Comparative pathomorphological, bacteriological and serological examination of broiler breeders and pheasants experimentally infected with Ornithobacterium rhinotracheale

The first isolation and detection of Ornithobacterium rhinotracheale from swollen head syndrome-infected broiler flocks in Iraq

Background and Aim:

The swollen head syndrome (SHS) makes up complex diseases that infect the upper respiratory tract in poultry and causes several economic losses. Furthermore, this syndrome is considered one of the multifactorial etiological agents. Therefore, this study isolated and molecularly detected Ornithobacterium rhinotracheale (ORT) in poultry.

Materials and Methods:

This study was conducted at 67 broiler farms that had birds observed to be infected with the SHS from September 2018 until August 2019. Subsequently, swabs were collected from their trachea, infraorbital sinuses, and lungs, after which obtained samples were treated through two methods: (a) The direct method, by uploading samples on FTA cards, and the indirect method using a transport media. Afterward, reverse transcription-polymerase chain reaction (RT-PCR) was used to analyze the directly treated samples; howeverAQ1, the culture method, followed by PCR, was used to analyze the indirectly treated samples. Next, a partial 16S RNA gene was isolated using four positive PCR products, after which the effect of 16 antibiotics was studied on the seven local ORT strains isolated.

Results:

The quantity of ORT isolated using the direct method was 28 (41.7%) samples, which were all positive for the strain. Identification was by direct molecular identification (RT-PCR) from samples loaded on FTA cards. Alternatively, 7 (10.4%) ORTs were detected from the indirect method, as obtained using the culture method and biochemical tests. Then, PCR was subsequently used to confirm the results. As observed, 784 bp bands were shown for all seven ORT isolates. Furthermore, results revealed a significant difference in the detection of ORT strains between direct and indirect methods, with p-value (<0.05) and standard deviation of the error±0.038 for the direct, then ±0.061 for the indirect method. For further analysis on the strain types, four 784 bp PCR products were taken, then partial 16S ribosomal sequence typing was conducted. All these four strains were found to be recorded in NCBI for the 1^st time as a local Iraqi strain, with accession numbers (MN931657, MN931656, MN931655, and MN931654). Notably, results also showed that all isolated strains were multidrug-resistant.

Conclusion:

From the results, ORT is proposed to be implicated as one of the etiological factors that cause SHSs in poultry. Phylogenetic analysis of the current ORT bacterial strains also showed that they are closely related to the Egyptian isolates.

An updated comprehensive review on ornithobacteriosis: A worldwide emerging avian respiratory disease

Ornithobacteriosis is an important emerging respiratory disease of domestic and wild birds caused by Ornithobacterium rhinotracheale (ORT) bacterium. The disease has been detected in some countries since 1980, which rapidly spread worldwide later on. Ornithobacteriosis can transmit either horizontally or even vertically. Infection with ORT is mainly characterized by respiratory distress, poor performance, acute death, and a drop in egg production. However, the most characteristic necropsy lesions of dead turkeys and chickens are yoghurt like airsacculitis and pneumonia, usually unilateral. Unfortunately, infection with ORT was misdiagnosed in most of the poultry flocks due to similarity with other respiratory pathogens and the lack of the ideal protocols for diagnosis. Recently, some molecular and serological techniques have been used to detect the infection. Treatment of ORT with antibiotics is very difficult and variable as a result of acquired resistance. Many vaccines have been developed to counteract such infection in broiler, layers, and breeder chicken and turkey flocks. Inactivated, live, and sub-unit vaccines have been used with satisfactory results. Thus, this review paper aimed to address ornithobacteriosis, emphasizing the distribution, transmission, clinical picture, diagnosis, and disease control.

