tuberculosis/diagnóstico , Estados Unidos
13.
PLoS One ; 16(10): e0258711, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34695154

RESUMEN

The Trypanosoma brucei repeat (TBR) is a tandem repeat sequence present on the Trypanozoon minichromosomes. Here, we report that the TBR sequence is not as homogenous as previously believed. BLAST analysis of the available T. brucei genomes reveals various TBR sequences of 177 bp and 176 bp in length, which can be sorted into two TBR groups based on a few key single nucleotide polymorphisms. Conventional and quantitative PCR with primers matched to consensus sequences that target either TBR group show substantial copy-number variations in the TBR repertoire within a collection of 77 Trypanozoon strains. We developed the qTBR, a novel PCR consisting of three primers and two probes, to simultaneously amplify target sequences from each of the two TBR groups into one single qPCR reaction. This dual probe setup offers increased analytical sensitivity for the molecular detection of all Trypanozoon taxa, in particular for T.b. gambiense and T. evansi, when compared to existing TBR PCRs. By combining the qTBR with 18S rDNA amplification as an internal standard, the relative copy-number of each TBR target sequence can be calculated and plotted, allowing for further classification of strains into TBR genotypes associated with East, West or Central Africa. Thus, the qTBR takes advantage of the single-nucleotide polymorphisms and copy number variations in the TBR sequences to enhance amplification and genotyping of all Trypanozoon strains, making it a promising tool for prevalence studies of African trypanosomiasis in both humans and animals.


Asunto(s)
Variaciones en el Número de Copia de ADN , ADN Protozoario/genética , Polimorfismo de Nucleótido Simple , Proteínas Protozoarias/genética , Secuencias Repetitivas de Ácidos Nucleicos , Trypanosoma brucei brucei/genética , Tripanosomiasis Africana/genética , ADN Protozoario/análisis , Trypanosoma brucei brucei/crecimiento & desarrollo , Tripanosomiasis Africana/parasitología
15.
J Clin Microbiol ; 48(9): 3325-30, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-20631112

RESUMEN

There is a need for standardization and simplification of the existing methods for molecular detection of Leishmania infantum in the canine reservoir host. The commercially available OligoC-TesT kit incorporates standardized PCR reagents with rapid oligochromatographic dipstick detection of PCR products and is highly sensitive for use in humans but not yet independently validated for use in dogs. Here we compare the sensitivity of OligoC-TesT with those of nested kinetoplast DNA (kDNA) PCR, nested internal transcribed spacer 1 (ITS-1) PCR, and a PCR-hybridization protocol, using longitudinal naturally infected canine bone marrow samples whose parasite burdens were measured by real-time quantitative PCR (qPCR). The sensitivity of OligoC-TesT for infected dogs was 70% (95% confidence interval [CI], 63 to 78%), similar to that of kDNA PCR (72%; 95% CI, 65 to 80%; P = 0.69) but significantly greater than those of PCR-hybridization (61%; 95% CI, 53 to 69%; P = 0.007) and ITS-1 nested PCR (54%; 95% CI, 45 to 62%; P < 0.001); real-time qPCR had the highest sensitivity (91%; 95% CI, 85 to 95%; P < 0.001). OligoC-TesT sensitivity was greater for polysymptomatic and oligosymptomatic dogs than for asymptomatic dogs (93%, 74%, and 61%, respectively; P = 0.005), a trend also observed for the other qualitative PCR methods tested (P

Asunto(s)
Enfermedades de los Perros/diagnóstico , Leishmaniasis/veterinaria , Parasitología/métodos , Reacción en Cadena de la Polimerasa/métodos , Animales , Médula Ósea/parasitología , Enfermedades de los Perros/parasitología , Perros , Leishmania infantum/genética , Leishmania infantum/aislamiento & purificación , Leishmaniasis/diagnóstico , Hibridación de Ácido Nucleico/métodos , Sensibilidad y Especificidad
16.
Trop Med Int Health ; 15(7): 806-10, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20487428

RESUMEN

OBJECTIVE: To estimate the sensitivity and specificity of the OligoC-TesT and nucleic acid sequence-based amplification coupled to oligochromatography (NASBA-OC) for molecular detection of Leishmania in blood from patients with confirmed visceral leishmaniasis (VL) and healthy endemic controls from Kenya. METHODS: Blood specimens of 84 patients with confirmed VL and 98 endemic healthy controls from Baringo district in Kenya were submitted to both assays. RESULTS: The Leishmania OligoC-TesT showed a sensitivity of 96.4% (95% confidence interval [CI]: 90-98.8%) and a specificity of 88.8% (95% CI: 81-93.6%), while the sensitivity and specificity of the NASBA-OC were 79.8% (95% CI: 67-87%) and 100% (95% CI: 96.3-100%), respectively. CONCLUSION: Our findings indicate high sensitivity of the Leishmania OligoC-TesT on blood while the NASBA-OC is a better marker for active disease.


