Antimicrobial Susceptibility and Survey of Macrolide Resistance Mechanisms amongStreptococcus pyogenesIsolated in Rio de Janeiro, Brazil

Abstract

A total of 357 clinical Streptococcus pyogenes isolates collected between 1994 and 1999 in Rio de Janeiro city were tested for susceptibility to 10 antimicrobial drugs by agar-diffusion tests. All isolates were susceptible to penicillin, cephems, and vancomycin. High resistance rates were observed for tetracycline (43.1%) and trimethoprim/sulfamethoxazole (77.9%). Three isolates (0.8%) were resistant to erythromycin, and three exhibited intermediate susceptibility. Determination of the erythromycin MICs by the agar dilution method, showed 1.6% of erythromycin resistant isolates (the three erythromycin-resistant and the three erythromycin-intermediate isolates found by agar-diffusion test). Of the erythromycin-resistant isolates subjected to the double-disc diffusion test for erythromycin and clindamycin, three isolates expressed the iMLSB and three the M phenotype. The resistance phenotypes were confirmed by comparing the clindamycin MICs determined under normal testing conditions and those determined after induction by pre-growth in 0.06 microg/ml of erythromycin. Three ermTR and three mefA-containing isolates were detected by PCR. In strains belonging to the iMLSB phenotype, two clones were identified by PFGE following restriction with SmaI. M phenotype isolates could not be restricted with SmaI. Our results indicate a low rate of erythromycin resistance among S. pyogenes isolated in Rio de Janeiro, Brazil, and pointed to the presence of both resistance mechanisms found in streptococci.

Polyclonal dissemination of tetracycline resistance among Streptococcus pyogenes paediatric isolates from Brazil

“…No difference in antibiotic resistance patterns could be observed among the three participating centres. This high rate of tetracycline resistance and absence of macrolide resistance is similar to the results obtained in previous studies in other areas of South America, including Brazil [10][11][12] (Table 2). This may be related to the low prescription rate of macrolides in Brazilian public hospitals; less than 3% of the acute pharyngitis were treated with macrolides in our study [34].…”

“…However, great variability across different areas has been reported [5] and scarce data are available for GAS isolated in South America [6][7][8][9]. GAS tetracycline resistance is also reported in many countries and data from South America show a proportion of resistant isolates ranging from 8 to 70% [10][11][12][13]. None of these recent studies have analyzed the presence of the tetracycline resistance-conferring genes.…”

Antibiotic Susceptibility of Streptococcus Pyogenes Isolated from Respiratory Tract Infections in Dakar, Senegal

“…All strains tested in this study were susceptible to vancomycin. These results are consistent with findings reported in other countries 32,33. The teicoplanin tested showed complete activity on all strains of S. pyogenes with a low MIC 90 of about 1 μg/mL.…”

Characterisation of the main clones of Streptococcus pyogenes carrying the ermA (subclass TR) gene in Spain

“…Complete characterisation of isolates is expensive and time consuming [2] and consequently the information available on erythromycin-resistant S. pyogenes clones circulating in Europe is mainly limited to the ermB and mef genes [13][14][15][16]. This study focuses on investigation of S. pyogenes isolates showing resistance to erythromycin mediated by the ermA gene.…”