Encefalomielitis aguda diseminada por Mycoplasma pneumoniae en un niño previamente sano / Acute disseminated encephalomyelitis due to Mycoplasma pneumoniae in a previously healthy boy

Se presenta el caso de un niño de 5 años sin antecedentes de enfermedad, que se internó en terapia intensiva por convulsiones tónico-clónicas focalizadas en la cara y en el hemicuerpo derecho, con documentación de temperatura axilar de 37,4°C. Se descartó la presencia de gérmenes comunes y la etiología viral a través de estudios de muestras de líquido cefalorraquídeo (LCR). Se sospechó la presencia de Mycoplasma pneumoniae por comprobarse inmunofluorescencia positiva en suero para anticuerpos de clase IgM. El diagnóstico se confirmó mediante la detección del ADN de dicho patógeno sobre la biopsia cerebral efectuada por el método de la reacción en cadena de la polimerasa (PCR) y una histología compatible con encefalomielitis aguda diseminada. El paciente recibió tratamiento con claritromicina y su evolución fue favorable. Al menos dentro de nuestros conocimientos, este es el primer caso en el que se detectó ADN de M. pneumoniae en una biopsia cerebral por el método de PCR.

We present here the case of a previously healthy 5 year-old boy hospitalized in an intensive care unit due to tonic-clonic seizures focused on the face and right side of the body, and axillary temperature of 37.4 °C. Common bacterial and viral etiology was ruled out through studies of cerebrospinal fluid (CSF) samples. Mycoplasma pneumoniae was suspected by a positive immunofluorescence serum test for IgM class antibodies. Finally, with a brain biopsy, M. pneumoniae was confirmed by polymerase chain reaction (PCR) and acute disseminated encephalomyelitis by pathological anatomy. The patient was treated with clarithromycin and had an uneventful evolution. At least to our knowledge, this is the first case in which M. pneumoniae DNA was detected by PCR in a brain biopsy.

[Acute disseminated encephalomyelitis due to Mycoplasma pneumoniae in a previously healthy boy]. / Encefalomielitis aguda diseminada por Mycoplasma pneumoniae en un niño previamente sano.

We present here the case of a previously healthy 5 year-old boy hospitalized in an intensive care unit due to tonic-clonic seizures focused on the face and right side of the body, and axillary temperature of 37.4°C. Common bacterial and viral etiology was ruled out through studies of cerebrospinal fluid (CSF) samples. Mycoplasma pneumoniae was suspected by a positive immunofluorescence serum test for IgM class antibodies. Finally, with a brain biopsy, M. pneumoniae was confirmed by polymerase chain reaction (PCR) and acute disseminated encephalomyelitis by pathological anatomy. The patient was treated with clarithromycin and had an uneventful evolution. At least to our knowledge, this is the first case in which M. pneumoniae DNA was detected by PCR in a brain biopsy.

Virological surveillance and antiviral resistance of human influenza virus in Argentina, 2005–2008 / Vigilancia virológica y resistencia a los antivíricos del virus de la gripe humana en la Argentina, 2005–2008

Objective. To describe the virological characteristics of the influenza strains circulating in Argentina in 2005–2008 and to assess the prevalence of antiviral resistance. Methods. On the basis of their geographical spread and prevalence, influenza A and B isolates grown in Madin–Darby canine kidney cells were selected after antigenic and genomic characterization to be analyzed for antiviral resistance by enzymatic assay and pyrosequencing. Amantadine susceptibility was evaluated by pyrosequencing for known resistance markers on 45 strains of influenza A. Susceptibility to oseltamivir and zanamivir was evaluated by enzymatic assay of 67 influenza A and 46 influenza B strains, some of which were further analyzed by sequencing the neuraminidase gene. Results. Resistance to amantadine was observed only on A(H3N2) strains (29/33); all of them carried the mutation S31N in their M2 sequence. Oseltamivir resistance was observed in 12 (34.3%) of the 35 A(H1N1) strains from 2008; all of them carried the mutation H275Y in their neuraminidase sequence. All these viruses remained sensitive to zanamivir. Conclusions. This study describes a high incidence of amantadine-resistant influenza A(H3N2) viruses since 2006 and an unprecedented increase in oseltamivir resistance detected only in influenza A(H1N1) viruses isolated in 2008. Influenza A and B viruses were more sensitive to oseltamivir than to zanamivir, and influenza A viruses were more sensitive to both neuraminidase inhibitors than the influenza B viruses. The national data generated and analyzed in this study may help increase knowledge about influenza antiviral drug resistance, which is a problem of global concern.

