A Nationwide Outbreak of Invasive Pneumococcal Disease in Israel Caused by Streptococcus pneumoniae Serotype 2

Ron Dagan, Shalom Ben-Shimol, Rachel Benisty, Gili Regev-Yochay, Stephanie W. Lo, Stephen D. Bentley, Paulina A. Hawkins, Lesley McGee, Merav Ron, Noga Givon-Lavi, Lea Valinsky, Assaf Rokney

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND: Invasive pneumococcal disease (IPD) caused by Streptococcus pneumoniae serotype 2 (Sp2) is infrequent. Large-scale outbreaks were not been reported following pneumococcal conjugate vaccine (PCV) implementation. We describe a Sp2 IPD outbreak in Israel, in the PCV13 era, with focus on Sp2 population structure and evolutionary dynamics. METHODS: The data were derived from a population-based, nationwide active surveillance of IPD since 2009. PCV7/PCV13 vaccines were introduced in July 2009 and November 2010, respectively. Sp2 isolates were tested for antimicrobial susceptibility, multilocus sequence typing, and whole-genome sequencing (WGS) analysis. RESULTS: Overall, 170 Sp2 IPD cases were identified during 2009-2019; Sp2 increased in 2015 and caused 6% of IPD during 2015-2019, a 7-fold increase compared with 2009-2014. The outbreak was caused by a previously unreported molecular type (ST-13578), initially observed in Israel in 2014. This clone caused 88% of Sp2 during 2015-2019. ST-13578 is a single-locus variant of ST-1504, previously reported globally including in Israel. WGS analysis confirmed clonality among the ST-13578 population. Single-nucleotide polymorphism-dense regions support a hypothesis that the ST-13578 outbreak clone evolved from ST-1504 by recombination. All tested strains were penicillin-susceptible (minimum inhibitory concentration <0.06 μg/mL). The ST-13578 clone was identified almost exclusively (99%) in the Jewish population and was mainly distributed in 3 of 7 Israeli districts. The outbreak is still ongoing, although it began declining in 2017. CONCLUSIONS: To the best of our knowledge, this is the first widespread Sp2 outbreak since PCV13 introduction worldwide, caused by the emerging ST-13578 clone.

Original languageEnglish
Pages (from-to)e3768-e3777
JournalClinical Infectious Diseases
Volume73
Issue number11
DOIs
StatePublished - 6 Dec 2021

Keywords

  • Streptococcus pneumoniae serotype 2
  • invasive pneumococcal disease
  • outbreak
  • pneumococcal conjugate vaccine

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