Ornithobacterium rhinotracheale Isolated from Turkeys over a 20-Year Period Harbor Similar Antimicrobial Susceptibility Profiles and Multidrug Resistance.

Infections with Ornithobacterium rhinotracheale are causing respiratory diseases that require antibiotic treatment in poultry worldwide. In the field, this agent is known to often be resistant to many antimicrobials, complicating therapeutic interventions. Therefore, there is a clear need to monitor trends in resistance development. In the present study, antibiotic resistance profiles of 64 O. rhinotracheale strains isolated from diseased turkeys from 2002 to 2021 were investigated against 19 antimicrobial substances by the microdilution method. Susceptibility toward chloramphenicol, carbapenem, and sulfamethozaxole combination was found for all strains. Most isolates were also susceptible to penicillins (98%-100%), with the exception of oxacillin, cephalosporins (84%-100%), tetracycline (89%), and tylosin (88%). In the case of quinolones, 89% of isolates showed intermediate resistance to enrofloxacin, whereas 90% showed full resistance to nalidixic acid. Full resistance to the tested aminoglycosides and colistin was revealed for all strains. Eighteen different AMR profiles were elucidated; more than half of the isolates (53%) shared the same AMR profile. Similar susceptibility profiles of O. rhinotracheale isolates were found on the different farms, proving some stability over the years. All isolates were classified as multidrug resistant. Multiple outbreaks within a flock or in successive flocks within a farm comprised 46 O. rhinotracheale isolates. Here, occasional changes in susceptibility for some antimicrobial substances were observed. In general, most of the changes occurred in quinolones, followed by tetracycline switching mainly from intermediate resistance to full resistance and vice versa. The present surveillance provides actual data on effective antibiotic treatments in case of disease outbreaks and contributes to the One Health concept acknowledging the important link between animal and human health.

Los Ornithobacterium rhinotracheale aislados de pavos durante un período de 20 años albergan perfiles similares de susceptibilidad a los antimicrobianos y resistencia a múltiples fármacos. Las infecciones por Ornithobacterium rhinotracheale están causando enfermedades respiratorias que requieren tratamiento antibiótico en la avicultura en todo el mundo. En el campo, se sabe que este agente a menudo es resistente a muchos antimicrobianos, lo que complica las intervenciones terapéuticas. Por lo tanto, existe una clara necesidad de monitorear las tendencias en el desarrollo de resistencia. En el presente estudio, se investigaron los perfiles de resistencia a antibióticos de 64 cepas de O. rhinotracheale aisladas de pavos enfermos entre 2002 y 2021 frente a 19 sustancias antimicrobianas mediante el método de microdilución. Se encontró susceptibilidad a la combinación de cloranfenicol, carbapenem y sulfametozaxol para todas las cepas. La mayoría de los aislamientos también fueron susceptibles a las penicilinas (98 %­100 %), con la excepción de oxacilina, cefalosporinas (84 %­100 %), tetraciclina (89 %) y tilosina (88 %). En el caso de las quinolonas, el 89% de los aislados resultaron con susceptibilidad intermedia a la enrofloxacina, mientras que el 90% fueron resistentes al ácido nalidíxico. Todas las cepas revelaron resistencia a los aminoglucósidos y a la colistina probados. Se dilucidaron dieciocho perfiles diferentes de resistencia antimicrobiana; más de la mitad de los aislamientos (53%) compartían el mismo perfil antimicrobiano. Se encontraron perfiles de susceptibilidad similares de aislamientos de O. rhinotracheale en las diferentes granjas, lo que demuestra cierta estabilidad a lo largo de los años. Todos los aislamientos fueron clasificados como resistentes a múltiples fármacos. Los brotes múltiples dentro de una parvada o en parvadas sucesivas dentro de una granja comprendieron 46 aislamientos de O. rhinotracheale. Aquí, se observaron cambios ocasionales en la susceptibilidad a algunas sustancias antimicrobianas. En general, la mayoría de los cambios ocurrieron en las quinolonas, seguido por el cambio de tetraciclina principalmente de resistencia intermedia a resistente y viceversa. La vigilancia actual proporciona datos reales sobre tratamientos antibióticos efectivos en caso de brotes de enfermedades y contribuye al concepto de Una Salud que reconoce el vínculo importante entre la salud humana y animal.

Assessment of health and welfare of Austrian laying hens at slaughter demonstrates influence of husbandry system and season.

