Detección de genes de virulencia del patotipo enteroagregativo en cepas de Escherichia coli aisladas de fuentes de agua subterránea de la provincia del Chaco, Argentina / Detection of virulence genes of the enteroaggregative pathotype in Escherichia coli strains isolated from groundwater sources in the province of Chaco, Argentina

En la provincia del Chaco, el agua subterránea representa una fuente alternativa, y muchas veces única, para el consumo humano; esta es utilizada en el 14 % de los hogares. A pesar de que se reconoce el riesgo de la exposición al agua contaminada, la prevalencia de los diferentes patotipos de Escherichia coli en ambientes acuáticos no ha sido bien caracterizada. E. coli enteroagregativo (ECEA) es un patógeno emergente cuya importancia en la salud pública mundial se incrementó y quedó claramente establecida en los últimos años. El objetivo del presente trabajo fue detectar la presencia de ECEA típico mediante el reconocimiento de los factores de virulencia aap, AA probe y aggR por reacción en cadena de la polimerasa, en fuentes de agua subterráneas de la provincia del Chaco. Se identificó E. coli en 36 (38,7 %) de las 93 muestras estudiadas, provenientes de diferentes localidades. De esos 36 aislamientos, se identificaron 6 (16,7 %) portadores de los genes de ECEA, lo que representa una prevalencia del 6,4 % considerando las 93 fuentes de agua subterránea estudiadas. De esos 6 aislamientos, 3 eran portadores del gen aap, 2 del gen AA probe y uno de la combinación aggR/aap. El presente trabajo representa el primer aporte en el estudio de la presencia y distribución de genes de virulencia de ECEA en fuentes de agua subterránea de la región.

Groundwater is an important source of drinking water for many communities in Northern Argentina; particularly, in the province of Chaco, where about 14 % of households use this natural resource. Enteroaggregative Escherichia coli is an emerging pathogen whose global importance in public health has increased in recent years. Despite the significant risk of disease linked to contaminated water exposure, the prevalence of E. coli pathotypes in aquatic environments is still not so well defined. The aim of the present study was to detect the presence of typical enteroaggregative E. coli through the recognition of its virulence factors aap, AA probe and aggR by molecular techniques. A total of 93 water samples from different small communities of Chaco were analyzed. E. coli was identified in 36 (38.7 %) of the tested samples. Six strains isolated from different samples harbored the studied genes. Of these 6 isolates, 3 carried the aap gene, 2 the AA probe and the last one the combination of aap/aggR genes. The prevalence of E. coli isolates harboring enteroaggregative virulence genes in groundwater sources was 6.4 %. This work represents the first contribution to the study of the presence and distribution of virulence genes of EAEC in groundwater sources in this region of Argentina.

Determinants of emergency contraception non-use among women in unplanned or ambivalent pregnancies / Determinantes del no uso de la anticoncepción de emergencia entre mujeres con embarazo no planeado u ambivalente / Determinantes do não uso da anticoncepção de emergência entre mulheres com gravidez não planejada ou ambivalente

Objective To analyze the determinants of emergency contraception non-use among women in unplanned and ambivalent pregnancies. Method Cross-sectional study with a probabilistic sample of 366 pregnant women from 12 primary health care units in the city of São Paulo, Brazil. A multinomial logistic regression was performed, comparing three groups: women who used emergency contraception to prevent ongoing pregnancies (reference); women who made no use of emergency contraception, but used other contraceptive methods; and women who made no use of any contraceptive methods at all. Results Cohabitation with a partner was the common determinant of emergency contraception non-use. No pregnancy risk awareness, ambivalent pregnancies and no previous use of emergency contraception also contributed to emergency contraception non-use. Conclusion Apart from what is pointed out in the literature, knowledge of emergency contraception and the fertile period were not associated to its use. .

Objetivo Analizar los determinantes del no uso de la anticoncepción de emergencia entre las mujeres con embarazo no planeado o ambivalente. Método Estudio transversal en una muestra probabilística de 366 mujeres embarazadas de 12 Unidades Básicas de Salud de São Paulo. Mediante regresión logística multinomial, se comparó tres grupos de mujeres: aquellas que usaron la anticoncepción de emergencia para prevenir el embarazo en curso (referencia), aquellas que usaron algún método anticonceptivo, pero no la anticoncepción de emergência; y aquellas que no usaron ningún método. Resultados Los hallazgos mostraron que vivir com la pareja fue el determinante común del no uso de la anticoncepción de emergencia. No tener conciencia del riesgo de embarazo, estar en un embarazo ambivalente y nunca tener utilizado la anticoncepción de emergencia también fueron associados con su no uso para prevenir el embarazo en curso. Conclusión Contrariamente a lo que reporta la literatura, el conocimiento de la anticoncepción de emergencia y el período fértil no mostró asociación con el no uso. .

