PFGE-Based Evidence of Clonal Relatedness among Pseudomonas aeruginosa ST357 and ST274 Isolates from Cystic Fibrosis Patients at a Brazilian Amazon Referral Center.

Authors

Maria Isabel Montoril Gouveia, Edilene do Socorro Nascimento Falcão Sarges, Emanoele Saraiva Pereira, Jonatan Carlos Cardoso da Silva, Emilly Victória Correia de Miranda, Ana Beatriz Tavares Duarte, Pabllo Antonny Silva Dos Santos, Carolynne Silva Dos Santos, Herald Souza Dos Reis, Danielle Murici Brasiliense, Cintya de Oliveira Souza, Karla Valéria Batista Lima, Yan Corrêa Rodrigues

Published in

Indian journal of medical microbiology. Pages 101247. Aug 14, 2026. Epub Aug 14, 2026.

Abstract

Persistent airway infection by Pseudomonas aeruginosa in cystic fibrosis (CF) is linked to internationally disseminated high-risk clones (HRCs). In a Brazilian Amazon CF cohort, we previously detected recurrent sequence types (STs) ST357 and ST274. Here, we evaluated whether repeated detections represented genetically distinct acquisitions or closely related strains.
We selected ST357 (n=7) and ST274 (n=8) isolates recovered in 2018 from 14 patients (15 isolates total) at a regional CF reference center. Clonality was assessed by PFGE. Disk diffusion (DD) susceptibility testing spanned nine antipseudomonal agents; for agents tested by both methods, results were compared with VITEK-2.
ST357 isolates (7 patients) formed tight subclusters (>88% similarity) including two pairs of indistinguishable strains; overall similarity was 73.6%. ST274 (8 isolates, 7 patients) formed a cohesive cluster (80.2% overall) with one patient showing identical profiles five months apart. All isolates were MDR by DD. β-lactams showed broad non-susceptibility and method comparison revealed substantial discordance for several β-lactams. PFGE identified closely related inter-patient subclusters within ST357 and a cohesive inter-patient ST274 cluster. VITEK-2 yielded frequent susceptible classifications that were discordant with disk-diffusion results, particularly for β-lactams. Clinically consequential discordances should be interpreted cautiously.
Findings support reinforcing CF-specific infection-prevention, implementing periodic genotypic surveillance, and expanding future work to longitudinal/environmental sampling.

PMID:
42600777
Bibliographic data and abstract were imported from PubMed on 15 Aug 2026.

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