Detección molecular de patógenos en deposiciones en niños consultantes por diarrea aguda en Servicios de Urgencia

Introducción: La diarrea aguda continúa siendo una de las principales causas de morbilidad en niños; sin embargo, el diagnóstico etiológico presenta limitaciones dada la baja sensibilidad de los métodos tradicionales. Objetivo: Describir los microorganismos identificados en niños que acudieron al Servicio de Urgencia (SU) de un hospital universitario en Santiago, Chile, por diarrea aguda y a los que se le solicitó panel molecular gastrointestinal. Métodos: Se revisaron fichas clínicas y resultados de panel gastrointestinal realizados entre junio de 2017 y marzo de 2020. Resultados: Se incluyeron 198 pacientes, edad promedio de 54,5 meses y 60,6% (120/198) de sexo masculino. La positividad del panel fue de 78,8% (156/198) con 35,3% (55/156) de las muestras polimicrobianas. Se identificaron 229 microorganismos, de los cuales 72,9% (167/229) corresponden a bacterias, 25,8% (59/229) a virus y 1,3% (3/229) a parásitos. Destacaron Campylobacter spp. y Escherichia coli enteropatógena (ECEP) como las bacterias más frecuentemente identificadas. Los pacientes con detección de Campylobacter spp. presentaron con mayor frecuencia fiebre (p = 0,00). ECEP se aisló principalmente (82,5%) en muestras polimicrobianas. Discusión: Los resultados enfatizan el potencial que poseen los estudios moleculares para mejorar el diagnóstico etiológico de la diarrea, pero a la vez llevan a cuestionar el rol patogénico de algunos microorganismos identificados.

Background: Acute diarrhea continues to be one of the main causes of morbidity in children, however the etiologica diagnosis presents limitations given the low sensitivity of traditional methods. Aim: To describe the microorganisms identified in children who attended the emergency department (ED) in Santiago, Chile, due to acute diarrhea and to whom a gastrointestinal panel was requested as part of their study. Material and Methods: Clinical records and results of the gastrointestinal panel carried out between June 2017 and March 2020 were reviewed. Results: 198 patients were included, the average age was 54.5 months and 60.6% (120/198) were males. Positivity was 78.8% (156/198) with 35.3% (55/156) of the samples being polymicrobial. 229 microorganisms were identified, of which 72.9% (167/229) corresponded to bacteria, 25.8% (59/229) to viruses, and 1.3% (3/229) to parasites. Campylobacter spp. and enteropathogenic Escherichia coli (EPEC) were the most frequently identified bacteria. Patients with detection of Campylobacter spp. presented a higher frequency of fever (p = 0.00). EPEC was isolated in 82.5% of the cases in polymicrobial samples. Discussion: The results emphasize the potential of molecular studies to improve the etiological diagnosis of diarrhea and at the same time lead to question the pathogenic role of some microorganisms.

Phylogeographic relationships and morphological evolution between cave and surface Astyanax mexicanus populations (De Filippi 1853) (Actinopterygii, Characidae).

The Astyanax mexicanus complex includes two different morphs, a surface- and a cave-adapted ecotype, found at three mountain ranges in Northeastern Mexico: Sierra de El Abra, Sierra de Guatemala and Sierra de la Colmena (Micos). Since their discovery, multiple studies have attempted to characterize the timing and the number of events that gave rise to the evolution of these cave-adapted ecotypes. Here, using RADseq and genome-wide sequencing, we assessed the phylogenetic relationships, genetic structure and gene flow events between the cave and surface Astyanax mexicanus populations, to estimate the tempo and mode of evolution of the cave-adapted ecotypes. We also evaluated the body shape evolution across different cave lineages using geometric morphometrics to examine the role of phylogenetic signal versus environmental pressures. We found strong evidence of parallel evolution of cave-adapted ecotypes derived from two separate lineages of surface fish and hypothesize that there may be up to four independent invasions of caves from surface fish. Moreover, a strong congruence between the genetic structure and geographic distribution was observed across the cave populations, with the Sierra de Guatemala the region exhibiting most genetic drift among the cave populations analysed. Interestingly, we found no evidence of phylogenetic signal in body shape evolution, but we found support for parallel evolution in body shape across independent cave lineages, with cavefish from the Sierra de El Abra reflecting the most divergent morphology relative to surface and other cavefish populations.

Morphological description of gametes in cave and surface populations of Astyanax mexicanus (De Filippi, 1853).

