ABSTRACT
A total of seven Staphylococcus intermedius cultures isolated from cases of canine pyoderma were investigated for the genetic basis of chloramphenicol resistance (Cmr). All of these S. intermedius isolates mediated Cmr via the expression of the Cm-inactivating enzyme chloramphenicol acetyltransferase (CAT); the respective cat genes were found to be located on small multicopy plasmids of 3.1 to 4.1 kb in four of the seven cultures. The four Cmr plasmids, designated pSCS20-23, differed upon restriction endonuclease mapping. Hybridization experiments identified all of them to belong to the pC221-family of staphylococcal Cmr plasmids. The expression of all four plasmid-encoded cat genes was inducible with chloramphenicol. The remaining three S. intermedius isolates also harboured an inducible cat gene of the pC221-type which, however, was found to be located in the chromosomal DNA. These differences in the subcellular localisation and consequently in the number of cat gene copies per S. intermedius cell had no influence on the MIC values of Cm exhibited by the respective S. intermedius isolates.
Subject(s)
Chloramphenicol Resistance/genetics , Dog Diseases/microbiology , Genes, Bacterial/genetics , Pyoderma/veterinary , Staphylococcus/genetics , Animals , Dogs , Microbial Sensitivity Tests/veterinary , Plasmids/analysis , Pyoderma/microbiology , Restriction MappingABSTRACT
A peat sequence on Gough Island, South Atlantic, is described. The deposit is at least 43 000 years old, and may be early Quaternary in age. Pollen analyses suggest a flora and vegetation on Cough Island similar to those of today, supporting conclusions based on pre-Holocene pollen samples from islands in the Tristan da Cunha group. The present flora has probably been on Cough Island continuously for at least the last 40000 years, and is not a Holocene immigrant flora.