title: Prevalence of antimicrobial resistant Streptococcus pneumoniae serotype 11A isolates in Korea, during 2004-2013, due to the increase of multidrug-resistant clone, CC166.
abstract: Since the introduction of the pneumococcal conjugate vaccine (PCV7) in Korea in 2003, the proportion of non-vaccine serotypes has increased. Among non-vaccine serotypes, serotype 11A is highly prevalent in Korea. We investigated the prevalence and characteristics of Streptococcus pneumoniae serotype 11A isolates in a Korean tertiary-care hospital, during 2004-2013. A total of 1579 non-duplicate clinical S. pneumoniae isolates, collected from 2004 to 2013, were included in this study. Serotype was determined by the capsular Quellung method, and in vitro susceptibility testing was performed by broth microdilution method. Multilocus sequence typing was performed to determine the genotypes of the S. pneumoniae isolates. We identified 90 serotype 11A isolates (5.7%). During this period, the proportion of serotype 11A has increased from 3.2% up to 13.2% (in 2012). Among the serotype 11A isolates, two main clonal complexes (CCs), CC166 and CC99, were identified. The increase of serotype 11A was mainly due to the increase of CC166 isolates, which have high antimicrobial resistance rates. In addition, we identified that 14 isolates, belonging to ST8279, ST9875, and ST3598 of CC166, were non-susceptible to all antimicrobial agents tested in this study. We identified the increase of S. pneumoniae serotype 11A in Korea, which mainly due to the expansion of a resistant clonal group, CC166.
authors.affiliation: Asia Pacific Foundation for Infectious Diseases (APFID), Seoul, South Korea.
authors.forename: Jin Yang
authors.initials: JY
authors.lastname: Baek
authors.affiliation: Asia Pacific Foundation for Infectious Diseases (APFID), Seoul, South Korea.
authors.forename: So Hyun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
authors.forename: Cheol-In
authors.initials: CI
authors.lastname: Kang
authors.affiliation: Asia Pacific Foundation for Infectious Diseases (APFID), Seoul, South Korea; Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
authors.forename: Doo-Ryeon
authors.initials: DR
authors.lastname: Chung
authors.affiliation: Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
authors.forename: Kyong Ran
authors.initials: KR
authors.lastname: Peck
authors.affiliation: Asia Pacific Foundation for Infectious Diseases (APFID), Seoul, South Korea; Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, South Korea. Electronic address: ksko@skku.edu.
authors.forename: Kwan Soo
authors.initials: KS
authors.lastname: Ko
authors.affiliation: Asia Pacific Foundation for Infectious Diseases (APFID), Seoul, South Korea; Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea. Electronic address: songjh@skku.edu.
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Song
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology; D003428:Cross Infection; D024901:Drug Resistance, Multiple, Bacterial; D049674:History, 21st Century; D006801:Humans; D008826:Microbial Sensitivity Tests; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000266:history / Q000382:microbiology*; D015995:Prevalence; D056910:Republic of Korea / Q000453:epidemiology; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000890:Anti-Infective Agents
keywords: CC166; Extensively drug-resistant (XDR); Pneumococci; ST8279