Pathogenicity of non-pigmented and pigmented isolates of P. aeruginosa during long-term storage

Abstract

The aim: to study the pathogenicity of non-pigmented P. aeruginosa isolates compared to those that synthesize pigment during long-term storage for broiler chickens. Materials and methods. Bacteriological studies were carried out in accordance with generally accepted methods. Initially, P. aeruginosa and other bacterial microflora were isolated from poultry farms, pathological material from poultry. The type of microorganisms was identified using Bergey's identifier. The obtained isolates were examined by morphological characteristics (according to Gram), tincture, cultural, biochemical, pathogenic properties and sensitivity of selected cultures to antibiotics were studied. After the expiration of 3 years, the main biological properties of the isolates were monitored. To establish pathogenic properties, a bioassay was performed on white mice and one-week-old broiler chickens of the Cobb 500 cross (intraperitoneally by washout from daily agar culture at a dose of 0.2 cm3, which corresponds to the previously established LD50). The results. With parenteral infection by washout from agar daily culture of pigmentless isolates at a dose of LD50, chickens died within the first - second day, in this case 87.50 % of the cultures showed pathogenicity. Experimental parenteral infection with washings from a daily culture of pigmented isolates of P. aeruginosa at a dose of LD50 led to the death of one-week-old chickens within 24-48 hours, in this case 75.00 % of the isolates showed pathogenicity. Clinical and pathological signs of infection with pigmented and non-pigmented P. aeruginosa isolates were similar. Conclusions. A comparative analysis of cases of pathogenicity of non-pigmented and pigmented isolates of P. aeruginosa on one-week-old broiler chickens of the Cobb-500 cross was carried out. In the experiment, we found that among the non-pigmented isolates, compared to the pigmented pathogenic isolates, 12.5 % more were detected in chickens. This emphasizes the importance of differential diagnosis for pseudomonosis, because infection with non-pigmented strains often goes undiagnosed