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Biomedical subjects

K L Hughes

Publications and source records attributed to K L Hughes.

At least 19 recordsLinked to original sources

Treatment of opportunistic mycobacterial infections with enrofloxacin in cats.

Marked improvement was observed in the condition of 6 cats with opportunistic mycobacterial infections during treatment with enrofloxacin, a fluoroquinolone antibiotic. Complete remission was achieved in 3 cats after 3 to 7 weeks of treatment. The other 3 cats were euthanatized after 1 to 2 weeks of treatment for reasons not related to the treatment. Lesions did not recur within the follow-up period, which ranged from 9 to 16 months. Treatment of opportunistic mycobacterial infection in cats is complicated because many mycobacteria are resistant to antituberculosis drugs, which also can be toxic to cats, and because results of susceptibility testing with other antimicrobials do not always correlate with clinical response. Often, neither satisfactory nor long-term response is observed in cats treated surgically or with the antibiotics currently recommended. These findings suggested that enrofloxacin is effective in the treatment of infections caused by Mycobacterium smegmatis and M fortuitum var fortuitum in cats.

Animals

A clinical trial of a topical preparation of miconazole, polymyxin and prednisolone in the treatment of otitis externa in dogs.

A topical preparation containing miconazole, polymyxin and prednisolone was shown to be more effective in the treatment of otitis externa in 167 dogs than 2 other ear preparations containing antibiotics, an antimycotic and a corticosteroid. With miconazole, polymyxin and prednisolone, the recurrence rate was 26.7% compared with 72.6% and 54.3% when the other products were used. The mean duration of treatment required to achieve resolution of clinical signs was 9.6 days, compared with 12.2 days and 13.0 days and no cases failed to respond to treatment, compared with 17.7% and 14.3%. Malassezia canis alone (71%) or in association with bacteria (18%) was recovered from 44 of 49 ears cultured.

Administration, Topical

History of veterinary public health in Australasia.

The geographic isolation of Australasia has played a significant role in preventing the introduction of exotic diseases or in limiting the spread of many diseases which entered after settlement. Some infections such as psoroptic mange, tuberculosis and brucellosis became widely dispersed and some were ultimately to require novel methods to curtail them, e.g. greater use of rail and road transportation to convey stock, improved methods to locate and muster livestock in bush terrain (helicopters), improved diagnostic tests and the introduction of effective methods for tracing diseases found at abattoirs to the farms of origin. From the 1860s to the 1880s, there were such high mortalities from anthrax in Australia that a business syndicate associated with the Pasteur Institute established a laboratory in Sydney to produce anthrax vaccine from 1890 to 1898. The two-dose vaccine developed by Pasteur was unable to compete with a single dose spore vaccine later pioneered locally by Gunn and McGarvie-Smith. The most important achievements in veterinary public health in Australasia have been the successful eradication of brucellosis, the virtual eradication of hydatid disease in New Zealand and Tasmania, the substantial progress made in the eradication of tuberculosis from all but small regions of Australasia, and the development of a commercial vaccine to prevent Q fever in humans.

Animals

The ecology of Rhodococcus equi and physicochemical influences on growth.

Growth of Rhodococcus equi was studied in vitro. Optimal growth occurred under aerobic conditions between pH 7.0 and 8.5, at 30 degrees C. R. equi survived better in a neutral soil (pH 7.3) than it did in two acid soils (pH less than 5.5). It grew substantially better in soils enriched with faeces than in soils alone. Simple organic acids in horse dung, especially acetate and propionate, appear to be important in supporting growth of R. equi in the environment. The ecology of R. equi can be best explained by an environmental cycle allowing its proliferation in dung, influenced by management, grazing behaviour and prevailing climatic conditions. Preventive measures should be aimed at reducing or avoiding focal areas of faecal contamination in the environment.

Animals

Ecology of Rhodococcus equi.

A selective broth enrichment technique was used to study the distribution of Rhodococcus equi in soil and grazing animals. Rhodococcus equi was isolated from 54% of soils examined and from the gut contents, rectal faeces and dung of all grazing herbivorous species examined. Rhodococcus equi was not isolated from the faeces or dung of penned animals which did not have access to grazing. The isolation rate from dung was much higher than from other samples and this was found to be due to the ability of R. equi to multiply more readily in dung. Delayed hypersensitivity tests were carried out on horses, sheep and cattle, but only horses reacted significantly. The physiological characteristics of R. equi and the nature of its distribution in the environment suggested that R. equi is a soil organism.

Actinomycetales

Is Rhodococcus equi a soil organism?

A total of 189 isolates of Rhodococcus equi and related organisms and 16 marker strains representing the genera Rhodococcus and Corynebacterium were screened for 160 unit characters in a numerical taxonomic study. Analysis of the data indicated that R. equi forms a relatively homogeneous cluster distinctly separated from the recognized species of Rhodococcus and Corynebacterium (sensu stricto). Other members of the genus Rhodococcus are soil organisms and R. equi appears to fit into the genus on ecological as well as taxonomic grounds. It seems unlikely that R. equi could be a gastrointestinal tract commensal because unlike members of the latter group it is an obligate aerobe with an optimum temperature requirement of 28-30 degrees C. It is capable of utilizing simple organic compounds as sources of carbon or carbon and nitrogen and is sensitive to bile salts. Furthermore, it appears that isolation of R. equi from the gut contents of animals is dependent on those animals having access to grazing. Taxonomic studies (backed-up by ecological studies) support the concept that R. equi is a soil organism.

Actinomycetales

Contagious equine metritis in Australia.

Contagious equine metritis (CEM) was first diagnosed in Australia in August 1977 and it has since been found on 6 farms in 3 states, having been isolated from about 24 mares and 2 stallions. Details are given of the epidemiology and control procedures used to combat CEM on one farm. Difficulty was experience in successfully treating one infected stallion; this was thought to be associated with inadequate cleaning and treating of the diverticulum of the urethral fossa. Introduction of the disease has had far-reaching consequences and may well result in the adoption of routine bacteriological tests on stallions and mares of unknown or dubious breeding history and other measures to minimize the possibility of spread between farms.

Animals