Efectividad y seguridad en vida real de nivolumab en el tratamiento del cáncer de pulmón no microcítico en segunda línea / Real-life efficacy and safety of nivolumab in the treatment of second-line non-small cell lung cáncer

Objetivo: Evaluar la efectividad y el perfil de seguridad de nivolumab utilizado en segunda línea en el tratamiento del cáncer de pulmón no microcítico en la práctica clínica real. Material y métodos: Estudio observacional retrospectivo en pacientes con cáncer de pulmón no microcítico en tratamiento con nivolumab en segunda línea entre diciembre-2015 y noviembre-2019. Se evaluó la respuesta mediante criterios RECIST v1.1 (Response Evaluation Criteria in Solid Tumors). Variables principales de efectividad: tasa de respuesta objetiva (TRO) y supervivencia global (SG); variables secundarias: supervivencia libre de progresión (SLP). Los posibles factores predictores de respuesta (edad, sexo, histología y ECOG-PS -Eastern Cooperative Oncology Gropup-Performance status-) se analizaron mediante un modelo de riesgos proporcionales de Cox para la SG Y SLP, y odds ratio para TRO. La seguridad se evaluó mediante la aparición de eventos adversos (EAs) y su grado según CTCEA v5.0 (Criterios Comunes de Terminología para Eventos Adversos).Resultados: Se incluyeron 48 pacientes, con una mediana de edad de 65,5 años (rango 46-83), mayoritariamente hombres (85,5%), ECOG-PS 0-1 (85%). En cuanto a la efectividad, TRO=27% (IC95% 14,04-40,12), mediana SG 13,01 meses (IC95% 7,67-18,36) y SLP 5,29 meses (IC95% 3,53-7,05). El sexo se identificó como factor predictor de mejor respuesta en términos de TRO. Un 10% de los pacientes presentaron al menos un EA G3-G4.Conclusiones: Nivolumab tuvo una efectividad ligeramente superior a la demostrada en ensayos clínicos. La seguridad del tratamiento fue aceptable, posicionando nivolumab como una alternativa válida en el tratamiento de cáncer de pulmón no microcítico en segunda línea. (AU)

Objective: To evaluate the effectiveness and safety profile of nivolumab used in second line for the treatment of non-small cell lung cancer in real clinical practice. Material and methods: Retrospective observational study was carried off in patients with non-small cell lung cancer treated with nivolumab in the second line between December 2015 and November 2019. The response was evaluated using RECIST v1.1 criteria. Main survival variables: objective response rate (ORR) and overall survival (OS); secondary variables: progression-free survival (PFS). The possible predictive response factors (age, sex, histology and ECOG-PS) were analyzed using a Cox proportional hazard model for survival, and odds ratio for the objective response rate. The safety was evaluated through the occurrence of adverse events (AD) and their degree according to CTCEA v5.Results: 48 patients were included, median age of 65.5 years (range 46-83), mostly men (85.5%), ECOG-PS 0-1 (85%). Regarding effectiveness, ORR=27% (95% CI 14.04-40.12), median SG 13.01 months (95% CI 7.67-18.36) and SLP 5.29 months (95% CI 3.53-7.05). Sex was identified as a predictor of better response in terms of ORR. EA G3-G4 appeared in 10% of patients.Conclusions: Nivolumab had a slightly higher effectiveness than demonstrated in clinical trials. The safety of the treatment was acceptable, positioning nivolumab as a valid alternative in the treatment of non-small cell lung cancer in second line. (AU)

Resultados en vida real de los antivirales de acción directa en el tratamiento de la hepatitis C crónica / Real life results of direct acting antiviral in hepatitis C treatment

