The presence of Pseudomonas aeruginosa is becoming more frequent in avian pathology. This microorganism has an increasing resistance to antibiotics and disinfectants. For this reason, its vertical and horizontal transmission make it an emerging infection.

The production of nodules can lead to the confusion of this pathogen with others, such as aspergillosis and salmonellosis. From a clinical point of view, some diagnostic criteria can be stated:

(1) Usually, there is a larger number of Pseudomonas' nodules, and these are smaller than Aspergillus fumigatus', and appear in a later stage (less than 21 days for Aspergillus and more than 21 days for Pseudomonas), and, unlike aspergillosis, Pseudomonas' infection causes fever.

(2) Pseudomonas' nodules are rounder, while Salmonellas' have a concave surface. Pseudomonas' infection causes clinical signs similar to those of salmonellosis, although the severity of the hepatic condition tends to be less severe in Pseudomonas.