A multicentre study: Staphylococcus and Enterococcus susceptibility to antibiotics

A multicentre study to evaluate the susceptibility of Gram-positive cocci isolated from clinical samples, was performed by six centres working in different areas of Italy. We examined 4,544 strains of Staphylococcus aureus, 4,381 strains of coagulase-negative staphylococci and 2,478 strains of enterococci. The following antibiotics were tested: penicillin G, ampicillin, amoxicillin, piperacillin, imipenem, oxacillin, ofloxacin, pefloxacin, ciprofloxacin, gentamicin, tobramycin, amikacin, netilmicin, rifampicin, clindamycin, tetracycline, cotrimoxazole, erythromycin, chloramphenicol, vancomycin and teicoplanin. Oxacillin-susceptible staphylococci confirmed their susceptibility to many other antimicrobial agents while oxacillin-resistant strains confirmed their multiple and frequent resistance to antibiotics. Resistance to oxacillin, cotrimoxazole and chloramphenicol was more frequent in coagulase-negative staphylococci than in Staphylococcus aureus. Aminoglycosides, rifampicin and quinolones were more active against coagulase-negative staphylococci than against Staphylococcus aureus. Enterococci were susceptible to penicillins and imipenem, and moderately susceptible to ciprofloxacin. Susceptibility of 70-79% was observed with high levels of aminoglycosides. Excellent results against staphylococci and enterococci were observed with vancomycin and teicoplanin.