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Volume 50, Number 6, December 2017

Highly prevalent emmSTG840.0 and emmSTC839.0 types of erythromycin non-susceptible group G Streptococcus isolated from bacteremia in southern Taiwan 

Po-Xing Zheng, Yuen-Chi Chan, Chien-Shun Chiou, Cheng-Lu Hsieh, Chuan Chiang-Ni, Jiunn-Jong Wu


Corresponding author:

Jiunn-Jong Wu, Corresponding author. Department of Biotechnology and Laboratory Science in Medicine, School of Biomedical Science and Engineering, National Yang-Ming University. No. 155, Sec. 2, Linong Street, Taipei, 112, Taiwan. Fax: +886 2 28264092. 


Background and purpose: 

Group G Streptococcus (GGS) infections in human have increased. Treatment relied on antibiotic therapy, including erythromycin. However, information regarding the dominant strains and erythromycin susceptibility in GGS bacteremia is limited. 



A total of 134 GGS were isolated from patients with bacteremia in a university hospital of southern Taiwan during 1993–2010. The erythromycin susceptibility was determined by disc diffusion and agar dilution assays. The bacterial species was determined by MALDI-TOF. The presence of erythromycin-resistant genes and emm types were determined by polymerase chain reaction and sequence. The clonal spreading was analyzed by pulsed-field gel electrophoresis with SmaI or SgrAI digestion. 



The annual erythromycin non-susceptible rate varied, with an average of 40.3%. All erythromycin non-susceptible strains belonged to the Streptococcus dysgalactiae. No erythromycin non-susceptible strains belong to the anginosus group. The most prevalent erythromycin-resistant gene was mefA (57.4%), followed by ermB (37%), and ermA (3.7%). The N terminal hyper variable region of emm was sequenced to determine the emm type, and only S. dysgalactiae had the emm gene. The most prevalent emm types were emmSTG840.0 (17.2%), emmSTG485.0 (10.4%), and emmSTC839.0 (9.0%). 73% and 47% of the strains with only mefA and ermB belonged to emmSTG840.0 and emmSTC839.0 types, respectively. Pulsed-field gel electrophoresis showed that different clones of emmSTG840.0 and emmSTC839.0 strains were spread in this region during the 18 years of surveillance. 



Our data indicate that there were dominant emm types with erythromycin non-susceptibility in S. dysgalactiae isolated from bacteremia in Taiwan, and thus constant surveillance is warranted. 


Key words:

emm, Epidemiology, Erythromycin, Group G Streptococcus