Objetivo: Los antivirales de acción directa han logrado tasas de respuesta viral sostenida muy elevadas desde su comercialización. El objetivo de este trabajo fue el análisis de la efectividad y seguridad de los antivirales de acción directa en pacientes infectados por el virus de la hepatitis C crónica.Métodos: Se incluyeron pacientes infectados con el virus de la hepatitis C (VHC) y coinfectados por VHC y virus de la inmunodeficiencia humana (VIH) que iniciaron tratamiento con antivirales de acción directa entre 2015-2019. Como variable de efectividad se midió la respuesta viral sostenida.Resultados: Se incluyeron 303 pacientes, 235 (77,56%) monoinfectados y 68 (22,44%) coinfectados. El genotipo de virus más prevalente fue el 1 en ambos grupos. La proporción de cirróticos fue superior en la población monoinfectada 38,3% vs. 20,6%; p=0,047). De los 303 pacientes, a 279 se le analizó la carga viral a las 12 semanas de tratamiento; un 97,8% (273/279) alcanzaron respuesta viral sostenida, confirmándose 6 fracasos virológicos. En un análisis de subgrupos, en la mayoría de grupos según la presencia o no de cirrosis, la coinfección VIH y el genotipo, la efectividad se situó próxima o por encima del 90%. El tratamiento fue seguro, con toxicidad leve y sólo una suspensión de tratamiento. Se detectaron interacciones medicamentosas potenciales en un 20% de los pacientes.Conclusiones: Los antivirales de acción directa presentaron una efectividad elevada, igual e incluso superior a la descrita en los ensayos clínicos, e incluso en subpoblaciones difíciles de tratar. (AU)

Objetive: Direct-acting antivirals have achieved high sustained viral response rates since their commercialization. The main objective of this study was the analysis of the efficacy and safety of direct-acting antivirals in patients infected with the chronic hepatitis C virus.Methods: Patients infected with hepatitis C virus (HCV) and co-infected with HCV and human immunodeficiency virus (HIV) who started treatment with direct-acting antiviral drugs between 2015-2019 were included. The sustained viral response was measured as the effectivity variable.Results: 303 patients were included, 235 (77.56%) were monoinfected and 68 (22.44%) were co-infected. Genotype 1 virus was the most prevalent 1 in both groups. The proportion of cirrhotic was higher in the monoinfected population (38.3% vs. 20.6%; p=0.047). Of the 303 patients, 279 pacients had viral load analysis at 12 weeks of treatment, 97.8% (273/279) achieved sustained viral response and 6 virological failures were confirmed. In a subgroup analysis, the majority of the groups, regardless of the presence or not of cirrhosis, HIV coinfection or genotype, the efficacy was close to or above 90%. The treatment was safe, with mild toxicity and only one treatment suspension. Potential drug interactions were detected in 20% of patients.Conclusions: Direct-acting antivirals with a high efficacy, equal to or greater than that described in clinical trials, and even with subpopulations difficult to treat. (AU)

[Diagnosis of bacterial vaginosis in women attending a family planning clinic in the Metropolitan Region of Chile]. / Diagnóstico de vaginosis bacteriana en un consultorio de planificación familiar de la Región Metropolitana, Chile.

In order to determine the prevalence of bacterial vaginosis (BV) among women attending a family health Center and to evaluate the accuracy of Amsel's diagnostic procedure relative to Nugent scoring for diagnosing this condition, we obtained vaginal specimens from 100 women under 50 years attending a FPC from April to November of 2006. Women were enrolled consecutively on a schedule basis and were not selected by symptoms of genital infection. VB was diagnosed in 32% women, without significant differences by age (p=0,114). 87.5% women declared one sexual partner in the last 6 months. The Amsel's method had a sensitivity of 62.1%, and a specificity of 92.3%, with positive and negative predictive values of 81.8% and 83.3% respectively, being the presence of clue cells the most accurate parameter. Nevertheless, the lack of microscopes in the clinical practice limits the use of the Amsel's criteria. In conclusion, VB is a prevalent infection in the study population, being not associated with age or sexual activity. Diagnosis should be performed by the Nugent method.

Diagnóstico de vaginosis bacteriana en un consultorio de planificación familiar de la Región Metropolitana, Chile / Diagnosis of bacterial vaginosis in women attending a family planning clinic in the Metropolitan Region of Chile

In order to determine the prevalence of bacterial vaginosis (BV) among women attending a family health Center and to evaluate the accuracy of Amsel's diagnostic procedure relative to Nugent scoring for diagnosing this condition, we obtained vaginal specimens from 100 women under 50 years attending a FPC from April to November of 2006. Women were enrolled consecutively on a schedule basis and were not selected by symptoms of genital infection. VB was diagnosed in 32 percent> women, without significant differences by age (p = 0,114). 87.5 percent> women declared one sexual partner in the last 6 months. The Amsel's method had a sensitivity of 62.1 percent>, and a specificity of 92.3 percent>, with positive and negative predictive values of 81.8 percent> and 83.3 percent> respectively, being the presence of clue cells the most accurate parameter. Nevertheless, the lack of microscopes in the clinical practice limits the use of the Amsel's criteria. In conclusion, VB is a prevalent infection in the study population, being not associated with age or sexual activity. Diagnosis should be performed by the Nugent method.

