Susceptibility of macrolide and beta-lactam antibiotics of Streptococcus pyogenes strains isolated over a four-year period in central Italy.
In vitro susceptibility to erythromycin, azithromycin, penicillin G, ceftriaxone and ceftibuten was investigated in 190 Streptococcus pyogenes strains isolated over a 4-year period (1991-1994) from patients attending a university hospital located in central Italy. The rate of susceptibility to macrolide antibiotics of the S. pyogenes strains showed a progressive decrease (from 90.3% in 1991 to 79.5% in 1994), while all strains were susceptible to the three beta-lactam antibiotics. Owing to the reduced prevalence of macrolide-susceptible S. pyogenes strains, in vitro susceptibility testing of streptococcal isolates appears to be always necessary before starting a macrolide-based chemotherapy. Concerning beta-lactams, ceftriaxone presented minimum inhibitory concentrations (MIC) always equal to or lower than those of penicillin G, while the oral long-acting cephalosporin, ceftibuten, had MICs higher than those of the other beta-lactams, although in the susceptible range. Results of in vitro susceptibility testing are discussed in relation to their implications for antimicrobial chemotherapy of S. pyogenes infections.
Cellesi
C
C
Institute of Infectious Diseases, University of Siena, Italy.
Chigiotti
S
S
Zanchi
A
A
Mencarelli
M
M
Corbisiero
R
R
Rossolini
G M
GM
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017963:Azithromycin / Q000494:pharmacology; D000077722:Ceftibuten; D002443:Ceftriaxone / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology; D016009:Chi-Square Distribution; D004917:Erythromycin / Q000494:pharmacology; D006801:Humans; D007558:Italy; D008826:Microbial Sensitivity Tests; D010400:Penicillin G / Q000494:pharmacology; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism; D018440:beta-Lactam Resistance
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D004917:Erythromycin; D002443:Ceftriaxone; D017963:Azithromycin; D000077722:Ceftibuten; D010400:Penicillin G