Group A Streptococci from Carriage and Disease in Portugal: Evolution of Antimicrobial Resistance and T Antigenic Types During 2000–2002

In this study, we analyzed the antimicrobial resistance properties and T antigenic types of 511 isolates collected in Lisbon district, Portugal, from throat swabs of healthy subjects (n = 341), during 2000–2002 and from diverse infection sites (n = 170) of outpatients and inpatients, during 1999–2002. Erythromycin resistance was higher in tonsillitis/pharyngitis (27.4%) and skin infection isolates (21.1%), than in carriage and invasive isolates (≤10%). Differences in erythromycin resistance among children and adults were noticed only for carriage isolates (9.3% in children and 21.1% in adults). Most erythromycin-resistant isolates from carriage (82.4%) and tonsillitis/pharyngitis (71.9%) showed the M phenotype. All M phenotype isolates (n = 53) carried mef(A), whereas all MLSB phenotype isolates (n = 19) carried erm(B) and not erm(A). Resistance to tetracycline [mediated by tet(M) in most isolates] was ≤6% in tonsillitis/pharyngitis and carriage isolates, 36.8% in skin infection isolates, and 44.1% in inv...