The Mexican tetra Astyanax mexicanus presents two contrasting morphs, a widely distributed surface morph and a cave-adapted morph. These cave-adapted morphs have evolved independently from two different lineages (i.e. 'old' and 'new' lineages); therefore, this model system gives a unique opportunity to explore parallel adaptive evolution in biological traits. The present study corresponds to the first morphological description of the Astyanax mexicanus maturation process of the spermatozoa and oocytes, using thermal and hormonal stimuli to promote spermatogenesis and oogenesis, considering surface and cave morphs from both lineages. We corroborate the relevance of thermal and hormonal stimuli to promote gamete maturation. The hormone Ovaprim (GnRHa + Domperidone) is an effective promoter of ovarian development, maturation end in oocytes and spawning in Astyanax mexicanus. The sperm morphology of Astyanax mexicanus includes the sperm head, the midpiece, and tail or flagellum. We found differences in the spermatozoan total length between environments (F = 9.929, P = 0.05) and linages (F = 49.86, P = 0.005). The oocytes showed a spherical conformation with a mean diameter of 822.4 ± 194.1 µm for the surface populations, and 604.6 ± 38.3 µm for the cave populations. The oocyte chorion presents ridges and grooves that are arranged radially towards the micropyle. A plug in the micropyle zone was observed after fertilization, confirmed by the outer membrane of the chorion, which provides some weak adhesiveness to the substrate. We observed differences in chorion thickness between the contrasting environmental conditions. This is the first morphological characterization of the Sótanos Vázquez, Escondido and Tigre, which previous to this study were only known from speleological expeditions, with no previous biological information available.

A geographical cline in craniofacial morphology across populations of Mesoamerican lake-dwelling fishes.

Together, the complex geological history and climatic diversity of Mesoamerica create a rich source of biodiversity from which evolutionary processes can be studied. Here, we discuss highly divergent morphs of lake-dwelling fishes distributed across Mexico and Central America, originally recognized as members of different genera (Astyanax and "Bramocharax"). Recent phylogenetic studies, however, suggest these morphs group within the same genus and readily hybridize. Despite genetic similarities, Bramocharax morphs exhibit stark differences in cranial shape and dentition. We investigated the evolution of several cranial traits that vary across morphs collected from four lakes in Mexico and Nicaragua and discovered an ecomorphological cline from northern to southern lakes. Northern populations of sympatric morphs exhibit a similar cranial shape and tooth morphology. Southern populations of Bramocharax morphs, however, showed a larger disparity in maxillary teeth, length and frequency of unicuspid teeth, an elongated snout, and a streamlined cranium compared to Astyanax morphs. This divergence of craniofacial morphology likely evolved in association with differences in trophic niches. We discuss the morphological differences across the four lake systems in terms of geological history and trophic dynamics. In summary, our study suggests that Bramocharax morphs are likely locally adapted members derived from independent Astyanax lineages, highlighting an interesting parallel evolutionary pattern within the Astyanax genus.

Caracterización clínica y molecular de bacteriemias causadas por enterobacterias productoras de β -lactamasas de espectro extendido: 2004-2007 / Clinical and molecular characterization of ESBL-producing enterobacteria isolated from bacteremia in a university hospital

Introduction: Extended-spectrum-β-lactamases (ESBL) are plasmid-encoded enzymes that confer resistance to multiple antimicrobials. ESBL-producing enterobacteria that cause bacteremia limit therapeutic options and increase mortality. Objective: To perform a clinical and molecular description of bacteremia caused by ESBL-producing enterobacteria. Method: We retrospectively studied the cases of bacteremia due to ESBL-producing Escherichia coli, Klebsiella pneumoniae and Proteus spp in adults admitted to a university hospital during the years 2004-2007. We reviewed the clinical records and antimicrobial susceptibility patterns. Molecular typing was performed by polymerase chain reaction and study of clonality by pulsed-field electrophoresis. Results: We found a prevalence of 9.8 percent ESBL in enterobacteria causing bacteremia. Decreased susceptibility to quinolones and aminoglycosides was observed, without resistance to carbapenems. The predominant ESBL types were CTX-M (96 percent), TEM (62 percent) and GES (28 percent). 79 percent of the strains presented more than one type of ESBL. Clinical analysis revealed high prevalence of risk factors, previous use of antimicrobials and of invasive devices. There was no significant clonality. Conclusion: The presence of ESBLs in bloodstream infections is a clinical problem that must be considered when choosing empiric therapy.

Introducción: β-lactamasas de espectro extendido (BLEE) son enzimas plasmidiales que confieren resistencia a múltiples antimicrobianos. Las bacteriemias por enterobacterias productoras de BLEE restringen las opciones terapéuticas y aumentan la mortalidad. Objetivo: Realizar una descripción clínica y molecular de las bacteriemias causadas por enterobacterias productoras de BLEE. Método: Se estudiaron retrospectivamente los casos de bacteriemia por Escherichia coli, Klebsiella pneumoniae y Proteus spp. confirmadas para BLEE, en adultos ingresados en un hospital universitario durante los años 2004-2007. Se revisaron los registros clínicos y de susceptibilidad. Se realizó tipificación molecular por reacción de polimerasa en cadena y estudio de clonalidad por electroforesis de campo pulsado. Resultados: Se identificó una prevalencia de BLEE de 9,8 por ciento en enterobacterias causantes de bacteriemias. Se observó susceptibilidad disminuida a quinolonas y aminoglucósidos, sin resistencia a carbapenémicos. Los tipos de BLEE predominantes fueron CTX-M (96 por ciento), TEM (62 por ciento) y GES (28 por ciento). El 79 por ciento de las cepas presentó más de un tipo de BLEE. El análisis clínico reveló alta frecuencia de patologías de riesgo, uso previo de antimicrobianos y uso de dispositivos invasores. No se encontró clonalidad significativa. Conclusión: La presencia de BLEE en bacteriemias constituye un problema clínico que debe ser considerado al elegir la terapia empírica.

