Vaccination trials against Mycoplasma mycoides subsp. mycoides (large-colony-type) infection in goats.

Vaccination trials against Mycoplasma mycoides subsp. mycoides in suckling and weaned kids are described. A formalin-killed vaccine with adjuvant was used. Challenge to the vaccinated suckling kids was by ingestion of dam's infected milk and by subcutaneous inoculation of 10(6) organisms, and to the vaccinated weaned kids, by subcutaneous inoculation alone. The weaned 6-week-old kids were vaccinated, given a booster 3 weeks later and challenged 1 month after that. Serological monitoring was by enzyme-linked-immunosorbent assay (ELISA). The six control kids remained serologically negative and after challenge were pyrexic and mycoplasmaemic. All died or were killed in extremis, with a characteristic cellulitis at the site of inoculation, arthritis and swollen spleen. In contrast, the vaccinated kids remained healthy. There was a modest antibody response to the initial vaccination and a further steep rise after the booster. After challenge the organism was recovered only from the lymph nodes proximal to the site of challenge in some animals, and from the liver and kidney in two animals. All the vaccinated suckling kids were unaffected by ingestion of their dam's infected milk. The kids that received only one vaccine inoculation on the day of birth, and one control kid, succumbed to subcutaneous challenge, whereas the kids that were given a booster, except for one, remained healthy.

Clinical pharmacology of tiamulin in ruminants.

Median values for the minimum inhibitory concentrations (MIC) of tiamulin for Mycoplasma and Acholeplasma isolated from ruminants were 0.05 micrograms/ml and 0.025 micrograms/ml, respectively. These values were close to the MIC values of tylosin and considerably lower than the respective values for spectinomycin, Spiramycin and oxytetracycline. The serum concentration--time profile of tiamulin after intramuscular (i.m.) injection to goats, ewes, cows and calves, and after oral administration to preruminant calves was characterized by a rapid absorption phase (absorption t1/2 of less than 30 min.), a short plateau phase, an elimination t1/2 ranging between 3 and 6 h, and low peak serum drug levels. The serum elimination t1/2 of the drug after intravenous (i.v.) injection was 25 min. It appears that tiamulin is extensively metabolized in ruminants and is well distributed throughout the body. Drug concentrations in the lungs, liver, and the kidneys 1 h after i.v. injection were four to seven times higher than in blood. The drug penetrated very rapidly into the milk after i.m. administration; mean peak drug concentrations in normal milk and in milk secreted from inflamed glands of cows were 7.5 times and 1.2 times higher respectively, than the mean peak serum drug concentrations. Concentrations of tiamulin of potential therapeutic value in the treatment of mycoplasmal infections can be maintained in the lungs for at least 12 h after i.m. injection at 10 mg/kg, and in preruminant calves after an oral dose of 20 mg/kg. However, tiamulin possesses several very serious side-effects and the i.v. route of administration is definitely contraindicated.

Observations on Mycoplasma mycoides subsp. mycoides infection in Saanen goats.

An epizootic in white Saanen goats, caused by Mycoplasma mycoides subsp. mycoides is described. Twenty-five flocks totalling approximately 4,500 animals were involved. The disease was characterized by a high, transient temperature, general malaise and mastitis in the lactating does, and a keratoconjunctivitis, arthritis, mycoplasmaemia and death among the kids. In one goat flock there was a precipitous change in the character of the disease, from a predominantly mastitis syndrome to a fulminating pleuropneumonia. In another goat flock, twin kids were born with an advanced purulent, proliferative arthritis, suggesting early congenital infection. In yet another infected flock there were cases of subcutaneous abscesses from which both M. mycoides and Corynebacterium pyogenes were cultured. M. mycoides was also isolated from synovial fluid and the parenchymal organs of an Ibex mountain goat that died of a purulent polyarthritis. Experimental infection in kids caused a diffuse cellulitis at the site of inoculation, a high fever, polyarthritis and death.