Prevalence of polyclonal mefA-containing isolates among erythromycin-resistant group A streptococci in Southern Taiwan.
A total of 204 nonrepetitive isolates of group A streptococci (GAS), including 107 randomly collected between 1992 and 1995 and 66 and 31 consecutively collected in 1997 and 1998, respectively, from a university hospital in southern Taiwan were examined to determine the prevalence and mechanisms of erythromycin resistance among these isolates. Resistance to erythromycin was detected in 129 isolates (63.2%) by the agar dilution test. Of these, 42 isolates (32.6%) were assigned to the constitutive macrolide, lincosamide, and streptogramin B resistance (cMLS) phenotype, and all carried the ermB gene; 4 (3.1%) were assigned to the inducible MLS resistance (iMLS) phenotype, and all harbored the ermTR gene; and 83 (64.3%) were erythromycin resistant but susceptible to clindamycin (M phenotype), and all possessed the mefA gene. Distributed by years, the rates of erythromycin resistance and different phenotypes were 61.7% (53.0% cMLS, 6.1% iMLS, and 40.9% M phenotype) between 1992 and 1995, 62.1% (12.2% cMLS and 87.8% M phenotype) in 1997, and 71. 0% (9.1% cMLS and 90.9% M phenotype) in 1998. Pulsed-field gel electrophoresis showed that all but 2 cMLS isolates were clonal in origin, and 17 clones were detected among the M-phenotype isolates. These results indicate that the high incidence and increasing rate of erythromycin-resistant GAS in southern Taiwan are due to the prevalence of multiple M-phenotype clones and that clindamycin may be the drug of choice for the treatment of infections with GAS in penicillin-hypersensitive patients in this area.
Yan
J J
JJ
Department of Pathology, National Cheng Kung University Medical Center, Tainan, Taiwan.
Wu
H M
HM
Huang
A H
AH
Fu
H M
HM
Lee
C T
CT
Wu
J J
JJ
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins; D004352:Drug Resistance, Microbial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004917:Erythromycin / Q000494:pharmacology*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics*; D008780:Methyltransferases / Q000235:genetics; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D015995:Prevalence; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D013624:Taiwan / Q000453:epidemiology
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C117866:MefA protein, Streptococcus; D008565:Membrane Proteins; D004917:Erythromycin; C111078:ErmTR protein, bacteria; D008780:Methyltransferases; C035181:rRNA (adenosine-O-2'-)methyltransferase