Comparison of ampicillin/sulbactam and amoxicillin/clavulanic acid for detection of borderline oxacillin-resistantStaphylococcus aureus

  • H. Liu
  • N. Lewis


Borderline oxacillin-resistantStaphylococcus aureus (BORSA) may be misidentified as intrinsically methicillin-resistantStaphylococcus aureus (MRSA) in the clinical laboratory. Under disk diffusion testing conditions designed to maximize detection of MRSA (incubation at 32 °C, pre-induction with methicillin, or plating on 4 % NaCl-supplemented agar), BORSA strains also tend to appear resistant to semisynthetic penicillins. Under these conditions, ampicillin/sulbactam appears to be more accurate than amoxicillin/clavulanic acid for differentiating BORSA from MRSA.


Internal Medicine Agar Penicillin Clinical Laboratory Disk Diffusion 
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  1. 1.
    Sabath LD Mechanisms of resistance to beta-lactam antibiotics in strains ofStaphylococcus aureus. Annals of Internal Medicine 1982, 97: 339–344.PubMedGoogle Scholar
  2. 2.
    Acar J, Courvalin P, Chabbert YA Methicillin-resistant staphylococcemia: bacteriological failure of treatment with cephalosporins. Antimicrobial Agents and Chemotherapy 1971, 1970: 280–285.Google Scholar
  3. 3.
    McDougal LK, Thornsberry C New recommendations for disk diffusion antimicrobial susceptibility tests for methicillin-resistant (heteroresistant) staphylococci. Journal of Clinical Microbiology 1984, 19: 482–488.PubMedGoogle Scholar
  4. 4.
    McDougal LK, Thornsberry C The role of beta-lactamase in staphylococcal resistance to penicillinase-resistant penicillins and cephalosporins. Journal of Clinical Microbiology 1986, 23: 832–839.PubMedGoogle Scholar
  5. 5.
    Liu H, Buescher G, Lewis N, Synder S, Jungkind D Detection of borderline oxacillin-resistantStaphylococcus aureus and differentiation from methicillin-resistant strains. European Journal of Clinical Microbiology and Infectious Diseases 1990, 9: 717–724.Google Scholar
  6. 6.
    Bush K Beta-lactamase inhibitors from laboratory to clinic. Clinical Microbiology Reviews 1988, 1: 109–123.PubMedGoogle Scholar
  7. 7.
    Bauer AW, Kirby WMM, Sherris JC, Turck M Antibiotic susceptibility testing by a standardized single disk method. American Journal of Clinical Pathology 1966, 45: 493–496.PubMedGoogle Scholar
  8. 8.
    National Committee for Clinical Laboratory Standards Performance standards for antimicrobial disk susceptibility tests. Approved standard M2-A3. NCCLS, Villanova, PA, 1984.Google Scholar
  9. 9.
    National Committee for Clinical Laboratory Standards Methods for dilution antimicrobial tests for bacteria that grow aerobically. Approved standard M7-A. NCCLS, Villanova, PA, 1985.Google Scholar
  10. 10.
    O'Callaghan CH, Morris A, Kirby SM, Shingler AH Novel method for detection of beta-lactamases by using a chromogenic cephalosporin substrate. Antimicrobial Agents and Chemotherapy 1972, 1: 283–288.PubMedGoogle Scholar
  11. 11.
    Neu HC Antimicrobial activity and human pharmacology of amoxicillin. Journal of Infectious Diseases 1984, 129, Supplement: 123–131.Google Scholar
  12. 12.
    Kobayashi S, Arai S, Hayashi S, Sakaguchi T In vitro effects of beta-lactams combined with beta-lactamase inhibitors against methicillin-resistantStaphylococcus aureus. Antimicrobial Agents and Chemotherapy 1989, 33: 331–335.PubMedGoogle Scholar
  13. 13.
    Aronoff S, Jacobs M, Johenning S, Yamabe S Comparative activities of the beta-lactamase inhibitors YTR 830, sodium clavulanate, and sulbactam combined with amoxicillin or ampicillin. Antimicrobial Agents and Chemotherapy 1984, 26: 580–582.PubMedGoogle Scholar
  14. 14.
    Fuchs PC, Barry AL, Thornsberry C, Gavan TL, Jones RN In vitro evaluation of Augmentin by broth microdilution and disk diffusion susceptibility testing: regression analysis, tentative interpretive criteria and quality control limits. Antimicrobial Agents and Chemotherapy 1983, 24: 31–38.PubMedGoogle Scholar
  15. 15.
    Tomasz A, Drugeon HB, De Lencastre HM, Jabes D, McDougall L, Bille J New mechanism for methicillin resistance inStaphylococcus aureus: Clinical isolates that lack the PBP 2a gene and contain normal penicillin-binding proteins with modified penicillin-binding capacity. Antimicrobial Agents and Chemotherapy 1989, 33: 832–839.Google Scholar

Copyright information

© Friedr. Vieweg & Sohn Verlagsgesellschaft mbH 1992

Authors and Affiliations

  • H. Liu
    • 1
  • N. Lewis
    • 1
  1. 1.Department of Medicine, Presbyterian Medical CenterUniversity of PennsylvaniaPhiladelphiaUSA

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