Pathogenicity studies were conducted using two bacteria (Proteus mirabilis and Pseudomonas aeruginosa) that were previously recovered from oral and cloacal swabs of red-headed rock agamas (Agama agama) living in poultry farms at Oyo State, Nigeria. Both bacteria were inoculated in two experiments having 60 broilers each. In each experiment, three groups of 15 broilers were given separately graded doses of P. mirabilis or P. aeruginosa. A group of 15 non-inoculated broilers were used in each experiment as negative controls. Clinico-haematological findings, and bacterial examination of cloacal swabs of the broilers were evaluated weekly for 5 weeks post-inoculation (PI). At necropsy, some tissues were harvested for bacteriological and histopathological examinations. Apart from the significant increase (p<0.05) recorded in the total white blood cell and heterophilic counts at week 3 and 4 PI in birds with high and medium doses of Proteus, all haematological values remain within reference intervals in Psedomonas groups. P. mirabilis and P. aeruginosa were isolated from cloacal swabs in all inoculated birds at the 3-4 weeks PI. The Proteus groups (25.0%; 15/60) showed moderate lung and liver congestion, and a few greyish white nodules on the myocardium while extensive myocardiac fiber degeneration, necrosis and loss of striation with numerous inflammatory cells were also observed. This is the first documented report of P. mirabilis induced nodular myocarditis in chickens. These findings also suggested that P. mirabilis could be pathogenic in adult broilers with possible oral transmission of this microorganism from lizards to poultry, thus, could represent a threat to human health.
Key words: Broiler chickens, Agama agama, Proteus mirabilis, Pseudomonas aeruginosa, Oyo State.
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