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Volume 48, Number 5, October 2015

High prevalence of Streptococcus agalactiae from vaginas of women in Taiwan and its mechanisms of macrolide and quinolone resistance 


Wen-Tsung Lee, Mei-Chin Lai


Received: September 9, 2013    Revised: January 18, 2014    Accepted: March 11, 2014   

 

Corresponding author:

Mei-Chin Lai, Corresponding author. Department of Life Sciences, National Chung Hsing University, Number 250, Kuo-Kuang Road, Taichung 40227, Taiwan, ROC. 



 

Background and purpose: 

Streptococcus agalactiae (GBS), is the most common pathogen causing infections among perinatal women and neonatal babies. Nonetheless, there are few studies on the occurrence of GBS among the pregnant women and the mechanisms of GBS resistance to quinolones and macrolides in Taiwan. 



 

Methods:

GBS were isolated from vaginas of the pregnant and non-pregnant symptomatic women in Taiwan. The prevalence, antimicrobial susceptibility, and mechanisms of resistance against erythromycin and quinolone of total 188 isolates were studied. 



 

Results:

The isolation rate of GBS from pregnant women was significantly higher at 21.8% compare with the non-pregnant women of 13.2%. Antibiotic susceptibility test of the 188 GBS isolates revealed a high non-susceptible rate for erythromycin (50.0%) while the rate for levofloxacin was only 4.8%. Among 94 erythromycin non-susceptible GBS isolates, ermB gene was detected 83.1% (59/71) for those GBS that were non-susceptible to both clindamycin and tetracycline, which was significantly higher than GBS that are susceptible to clindamycin but resistant to tetracycline at 43.8% (7/16). No ermA or mef gene was detected in any isolate. Mutations were detected in the parC and gyrA genes in 14 out of 18 levofloxacin non-susceptible isolates. The predominant mutation type was the combination of Ser79Tyr in parC and Ser81Leu mutations in gyrA. 



 

Conclusion:

GBS is the most common isolated pathogens in vaginal infections in Taiwan, resistance to tetracycline and erythromycin is higher than the rate observed for other regions of the world, while the resistance rate for levofloxacin was relatively lower in Taiwan. 



 

Key words:

drug resistance, ermA gene, erythromycin, levofloxacin, macrolide, mef gene, quinolone, vaginal infection