RESUMEN
Eighty-six carbapenem non-susceptible Pseudomonas aeruginosa isolates collected in the National Institute of Respiratory Diseases of Mexico City were screened for the presence of metallo-beta-lactamase (MBL) activity using both E-test strips and a microbiological assay with EDTA-imipenem. Genomic comparisons and sequence analyses conducted with these isolates revealed the presence of bla(VIM-2) in two clonally related isolates, and bla(IMP-15) in a clonally unrelated isolate. Both genes were found to be carried by class 1 integrons, and bla(IMP-15) was additionally present on a broad host-range plasmid. This is the first report of co-existing P. aeruginosa strains producing different MBLs in a Mexican hospital, highlighting the necessity of appropriate surveillance to prevent dissemination of carbapenem resistance.
Asunto(s)
Proteínas Bacterianas/biosíntesis , Infecciones por Pseudomonas/microbiología , Pseudomonas aeruginosa/enzimología , Pseudomonas aeruginosa/aislamiento & purificación , beta-Lactamasas/biosíntesis , Proteínas Bacterianas/genética , ADN Bacteriano/genética , Hospitales , Humanos , Integrones , México , Pruebas de Sensibilidad Microbiana/métodos , Plásmidos , beta-Lactamasas/genéticaRESUMEN
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 & purificaciónRESUMEN
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/genéticaRESUMEN
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.