[Legionnaires' disease in Argentina: Evolution of the laboratory diagnostic strategy]. / Enfermedad del legionario en Argentina: evolución de la estrategia diagnóstica en el laboratorio.

Legionnaires' disease (LD) is severe acute pneumonia that occurs in sporadic or epidemic form, and generally requires hospitalization. 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 pneumonia. 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 secretions 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.

[Autochthonous Rickettsia parkeri rickettsiosis in the Paranaense Forest, Misiones, Argentina]. / Caso autóctono de rickettsiosis por Rickettsia parkeri en la Selva Paranaense, Misiones, Argentina.

We report an autochthonous case of Rickettsia parkeri rickettsiosis occurred in June 2018 in a forested area of the Urugua-í Provincial Park, Misiones, Argentina. No previous records of this disease in humans have been previously reported in this region. The epidemiological, ecological, clinical, and laboratory features required for a proper diagnosis and adequate treatment are described here. The fact of considering rickettsiosis as a differential diagnosis in a patient with exanthematic acute febrile syndrome is highlighted, being the epidemiological history of exposure to the vector (ticks of the genus Amblyomma) an essential element.

SARS-CoV-2 and Chlamydia pneumoniae co-infection: A review of the literature.

Bacterial co-pathogens are commonly identified in viral respiratory infections and are important causes of morbid-mortality. The prevalence of Chlamydia (C.) pneumoniae infection in patients infected with SARS-CoV-2 has not been sufficiently studied. The objective of the present review was to describe the prevalence of C. pneumoniae in patients with coronavirus disease 2019 (COVID-19). A search in MEDLINE and Google Scholar databases for English language literature published between January 2020 and August 2021 was performed. Studies evaluating patients with confirmed COVID-19 and reporting the simultaneous detection of C. pneumoniae were included. Eleven articles were included in the systematic review (5 case cross-sectional studies and 6 retrospective studies). A total of 18450 patients were included in the eleven studies. The detection of laboratory-confirmed C. pneumoniae infection varied between 1.78 and 71.4% of the total number of co-infections. The median age of patients ranged from 35 to 71 years old and 65% were male. Most of the studies reported one or more pre-existing comorbidities and the majority of the patients presented with fever, cough and dyspnea. Lymphopenia and eosinopenia were described in COVID-19 co-infected patients. The main chest CT scan showed a ground glass density shadow, consolidation and bilateral pneumonia. Most patients received empirical antibiotics. Bacterial co-infection was not associated with increased ICU admission and mortality. Despite frequent prescription of broad-spectrum empirical antimicrobials in patients with coronavirus 2-associated respiratory infections, there is a paucity of data to support the association with respiratory bacterial co-infection. Prospective evidence generation to support the development of an antimicrobial policy and appropriate stewardship interventions specific for the COVID-19 pandemic are urgently required.

[Spotted fever in Argentina. Description of two clinical cases]. / Fiebre manchada en Argentina. Descripción de dos casos clínicos.

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.

[Helicobacter cinaedi bacteremia: Presentation of the first cases reported in Argentina]. / Bacteriemia por Helicobacter cinaedi: presentación de los primeros casos descritos en Argentina.

Two cases of bacteremia caused by Helicobacter cinaedi are presented. The first case was diagnosed in a 76-year-old male patient, and was secondary to a vascular access device placement; the second case corresponded to a febrile infant of 37 days of life, and was associated with acute gastroenteritis. H. cinaedi is a microorganism difficult to grow in different culture media and also to identify to species level. In both cases, the microscopic observation of blood culture bottles, the use of mass spectrometry and the subsequent sequencing of the hsp60 gene were essential. In the recent literature, H. cinaedi infections are being reported more frequently. In this report we present the first documented cases of bacteremia caused by H. cinaedi in Argentina.

[Development and evaluation of an in-house database for quick identification of Burkholderia contaminans by MALDI-TOF MS]. / Desarrollo y evaluación de una base de datos in house para la identificación rápida de Burkholderia contaminans por EM MALDI-TOF.

MALDI-TOF (matrix assisted laser desorption ionization-time of flight) mass spectrometry (MS) proved to be a robust tool for the identification of numerous taxonomic groups. However, it has limitations. A key advantage of this technique is the flexibility for the incorporation of protein profiles of microorganisms not included in the commercial database. Due to the prevalence of Burkholderia contaminans in fibrocystic patients in Argentina and the fact that rapid and reliable microbiological diagnosis is crucial in them, MALDI-TOF MS emerges as a strategic tool. The aim of this work was to develop an additional database with peptide spectra of reference isolates of B. contaminans. This database demonstrated to be successful for the identification of 97% of the isolates analyzed. Therefore, MALDI-TOF MS with the extended database was a useful tool for the identification and differentiation of other related species to B. contaminans.

