Genotypic characterization of macrolide-resistant strains of Streptococcus pneumoniae isolated in Quebec, Canada, and in vitro activity of ABT-773 and telithromycin.
Increasing resistance of Streptococcus pneumoniae to macrolides represents a challenge for clinicians. New ketolides have an enhanced activity against macrolide-resistant strains. Four hundred and seventy-four strains of S. pneumoniae were collected during the 2000-2001 season in Quebec through a surveillance network. Macrolide resistance was 20.2%, and significantly higher in non-invasive strains versus invasive ones (22.4% versus 14.8%), and in children (30%) versus adults (14.8%). For susceptible strains, MIC(90)s of ABT-773 and telithromycin were 0.008 and 0.015 mg/L. Among the 96 macrolide-resistant strains, 56 (58%) were erm(B), 35 (37%) carried the mef(A) gene, four were carrying both genes and one none. ABT-773 and telithromycin were very active against all these resistant strains irrespective of the resistance mechanism, with MIC(90)s of 0.25 and 0.5 mg/L, respectively.
Hôpital Maisonneuve-Rosemont, 5415 L'Assomption, Montreal, Quebec H1T 2M4.
K
K
Weiss
C
C
Guilbault
L
L
Cortes
C
C
Restieri
D E
DE
Low
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005260:Female; D005798:Genes, Bacterial / Q000235:genetics; D005838:Genotype; D006801:Humans; D048628:Ketolides; D018942:Macrolides; D008297:Male; D008826:Microbial Sensitivity Tests; D011008:Pneumococcal Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D011792:Quebec / Q000453:epidemiology; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D048628:Ketolides; D018942:Macrolides; D004917:Erythromycin; C405499:cethromycin; C106791:telithromycin