Conjugation of antibiotic resistance in Streptococcus suis.

Forty-eight clinical isolates of Streptococcus suis were examined for antibiotic sensitivity and the presence of plasmid DNA. It was determined that isolates from this study showed a substantial increase in resistance to erythromycin (ery), clindamycin, and tetracycline (tet) compared to a similar study conducted five years earlier. Eleven of the 48 isolates contained plasmid DNA as revealed by DNA isolation and gel electrophoresis. Plasmid DNA from four strains resistant to the above three antibiotics was tested for the ability to transform an antibiotic sensitive recipient. No transformation of antibiotic resistance could be demonstrated. In other experiments, the above four strains, along with four plasmid-negative triply resistant strains were tested for the ability to transfer tet or ery resistance to tet and ery sensitive recipients by conjugation. In each mating, antibiotic resistance was transferred at frequencies averaging 2.4 x 10(-6) recombinants/recipient for ery and 3.4 x 10(-6) recombinants/recipient for tet resistance. DNA from each clinical specimen, as well as the recombinants mentioned above was probed with tn916. Autoradiographs revealed that several clinical isolates and recombinants bound the probe. It is concluded that conjugation of antibiotic resistance in these clinical strains is possibly mediated by a transposon similar to tn916.

Association of a Pasteurella haemolytica-like organism with enteritis in swine.

A Pasteurella haemolytica-like organism was isolated from the intestines of 28 swine with clinical, gross, or microscopic evidence of enteritis. In 15 cases, other known enteric pathogens were also demonstrated, and in 13 cases, no other pathogens were detected. The mean age of affected animals was 44 days. Most of the animals had clinical evidence of diarrhea. Gross enteric lesions were present in 17 of 21 cases. Microscopic lesions were present in 24 of 26 cases. A diffuse or segmental moderate to severe necrotizing enteritis was the most common lesion in cases in which only the Pasteurella haemolytica-like organism was isolated. Biochemical tests gave results consistent with Pasteurella haemolytica, and 5 of 15 isolates met criteria for biotype A. Negative results were found with an indirect haemagglutination procedure for P. haemolytica.

Efficacy of a live Pasteurella multocida vaccine for the prevention of experimentally induced bovine pneumonic pasteurellosis.

Seventeen Holstein-Friesian calves weighing an average of 139.8 +/- 13.5 (mean +/- standard deviation) kg were used in a study to determine the efficacy of a live vaccine containing of Pasteurella multocida A:3 and Pasteurella haemolytica A:1. Eleven calves received the vaccine by intramuscular injection in the right shoulder, whereas six calves received vaccine diluent and served as non-vaccinated controls. Fourteen days following vaccination (Day 15) all calves were inoculated deep intranasally with 3.6 X 10(7) TCID50 bovine herpes virus-1. On Day 16, calves were stressed by transports, and on Day 17 calves were challenged intratracheally with P. multocida A:3. On Day 22 calves were euthanized and necropsied, and tissues were collected for pathological and microbiological evaluations. Scores were assigned to each calf based on the severity of observed clinical signs. Macroscopic lung lesions were expressed as percentage of tissue involved relative to the total lung tissue of a calf. Plasma fibrinogen concentration, rectal temperature, serum antibody level, microscopic appearance of lung, and microbiologic results were also recorded for analyses. The control calves had significantly higher clinical-sign scores (P less than 0.05) and more severe gross lesions (P less than 0.05) than the vaccinated calves. Although the vaccinated calves had a slight increase of immunoglobulins M and G classes, the differences were not statistically significant (P greater than 0.05, P greater than 0.05). The results of the study indicate that the live Pasteurella vaccine is effective against experimental P. multocida infection in calves.

Brucella suis biovar 3 infection in a Kentucky swine herd.

Sows from a large farrow-to-finish operation in western Kentucky had late-term abortions. Boars and breeding-age sows were tested serologically for brucellosis, and 83 of 125 were classified as reactors. No brucellae were isolated from the tissues of 6 unbred reactor sows, but Brucella suis biovar 3 was recovered from 5 aborted fetuses. Epidemiological studies failed to determine the source of the infection.

Isolation of Actinobacillus suis from a Canada goose (Branta canadensis).

Blindness from conjunctivitis caused by Actinobacillus suis was found in a Canada goose (Branta canadensis) from a wildlife refuge in Kentucky. Lesions were not observed elsewhere and other body organs were grossly normal. Actinobacillus spp. in birds is rare and this is apparently the first report of conjunctivitis resulting from this infection in waterfowl.

Isolation and identification of yeasts and yeastlike organisms from clinical veterinary sources.

A total of 229 isolates of yeasts and yeastlike organisms recovered from a variety of clinical specimens were identified by using the API 20C microsystem in conjunction with morphological characteristics and urea hydrolysis. Of the 229, 218 (95.1%) were from bovine, porcine, canine, and equine species and the remaining 11 (4.9%) were from feline and avian species. The gastrointestinal and reproductive tracts were the major sources of yeasts and yeastlike organisms, representing 60 (26.2%) and 28 (12.2%) isolates, respectively.

An acid phosphatase activity in isolates of Bordetella bronchiseptica.

A simple qualitative test was used to investigate acid phosphatase activity in isolates of Bordetella bronchiseptica from different animal species. Of the 78 isolates examined, 58 showed the enzyme activity in less than 12 hours of incubation at 37 degrees C.

Identification of Staphylococcus hyicus with the API staph strip.

The API Staph Strip system (API System S.A., Montalïeu-Vercieu, France) was compared with conventional methods for identification of Staphylococcus hyicus isolated from cases of exudative epidermitis in swine. The API Staph Strip was found to provide unique profile numbers, namely, 6-514-151, 6-514-153, and 6-516-153. These profile numbers are not listed in the API Staph Strip data base. It was found that the use of this miniaturized system is preferable to conventional methods for the identification of the causal agent of swine exudative epidermitis.

Lancefield group R streptococci associated with pneumonia in swine.

During a 12-month survey of streptococcal infections in swine, 14 of 98 isolates were found to belong to Lancefield group R. Most of these isolates were from pigs with pneumonia. Approximately half the group R isolates were associated with concurrent Pasteurella pneumonia.