On the basis of our calculations of the identification factors of VSEF and representative isolates of different VREF genogroups, we found that isolates of cluster l (n=4) resembled those of genogroup A, previously allocated to nonhospitalized patients and pig-derived VREF (Table 2).
The presence of the variant esp gene in VREF and VSEF was strongly associated with a specific epidemiologic source because the presence of esp is higher in clinical infections and epidemic-associated isolates than in surveillance isolates (Figure 2).
All isolated associated with nosocomial VREF-outbreaks but one were resistant to ampicillin, as were 81% and 65% of infectious isolates of VSEF and VREF, respectively.
The purK housekeeping gene was sequenced in 103 isolates: 64 VREF and 39 VSEF.
We showed that vancomycin-susceptible isolates clustered into three of these groups and that VSEF isolates from healthy persons also clustered distinctly from patient isolates.
Although the esp gene is virtually absent among community isolates, the presence of esp among VSEF and VREF from clinical infectious sites apparently unrelated to hospital outbreaks implies that this gene is not exclusively related to epidemic strains.