Potential for gene transfer among enterococci from a single patient and the possibility of confounding typing results

The results of typing methods used in a study of the epidemiology of enterococci in burn patients showed inconsistencies. The possibility that these inconsistencies were the result of gene acquisition or loss was investigated by using 12 isolates of Enterococcus faecalis from a single patient. In vivo and in vitro exchange and loss of genes were observed. The study showed that the typing results for isolates from this patient can be modified by known and demonstrated genetic elements; as a result, the isolates could be divided into between three and seven strains. In the present study, the SmaI digestion patterns gave the most consistent results, correctly identifying the transconjugants as indistinguishable from recipient strain 196R.