Invasive Species Compendium

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Abstract Full Text

Natural coinfection of Pseudomonas aeruginosa and Enteroaggregative Escherichia coli in a feral pigeon (Columba livia).


This article describes a case of natural coinfection of Pseudomonas aeruginosa and Enteroaggregative Escherichia coli in a feral pigeon. A sick feral pigeon was admitted at the Laboratory of Ornithological Studies, State University of Ceará, Fortaleza, Brazil. The pigeon was euthanized due to poor prognosis and submitted to necropsy, and samples were collected for microbiological and histopathological examinations. The procedure was performed aseptically and samples were collected from intestine, liver, spleen, heart and lung. Bacterial isolation was performed with culture media selective for Gram-negative bacteria and strains were identified biochemically. Histopathological examination was performed with conventional method and slides were stained with hematoxylin and eosin. DNA from E. coli isolates was extracted with simples boiling method and submitted to uniplex conventional polymerase chain reaction (PCR) to diagnose diarrheagenic pathotypes with specific primers for the following genes: aaiC, aatA, eaeA, stx1, stx2, eltB, estA and ipaH. Results revealed that Escherichia coli was isolated from the intestine, liver, spleen and lungs, while Pseudomonas aeruginosa was present in liver, spleen and lungs. E. coli strains from liver and spleen were positive for the aaiC gene, which is a diagnostic gene for Enteroaggregative Escherichia coli (EAEC) pathotype. Necropsy revealed the presence of several caseous lesions around the head of the bird, cellulitis in the abdominal region, hepatomegaly, splenomegaly, hemorrhagic intestine and pericarditis. Microscopical findings were most intense in liver and lung samples, presenting vascular and inflammatory alterations. Histopathological alterations indicated an acute presentation of the infections and several lesions in different organs, demonstrating the septicaemic characteristic of the microorganisms involved in this case. It is concluded that the free-living pigeon presented a natural occurring case of coinfection by Pseudomonas aeruginosa and Enteroaggregative Escherichia coli.