Low rate of carriage of macrolide-resistant group B streptococci in pregnant women in The Netherlands

Eur J Obstet Gynecol Reprod Biol. 2008 Mar;137(1):17-20. doi: 10.1016/j.ejogrb.2007.04.001. Epub 2007 May 7.


Objectives: To describe prevalence of phenotypic and genotypic macrolide-resistance among GBS isolates in pregnant women and explore the possibility of clonal spread of resistant GBS isolates in a multicultural population.

Study design: Antimicrobial resistance patterns of 107 GBS isolates obtained from asymptomatic pregnant women were determined using E-tests. Macrolide resistance genes mef(A), erm(TR) and erm(B) were determined with PCR and a subset of 39 isolates, including the 8 isolates harbouring macrolide resistance genes, was subjected to RAPD analysis to detect clonal spreading.

Results: Resistance to erythromycin and clindamycin was found in 8% and 7%, respectively. Macrolide resistance genes mef(A), erm(TR) and erm(B) were found in 1, 2 and 5 isolates, respectively; only five of these eight isolates exhibited both genotypic as well as phenotypic resistance. One genotype occured in 36% of the subset.

Conclusions: Earlier reports on prevalence of phenotypic resistance were confirmed. Among the susceptible isolates one clonal type of GBS was clearly predominant; one of the resistant isolates shared its genotype. When such clonal types acquire resistance traits in the future, GBS disease may become harder to control.

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / genetics
  • Carrier State
  • Drug Resistance, Bacterial / genetics*
  • Female
  • Genotype
  • Humans
  • Macrolides / pharmacology*
  • Membrane Proteins / genetics
  • Methyltransferases / genetics
  • Netherlands / epidemiology
  • Phenotype
  • Population Surveillance
  • Pregnancy
  • Pregnancy Complications, Infectious / epidemiology*
  • Pregnancy Complications, Infectious / microbiology*
  • Pregnancy Complications, Infectious / prevention & control
  • Pregnancy Trimester, Third
  • Prevalence
  • Streptococcal Infections / epidemiology*
  • Streptococcal Infections / microbiology
  • Streptococcal Infections / prevention & control
  • Streptococcus agalactiae / drug effects
  • Streptococcus agalactiae / genetics*
  • Streptococcus agalactiae / isolation & purification


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Macrolides
  • MefA protein, Streptococcus
  • Membrane Proteins
  • ErmTR protein, bacteria
  • Methyltransferases