Reduction of antimicrobial resistant pneumococci seven years after introduction of pneumococcal vaccine in Iceland

PLoS One. 2020 Mar 17;15(3):e0230332. doi: 10.1371/journal.pone.0230332. eCollection 2020.

Abstract

Background: Penicillin non-susceptible (PNSP) and multi-resistant pneumococci have been prevalent in Iceland since early nineties, mainly causing problems in treatment of acute otitis media. The 10-valent protein conjugated pneumococcal vaccine (PHiD-CV) was introduced into the childhood vaccination program in 2011. The aim of the study was to investigate the changes in antimicrobial susceptibility and serotype distribution of penicillin non-susceptible pneumococci (PNSP) in Iceland 2011-2017.

Methods and findings: All pneumococcal isolates identified at the Landspítali University Hospital in 2011-2017, excluding isolates from the nasopharynx and throat were studied. Susceptibility testing was done according to the EUCAST guidelines using disk diffusion with chloramphenicol, erythromycin, clindamycin, tetracycline, trimethoprim/sulfamethoxazole and oxacillin for PNSP screening. Penicillin and ceftriaxone minimum inhibitory concentrations (MIC) were measured for oxacillin resistant isolates using the E-test. Serotyping was done using latex agglutination and/or multiplex PCR. The total number of pneumococcal isolates that met the study criteria was 1,706, of which 516 (30.2%) were PNSP, and declining with time. PNSP isolates of PHiD-CV vaccine serotypes (VT) were 362/516 (70.2%) declining with time, 132/143 (92.3%) in 2011 and 17/54 (31.5%) in 2017. PNSP were most commonly of serotype 19F, 317/516 isolates declining with time, 124/143 in 2011 and 15/54 in 2017. Their number decreased in all age groups, but mainly in the youngest children. PNSP isolates of non PHiD-CV vaccine serotypes (NVT) were 154/516, increasing with time, 11/14, in 2011 and 37/54 in 2017. The most common emerging NVTs in 2011 and 2017 were 6C, 1/143 and 10/54 respectively.

Conclusions: PNSP of VTs have virtually disappeared from children with pneumococcal diseases after the initiation of pneumococcal vaccination in Iceland and a clear herd effect was observed. This was mainly driven by a decrease of PNSP isolates belonging to a serotype 19F multi-resistant lineage. However, emerging multi-resistant NVT isolates are of concern.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Anti-Bacterial Agents / therapeutic use
  • Carrier State / diagnosis
  • Carrier State / epidemiology
  • Carrier State / microbiology*
  • Child, Preschool
  • Drug Resistance, Multiple, Bacterial
  • Female
  • Health Plan Implementation / organization & administration
  • Health Plan Implementation / statistics & numerical data
  • Humans
  • Iceland / epidemiology
  • Immunization Programs / organization & administration
  • Immunization Programs / statistics & numerical data
  • Immunization Schedule
  • Infant
  • Infant, Newborn
  • Male
  • Microbial Sensitivity Tests
  • Otitis Media
  • Penicillin Resistance
  • Pharynx / microbiology
  • Pneumococcal Infections / epidemiology
  • Pneumococcal Infections / microbiology
  • Pneumococcal Infections / prevention & control*
  • Pneumococcal Vaccines / therapeutic use*
  • Program Evaluation
  • Serotyping / statistics & numerical data
  • Streptococcus pneumoniae / drug effects
  • Streptococcus pneumoniae / immunology
  • Streptococcus pneumoniae / isolation & purification*

Substances

  • Anti-Bacterial Agents
  • PHiD-CV vaccine
  • Pneumococcal Vaccines

Grants and funding

This work is an investigator-initiated study that was supported by grants from: - The Landspítali University Hospital Research Fund (MÁH) https://www.landspitali.is - GlaxoSmithKline Biologicals SA (KGK, HE, ÁH), https://www.gsk.com The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.