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


METHODS
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.
Muller
Anouk E
AE
Medical Centre Haaglanden (MCH), Department of Obstetrics and Gynecology, Lijnbaan 32, 2512 VA The Hague, The Netherlands. a.muller@mchaaglanden.nl
Valkenburg-van den Berg
Arijaan W
AW
Kreft
Deborah
D
Oostvogel
Paul M
PM
Sprij
Arwen J
AJ
van Belkum
Alex
A
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D002353:Carrier State; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D018942:Macrolides / Q000494:pharmacology*; D008565:Membrane Proteins / Q000235:genetics; D008780:Methyltransferases / Q000235:genetics; D009426:Netherlands / Q000453:epidemiology; D010641:Phenotype; D011159:Population Surveillance; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology* / Q000382:microbiology* / Q000517:prevention & control; D011263:Pregnancy Trimester, Third; D015995:Prevalence; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D013292:Streptococcus agalactiae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D018942:Macrolides; C117866:MefA protein, Streptococcus; D008565:Membrane Proteins; C111078:ErmTR protein, bacteria; D008780:Methyltransferases