Con el objeto de determinar la prevalencia de vaginosis bacteriana (VB) en mujeres consultantes en un Centro de Salud Familiar (CESFAM) y evaluar la utilidad diagnóstica de los criterios de Amsel, en comparación con el método de Nugent, se tomaron muestras vaginales de 100 mujeres menores de 50 años, entre abril y noviembre de 2006. Las mujeres fueron enroladas consecutivamente sin seleccionar por síntomas. Se detectó VB en 32 por ciento mujeres, sin encontrar diferencias significativas por edad (p = 0,114). El 87,5 por ciento> de las mujeres declaró pareja sexual única en los últimos 6 meses. El método de Amsel tuvo 62,l por cientoo, de sensibilidad, 92,3 por ciento> de especificidad y valores predictores positivo y negativo de 81,8 y 83,3 por ciento respectivamente. La presencia de "clue cells" fue el mejor parámetro del método de Amsel, lo que está limitado por la falta de microscopios en la práctica clínica. En conclusión, VB es una infección prevalente en la población en estudio, no se asocia a edad o actividad sexual, recomendándose para su diagnóstico el método de Nugent.

Diagnóstico microbiológico de las infecciones de transmisión sexual (ITS): Parte 1. ITS no virales / Microbiological diagnosis of sexually transmitted infections (STI): Part 1. Non-viral STI

Non-viral sexually transmitted infections (STI) are an important cause of physical, psychological and social distress, have severe consequences for women's reproductive health and may be transmitted to the newborn child. These infections are also risk factors for the acquisition and transmission of HIV and other STI, and for premature labor. In the last years we have observed a gradual decrease in the national incidence of gonorrhea. The implementation of a screening program in our country for Chlomydia trachomatis is necessary, since up to 80 percent of infections in women are asymptomatic. Due to medical, psychosocial and legal reasons, laboratory diagnosis of STI has to be certain. This offers a great challenge to laboratories. Since etiological agents are susceptible to environmental conditions, present a high adaptation to their human host and have particular physiological characteristics, their laboratory diagnosis is more difficult than diagnosis of conventional microorganisms. Otherwise, the diagnostic techniques currently available for non-viral STI are characterized by their excellent sensitivity and specificity, which result of great interest given the curable nature of these infections. Clinical specimens obtained for diagnosis of STI and other genital infections, such as bacterial vaginosis or Candidiasis represent a large proportion of specimens processed by clinical laboratories. Thus, the creation of norms and quality control guidelines for laboratories which diagnose these infections, and also the epidemiologic and genetic surveillance of circulating sex transmitted microorganisms should be considered a priority in our country. The objective of this study is to review current literature on accurate diagnostic procedures especially for three non-viral STI agents: C. trachomatis, N. gonorrhoeae, and Trichomonas vaginalis.

Lung structure and function of infants with recurrent wheeze when asymptomatic.

Infants with recurrent wheeze have repeated episodes of airways obstruction; however, relatively little is known about the structure and function of their lungs when not symptomatic. The current authors evaluated whether infants with recurrent wheeze have smaller airway lumens or thickened airway walls, as well as decreased airway function. High-resolution computed tomography images 1 mm thick were obtained at three anatomic locations at an elevated lung volume and at functional residual capacity. Forced expiratory flows were also measured in subjects with recurrent wheeze. Airway lumen, wall areas and lung tissue density were not significantly different for recurrent wheeze (n = 17) and control (n = 14) subjects; however, subjects with recurrent wheeze had lower forced expiratory flows than predicted. Similar findings were obtained when subjects were grouped by exposure to tobacco smoke. These findings indicate that infants with recurrent wheeze, as well as exposure to tobacco smoke, have lower airway function when not symptomatic. The lower forced expiratory flows may result from a degree of airway narrowing that could not be resolved with the methodology employed or from other mechanisms, such as more collapsible airways or decreased pulmonary elastic recoil.

[Molecular characterization of Chilean isolates of streptococcus agalactiae]. / Caracterización molecular en aislados chilenos de Streptococcus agalactiae.

