Molecular Analysis of Rising Fluoroquinolone Resistance in Belgian Non-Invasive Streptococcus pneumoniae Isolates (1995-2014)

PLoS One. 2016 May 26;11(5):e0154816. doi: 10.1371/journal.pone.0154816. eCollection 2016.

Abstract

We present the results of a longitudinal surveillance study (1995-2014) on fluoroquinolone resistance (FQ-R) among Belgian non-invasive Streptococcus pneumoniae isolates (n = 5,602). For many years, the switch to respiratory fluoroquinolones for the treatment of (a)typical pneumonia had no impact on FQ-R levels. However, since 2011 we observed a significant decrease in susceptibility towards ciprofloxacin, ofloxacin and levofloxacin with peaks of 9.0%, 6.6% and 3.1% resistant isolates, respectively. Resistance to moxifloxacin arised sporadically, and remained <1% throughout the entire study period. We observed classical topoisomerase mutations in gyrA (n = 25), parC (n = 46) and parE (n = 3) in varying combinations, arguing against clonal expansion of FQ-R. The impact of recombination with co-habiting commensal streptococci on FQ-R remains marginal (10.4%). Notably, we observed that a rare combination of DNA Gyrase mutations (GyrA_S81L/GyrB_P454S) suffices for high-level moxifloxacin resistance, contrasting current model. Interestingly, 85/422 pneumococcal strains display MICCIP values which were lowered by at least four dilutions by reserpine, pointing at involvement of efflux pumps in FQ-R. In contrast to susceptible strains, isolates resistant to ciprofloxacin significantly overexpressed the ABC pump PatAB in comparison to reference strain S. pneumoniae ATCC 49619, but this could only be linked to disruptive terminator mutations in a fraction of these. Conversely, no difference in expression of the Major Facilitator PmrA, unaffected by reserpine, was noted between susceptible and resistant S. pneumoniae strains. Finally, we observed that four isolates displayed intermediate to high-level ciprofloxacin resistance without any known molecular resistance mechanism. Focusing future molecular studies on these isolates, which are also commonly found in other studies, might greatly assist in the battle against rising pneumococcal drug resistance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / genetics*
  • Amino Acid Substitution
  • Bacterial Proteins / genetics*
  • Belgium / epidemiology
  • DNA Gyrase / genetics*
  • Drug Resistance, Bacterial / drug effects
  • Drug Resistance, Bacterial / genetics*
  • Female
  • Fluoroquinolones / pharmacology*
  • Humans
  • Longitudinal Studies
  • Male
  • Mutation, Missense*
  • Pneumococcal Infections / drug therapy
  • Pneumococcal Infections / epidemiology
  • Pneumococcal Infections / genetics
  • Streptococcus pneumoniae* / genetics
  • Streptococcus pneumoniae* / isolation & purification

Substances

  • ATP-Binding Cassette Transporters
  • Bacterial Proteins
  • Fluoroquinolones
  • DNA Gyrase

Grants and funding

Dr. Vanhoof reports grants and non-financial support from Bayer Healthcare Belgium NV/SA, grants from GlaxoSmith Kline, Belgium, grants from Les Amis des Institutes Pasteur à Bruxelles, non-financial support from Sanofi Aventis, Belgium, during the conduct of the study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.