ABSTRACT
Resumen La Tuberculosis (TB) es una de las diez causas principales de muerte en el mundo, y la principal causa por un solo agente infeccioso. La detección precoz del Complejo Mycobacterium tuberculosis (CMT) y de mutaciones que confieren resistencia a los principales fármacos empleados en la terapia antituberculosa, contribuye a la disminución de la transmisión de la infección y consecuentemente a la expansión de la TB resistente. La prueba GeneXpertMTB/RIF, mediante ensayos de PCR en tiempo real identifica de manera simultánea el CMT y detecta las mutaciones más frecuentemente asociadas con resistencia a rifampicina. El objetivo de este estudio es comparar el rendimiento del método GeneXpertMTB/RIF en lavado broncoalveolar (BAL) frente al lavado bronquial (LB) en pacientes inmunocompetentes con sospecha clínica de TB pulmonar, sin documentación microbiológica previa. Materiales y Métodos: Se incorporaron prospectivamente pacientes con infiltrados radiológicos pulmonares compatibles con TB activa o residual sin tratamiento previo, con baciloscopia directa negativa o tos improductiva, para valoración de enfermedad activa. Se identificó el segmento más afectado mediante tomografía axial computada realizándose broncoscopia con BAL en dicho segmento, seguido de LB en todo el lóbulo afectado. Se consideró significativa una recuperación del BAL >40%. Las muestras obtenidas fueron procesadas para baciloscopia, cultivo y GeneXpertMTB/RIF. Se analizó la sensibilidad (S), especificidad (E), valor predictivo positivo (VPP) y valor predictivo negativo (VPN) tomando como referencia el cultivo en medio sólido para el diagnóstico del CMT. Resultados: Se incorporaron 20 pacientes, se excluyeron 3 por no obtener una muestra representativa de BAL. Se estudiaron 17 pacientes (11 mujeres, 65%), edad 37.2 ± 16.3 años. Se identificó al CMT con métodos convencionales en 10 pacientes: 10 con cultivo positivo en LB y 9 en BAL. Comparando con métodos convencionales, 6 de 17 muestras obtenidas mediante BAL fueron positivas con GeneXpertMTB/RIF: S = 60.0% (IC 31%-83%), E = 100% (IC 65%-100%), VPP = 100% (IC 61%-100%) y VPN = 64% (IC 35.4%-84.8%). Con LB, 9 de 17 fueron Xpert MTB/RIF positivas: S = 90.0% (IC 60%-98%), E = 100% (IC 65%-100%), VPP = 100% (IC 70%-100%) y VPN = 88% (IC 53%-98%). Todos los casos identificados con GeneXpertMTB/RIF fueron verdaderos positivos en relación con los cultivos convencionales. Conclusión: Considerando al cultivo sólido como método de referencia, el LB resultó más sensible que el BAL para el diagnóstico de infección tuberculosa por el método de GeneXpertMTB/RIF en los pacientes con sospecha de TB sin documentación microbiológica previa.
Subject(s)
Tuberculosis , Communicable Diseases , Bronchoalveolar LavageABSTRACT
Abstract Tuberculosis (TB) is one of the ten leading causes of death worldwide, and the main cause from a single infectious agent. Early detection of the Mycobacterium tuberculosis complex (MTC) and of mutations conferring resistance to the main drugs used in antituberculous treatment contributes to reducing the transmission of the infection, and consequently the spread of resistant TB. The GeneXpert MTB/ RIF test identifies the MTC and simultaneously detects mutations most frequently associated with rifampicin resistance, through real-time PCR testing. The purpose of this study was to compare the performance of the GeneXpert MTB/RIF method in bronchoalveolar lavage (BAL) with bronchial lavage (LB) in immunocompetent patients with clinical suspicion of pulmonary TB without any previous microbiological documentation. Materials and Methods: We prospectively enrolled patients with radiologic pulmonary infiltrates compatible with active or residual TB without previous treatment, with negative direct bacilloscopy or nonproductive cough, for the assessment of active disease. We identified the most affected segment through computed axial tomography and bronchoscopy with BAL in said segment, followed by BL of the affected lobe. A BAL recovery > 40% was considered significant. The samples obtained were processed for bacilloscopy, culture and GeneXpert MTB/RIF. We analyzed sensitivity (S), specificity (SP), positive predictive value (PPV) and negative predictive value (NPV), taking the solid culture medium as reference for the diagnosis of MTC. Results: We included 20 patients; 3 were excluded because they didn't have a representative BAL sample. 