Objetivo. Describir las características virológicas de las cepas de virus de la gripe que circulaban en la Argentina entre el 2005 y el 2008, y evaluar la prevalencia de la resistencia a los antivíricos. Métodos. Según su diseminación geográfica y su prevalencia, se seleccionaron aislados de gripe A y B cultivados en células renales caninas de Madin-Darby después de su caracterización antigénica y genómica, y se analizó su resistencia a los antivíricos mediante análisis enzimático y pirosecuenciación. La sensibilidad a la amantadina se evaluó por pirosecuenciación para los marcadores conocidos de resistencia en 45 cepas de gripe A. La sensibilidad al oseltamivir y al zanamivir se evaluó mediante análisis enzimático de 67 cepas de gripe A y 46 cepas de gripe B, algunas de las cuales se analizaron en mayor profundidad mediante la secuenciación del gen de la neuraminidasa. Resultados. Se observó resistencia a la amantadina solo en las cepas de gripe A (H3N2) (29/33); todas ellas tenían la mutación S31N en su secuencia de M2. Se observó resistencia al oseltamivir en 12 (34,3%) de las 35 cepas de gripe A (H1N1) aisladas en el 2008; todas ellas tenían la mutación H275Y en su secuencia de neuraminidasa. Todos estos virus conservaron su sensibilidad al zanamivir. Conclusiones. En este estudio se describe una incidencia elevada del virus de la gripe A (H3N2) resistente a la amantadina desde el 2006 y un aumento sin precedentes de la resistencia al oseltamivir detectada solo en los virus de la gripe A (H1N1) aislados en el 2008. Los virus de la gripe A y B fueron más sensibles al oseltamivir que al zanamivir y los virus de la gripe A fueron más sensibles a ambos inhibidores de la neuraminidasa que los virus de la gripe B. Los datos nacionales generados y analizados en este estudio pueden ayudar a aumentar los conocimientos acerca de la resistencia a los fármacos antivíricos dirigidos contra el virus de la gripe, lo que es un motivo de preocupación mundial.

Exceso de mortalidad asociada a influenza en Argentina: 1992-2002 / Influenza associated excess mortality in Argentina: 1992-2002

Objective: To describe the effect of influenza on mortality in Argentina, from 1992 to 2002. Method: In order to fulfill this objective, influenza associated excess mortality was determined by the application of ARIMA method to mortality data for pneumonia and influenza and for all causes. Results: Excess mortality was only detected during subtype A/H3N2 seasons. The model yielded about 31,240 excess mortality for all causes. Pneumonia deaths contributed in about 15 percent. Approximately 80-95 percent of pneumonia and influenza excess mortality was restricted to persons > 64 years old. Conclusions: These estimations show that the virus circulation has had an important influence on mortality, increasing the number of deaths, especially in elderly population. The aging of the population reinforces the need of preventing strategies, including vaccination programs with high coverage in elderly population.

Objetivo: Se describe el efecto de las epidemias de influenza sobre la mortalidad en Argentina desde 1992 a 2002. Metodología: Se estimaron los excesos de muertes asociados a influenza mediante la aplicación del método ARIMA a los datos de mortalidad por neumonía e influenza y todas las causas. Resultados. Sólo se detectaron excesos de muerte durante las estaciones con predominio del subtipo A/H3N2. Se esti maron alrededor de 31.240 excesos de muertes por todas las causas. Las muertes por neumonía contribuyeron en alrededor del 15 por ciento. Alrededor de 80 a 95 por ciento de los excesos de muerte por neumonía e influenza ocurrieron en personas de > 64 años. Conclusiones: Estas estimaciones evidencian que la circulación del virus ha ejercido una importante influencia sobre la mortalidad total, incrementando el número de muertes fundamentalmente en personas de edad. El envejecimiento de la población enfatiza la necesidad de medidas de prevención, incluyendo programas de vacunación con alta cobertura en personas de mayor edad.

