Surface Protein Expression in Group B Streptococcal Invasive Isolates

Ferrieri, Patricia; Flores, Aurea E.

doi:10.1007/978-1-4899-1825-3_148

Cited by 45 publications

(58 citation statements)

References 12 publications

(26 reference statements)

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“…When assessed by various techniques, GBS is found not to belong to homogeneous serotype groups, as considerable variation is found at the genetic and protein levels (14,26). Genotypic methods, including pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST), have been used to genetically characterize and distinguish specific clones of GBS isolates (4,15,21,35).…”

Section: Streptococcus Agalactiae (Group B Streptococcus [Gbs]) Is a mentioning

confidence: 99%

Molecular Characterization of Nontypeable Group B Streptococcus

et al. 2006

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Traditionally, the capsular polysaccharide (CPS) antigen has been used to distinguish between the nine known serotypes of group B streptococcus (GBS) by classical antibody-antigen reactions. In this study, we used PCR for all CPSs and selected protein antigens, multilocus sequencing typing (MLST), and pulsed-field gel electrophoresis (PFGE) to molecularly characterize 92 clinical isolates identified as nontypeable (NT) by CPS-specific antibody-antigen reactivity. The PCR and MLST were performed on blinded, randomly numbered isolates. All isolates contained the cfb gene coding for CAMP factor. While most (56.5%) contained a single CPS-specific gene, 40 isolates contained either two or three CPS-specific genes. Type V CPS-specific gene was present in 66% of the isolates, and all serotypes except types IV, VII, and VIII were represented. Most (44.5%) of the isolates contained a single protein antigen gene (bca, bac, rib, alp1, or alp3), and the remaining isolates had multiple protein antigen genes. Of the 61 isolates that had the V CPS-specific gene, 48 (78.6%) had the alp3 gene. PFGE analysis classified the isolates into 21 profile groups, while MLST analysis divided the isolates into 16 sequence types. Forty-two (69%) of 61 isolates with the V CPS-specific gene were in PFGE profile group 4; 41 of these 42 were sequence type 1 by MLST. These data shed new light on the antigenic complexity of NT GBS isolates, information that can be valuable in the formulation of an effective GBS vaccine.

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Section: Streptococcus Agalactiae (Group B Streptococcus [Gbs]) Is a mentioning

confidence: 99%

Molecular Characterization of Nontypeable Group B Streptococcus

et al. 2006

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“…Group B streptococci (GBS) are generally known to be pathogenic for humans, particularly for newborn infants, but they are also recognized as a cause of bacteremia in parturient women, elderly people, and immunocompromised patients (2). At present, GBS strains are typed in reference laboratories around the world by use of typing schemes based on serotyping, followed, if necessary, by phage typing (3).…”

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“…The primary serologic test used for classification in the laboratories is the capillary precipitation test introduced by Lancefield in 1934 (5). This test is based on the presence of capsular antigens extracted with hot hydrochloric acid (HCl) and allows classification of GBS strains into nine serotypes (Ia, Ib, II, III, IV, V, VI, VII, and VIII) (2,3,7). Most GBS strains can be classified as belonging to one of these serotypes, but always a certain percentage of strains remains nontypeable (NT) (2,4).…”

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“…This test is based on the presence of capsular antigens extracted with hot hydrochloric acid (HCl) and allows classification of GBS strains into nine serotypes (Ia, Ib, II, III, IV, V, VI, VII, and VIII) (2,3,7). Most GBS strains can be classified as belonging to one of these serotypes, but always a certain percentage of strains remains nontypeable (NT) (2,4). We have observed that the normality of the HCl used in the extract antigen can affect the number of strains that are determined to be NT in surveillance studies.…”

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False-Negative Results in Typing of Group B Streptococci by the Standard Lancefield Antigen Extraction Method

