This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Amundson, N. R. Articles by Ferrieri, P. Search for Related Content PubMed PubMed Citation Articles by Amundson, N. R. Articles by Ferrieri, P.

DNA Macrorestriction Analysis of Nontypeable Group B Streptococcal Isolates: Clonal Evolution of Nontypeable and Type V Isolates

Departments of Laboratory Medicine and Pathology and Pediatrics, University of Minnesota Medical School, Minneapolis, Minnesota,¹ Department of Obstetrics, Gynecology, and Reproductive Sciences, Magee Women's Hospital and University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania,² Departments of Pediatrics and Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas³

Received 1 September 2004/ Returned for modification 4 October 2004/ Accepted 12 October 2004

Group B streptococci (GBS) are serotyped according to capsular polysaccharide (CPS) type (Ia to VIII); an isolate is classified as nontypeable (NT) if no detectable CPS is found. Surface-localized protein antigens (, ß, R1, and R4) serve as additional markers to classify GBS isolates, which is particularly useful since NT isolates often express one or more of these proteins. To compare genetic resemblance among isolates with similar protein profiles, we studied 58 NT isolates digested with the SmaI macrorestriction enzyme prior to pulsed-field gel electrophoresis (PFGE). Of these 58, 15.5% expressed only, 20.7% expressed +ß, 15.5% expressed R4, and 25.8% expressed R1,R4, while 22.4% of the isolates expressed no detectable proteins. The largest PFGE profile group, with 48% of the isolates, was group 4, composed primarily of isolates that expressed R1,R4 or no proteins. The second most common profiles were 3 and 32, each with 13.8% of the isolates. Since NT isolates in profile group 4 were highly related to type V isolates, as demonstrated by PFGE profiles, we investigated 45 type V isolates. Two-thirds of the type V isolates within profile group 4 were classified into subgroup 4a, compared to 28.2% of 39 NT isolates. Only 11% of the V/R1,R4 isolates were identical to the prototype group 4 profile, in contrast to 75% of the NT/R1,R4 isolates. A shift of type V isolates into profile 4 subgroups may be indicative of a genetic change over time. PFGE is a valuable approach for comparison of GBS isolate relatedness and for monitoring of NT and typeable GBS isolates for potential clonal divergence.

This article has been cited by other articles:

• Slotved, H.-C., Kong, F., Lambertsen, L., Sauer, S., Gilbert, G. L. (2007). Serotype IX, a Proposed New Streptococcus agalactiae Serotype. J. Clin. Microbiol. 45: 2929-2936 [Abstract] [Full Text]  
• Gherardi, G., Imperi, M., Baldassarri, L., Pataracchia, M., Alfarone, G., Recchia, S., Orefici, G., Dicuonzo, G., Creti, R. (2007). Molecular Epidemiology and Distribution of Serotypes, Surface Proteins, and Antibiotic Resistance among Group B Streptococci in Italy. J. Clin. Microbiol. 45: 2909-2916 [Abstract] [Full Text]  
• Poyart, C., Tazi, A., Reglier-Poupet, H., Billoet, A., Tavares, N., Raymond, J., Trieu-Cuot, P. (2007). Multiplex PCR Assay for Rapid and Accurate Capsular Typing of Group B Streptococci. J. Clin. Microbiol. 45: 1985-1988 [Abstract] [Full Text]  
• Ramaswamy, S. V., Ferrieri, P., Flores, A. E., Paoletti, L. C. (2006). Molecular characterization of nontypeable group B streptococcus.. J. Clin. Microbiol. 44: 2398-2403 [Abstract] [Full Text]