RESUMEN

A random-amplified polymorphic DNA assay using partially degenerate oligonucleotides as primers was used for the characterization of 78 epidemiologically related and unrelated clinical isolates of Streptococcus agalactiae belonging to different serotypes. Thirty distinct amplification profiles were obtained among 52 unrelated S. agalactiae isolates assigned to nine groups by serotyping (including 3 nontypeable strains), uncovering the extent of genomic heterogeneity existent within serotypes. This method was particularly useful in providing evidence for or against vertical transmission of a given clone of this microorganism, as well as for relapsing or reinfection in related cases, and suggested clonal relatedness between unrelated S. agalactiae isolates associated with some invasive infections. Thus, this simple methodology represents a suitable tool for the epidemiologic study of S. agalactiae infections.

Asunto(s)

Variación Genética , Técnica del ADN Polimorfo Amplificado Aleatorio , Infecciones Estreptocócicas/virología , Streptococcus agalactiae/genética , Secuencia de Bases , Cartilla de ADN , ADN Bacteriano/química , ADN Bacteriano/aislamiento & purificación , Genotipo , Humanos , Reacción en Cadena de la Polimerasa/métodos , Serotipificación , Streptococcus agalactiae/clasificación , Streptococcus agalactiae/aislamiento & purificación

RESUMEN

Epidemiological studies of Streptococcus agalactiae strains have been limited by the lack of sensitive and discriminatory methods for comparing clinical isolates. Serotyping, albeit a widely used methodology, has been shown to possess low capability to distinguish between epidemiologically related and unrelated isolates. We have employed here a random amplification of polymorphic DNA (RAPD) assay, using degenerate oligonucleotides as primers, to characterize S. agalactiae isolates from related or unrelated clinical samples. Epidemiologically-related isolates (mother-infant pairs) showed identical profiles by this methodology. On the contrary, 12 epidemiologically-unrelated isolates (classified into 5 different serotypes) resulted in 11 distinct RAPD patterns. This suggests that the proposed modified RAPD assay provides a highly discriminatory tool for the analysis of genomic diversity among isolates from pathogenic organisms.

Asunto(s)

Técnica del ADN Polimorfo Amplificado Aleatorio , Streptococcus agalactiae/aislamiento & purificación , Cartilla de ADN , Femenino , Genoma Bacteriano , Humanos , Recién Nacido , Reacción en Cadena de la Polimerasa , Embarazo , Serotipificación , Streptococcus agalactiae/clasificación , Streptococcus agalactiae/genética

RESUMEN

Epidemiological studies of Streptococcus agalactiae strains have been limited by the lack of sensitive and discriminatory methods for comparing clinical isolates. Serotyping, albeit a widely used methodology, has been shown to possess low capability to distinguish between epidemiologically related and unrelated isolates. We have employed here a random amplification of polymorphic DNA (RAPD) assay, using degenerate oligonucleotides as primers, to characterize S. agalactiae isolates from related or unrelated clinical samples. Epidemiologically-related isolates (mother-infant pairs) showed identical profiles by this methodology. On the contrary, 12 epidemiologically-unrelated isolates (classified into 5 different serotypes) resulted in 11 distinct RAPD patterns. This suggests that the proposed modified RAPD assay provides a highly discriminatory tool for the analysis of genomic diversity among isolates from pathogenic organisms.