Asunto(s)
Leishmania donovani/aislamiento & purificación , Leishmaniasis Visceral/diagnóstico , Reacción en Cadena de la Polimerasa/métodos , Replicación de Secuencia Autosostenida/métodos , Animales , ADN Protozoario/sangre , Enfermedades Endémicas , Humanos , Kenia/epidemiología , Leishmania donovani/genética , Leishmaniasis Visceral/epidemiología , ARN Protozoario/sangre , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
17.
Trop Med Int Health ; 15(7): 800-5, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20487429

RESUMEN

OBJECTIVE: To evaluate the repeatability and reproducibility of four simplified molecular assays for the diagnosis of Trypanosoma brucei spp. or Leishmania ssp. in a multicentre ring trial with seven participating laboratories. METHODS: The tests are based on PCR or NASBA amplification of the parasites nucleic acids followed by rapid read-out by oligochromatographic dipstick (PCR-OC and NASBA-OC). RESULTS: On purified nucleic acid specimens, the repeatability and reproducibility of the tests were Tryp-PRC-OC, 91.7% and 95.5%; Tryp-NASBA-OC, 95.8% and 100%; Leish-PCR-OC, 95.9% and 98.1%; Leish-NASBA-OC, 92.3% and 98.2%. On blood specimens spiked with parasites, the repeatability and reproducibility of the tests were Tryp-PRC-OC, 78.4% and 86.6%; Tryp-NASBA-OC, 81.5% and 89.0%; Leish-PCR-OC, 87.1% and 91.7%; Leish-NASBA-OC, 74.8% and 86.2%. CONCLUSION: As repeatability and reproducibility of the tests were satisfactory, further phase II and III evaluations in clinical and population specimens from disease endemic countries are justified.


Asunto(s)
Leishmania donovani/aislamiento & purificación , Leishmaniasis Visceral/diagnóstico , Reacción en Cadena de la Polimerasa/métodos , Replicación de Secuencia Autosostenida/métodos , Trypanosoma brucei gambiense/aislamiento & purificación , Tripanosomiasis Africana/diagnóstico , Animales , ADN Protozoario/análisis , Humanos , Leishmania donovani/genética , Reproducibilidad de los Resultados , Manejo de Especímenes/métodos , Trypanosoma brucei gambiense/genética
18.
PLoS Negl Trop Dis ; 14(7): e0008377, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32614856

RESUMEN

BACKGROUND: Non-typhoidal Salmonella (NTS) serotypes Typhimurium and Enteritidis are a major cause of bloodstream infections in children in sub-Saharan Africa but their reservoir is unknown. We compared pairs of NTS blood and stool isolates (with the same NTS serotype recovered in the same patient) for genetic similarity. METHODS: Between November 2013 and April 2017, hospital-admitted children (29 days to 14 years) with culture-confirmed NTS bloodstream infections were enrolled in a cross-sectional study at Kisantu Hospital, DR Congo. Stool cultures for Salmonella were performed on a subset of enrolled children, as well as on a control group of non-febrile hospital-admitted children. Pairs of blood and stool NTS isolates were assessed for genetic similarity by multiple-locus variable-number of tandem repeats (MLVA) and genomics analysis. RESULTS: A total of 299 children with NTS grown from blood cultures (Typhimurium 68.6%, Enteritidis 30.4%, other NTS 1.0%) had a stool sample processed; in 105 (35.1%) of them NTS was detected (Typhimurium 70.5%, Enteritidis 25.7%, other NTS 3.8%). A total of 87/105 (82.9%) pairs of blood and stool NTS isolates were observed (representing 29.1% of the 299 children). Among 1598 controls, the proportion of NTS stool excretion was 2.1% (p < 0.0001). MLVA types among paired isolates were identical in 82/87 (94.3%) pairs (27.4% of the 299 children; 61/66 (92.4%) in Typhimurium and 21/21 (100%) in Enteritidis pairs). Genomics analysis confirmed high genetic similarity within 41/43 (95.3%) pairs, showing a median SNP difference of 1 (range 0-77) and 1 (range 0-4) for Typhimurium and Enteritidis pairs respectively. Typhimurium and Enteritidis isolates belonged to sequence types ST313 lineage II and ST11 respectively. CONCLUSION: Nearly 30% of children with NTS bloodstream infection showed stool excretion of an NTS isolate with high genetic similarity, adding to the evidence of humans as a potential reservoir for NTS.


Asunto(s)
Bacteriemia/microbiología , Heces/microbiología , Salmonella/genética , Adolescente , Niño , Preescolar , Estudios Transversales , Humanos , Lactante , Polimorfismo de Nucleótido Simple , Salmonella/clasificación
19.
PLoS Negl Trop Dis ; 14(4): e0008121, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32240161

