Antibiotic susceptibility pattern and erythromycin resistance mechanisms in beta-hemolytic group G Streptococcus dysgalactiae subspecies equisimilis isolates from central Taiwan

作者：Lo Hsueh Hsia^*; Nien Hao Hsiang; Cheng Ya Yu; Su Fang Yi

来源：Journal of Microbiology, Immunology, and Infection, 2015, 48(6): 613-617.

DOI：10.1016/j.jmii.2014.04.003

• antimicrobial susceptibility
• central Taiwan
• Streptococcus dysgalactiae subspecies equisimilis

Background/Purpose: 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 (cMLS(B), 35.6%), and inducible MLSB (iMLS(B), 15.3%). All M phenotypic isolates carried mefA. The most prevalent genotypes among cMLS(B) and iMLS(B) phenotypic isolates were ermB, followed by ermTR. One isolate with cMLS(B) phenotype carried both ermB and ermTR, whereas one isolate with iMLS(B) phenotype carried both ermB and ermC.
Conclusion: 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.

• 出版日期2015-12
• 单位中国医科大学