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 Lin, J. Articles by Nahm, M. H. Search for Related Content PubMed PubMed Citation Articles by Lin, J. Articles by Nahm, M. H.

 Previous Article  |  Next Article 

Journal of Clinical Microbiology, February 2006, p. 383-388, Vol. 44, No. 2
0095-1137/06/$08.00+0     doi:10.1128/JCM.44.2.383-388.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Validation of a Multiplex Pneumococcal Serotyping Assay with Clinical Samples

Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama,¹ The WHO Collaborating Center for Reference and Research on Pneumococci, Statens Serum Institut, Copenhagen, Denmark,² Bacteriology Section, Adolfo Lutz Institute, Sao Paulo, Brazil,³ IOC/FIOCRUZ, Rio de Janeiro, Brazil,⁴ Department of Clinical Epidemiology, National Institute of Public Health, Cuernavaca, Mexico,⁵ Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama⁶

Received 12 October 2005/ Returned for modification 17 November 2005/ Accepted 6 December 2005

We have recently developed a rapid pneumococcal serotyping method called "multibead assay" (J. Yu et al., J. Clin. Microbiol. 43:156-162, 2005) based on a multiplexed immunoassay for capsular polysaccharides in lysates of pneumococcal cultures. The multibead assay can identify 36 serotypes (1, 2, 3, 4, 5, 6A, 6B, 7A/7F, 8, 9L/9N, 9V, 10A/10B/39/33C, 11A/11D/11F, 12A/12B/12F, 14, 15B/5C, 17F, 18C, 19A, 19F, 20, 22A/22F, 23F, and 33A/33F). More than 90% of the U.S. isolates express one of these serotypes (J. B. Robbins et al., J. Infect. Dis. 148:1136-1159, 1983). To validate the new assay, we examined 495 clinical isolates of pneumococci obtained in Brazil, Denmark, and Mexico. Pneumococci were serotyped by the Neufeld test in their countries of origin, and lysates of each strain were coded and mailed to the United States for the multibead assay at ambient temperature without any thermal protection. After breaking the code, 54 discrepancies (11% of samples) were noted, but 46 were due to nonreproducible technical problems or insufficient growth of the pneumococci. All of the isolates grew well for a second test, and therefore, the culture medium used for the multibead assay is adequate. The discrepancies persisted for eight isolates, involving the 6A, 11A, and 18C serotypes. Additional studies of the eight isolates showed that the discrepancies were due to differences in the reagents used in the multibead or Neufeld tests for these three serotypes. For instance, five isolates were typed as 6A with the Neufeld test but as nontypeable by the multibead assay. Selection of another new monoclonal antibody (Hyp6AG1) for the multibead assay resulted in all five discrepant isolates typing as 6A. This finding indicates the validity of the multibead assay and emphasizes the need to validate any new pneumococcal serotyping assay with a large number of clinical isolates from different locations. It also suggests the presence of serological subtypes among isolates expressing the 6A serotype.

This article has been cited by other articles:

• Yu, J., Carvalho, M. d. G. S., Beall, B., Nahm, M. H. (2008). A rapid pneumococcal serotyping system based on monoclonal antibodies and PCR. J Med Microbiol 57: 171-178 [Abstract] [Full Text]  
• Park, I. H., Park, S., Hollingshead, S. K., Nahm, M. H. (2007). Genetic Basis for the New Pneumococcal Serotype, 6C. Infect. Immun. 75: 4482-4489 [Abstract] [Full Text]  
• Inostroza, J., Illesca, V., Reydet, P., Vinet, A. M., Ossa, G., Munoz, S., Thompson, T., Sorensen, R. U. (2007). Ten-Year Surveillance of Pneumococcal Infections in Temuco, Chile: Implications for Vaccination Strategies. CVI 14: 660-664 [Abstract] [Full Text]  
• Park, I. H., Pritchard, D. G., Cartee, R., Brandao, A., Brandileone, M. C. C., Nahm, M. H. (2007). Discovery of a New Capsular Serotype (6C) within Serogroup 6 of Streptococcus pneumoniae. J. Clin. Microbiol. 45: 1225-1233 [Abstract] [Full Text]