The Viriato Study: update of antimicrobial susceptibility data of bacterial pathogens from community-acquired respiratory tract infections in Portugal in 2003 and 2004.
The Viriato Study is a nationwide, prospective, multicenter surveillance study of the antimicrobial susceptibility of bacterial pathogens commonly associated with community-acquired respiratory tract infections in Portugal. In 2003 and 2004 a total of 2945 isolates was recovered in the 29 laboratories that participated in the study. Testing was undertaken in a central laboratory. Of the 513 Streptococcus pyogenes strains isolated from patients with acute tonsillitis all were susceptible to penicillin and other beta-lactams but 18.9% were resistant to erythromycin, clarithromycin and azithromycin. The M phenotype dominated (67%), conferring resistance to erythromycin (MIC90 = 16 mg/L), clarythromycin and azithromycin, but susceptibility to clindamycin (MIC90 = 0.094 mg/L). From patients with lower respiratory tract infection 1,300 strains of Streptococcus pneumoniae, 829 of Haemophilus influenzae, and 303 of Moraxella catarrhalis were studied. Among S. pneumoniae isolates 18.4% were resistant to penicillin (3.5% showing high-level resistance), 7.1% to cefuroxime, 0.5% to amoxicillin and amoxicillin/clavulanate, 18.8% to erythromycin, clarithromycin and azithromycin, 14.9% to tetracycline, 16.5% to co-trimoxazole, and 0.4% to levofloxacin. Beta-lactamases were produced by 10.0% of H. influenzae and 96.4% of M. catarrhalis. In H. influenzae resistance to clarithromycin was 5.5% and to co-trimoxazole was 13.4%. Most strains were susceptible to amoxicillin/clavulanate, cefuroxime, azithromycin, tetracycline and ciprofloxacin. In M. catarrhalis resistance to co-trimoxazole was 27.1% and to tetracycline 1.0%. All strains were susceptible to amoxicillin/clavulanate, cefuroxime, clarithromycin, azithromycin and ciprofloxacin. Penicillin was the most active antimicrobial agent against S. pyogenes and amoxycillin/clavulanate and the quinolones the most active in vitro simultaneously against S. pneumoniae, H. influenza and M. catarrhalis.
Microbiology Institute, Lisbon Medical School.
J
J
Melo-Cristino
Letícia
L
Santos
Mário
M
Ramirez
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017714:Community-Acquired Infections / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D006193:Haemophilus influenzae / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D001936:Moraxella catarrhalis / Q000187:drug effects*; D011159:Population Surveillance; D011174:Portugal; D011446:Prospective Studies; D012141:Respiratory Tract Infections / Q000382:microbiology*; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D013297:Streptococcus pyogenes / Q000187:drug effects*
D000900:Anti-Bacterial Agents