Diagnóstico de la infección por Treponema pallidum en pacientes con sífilis temprana y neurosífilis mediante reacción de la polimerasa en cadena / Laboratory diagnosis of Treponema pallidum infection in patients with early syphilis and neurosyphilis through a PCR-based test

Syphilis is a sexually transmitted disease caused by Treponema pallidum. The diagnosis is based mainly in clinical presentation and non-specific assays. PCR-based diagnosis has been suggested as an attractive alternative method. The aim of this study was the validation of a PCR-based test for the diagnosis of early syphilis (ES) and neurosyphilis (NS). Clinical samples of mucocutaneous lesions and cerebrospinal fluid (CSF) specimens from patients previously diagnosed for ES and NS respectively using an enlarged gold standard, were tested by PCR. The reaction was done using primers targeting the tpN47gene. Twenty out of 21 mucocutaneous samples from patients diagnosed with ES were positive by PCR, with a clinical sensitivity of 95 percent. Four out of 8 CSF samples from patients previously diagnosed with NS were positive by PCR, with a clinical sensitivity of 50 percent. The clinical specificity for both ES and NS was 100 percent. The PCR sensitivity and specificity for mucocutaneous samples allowed us to implement this assay in our laboratory for routine diagnosis. Although the sensitivity of the PCR in CSF was low, it may be useful to support clinical diagnosis.

La sífilis es una enfermedad de transmisión sexual producida por Treponema pallidum, cuyo diagnóstico se realiza presuntivamente basándose en aspectos clínicos y análisis de especificidad limitada. La reacción de la polimerasa en cadena (RPC) ha sido planteada como una alternativa diagnóstica de mayor sensibilidad y especificidad. El objetivo de este trabajo fue validar una RPC para el diagnóstico de sífilis temprana (ST) y neurosífilis (NS). Se utilizaron muestras de lesiones muco-cutáneas y de LCR de pacientes con sospecha de cursar ST y NS respectivamente, previamente diagnosticados, utilizando un estándar de oro ampliado. La RPC fue realizada con partidores dirigidos al gen tpN47. De las 21 muestras de pacientes con ST, la RPC resultó positiva en 20, lo que resulta en una sensibilidad clínica de 95 por ciento. De las 8 muestras de pacientes con NS, la RPC resultó positiva en 4, obteniéndose una sensibilidad clínica de 50 por ciento. La especificidad clínica para ST y NS fue de 100 por ciento. La excelente sensibilidad y especificidad de la RPC para muestras muco-cutáneas permitió la exitosa implementación de este análisis en nuestro laboratorio para el diagnóstico de rutina. Si bien la sensibilidad de la RPC en LCR es baja, es muy útil para apoyar el diagnóstico clínico.

Aumento de resistencia de Streptococcus agalactiae vaginal-anal en el tercer trimestre de gestación a eritromicina y clindamicina al cabo de una década de tamizaje universal / Streptococcus agalactiae increase in resistance to erythromycin and clindamycin in vaginal-anal colonization in third quarter of pregnancy in one decade of universal screening

Introduction: Streptococcus agalactiae (GBS) is the main causative agent of early perinatal sepsis. The acquisition of prevention policies has led to frequent use of intrapartum antibiotics. Surveillance of antimicrobial resistance is indispensable for defining drugs of choice and alternatives for such prophylaxis. Objectives: To determine the evolution of antimicrobial resistance of GBS from maternal colonization to drugs used in the prevention of neonatal sepsis, between 2002 and 2008. Methods: We studied 100 GBS positive vaginal and anal samples from pregnant women. Disc diffussion susceptibility method was performed for penicillin, ampicillin, cefazolin, erythromycin and clindamycin according to the Clinical and Laboratory Standards Institute (CLSI). Results: We analyzed the susceptibility of 99 strains. Seventeen were resistant to erythromycin (17.1 percent) and 13 were resistant to clindamycin (13.1 percent). Thirteen of the 17 strains resistant to erythromycin had the MLS phenotype (resistance to erythromycin and clindamycin) and 4 had the M phenotype (resistance to erythromycin only). Within the MLS phenotype, resistance was constitutive in 9 strains, and induced in 4 strains (positive D test). Compared with 2002 there was a significant increase in resistance to clindamycin (from 3.27 percent to 13.1 percent p < 0.002) and erythromycin (1.09 percent to 17 percent p < 0.001). 100 percent GSB remained sensitive to penicillin and ampicillin. Conclusions: GBS remains highly susceptible to drugs of choice for prevention of perinatal sepsis. There is a significant increase in antimicrobial resistance to clindamycin and erythromycin. Therefore, it is necessary to request susceptibility testing in GBS from third trimester of pregnancy screening in patients allergic to penicillin.

