Marcela agos L

Diagnóstico de la infección por Treponema pallidum en pacientes con sífilis temprana y neurosífilis mediante reacción de la polimerasa en cadena

Syphilis is a sexually transmitted disease caused by Treponema pallidum. The diagnosis is based mainly in clinical presentation and non-specific assays. PCR-based diagnosis has been suggested as an attractive alternative method. The aim of this study was the validation of a PCR-based test for the diagnosis of early syphilis (ES) and neurosyphilis (NS). Clinical samples of mucocutaneous lesions and cerebrospinal fluid (CSF) specimens from patients previously diagnosed for ES and NS respectively using an enlarged gold standard, were tested by PCR. The reaction was done using primers targeting the tpN47 gene. Twenty out of 21 mucocutaneous samples from patients diagnosed with ES were positive by PCR, with a clinical sensitivity of 95%. Four out of 8 CSF samples from patients previously diagnosed with NS were positive by PCR, with a clinical sensitivity of 50%. The clinical specificity for both ES and NS was 100%. The PCR sensitivity and specificity for mucocutaneous samples allowed us to implement this assay in our laboratory for routine diagnosis. Although the sensitivity of the PCR in CSF was low, it may be useful to support clinical diagnosis.

Aviso de valores de alerta por parte del laboratorio clínico en una red de salud universitaria

Background: An alert value is a result suggesting that the patient is at imminent danger unless appropriate remedial actions begin promptly. Report of alert values (AV) by the clinical laboratories has taken special relevance in recent years due to its contribution to patients care. Aim: To report results of AV informed during 2007 within the Health Network of the Pontificia Universidad Catolica de Chile. Material and methods: Analysis of AV recorded in a centralized database of the laboratories of the health network, between January and December, 2007. Results: Total number of AV was 5.366, which represented 0.3% of total examinations and corresponded mainly to the clinical chemistry area. Potassium levels generated the higher number of AV detected, followed by positive blood cultures. Eighty two percent of AV corresponded to hospitalized patients. The greater number of AV was reported to intermediate and intensive care services. Thirty two percent of AV was informed to the physician or professional in charge of the patient within 5 minutes of obtaining the results and 79% within 30 minutes. Conclusions: To obtain a real impact on patient management, it is fundamental to shorten the iapse between the obtainment of tests results and the warning, supported on appropriate computerized systems, and to spread the procedure to all personnel involved in patients care (RevMed Chile 2009; 137: 1137-44).

Micetoma por Actinomadura madurae en el pie. Reporte de un caso en Chile

Mycetoma is a chronic infection that affects skin, subcutaneous tissue and bone. Its etiology can be mycotic or bacterial. It affects mainly the lower extremities of middle age men living in tropical climates. We report a 44-year-old male living in a template zone, consulting for swelling and pain in the left foot, lasting for 10 years. Physical examination showed a swollen left foot with hyperpigmented skin and a few crusted papules. Radiology showed an extensive bone involvement of the midfoot with several oval and radiolucid images. Magnetic resonance showed soft and bone tissue involvement, with multiple oval and low intensity images in T1 and T2. The biopsy was compatible with an unspecific chronic osteomyelitis. A bacterial identiFcation by polymerase chain reaction and sequencing in the biopsy determined the presence of an Actinomadumra madurae. Treatment with cotrimaxazol was started.

PCR universal o de amplio espectro: Un aporte a la detección e identificación de bacterias y hongos en la práctica clínica

The use of techniques for the detection of nucleic acids such as thepolymerase chain reaction (PCR) has had a major impact on microbiological analysis, playing animportant role in the clinical laboratory. Most of the techniques currently used are designed forspecific detection of a particular microorganism. However, infectious agents can also be identifiedeven if genus or species are unknown, using universal primers to amplify bacterial or fungal DNAand then identify the species by sequency (universal or wide spectrum PCR). This methodology isapplied in cultures that are difficult to identify using phenotypic techniques, and more recently it isalso being used directly in clinical samples, where the detection and identification of the infectiousagent by traditional techniques is difficult or not possible (Rev Med Chile 2009; 137: 1122-5).(

Diabetes Mellitus por mutación en el gen de Glucokinasa. Caso Clínico

Maturity-Onset Diabetes of the Young (MODY) refers to a heterogeneous group of monogenic diabetes. Unlike other types of MODY characterized by genetic defects in transcription factors, MODY 2 is triggered by metabolic alterations caused by mutations of glucokinase (GCK), the first enzyme of the glycolytic pathway. We report a three-generation Chilean family with multiple cases affected with this disease. The index case is a patient who presented severe neonatal hyperglycemia (831 mg/dl, without ketosis) requiring continuous infusion of insulin, which was suspended after 48 hours with normalization of blood glucose. Subsequently, continuous glucose monitoring at 4 months of age revealed 47% of tissue glucose levels above 140 mg/dl, with fasting glucose levels between 120 and 166 mg/dl. The genetic analysis revealed a previously reported mutation in heterozygous state of the GCK gene (c.148C>T; p.His50Tyr). This mutation was also identified in more than one affected relative in the last two generations, with a transmission pattern suggestive of dominant inheritance. GCK gene sequencing led to a correct molecular diagnosis of MODY 2 while bioinformatic analysis indicated the possible molecular causes of the enzyme dysfunction. The knowledge of the molecular diagnosis allowed an adequate medical treatment for this disease.

Conceptos básicos sobre el estudio de paternidad

Nowadays, the analysis of genetic markers is a very important and validated tool for the identification of individuals, and for paternity testing. To do so, highly variable regions of the human genome are analyzed, making it possible to obtain the genetic profile of an individual, and to distinguish between different individuals. The methodology used is basically the same all over the world, consisting in the analysis of 13 to 15 markers. To assign biological paternity the child must have inherited the characteristics from the alleged father in each of the genetic markers analyzed. This analysis achieves a certainty higher than with any other test, which is expressed as the probability of paternity. This probability has to be at least 99.9%, but greater probabilities are usually obtained, especially if the mother is included in the analysis. If the characteristics of two or more genetic markers from the alleged father are absent in the child, biological paternity is excluded.

Tests genéticos: Definición, métodos, validación y utilidad clínica

El conocimiento del genoma humano ha dado lugar a un aumento explosivo de los test geneticos disponibles para uso clinico. Las metodologias utilizadas en este tipo de tests son muy variadas, permitiendo desde el estudio de los cromosomas hasta el analisis de una base nucleotidica. Previo a su utilizacion en el ambito clinico, estos tests deben tener una evaluacion que incluya su validacion analitica y clinica y determinacion de la utilidad clinica, ademas de cumplir, como cualquier otro examen, con requisitos para el aseguramiento de la calidad. Recientemente, el CDC (Centersfor Disease Control and Prevention, EE. UU) hapublicado recomendaciones para las buenas practicas de laboratorio de tests moleculares que se utilizan para el diagnostico de enfermedades geneticas, que abarcan la fase pre- analitica, analitica y post-analitica. Dentro de estas destacan: la importancia de la seleccion adecuada de los tests, la disponibilidad de la informacion sobre el desempeno de las tecnicas utilizadas, las practicas de control de calidad, la capacitacion del personal involucrado y la elaboracion de un informe de resultados que permita al clinico interpretarlos adecuadamente, incluyendo sensibilidad y especificidad. Tomando en cuenta que los recientes avances en genetica han modificado y seguiran modificando la practica clinica, los test geneticos deben cumplir con las exigencias de calidady seguridad que permitan su uso optimo.