Great phenotypic and genetic variation among successive chronic Pseudomonas aeruginosa from a cystic fibrosis patient
Authors: Carmen Lozano, José Manuel Azcona-Gutiérrez, Françoise Van Bambeke, Yolanda Sáenz
Journal: PLoS One (2018)
MeSH terms: Cystic Fibrosis / microbiology, Gene Expression Regulation, Bacterial, Genotype, Opportunistic Infections / microbiology, Pseudomonas Infections / microbiology, Pseudomonas aeruginosa / genetics, Case Reports, Research Support, Non-U.S. Gov't, Anti-Bacterial Agents / pharmacology, Bacterial Proteins / genetics, Bacterial Proteins / metabolism, Biofilms / drug effects, Biofilms / growth & development, Chronic Disease, Clone Cells, Cystic Fibrosis / complications, Cystic Fibrosis / drug therapy, Cystic Fibrosis / pathology, Drug Resistance, Bacterial / genetics, Electrophoresis, Gel, Pulsed-Field, Genes, Bacterial, Genetic Variation, Humans, Integrons, Male, Microbial Sensitivity Tests, Middle Aged, Multilocus Sequence Typing, Opportunistic Infections / complications, Opportunistic Infections / drug therapy, Opportunistic Infections / pathology, Porins / genetics, Porins / metabolism, Pseudomonas Infections / complications, Pseudomonas Infections / drug therapy, Pseudomonas Infections / pathology, Pseudomonas aeruginosa / drug effects, Pseudomonas aeruginosa / isolation & purification, Pseudomonas aeruginosa / pathogenicity, Quorum Sensing, Serogroup, beta-Lactamases / genetics, beta-Lactamases / metabolism, Anti-Bacterial Agents, Bacterial Proteins, Porins, OprD protein, Pseudomonas aeruginosa, AmpC beta-lactamases, beta-Lactamases

Background/objectives:
Different adapted Pseudomonas aeruginosa morphotypes are found during chronic infections. Relevant biological determinants in P. aeruginosa successively isolated from a cystic fibrosis (CF) patient were analyzed in this work to gain insight into P. aeruginosa heterogeneity during chronic infection.
Methods:
Seventeen P. aeruginosa isolates collected from a patient over a 3 year period were included, 5 small colony variants (SCV) and 12 mucoids. The following analyses were performed: Pulsed-Field-Gel-Electrophoresis (PFGE)/Multilocus- sequence-typing (MLST)/serotype, antimicrobial susceptibility, growth curves, capacity to form biofilm, pigment production, elastase activity, motility; presence/expression of virulence/quorum sensing genes, and identification of resistance mechanisms.
Results:
All isolates had closely related PFGE patterns and belonged to ST412. Important phenotypic and genotypic differences were found. SCVs were more resistant to antimicrobials than mucoid isolates. AmpC hyperproduction and efflux pump activity were detected. Seven isolates contained two integrons and nine isolates only one integron. All SCVs showed the same OprD profile, while three different profiles were identified among mucoids. No amino acid changes were found in MutL and MutS. All isolates were slow-growing, generally produced high biofilm, had reduced their toxin expression and their quorum sensing, and showed low motility. Nevertheless, statistically significant differences were found among SCV and mucoid isolates. SCVs grew faster, presented higher biofilm formation and flicA expression; but produced less pyorubin and pyocyanin, showed lower elastase activity and rhlR, algD, and lasB expression than mucoid isolates.
Conclusion:
These results help to understand the molecular behavior of chronic P. aeruginosa isolates in CF patients.