Introducción: Streptococcus agalactiae es el principal agente causal de sepsis perinatal precoz. La adquisición de políticas de prevención ha traído consigo la utilización frecuente de antimicrobianos intra-parto. La vigilancia de resistencia antimicrobiana se hace indispensable para definir el fármaco de elección y alternativas en dicha profilaxis. Nuestro centro realiza tamizaje universal desde hace 10 años. Objetivos: Determinar la evolución de la resistencia antimicrobiana de S. agalactiae de colonización materna, a los antimicrobianos utilizados en la prevención de sepsis neonatal, entre 2002 y 2008. Métodos: Se estudiaron 100 muestras vaginales-anales positivas para S. agalactiae de mujeres embarazadas, con edad gestacional de 35 a 37 semanas. Se realizó estudio de susceptibilidad in vitro por discos a penicilina, ampicilina, cefazolina, eritromicina y clindamicina, según método estandarizado por Clinical and Laboratory Standards Institute (CLSI). Resultados: Se analiza la susceptibilidad de 99 cepas. Diecisiete fueron resistentes a eritromicina (17,1 por ciento) y 13 eran resistentes a clindamicina (13,1 por ciento). De las 17 cepas resistentes a eritromicina, 13 eran fenotipo MLS y 4 del fenotipo M. Dentro del fenotipo MLS, la resistencia fue constitutiva en nueve cepas e inducible en cuatro cepas (test D positivo). En comparación con el año 2002, hubo un aumento significativo de resistencia a clindamicina (de 3,2 a 13,1 por ciento p < 0,002) y a eritromicina (de 1,09 a 17 por ciento p < 0,001). Streptococcus agalactiae se mantuvo 100 por ciento sensible a penicilina y ampicilina. Conclusiones: S. agalactiae mantiene alta sensibilidad a los antimicrobianos de elección para la prevención de sepsis neonatal y a un antimicrobiano alternativo: cefazolina. Se observó un aumento significativo de resistencia antimicrobiana a clindamicina y eritromicina. Se hace necesario, entonces, solicitar antibiograma en el tamizaje del tercer trimestre del embarazo, en pacientes alérgicas a penicilina.

Etiología de la neumonía en pacientes chilenos infectados por el virus de la inmunodeficiencia humana / Etiology of pneumonia in Chilean HIV-infected adult patients

Objectives: To establish the etiology of pneumonia and to compare the yield of diagnostic techniques for diagnosis of Pneumocystis jiroveci and Mycobacterium tuberculosis infections in HIV-1-infected patients. Patients and Methods: Subjects underwent sputum induction and bronchoalveolar lavage (BAL). Gram, Ziehl-Neelsen, silver stain (SS) and immunofluorescense staining (IF) for P. jiroveci, fluorescent stain for mycobacteria, PCR for P. jiroveci andM. tuberculosis, aerobic, fungal and mycobacterial cultures, respiratory viruses and CMV cultures were performed on the sputum and BAL. IgM for Mycoplasma pneumoniae and Chlamydophyla pneumoniae, and Legionella pneumophila urinary antigen were also obtained. Results: Sixty patients were included. An etiologic diagnosis was made in 97 percent. Pneumocystisjiroveci was the most frequent etiology (58 percent) followed by Streptococcus pneumoniae (12 percent), and Mycobacterium avium complex (12 percent). Mycobacterium tuberculosis was found in 5 percent. Conclusions: The comparison of diagnostic methods for P. jiroveci showed a higher sensitivity of IF and SS in BAL than in sputum, however PCR was equally sensitive in both samples. With this approach a precise etiologic diagnosis was reached in the great majority of patients. The most common etiology was P. jiroveci. IF in BAL remains the gold standard for diagnosis of P. jiroveci pneumonia.

Objetivos: Establecer la etiología de la neumonía y comparar el rendimiento de diferentes técnicas para el diagnóstico de las infecciones por Pneumocystis jiroveci y Mycobacterium tuberculosis en pacientes con infección por virus de inmunodeficiencia humana (VIH). Material y Métodos: De cada paciente se obtuvo esputo inducido y se efectuó LBA. A las muestras obtenidas se les realizó tinciones de Gram, Ziehl-Neelsen, plata e inmunofluores-cencia (IF) para P. jiroveci y M. tuberculosis; reacción de polimerasa en cadena (RPC) para ambos microorganismos; cultivos aeróbicos, fúngicos, para micobacterias, virus respiratorios y citomegalovirus. También se realizó determinación de IgM de Mycoplasma pneumoniae y Chlamydophyla pneumoniae y antígeno urinario de Legionella pneumophila. Resultados: Se incluyeron 60 pacientes, lográndose diagnóstico etiológico en 97 por ciento de los casos. Pneumocystis jiroveci fue la etiología más frecuente (58 por ciento), seguida por Streptococcus pneumoniae (12 por ciento) y Mycobacterium avium complex (MAC) (12 por ciento). Mycobacterium tuberculosis fue encontrado en 5 por ciento. Conclusiones: La comparación de los métodos diagnósticos para P. jiroveci mostró una mayor sensibilidad de la IF y tinción de plata en LBA que en esputo; sin embargo, la RPC fue igualmente sensible en ambos tipos de muestras. Con esta estrategia se logró establecer etiología en la gran mayoría de los pacientes. La etiología más común fue P. jiroveci. IF en LBA sigue siendo el estándar para el diagnóstico de la neumonía por P. jiroveci.

