Prevalence and Mechanisms of Macrolide Resistance in Invasive and Noninvasive Group B Streptococcus Isolates from Ontario, Canada

Autor: de Azavedo, Joyce C. S., McGavin, Mary, Duncan, Carla, Low, Donald E., McGeer, Allison
Zdroj: Antimicrobial Agents and Chemotherapy; December 2001, Vol. 45 Issue: 12 p3504-3508, 5p
Abstrakt: ABSTRACTMacrolide resistance has been demonstrated in group B streptococcus (GBS), but there is limited information regarding mechanisms of resistance and their prevalence. We determined these in GBS obtained from neonatal blood cultures and vaginal swabs from pregnant women. Of 178 isolates from cases of neonatal GBS sepsis collected from 1995 to 1998, 8 and 4.5% were resistant to erythromycin and clindamycin, respectively, and one isolate showed intermediate penicillin resistance (MIC, 0.25 μg/ml). Of 101 consecutive vaginal or rectal/vaginal isolates collected in 1999, 18 and 8% were resistant to erythromycin and clindamycin, respectively. Tetracycline resistance was high (>80%) among both groups of isolates. Of 32 erythromycin-resistant isolates, 28 possessed the ermmethylase gene (7 ermBand 21 ermTR/ermA) and 4 harbored the mefAgene; one isolate harbored both genes. One isolate which was susceptible to erythromycin but resistant to clindamycin (MIC, 4 μg/ml) was found to have thelinBgene, previously identified only inEnterococcus faecium. The mreAgene was found in all the erythromycin-resistant strains as well as in 10 erythromycin-susceptible strains. The rate of erythromycin resistance increased from 5% in 1995–96 to 13% in 1998–99, which coincided with an increase in macrolide usage during that time.
Databáze: Supplemental Index
načítá se...