2002

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Group B streptococci (GBS) are generally known to be pathogenic for humans, particularly for newborn infants, but they are also recognized as a cause of bacteremia in parturient women, elderly people, and immunocompromised patients (2). At present, GBS strains are typed in reference laboratories around the world by use of typing schemes based on serotyping, followed, if necessary, by phage typing (3). The primary serologic test used for classification in the laboratories is the capillary precipitation test introduced by Lancefield in 1934 (5). This test is based on the presence of capsular antigens extracted with hot hydrochloric acid (HCl) and allows classification of GBS strains into nine serotypes (Ia, Ib, II, III, IV, V, VI, VII, and VIII) (2, 3, 7). Most GBS strains can be classified as belonging to one of these serotypes, but always a certain percentage of strains remains nontypeable (NT) (2, 4). We have observed that the normality of the HCl used in the extract antigen can affect the number of strains that are determined to be NT in surveillance studies.Routinely, the microbiology departments of various institutions in Denmark submit GBS strains (confirmed to be such by pure culture) for typing in our facility (the Streptococcus Unit of the Statens Serum Institut). However, before we carry out the serotyping for a given strain, we always verify that it is a GBS strain by evaluating the strain visually on a blood-agar plate and by testing it with GBS antiserum by the Lancefield method.Of the 383 human isolates of GBS received at the Streptococcus Unit during the years 1997 to 2000, 154 were classified as serotype III. Of these, 103 isolates reacted with the specific antiserum when extracted with both 0.1 and 0.2 N HCl, and 51 isolates reacted only when extracted with 0.2 N HCl. A total of 26 of the isolates did not react when extracted with either HCl concentration. Based on this observation, we decided that, beginning in the year 2001, we would test all GBS isolates with both 0.1 and 0.2 N HCl to determine if we could reduce the number of NT GBS isolates. We had previously used only one extract concentration (0.2 N HCl) for typing GBS isolates.The antisera used for typing the GBS isolates as belonging generally to group B and more specifically to one of the serotypes (Ia to VIII) were produced at the Streptococcus Unit. The Lancefield extracts used as controls were based on reference strains of GBS serotypes Ia to VIII, as well as of group B, that were obtained within the Streptococcus Unit, which serves as a national reference center for streptococci. A modified version of the Lancefield method (which modification is used as the standard serotyping method in the Streptococcus Unit) was performed as follows. A freeze-dried culture of GBS was suspended into serum broth. From this suspension, a control for purity was made by plating a droplet onto a 5% horse blood-agar plate. The agar plate was incubated at 36°C overnight. The next day, a few colonies from the agar plate were added to 5 ml of glucose broth...

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“…GBS are serotyped on the basis of their capsular polysaccharide, of which nine different serotypes have been described (10,15). The classical serotypes Ia, Ib, II, and III are the predominant cause of disease in neonates.…”

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Clonal Relationship between U.S. and French Serotype V Group B Streptococcus Isolates

et al. 2001

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We examined the genetic diversity of serotype V group B streptococcus (GBS) isolates in the Paris area and compared them with the predominant American serotype V clone. Pulsed-field gel electrophoresis yielded 11 patterns for 64 French GBS. One pattern was obtained with 60% of the isolates tested and was indistinguishable from that of the predominant American clone.Group B streptococci (GBS) are the main cause of severe infection in both infants and adults (2,20,21). GBS are serotyped on the basis of their capsular polysaccharide, of which nine different serotypes have been described (10, 15). The classical serotypes Ia, Ib, II, and III are the predominant cause of disease in neonates. Recently, serotype V GBS have emerged as a new cause of GBS infection or colonization in children and adults (13,18,19). Indeed, population-based surveillance of GBS in the 1990s indicated that serotype V was responsible for 10 to 15% of neonatal GBS infections in the United States (7,13,17) and was the most common serotype isolated from nonpregnant adults with invasive disease (13). Moreover, data from the Centers for Disease Control and Prevention (Atlanta, Ga.) have shown the emergence of a serotype V clonal type (8).In France, too, recent studies point to a significant shift in the distribution of GBS serotypes, with serotype V emerging as one of the major serotypes recovered from neonates (1,11,16).We examined the genetic diversity of French serotype V GBS clinical isolates in the Paris area and compared them with the predominant American clone.We studied a collection of 64 serotype V GBS isolates recovered between January 1998 and January 2000 in the Paris area. The isolates were obtained from genital specimens from pregnant women (n ϭ 30) or from gastric fluid or ear specimens from colonized or infected newborns (n ϭ 34). GBS isolates were confirmed at the species level by standard laboratory methods and were serotyped with a commercial latex agglutination kit (Streptex; Murex Diagnostics UK). The isolates were stored in Todd-Hewitt broth with 20% glycerol at Ϫ80°C until further analysis was done.Pulsed-field gel electrophoresis (PFGE) of serotype V GBS strains was performed as previously described (12). SmaI restriction enzyme chromosomal digests were separated with a Bio-Rad contour-clamped homogenous electric field mapper with a switch time of 0.85 to 35.38 s for 22 h and 35 min at a 120°angle with a voltage gradient of 6 V/cm at 14°C. The DNA size standard was a lambda DNA ladder (Bio-Rad). The gels were stained with ethidium bromide and photographed under UV light. PFGE banding patterns were compared visually. Strains were considered genetically distinguishable if their restriction patterns differed by three or more bands (24). Banding patterns were also compared using a computer system (Biocapt; Vilber-Lourmat) and whole-band analyzer software (Biogène; Vilber-Lourmat). Cluster analysis (unweighted pair group average) was used to calculate similarity and dissimilarity among GBS isolates. A difference was considered si...

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Surface Protein Expression in Group B Streptococcal Invasive Isolates

Cited by 45 publications

References 12 publications

Molecular Characterization of Nontypeable Group B Streptococcus

Molecular Characterization of Nontypeable Group B Streptococcus

False-Negative Results in Typing of Group B Streptococci by the Standard Lancefield Antigen Extraction Method

Clonal Relationship between U.S. and French Serotype V Group B Streptococcus Isolates

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