Alberto Back

Ornithobacterium rhinotracheale Infection in Turkeys: Experimental Reproduction of the Disease

This report details the first experimental production of clinical disease, mortality, and pathology resembling that of field infections by using Ornithobacterium rhinotracheale alone. Twenty-two-week-old male turkeys were exposed to O. rhinotracheale or lung homogenate from O. rhinotracheale-infected turkeys. Within 24 hr after inoculation, turkeys given O. rhinotracheale or lung homogenate intratracheally were depressed and coughing and had decreased feed intake. By 48 hr, several birds were coughing blood and ultimately died. Grossly, the lungs were reddened, wet, and heavy, failed to collapse, and were covered by tenacious tan-to-white exudate. Microscopically, the parabronchi and air capillaries were filled with fibrin, heterophils, macrophages, and small numbers of gram-negative bacteria. The pleura was often covered by a thick layer of fibrin, heterophils, and macrophages. Turkeys that survived to day 7 postinoculation had severe, subacute pneumonia. Ornithobacterium rhinotracheale was recovered from the lungs of most birds with pneumonia and was also cultured from the air sacs, sinuses, tracheas, spleens, and livers. All turkeys inoculated with O. rhinotracheale developed antibodies to O. rhinotracheale detectable by the serum plate agglutination test.

Isolation and identification of Ornithobacterium rhinotracheale from commercial turkey flocks in the upper midwest

Increased death loss was seen in a flock of 22-wk-old tom turkeys. The predominant postmortem lesion was fibrinopurulent pneumonia and pleuritis. Within 5 wk, turkey flocks on 17 other farms developed similar problems. All affected flocks during the 5-wk period were between 14 and 22 wk of age, and the severity of clinical signs and the degree of mortality increased with age. Ornithobacterium rhinotracheale was isolated in pure culture from affected lungs. Further investigation by tracheal swab culture of 261 flocks between 5 and 7 wk of age resulted in detection of O. rhinotracheale in 43% of the flocks.

Tissue distribution of Ornithobacterium rhinotracheale in experimentally infected turkeys

lysis of the ramus and body of the mandible. There was destruction of alveolar bone with displacement of caudal cheek teeth and amorphous periosteal reaction on the ventral margin of the left mandibular body (Fig la). Differential diagnoses included lymphosarcoma, odontoma, ameloblastic odontoma, caseous lymphadenitis and actinomycosis. Cytological examination of the tumour and submandibular lymph node tissue taken by fine needle aspiration biopsy revealed

Outer membrane proteins for serologic detection of Ornithobacterium rhinotracheale infection in Turkeys

Ornithobacterium rhinotracheale (ORT) is a bacterium responsible for a respiratory disease in turkeys and chickens and has been identified as one of the emerging respiratory bacterial pathogens. The clinical signs and lesions caused by ORT are very similar to those caused by other respiratory infectious agents; therefore, an accurate diagnostic test is necessary to identify the infection. In this study, we have investigated the use of outer membrane proteins of ORT in an indirect enzyme-linked immunosorbent assay (ELISA) to detect the exposure to ORT infection. Outer membrane proteins of ORT were extracted and used as an antigen in ELISA to detect infection in turkeys exposed to different serotypes of ORT. The ELISA results were compared with the conventional serum plate agglutination test. The agglutination test detected specific antibodies for ORT in 65% of experimentally infected turkeys during the first 2 wk of infection. The ELISA detected up to 100% of infected birds for 8 wk postinfection. The results suggest that ELISA is able to detect the exposure to ORT in later stages of the infection and this assay can be used in serologic surveillance of ORT infection for poultry in the field.

A temporal study of Salmonella enterica serotypes from broiler farms in Brazil

The present study analyzes the characteristics of Salmonella spp. from broiler chicken farms in Brazil. In total, 82 Salmonella spp. strains were characterized by serotyping, determining susceptibility to antimicrobials, and using pulsed-field gel electrophoresis (PFGE). Fifteen Salmonella serotypes were identified, among which Minnesota (40.24%), Infantis (14.63%), Heidelberg (7.31%), Senftenberg (6.09%), and Mbandaka (6.09%) were the most frequent. Salmonella Minnesota occurred mostly in the state of Mato Grosso do Sul and in one of the broiler companies surveyed. Approximately 60% of the strains were resistant to at least one of the antimicrobials tested. From these isolates, 17.07% were resistant to only one antimicrobial (tetracycline or streptomycin), and 9.75% were resistant to 3 or more antimicrobial classes. Thirteen resistance profiles were characterized, the most frequent of which were the resistance to tetracycline (15.85%); to the combination of trimethroprim with sulfamethoxazole, and tetracycline (10.97%); and to the combination of streptomycin and tetracycline (9.75%). Multiple correspondence analysis revealed that susceptibility or resistance of the analyzed strains and also particular Salmonella serotypes were associated with broiler-producing companies where the samples were collected. Strains presented high intraserotype genetic variability, as shown by the 64 PFGE profiles, suggesting the existence of several contamination sources in the surveyed farms.

