Molecular characterization and clonal relationships among Escherichia coli strains isolated from broiler chickens with colisepticemia.

This study characterized 52 Escherichia coli isolates from distinct diseased organs of 29 broiler chickens with clinical symptoms of colibacillosis in the Southern Brazilian state of Rio Grande do Sul. Thirty-eight isolates were highly virulent and 14 were virtually avirulent in 1-day-old chicks, yet all isolates harbored virulence factors characteristic of avian pathogenic E. coli (APEC), including those related to adhesion, iron acquisition, and serum resistance. E. coli reference collection phylogenetic typing showed that isolates belonged mostly to group D (39%), followed by group A (29%), group B1 (17%), and group B2 (15%). Phylogenetic analyses using the Amplified Ribosomal DNA Restriction Analysis and pulse-field gel electrophoresis methods were used to discriminate among isolates displaying the same serotype, revealing that five birds were infected with two distinct APEC strains. Among the 52 avian isolates, 2 were members of the pandemic E. coli O25:H4-B2-ST131 clone.

Characterization of extraintestinal Escherichia coli isolated from a peacock (Pavo cristatus) with colisepticemia.

Extraintestinal infections by avian pathogenic strains of Escherichia coli (APEC) are commonly reported in poultry, but there is little information on infections by APEC in other bird species. Here we report on the characterization of extraintestinal E. coli isolated from a domesticated peacock, from the south of Brazil, that died of colisepticemia. Necropsy examination revealed congested liver, hypertrophied kidneys, peritonitis, severe typhlitis suggestive of coligranuloma, pneumonia, and airsacculitis--typical signs of colisepticemia. The isolates from lungs, kidney, heart, intestine, liver, and bone marrow all harbored the same virulence-associated factors (iucD, colV, iss, mat, fimC, ompA, traT crl, csgA vgrG, and hcp), yielded the same band pattern in amplified ribosomal DNA restriction analysis, and were allocated to the Escherichia coli Reference Collection group B1. The isolates were resistant to bacitracin, trimethoprim, and tetracycline, but displayed slight differences in their resistance to other antimicrobials. The isolates also differed in their virulence in 1-day-old chickens, but none displayed high virulence in vivo. We conclude that the peacock died of colisepticemia after it was infected with an extraintestinal E. coli strain of low virulence that nevertheless harbored virulence factors generally associated with APEC. This study represents the first characterization of an APEC isolated from a nonpoultry bird species.

Genotypes and pathogenicity of cellulitis isolates reveal traits that modulate APEC virulence.

We characterized 144 Escherichia coli isolates from severe cellulitis lesions in broiler chickens from South Brazil. Analysis of susceptibility to 15 antimicrobials revealed frequencies of resistance of less than 30% for most antimicrobials except tetracycline (70%) and sulphonamides (60%). The genotyping of 34 virulence-associated genes revealed that all the isolates harbored virulence factors related to adhesion, iron acquisition and serum resistance, which are characteristic of the avian pathogenic E. coli (APEC) pathotype. ColV plasmid-associated genes (cvi/cva, iroN, iss, iucD, sitD, traT, tsh) were especially frequent among the isolates (from 66.6% to 89.6%). According to the Clermont method of ECOR phylogenetic typing, isolates belonged to group D (47.2%), to group A (27.8%), to group B2 (17.4%) and to group B1 (7.6%); the group B2 isolates contained the highest number of virulence-associated genes. Clonal relationship analysis using the ARDRA method revealed a similarity level of 57% or higher among isolates, but no endemic clone. The virulence of the isolates was confirmed in vivo in one-day-old chicks. Most isolates (72.9%) killed all infected chicks within 7 days, and 65 isolates (38.1%) killed most of them within 24 hours. In order to analyze differences in virulence among the APEC isolates, we created a pathogenicity score by combining the times of death with the clinical symptoms noted. By looking for significant associations between the presence of virulence-associated genes and the pathogenicity score, we found that the presence of genes for invasins ibeA and gimB and for group II capsule KpsMTII increased virulence, while the presence of pic decreased virulence. The fact that ibeA, gimB and KpsMTII are characteristic of neonatal meningitis E. coli (NMEC) suggests that genes of NMEC in APEC increase virulence of strains.

Produção de leite de vacas da raça Holandesa de pequeno, médio e grande porte / Milk production of Holstein cows in small, medium and large size

O objetivo deste estudo foi avaliar o efeito do composto corporal sobre a produção de leite de vacas da raça Holandesa de primeira, segunda e terceira lactação. Para avaliação, foram usadas 133 vacas, selecionadas de um rebanho de 280 animais em lactação, classificadas como pequenas, médias e grandes, com base no composto corporal (estatura x 10 + força x 5 + profundidade x 3 + largura de garupa x 2)/20. Os dados foram coletados, entre janeiro de 2007 e outubro de 2009, de um rebanho comercial com sistema intensivo de produção de leite, localizado em Salto do Jacuí, Rio Grande do Sul, Brasil. Todas as vacas foram submetidas às mesmas condições de instalações e ordenhadas três vezes ao dia. Os dados foram obtidos com auxílio do software AFIMILK® - SAE AFIKIM. O delineamento experimental utilizado foi o inteiramente casualizado com três tratamentos (tamanho corporal). Não foi verificada interação entre a produção de leite e composto corporal. Foi observada baixa correlação entre composto corporal e produção de leite. Vacas de porte médio e grande apresentaram produção de leite similar e superior (P<0,05) às pequenas. As médias de produção de leite para vacas pequenas, médias e grandes em 305 dias foram de 8.053; 8.810 e 9.218 litros, respectivamente. Com base na totalidade das lactações avaliadas, as vacas de porte médio são mais eficientes que as demais, considerando o sistema intensivo de produção em análise.

The objective of this study was to evaluate the effect of the body size in milk production in the first, second and third lactations of Holstein cows. A total 133 cows were used, selected from a herd of 280 cows, classified as small, medium and large based on the body size composite (stature x 10 + strength x 5 + depth x 3 + rump width x 2)/20. Data were collected from January 2007 to October 2009 in a commercial herd with intensive system of milk production, located in Salto Jacuí, Rio Grande do Sul, Brazil. All cows were subjected to the same conditions of facilities management being used and milked three times a day. Data were obtained from the software Afimilk® - SAE AFIKIM. The experimental design was a completely randomized design with three treatments (body size). There was no interaction between milk production and body composite. Low correlation among body size composite and milk production was observed. Cows for medium and large size had similar on milk production superior (P<0,05) to small size. Means for 305-days milk production in the lactation were 8,053; 8,810 and 9,218 liters for small, medium and large cows, respectively. Based on the totality of lactations evaluated, cows of medium size were more efficient than the others for the intensive production system in question.