Infección Respiratoria Aguda por metapneumovirus humano en Ushuaia, Argentina: descripción del primer caso / Acute lower respiratory infection by human metapneumovirus in Ushuaia, Argentina: description of the first patient

RESUMEN Hacia fines del año 2003, en la ciudad de Ushuaia resultó llamativa la cantidad de niños internados con cuadros respiratorios graves y estudios virológicos negativos. Sobre la base de publicaciones acerca de la circulación de un nuevo virus respiratorio, metapneumovirus humano, se decidió investigar su presencia en tres muestras respiratorias de niños internados con infección respiratoria aguda en el Hospital Regional de Ushuaia. Los aspirados nasofaríngeos, previamente negativos para los virus respiratorios comunes por la técnica de inmunofluorescencia, fueron estudiados mediante la técnica de transcripción inversa y amplificación genómica por reacción en cadena de la polimerasa para metapneumovirus humano. Una de las muestras resultó positiva para metapneumovirus humano. En ninguno de los pacientes se detectaron anticuerpos de clase IgM para Chlamydia spp y Mycoplasma pneumoniae, por la técnica de inmunofluorescencia. La descripción del presente caso enfatiza la necesidad de ampliar el espectro diagnóstico en niños internados que resulten negativos para los virus respiratorios más comunes.

Antigenic and genomic relation between human influenza viruses that circulated in Argentina in the period 1995-1999 and the corresponding vaccine components.

BACKGROUND: The analysis of epidemic influenza virus has been focused on antigenic and genomic characterization of the hemagglutinin (HA) glycoprotein in order to detect new variants for the recommendation of the vaccine strains in each season. Since October 1998, WHO organized a second meeting to evaluate the vaccine formula for the southern hemisphere. OBJECTIVES: (a) Present the antigenic and genomic characterization of influenza strains obtained from the Argentina surveillance network, (b) compare between strains collected in Argentina and other countries with the vaccine formula strains used in each season. STUDY DESIGN: Influenza strains were collected during a 5-year period (1995-1999). Initially, laboratory diagnosis was done by immunofluorescence (IF) assay on clinical samples, followed by viral isolation in Madin-Darby canine kidney (MDCK) cells. The isolates were characterized antigenically by hemagglutination-inhibition (HI) assay with post-infection ferret antisera. The genomic characterization consisted on RT-PCR followed by sequencing of the HA1 portion of the HA gene. The comparison between reference and circulating strains was analyzed by the construction of phylogenetic trees. RESULTS: The H3N2 circulating strains matched the corresponding vaccine component only in 1999, the first year when a vaccine recommended specifically for the southern hemisphere was used. Besides, H1N1 circulating strains matched the corresponding vaccine component only in 1998. Regarding to influenza B, only in 1995, the circulating strains showed no match to the B vaccine component. CONCLUSIONS: The results showed the usefulness of an intensified influenza laboratory surveillance to access the correct vaccine and the importance of having the necessary tools to characterize the circulating strains.

[Community-acquired pneumonia in patients in 2 hospital populations]. / Neumonía adquirida en la comunidad en dos poblaciones hospitalarias.

Patients hospitalized with community acquired pneumonia were studied prospectively in two hospitals located in the surroundings of Buenos Aires city. Fifty two patients from General Hospital Manuel Belgrano (HMB) were included from March 1998 to February 1999 and 23 patients from Hospital Dr A. Cetrangolo (HCET) for respiratory disease, were included from June 2000 to May 2001. Patients with lung tuberculosis, lung neoplasia and HIV infection were excluded. Clinical background, signs and symptoms were recorded. Microbiological examinations performed included bacteria, respiratory viruses and mycobacteria. Studies for "atypical" bacteria (Chlamydia spp., Coxiella burnetii, Mycoplasma pneumoniae and Legionella spp.) were carried out by serological methods. No differences in age and gender were observed between both groups. Most frequently observed comorbidities in the HMB group included COPD, diabetes and cardiac failure while in the HCET group these were COPD, asthma and lung fibrosis. Etiology was established in 48% and 65.2% of the patients in the first and second group, respectively. Most frequent agents were Mycoplasma pneumoniae, Streptococcus pneumoniae, influenza A and Legionella spp.; the last one was detected in 12% of the patients. Most of these patients were from HMB and presented a good outcome. Mortality was similar in both groups (13.3%). In the HBM group it was related to the presence of comorbidities in 7 out of 8 cases, and in the HCET group it was a consequence of the worsening of their chronic respiratory failure.

