Molecular insights into the persistence and co-occurrence of two different carbapenem-resistant Pseudomonas aeruginosa lineages within a hospital setting

ABSTRACT Carbapenem-resistant Pseudomonas aeruginosa (CRPA) represents a critical-priority pathogen capable of causing life-threatening, multidrug-resistant infections. We performed susceptibility testing, whole-genome sequencing, and bioinformatic analyses on 137 CRPA isolates from a Guangdong hospital. We found that the major specimen types were respiratory specimens (57/137, 41.6%) and bronchoalveolar lavage (42/137, 30.7%). All isolates were carbapenem-resistant but had low resistance to polymyxin B (0.7%, 1/137). IncP-6-positive isolates exhibited ≥2- to 32-fold higher resistance to 9/12 antibiotics ( P < 0.05), with no difference to imipenem and meropenem. Fifty-four sequence types and 11 O-serogroups were identified, with ST1971 (6.6%) and O11 (29.9%) being predominant. Temporal and spatial patterns suggest persistent co-occurrence of clade 1 and clade 2 isolates, indicating potential nosocomial outbreak and clonal transmission. IMPORTANCE The prevalence of carbapenem-resistant Pseudomonas aeruginosa (CRPA) has increased rapidly in recent years, yet few genetic and epidemiological studies on CRPA isolates have been performed. We performed susceptibility testing, whole-genome sequencing, and bioinformatic analyses on hospital isolates to investigate their resistance profiles and molecular epidemiology. These findings may offer new insights for developing effective global strategies to control CRPA and reduce untreatable infections in clinical settings.