title: Antibiotic susceptibility pattern and erythromycin resistance mechanisms in beta-hemolytic group G Streptococcus dysgalactiae subspecies equisimilis isolates from central Taiwan.
abstract: OBJECTIVE
  Information concerning antibiotics susceptibilities of beta-hemolytic group G Streptococcus dysgalactiae subspecies equisimilis (SDSE) clinical isolates in central Taiwan was limited.
  
  
  METHODS
  Totally, 246 SDSE isolates were collected from mainly five regional hospitals, from February 2007 to August 2011. Disk diffusion method, broth microdilution method, and clindamycin induction test (D test) were respectively performed according to the guidelines of the Clinical and Laboratory Standards Institute. Polymerase chain reaction was used to detect the corresponding erythromycin resistance genes.
  
  
  RESULTS
  All isolates were susceptible to penicillin, cefotaxime, and vancomycin. The rate of erythromycin resistance was 24.0% (59/246), whereas that of clindamycin resistance was 12.2% (30/246). The resistance rates of isolates from different hospitals varied from 15.0% to 45.5% for erythromycin and from 7.1% to 36.4% for clindamycin. For erythromycin-resistant SDSE isolates, three different phenotypes with resistance to macrolides (M), lincosamides (L), and type B streptogramins (SB) were observed: M (49.2%), constitutive MLSB (cMLSB, 35.6%), and inducible MLSB (iMLSB, 15.3%). All M phenotypic isolates carried mefA. The most prevalent genotypes among cMLSB and iMLSB phenotypic isolates were ermB, followed by ermTR. One isolate with cMLSB phenotype carried both ermB and ermTR, whereas one isolate with iMLSB phenotype carried both ermB and ermC.
  
  
  CONCLUSIONS
  This is the first trial investigating the antimicrobial susceptibility pattern and erythromycin resistance mechanisms of beta-hemolytic group G SDSE isolates in central Taiwan. The resistance rates for both erythromycin and clindamycin varied significantly among hospitals located in this area and should be monitored continuously in the future.
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, Taiwan. Electronic address: sslo@ctust.edu.tw.
authors.forename: Hsueh-Hsia
authors.initials: HH
authors.lastname: Lo
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, Taiwan.
authors.forename: Hao-Hsiang
authors.initials: HH
authors.lastname: Nien
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, Taiwan.
authors.forename: Ya-Yu
authors.initials: YY
authors.lastname: Cheng
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, Taiwan; Department of Laboratory Medicine, China Medical University Hospital, Taichung, Taiwan.
authors.forename: Fang-Yi
authors.initials: FY
authors.lastname: Su
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D002981:Clindamycin / Q000494:pharmacology*; D003428:Cross Infection / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004917:Erythromycin / Q000494:pharmacology*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D013290:Streptococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D013291:Streptococcus / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*; D013624:Taiwan
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C117866:MefA protein, Streptococcus; D008565:Membrane Proteins; D002981:Clindamycin; D004917:Erythromycin
keywords: Streptococcus dysgalactiae subspecies equisimilis; antimicrobial susceptibility; central Taiwan