Heterogeneous antimicrobial susceptibility characteristics in Pseudomonas aeruginosa isolates from cystic fibrosis patients

Xuan Qin, Chuan Zhou, Danielle M. Zerr, Amanda Adler, Amin Addetia, Shuhua Yuan, Alexander L. Greninger

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Clinical isolates of Pseudomonas aeruginosa from patients with cystic fibrosis (CF) are known to differ from those associated with non-CF hosts by colony morphology, drug susceptibility patterns, and genomic hypermutability. Pseudomonas aeruginosa isolates from CF patients have long been recognized for their overall reduced rate of antimicrobial susceptibility, but their intraclonal MIC heterogeneity has long been overlooked. Using two distinct cohorts of clinical strains (n = 224 from 56 CF patients, n = 130 from 68 non-CF patients) isolated in 2013, we demonstrated profound Etest MIC heterogeneity in CF P. aeruginosa isolates in comparison to non-CF P. aeruginosa isolates. On the basis of whole-genome sequencing of 19 CF P. aeruginosa isolates from 9 patients with heterogeneous MICs, the core genome phylogenetic tree confirmed the within-patient CF P. aeruginosa clonal lineage along with considerable coding sequence variability. No extrachromosomal DNA elements or previously characterized antibiotic resistance mutations could account for the wide divergence in antimicrobial MICs between P. aeruginosa coisolates, though many heterogeneous mutations in efflux and porin genes and their regulators were present. A unique OprD sequence was conserved among the majority of isolates of CF P. aeruginosa analyzed, suggesting a pseudomonal response to selective pressure that is common to the isolates. Genomic sequence data also suggested that CF pseudomonal hypermutability was not entirely due to mutations in mutL, mutS, and uvr. We conclude that the net effect of hundreds of adaptive mutations, both shared between clonally related isolate pairs and unshared, accounts for their highly heterogeneous MIC variances. We hypothesize that this heterogeneity is indicative of the pseudomonal syntrophic-like lifestyle under conditions of being "locked" inside a host focal airway environment for prolonged periods.

Original languageEnglish (US)
Article numbere00615-17
JournalmSphere
Volume3
Issue number2
DOIs
StatePublished - Mar 1 2018
Externally publishedYes

Keywords

  • Cystic fibrosis
  • Heterogeneous
  • Heteroresistance
  • Isogenic
  • Pseudomonas aeruginosa
  • Syntrophic

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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