IS6770, AN ENTEROCOCCAL INSERTION-LIKE SEQUENCE USEFUL FOR DETERMINING THE CLONAL RELATIONSHIP OF CLINICAL ENTEROCOCCAL ISOLATES

Enterococci expressing resistance to antimicrobial agents are increasi ngly important nosocomial pathogens. Effective strategies to prevent o r abort outbreaks of resistant enterococcal infection will rely on an accurate understanding of the mechanisms by which these organisms spre ad. A 1065-bp insertion-like sequence (IS6770) is present in varying c opy numbers in >90% of enterococcal strains thus far examined, Hybridi zation patterns resulting from hybridization of enterococcal genomic D NA with an internal IS6770 probe vary considerably between unrelated s trains and correlate well with results of pulsed-field gel electrophor esis and field-inversion gel electrophoresis in identifying clonal rel ationships among enterococcal isolates. IS6770 analysis of several out breaks of resistant enterococci has confirmed the spread of single res istant clones rather than the emergence of resistance within the resid ent flora. These results suggest that IS6770 hybridization will be a u seful tool for tracing the epidemiology of nosocomial enterococcal inf ections.