[Bartonella henselae: Serological evidence in pediatric patients with clinical suspicion of cat scratch disease]. / Bartonella henselae: evidencia serológica en pacientes pediátricos con sospecha clínica de enfermedad por arañazo de gato.

Cat scratch disease (CSD) is caused by Bartonella henselae, which mainly affects children. The cat is the reservoir. The laboratory diagnosis is based on the detection of antibodies by the Indirect Immunofluorescence (IFI) assay. The objective of this study was to analyze the serological evidence of B. henselae infection in pediatric patients that met the clinical/epidemiological criteria for suspected CSD. We studied 92 patients, who were categorized into four serological groups: 1) IgG (+)/IgM(+), 31,5% (n=29); 2) IgG (-)/IgM(+), 10,9% (n=10); 3) IgG (+)/IgM(-), 9,8% (n=9); 4) IgG (-)/IgM(-), 47,8% (n=44). These findings aim to promote future works for investigating the seroprevalence of Bartonella spp. in Argentina, which will allow us to know the importance of this zoonosis in our population and to evaluate new cut-off points of the technique.

Circulating Monocyte-Like Myeloid Derived Suppressor Cells and CD16 Positive Monocytes Correlate With Immunological Responsiveness of Tuberculosis Patients.

Alterations of myeloid cell populations have been reported in patients with tuberculosis (TB). In this work, we studied the relationship between myeloid-derived suppressor cells (MDSC) and monocytes subsets with the immunological responsiveness of TB patients. Individuals with active TB were classified as low responders (LR-TB) or high responders (HR-TB) according to their T cell responses against a cell lysate of Mycobacterium tuberculosis (Mtb-Ag). Thus, LR-TB, individuals with severe disease, display a weaker immune response to Mtb compare to HR-TB, subjects with strong immunity against the bacteria. We observed that LR-TB presented higher percentages of CD16 positive monocytes as compared to HR-TB and healthy donors. Moreover, monocyte-like (M-MDSC) and polymorphonuclear-like (PMN-MDSC) MDSC were increased in patients and the proportion of M-MDSC inversely correlated with IFN-γ levels released after Mtb-Ag stimulation in HR-TB. We also found that LR-TB displayed the highest percentages of circulating M-MDSC. These results demonstrate that CD16 positive monocytes and M-MDSC frequencies could be used as another immunological classification parameter. Interestingly, in LR-TB, frequencies of CD16 positive monocytes and M-MDSC were restored after only three weeks of anti-TB treatment. Together, our findings show a link between the immunological status of TB patients and the levels of different circulating myeloid cell populations.

Clinical and epidemiological comparison of Rickettsia parkeri rickettsiosis, related to Amblyomma triste and Amblyomma tigrinum, in Argentina.

The aim of this work was to compare the epidemiological and clinical characteristics of Rickettsia parkeri rickettsiosis related to Amblyomma triste and Amblyomma tigrinum ecological regions in Argentina. We reviewed cases of R. parkeri rickettsiosis from 2007 to 2017 evaluated at Muñiz Hospital, directly or through referral. Univariate analysis was used to examine the association between different variables and the disease related by each vector species. The eighteen cases of R. parkeri rickettsiosis included had fever, inoculation eschar and all except one had rash. Regional differences in epidemiological variables were identified, depending on the vector. There was a significantly increased risk of exposure to A. tigrinum in peri-domestic areas (odd ratio 12, p = 0.02), whereas an increased risk of exposure to A. triste was evident in wildlife areas (odd ratio 12, p = 0.02). Seasonality of R. parkeri rickettsiosis differed based on its vector. Cases associated with A. triste occurred predominantly during spring and summer, whereas those associated with A. tigrinum occurred during fall, winter, and springtime. Exanthema was maculopapular (13/18), maculo-vesicular (3/18) or petechial (1/18). No clinical differences were identified depending on the vector.

IFN-γ and IgG responses to Mycobacterium tuberculosis latency antigen Rv2626c differentiate remote from recent tuberculosis infection.

