Selective buffered charcoal-yeast extract medium for isolation of nocardiae from mixed cultures.

The recovery of Nocardia species from mixed cultures is facilitated by use of a selective medium. We show that buffered charcoal-yeast extract medium with polymyxin, anisomycin, and vancomycin can be used for the selective isolation of nocardiae from contaminated specimens.

Isolation of Clostridium spiroforme from rabbits.

The isolation of Clostridium spiroforme from intestinal contents of rabbits was achieved by sampling the supernatant-pellet interphase of centrifuged specimens processed for routine toxin analysis. High-speed centrifugation at 20,000x for 15 minutes provided a rapid and effective means of separating this anaerobic pathogen from the majority of both indigenous and non-indigenous intestinal microbial flora. The unusual helically-coiled, semicircular shape of the microorganism is considered, at least in part, responsible for this phenomenon.

A method for culturing the nasopharyngeal area of rabbits.

A method for obtaining antemortem nasopharyngeal cultures is described. Its usefulness for detecting the carrier state of Pasteurella multocida in clinically normal, apparently healthy nasal-culture-negative rabbits is also discussed.

Characterization of antigen purified from type 3 strains of Pasteurella multocida and its use for an enzyme-linked immunosorbent assay.

Surface antigens were purified from a type 3, 4 rabbit isolate of Pasteurella multocida designated as R11146. Two protein peaks were obtained by gel filtration with Sephadex G-200 from crude saline extract. Major antigenic activity was detected in the first peak. The first peak was absorbed onto DEAE-cellulose and eluted by a linear gradient of NaCl. Four fractions eluted from the column contained a single antigen which was identical to an antigen purified from another type 3 strain, P-1059. Also, they uniformly contained two protein species of molecular weights of 44,000 and 25,500. Six Pasteurella-free rabbits were infected intranasally with R11146 isolate and antibody response was determined by an enzyme-linked immunosorbent assay (ELISA) with the use of an antigen purified from P-1059 strain. Serum samples from the infected rabbits showed ELISA titers at the plateau stage by 21 or 28 days post-inoculation. Highest titers ranged from 1:15,000 to 1:16,000, while all the preinoculation sera had titers lower than 1:10. The high titers generally persisted for longer than 98 days after the infection. These results indicate that ELISA using a purified type 3 antigen is useful to detect P. multocida infection in rabbits by a type 3-related strain.

Serologic methods for detection of Pasteurella multocida infections in nasal culture negative rabbits.

An agar gel-diffusion test (AGDT) and an enzyme-linked immunosorbent assay (ELISA) were utilized to detect serum antibodies against Pasteurella multocida in naturally infected rabbits derived originally from a Pasteurella-free colony. The antigen used in both assays was purified from a serotype 3 (P-1059) strain of P. multocida. Among 47 serum samples tested 15 (32%) were seropositive; 12 (26%) of which were both AGDT and ELISA-positive, while 3 (6%) were ELISA-positive only. All rabbits examined were normal clinically and negative to repeated nasal cultures, but subsequent cultures at necropsy demonstrated the presence of P. multocida in 11 of the AGDT-positive rabbits and in 14 of the ELISA-positive rabbits. The organism was isolated most frequently from the naso-oropharynx and the tympanic bullae. Serotyping of isolates recovered from the nasopharynx were determined to be serotype 3 or 3,12. Ten seronegative rabbits also were necropsied and none were found harboring P. multocida. These preliminary data indicate that the application of an enzyme-linked immunosorbent assay may prove efficacious in identifying apparently healthy, consistently nasal culture-negative rabbits as subclinical carriers of P. multocida.

Enterotoxemia in rabbits.

The presence of Clostridium perfringens Type E iota toxin was confirmed from the cecal contents of 23 of 46 rabbits which died of enteritis complex. The most consistent lesions observed were hemorrhage and edema in the cecum. Rabbit toxicity tests showed the toxic cecal contents were lethal for young rabbits unless incubated with Clostridium perfringens Type E antiserum.

Myxomatosis in domestic rabbits in Oregon.

An epizootic of myxomatosis involved 26 rabbitries in western Oregon. Major clinical signs were inflammation and edema of the eyelids, conjunctiva, and anogenital area. Mortality ranged from 20 to 50%. On histologic examination, intracytoplasmic inclusion bodies were readily apparent in the epithelial cells of the conjunctiva. Lymphoid depletion of the spleen was also a common finding.