Natural infection of turkeys by infectious laryngotracheitis virus

The infectious laryngotracheitis virus (ILTV) is an important respiratory pathogen of chickens that also infects pheasants and peafowl. Epidemiologically non-related commercial turkey flocks with clinical signs such as tracheitis, swollen sinuses, conjunctivitis and expectoration of bloody mucus were examined for the presence of the virus. Laboratory ILTV detection was performed by virus isolation in embryonated eggs and cell cultures, PCR and sequencing of amplification products, histopathology, indirect immunofluorescence and electron microscopy. One ILTV turkey isolate was also experimentally inoculated into susceptible chickens and turkeys, reproducing a mild respiratory disease. This is the first description of natural infections with ILTV in turkeys.

Susceptibility of Broiler Chicks to Infection by Avian Pneumovirus of Turkey Origin

In this paper we present the results of studies on the infectivity of an isolate of avian pneumovirus (APV) from turkeys to broiler chickens. Two-week-old broiler chicks free of antibodies to APV were exposed either by oculonasal or oral route with a cell cultured APV of turkey origin. Chickens from both APV-inoculated groups exhibited clinical signs that included coughing, sneezing, nasal discharge, and watery eyes during 2-8 days postinoculation. Tissue samples from birds in the APV-inoculated group were positive for APV by polymerase chain reaction (PCR) up to 9 days postinoculation. Samples of blood from both oculonasally and orally infected chickens were positive for APV. Intestinal samples from chickens infected with APV orally were positive for the presence of APV on PCR up to 9 days postinoculation. APV was reisolated from samples taken from chickens in both groups inoculated orally and oculonasally. Sera from birds exposed by the oculonasal or by the oral route showed the presence of APV-specific antibodies.

Prevalence of antibodies against Ornithobacterium rhinotracheale in broilers and breeders in Southern Brazil.

Abstract In this investigation, we determined the prevalence of the Ornithobacterium rhinotracheale (ORT) infection in broilers and broiler breeders in southern Brazil. We also correlated the presence of antibodies in broilers with performance. Sera from 1550 broilers from 50 flocks were collected during the slaughter time in nine companies with federal veterinary inspection of the state of Rio Grande do Sul. Sera from 480 meat-type breeders of 40 flocks from 14 companies in southern Brazil were also analyzed by enzyme-linked immunosorbent assay, and the prevalence of antibodies was determined. The prevalence of ORT antibodies in broiler flocks was 63.83%, but in each individual flock only 6.52% of the birds were positive. The prevalence in broiler breeder flocks was 100.00%, and in each individual flock 94.62% of the birds were positive. There was a positive correlation between the presence of antibodies to ORT and decreased body weight in broilers. There was no significant correlation between presence of antibodies to ORT and age, lineage, efficiency index, feed conversion, and mortality. There was a positive correlation between the presence of respiratory signs and antibodies to ORT, although the reverse correlation was not significant. These results confirm that ORT is present and widespread in broilers and broiler breeders in southern Brazil.

SERE, a widely dispersed bacterial repetitive DNA element

The presence of a Salmonella serotype Enteritidis repeat element (SERE) located within the upstream regulatory region of the sefABCD operon encoding fimbrial proteins is reported. DNA dot-blot hybridisation analyses and computerised searches of genetic databases indicate that SERE is well conserved and widely distributed throughout the bacterial and archaeal kingdoms. A SERE-based polymerase chain reaction (SERE-PCR) assay was developed to fingerprint 54 isolates of Enteritidis representing nine distinct phage types and 54 isolates of other Salmonella serotypes. SERE-PCR identified five distinct fingerprint profiles among the 54 Enteritidis isolates; no correlation between phage types and SERE-PCR fingerprint patterns was noticed. SERE-PCR was reproducible, rapid and easy to perform. The results of this investigation suggest that the limited heterogeneity of SERE-PCR fingerprint patterns can be utilised to develop serotype- and serogroup-specific fingerprint patterns for isolates of Enteritidis.

Development, Characterization, and Preliminary Evaluation of a Temperature-Sensitive Mutant of Ornithobacterium rhinotracheale for Potential Use as a Live Vaccine in Turkeys

SUMMARY. A temperature-sensitive (Ts) mutant strain of Ornithobacterium rhinotracheale (ORT) was developed after exposure of the wild-type organism to N-methyl-N′-nitro-N-nitrosoguanidine. The Ts mutant strain grew at 31 C but had its growth inhibited at 41 C unlike wild-type parent strain. The Ts mutant and parent strains were characterized. Morphologic and biochemical properties of wild-type and mutant strains did not show any differences. The strains were also characterized by polymerase chain reaction (PCR)-based fingerprinting methods. Results showed similar patterns in repetitive sequences by repetitive PCR (enterobacterial repetitive intergenic consensus, highly conserved repeated DNA elements present in Streptococcus pneumoniae (BOX), repetitive extragenic palindromic, and Salmonella enteritidis repetitive element primers); however, random amplified polymorphic DNA fingerprinting was able to differentiate mutant and parent strains showing a unique pattern for each of the ORT strains. The rationale for the use of a Ts strain as a vaccine is based on the ability of the mutant to colonize the upper respiratory tract but not the lower respiratory tract and systemic system of the birds, where the wild-type strain causes severe lesions. In a preliminary evaluation, Ts strain of ORT was recovered from tracheas and choanae of Ts-treated turkeys for 13 days postadministration of the strain either in drinking water or by oculonasal instillation. Humoral immune response was detected in Ts-vaccinated but not in control group birds after 3 wk postadministration. Results suggest that Ts strain of ORT has promising potential use as a live vaccine for ORT.