Streptococcus pneumoniae Serotype 6D, South Korea | CDC EID

EID Journal Home > Volume 16, Number 11–November 2010
Volume 16, Number 11–November 2010
Dispatch
Prevalence and Genetic Structures of Streptococcus pneumoniae Serotype 6D, South Korea

Eun Hwa Choi, Hoan Jong Lee, Comments to Author Eun Young Cho, Chi Eun Oh, Byung Wook Eun, Jina Lee, and Min Ja Kim
Author affiliations: Seoul National University Children's Hospital, Seoul, South Korea (E.H. Choi, H.J. Lee, E.Y. Cho, C.E. Oh, B.W. Eun); Seoul National University College of Medicine, Seoul (E.H. Choi, H.J. Lee); Kosin University College of Medicine, Busan, South Korea (C.E. Oh); Gachon University Gil Hospital, Incheon, South Korea (B.W. Eun); Seoul National University Bundang Hospital, Seongnam, South Korea (J. Lee); and Korea University College of Medicine, Seoul (M.J. Kim)

Suggested citation for this article

Abstract
To determine prevalence and genetic structures of new serotype 6D strains of pneumococci, we examined isolates from diverse clinical specimens in South Korea during 1991–2008. Fourteen serotype 6D strains accounted for 10.4% of serogroup 6 pneumococci from blood, sputum, nasopharynx, and throat samples. Serotype 6D strains consisted of 3 sequence types.

Streptococcus pneumoniae is a common cause of invasive infection in infants, children, and adults. The polysaccharide capsule of S. pneumoniae is the major virulence factor that protects the organism from host phagocytosis (1). Recently, 2 new serotypes of serogroup 6 pneumococci, 6C and 6D, were genetically and biochemically characterized (2,3). Serotype 6C was identified in 2007 on the basis of its distinct binding patterns with 2 monoclonal antibodies; serotype 6C had previously been typed as 6A according to the standard quellung reaction. Serotype 6C produces glucose in the place of galactose in the 6A capsular polysaccharide and has the wciNβ gene, which is ≈200 bp shorter than the corresponding wciN gene in 6A (2,4). After the discovery and characterization of 6C through genetic and biochemical studies, a new experimental serotype, 6X1 (later named 6D), was created by mutating the critical nucleotide in the wciP gene of the 6C capsule gene locus or by inserting the wciNβ gene into the 6B capsule gene locus (3). However, this putative serotype, 6D was thought to not exist in nature until recently, when 2 studies found 6D strains in nasopharyngeal aspirates from children in Fiji during 2004–2007 (5) and in 2 nasopharyngeal aspirates from children in South Korea in 2008 (6). Although serotype 6C has only recently been described, several studies indicate that serotype 6C pneumococci have been circulating in many countries, including the United States, the Netherlands, Australia, Israel, and South Africa (7–10). However, reports of naturally occurring serotype 6D pneumococci are limited.

We investigated the prevalence of serotypes 6C and 6D in 2 collections of pneumococci isolated from clinical specimens in South Korea. We compared the genetic diversity and antimicrobial drug susceptibility patterns of the 4 serotypes, 6A, 6B, 6C, and 6D.

full-text:
Streptococcus pneumoniae Serotype 6D, South Korea | CDC EID

Suggested Citation for this Article

Choi EH, Lee HJ, Cho EY, Oh CE, Eun BW, Lee J, et al. Prevalence and genetic structures of Streptococcus pneumoniae serotype 6D, South Korea. Emerg Infect Dis [serial on the Internet]. 2010 Nov [date cited]. http://www.cdc.gov/EID/content/16/11/1751.htm

DOI: 10.3201/eid1611.100941