Tuberculin skin test (TST) and IFN-γ release assays are currently used to detect Mycobacterium tuberculosis (Mtb) infection but none of them differentiate active from latent infection (LTBI). Since improved tests to diagnose Mtb infection are required, we studied the immune response to Mtb latency antigen Rv2626c in individuals exposed to the bacteria during different periods. Tuberculosis patients (TB), TB close contacts (CC: subjects exposed to Mtb for less than three months) and healthcare workers (HW: individuals exposed to Mtb at least two years) were recruited and QuantiFERON (QFT) assay, TST and IFN-γ secretion to Rv2626c were analyzed. Twenty-two percent of the individuals assessed had discordant results between QFT and TST tests. Furthermore, QFT negative and QFT positive individuals produced differential levels of IFN-γ against Rv2626c, in direct association with their exposure period to Mtb. Actually, 91% of CC QFT negative subjects secreted low levels of IFN-γ to Rv2626c, whereas 43% of HW QFT negative people produced elevated IFN-γ amounts against Rv2626c. Conversely, 69% of CC QFT positive subjects didn´t produce IFN-γ to Rv2626c. Interestingly, a similar pattern of IgG anti-Rv2626c plasma levels was observed. Therefore, determination of IFN-γ and IgG levels against the dormancy antigen Rv2626c allows to identify established LTBI.

Enfermedad del legionario en Argentina: evolución de la estrategia diagnóstica en el laboratorio / Legionnaires' disease in Argentina: Evolution of the laboratory diagnostic strategy

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.

Caso autóctono de rickettsiosis por Rickettsia parkeri en la Selva Paranaense, Misiones, Argentina / Autochthonous Rickettsia parkeri rickettsiosis in the Paranaense Forest, Misiones, Argentina

Resumen Se informa un caso autóctono de rickettsiosis por Rickettsia parkeri, ocurrido en junio del 2018 en la zona selvática del Parque Provincial Urugua-í, Misiones, Argentina, región sin registros previos de esta enfermedad en humanos. Se describen los aspectos epidemiológicos, ecológicos, clínicos y de laboratorio necesarios para el diagnóstico oportuno y el tratamiento adecuado. Se resalta el hecho de considerar a las rickettsiosis como diagnóstico diferencial ante un paciente con síndrome febril agudo exantemático; el antecedente epidemiológico de exposición al vector característico de la región, garrapatas del género Amblyomma, es un elemento fundamental.

Abstract We report an autochthonous case of Rickettsia parkeri rickettsiosis occurred in June 2018 in a forested area of the Urugua-í Provincial Park, Misiones, Argentina. No previous records of this disease in humans have been previously reported in this region. The epidemiological, ecological, clinical, and laboratory features required for a proper diagnosis and adequate treatment are described here. The fact of considering rickettsiosis as a differential diagnosis in a patient with exanthematic acute febrile syndrome is highlighted, being the epidemiological history of exposure to the vector (ticks of the genus Amblyomma) an essential element.

ARTICLESARS-CoV-2 and Chlamydia pneumoniae co-infection:A review of the literature / Coinfección por Chlamydia pneumoniae y SARS-CoV-2: Una revisión de la literatura

Abstract Bacterial co-pathogens are commonly identified in viral respiratory infections and are important causes of morbid-mortality. The prevalence of Chlamydia (C.) pneumoniae infection in patients infected with SARS-CoV-2 has not been sufficiently studied. The objective of the present review was to describe the prevalence of C. pneumoniae in patients with coronavirus disease 2019 (COVID-19). A search in MEDLINE and Google Scholar databases for English language literature published between January 2020 and August 2021 was performed. Studies evaluating patients with confirmed COVID-19 and reporting the simultaneous detection of C. pneumoniae were included. Eleven articles were included in the systematic review (5 case cross-sectional studies and 6 retrospective studies). A total of 18450 patients were included in the eleven studies. The detection of laboratory-confirmed C. pneumoniae infection varied between 1.78 and 71.4% of the total number of co-infections. The median age of patients ranged from 35 to 71 years old and 65% were male. Most of the studies reported one or more pre-existing comorbidities and the majority of the patients presented with fever, cough and dyspnea. Lymphopenia and eosinopenia were described in COVID-19 co-infected patients. The main chest CT scan showed a ground glass density shadow, consolidation and bilateral pneumonia. Most patients received empirical antibiotics. Bacterial co-infection was not associated with increased ICU admission and mortality. Despite frequent prescription of broad-spectrum empirical antimicrobials in patients with coronavirus 2-associated respiratory infections, there is a paucity of data to support the association with respiratory bacterial co-infection. Prospective evidence generation to support the development of an antimicrobial policy and appropriate stewardship interventions specific for the COVID-19 pandemic are urgently required.