[Clinical and molecular characterization of ESBL-producing enterobacteria isolated from bacteremia in a university hospital]. / Caracterización clínica y molecular de bacteriemias causadas por enterobacterias productoras de β -lactamasas de espectro extendido: 2004-2007.

INTRODUCTION: Extended-spectrum-ß-lactamases (ESBL) are plasmid-encoded enzymes that confer resistance to multiple antimicrobials. ESBL-producing enterobacteria that cause bacteremia limit therapeutic options and increase mortality. OBJECTIVE: To perform a clinical and molecular description of bacteremia caused by ESBL-producing enterobacteria. METHOD: We retrospectively studied the cases of bacteremia due to ESBL-producing Escherichia coli, Klebsiella pneumoniae and Proteus spp in adults admitted to a university hospital during the years 2004-2007. We reviewed the clinical records and antimicrobial susceptibility patterns. Molecular typing was performed by polymerase chain reaction and study of clonality by pulsed-field electrophoresis. RESULTS: We found a prevalence of 9.8% ESBL in enterobacteria causing bacteremia. Decreased susceptibility to quinolones and aminoglycosides was observed, without resistance to carbapenems. The predominant ESBL types were CTX-M (96%), TEM (62%) and GES (28%). 79% of the strains presented more than one type of ESBL. Clinical analysis revealed high prevalence of risk factors, previous use of antimicrobials and of invasive devices. There was no significant clonality. CONCLUSION: The presence of ESBLs in bloodstream infections is a clinical problem that must be considered when choosing empiric therapy.

[Description of assessment processes at the Medical School of the Pontificia Universidad Católica de Chile: a ten year experience]. / Descripción de los Procesos de Evaluación en la Escuela de Medicina de la Pontificia Universidad Católica de Chile: Experiencia de 10 años.

Globalization of health care seems to be irreversible and beyond cultural differences and local realities; consequently, medical education needs to have a common set of core principles or standards that may be applied worldwide. The aim of participating in assessment processes is to guarantee that medical education takes place in a sufficiently rich environment to promote extensive academic purposes. The Medical School of the Pontificia Universidad Católica de Chile (PUC) participated in three assessment processes that included three stages: internal assessment, external assessment, and accreditation judgment. Two of these assessments were voluntarily carried out following the standards set by the Liaison Committee on Medical Education-LCME, and they took place in 1997 and 2007. The other assessment was based on standards set by the Chilean accrediting organism, the National Committee for Undergraduate Program Accreditation (Comité Nacional de Acreditación de Pregrado-CNAP) and took place in the year 2001. In all three experiences, internal assessment was the most enriching stage, stimulating refections among students and teachers in order to recognize areas of strengths and weaknesses. External assessment processes, especially those based on international standards, are very important for the institutional and program development of Medical Schools. The PUC Medical School on its whole learnt how to carry out an assessment process and was able to improve several weaknesses without pressure, moving from quality assurance to quality enhancement. The present paper analyzes the major challenges involved in an external assessment process.

Evaluación de un test comercial de avidez de IgG: Aporte al diagnóstico de primoinfección por Toxoplasma gondii / Evaluation of an IgG avidity commercial test: Contribution to diagnosis of primary infection caused by Toxoplasma gondii

Introduction: Toxoplasmosis (T) is a major chronic parasitic infection in immunocompromised patients and pregnant women. It is important to discriminate between acute phase (AT) and chronic phase (CT). Diagnosis is serological in immunocompetent patients (concentration of IgG and IgM). Objective: To evaluate the utility of an IgG avidity test (A-IgG) to identify the acute and chronic stage. Avidity is the strength of affinity between a specific immunoglobulin and the protein antigenic epitope of the infecting agent, an affinity that increases over time. Patients and Methods: We used a qualitative kit that measures the avidity of IgG, discriminating the two phases. In 35 patients with clinical diagnosis of AT and/or CT, IgG, IgM and IgG A (VIDAS®) were performed. Results: Patients with AT were positive for IgM and IgG, but presented weak avidity. In the 21 cases with CT, 52 percent (n: 11) were IgM positive and 100 percent (n: 21) had positive IgG with strong avidity. Discussion: The results confirm that the test of A-IgG may be useful in the diagnosis of AT, and has 100 percent concordance with reference test (qualitative IgM + quantitative IgG). The result is available within 24 hrs, and may be useful in diagnosis of AT in pregnant women.

