The impact of pneumococcal conjugate vaccines on carriage of and disease caused by Streptococcus pneumoniae serotypes 6C and 6D in southern Israel.
The introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) followed by PCV13 resulted in a dramatic reduction in carriage and disease rates of Streptococcus pneumoniae (Sp) serotype 6B (Sp6B) and Sp6A. The structural modifications of the capsule of Sp6A and Sp6B to become Sp6C and Sp6D, respectively, raised a concern that eradication of Sp6A/Sp6B by PCV could be accompanied by an increase in Sp6C/Sp6D. This study examines the dynamics and clonal distribution of Sp6C/Sp6D relative to Sp6A/Sp6B during 1999-2014, pre- and post-PCV implementation. Sp were cultured from Blood/CSF and MEF of children <2 years, and from conjunctiva and nasopharynx of children <5 years. PCR was applied for Sp6C and Sp6D identification. Clonality was determined by PFGE and MLST. PCV introduction resulted in decreased carriage rates and conjunctivitis caused by serogroup 6 serotypes. Incidence of Sp6A, Sp6B and Sp6D in otitis media dropped gradually along with PCV7/13 introduction, whereas Sp6C rates increased in the PCV7 period and then decreased following PCV13 implementation. In invasive pneumococcal disease, complete elimination of serogroup 6 was found in the PCV era. Similar clonal composition was found for Sp6C and Sp6D pre- and post-PCV. We conclude that Sp6C and Sp6D do not act as replacement serotypes for Sp6A and Sp6B following vaccination with PCV13. The major Sp6C and Sp6D clones present pre-PCV persisted also post-PCV implementation, suggesting that these clones possess an advantage retained post-vaccination.
Pediatric Infectious Disease Unit, Soroka University Medical Center, Beer-Sheva, Israel; Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel. Electronic address: npurat@bgu.ac.il.
Nurith
N
Porat
Pediatric Infectious Disease Unit, Soroka University Medical Center, Beer-Sheva, Israel; Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Rachel
R
Benisty
Pediatric Infectious Disease Unit, Soroka University Medical Center, Beer-Sheva, Israel; Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Noga
N
Givon-Lavi
Pediatric Infectious Disease Unit, Soroka University Medical Center, Beer-Sheva, Israel; Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Ronit
R
Trefler
Pediatric Infectious Disease Unit, Soroka University Medical Center, Beer-Sheva, Israel; Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Ron
R
Dagan
D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D002675:Child, Preschool; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000627:therapeutic use*; D006801:Humans; D007557:Israel / Q000453:epidemiology; D058885:Multilocus Sequence Typing; D009305:Nasopharynx / Q000382:microbiology; D011008:Pneumococcal Infections / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000627:therapeutic use*; D011446:Prospective Studies; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification*
C538862:13-valent pneumococcal vaccine; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines
Multilocus sequence typing; Pulsed field gel electrophoresis; Serotype 6C; Serotype 6D; Streptococcus pneumoniae