1. Selected health and welfare variables of laying hens from 79 flocks kept in alternative husbandry systems were assessed at the end of lay. 2. Investigations were carried out on 100 hens per flock at the slaughter line and recorded as part of a novel scoring system. In addition, post-mortem investigations as well as parasitological examinations were conducted on 10 birds from each flock. 3. Birds with access to free range had better plumage than birds kept in barn systems. Housing in aviaries was associated with a higher prevalence of foot pad lesions and keel bone deformations. In addition, poorer plumage, more and worse skin and foot pad lesions were documented in hens slaughtered during the winter months. 4. Oophoritis and/or salpingitis were the most prevalent pathomorphological changes observed. Intestinal parasites, especially Heterakis gallinarum and Ascaridia galli, were frequent. Hens kept indoors had fewer nematoda and cestoda than those from conventional and organic free range. 5. The slaughterhouse protocol allowed direct comparison of variables between flocks and specific problems to be identified in particular flocks. The results could be used to initiate detailed investigations into problematic issues on selected farms.

Clinical signs and progression of lesions in the gizzard are not influenced by inclusion of ground oats or whole wheat in the diet following experimental infection with pathogenic fowl adenovirus serotype 1.

In the present study the effects of dietary gizzard stimulation on the development and severity of adenoviral gizzard erosion were investigated. For this purpose, specific pathogen-free broilers were divided into six groups, investigating the influence of an oat-containing diet with higher fibre content, a whole wheat-containing diet and a control diet of nearly identical composition, but containing ground wheat. For each feed administered, one group of birds was experimentally infected on the 10th day of age by the oral route with virulent fowl adenovirus serotype 1 (FAdV-1), recently proven to induce gizzard erosions, while the respective negative control groups remained uninfected. Experimental feed was administered from 2 days post-infection onwards. No significant differences on gizzard health or in weight gain could be detected between uninfected control groups or between FAdV-1 infected groups that received different experimental feed. However, independent of the supplied diet, a significantly reduced weight gain was noted from 7 days post-infection onwards in FAdV-1 infected broilers compared to uninfected birds that received the same diet. Macroscopically, discolouration and erosion of the koilin layer and inflammation of the gizzard mucosa were observed in all FAdV-1 infected groups. Histologically, necrosis, degeneration of gizzard epithelial cells and multiple basophilic intranuclear inclusion bodies were observed. In summary, after experimental infection with FAdV-1 development of gizzard erosion in chickens was not influenced by the feeding regimes investigated. Therefore, it is unlikely that dietary gizzard stimulation influences the outcome of adenoviral gizzard erosion in vertically infected broilers.

Vaccination against histomonosis prevents a drop in egg production in layers following challenge.

The effect of attenuated Histomonas meleagridis on pullets was investigated and the protection of vaccinated adult laying hens against a severe challenge was studied in the same experimental setting. Four groups of 25 pullets were set up at 18 weeks of life and birds in two groups were vaccinated with in vitro-attenuated H. meleagridis. Chickens in two groups (vaccinated and non-vaccinated) were challenged 5 weeks later with virulent histomonads, while the remaining groups were retained until termination of the study 11 weeks post vaccination. Vaccination of pullets did not have any impact on their subsequent performance. Egg production of non-vaccinated but challenged birds dropped significantly (P ≤ 0.05) between 2 and 4 weeks post challenge (p.c.) to 58.7%, compared with 90% in control chickens. At 4 weeks p.c., the drop in egg production in vaccinated and challenged birds was significantly lower (P=0.02) than in non-protected layers. Pathological changes were found only in challenged birds 2 and 6 weeks p.c. Several non-vaccinated birds showed severe lesions in the caeca with sporadic involvement of the liver and atrophy of the reproductive tract. Vaccination prior to challenge reduced the incidence of pathological findings. For the first time, vaccination of pullets with in vitro-attenuated histomonads could be shown to be an effective and safe prophylactic tool to prevent a severe drop in egg production of commercial layers following experimental infection.

Seroprevalence of Histomonas meleagridis in pullets and laying hens determined by ELISA.

Serum samples from 1120 layers from 56 flocks and 400 pullets from 20 flocks were tested by an indirect sandwich ELISA to investigate the prevalence of antibodies to Histomonas meleagridis in chickens kept in alternative husbandry systems. The overall prevalence of antibodies to H meleagridis in layers was 37.3 per cent, and positive birds were identified in 50 flocks. This was significantly higher than in pullets, where only 8.3 per cent of the birds tested positive. Optical density (OD) values obtained from pullet sera were much lower than the OD values from layers; however, positive birds were detected in half of the pullet flocks. In particular, all birds from an organic pullet flock were found to be positive, with high OD values. Overall, the highest prevalence of positive sera was obtained from birds kept in free-range flocks. Attempts to reisolate live histomonads from birds in 18 layer flocks were unsuccessful.