Susceptibility testing of Streptococcus pneumoniae and Viridans streptococcal isolates against: quinolones, oxazolidinones and glycopeptides.

UNLABELLED: The aim of this study was to test the susceptibility of 100 strains (pneumococci and viridans streptococci) isolated from oral and respiratory tract infections and their complications, against one antibiotic of each of the following classes: quinolones, oxazolidinones and glycopeptides. MATERIAL AND METHODS: The Etest has been used in order to investigate the susceptibility of the isolates against levofloxacin, linezolid and vancomycin. RESULTS AND CONCLUSIONS: As expected, the results of the study indicated that all isolates were susceptible to linezolid and vancomycin. In contrast to the pneumococcal isolates, which were all susceptible to levofloxacin, 10% of the viridans strains showed resistance to this quinolone. When fluoroquinolones are needed as an alternative to the beta-lactam antibiotics in infections in which oral streptococci are involved, the in vitro susceptibility testing is required.