Background: Bloodstream and central nervous system infections in children caused by hypervirulent and multidrug-resistant Pseudomonas aeruginosa (PA) are associated with high morbidity and mortality. Methods: PA isolates from 34 blood and CSF samples from children were identified using MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization Time-of-Flight) mass spectrometry and genotyped using MLST. Antibiotic susceptibility testing was performed by the broth microdilution method. Resistance and virulence genes were analyzed by qPCR. Biofilm production was assessed in polystyrene microplates. Results: A total of 34 PA isolates were categorized into 22 MLST genotypes. Among them, 26.5% belonged to ST654 and 9% to ST235. Carbapenem-resistant strains bore bla VIM (72%) and bla GES (20%). Meropenem resistance among isolates was 74%. Resistance to imipenem was exhibited by 76% of isolates with minimum inhibitory concentration ≥16 mg/l. All 34 isolates bore lasB , plcH , and aprA . Other genes were distributed as follows: algD (97%); phzM (94%); nan1 (6%); nan2 (47%); pilA (12%); pilB (41%); exoT (91%); exoU (91%) ; exoS (65%); exoY (32%). The analyzed strains formed strong (47%) and moderate (32%) biofilms. All ST654 and SLV654 isolates had exoT , exoS , exoY , and bla VIM and caused fatal outcomes in four of seven cases. The gene spectrum identified in ST654 and ST235 isolates that caused fatal outcomes differed from that revealed in isolates from recovered patients. Conclusion: The high mortality rate due to PA-associated bacteremia calls for prompt therapy that considers the pathogen's resistance and virulence properties. Further studies are needed to clarify how the combination of PA virulence and resistance factors impacts the progression and severity of infection.
Sadeeva et al. (Fri,) studied this question.