[Distribution of capsular types and antimicrobial susceptibility of Streptococcus agalactiae causing infections in Argentina]. / Distribución de tipo capsular y sensibilidad antimicrobiana de Streptococcus agalactiae productores de infecciones en Argentina.

Streptococcus agalactiae is an endogenous bacterium that has emerged in the last 20 years as an etiological agent in both neonatal and perinatal infections, and in immunocompromised patients. The differentiation of the capsular polysaccharide, the presence of surface proteins c, X, R, and molecular methods allow classification in serotypes and genotypes. This identification is a useful tool for epidemiological purposes and virulence studies in this bacterium. The objective of this work was to study the serotypes and the antimicrobial susceptibility of isolates recovered from invasive diseases in different areas of Argentina. In the analyzed sample a fair predominance of Ia and III serotypes was recovered, followed by II and IV serotypes. All the isolates were found to be sensitive to penicillin. A 6% of resistance to erythromycin and a 4.5% to clindamycin were detected. In three of the isolates, constitutive MLS phenotype (resistance to macrolides, lincosamins and streptogramins) was founded, while in the remaining one, inducible MLS phenotype was detected. These results stress the importance of conducting a surveillance of the prevalent serotypes in our country with the goal of future prevention of this disease with an effective vaccine. The knowledge of the antimicrobial susceptibility profile will be also important to obtain therapeutic success in the treatment.

Distribución de tipo capsular y sensibilidad antimicrobiana de Streptococcusagalactiae productores de infecciones en Argentina / Distribution of capsular types and antimicrobial susceptibility of Streptococcus agalactiae causing infections in Argentina

Streptococcus agalactiae es una bacteria colonizante que ha emergido en los últimos años como causante de infecciones neonatales, perinatales y en pacientes con compromiso inmunológico. La caracterización del polisacárido capsular, de las proteínas de superficie (c, X, R), así como el análisis de marcadores moleculares, permiten su clasificación en serotipos y genotipos. Esto resulta de utilidad para fines epidemiológicos y para estudios de virulencia de la bacteria. El objetivo de este trabajo fue conocer los serotipos prevalentes y la sensibilidad antimicrobiana de aislamientos provenientes de procesos infecciosos en pacientes de distintas zonas de Argentina. En la muestra analizada se obtuvo predominio de los serotipos Ia y III, seguido de II y IV. Todas las cepas resultaron sensibles a penicilina. Se observó 6% de resistencia a eritromicina y 4,5% a clindamicina. En 3 de las cepas se detectó fenotipo MLS (resistencia a macrólidos, lincosaminas y estreptograminas) constitutiva y en una cepa, resistencia MLS inducible. Los resultados logrados en este estudio destacan la importancia de efectuar un relevamiento de los serotipos más frecuentes en nuestro país en vistas a la prevención de esta infección con una vacuna que realmente sea eficaz, como así también el conocimiento de la sensibilidad antimicrobiana para lograr éxito terapéutico en los tratamientos.

Streptococcus agalactiae is an endogenous bacterium that has emerged in the last 20 years as an etiological agent in both neonatal and perinatal infections, and in immunocompromised patients. The differentiation of the capsular polysaccharide, the presence of surface proteins c, X, R, and molecular methods allow classification in serotypes and genotypes. This identification is a useful tool for epidemiological purposes and virulence studies in this bacterium. The objective of this work was to study the serotypes and the antimicrobial susceptibility of isolates recovered from invasive diseases in different areas of Argentina. In the analyzed sample a fair predominance of Ia and III serotypes was recovered, followed by II and IV serotypes. All the isolates were found to be sensitive to penicillin. A 6% of resistance to erythromycin and a 4.5% to clindamycin were detected. In three of the isolates, constitutive MLS phenotype (resistance to macrolides, lincosamins and streptogramins) was founded, while in the remaining one, inducible MLS phenotype was detected. These results stress the importance of conducting a surveillance of the prevalent serotypes in our country with the goal of future prevention of this disease with an effective vaccine. The knowledge of the antimicrobial susceptibility profile will be also important to obtain therapeutic success in the treatment.

Distribución de tipo capsular y sensibilidad antimicrobiana de Streptococcus agalactiae productores de infecciones en Argentina. / [Distribution of capsular types and antimicrobial susceptibility of Streptococcus agalactiae causing infections in Argentina]

Streptococcus agalactiae is an endogenous bacterium that has emerged in the last 20 years as an etiological agent in both neonatal and perinatal infections, and in immunocompromised patients. The differentiation of the capsular polysaccharide, the presence of surface proteins c, X, R, and molecular methods allow classification in serotypes and genotypes. This identification is a useful tool for epidemiological purposes and virulence studies in this bacterium. The objective of this work was to study the serotypes and the antimicrobial susceptibility of isolates recovered from invasive diseases in different areas of Argentina. In the analyzed sample a fair predominance of Ia and III serotypes was recovered, followed by II and IV serotypes. All the isolates were found to be sensitive to penicillin. A 6

of resistance to erythromycin and a 4.5

to clindamycin were detected. In three of the isolates, constitutive MLS phenotype (resistance to macrolides, lincosamins and streptogramins) was founded, while in the remaining one, inducible MLS phenotype was detected. These results stress the importance of conducting a surveillance of the prevalent serotypes in our country with the goal of future prevention of this disease with an effective vaccine. The knowledge of the antimicrobial susceptibility profile will be also important to obtain therapeutic success in the treatment.

Phenotypic and genotypic study of Streptococcus agalactiae in vagina of pregnant women in Argentina.