Introducción: Toxoplasmosis (T) es una infección parasitaria crónica importante en pacientes inmunocompro-metidos y mujeres embarazadas. Es relevante discriminar entre fase aguda (TA) y fase crónica (TC). Su diagnóstico es serológico en inmunocompetentes (detección de IgG e IgM). Objetivo: Evaluar la utilidad del test de avidez IgG (A-IgG) para identificar la fase aguda y o crónica. Avidez es la fuerza de afinidad entre una inmunoglobulina específica y el epítope de la proteína antigénica del agente infectante, afinidad que aumenta con el tiempo. Pacientes y Métodos: Se usó un test cualitativo que mide la avidez de IgG, discriminando las dos fases. A 35 pacientes con diagnóstico clínico de TA y o TC, se les realizó IgG, IgM e A-IgG en Equipo VIDAS®. Resultados: Los pacientes con TA fueron positivos para IgM e IgG y presentaron avidez débil. Los 21 casos con TC 52 por ciento (n: 11) tuvieron IgM positivo y 100 por ciento (n: 21) tuvo IgG positiva con avidez fuerte. Discusión: Los resultados confirman que el test de A-IgG puede ser de gran utilidad en el diagnóstico de TA, concordancia: 100 por ciento con test de referencia (IgM cualitativa + IgG cuantitativa). El resultado está disponible en menos de 24 hrs, pudiendo ser útil en el diagnóstico de TA en mujeres embarazadas.

Colonización nasal bacteriana en población sana de la ciudad de Santiago de Chile: ¿existe portación de Staphylococcus aureus meticilino resistente comunitario? / Nasal bacterial colonization in healthy people of the city of Santiago of Chile: is there nasal carriage of community methicillin resistant Staphylococcus aureus?

Introducción: No existe consenso en cuanto a qué se considera flora nasal normal. Recientemente, ha emergido Staphylococcus aureus meticilino resistente comunitario (MRSA-com) en personas sin factores de riesgo conocido, produciendo una alarma sanitaria a nivel mundial. Objetivo: Determinar la colonización nasal bacteriana y evaluar la presencia de MRSA-com. Material y método: Estudio prospectivo descriptivo, entre octubre de 2007 y octubre de 2008, en población sana. Se realizó toma de muestra de secreción nasal, incubación e identificación bacteriana por métodos convencionales. Resultados: Población estudiada con promedio de edad 37,6 +/-15,8 años, 55 por ciento de sexo femenino, y 37,1 por ciento tabaquismo activo. Se obtuvo 73 por ciento de cultivos positivos. Se identificaron 18 especies bacterianas, siendo las más frecuentes Staphylococcus coagulasa negativo (53 por ciento) y Staphylococcus aureus (22,7 por ciento). Se detectó sólo un caso de MRSA, cuyo análisis genético fue negativo para demostrar su origen comunitario. Discusión: Existe una alta tasa de portación nasal de S coagulasa negativo y S aureus, similar a lo reportado por la literatura internacional. Pese a que la prevalencia encontrada para S aureus es la habitual, no se encontraron muestras positivas a MRSA-com. Lo anterior indica que aún no existe en Chile la diseminación de clones de MRSA-com.

Introduction: Doesn't exists agreement about normal nasal flora. Recently it has emerged community-associated methicillin-resistant Staphylococcus aureus in people without known rísk factors, producing a global health scare. Aim: Look for normal nasal flora and test the presence oí MRSA-com. Material ana method: Descriptive and prospective study, between October 2007 and October 2008, in healthy people. Was taken a sampling from nasal secretion, incubation and bacterial identification by conventional methods. Results: Studied population, average age 37.6 +/-15.8years, 55 percent témale and 37.1 percent active smoking. We obtained 73 percent of positive cultures. We identified 18 bacterial species, the most common was Staphylococcus coagulase-negative (53 percent) and Staphylococcus aureus (22.7 percent). Was detected only one case ofMRSA, and his genetic test was negative to prove community origin. Discusión: There is a high rate of nasal carriage of Staphylococcus coagulase-negative, like to that reponed by international literature. Although the prevalence found for S aureus is the usual, there were no MRSA-com positive samples. This indicates that in Chile there is still no spread of clones of MRSA-com.

Descripción de los Procesos de Evaluación en la Escuela de Medicina de la Pontificia Universidad Católica de Chile: Experiencia de 10 años / Description of Assessment Processes at the Medical School of the Pontificia Universidad Católica de Chile: A Ten year experience

Globalization of health care seems to be irreversible and beyond cultural differences and local realities; consequently, medical education needs to have a common set of core principles or standards that may be applied worldwide. The aim of participating in assessment processes is to guarantee that medical education takes place in a sufficiently rich environment to promote extensive academic purposes. The Medical School of the Pontificia Universidad Católica de Chile (PUC) participated in three assessment processes that included three stages: internal assessment, external assessment, and accreditation judgment. Two of these assessments were voluntarily carried out following the standards set by the Liaison Committee on Medical Education-LCME, and they took place in 1997 and 2007. The other assessment was based on standards set by the Chilean accrediting organism, the National Committee for Undergraduate Program Accreditation (Comité Nacional de Acreditación de Pregrado-CNAP) and took place in the year 2001. In all three experiences, internal assessment was the most enriching stage, stimulating refections among students and teachers in order to recognize areas of strengths and weaknesses. External assessment processes, especially those based on international standards, are very important for the institutional and program development of Medical Schools. The PUC Medical School on its whole learnt how to carry out an assessment process and was able to improve several weaknesses without pressure, moving from quality assurance to quality enhancement. The present paper analyzes the major challenges involved in an external assessment process.