17 patients were evaluated (11 women, 65%), age 37.2 ± 16.3. The MTC was identified through conventional methods in 10 patients: 10 with positive culture in BL and 9 in BAL. In comparison with the conventional methods, 6 out of 17 samples obtained through BAL had a positive result for GeneXpert MTB/ RIF: S = 60.0% (CI 31%-83%), SP = 100% (CI 65%-100%), PPV = 100% (CI 61%-100%) and NPV = 64% (CI 35.4%-84.8%). With BL, 9 out of 17 had a positive result for Xpert MTB/RIF: S = 90.0% (CI 60%-98%), SP = 100% (CI 65%-100%), PPV = 100% (CI 70%-100%) and NPV = 88% (CI 53%-98%). All the cases identified with GeneXpert MTB/RIF were true positives in relation to conventional cultures. Conclusion: Considering the solid culture as reference method, the BL was more sensitive than the BAL for the diagnosis of tubercu lous infection through the GeneXpert MTB/RIF method in patients with suspected TB without previous microbiological documentation.
Subject(s)
Tuberculosis , Communicable Diseases , Bronchoalveolar LavageABSTRACT
Resumen Las rickettsiosis son enfermedades zoonóticas transmitidas por artrópodos vectores, que en Argentina presentan 2 escenarios epidemiológicos diferenciados. Uno, en las yungas de Salta y Jujuy, involucra vectores pertenecientes al «complejo Amblyomma cajennense¼ (A. sculptum y A. toneliae) y a Rickettsia rickettsii como agente etiológico. En este escenario la forma clínica de la enfermedad se conoce como fiebre manchada (FM) y se presenta con manifestaciones cutáneas y sistémicas graves. El otro escenario incluye 2 zonas: una la del Delta del Río Paraná y Bahía de Samborombón, donde Amblyomma triste actúa como vector; otra, las provincias de Córdoba, La Rioja, San Luis y La Pampa, donde el vector es Amblyomma tigrinum. En este segundo escenario Rickettsia parkeri es el agente causal, y la FM se manifiesta con un cuadro benigno y autolimitado. En este trabajo describimos un caso fatal de FM por R. rickettsii en El Tunal, Salta, y el primer caso de FM por R. parkeri en San Juan.
Abstract Rickettsioses are zoonotic tick-borne diseases. In Argentina, there are two epidemiological scenarios: jungle of Salta and Jujuy, involving vectors from the "Amblyomma cajennense Complex" (A. sculptum, and A. toneliae) and Rickettsia rickettsii as the main etiological agent; and the second scene to Delta del Rio Paraná and Samborombón Bay, where Amblyomma triste acts as a vector; and the provinces of Córdoba, La Rioja, San Luis and La Pampa where Amblyomma tigrinum is the vector. In this second scenario, Rickettsia parkeri is the causal agent. The spotted fever (SF) due to R. rickettsii is responsible for a severe cutaneous and systemic disease. Contrarily, R. parkeri produces benign and self-limited clinical manifestation. Here we describe a fatal SF case by R. rickettsii, in El Tunal, Salta and the first SF case due to R. parkeri in San Juan.
Subject(s)
Humans , Female , Middle Aged , Rickettsia rickettsii/pathogenicity , Rickettsia Infections/diagnosis , Tick-Borne Diseases/therapy , Skin Manifestations , Zoonoses/epidemiologyABSTRACT
Rickettsioses are zoonotic tick-borne diseases. In Argentina, there are two epidemiological scenarios: jungle of Salta and Jujuy, involving vectors from the "Amblyomma cajennense Complex" (A. sculptum, and A. toneliae) and Rickettsia rickettsii as the main etiological agent; and the second scene to Delta del Rio Paraná and Samborombón Bay, where Amblyomma triste acts as a vector; and the provinces of Córdoba, La Rioja, San Luis and La Pampa where Amblyomma tigrinum is the vector. In this second scenario, Rickettsia parkeri is the causal agent. The spotted fever (SF) due to R. rickettsii is responsible for a severe cutaneous and systemic disease. Contrarily, R. parkeri produces benign and self-limited clinical manifestation. Here we describe a fatal SF case by R. rickettsii, in El Tunal, Salta and the first SF case due to R. parkeri in San Juan.