Objetivo Analisar os determinantes do não uso da anticoncepção de emergência entre mulheres com gravidez não planejada ou ambivalente. Método Estudo transversal com amostra probabilística de 366 gestantes de 12 Unidades Básicas de Saúde da cidade de São Paulo. Por meio de regressão logística multinomial, compararam-se três grupos de mulheres: as que usaram anticoncepção de emergência para prevenir a gravidez em curso (referência); as que usaram algum método contraceptivo, mas não anticoncepção de emergência; e as que não usaram nenhum método. Resultados Os achados mostraram que morar com o parceiro foi o determinante comum do não uso da anticoncepção de emergência. Não ter consciência do risco de engravidar, estar em uma gravidez ambivalente e nunca ter usado anticoncepção de emergência também foram associados ao seu não uso para prevenir a gravidez em curso. Conclusão Diferentemente do que relata a literatura, o conhecimento sobre anticoncepção de emergência e sobre o período fértil não mostrou qualquer associação ao não uso. .

The ability of haemolysins expressed by atypical enteropathogenic Escherichia coli to bind to extracellular matrix components

Typical and atypical enteropathogenic Escherichia coli (EPEC) are considered important bacterial causes of diarrhoea. Considering the repertoire of virulence genes, atypical EPEC (aEPEC) is a heterogeneous group, harbouring genes that are found in other diarrheagenic E. coli pathotypes, such as those encoding haemolysins. Haemolysins are cytolytic toxins that lyse host cells disrupting the function of the plasma membrane. In addition, these cytolysins mediate a connection to vascular tissue and/or blood components, such as plasma and cellular fibronectin. Therefore, we investigated the haemolytic activity of 72 aEPEC isolates and determined the correlation of this phenotype with the presence of genes encoding enterohaemolysins (Ehly) and cytolysin A (ClyA). In addition, the correlation between the expression of haemolysins and the ability of these secreted proteins to adhere to extracellular matrix (ECM) components was also assessed in this study. Our findings demonstrate that a subset of aEPEC presents haemolytic activity due to the expression of Ehlys and/or ClyA and that this activity is closely related to the ability of these isolates to bind to ECM components.

Patogénesis molecular, epidemiología y diagnóstico de Escherichia coli enteropatógena / Molecular pathogenesis, epidemiology and diagnosis of enteropathogenic Escherichia coli

Escherichia coli enteropatógena (EPEC) es una de las principales causas de diarrea en niños menores de dos años en países en vías de desarrollo. La principal característica histopatológica de la infección es una lesión que induce la EPEC en el intestino conocida como la lesión A/E (adherencia y eliminación). Las bacterias se adhieren a los enterocitos y permiten la acumulación de la actina del citoesqueleto en la región apical de la célula, hasta formar una estructura de tipo "pedestal" y causar la eliminación de las microvellosidades intestinales. A pesar de que se conoce de modo detallado el proceso de formación de los pedestales de actina, aún no se ha esclarecido el mecanismo global de la diarrea que induce EPEC. La diarrea se ha vinculado con: a) la destrucción de las microvellosidades del enterocito, b) la salida masiva de iones hacia la luz intestinal y c) la secreción de alguna enterotoxina. En estudios realizados en países en vías de desarrollo se ha demostrado que EPEC es uno de los principales agentes participantes en la diarrea infantil, con elevadas tasas de morbilidad y mortalidad. El diagnóstico microbiológico de la infección se realiza con metodologías adicionales a las utilizadas con regularidad en el laboratorio de microbiología clínica, entre ellas las siguientes: a) serotipificación, b) ensayo de adherencia, c) prueba de FAS (tinción fluorescente para actina) y d) detección específica de genes que codifican a proteínas incluidas en la patogénesis, como el bfpA y eae. Un objetivo de esta revisión es actualizar los avances observados en la patogénesis molecular de la infección por EPEC, las metodologías para el diagnóstico microbiológico y la epidemiología en México y otros países en vías de desarrollo.

Enteropathogenic Escherichia coli (EPEC) is a leading cause of diarrhea in infants less than two years of age in developing countries. To induce diarrhea EPEC uses several virulence factors acting on a still unknown and mysterious mechanism. The hallmark of EPEC infection is a histological intestinal alteration known as the attaching and effacing (A/E) lesion. The bacterium attaches intimately to the enterocyte and induces assembly of cytoskeleton intracellular actin on the cellular surface. Rearrangements of the actin cytoskeleton form a pedestal-like structure where bacterium tightly cups the cells, leading to degeneration of brush border microvilli. Although the mechanism of EPEC-induced pedestal formation has been dissected in detail, the overall mechanism of diarrhea is still obscure. It is believed that EPEC-mediated secretory diarrhea is related to a) intestinal microvilli effacement, b) massive loss of intracellular ions into the intestinal milieu and c) secretion of an EPEC enterotoxin. Epidemiological studies conducted in developing countries have shown that EPEC is one of the main bacteria frequently isolated from children with diarrhea, causing high morbidity and mortality rates. The microbiological diagnosis of EPEC-induced disease is performed with analytic methodologies different from those used by the standard microbiology laboratory, the most relevant being: a) serotypification, b) the adherence assay, c) FAS test, and d) the specific detection of virulence-involved genes (bfpA and eae genes) using molecular biology techniques. The purpose of this review is to update the most recent findings regarding the molecular pathogenesis of EPEC, its epidemiology in Mexico as well as other developing countries, and also the developed methodology for the diagnosis of EPEC infection.