Resumen Los patógenos bacterianos pueden detectarse en las infecciones respiratorias virales y son una causa importante de morbimortalidad. La prevalencia de Chlamydia pneumoniae en pacientes infectados con SARS-CoV-2 ha sido poco estudiada. El objetivo de la presente revisión fue describir la prevalencia de C. pneumoniae en pacientes con enfermedad por coronavirus 2019 (COVID-19). Para ello se realizó una búsqueda bibliográfica en Medline y Google Académico, entre enero de 2020 y agosto de 2021. De la revisión surgieron 11 artículos (cinco estudios de casos transversales y seis estudios retrospectivos), que incluyeron un total de 18.450 pacientes. La detección de C. pneumoniae varió entre el 1,78 y 71,4% del total de las coinfecciones. La media de edad de los pacientes osciló entre los 35 y 71 años y el 65% fueron hombres. En la mayoría de los estudios se informaron comorbilidades preexistentes y la mayor parte de los pacientes presentó fiebre, tos y disnea. Además, se describió linfopenia y eosinofilopenia en pacientes con COVID-19 coinfectados. La principal manifestación en la tomografía computarizada fue densidad de vidrio esmerilado, consolidación y neumonía bilateral. La mayoría de los pacientes recibió antibióticos de manera empírica. La coinfección bacteriana no se asoció con un aumento de ingresos en cuidados intensivos ni mortalidad. A pesar de la prescripción de antimicrobianos empíricos en pacientes con infecciones respiratorias asociadas a coronavirus existen pocos reportes de detección de coinfección bacteriana. Es necesario generar evidencia para el desarrollo de políticas antimicrobianas e intervenciones de administración apropiadas y específicas en la pandemia de COVID-19.

Estudio comparativo del rendimiento de GeneXpertMTB/RIF en lavado broncoalveolar frente al lavado bronquial en pacientes con sospecha clínica de tuberculosis / Comparative study of the performance of GeneXpert MTB/RIF in bronchoalveolar lavage compared to bronchial lavage in patients with clinical suspicion of tuberculosis

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.

Comparative study of the performance of GeneXpert MTB/RIF in bronchoalveolar lavage compared to bronchial lavage in patients with clinical suspicion of tuberculosis

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.

Bacteriemia por Helicobacter cinaedi: presentación de los primeros casos descritos en Argentina / Helicobacter cinaedi bacteremia: Presentation of the first cases reported in Argentina

Se presentan 2 casos de bacteriemia por Helicobacter cinaedi. El primero se diagnosticó en un varón de 76 años y resultó secundario a la colocación de un acceso vascular; el segundo correspondió a un lactante febril de 37 días de vida, asociado a un cuadro de gastroen-terocolitis aguda. H. cinaedi es un microorganismo que presenta dificultad para desarrollarse en diferentes medios de cultivo y lograr su identificación a nivel de especie. En ambos casos fue fundamental la observación microscópica en fresco de las botellas de hemocultivo, la utilización de la espectrometría de masas y la posterior secuenciación del gen hsp60 para llegar a esa instancia. En los últimos anos se han informado infecciones por H. cinaedi con frecuencia creciente en otras partes del mundo. En este trabajo presentamos los primeros casos de bacteriemia por H. cinaedi documentados en Argentina.

Two cases of bacteremia caused by Helicobacter cinaedi are presented. The first case was diagnosed in a 76-year-old male patient, and was secondary to a vascular access device placement; the second case corresponded to a febrile infant of 37 days of life, and was associated with acute gastroenteritis. H. cinaedi is a microorganism difficult to grow in different culture media and also to identify to species level. In both cases, the microscopic observation of blood culture bottles, the use of mass spectrometry and the subsequent sequencing of the hsp60 gene were essential. In the recent literature, H. cinaedi infections are being reported more frequently. In this report we present the first documented cases of bacteremia caused by H. cinaedi in Argentina.

Fiebre manchada en Argentina. Descripción de dos casos clínicos / Spotted fever in Argentina. Description of two clinical cases

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.

