Genotypes and serotypes correlation among macrolide-resistant Streptococcus agalactiae isolates in Zaragoza, Spain (2002–2004)

Abstract number: p1596

Llaneza  M.E., Seral  C., Castillo  F.J., Duran  E., García  C., Millán  I., Sáez-Nieto  J.A., Rubio  M.C., Gómez-Lus  R.


To analyze the phenotype-genotype as well as the genotype-serotype correlation among macrolide-resistant Streptococcus group B (GBS) isolated in Zaragoza, Spain, from May 2002 to April 2004.


A total of 562 GBS were isolated from May 2002 to April 2004 at the University Hospital of Zaragoza, Spain: 354 GBS obtained from vaginal swabs of pregnant women and 208 GBS obtained from non-pregnant women. The erythromycin resistant-GBS were identified, phenotypically analysed, screened by PCR for mre(A) gene and for erythromycin resistance genes: erm(B), erm(TR), mef(A) and mef(E), and serotyped with type specific antisera for serotypes Ia, Ib, II, III, IV, and V.


Among the total of GBS, 161 (28.65%) were erythromycin-resistant: 86 (24.29%) erythromycin–resistant GBS were isolated from vaginal swabs of pregnant women and 75 (36.06%) from non-pregnant women. The frequency of serotypes in 151 erythromycin-resistant GBS tested, the distribution of their resistance genes and the distribution of serotypes among the different genotypes are illustrated in the table. NT, nontypeable, The mre(A) gene was found in all the GBS strains tested. MICs of erythromycin in erythromycin-resistant GBS were: MIC50 and MIC90, >128 mg/L; range, 4 to >128 mg/L for GBS harbouring erm(B) and erm(B)+erm(TR) and MIC50 and MIC90, 8 mg/L and >128 mg/L, respectively; range, 0.5 to >128 mg/L for GBS harbouring erm(TR).


Erm(B) was the erythromycin-resistant gene most prevalent among the GBS isolates and these isolates showed the highest MICs of erythromycin. The commonest serotypes among erythromycin-resistant GBS isolated were III, II and I, and showed genotypic variability harbouring either of the two most prevalent genes, erm(B) or/and erm(TR).

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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