CONICET | Buscador de Institutos y Recursos Humanos

Background: Streptococcus agalactiae (group B streptococcus [GBS]) is the leading cause of neonatal and maternal sepsis. Penicillin is the drug of choice for prophylaxis and treatment of GBS disease, but erythromycin or clindamycin is used for those allergic to penicillin. A lincosamide nucleotidyl transferase, encoded by lnuB, which was first found in Enterococcus faecium has been reported only in two occasions in GBS. Methods: S. agalactiae was obtained from vagina and rectum swabs of a 29 years old pregnant female. Detection of GBS colonization was performed according to universal screening recommendations. Identification was confirmed by a conventional scheme. Disk-diffusion antimicrobial susceptibility testing, D-test and MICs were performed according to CLSI recommendations.The strain was screened by PCR for ermTR, ermB or mefA, mefE and lnuB determinants. Results: A penicillin sensitive S. agalactiae isolate recovered in GBS screening showed resistance to clindamycin and lincomycin but susceptibility to erythromycin. MICs values confirmed resistance to lincomycin (MIC = 64 μg/ml) and susceptibility to erythromycin (MIC = 0.125μg/ml). No PCR products were obtained for the common resistant determinants in the analyzed isolate. However, lnuB was detected by PCR, and confirmed by sequencing. Sequence (deposited on data bases) displayed 99% of similarity when compared to lnuB from E. faecium. Conclusion: This is the first report of lnuB genotype in S. agalactiae in Argentina. Spread to other GBS strains and other streptococcal species must be considered as potentially emerging undetected, considering that a similar unusual phenotype was recently described in Streptococcus pneumoniae.

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