Desarrollo y evaluación de una base de datos in house para la identificación rápida de Burkholderia contaminons por EM MALDI-TOF / Development and evaluation of an in-house database for quick identification of Burkholderia contaminans by MALDI-TOF MS

La espectrometría de masas (EM) (matrix assisted laser desorption ionization-time of flight) MALDI-TOF demostró ser una herramienta robusta para la identificación de numerosos grupos taxonómicos. No obstante, presenta limitaciones. Una ventaja clave de la técnica es la flexibilidad para la incorporación de espectros proteicos de microorganismos ausentes en la base de datos comercial. Dada la prevalencia de Burkholderia contaminans en los pacientes fibroquísticos en Argentina, y a que en ellos es crucial el diagnóstico microbiológico rápido y confiable, la EM MALDI-TOF surge como una herramienta estratégica. El objetivo del trabajo fue desarrollar una base de datos adicional con espectros peptídicos de aislamientos de referencia de B. contaminans. La misma demostró ser exitosa para la identificación del 97% de los aislamientos analizados. Por lo cual la EM MALDI-TOF con la base de datos extendida resultó ser una herramienta útil para la identificación y diferenciación de otras especies relacionadas a B. contaminans.

MALDI-TOF (matrix assisted laser desorption ionization-time of flight) mass spectrometry (MS) proved to be a robust tool for the identification of numerous taxonomic groups. However, it has limitations. A key advantage of this technique is the flexibility for the incorporation of protein profiles of microorganisms not included in the commercial database. Due to the prevalence of Burkholderia contaminans in fibrocystic patients in Argentina and the fact that rapid and reliable microbiological diagnosis is crucial in them, MALDI-TOF MS emerges as a strategic tool. The aim of this work was to develop an additional database with peptide spectra of reference isolates of B. contaminans. This database demonstrated to be successful for the identification of 97% of the isolates analyzed. Therefore, MALDI-TOF MS with the extended database was a useful tool for the identification and differentiation of other related species to B. contaminans.

Diagnóstico de infección tuberculosa latente: comparación de la prueba de tuberculina y el quantiferon-tb gold plus en contactos domiciliarios de la Ciudad de Buenos Aires / Diagnosis of Latent Tuberculosis Infection: Comparison between the Tuberculin Test and Quantiferon-TB Gold Plus in Household Contacts from the City of Buenos Aires

La estrategia de control epidemiológico de la tuberculosis (TB) incluye tanto el diagnóstico y tratamiento precoz de los pacientes bacilíferos, como la identificación de aquellos con infección tuberculosa latente (ITBL) quienes representan el reservorio patógeno en la población. Objetivo: Comparar los resultados obtenidos utilizando la prueba de tuberculina (PPD) y el QuantiFERON-TB Gold Plus (QTF) en un grupo de contactos domiciliarios de pacientes con TB pulmonar bacilífera, de la Ciudad de Buenos Aires. Se utilizaron dos puntos de corte para considerar la PPD positiva: ≥ 5 mm (PPD-5) y ≥ 10 mm (PPD-10). Materiales y métodos: Se extrajeron muestras de sangre para QTF en contactos domiciliarios de pacientes con TB bacilífera, seguido inmediatamente de la aplicación de PPD. Se consideró al QTF como la prueba de referencia a partir de la cual comparar la PPD calculando la sensibilidad (S), especificidad (E), valor predictivo positivo (VPP), valor predictivo negativo (VPN) y coeficiente de correlación Kappa. Resultados: Se incluyeron 48 contactos (33 mujeres, 69%), edad 38.8 ± 19 años, 27 (56%) argentinos, 18 (38%) bolivianos y 3(6%) peruanos, correspondientes a 37 casos de TB. Un solo contacto refirió no haberse aplicado la BCG, en 44 se objetivó la cicatriz. El QTF resultó positivo en 23 (47.9%) e indeterminado en 2 casos (4.2%). Excluyendo del análisis a los indeterminados, no hubo diferencias significativas entre contactos con QTF positivo y negativo al considerar la edad (33.8 ± 16 vs 42.1 ± 20 años), nacionalidad: argentinos (12 de 26, 46%) vs extranjeros (11 de 20, 55%) y sexo: mujeres (18 de 32, 56%) vs hombres (5 de 14, 36%). Utilizando PPD-5 hubo 28 (60.9%) positivos y 13 (28.3%) con PPD-10. Comparando PPD-5 vs PPD-10: S = 73.9 vs 34.8%, E = 52.2 vs 78.3%, VPP = 60.1 vs 61.5% y VPN = 66.7 vs 54.5%. Los resultados coincidentes (positivos y negativos) entre QTF y PPD fueron 29 (63%) para PPD-5 y 26 (56.5%) con PPD-10. Expresados con el coeficiente Kappa muestran concordancia débil (0.261) e insignificante (0.130), respectivamente. Conclusiones: considerando al QTF como el método de referencia por su mayor especificidad, la PPD-5, aunque menos específica, resultó más sensible que la PPD-10 para diagnosticar infección tuberculosa latente en el grupo de contactos domiciliarios estudiados