BACKGROUND: Streptococcus agalactiae is the main causing organism of invasive infections such as sepsis and meningitis in the newborn. AIM: To perform a genotype characterization of Streptococcus agalactiae strains coming form invasive infections of newborns and colonized pregnant women. MATERIAL AND METHODS: A group of 58 strains not related epidemiologically isolated from colonized pregnant women and invasive infections in newborns, were studied. Pulsed field electrophoresis (PFGE) and polymerase chain reaction amplification of hylB and IS 1,548 genes, as possible virulence markers, were performed. RESULTS: Among the studied strains, 37 genetic subtypes were observed. There were nine groups of identical PFGE patterns. Three corresponded to serotype la and six to serotype III. An erythromycin and clindamycin resistant clone was identified in three colonized women and a newborn with sepsis, which were not epidemiologically related. The hylB gene was equally present in cases of neonatal meningitis or colonized pregnant women. CONCLUSIONS: There was a great degree of polymorphism among the studied strains. The ample presence of hylB gene and the absence of the insertion element IS1548 in the hylB gene in invasive and colonizing strains, indicates that both groups of strains are potentially pathogenic.

Caracterización molecular en aislados chilenos de Streptococcus agalactiae / Molecular characterization of Chilean isolates of streptococcus agalactiae

Streptococcus agalactiae is the main causing organism of invasive infections such as sepsis and meningitis in the newborn. Aim: To perform a genotype characterization of Streptococcus agalactiae strains coming form invasive infections of newborns and colonized pregnant women. Material and methods: A group of 58 strains not related epidemiologically isolated from colonized pregnant women and invasive infections in newborns, were studied. Pulsed field electrophoresis (PFGE) and polymerase chain reaction amplification of hylB and IS 1548 genes, as possible virulence markers, were performed. Results: Among the studied strains, 37 genetic subtypes were observed. There were nine groups of identical PFGE patterns. Three corresponded to serotype la and six to serotype III. An erythromycin and clindamycin resistant clone was identified in three colonized women and a newborn with sepsis, which were not epidemiologically related. The hylB gene was equally present in cases of neonatal meningitis or colonized pregnant women. Conclusions: There was a great degree of polymorphism among the studied strains. The ample presence of hylB gene and the absence of the insertion element IS1548 in the hylB gene in invasive and colonizing strains, indicates that both groups of strains are potentially pathogenic.

Resultado neonatal adverso en la rotura prematura de membranas de pretérmino según el modo del parto / Adverse neonatal outcome in patients with preterm PROM according to mode of delivery

Objetivo: Evaluar el resultado neonatal adverso según modo de parto en la rotura prematura de membranas de pretérmino (RPMPT). Métodos: Participaron 135 embarazadas entre 24 y 34 semanas de gestación con diagnóstico de rotura prematura de membranas. Se excluyeron pacientes en trabajo de parto y condiciones maternas y fetales severas que pudiesen alterar el resultado perinatal. Todas las embarazadas tuvieron evaluación microbiológica del líquido amniótico y cérvicovaginal, y recibieron antibióticos, corticoesteroides y manejo expectante hasta las 35 semanas. Se definió resultado neonatal adverso (RA) compuesto, la variable que incluyó morbilidad neonatal severa, secuelas o muerte neonatal. Se definió invasión microbiana de la cavidad amniótica (IMCA) por cultivo positivo del líquido amniótico. Funisitis se diagnosticó por la presencia de leucocitos polimorfonucleares en la pared de los vasos umbilicales o gelatina de Warthon. La cesárea se realizó por indicaciones obstétricas o por urgencias. Para el análisis se usó curva ROC y chi cuadrado. Resultados: Se incluyeron 116 pacientes. Modo del parto: vaginal 50,1 por ciento y cesárea 49,9 por ciento. La IMCA fue 52,6 por ciento y el RA 17,2 por ciento. El RA no dependió del modo del parto (vaginal 13,6 por ciento vs. cesárea 21,1 por ciento). La vía del parto no influyó en el RA de los subgrupos donde este resultado fue más frecuente: <1500 gramos de peso al nacer (vaginal 46,7 por ciento vs cesárea 47,4 por ciento) y <31 semanas de gestación al parto (vaginal 35 por ciento vs cesárea 35,5 por ciento). El RA se asoció con variables infecciosas: IMCA 24,6 por ciento, IMCA por S agalactiae 71,4 por ciento, corioamnionitis histológica 100 por ciento y funisitis 94,4 por ciento. Las 30 semanas de edad gestacional (Curva Roe) identificó al feto con mayor riesgo de resultado neonatal adverso según edad gestacional al parto. Conclusión: En la paciente con RPMPT manejada con antibióticos, corticosteroides y conducta expe...

