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Volume 47, Number 6, December 2015

Correlation of virulence genes to clinical manifestations and outcome in patients with Streptococcus dysgalactiae subspecies equisimilis bacteremia 

Chia-Ta Tsai, Chih-Yu Chi, Cheng-Mao Ho, Po-Chang Lin, Chia-Hui Chou, Jen-Hsien Wang, Jui-Hsing Wang, Hsiao-Chuan Lin, Ni Tien, Kuo-Hsi Lin, Mao-Wang Ho, Jang-Jih Lu

Received: April 24, 2013    Revised: August 18, 2013    Accepted: August 30, 2013   


Corresponding author:

Corresponding author. Division of Infectious Diseases, Department of Internal Medicine, China Medical University Hospital, Number 2,
Yu-Der Road, Taichung 40447, Taiwan.
** Corresponding author. Department of Laboratory Medicine, Chang Gung Memorial Hospital at Linkou, Number 5, Fusing Street, Kweishan,
Taoyuan 333, Taiwan.
E-mail addresses: (M.-W. Ho), (J.-J. Lu). 


Background and purpose: 

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is increasingly recognized as a human pathogen responsible for invasive infection and streptococcal toxic shock syndrome (STSS). The pathogen possesses virulence genes that resemble those found in Streptococcus pyogenes (GAS). We analyzed the association between these specific toxic genes, clinical presentations, and outcome in patients with SDSE infections. 



Patients (older than 18 years) with community-acquired invasive bacteremia caused by SDSE bacteremia who were undergoing treatment at China Medical University Hospital from June 2007 to December 2010 were included in this study. Multiplex polymerase chain reaction was performed to identify virulence genes of the SDSE isolates. Demographic data, clinical presentations, and outcome in patients with SDSE infections were reviewed and analyzed. 



Forty patients with 41 episodes of SDSE bacteremia were reviewed. The median age of the patients with SDSE infection was 69.7 years; 55% were female and 78% had underlying diseases. Malignancy (13, 33%) and diabetes mellitus (13, 33%) were the most common comorbidities. The 30-day mortality rate was 12%. Compared with the survivors, the non-survivors had a higher rate of diabetes mellitus (80% vs. 26%), liver cirrhosis (60% vs.11%), shock (60% vs.17%), STSS (60% vs. 8%), and a high Pittsburgh bacteremia score >4 (40% vs. 6%). Most isolates had scpA, ska, saga, and slo genes, whereas speC, speG, speH, speI, speK, smez, and ssa genes were not detected. speA gene was identified only in one patient with STSS (1/6, 17%). All isolates were susceptible to penicillin, cefotaxime, levofloxacin, moxifloxacin, vancomycin, and linezolid.



In invasive SDSE infections, most isolates carry putative virulence genes, such as scpA, ska, saga, and slo. Clinical SDSE isolates in Taiwan remain susceptible to penicillin cefotaxime, and levofloxacin. 


Key words:

Phoenix Automated Microbiology System, Streptococcal toxic shock syndrome, Streptococcus dysgalactiae subsp. dysgalactiae, Streptococcus dysgalactiae subsp. equisimilis, Superantigen