Streptococcus agalactiae (GBS) is a leading cause of serious neonatal infection. In this study we determine the prevalence, serotype distribution and genomic diversity of GBS in vagina of pregnant women. Vaginal swabs of 531 pregnant women were cultured on Columbia Agar Base Blood, GBS Agar Base and Todd Hewitt Broth. GBS were characterized by group and type-specific agglutination. Genomic polymorphism was studied by random amplification of DNA (RAPD). Seventeen patients (3.2%) were positive for GBS, resulting serotype III the most frequent. RAPD detected 16 different RAPD profiles from 21 GBS studied, revealing a good discriminatory power. In this sense, this method showed different genotype from GBS serotype III recovered from successive samples of two patients, suggesting reinfection. In conclusion, the combination of RAPD and serotyping appear promising for epidemiological studies. Finally, findings of reinfection after therapy during pregnancy, led us to suggest performing prenatal GBS screening and intrapartum prophylaxis in order to reduce neonatal risk.

Phenotypic and genotypic study of Streptococcus agalactiae in vagina of pregnant women in Argentina.

Streptococcus agalactiae (GBS) is a leading cause of serious neonatal infection. In this study we determine the prevalence, serotype distribution and genomic diversity of GBS in vagina of pregnant women. Vaginal swabs of 531 pregnant women were cultured on Columbia Agar Base Blood, GBS Agar Base and Todd Hewitt Broth. GBS were characterized by group and type-specific agglutination. Genomic polymorphism was studied by random amplification of DNA (RAPD). Seventeen patients (3.2

) were positive for GBS, resulting serotype III the most frequent. RAPD detected 16 different RAPD profiles from 21 GBS studied, revealing a good discriminatory power. In this sense, this method showed different genotype from GBS serotype III recovered from successive samples of two patients, suggesting reinfection. In conclusion, the combination of RAPD and serotyping appear promising for epidemiological studies. Finally, findings of reinfection after therapy during pregnancy, led us to suggest performing prenatal GBS screening and intrapartum prophylaxis in order to reduce neonatal risk.

Genomic diversity among Streptococcus agalactiae isolates detected by a degenerate oligonucleotide-primed amplification assay.

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.

Characterization of clinical isolates of Streptococcus agalactiae by random amplified polymorphic DNA using degenerate oligonucleotides.

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.

Characterization of clinical isolates of Streptococcus agalactiae by random amplified polymorphic DNA using degenerate oligonucleotides.

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.

[Hemagglutination patterns of uropathogenic Escherichia coli]. / Patrones de hemoaglutinación de cepas de Escherichia coli uropatogénicas.

An hemagglutination (HA) type system has been applied to demonstrate mannose sensitive (MS) and mannose resistant (MR) hemagglutination produced by Escherichia coli isolated from urinary tract infections. Hemagglutination types were obtained by the agglutination of different species of red cells -human, bovine, chicken and guinea pig- suspended in buffer phosphate (PBS), with and without mannose, with E. coli cells grown in CFA agar (Casamino acid 10 g, yeast extract 15 g, sodium chloride 2.5 g, potassium phosphate 8.7 g, magnesium sulfate 0.5 g, manganese chloride 0.005 g, agar 20 g). Salting out (hydrophobicity) and yeast agglutination assays were performed for a complete evaluation of results. The applicability of this system was based on the dates exhibited in Table 1. A significant proportion (45%) of the uropathogenic Escherichia coli strains showed RNNN HA patterns, and (16%) NNSS, and (15%) SNSS were also considered important. The application of this hemagglutination system on this kind of strains allowed the evaluation of the different types of hemagglutination and their relation with colonization capacity.

Patrones de hemoaglutinación de cepas de Escherichia coli uropatogénicas. / [Hemagglutination patterns of uropathogenic Escherichia coli]

An hemagglutination (HA) type system has been applied to demonstrate mannose sensitive (MS) and mannose resistant (MR) hemagglutination produced by Escherichia coli isolated from urinary tract infections. Hemagglutination types were obtained by the agglutination of different species of red cells -human, bovine, chicken and guinea pig- suspended in buffer phosphate (PBS), with and without mannose, with E. coli cells grown in CFA agar (Casamino acid 10 g, yeast extract 15 g, sodium chloride 2.5 g, potassium phosphate 8.7 g, magnesium sulfate 0.5 g, manganese chloride 0.005 g, agar 20 g). Salting out (hydrophobicity) and yeast agglutination assays were performed for a complete evaluation of results. The applicability of this system was based on the dates exhibited in Table 1. A significant proportion (45

) of the uropathogenic Escherichia coli strains showed RNNN HA patterns, and (16

) NNSS, and (15

) SNSS were also considered important. The application of this hemagglutination system on this kind of strains allowed the evaluation of the different types of hemagglutination and their relation with colonization capacity.

Patrones de hemoaglutinación de cepas de Escherichia coli uropatogénicas / [Hemagglutination patterns of uropathogenic Escherichia coli]

An hemagglutination (HA) type system has been applied to demonstrate mannose sensitive (MS) and mannose resistant (MR) hemagglutination produced by Escherichia coli isolated from urinary tract infections. Hemagglutination types were obtained by the agglutination of different species of red cells -human, bovine, chicken and guinea pig- suspended in buffer phosphate (PBS), with and without mannose, with E. coli cells grown in CFA agar (Casamino acid 10 g, yeast extract 15 g, sodium chloride 2.5 g, potassium phosphate 8.7 g, magnesium sulfate 0.5 g, manganese chloride 0.005 g, agar 20 g). Salting out (hydrophobicity) and yeast agglutination assays were performed for a complete evaluation of results. The applicability of this system was based on the dates exhibited in Table 1. A significant proportion (45

) of the uropathogenic Escherichia coli strains showed RNNN HA patterns, and (16

) NNSS, and (15

) SNSS were also considered important. The application of this hemagglutination system on this kind of strains allowed the evaluation of the different types of hemagglutination and their relation with colonization capacity.