[Evaluation of an IgG avidity commercial test: contribution to diagnosis of primary infection caused by Toxoplasma gondii]. / Evaluación de un test comercial de avidez de IgG: Aporte al diagnóstico de primoinfección por Toxoplasma gondii.

INTRODUCTION: Toxoplasmosis (T) is a major chronic parasitic infection in immunocompromised patients and pregnant women. It is important to discriminate between acute phase (AT) and chronic phase (CT). Diagnosis is serological in immunocompetent patients (concentration of IgG and IgM). OBJECTIVE: To evaluate the utility of an IgG avidity test (A-IgG) to identify the acute and chronic stage. Avidity is the strength of affinity between a specific immunoglobulin and the protein antigenic epitope of the infecting agent, an affinity that increases over time. PATIENTS AND METHODS: We used a qualitative kit that measures the avidity of IgG, discriminating the two phases. In 35 patients with clinical diagnosis of AT and/or CT, IgG, IgM and IgG A (VIDAS®) were performed. RESULTS: Patients with AT were positive for IgM and IgG, but presented weak avidity. In the 21 cases with CT, 52% (n: 11) were IgM positive and 100% (n: 21) had positive IgG with strong avidity. DISCUSSION: The results confirm that the test of A-IgG may be useful in the diagnosis of AT, and has 100% concordance with reference test (qualitative IgM + quantitative IgG). The result is available within 24 hrs, and may be useful in diagnosis of AT in pregnant women.

Análisis retrospectivo del rendimiento de Amplicor-PCR® para la detección de Mycobacterium tuberculosis en muestras respiratorias y no respiratorias con baciloscopia negativa: A retrospective analysis / Assessment of the Amplicor PCR® for the detection of Mycobacterium tuberculosis in smear negative respiratory and non respiratory specimens

Background: Commercial polymerase chain reaction (PCR) kits are widely accepted for analysis of smear positive respiratory specimens, but the sensitivity is variable for smear negative ones. Objective: To assess the PCR method usefulness in smear negative respiratory and non respiratory specimens. Methods: We compared the PCR results (AMPLICOR MTB test™, Roche) of 235 specimens subjected to culture in Loewenstein-Jensen agar (as the gold standard). Results: 181 (76 percent) were respiratory and 54 (24 percent) extra-respiratory specimens. The sensitivity was 88 percent) and 50 percent>, respectively, specificity and PPV was 100 percent> in both cases. NPV was 99.4 percent> in respiratory specimens and 96.1 percent in non-respiratory specimens. Conclusions: The good performance of this PCR in smear negative respiratory specimens allows the clinician to take decisions based on the result of this exam. In extra-respiratory specimens the contribution is important only when the PCR result is positive.

Susceptibilidad antimicrobiana de Campylobacter jejuni aislado de coprocultivos en Santiago de Chile / Antimicrobial susceptibility of Campylobacter jejuni isolates from stool cultures in Santiago, Chile

Campylobacter jejuni is a common agent of enterocolitis in humans. Campy lobacteriosis has been recognized as a zoonotic disease whose reservoir is the intestinal flora of poultry. The reposition of fluid and electrolytes is the recommended treatment, and antimicrobials are required only in severe and/or in prolonged disease. Given the emergence of resistance to drugs commonly used in the treatment of acute diarrhea, we studied the antimicrobial susceptibility of 73 strains oí Campylobacter jejuni isolated from stool culture. The antimicrobials tested were: erythromycin, azithromycin, ampicillin and ciprofloxacin. Of the 73 strains tested by E-test, 32.4 percent were resistant to ciprofloxacin and 6.4 percent were resistant to ampicillin. Resistance to erythromycin and azithromycin was not detected. The surveillance of antimicrobial resistance of Campylobacter jejuni is important in the evaluation of empirically used antimicrobials in the treatment of bacterial enterocolitis.

[Universal or broad-range polymerase chain reaction (PCR): a contribution to the detection and identification of bacteria and fungi in clinical practice]. / "PCR universal o de amplio espectro": un aporte a la detección e identificación de bacterias y hongos en la práctica clínica.

The use of techniques for the detection of nucleic acids such as the polymerase chain reaction (PCR) has had a major impact on microbiological analysis, playing an important role in the clinical laboratory. Most of the techniques currently used are designed for specific detection of a particular microorganism. However, infectious agents can also be identified even if genus or species are unknown, using universal primers to amplify bacterial or fungal DNA and then identify the species by sequence (universal or wide spectrum PCR). This methodology is applied in cultures that are difficult to identify using phenotypic techniques, and more recently it is also being used directly in clinical samples, where the detection and identification of the infectious agent by traditional techniques is difficult or not possible.

