ANTIBIOGRAM PROFILING OF ISOGENIC IN VITRO-INDUCED VANCOMYCIN INTERMEDIATESUSCEPTIBLE AND PARENT SUSCEPTIBLE STAPHYLOCOCCUS AUREUS STRAINS

• Published in: Southeast Asian journal of tropical medicine and public health Vol. 50; no. 3; pp. 522 - 529
• Main Authors: Lulitanond, Aroonlug, Khamparat, Prapaipak, Srinan, Sasikan, Wongthong, Sujintana, Sinlapasorn, Siwaporn, Sirichoat, Auttawit, Tavichakorntrakool, Ratree, Chanawong, Aroonwadee
• Format: Journal Article
• Language: English
• Published: Bangkok Central Coordinating Board, SEAMEO-TROPMED Project 01.05.2019
• Subjects: Amoxicillin; Antibiotics; Antimicrobial agents; Cefuroxime; Dilution; Electrophoresis; Minimum inhibitory concentration; Oxacillin; Penicillin; Population studies; Staphylococcus aureus; Teicoplanin; Vancomycin
• ISSN: 0125-1562

Staphylococcus aureus with reduced vancomycin susceptibility has become of concern in clinical treatment of infections. The study examined antibiogram profiles of in vitro generated isogenic clinical vancomycin intermediate-susceptible S. aureus (VISA) strains (n = 40) and heterogeneous (with sub-populations of VISA) (hVISA) strains (n = 7) compared to their respective parent vancomycin-susceptible (VSSA) strains. The vancomycin susceptibility categories were classified according to their minimum inhibitory concentration (MIC) to vancomycin using an agar dilution method together with a population analysis profile/area under curve assay. Isogenic parent and descendent S. aureus pairs were verified by pulsed-field gel-electrophoresis amplicon size profiles. Using a disc diffusion assay and MIC measurement, 28% of VISA were shown to become more sensitive to 10/12 other antimicrobials tested, in particular against (> 2 dilutions) amoxicillin/clavulanate, cefuroxime, penicillin, and oxacillin, while 29% of hVISA were more susceptible, but at a lesser extent, to this set of antibiotics. Interestingly 3 hVISA and 11 VISA strains exhibited higher resistance to teicoplanin than their respective parent VSSA strains. This study indicates antibiogram profiles of clinical vancomycin less-sensitive S. aureus strains should lead to identification of alternative antibiotics and/or their combinations that could provide more successful treatment outcome.