Joanna Kowalczyk

Introduction: Monitored EU-wide, mycoplasmosis is a significant poultry disease caused by bacteria of the genus Mycoplasma , among which M. gallisepticum, M. synoviae, M. meleagridis and M. iowae are of major importance. Infection can lead to clinical disease and economic losses. Serological assays can give false positive results because of antigenic cross-reactivity among Mycoplasma species. Molecular diagnostics provide greater specificity and reliability. This study investigated suspected cases of Mycoplasma meleagridis infection in turkeys and assessed whether the observed serological reactivity was by cross-reactive antibodies rather than a sign of M. meleagridis infection. Material and Methods: One case in a breeder turkey flock was investigated during the rearing period, and another case in a similar flock was explored in the laying period. Both flocks had serology results positive for M. meleagridis . The rearing flock was monitored with ELISA, PCR and sequencing for extended time after a single positive result, whereas the laying flock was testing using rapid plate agglutination (RPA) in addition because mortality was higher and egg production lower. In both cases, swab and blood samples were taken to verify the initial serological findings and assess the potential presence of M. meleagridis . Results: In the breeding flock, ELISA detected a single positive reaction against M. meleagridis in one of three houses. However, a PCR did not confirm the presence of M. meleagridis DNA, although Mycoplasma spp. DNA was detected at low/inconclusive levels. In the laying flock, the RPA test gave several seropositive reactions against M. meleagridis , whereas a PCR did not confirm its presence. Microbiological culture, 16S rRNA PCR and Sanger sequencing identified M. gallinarum in both flocks. Conclusion: The results highlight the limited specificity of serological assays and the necessity of molecular confirmation for accurate diagnosis.

Infectious bronchitis virus (IBV) is a highly infectious disease of chickens posing a major threat to poultry production worldwide. Due to genetic and antigenic variability, it is difficult to establish one universal protocol for vaccination against IB. The protectotype vaccination strategy, combining antigenically distinct vaccine strains, offers broader cross-protection than homologous IBV vaccination approaches. This field study aimed to establish serological baseline values in broiler chickens in a protectotype vaccination program using Avishield IB H-120 and Avishield IB GI-13, and to evaluate the program’s efficacy under field conditions on commercial farms where heterologous IBV genotypes were detected. The study was conducted on 25 broiler farms in 2023–2024. Day-old chicks were vaccinated via coarse spray. Blood samples were taken from them at six weeks of age and analyzed using IDEXX and BioChek ELISAs, and cecal tonsils were tested by real-time RT-PCR. Production performance was assessed using the European production efficiency factor (EPEF), with a cut-off value of 360. No IB-related clinical signs were reported, and the mean EPEF of the included farms was 408.7. The detected IBV genotypes were Mass + 793B, 793B, and 793B + VAR2. The presence of heterologous VAR2 did not negatively impact flock health or performance. Preliminary serological baseline values for vaccinated, non-VAR2 farms were established at 891–1332 (in chicks tested with the IDEXX ELISA) and 4193–5204 (in those tested with the BioChek assay). The H-120 + GI-13 program demonstrated high field efficacy, reliable serological profiles, and cross-protection in the presence of heterologous IBV. Continuous monitoring of IBV genotypes remains essential.

Respiratory diseases in poultry caused by Ornithobacterium rhinotracheale represent a significant challenge from both therapeutic and economic perspectives. Treatment of them, which uses antimicrobial agents, improperly contributes to the emergence and dissemination of multidrug-resistant strains within avian populations. The present study, based on O. rhinotracheale isolates (n = 733) obtained from the respiratory tract, joints, and organs of turkeys in Poland between 2016 and 2022, was conducted to assess the antimicrobial resistance of the strains and identify their serotypes. All O. rhinotracheale isolates were tested for antimicrobial susceptibility using the disk-diffusion method. The results of this study indicated that amoxicillin/clavulanic acid, doxycycline, florfenicol, and lincomycin/spectinomycin were the most effective agents against the isolates from turkeys. The findings showed that serotype I was the most prevalent among the tested turkey strains in Poland and was the serotype to which 29% of the O. rhinotracheale isolates affiliated.

Background: Infectious bursal disease (IBD) is a highly infectious disease of chicken found in all latitudes, due to the very high resistance to environmental conditions and commonly used disinfectants of the IBD virus (IBDV). Methods: This study was conducted to evaluate three IBD vaccination protocols in broiler chicken in terms of their effectiveness (clinical observations and production performance of the flock), estimation of serological baseline values (with the use of two different commercial ELISA kits) and the degree of progression of BF lesions (histopathological lesion score (HLS)) after vaccination. The three protocols were (I) single vaccination using an intermediate plus vaccine, (II) double vaccination with an intermediate vaccine and (III) double vaccination with an intermediate plus vaccine. Results: Birds on farms vaccinated with protocol II were characterized by the lowest antibody titers in both ELISA tests and the lowest average HLS. The highest IDEXX titers were obtained in birds vaccinated with protocol III, while in the BIOCHEK test the highest titers were obtained for birds vaccinated with protocol I. Protocols I and III were characterized by similar HLSs. Birds vaccinated with protocols I and III had higher immune uniformity. Conclusions: The estimated serological baseline values and the degree of HLSs presents a clear picture of the differences between the different vaccination protocols and allows their adaptation for different farms depending on the current IBD epidemiological situation.

