Use of multilocus enzyme electrophoresis to distinguish clinically important strains of Staphylococcus intermedius from the skin of dogs

Aims To use multilocus enzyme electrophoresis to determine the genetic structure of Staphylococcus intermedius from normal skin of dogs and those isolated from a variety of disease conditions and to distinguish clinically important strains in dogs. Methodology The diversity amongst 129 isolates of S intermedius from the skin and mucosa of 32 healthy dogs and 120 isolates from diseased sites in 120 individual dogs was examined using multilocus enzyme electrophoresis. Associations among ETs were examined to determine the diversity of isolates. Results Twenty two ETs were distinguished comprising 21 containing isolates from diseased sites and 11 containing isolates from normal dogs. The majority of isolates (171 of 249; 69%) were located in two ETs (ET 1 and ET 4), that were not distinguishable phenotypically. ET 1 contained 94 isolates (54 isolates from healthy dogs and 40 isolates from diseased sites) and ET 4 contained 77 isolates (46 from healthy dogs and 31 isolates from diseased sites). Further, 77.5% of isolates from healthy dogs were present in ET 1 and ET 4 and 59% of isolates from diseased dogs belonged to the same two ETs. There was only a small difference in genetic diversity among isolates taken from healthy dogs (11 ETs H = 0.182) and those isolates taken from clinical specimens from diseased dogs (21 ETs; H = 0.218). Of the 21 ETs from diseased sites, ET 16 contained all six isolates from Staphylococcal Scalded Skin Greyhounds. Conclusions The small difference in genetic diversity between isolates from the skin and mucosa of healthy dogs and isolates from various diseases, as well as the presence of the majority of isolates in two ETs, is consistent with the role of S intemedius as an opportunistic pathogen. The confinement of all Staphylococcal Scalded Skin Syndrome isolates within one ET is confirmation of this entity as a distinct disease of dogs.