The Viriato study: update on antimicrobial resistance of microbial pathogens responsible for community-acquired respiratory tract infections in Portugal.

Background: The Viriato study is a prospective, multicentre laboratory-based surveillance study of antimicrobial susceptibility in which 30 microbiology laboratories throughout Portugal are asked to isolate identify and submit to a central laboratory for testing Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis responsible for community-acquired lower respiratory tract infections and Streptococcus pyogenes from tonsillitis.