Aplicación de método molecular en la detección de Mycoplasma genitalium en hombres y en mujeres embarazadas / Molecular detection of Mycoplasma genitalium in men and pregnant women

Mycoplasma genitalium es un patógeno oportunista del tracto genital. En el hombre es causa de uretritis, en tanto que en mujeres ha sido implicado en la etiología de cervicitis y de enfermedad inflamatoria pelviana (EIP). El objetivo de este estudio fue determinar la prevalencia de M. genitalium en pacientes masculinos con uretritis y en muestras vaginales de mujeres embarazadas. Se obtuvo muestras de secreción uretral en 37 pacientes con uretritis y de muestras vaginales de 50 consecutivas mujeres embarazadas, determinándose la presencia de M. genitalium mediante reacción de polimerasa en cadena (RPC). Las muestras de secreción uretral fueron también evaluadas en busca de Chlamydia trachomatis, Neisseria gonorrhoeae y Ureaplasma sp en tanto que en las de origen vaginal se investigó la microbiota y presencia de micoplasmas de tipo genital. Veintitrés casos fueron clasificados como uretritis no gonocóccica (UNG) y 14 como enfermedad gonocóccica. M. genitalium fue detectado en 3 de 23 (13,04 por ciento) varones con UNG; en dos casos asociado a Ureaplasma sp, y en un paciente como agente único. C. trachomatis fue detectado en 7 pacientes con UNG y en uno con gonorrea. Ureaplasma sp fue aislado en 13 (35,1 por ciento) pacientes, 8 casos de UNG y en 5 con gonorrea. El microorganismo fue detectado también en 6 (15 por ciento) de 40 mujeres; en 5 casos en presencia de microbiota normal (score de Nugent 0-3), y en un caso en presencia de vaginosis bacteriana. Ureaplasma spp fue aislado en las seis muestras positivas. En conclusión, este estudio demuestra que M. genitalium debe ser también considerado en la etiología de la UNG así como en el tracto genital inferior en la mujer embarazada, en presencia de una microbiota vaginal normal.

[Molecular detection of Mycoplasma genitalium in men and pregnant women]. / Aplicación de método molecular en la detección de Mycoplasma genitalium en hombres y en mujeres embarazadas.

Mycoplasma genitalium is an opportunistic pathogen of the genital tract. It has been implicated as an etiological agent of urethritis in men and cervicitis and pelvic inflammatory disease (PID) in women. The aim of this study was to determine the prevalence of Mycoplasma genitalium in male urethritis and in vaginal specimens of pregnant women. Urethral specimens obtained from 37 men presenting with urethritis and vaginal specimens from 50 consecutive pregnant women were tested for the presence of M. genitalium by polymerase chain reaction (PCR). The urethral specimens were also examined for the presence of Neisseria gonorrhoeae, Chlamydia trachomatis and Ureaplasma sp whereas the vaginal microbiota and the presence of genital mycoplasma were investigated in the vaginal specimens. Twenty three cases were classified as nongonococcal urethritis (NGU) and 14 as gonorrheal disease. M. genitalium was detected in 3 of 23 (13.04%) men with NGU; in two cases with Ureaplasma sp, and in one patient as the unique agent. C. trachomatis was found in 7 patients with NGU and in one patient with gonorrhea. Ureaplasma sp was isolated in 13 (35.1%) patients, 8 cases of NGU and in 5 patients with gonorrhea. The organism was also detected in 6 (15%) of 40 women; in 5 cases in the presence of a normal microbiota (Nugent score 0-3), and an in one case in the presence of bacterial vaginosis. Ureaplasma spp was isolated in the 6 positive specimens. This study indicates that M. genitalium can be detected in urethral specimens of some cases of NGU as well as in the lower genital tract of pregnant women in the presence of a normal vaginal microbiota.

Portación faríngea de Mycoplasma pneumoniae en niños chilenos / Asymptomatic pharyngeal carriage of Mycoplasma pneumoniae in Chilean children

La reacción de polimerasa en cadena (RPC) ha demostrado ser una alternativa sensible para el diagnóstico de enfermedad por M. pneumoniae proporcionando resultados en forma oportuna. Sin embargo, no se conoce bien la frecuencia de portación o la persistencia de este microorganismo en la faringe luego de una enfermedad respiratoria en niños, factores que podrían limitar la utilidad de este procedimiento de diagnóstico. Con el objeto de conocer la frecuencia de portación silenciosa de M. pneumoniae en niños, se estudiaron mediante RPC muestras faríngeas de 185 niños sin signos ni síntomas de infección respiratoria, enrolados en dos consultorios de la Región Metropolitana, Chile, entre septiembre de 2002 y agosto de 2003. M. pneumoniae fue detectado en 4 (2,16%) niños. Las muestras positivas podrían representar portación o persistencia post enfermedad de M. pneumoniae.