Background: IBD is a highly infectious disease of chickens found in all latitudes, due to the very high IBDV resistance to environmental conditions and commonly used disinfectants. Methods: The study was conducted to evaluate 3 IBD vaccination protocols in broiler chickens, in terms of their effectiveness (clinical observations and production performance of the flock), estimation of serological baseline values (with the use of two different commercial ELISA kits), and the degree of progression of BF lesions (histopathological lesion score - HLS) after vaccination with: (I) single vaccination using intermediate plus vaccine; (II) double vaccination with intermediate vaccine; (III) double vaccination with intermediate plus vaccine. Results: Birds on farms vaccinated with protocol II were characterized by the lowest antibody titers in both ELISA tests, and the lowest average HLS. Highest IDEXX titers were obtained in birds vaccinated with protocol III, while in the BIOCHEK test the highest titers were obtained for birds vaccinated with protocol I. Protocols I and III were characterized by similar HLS. Birds vaccinated with protocols I and III had higher immune uniformity. Conclusions: The estimated serological baseline values and the degree of HLS presents a clear picture of differences between different vaccination protocols and allows their adaptation for different farms depending on the current IBD epidemiological situation.

One of the important problems in poultry production is bacterial infections and increasing resistance to antibiotics. The increasing incidence of multidrug-resistant bacteria is a major challenge for physicians and veterinarians and considerably limits treatment options. This study was undertaken in order to assess the prevalence and antibiotic resistance of Klebsiella spp. strains isolated from turkeys sampled from 2019 to 2022 in Poland. The material for study consisted of clinical samples taken during routine monitoring and microbiological identification testing at commercial poultry farms. From all 507 isolates of Klebsiella, 95% were identified by MALDI-TOF (Matrix-Assisted Laser Desorption - Ionisation-Time of Flight) as Klebsiella pneumonia, 2% were Klebsiella oxytoca, 2% Klebsiella variicola, or unidentified (1%). All isolated Klebsiella strains were tested for antimicrobial susceptibility by disk diffusion. The results of our study indicated that colistin, neomycin, florfenicol and amoxicillin/clavulanic acid were the most effective against the Klebsiella spp. isolated from turkeys. In addition, the results show a decrease in the number of multi-resistant Klebsiella spp. strains between 2019 and 2021.

Animal production is identified as one of the main sources of high concentrations of odours, which are related to air pollution, health problems of living organisms and indirect negative impact on production results. One common method for reducing emissions of ammonia is using preparations containing probiotics and hygroscopic or disinfecting compounds. This study was undertaken in order to determine the impact of innovative mineral–microbial deodorizing preparation, which reduces odorous gases, applying to the litter once a week in poultry houses on the physiological status of breeder chickens, broiler chickens and turkeys. Samples were collected after slaughter and analyzed using ELISA tests, flow cytometry and biochemical methods. Biochemical markers of the liver and kidney profile (ALT, AST, LDH, ALP, CK, TP, CALC, PHOS) and the titers of specific antibodies against AEV, aMPV, AAvV-1, IBDV, HEV, BA were analyzed in serum samples. The percentage contribution of T and B lymphocyte subpopulations was determined in the samples of tracheal mucosa, blood, and spleen. No significant differences were found between the control and experimental group with regard to all the analyzed parameters, with some exceptions for biochemistry. The results of our study indicated that mineral–microbial deodorizing preparation did not affect the physiological status of birds.

Colibacillosis is one of the major causes of economic losses in the poultry industry. Vaccination against E. coli is attracting increasing interest. The aim of the study was to evaluate the influence of vaccination with live, aroA gene-deleted vaccine on the structure and properties of field E. coli population and its potential impact on TRT vaccination efficacy in broiler chickens and turkeys. We performed three independent experiments on farms: (1) with antibiotic-free broiler chickens, (2) with conventional broiler chickens and (3) with broiler turkeys. In experiment 1, we have recorded an approx. 0–15% prevalence of multi-susceptible E. coli strains in the first production cycle. Starting from production cycle number two, after vaccination introduction, successive significant increases in E. coli susceptibility emerged, reaching 100% of strains at the end of production cycle 3. Increased E. coli susceptibility remained for three production cycles after vaccination withdrawal. In experiments 2 (2 production cycles) and 3 (1 production cycle), we recorded similar tendencies of E. coli susceptibility profile change. In experiments 1 and 2, the E. coli population count was lower after vaccination. In experiments 2 and 3, no negative influence of E. coli vaccination on the level of specific antibodies against TRT was recorded.