013. Видання НаУКМА

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Browsing 013. Видання НаУКМА by Author "Avdeeva, Liliya"

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    Coinfection of avian pathogenic Escherichia coli and infectious bursal disease virus in broiler chickens
    (Національний університет "Києво-Могилянська академія", 2026) Nechypurenko, Oleksii; Furtat, Iryna; Dreval, Denis; Avdeeva, Liliya
    Infectious bursal disease virus (IBDV) is the main immunosuppressive agent in the poultry industry that stimulates the development of secondary bacterial infection. However, the avian pathogenic E. coli (APEC) could be a primary agent that induces the development of colibacillosis, nevertheless the absence of immunosuppression. The depletion of bursa after viral replication is crucial for starting bacterial dissemination because of devastation of systemic and local humoral immunity. Therefore, the aim of the work was to investigate the correlation between APEC and IBDV infection in broiler chickens. The bursal atrophy was observed from 21 days with further level depletion from 60 to 90% at the final stage of research. Moreover, APEC strains were isolated from birds at 28–42 days which is correlated with chronical immunosuppression. All E. coli isolates showed resistance to beta‑lactams (amoxicillin, amoxiclav), tetracyclines, and trimethoprim, highlighting the risk of multidrug‑resistant strains. There were no resistant strains to colistin and florfenicol. The IBDV strains were detected in the bursa of 21, 28 and 35 broilers with Ct level 22.8; 25.8; and 32.2 points, respectively that indicates decreasing the viral load. Based on partial nucleotide sequences of the VP2 gene, the pathogen was identified as very virulent United Kingdom 2019 strain. However, analysis of the samples from 42-day-old broilers revealed that the nucleotide sequence belonged to the vaccine strain. Therefore, coinfection of APEC and IBDV in broiler chickens enhances immunosuppression, creating conditions for secondary bacterial infections. The susceptibility to colibacillosis correlates with the stage of bursal depletion and may persist even during replication of the vaccine strain of IBDV after primary infection.
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    Colibacillosis in broiler chicks and its etiological link to the biological characteristics of Escherichia coli isolates from the breeder flock
    (2025) Nechypurenko, Oleksii; Furtat, Iryna; Dreval, Denis; Avdeeva, Liliya
    Pathogenic strains of Escherichia coli, capable of causing avian colibacillosis (APEC), currently pose a significant threat to modern poultry farming, in particular industrial broiler production. Moreover, the origin of colibacillosis in broiler chickens is connected with parental health issues. Therefore, the aim of the work was to investigate the etiological link between colibacillosis in 1-day old chicks and the biological characteristics of E. coli isolates from the breeder flock. A total of 65 pathogenic E. coli isolates were detected from broiler-breeders (n = 14) and 1-day-old chikens (n = 51). This shows a huge impact of collibacillosis on poultry farming at different levels of production. The main lesions were associated with fibrin deposition and omphlaitis formation. The last-mentioned parameter could affect the viability of chicks; nevertheless, the average Pasgar score was identified as 9.7 points. Amomg APEC, the most prevalent were O78 and O18 serotypes, wich were characterized by the absence of β-hemolysis. Moreover, the antibiotic profile of APEC isolated from parenteral and progeny flocks was similar. A high level of resistance to amoxicillin, amoxiclav, doxycycline, tetracycline, and enrofloxacin was found; more than 70% of isolated APEC were invulnerable to the mentioned antimicrobials. The most effective antibiotics were colistin, gentamicin, and florfenicol, to which only 0.0% and 2.0%, 14.3 and 9.8%, 7.1% and 2.0% of isolated APEC from broiler-breeders and chickens, respectively, were resistant. In addition, prolonged treatment of birds led to the formation of multi-resistant strains that affected chickens from the first days of life. Thus, studying the process of APEC infection through an integrated production chain can be useful for taking appropriate measures to prevent early cases of colibacilosis.