Clonal diversity among erythromycin-resistant  -haemolytic Streptococcus isolates in La Rioja, Spain

Objective: To analyse clonal diversity in 72 erythromycin-resistant [beta]-haemolytic streptococci. Methods: Clonal relationships were studied for streptococci of groups A (GAS, n = 30), B (GBS, n = 34), C (GCS, n = 4) and G (GGS, n = 4) by means of PFGE. Streptococcal isolates were obtained from a 450-bed hospital in Spain during the following periods: GAS (1996-2001), GBS (1999-2001), GCS and GGS (1997-2000). Results: Twenty-two of the 30 GAS isolates showed the M resistance phenotype and harboured the mef(A) gene. Five unrelated PFGE patterns were identified among these 22 GAS isolates. Sixteen of them, obtained during four different years of the study, showed one of the two predominant PFGE patterns. The remaining eight GAS isolates showed the MLS