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Resumen La enfermedad del legionario (EL) es una neumonía aguda grave, que ocurre espo-rádicamente o como epidemias, y que, generalmente, requiere hospitalización. El objetivo deeste trabajo fue describir la experiencia en el abordaje diagnóstico de laboratorio de la ELen Argentina durante el período 2016-2021. Se analizaron 168 especímenes clínicos correspondientes a 93 casos de neumonía con sospecha de EL. Las pruebas de laboratorio incluyeron ladeterminación del antígeno soluble de Legionella pneumophila serogrupo 1 en orina, la detec-ción de ADN de Legionella spp. en secreciones respiratorias bajas, por métodos moleculares convencionales y comerciales de tipo sindrómico, y el cultivo en medio selectivo. Se confirmó EL en 12 pacientes. El antígeno urinario confirmó el diagnóstico de 8 de ellos. Se recuperó L. pneumophila mediante el cultivo del material respiratorio de 6 pacientes que correspondieron a casos de neumonía asociada a cuidados de la salud y que fueron previamente diagnosticados por el método molecular comercial. La mitad de ellos no presentó antigenuria detectable. En un único paciente no hubo antigenuria detectable ni recuperación de Legionella en cultivo, y la confirmación de EL se basó en la detección de ADN de Legionella spp. por PCR en secreción respiratoria y el vínculo epidemiológico con otro caso de EL confirmado por cultivo. La detección del antígeno urinario es la prueba diagnóstica de primera línea. Sin embargo, la incorporación de métodos moleculares complementarios ha demostrado evitar falsos negativos y contribuir a un mejor conocimiento de la verdadera incidencia de la enfermedad.
Abstract Legionnaires' disease (LD) is severe acute pneumonia that occurs in sporadic or epidemic form, and generally requires hospitalizaron. The objective of this work was to describe the experience in the LD laboratory diagnostic approach in Argentina during the period 2016-2021. The laboratory analyzed 168 clinical specimens from 93 cases of suspected LD pneu-monia. Laboratory tests included the detection of the soluble antigen of Legionella pneumophila serogroup 1 in urine sample, detection of DNA of Legionella spp. in lower respiratory secre-tions by conventional and commercial molecular methods and isolation in selective medium. LD was confirmed in 12 patients. The urinary antigen allowed the diagnosis for 8 patients. L. pneumophila was isolated from the respiratory material of 6 patients suffering from health care-associated pneumonia, who had been previously diagnosed using the commercial molecular method. Fifty percent of these cases did not show detectable urinary antigen. A single patient did not shows neither detectable antigenuria nor isolation of Legionella from the respiratory sample and was diagnosed as a confirmed case of LD by the detection of DNA of Legionella spp. by PCR directly from the respiratory secretion and the epidemiological link with another case of confirmed LD by culture. Urinary antigen detection is the first-line diagnostic test. However, the incorporation of complementary molecular methods has proved to avoid false negatives and contributed to a better understanding of the true incidence of the disease.
RESUMEN
Aims: Globally, viral agents, especially herpes simplex virus (HSV), have overtaken the bacterial causes of genital ulcers. Very few laboratories in India, perform culture techniques and polymerase chain reaction (PCR) for diagnosis of genital ulcers. This study aimed to establish the utility of existing tests, which are cheaper and need less technical expertise, when compared to newer tests such as PCR.Study Design: This cross sectional study was carried out to determine the aetiology of genital ulcers, with emphasis on diagnosis of herpetic ulcers, using newer and more accurate methods of diagnosis and evaluating their performance by comparing against viral culture as gold standard test.Place and Duration of the Study: The study was carried out over a period of one year in the Apex Regional Sexually Transmitted Diseases (STD) Centre at Safdarjung Hospital, New Delhi and the Department of Microbiology, AIIMS, New Delhi.Methodology: Fifty three patients with genital ulcers were included in the study. Specimens from ulcers were taken for various tests, including Giemsa stain, ELISA for HSV-1 & 2, PCR and Viral culture for HSV.Results: HSV was identified in 31 of 53 cases (58.5%), including 03 cases of HSV-1, and 28 cases of HSV-2. Sensitivity and specificity of PCR was 90.0% and 84.85%, respectively. Viral culture positivity was 37.7%.Conclusion: Genital herpes is associated with an increased risk of Human Immunodeficiency Virus (HIV) acquisition, and clinical manifestations are diverse; hence a presumptive diagnosis should be confirmed by reliable laboratory tests. Nucleic acid amplification tests (NAAT) are the most sensitive methods for direct detection of HSV. The extensive validation of these tests allows for their application in routine laboratory settings with consistency and greater diagnostic accuracy. When standardised and used, PCR is a highly reproducible, rapid and labour efficient method for HSV detection.