Prevalence and mechanisms of erythromycin and clindamycin resistance in clinical isolates of β-haemolytic streptococci of Lancefield groups A, B, C and G in Seville, Spain

Abstract

Susceptibility to erythromycin and clindamycin was determined in 860 consecutive clinical isolates of β-haemolytic streptococci belonging to groupsA (GAS, n = 134), B (GBS, n = 689), C (GCS, n = 19) and G (GGS, n = 18). Erythromycin resistance was 26.1% in GAS, 15.7% in GBS, 5.3% in GCS and 33.3% in GGS. The highest rate of clindamycin resistance (33.3%) was in GGS, followed by GBS (15.8%), GCS (15.8%) and GAS (5.2%). The Mphenotype was predominant in GAS (80%), the constitutive MLSB phenotype was predominant in GBS (75%), and all GGS isolates showed the inducible MLSB phenotype. The uncommon erythromycin-susceptible and clindamycin-resistant phenotype was found in four GBS and two GCS isolates. © 2007 The Authors Journal Compilation © 2007 European Society of Clinical Microbiology and Infectious Diseases.