Five-year analysis of antimicrobial susceptibility of the Streptococcus milleri group

Susceptibility to 17 antibiotics was studied in 180 strains of the Streptoc occus milleri group (88 Streptococcus anginosus, 63 Streptococcus constella tus, and 29 Streptococcus intermedius) isolated over a 5-year period. Minim um inhibitory concentrations of penicillin were in the intermediate range f or 5.6% of the strains. Resistance to erythromycin and clindamycin was foun d in 17.1% and 16.6% of the isolates, respectively. A steady increase in th e susceptibility to ciprofloxacin was observed over the study period. Imipe nem was the most active beta-lactam agent tested. Glycopeptide antibiotics showed excellent activity. Only slight differences between the three specie s were found in terms of antibiotic susceptibility. Intermediate resistance to penicillin is appearing among the Streptococcus milleri group in our ar ea; consequently, care must be taken when choosing a macrolide for the mana gement of infections caused by these microorganisms.