Distribution of serotypes in tetracycline-resistant Streptococcus group B isolated in Zaragoza, Spain
Abstract number: p1597
Llaneza M.E., Seral C., Castillo F.J., Salvo S., Martinez A., Pardos M., Rubio M.C., Sáez-Nieto J.A., Gómez-Lus R.
To analyse the tetracycline-resistant genotypes in erythromycin-resistant Streptococcus group B (GBS) isolated in Zaragoza, Spain collected from April 2002 to May 2004, and their serotype distribution.
We studied the rates of resistance to tetracycline and minocycline among 161 erythromycin-resistant GBS strains isolated at the University Hospital Lozano Blesa of Zaragoza, Spain. Isolates were subsequently phenotypically analysed by means of the disk diffusion method and screened by PCR for erythromycin and tetracycline resistance genes [erm(B), erm(TR), mef(A/E), tet(M) and tet(O)]. The susceptibility to erythromycin, josamycin, tetracycline and minocycline was tested by the agar dilution method according to the NCCLS. The strains were serotyped with type specific antisera for serotypes Ia, Ib, II, III, IV, and V.
Among the total of 161 isolates of macrolide-resistant GBS collected from May 2002 to April 2004 in our hospital (28.6% of the total SGB isolated), 124 (78.85%) were tetracycline-resistant. The distribution of tet(M) and tet(O) among the erythromycin-resistant GBS harbouring erm(B) was (66.1% and 54.2%, repectively) and harbouring erm(TR) was (63.8% and 34.5%). The distribution of tetracycline resistance genes and serotypes among the different genotypes in 121 GBS are illustrated in the table.*NT: non typable Isolates carrying tet(M) or tet(M)+tet(O) presented the following MICs: tetracycline (MIC90 64, MIC50 32, range 16128 mg/L); minocycline (MIC90 32, MIC50 16, range 432 mg/L). Isolates carrying tet(O) presented the following MICs: tetracycline (MIC90 64, MIC50 32, range 3264 mg/L); minocycline (MIC90 16, MIC50 16, range 432 mg/L).
The majority (61.1%) of tetracycline-resistant GBS harboured tet(M) alone or in combination with tet(O). The most prevalent serotypes among the total of tetracycline-resistant GBS was the serotype III (38%) and the serotype II (28%). Serotype III was more prevalent among the GBS harbouring the tet(M) gene and serotype II was more prevalent among the GBS harbouring the tet(O) gene.
|Session name:||XXIst ISTH Congress|
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