Utilidad de la reacción de polimerasa en cadena para la detección de Mycoplasma pneumoniae en adultos mayores con neumonía adquirida en la comunidad / Diagnostic utility of the polymerase chain reaction for the diagnosis of Mycoplasma pneumoniae in elderly patients with community-acquired pneumonia

Mycoplasma pneumoniae es una causa frecuente de neumonía adquirida en la comunidad (NAC) en niños y adultos jóvenes, existiendo escasa información de su frecuencia en el adulto mayor. Se analizó la reacción de polimerasa en cadena (RPC) con dos pares de partidores, gen de la adhesina P1 y gen 16S rRNA, para la detección de M. pneumoniae en lavado faríngeo de 84 pacientes de 60-96 años con diagnóstico clínico de NAC, desde septiembre de 2002 hasta agosto de 2004. Los resultados de la RPC fueron comparados con los de la serología mediante inmunofluorescencia indirecta (IFI). Se detectó infección por M. pneumoniae mediante serología o RPC en 11 de 84 pacientes (13,1%). La serología fue positiva en 8 (72,7%) y la RPC en 7 (63,6%) muestras. La serología en la muestra de suero en fase aguda fue positiva en 5 de 11 pacientes (45,4%), en 4 de ellos por la presencia de IgM. En 4 pacientes con serología positiva la RPC fue negativa. En 3 pacientes con serología negativa la RPC fue positiva. Las dos RPC mostraron 100% de correlación y la sensibilidad fue la misma; no se detectaron muestras con efecto inhibitorio de la reacción. En conclusión, M. pneumoniae debería ser considerado en la etiología de la NAC en adultos mayores. La detección de este microorganismo debe basarse en el uso combinado de serología y RPC.

[Asymptomatic pharyngeal carriage of Mycoplasma pneumoniae in Chilean children]. / Portación faríngea de Mycoplasma pneumoniae en niños chilenos.

PCR has become a sensitive option for the rapid detection of Mycoplasma pneumoniae in respiratory specimens, but little is known of the frequency of its asymptomatic carriage or persistence in the throat after Mycoplasma disease in healthy children. To investigate the frequency of asymptomatic carriage of M. pneumoniae in children, we studied by PCR throat specimens from 185 respiratory asymptomatic children aged 1-14 years, enrolled at two pediatric ambulatory health services of Santiago, Chile from September 2002 through August 2003. M. pneumoniae DNA was detected in 4 (2.16%) children. Positive specimens could represent either asymptomatic carriage or persistence of the organism from a previous disease.

[Diagnostic utility of the polymerase chain reaction for the diagnosis of Mycoplasma pneumoniae in elderly patients with community-acquired pneumonia]. / Utilidad de la reacción de polimerasa en cadena para la detección de Mycoplasma pneumoniae en adultos mayores con neumonía adquirida en la comunidad.

Mycoplasma pneumoniae is a common cause of community-acquired pneumonia (CAP) in children and young adults, but limited information about its prevalence in the elderly is available. The polymerase chain reaction (PCR) with primers targeting the cytadhesine P1 gene and the 16S rRNA gene was analyzed for detecting M. pneumoniae in throat washings of 84 patients, aged 60-96 years, with clinical diagnosis of CAP, from September 2002 through August 2004, in Santiago, Chile. PCR results were compared with serology performed by indirect immunofluorescence (IFI). Specimens from 11 of 84 patients (13.1%) were positive for M. pneumoniae by any test. The IFI test was positive in 8 (72.7%) patients and PCR in 7 (63.6%) cases. The acute phase sera allowed diagnosis of M. pneumoniae in 5 of 11 patients (45.4%), 4 of them showing an IgM response. PCR was negative in 4 patients with positive serology and 3 patients were positive only by PCR. The two PCR primers showed 100% correlation, and a similar sensitivity; no inhibitory specimens for PCR were detected. In conclusion, M. pneumoniae should be considered as a potential etiologic agent of CAP in the elderly. Its detection must be performed by a combination of PCR and serology.