Microscopic changes in the organs of broiler chickens with Ornithobacterium rhinotra-cheale infection

Nowadays ornithobacteriosis is widespread among industrial poultry in Ukraine and the world. The disease leads to significant economic losses. The large variation in the serotypes of the bacteria complicates the treatment of the disease. The study of microscopic changes that occur in organs during ornithobacteriosis will help to better understand the pathogenesis of the disease development. Ornithobacteriosis was diagnosed in clinically sick broiler chickens by bacteriological studies using Maldi Tof mass-spectrometry. As a result of the antibiotic sensitivity test, the pathogen was found to be sensitive to doxycycline, tilmicosin, rifampicin, cefazolin, amoxiclav and benzylpenicillin. Histological studies of internal organs – trachea, lungs, heart, kidneys, liver and spleen – were carried out. It was found that with spontaneous ornithobacteriosis of broiler chickens, the most expressive microscopic changes occur in the respiratory organs – the lungs and trachea and are characterized by a decrease in the lumen of the parabronchials due to edema of their walls and infiltration with lymphocytes, the absence of epithelium on the surface of the parabronchials, narrowing of the air capillaries of the parabronchial complexes, hemorrhages in the parenchyma of the parabronchial complexes, vasodilatation of the lung vessels and overflow of their blood vessels with blood cells, edema around the epithelium trachea, destruction of part of the tracheal mucosa epithelial cells, edema of its submucosa, expansion and overflow of blood vessels of the mucous membrane with blood cells. In the spleen there was a uniform diffuse edema of the parenchyma and a decrease in the number of lymphocytes in the lymphoid follicles; in the kidneys – expansion and overflow of the stroma blood vessels, uneven edema of the glomeruli of one part of the renal corpuscles and destruction of the glomeruli of another, granular degeneration of the convoluted and straight tubules of the kidneys; in the liver – edema, hemorrhage, violation of the hepatic lobules’ structure, expansion of the hepatic veins, granular degeneration of hepatocytes or their destruction; in the heart – edema of the myocardial interstitium, muscle fibers’ granular dystrophy, fragmentation of muscle fibers as a result of their rupture. Histological research of ORT infected chickens will lead to a better understanding the mechanism of pathological changes at the microscopic level, which will facilitate the development of more effective methods of treatment and prevention of the disease.

Comparison of the first Iranian native Ornithobacterium rhinotracheale vaccine with conventional vaccine: A challenge study

Background and Aim:

The best strategy to prevent or control an Ornithobacterium rhinotracheale (ORT) infection is vaccination. The present study aimed to compare the efficacy of the first Iranian inactivated ORT vaccine (Razi, Iran), which had been prepared from a native strain, with the Nobilis ORT Inac (Intervet, The Netherlands) through a challenge trial.

Materials and Methods:

Seventy-two 1-day-old specific pathogen-free White Leghorn chickens were used in this study. The birds were divided randomly into four groups. Following the vaccination and challenge of the birds, the efficacy of the Razi and the Intervet ORT vaccines was evaluated by serological, bacteriological, and molecular methods.

Results:

The antibody titer in vaccinated groups was determined to be significantly higher than unvaccinated birds. In addition, the difference in postmortem lesion scores between the vaccinated and unvaccinated birds was significant. The differences in the means of the antibody titers and postmortem lesion scores in birds that were vaccinated by the Razi and Intervet ORT vaccines were not significant.

Conclusion:

Considering the results of this study, it can be concluded that the Iranian native ORT vaccine was comparable to the Intervet vaccine. The Razi ORT vaccine has effectively decreased the duration of the ORT infection and can effectively protect the chickens against an ORT infection.

Ornithobacterium rhinotracheale: An Update Review about An Emerging Poultry Pathogen

Respiratory diseases in birds generate sanitary and economic impacts and may be related to the environment and climate. Mycoplasma gallisepticum, Ornithobacterium rhinotracheale (ORT), Pasteurella multocida, Avibacterium paragallinarum, Escherichia coli, Riemerella anatipestifer, and Bordetella avium are among the most important avian respiratory pathogens. ORT is responsible for causing ornitobacteriosis, a disease characterized by clinical signs ranging from mild to severe respiratory conditions, with high mortality rates, mainly affecting turkeys and chickens. The first report of ornitobacteriosis was in 1981 in Germany. Despite its importance, few studies on ORT have been published. In addition, the presence of this pathogen has been neglected in poultry farms, mainly due to the lack of appropriate diagnostic protocols. The lack of correct isolation and diagnostic protocols along with inappropriate use of antimicrobial agents have been contributing to treatment failure. Due to its economic importance to the poultry industry, ornitobacteriosis should be monitored and included in national programs for the prevention and control of avian respiratory diseases. This review aimed to update and discuss important issues related to ORT since this pathogen has great economic and sanitary implications for the chicken production chain.