The term glycopeptide refers to a group of antimicrobial agents that includes vancomycin, teicoplanin, and several other drugs currently in U.S. clinical trials. Severely limited treatment options . All clinical GISA isolates have been recovered from patients who apparently failed vancomycin therapy. Because vancomycin is the usual agent used to treat MRSA infections, the decreased susceptibility of GISA isolates to this drug limits therapeutic options to fewer drugs.
Detection can be difficult .
Like MRSA, GISA may show heteroresistance. Not all routine susceptibility testing methods can detect GISA isolates. In general, MicroScan conventional panels and Etest can detect staphylococci with decreased susceptibility to vancomycin when the tests are incubated for a full 24 hours before reading. The prevalence of GISA is generally unknown. One way to find out if GISA isolates exist in a health care facility is to screen for them.