Increased prevalence of erythromycin resistance in streptococci: substantial upsurge in erythromycin-resistant M phenotype in Streptococcus pyogenes (1979-1998) but not in Streptococcus pneumoniae (1985-1999) in Taiwan.
A total of 394 nonduplicate isolates of Streptococcus pyogenes collected from 1979 to 1998 and 267 nonduplicate isolates of Streptococcus pneumoniae collected from October, 1998, to May, 1999, in Taiwan were evaluated. Among the 220 erythromycin-resistant (MIC, > or =1 microg/ml) S. pyogenes isolates, 35% had an M phenotype and 65% had an ML phenotype (inducible resistance [iML], 0.5%, and constitutive resistance [cML], 64.5%). Among the 243 erythromycin-resistant S. pneumoniae isolates, the majority (65.4%) had an ML phenotype (iML, 0.4%, and cML, 65%) and 34.6% had an M phenotype. A substantial upsurge in the incidence of M-phenotype erythromycin-resistant isolates was found with time for S. pyogenes (0% in 1979-1984 and 100% in 1997-1998), and an increasing incidence of M-phenotype among erythromycin-resistant S. pneumoniae was also noted (<20% before 1994 and 45.4% in 1999). All S. pyogenes and all but four S. pneumoniae isolates exhibiting a cML or iML phenotype had harbored the ermAM gene. The presence of the mefA gene was demonstrated in all isolates of S. pyogenes and the mefE gene in all but four S. pneumoniae isolates exhibiting the M phenotype. Due to the increasing susceptibility of S. pyogenes and S. pneumoniae isolates to clindamycin, susceptibility tests of these two organisms to macrolides and clindamycin should be performed simultaneously in the clinical microbiology laboratory, particularly in areas with high rates of macrolide resistance.
Hsueh
Po-Ren
PR
Department of Laboratory Medicine, National Taiwan University Hospital, Taipei.
Teng
Lee-Jene
LJ
Lee
Li-Na
LN
Yang
Pan-Chyr
PC
Ho
Shen-Wu
SW
Lue
Hung-Chi
HC
Luh
Kwen-Tay
KT
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004351:Drug Resistance; D004917:Erythromycin / Q000494:pharmacology*; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D013290:Streptococcal Infections / Q000188:drug therapy* / Q000453:epidemiology*; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D013297:Streptococcus pyogenes / Q000187:drug effects*; D013624:Taiwan / Q000453:epidemiology
D000900:Anti-Bacterial Agents; D004917:Erythromycin