Case reports involving coinfection with <i>Avibacterium paragallinarum</i> and <i>Ornithobacterium rhinotracheale</i> in broiler chickens and <i>Avibacterium endocarditis</i> in broiler breeding hens in Poland

The study describes three clinical cases of infection with <i>Avibacterium</i> spp.. In case no. 1, respiratory clinical signs and high mortality (0.7–4.2% daily; total 21.2%) in Ross 308 broiler chickens were shown to be caused by coinfection with sequence type 9 of <i>O. rhinotracheale</i> presumptive serotype A and <i>A. paragallinarum</i> presumptive serotype B. The identical (pulsed-field gel electrophoresis) restriction pattern (pulsotype) of seven <i>A. paragallinarum</i> isolates indicated that infectious coryza in broilers was caused by the same clone. In cases 2 and 3, sudden increased deaths in Ross 308 broiler breeders (especially males) with lesions in the endocardium (valvular or mural endocarditis) were shown to be caused by <i>A. endocarditis</i>. Among nine antibiotics tested, florfenicol was the only antibiotic to which all <i>A. paragallinarum</i> and <i>O. rhinotracheale</i> isolates were susceptible. Out of the eight antibiotics tested, 11 <i>A. endocarditis</i> isolates from both clinical cases of infective endocarditis were susceptible to penicillin, amoxicillin, doxycycline and florfenicol. The <i>A. endocarditis</i> isolates tested in both clinical cases had different PFGE patterns (pulsotypes), but identical within a case. The causes of infectious coryza and infective endocarditis in the cases presented have not been determined. In the prevention of infectious diseases in large-scale livestock farming, it is very important to follow the rules of biosecurity.