Polyclonal staphylococcal endocarditis caused by genetic variability

Cultures of blood obtained from a patient with Staphylococcus epidermidis p rosthetic valve endocarditis yielded 15 strains of S, epidermidis, Genome m acrorestriction and amplified fragment-length polymorphism analyses of thes e strains showed that they belonged to 4 different, very closely related cl ones, suggesting that they were the result of genetic variability of an inf ecting strain during the infectious episode. In vivo experiments in a rat m odel for foreign body infections using 1 of the S, epidermidis strains from the patient showed genetic variability similar to that of the infecting st rain. In the rat model, we also detected the simultaneous presence of diffe rent clones that were identical to those isolated from our patient, thus co nfirming the possibility of genetic variability, It is important to note th at the 4 clones isolated from our patient presented with 2 different antibi ograms. Therefore, in cases of foreign device-related infections due to coa gulase-negative staphylococci, the possibility of polyclonal infection has to be taken into account, particularly as regards differences in antibiotic susceptibility.