title: Frequency and molecular characterization of invasive isolates of Streptococcus pneumoniae serotypes 6C and 6D in Colombia.
abstract: BACKGROUND
  Serogroup 6 of Streptococcus pneumoniae initially consisted of the 6A and 6B serotypes, but in recent years, the 6C and 6D serotypes were reported. The aim of this study was to determine the frequency and molecular characterization of invasive S. pneumoniae isolates serotypes 6C and 6D in Colombia, from 1994 to 2013.
  
  
  METHODS
  All the isolates recovered during the surveillance from 1994 to 2013, and identified as 6A or 6B, were re-tested to detect the serotypes 6C and 6D. The serotyping was performed using the Quellung reaction and PCR. The susceptibility testing was performed on penicillin, erythromycin, ceftriaxone, trimethoprim/sulfamethoxazole, chloramphenicol, tetracycline and vancomycin. Molecular typing was performed using pulsed-field gel electrophoresis and multilocus sequence typing.
  
  
  RESULTS
  From a total of 271 and 350 isolates serotyped previously as serotypes 6A and 6B, 61 (22.5%) and 15 (4.3%) were recognized as 6C and 6D, respectively. Isolates presented with low resistance to antimicrobials. Serotype 6C isolates were mainly associated with ST9007 (42.6%) and ST9008 (19.7%), and serotype 6D isolates with ST1135 (80%).
  
  
  CONCLUSIONS
  This study showed the circulation of serotype 6C and 6D in Colombia between 1994 and 2013, information that is important to determine the dynamics of these recently described serotypes.
authors.affiliation: Grupo de Microbiología, Instituto Nacional de Salud, Colombia.
authors.forename: Eliana Liseth
authors.initials: EL
authors.lastname: Parra
authors.affiliation: Grupo de Microbiología, Instituto Nacional de Salud, Colombia.
authors.forename: Carolina
authors.initials: C
authors.lastname: Duarte
authors.affiliation: Grupo de Microbiología, Instituto Nacional de Salud, Colombia.
authors.forename: Karina
authors.initials: K
authors.lastname: Rodríguez
authors.affiliation: Grupo de Microbiología, Instituto Nacional de Salud, Colombia.
authors.forename: Olga
authors.initials: O
authors.lastname: Sanabria
authors.affiliation: Grupo de Microbiología, Instituto Nacional de Salud, Colombia. Electronic address: jmoreno@ins.gov.co.
authors.forename: Jaime
authors.initials: J
authors.lastname: Moreno
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016667:Bacterial Capsules / Q000235:genetics; D015373:Bacterial Typing Techniques; D003105:Colombia / Q000453:epidemiology; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D011159:Population Surveillance; D065288:Serogroup; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents
keywords: Epidemiología molecular; Molecular epidemiology; Serotipos; Serotypes; Streptococcus pneumoniae; Surveillance; Vigilancia