The aim of this study was to perform a current molecular characterization of bovine pathogenic Escherichia coli strains isolated from random samplings in Argentinean dairy farms. Rectal swabs were obtained from 395 (63.7 %) healthy and 225 (36.3 %) diarrheic calves, belonging to 45 dairy farms in Cordoba Province, Argentina. E. coli isolates were examined for virulence genes (f5, f41, f17, sta, stb, lt, eae, vt) using PCR and the prevalence of E. coli virulence profiles was spatially described in terms of spatial distribution. A total of 30.1 % isolates were found to be positive for at least one of the virulence genes. Depending on the different gene combinations present, 11 virulence profiles were found. Most of the isolates analyzed had a single gene, and no combination of fimbrial and enterotoxin gene was predominant. There was no association between the frequency and distribution of E. coli virulence genes and calf health status. Most of the virulence profiles were compatible with ETEC strains and showed a homogeneous distribution over the sampled area. A clustering pattern for E. coli virulence profiles could not be recognized. This work provides updated information on the molecular characterization of pathogenic E. coli strains from dairy herds in Cordoba, Argentina. These findings would be important to formulate prevention programs and effective therapies for diarrhea in calves caused by E. coli.

El objetivo de este trabajo fue realizar una caracterización molecular actualizada de cepas patógenas bovinas de Escherichia coli aisladas de un muestreo aleatorio en tambos de una de las principales zonas lecheras de Argentina. Se obtuvieron hisopados rectales de 395 terneros neonatos sanos (63,7 %) y 225 diarreicos (36,3 %) pertenecientes a 45 tambos de la provincia de Córdoba, Argentina. Los genes de virulencia f5, f41, f17, sta, stb, lt, eae y vt se analizaron mediante PCR y se investigó la prevalencia de los perfiles de virulencia en función de la distribución geográfica. La prevalencia de aislamientos de E. coli patogénicos con al menos un gen de virulencia fue del 30,1 %. Once perfiles de virulencia fueron identificados, dependiendo de la combinación de genes presentes. La mayor parte de las muestras presentó un solo gen de virulencia, y no predominó ninguna combinación de genes de fimbrias y toxinas. No hubo asociación entre la frecuencia y la distribución de los genes de virulencia y el estado de salud de los terneros. La mayoría de los perfiles de virulencia fueron compatibles con cepas ECET y se distribuyeron cubriendo toda el área geográfica muestreada. No se reconoció ningún patrón de agrupamiento espacial para dichos perfiles. Este trabajo provee información actualizada sobre la caracterización molecular de E. coli patógena en rodeos lecheros de Córdoba, Argentina. Estos resultados serían importantes para formular programas preventivos y terapias eficaces contra la diarrea bovina causada por E. coli.

The enterotoxigenic and porcine enteropathogenic Escherichia coli (ETEC and PEPEC) strains are agents associated with swine neonatal diarrhea, causing economic losses in swine production. The main goal of this study was to identify virulence genes of ETEC, verotoxigenic (VTEC) and PEPEC in intestinal strains responsible for swine diseases, by molecular typing using PCR in newborn piglets from an intensive farm system. Two hundred and sixty seven rectal swabbings from 7-15 days- old Landrace x Large White crossbred piglets were taken, and 123 randomly selected samples, biochemically compatible with E. coli, were tested for E. coli virulence genes by PCR. A frequency (%) compatible with: 68 ETEC, 24 VTEC, and 8 EPEc were found. Of all E. coli strains studied, 19.51 % carried at least one virulence gene. These data showed conclusively that, in spite of the application of strict sanitary measures in the intensive farm, genes encoding virulence factors of intestinal pathogens compatible with ETEC are still dETECted; therefore these strains will probably keep circulating among animals.

El objetivo del trabajo fue identificar genes de virulencia de cepas intestinales de Escherichia coli de los grupos enterotoxigénico (ETEC), verotoxigénico (VTEC) y enteropatogénico porcino (PEPEC), responsables de patologías en cerdos, mediante tipificación molecular por PCR. Para ello se trabajó en un criadero intensivo, donde se tomaron 267 hisopados rectales de lechones cruza Landrace por Large White de 7-15 días de edad. Del total de aislamientos obtenidos se seleccionaron al azar 123 de ellos, bioquímicamente compatibles con E. coli, los que fueron analizados por PCR. La frecuencia de genes compatibles con ETEC, VTEC y PEPEC fue de 68 %, 24 % y 8 %, respectivamente. De las cepas de E. coli seleccionadas, el 19,51 % portaban al menos un gen codificante de un factor de virulencia. Estos hallazgos muestran de manera concluyente que la aplicación de estrictas medidas sanitarias en el criadero en estudio no logró evitar la presencia de genes que codifican factores de virulencia de patógenos intestinales compatibles con ETEC. Es probable que las cepas circulen entre los animales.

Os objetivos deste estudo foram determinar a prevalência de Cryptosporidium spp. e Giardia spp., a presença de aglomerados, a distribuição espacial de acordo com o tipo de solo e padrões de eliminação de cistos e oocistos em bezerros de propriedades leiteiras em Córdoba, Argentina. Amostras fecais foram colhidas de 620 bezerros com menos de sete semanas de idade, provenientes de 43 propriedades leiteiras e examinadas pelas técnicas de formol-éter e Ziehl-Neelsen modificada. Foram realizadas uma análise univariada e o teste de Kruskal-Wallis e, em seguida, uma análise multivariada com a intensidade de eliminação de cistos e oocistos, como um evento. A presença de aglomerados foi determinada com o método de varredura e a análise espacial foi realizada para explorar a sobreposição de rebanhos com alta prevalência e tipo de solo. A prevalência de Cryptosporidium spp. e Giardia spp. foi de 19,35% (IC 95%: 16,14; 22,54) e 34,50% (IC 95%: 30,69; 38,34), respectivamente. A probabilidade de infecção por Cryptosporidium spp. foi quase quatro vezes maior para bezerros com menos de 2 semanas em comparação com os bezerros mais velhos (RR: 3,78, IC 95% 2,27; 6,26). O mesmo padrão de infecção relacionada à idade foi observado para Giardia spp. (RR: 1,33, IC 95% 1,02; 1,75). Foi encontrado um aglomerado primário com alta prevalência de Cryptosporidium spp., e rebanhos com alta prevalência foram localizados em solos mal drenados.

The objectives of this study were to estimate calf and herd prevalence of Cryptosporidium spp. and Giardia spp., the herd prevalence clustering, spatial distribution according to soil type and shedding patterns in dairy calves from Cordoba, Argentina. Six hundred twenty calves younger than 7 weeks of age from 43 dairy herds were sampled. Samples were processed with the formol-ether and modified Ziehl-Neelsen techniques. Univariate analysis and Kruskall-Wallis tests were used. Factors associated were subjected to multivariate analysis with calf shedding intensity as the response variable. Clustering of herd prevalence was assessed by a scan method, and spatial analysis was applied to explore the overlapping of high prevalence herds and soil type. Overall calf prevalence for Cryptosporidium spp. oocysts and Giardia spp. cysts were 19.35% (95% CI: 16.14; 22.54) and 34.50% (95% CI: 30.69; 38.34), respectively. Calves younger than two weeks of age were almost four times more likely to be infected with Cryptosporidium, in comparison to older ones (RR: 3.78, 95% CI: 2.27; 6.26). Giardia spp. shedding showed a similar age pattern (RR: 1.33, 95% CI: 1.02; 1.75). A primary cluster of high Cryptosporidium prevalence was found, and high prevalence herds were located in areas with poor drained soil.