CLONAL DISSEMINATION AND COLONY MORPHOTYPE VARIATION OF VANCOMYCIN-RESISTANT ENTEROCOCCUS-FAECIUM ISOLATES IN METROPOLITAN DETROIT, MICHIGAN

Thirty-two isolates of vancomycin-resistant Enterococcus faecium (VRE) recovered from 25 patients hospitalized at six hospitals in the metro politan Detroit, Mich., area over a 32-month period were examined for relatedness by repetitive-sequence PCR (rep-PCR), All isolates were sh own to carry the vanA gene by PCR. The rep-PCR patterns generated from each isolate showed that the first three VRE isolates obtained from h ospital A between June 1992 and February 1994 were distinct strains. T hereafter, all VRE isolates originating from hospital A and those coll ected from five other area hospitals had identical rep-PCR patterns. O n detailed examination, subcultures of 25 of the 32 VRE isolates produ ced two distinct colony types characterized phenotypically by a rough and a smooth appearance, respectively, Both colony types retained the vanA locus and the rep-PCR pattern of the primary isolate. These data suggest that a single strain of VRE with the capacity to produce two c olonial variants has been disseminated to several Detroit-area hospita ls, The clinical significance of the colonial morphotypes is unclear.