RESUMEN

BACKGROUND: Non-typhoidal Salmonella (NTS) are a major cause of bloodstream infection (BSI) in sub-Saharan Africa. This study aimed to assess its longitudinal evolution as cause of BSI, its serotype distribution and its antibiotic resistance pattern in Kisantu, DR Congo. METHODS: As part of a national surveillance network, blood cultures were sampled in patients with suspected BSI admitted to Kisantu referral hospital from 2015-2017. Blood cultures were worked-up according to international standards. Results were compared to similar data from 2007 onwards. RESULTS: In 2015-2017, NTS (n = 896) represented the primary cause of BSI. NTS were isolated from 7.6% of 11,764 suspected and 65.4% of 1371 confirmed BSI. In children <5 years, NTS accounted for 9.6% of suspected BSI. These data were in line with data from previous surveillance periods, except for the proportion of confirmed BSI, which was lower in previous surveillance periods. Salmonella Typhimurium accounted for 63.1% of NTS BSI and Salmonella Enteritidis for 36.4%. Of all Salmonella Typhimurium, 36.9% did not express the O5-antigen (i.e. variant Copenhagen). O5-negative Salmonella Typhimurium were rare before 2013, but increased gradually from then onwards. Multidrug resistance was observed in 87.4% of 864 NTS isolates, decreased ciprofloxacin susceptibility in 7.3%, ceftriaxone resistance in 15.7% and azithromycin resistance in 14.9%. A total of 14.2% of NTS isolates, that were all Salmonella Typhimurium, were multidrug resistant and ceftriaxone and azithromycin co-resistant. These Salmonella isolates were called extensively drug resistant. Compared to previous surveillance periods, proportions of NTS isolates with resistance to ceftriaxone and azithromycin and decreased ciprofloxacin susceptibility increased. CONCLUSION: As in previous surveillance periods, NTS ranked first as the cause of BSI in children. The emergence of O5-negative Salmonella Typhimurium needs to be considered in the light of vaccine development. The high proportions of antibiotic resistance are worrisome.


Asunto(s)
Antibacterianos/farmacología , Bacteriemia/epidemiología , Bacteriemia/microbiología , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Infecciones por Salmonella/epidemiología , Infecciones por Salmonella/microbiología , Salmonella typhimurium/efectos de los fármacos , Salmonella typhimurium/aislamiento & purificación , Adolescente , Adulto , Azitromicina , Ceftriaxona , Niño , Preescolar , Ciprofloxacina , Congo/epidemiología , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Pruebas de Sensibilidad Microbiana , Salmonella/efectos de los fármacos , Infecciones por Salmonella/diagnóstico , Salmonella enteritidis/efectos de los fármacos , Serogrupo , Fiebre Tifoidea/tratamiento farmacológico , Adulto Joven
20.
Cell Rep ; 30(11): 3821-3836.e13, 2020 03 17.
Artículo en Inglés | MEDLINE | ID: mdl-32187552

RESUMEN

The C-terminal variants G1 and G2 of apolipoprotein L1 (APOL1) confer human resistance to the sleeping sickness parasite Trypanosoma rhodesiense, but they also increase the risk of kidney disease. APOL1 and APOL3 are death-promoting proteins that are partially associated with the endoplasmic reticulum and Golgi membranes. We report that in podocytes, either APOL1 C-terminal helix truncation (APOL1Δ) or APOL3 deletion (APOL3KO) induces similar actomyosin reorganization linked to the inhibition of phosphatidylinositol-4-phosphate [PI(4)P] synthesis by the Golgi PI(4)-kinase IIIB (PI4KB). Both APOL1 and APOL3 can form K+ channels, but only APOL3 exhibits Ca2+-dependent binding of high affinity to neuronal calcium sensor-1 (NCS-1), promoting NCS-1-PI4KB interaction and stimulating PI4KB activity. Alteration of the APOL1 C-terminal helix triggers APOL1 unfolding and increased binding to APOL3, affecting APOL3-NCS-1 interaction. Since the podocytes of G1 and G2 patients exhibit an APOL1Δ or APOL3KO-like phenotype, APOL1 C-terminal variants may induce kidney disease by preventing APOL3 from activating PI4KB, with consecutive actomyosin reorganization of podocytes.


Asunto(s)
Actomiosina/metabolismo , Apolipoproteína L1/química , Apolipoproteína L1/genética , Apolipoproteínas L/metabolismo , Enfermedades Renales/metabolismo , Mutación/genética , Secuencia de Aminoácidos , Apolipoproteína L1/orina , Calcio/metabolismo , Línea Celular , Retículo Endoplásmico/efectos de los fármacos , Retículo Endoplásmico/metabolismo , Retículo Endoplásmico/ultraestructura , Aparato de Golgi/efectos de los fármacos , Aparato de Golgi/metabolismo , Aparato de Golgi/ultraestructura , Humanos , Enfermedades Renales/orina , Glomérulos Renales/metabolismo , Glomérulos Renales/patología , Antígenos de Histocompatibilidad Menor/metabolismo , Proteínas Sensoras del Calcio Neuronal/metabolismo , Neuropéptidos/metabolismo , Fenotipo , Fosfatos de Fosfatidilinositol/metabolismo , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Podocitos/efectos de los fármacos , Podocitos/metabolismo , Podocitos/ultraestructura , Poli I-C/farmacología , Canales de Potasio/metabolismo , Unión Proteica/efectos de los fármacos , Estructura Secundaria de Proteína
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