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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. 



 

Methods:

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. 



 

Results:

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. 



 

Conclusion:

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