PCR universal o de amplio espectro: Un aporte a la detección e identificación de bacterias y hongos en la práctica clínica / Universal or broad-range polymerase chain reaction (PCR): A contribution to the detection and identification of bacteria and fungi in clinical practice

The use of techniques for the detection of nucleic acids such as the polymerase chain reaction (PCR) has had a major impact on microbiological analysis, playing an important role in the clinical laboratory. Most of the techniques currently used are designed for specific detection of a particular microorganism. However, infectious agents can also be identified even if genus or species are unknown, using universal primers to amplify bacterial or fungal DNA and then identify the species by sequency (universal or wide spectrum PCR). This methodology is applied in cultures that are difficult to identify usingphenotypic techniques, and more recently it is also being used directly in clinical samples, where the detection and identification of the infectious agent by traditional techniques is difficult or not possible.

El uso de técnicas para la detección de ácidos nucleicos como la reacción en cadena de la polimerasa (PCR) ha tenido un gran impacto en el diagnóstico microbiológico, ocupando un lugar importante en el laboratorio clínico. La mayoría de ¡as técnicas en uso han sido diseñadas para la detección específica de un microorganismo. Sin embargo, también es posible identificar el agente etiológico aunque se desconozca la especie o el género, utilizando partidores universales para amplificar el ADN de bacterias y hongos, y luego secuenciar para identificar la especie (PCR universal o de amplio espectro). Esta metodología se aplica en cultivos difíciles de clasificar por técnicas fenotípicas, pero también se ha comenzado a utilizar directamente en muestras clínicas, en las que la detección e identificación del agente infeccioso por técnicas tradicionales resulta difícil o no es posible.

[Etiology of febrile neutropenia episodes among cancer patients from Hospital Clinico Universidad Catolica, Santiago-Chile]. / Etiología de episodios de neutropenia febril en pacientes adultos con cáncer hematológico y de órganos sólidos en el Hospital Clínico Universidad Católica, Santiago-Chile.

INTRODUCTION: The surveillance of febrile neutropenia (FN) episodes in every center allows adapt the antibiotic therapy guidelines to local epidemiology. AIM: To characterize clinical features and compare the FN etiology between hematological cancer (HC) and solid organ cancer (SOC) in our center. PATIENTS AND METHODS: Surveillance study in adult patients with FN admitted to Hospital Clinico Universidad Católica, in Santiago, Chile, from January 2004 to August 2007. RESULTS: 154 FN episodes corresponding to 87 patients were included. Mean age: 47 +/- 6 years-old; 71% had HC and 29% SOC. A clinical and/or microbiologically documented infection was recognized in 76%. Gastrointestinal 31.5%, upper respiratory 30.3% and lower respiratory 16.9% were the more frequent clinical focus. In 30.5% blood culture resulted positive: gram negative rods 51%, gram positive cocci 41% and yeasts 8%; being Escherichia coli 22%, S. coagulase negative (SCoN) 20% and Klebsiella pneumoniae 12% most frequent bacteria; 22.2% Enterobacteriaceae were ESBL producers and 55.6% 5CoN were methicillin resistant. In 18.3% of FN episodes the etiology was not established. Highest mortality was observed in episodes with microbiologically documented infection (14.5% vs 1.3%, p < 0.005). A clinical observed focus and positive blood cultures were more frequently obtamed among HC than SOC associated episodes: 37.3% vs 13.6%; (p < 0.01) and 67.2% vs 50%; (p = 0.045), respectively. CONCLUSIONS: The etiological profile of FN in our center and the necessity to continue the surveillance was described. Future studies are needed regarding risk factors of invasive infection that have worst prognosis.

[Multicenter study on the monitoring of in vitro susceptibility to tigeeyeline in Santiago, Chile]. / Estudio multicéntrico de la vigilancia de la susceptibilidad in vitro a tigeciclina en Santiago de Chile.

The objective of this multicenter study was to determine tigecycline susceptibility rates, measured by agar diffusion, in nine hospitals in Santiago and to compare these rates with other antimicrobials. Each center studied 20 strains per month. All intermediate and fully resistant strains as well as 10% of susceptibile strains were also studied by the broth microdilution method. Overall, 2301 strains were studied displaying the following susceptibility rates for tigecycline: 100% for Streptococcus sp, Enterococcus sp, and E. coli respectively, 99.8% for Staphylococcus sp, 93% for Klebsiella and 80% for Acinetobacter baumarmii. For Proteus, Providencia and Morganella the susceptibility rates were 4%. For cefotaxime-resistant Klebsiella and imipenem-resistant A. baumarmii susceptibility rates were 95% and 80% respectively. The agar diffusion and broth dilution method were 100% concordant for tigecycline susceptible strains but only 27% for resistant or intermediate strains represented mostly by Acinetobacter baumannii. The majority of these strains (57/59) proved to be susceptible after retesting. The great majority (96,6%) of strains tested from nine Chilean hospitals proved to be susceptible to tigecycline with exception for Proteus, Providencia and Morganella (66% resistance). Using the agar diffusion method for measuring tigecycline susceptibility to A. baumannii may be misleading.