New Sequence Type ST3449 in Multidrug-Resistant Pseudomonas aeruginosa Isolates from a Cystic Fibrosis Patient

Abstract

Pseudomonas aeruginosa is one of the most critical bacterial pathogens associated with chronic infections in cystic fibrosis patients. Here we show the phenotypic and genotypic characterization of five consecutive multidrug-resistant isolates of P. aeruginosa collected during a month from a CF patient with end-stage lung disease and fatal outcome. The isolates exhibited distinct colony morphologies and pigmentation and differences in their capacity to produce biofilm and virulence potential evaluated in larvae of Galleria mellonella. Whole genome-sequencing showed that isolates belonged to a novel sequence type ST3449 and serotype O6. Analysis of their resistome demonstrated the presence of genes blaOXA-396, blaPAO, aph(3’)-IIb, catB, crpP and fosA and new mutations in chromosomal genes conferring resistance to different antipseudomonal antibiotics. Genes exoS, exoT, exoY, toxA, lasI, rhlI and tse1 were among the 220 virulence genes detected. The different phenotypic and genotypic features found reveal the adaptation of clone ST3449 to the CF lung environment by a number of mutations affecting genes related with biofilm formation, quorum sensing and antimicrobial resistance. Most of these mutations are commonly found in CF isolates, which may give us important clues for future development of new drug targets to combat P. aeruginosa chronic infections.

Genetic Diversity of Multidrug-Resistant Pseudomonas aeruginosa Isolates Carrying blaVIM–2 and blaKPC–2 Genes That Spread on Different Genetic Environment in Colombia

“…Regarding AmpC polymorphisms, the T105A substitution was detected in most of the isolates, which has been correlated with more efficient carbapenem and cefepime hydrolysis (Cabot et al, 2012). Furthermore, some mutations detected in PmrA and PmrB were observed previously in colistin-sensitive strains (Snesrud et al, 2018); also, some of the alterations in OprD had been described before with no contribution to carbapenem resistance (Horna et al, 2018;Díaz-Ríos et al, 2021).…”

Role of RND Efflux Pumps in Drug Resistance of Cystic Fibrosis Pathogens

“…Non-synonymous mutations have been reported also in the transcriptional regulator of MexAB-OprM, nalC [186]. The same clinical isolates have mutations which lead to the activation of MexT, the positive regulator of MexEF-OprN [186]. A high mutation rate was identified also in the genes encoding the components of RND efflux pumps, such as mexA, mexY, oprM [187] and mexB [188].…”

“…However, another work revealed mutations also in the efflux regulator genes mexR, mexT, and nfxB [185]. Non-synonymous mutations have been reported also in the transcriptional regulator of MexAB-OprM, nalC [186]. The same clinical isolates have mutations which lead to the activation of MexT, the positive regulator of MexEF-OprN [186].…”

Phenotypic and genomic characterization ofPseudomonas aeruginosaisolates recovered from catheter-associated urinary tract infections in an Egyptian hospital

“…In comparison with a previous report (Díaz-Ríos et al, 2021), a total of 220 virulence genes were found among their Pseudomonas biofilm-forming isolates by comparing their WGS and VFDB data. All the isolates were able to produce biofilm.…”