Neumonia adquirida en la comunidad en dos poblaciones hospitalarias / Community-acquired pneumonia in patients from two different hospitals

Patients hospitalized with community acquired pneumonia were studied prospectively in two hospitals located in the surroundings of Buenos Aires city. Fifty two patients from General Hospital Manuel Belgrano (HMB) were included from March 1998 to February 1999 and 23 patients from Hospital Dr A. Cetrangolo (HCET) for respiratory disease, were included from June 2000 to May 2001. Patients with lung tuberculosis, lung neoplasia and HIV infection were excluded. Clinical background, signs and symptoms were recorded. Microbiological examinations performed included bacteria, respiratory viruses and mycobacteria. Studies for "atypical" bacteria (Chlamydia spp., Coxiella burnetii, Mycoplasma pneumoniae and Legionella spp.) were carried out by serological methods. No differences in age and gender were observed between both groups. Most frequently observed comorbidities in the HMB group included COPD, diabetes and cardiac failure while in the HCET group these were COPD, asthma and lung fibrosis. Etiology was established in 48% and 65.2% of the patients in the first and second group, respectively. Most frequent agents were Mycoplasma pneumoniae, Streptococcus pneumoniae, influenza A and Legionella spp.; the last one was detected in 12% of the patients. Most of these patients were from HMB and presented a good outcome. Mortality was similar in both groups (13.3%). In the HBM group it was related to the presence of comorbidities in 7 out of 8 cases, and in the HCET group it was a consequence of the worsening of their chronic respiratory failure

Efecto de las epidemias de influenza sobre la mortalidad en Santa Fe, Argentina, en 1992-1999 / Effect of influenza epidemics on mortality in Santa Fe, Argentina, during 1992-1999

Objetivos. Descubrir el efecto de las epidemias de influenza sobre la mortalidad y determinar el criterio más apropiado para predecir la magnitud de ésta, a fin de brindar un método que alerte precozmente de la gravedad de una epidemia de influenza. Métodos. El estudio se realizó en La Capital, departamento de la provincia de Santa Fe, Argentina, durante el período de 1992­1999. Para lograr el primer objetivo se llevó a cabo un análisis retrospectivo de los datos de mortalidad por neumonía e influenza en personas mayores de 65 años, utilizando el método autorregresivo integrado de promedios móviles (ARIMA, por el inglés auto-regressive integrated moving averages). Con él se determinó el exceso de mortalidad atribuible a las epidemias de influenza. A fin de alcanzar el segundo objetivo, se efectuó un análisis de regresión para estudiar la relación entre la morbilidad semanal por influenza y la mortalidad mensual por neumonía o influenza en personas mayores de 65 años. La morbilidad se expresó mediante tres medidas resumen calculadas a partir del número de casos notificados durante las primeras 35 semanas epidemiológicas del año (ocho primeros meses calendario): la suma total de los casos notificados semanalmente, su desviación estándar y su número en la semana invernal en que hubo más casos. En este análisis se incluyeron el tipo y el subtipo de influenza. Estos cuatro parámetros (el tipo y subtipo de influenza, junto con una de las tres medidas resumen) se compararon entre sí con respecto a su poder para explicar la mortalidad registrada durante los primeros ocho meses del año. Resultados. Se produjeron epidemias en la estación invernal de 1993, 1995, 1999 y en la primavera de 1997, estaciones en las que se identificó un exceso de muertes asociado a la circulación de una cepa predominante del virus de la influenza de tipo A, la H3N2. Este patrón de exceso de mortalidad es típico de cepas de la influenza del tipo A (H3N2). Durante los inviernos de 1994, 1996 y 1998 no se produjeron epidemias a pesar de haber estado en circulación el virus de la influenza de tipo A (H3N2). En las estaciones invernales relacionadas conla circulación de cepas de la influenza de los tipos A (H1N1) (1992) y B (1997), cuyos patrones suelen asociarse a una baja mortalidad, tampoco se detectó un exceso de muertes. Conclusiones. El número de casos de influenza semanales notificados durante el pico de la estación invernal resulta el mejor parámetro para estimar el impacto de la influenza sobre elnúmero de defunciones