Subject(s)
Spotted Fever Group Rickettsiosis/diagnosis , Argentina , Fatal Outcome , Female , Humans , Middle AgedABSTRACT
Helicobacter pylori colonizes the human gastric mucosa, leading to a spectrum of gastric diseases in susceptible populations. Here we announce the draft genome sequences of strains HPARG8G and HPARG63. The data for both genome sequences provide insights regarding the diversity in gene content and rearrangement of the genomic islands commonly harbored by H. pylori.
ABSTRACT
Genetic diversification allows Helicobacter pylori to persist during chronic colonization/infection. We investigated the intra-host variation of several markers that suggested microevolution in patients with chonic gastritis (CG) and peptic ulcer disease (PUD). One-hundred twenty-six isolates recovered from 14 patients with CG and 13 patients with PUD were analysed. cag pathogenicity island (cagPAI), oipA, vacA, bab gene status and the presence of jhp0926, jhp0945, jhp0947, jhp0949 and jhp0940 genes from the genomic Plasticity Zone (PZ) were taken into accout to investigate intra-host variation. lspA-glmM-RFLP was performed to identify mixed infections. Only one patient was colonised/infected by two ancestrally unrelated strains. Among the 126 isolates, a significant association among cagPAI genotypes, oipA status and vacA alleles was indicated. Complete cagPAI, oipA "on", and vacA s1-m1 variants were significantly found in patients with PUD, without intra-host variations. Isolates from 7/14 patients with CG lacked babA in all chromosomal loci. In contrast, isolates from all or several biopsies of PUD patients carried babA, but in one patient only, the isolates showed positive Lewis b (Leb) binding assay. Considering cagPAI, vacA, oipA, bab genotypes, intra-host variation was also significantly higher in patients with CG. Conversely, a similarly high intra-host variation in almost PZ genes was observed in isolates from patients with CG and PUD. In conclusion, the lowest intra-host variation in cagPAI, oipA, vacA, and bab genes found in patients with PUD suggests the selection of a particular variant along the bacteria-host environment interplay during ulceration development. However, the predominance of this variant may be a refletion of the multifactorial etiology of the disease rather than the cause, as it was also found in patients with CG. The intra-host variation in PZ genes may predict that this genomic region and the other markers of microevolution studied evolve under diverse pressure(s).
Subject(s)
Gastritis/microbiology , Helicobacter Infections/microbiology , Helicobacter pylori/genetics , Peptic Ulcer/microbiology , Bacterial Proteins/genetics , Chi-Square Distribution , DNA, Bacterial/genetics , Evolution, Molecular , Genes, Bacterial , Genetic Markers/genetics , Genetic Variation , Helicobacter pylori/classification , Helicobacter pylori/isolation & purification , HumansABSTRACT
Helicobacter pylori putative virulence factors can undergo a continuously evolving mechanism as an approach to bacterial adaptation to the host changing environment during chronic infection. oipA, vacA and dupA genetic diversity among isolates from multiple biopsies (niches) from the antrum and corpus of 40 patients was investigated. A set of 229 isolates was examined. Direct DNA sequence analysis of amplified fragments was used to study oipA 'on/off' expression status as well as the presence of C or T insertion in jhp0917 that originates a continuous (jhp0917-jhp0918) dupA gene. vacA alleles were identified by multiplex PCR. Different inter-niches oipA CT repeat patterns were observed in nine patients; in six of these, 'on' and 'off' mixed patterns were found. In three of these nine patients, different vacA alleles were also observed in a single host. Inter-niche dupA differences involved the absence and presence of jhp0917 and/or jhp0918 or mutations in dupA, including those that may originate a non-functional gene, and they were also present in two patients with mixed oipA CT patterns and in another seven patients. Evidence of mixed infection was observed in two patients only. In conclusion, oipA and dupA genes showed similar inter-niche variability, occurring in approximately 1/4 patients. Conversely, vacA allele microevolution seemed to be a less common event, occurring in approximately 1/10 patients, probably due to the mechanism that this gene evolves 'in vivo'.
