Avian pathogenic Escherichia coli (APEC) strains cause different types of systemic extraintestinal infections in poultry, collectively termed colibacillosis, which can cause significant economic losses in the poultry industry. To date, there have been no descriptions of genes or characteristics that allow for the classification of avian strains pathotypes responsible for causing specific diseases in their hosts. In this study we aimed to characterize avian E. coli strains representing 4 groups, including one of commensal strains (AFEC – Avian Fecal Escherichia coli) and 3 groups of APEC strains, where each group is responsible for causing a different disease syndrome in their respective hosts (septicemia, omphalitis and swollen head syndrome). We chose to examine several biological characteristics of these strains including: adhesion to eukaryotic cells, pathogenicity levels according to the lethal dose (50%) assay, phylogenetic group and virulence gene profiles. The comparison of strains based on these genotypic and phenotypic traits, using multivariate statisticals tools and complex networks, allowed us to infer information about the population structure of the studied groups. Our results indicate that APEC strains do not constitute a unique homogeneous group, but rather a structured set of subgroups, where each one is associated with a specific infectious syndrome which can possibly be used to define pathotypes or subpathotypes within APEC strains. These results offer new possibilities with which to study the genes responsible for various pathogenetic processes within APEC strains, and for vaccine development. It may be important to consider these subgroups when developing a vaccine in an effort for obtain cross protection, which has not yet been successfully accomplished when working with APEC strains.

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Steroid 21-hydroxylase defi ciency (21-OHD) accounts for more than 90% of congenital adrenal hyperplasia. CAH newborn screening, in general, is based on 17-hydroxyprogesterone dosage (17-OHP), however it is complicated by the fact that healthy preterm infants have high levels of 17-OHP resulting in false positive cases. We report on molecular features of a boy born pre-term (GA = 30 weeks; weight = 1,390 g) with elevated levels of 17-OHP (91.2 nmol/L, normal < 40) upon neonatal screening who was treated as having CAH up to the age of 8 months. He was brought to us for molecular diagnosis. Medication was gradually suspended and serum 17-OHP dosages mantained normal. The p.V281L mutation was found in compound heterozygous status with a group of nucleotide alterations located at the 3` end intron 4 and 5' end exon 5 corresponding to the splice site acceptor region. Molecular studies continued in order to exclude the possibility of a nonclassical 21-OHD form. The group of three nucleotide changes was demonstrated to be a normal variant since they failed to interfere with the normal splicing process upon minigene studies. A defi ciência de 21-hidroxilase (21-OHD) é uma doença autossômica recessiva que contribui com mais de 90% dos casos de hiperplasia congênita da adrenal. O teste de dosagem de 17-hidroxiprogesterona (17-OHP) por radioimunoensaio em amostras de sangue colhidas em papel de fi ltro tem sido o método mais usado nos programas de triagem neonatal. No entanto, essa triagem pode apresentar alto número de falso-positivos pelo fato de os recém-nascidos prematuros apresentarem dosagens mais elevadas deste esteróide. Apresentamos aqui os estudos moleculares de uma criança, sexo masculino, nascida pré-termo (IG = 30 sem; peso = 1.390 g) que apresentava valores elevados de 17-OHP sérica (91,2 nmol/L, normal < 40) na triagem neonatal e que foi tratada como portadora da forma clássica da 21-OHD até a idade de 8 meses quando nos foi encaminhada para diagnóstico molecular. A terapia foi, então, gradativamente descontinuada, sendo que as concentrações séricas de 17-OHP se mantiveram normais. A mutação p.V281L foi encontrada em heterozigose composta com um grupo de alterações no terminal 3' do íntron 4 e no terminal 5' do éxon 5 correspondendo à região do sítio aceptor de splicing. A análise do gene CYP21A2 prosseguiu para se excluir a possibilidade de a criança ser afetada com a forma não-clássica de 21-OHD. Pela análise de minigene fi cou demonstrado que o grupo de três trocas nucleotídicas não afeta o processo normal de transcrição. Concluindo, a criança é apenas heterozigota da mutação p.V281L sem necessidade de tratamento.

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