Objectives. To define the effect of influenza epidemics on mortality and to establish the best criterion for predicting mortality so as to provide a method for advance warning of the severity of an influenza epidemic. Methods. The study was carried out in La Capital, a department in Santa Fe province, Argentina, during 1992­1999. In order to fulfill the first objective, a retrospective analysis was performed with mortality data for pneumonia and influenza in persons over 65 years of age, using the auto-regressive integrated moving averages (ARIMA). The latter were used to determine the excess mortality attributable to influenza epidemics. In order to attain the second objective, a regression analysis was performed so as to study the correlation between weekly morbidity from influenza and monthly mortality from pneumonia or influenza in personas over 65. Morbidity was expressed in terms of three summary measures which were derived from the number of cases of influenza that were reported during the first 35 weeks of the year: the sum total of all cases reported weekly, their standard deviation, and the maximum number of cases in any given week. We included in the analysis the type and subtype of influenza. These four parameters (type and subtype of influenza, along with one of the three summary measures) were compared among themselves in terms of their ability to explain the mortality observed during the first eight months of the year. Results. Epidemics occurred during the winters of 1993, 1995, and 1999 and in the spring of 1997. During those seasons, excess deaths were observed in connection with the circulation of a predominant strain of influenza virus, type A (H3N2). There were no epidemics in the winter months of 1994, 1996, and 1998, despite the circulation of this viral strain. During the winters in which influenza virus strains A (H1N1) and B were in circulation (1992 and 1997, respectively)­both are associated with low mortality figures­no excess deaths were detected. Conclusions. The number of weekly cases of influenza reported during the peak of the winter season is the best criterion for predicting how much excess mortality can be attributed to the epidemic

Evaluacion etiologica y clinica de infecciones respiratorias agudas bajas en una poblacion infantil / Etiological and clinical evaluation of low acute respiratory infections in children

Se estudió el agente etiológico viral y los principales parámetros clínicos y epidemiológicos de las infecciones respiratorias agudas bajas (IRAB) en una población de 80 niños menores de 4 años internados con diagnóstico de neumonía, bronquiolitis, neumonitis u otros. En los 33 casos confirmados de etiología viral, que constituyeron el 41,3 por ciento del total, el diagnóstico más frecuente fue la bronquiolitis, en tanto que la neumonía lo fue en aquélios en que no se demostró presencia viral. El 63,8 por ciento de la población estudiada eran menores de 6 meses y el grupo de 2 a 5 meses presentó el más alto porcentaje de casos de etiología viral. Predominó en todo el grupo el Virus Sincicial Respiratorio (RSV) 78,8 por ciento (26 casos), seguido por Adenovirus 9,1 por ciento (3 casos), Influenza 6,1 por ciento (2 casos) y Parainfluenza 3 por ciento (l caso). Hubo sólo l caso de infección por 2 virus (RSV e Influenza A). El pico máximo de incidência fue en el mes de junio (comienzo del invierno). La mayoría de los pacientes 77,5 por ciento (62 casos) permaneció internado menos de 10 días. La mortalidad global fue del 7,5 por ciento. La utilización de la asistencia respiratoria mecánica en las bronquiolitis severas reduce la tasa de mortalidad, en tanto que las neumonías por Adenovirus presentan una evolución tórpida con complicaciones. Se estableció un tratamiento antibiótico en el 61,2 por ciento (49/80) de los pacientes. El 34,7 por ciento (l7/49) de los pacientes tratados tuvo un diagnóstico virológico positivo. La disponibilidad del diagnóstico virológico rápido puede contribuir a la disminución del uso innecesario de los antibióticos.

Detección de una nueva variación genómica de Adenovirus 7 asociada a infecciones severas del tracto respiratorio inferior / Detection of a new genomic variation of Adenovirus 7 associated to severe infections of the lower respiratory tract

We report a new genomic variation of Adenovirus 7, associated to severe infections of the lower respiratory tract isolated during September 1990, from children under 3 years of age and living in Buenos Aires city. The restriction analysis with the BamHI, BglI, BglII and SmaI restriction endonucleases demonstrated that the new variation is highly related to the recently described Adenovirus 7h.