Journal Article

Genomic heterogeneity underlies multidrug resistance in Pseudomonas aeruginosa: A population-level analysis beyond susceptibility testing

Konstan, Michael W., Vila, Alejandro J., Martinez, Octavio, Cardenas, Monica, Colin, Andrew A., Bonomo, Robert A., Benjamino, Jacquelynn, Scott, Jacob G., Rhoads, Daniel D., Pérez-Cardona, Armando, Mack, Andrew R., LiPuma, John J., Rojas, Laura J., Abbo, Lilian M., DeRonde, Kailynn J., Perez, Federico, Krishnan, Nikhil P., Adams, Mark D., Marshall, Steven M., Yasmin, Mohamad, Smania, Andrea, Jacobs, Michael R.

2022

Overview

Pseudomonas aeruginosa is a persistent and difficult-to-treat pathogen in many patients, especially those with Cystic Fibrosis (CF). Herein, we describe a longitudinal analysis of a series of multidrug resistant (MDR) P. aeruginosa isolates recovered in a 17-month period, from a young female CF patient who underwent double lung transplantation. Our goal was to understand the genetic basis of the observed resistance phenotypes, establish the genomic population diversity, and define the nature of sequence evolution over time. Twenty-two sequential P. aeruginosa isolates were obtained within a 17-month period, before and after a double-lung transplant. At the end of the study period, antimicrobial susceptibility testing, whole genome sequencing (WGS), phylogenetic analyses and RNAseq were performed in order to understand the genetic basis of the observed resistance phenotypes, establish the genomic population diversity, and define the nature of sequence changes over time. The majority of isolates were resistant to almost all tested antibiotics. A phylogenetic reconstruction revealed 3 major clades representing a genotypically and phenotypically heterogeneous population. The pattern of mutation accumulation and variation of gene expression suggested that a group of closely related strains was present in the patient prior to transplantation and continued to change throughout the course of treatment. A trend toward accumulation of mutations over time was observed. Different mutations in the DNA mismatch repair gene mutL consistent with a hypermutator phenotype were observed in two clades. RNAseq performed on 12 representative isolates revealed substantial differences in the expression of genes associated with antibiotic resistance and virulence traits. The overwhelming current practice in the clinical laboratories setting relies on obtaining a pure culture and reporting the antibiogram from a few isolated colonies to inform therapy decisions. Our analyses revealed significant underlying genomic heterogeneity and unpredictable evolutionary patterns that were independent of prior antibiotic treatment, highlighting the need for comprehensive sampling and population-level analysis when gathering microbiological data in the context of CF P. aeruginosa chronic infection. Our findings challenge the applicability of antimicrobial stewardship programs based on single-isolate resistance profiles for the selection of antibiotic regimens in chronic infections such as CF.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Accumulation / Adaptation / Analysis / Anti-Bacterial Agents - pharmacology / Anti-Bacterial Agents - therapeutic use / Antibiotic resistance / Antibiotics / Antiinfectives and antibacterials / Antimicrobial agents / Bioinformatics / Biology and Life Sciences / Chronic infection / Cystic fibrosis / Cystic Fibrosis - complications / Cystic Fibrosis - drug therapy / Cystic Fibrosis - genetics / Decision analysis / Deoxyribonucleic acid / DNA / DNA repair / DNA sequencing / Drug resistance / Drug Resistance, Multiple / Epidemiology / Female / Gene expression / Gene sequencing / Genetic aspects / Genomics / Hematology / Heterogeneity / Hospitals / Humans / Infections / Infectious diseases / Laboratories / Lung transplantation / Lungs / Medicine / Medicine and Health Sciences / Microbial Sensitivity Tests / Mismatch repair / Molecular biology / Multidrug resistance / Multidrug resistant organisms / Mutation / Nucleotide sequencing / Oncology / Pathogens / Pathology / Patients / Pediatrics / Phenotypes / Phylogeny / Population / Proteomics / Pseudomonas aeruginosa / Pseudomonas Infections - microbiology / Pure culture / Radiation / Research and analysis methods / Stokes, Louis / Transplantation / Veterans / Virulence / Whole genome sequencing