title: Clinical isolates of Staphylococcus aureus from 1987 and 1989 demonstrating heterogeneous resistance to vancomycin and teicoplanin.
abstract: Fifty isolates of Staphylococcus aureus, obtained during a multicenter clinical trial evaluating the efficacy of teicoplanin that was performed between 1987 and 1992, underwent glycopeptide susceptibility testing, and 2 isolates were found to be capable of growth on agar containing 4 or 8 mg/L of vancomycin. Both of these isolates were from patients that had received prolonged teicoplanin therapy and were deemed clinical failures. Extended susceptibility testing combined with mecA gene probing revealed that one isolate was susceptible to oxacillin, the other was resistant, and both were susceptible to a variety of nonglycopeptide agents. Population analyses revealed heterogeneous vancomycin- and teicoplanin-susceptibility profiles. Both strains were differentiated from recent glycopeptide intermediately resistant Staphylococcus aureus isolates by pulse-field analysis and by the fact that the resistance phenotype was stable to multiple serial passages. To our knowledge, this is the earliest report of S. aureus clinical isolates having reduced vancomycin and teicoplanin susceptibility.
authors.affiliation: Anti-infective Research Laboratory, Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA. m.rybak@wayne.edu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rybak
authors.forename: Raymond
authors.initials: R
authors.lastname: Cha
authors.forename: Chrissy M
authors.initials: CM
authors.lastname: Cheung
authors.forename: Venkata G
authors.initials: VG
authors.lastname: Meka
authors.forename: Glenn W
authors.initials: GW
authors.lastname: Kaatz
mesh_terms: D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D015169:Colony Count, Microbial; D004269:DNA, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods; D011336:Probability; D012189:Retrospective Studies; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D017334:Teicoplanin / Q000494:pharmacology*; D020713:Vancomycin Resistance
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D017334:Teicoplanin