TRENDS IN ANTIBIOTIC-RESISTANCE OF STAPHYLOCOCCI OVER AN 8-YEAR PERIOD - DIFFERENCES IN THE EMERGENCE OF RESISTANCE BETWEEN COAGULASE POSITIVE AND COAGULASE-NEGATIVE STAPHYLOCOCCI

The antimicrobial susceptibilities of 1058 Staphylococcus aureus and 2 ,163 coagulase-negative staphylococci (CNS) isolates obtained from cli nical specimen between 1988 and 1995, were determined against 13 antis taphylococcal antibiotics. During the study period the resistance of S taphylococcus aureus to ciprofloxacin, ceftazidime, and norfloxacin in creased significantly by 7%, 4%, and 6%, respectively (p less than or equal to 0.001). By comparison, the antibiotic resistance of CNS to ce ftazidime, oxacillin, norfloxacin, ciprofloxacin, fusidic acid, and ce foxitin increased by 20%, 17%, 15%, 14%, 12% and 10%, respectively (p less than or equal to 0.001). Invasive and noninvasive S. aureus had s imilar antibiotic resistance, whereas CNS invasive isolates were more resistant than noninvasive isolates to every antibiotics, except vanco mycin and fusidic acid. These differences were significant (p < 0.001) for oxacillin, cefoxitin, and clindamycin. Our observations confirm t hat staphylococci and particularly CNS isolates show an important rate of increased resistance to the standard antimicrobials used for thera py, and that the rate of emergence of resistance differ considerably b etween coagulase-positive and coagulase-negative staphylococci.