Molecular characterization of multidrug-resistant (MDR) Pseudomonas aeruginosa isolated in a burn center

- Two new P. aeruginosa STs displaying carbapenems resistance.
- STs with different pathogenic potential: biofilm production and exoU presence.
- β-Lactamase production was not the major cause of carbapenems resistance.
- Biofilm production in Clone A may explain its persistence in this unit.

ObjectiveThe aim of this study was to characterize molecularly multidrug-resistant (MDR) Pseudomonas aeruginosa isolates collected from burn center (BC) patients and environment in a hospital localized in Rio de Janeiro city, RJ, Brazil.MethodsThirty-five P. aeruginosa isolates were studied. The antimicrobial resistance was tested by disk diffusion method as recommended by CLSI. The assessment of virulence (exoS and exoU) and resistance (blaPER-1, blaCTX-M, blaOXA-10, blaGES-1, blaVIM, blaIMP, blaSPM-1, blaKPC, blaNDM and blaSIM) genes were achieved through PCR and biofilm forming capacity was determined using a microtiter plates based-assay, as described previously. Genotyping was performed using Multilocus sequence typing (MLST).ResultsHigh rate of P. aeruginosa (71.4%; 25/35) were classified as MDR, of them 64% (16/25) were related to clone A, the most prevalent clone found in the BC studied. A total of eight carbapenems resistant isolates were detected; three belonging to clone A and five carrying the exoU virulence gene. In addition, clone A isolates were also biofilm producers. Two new sequence types (ST) were detected in this study: ST2236, grouped in to clone A; and ST2237, classified in the different clones, displaying carbapenem resistance and exoU virulence gene.ConclusionThe high prevalence of biofilm producers and multiresistant P. aeruginosa isolates in BC indicates that prevention programs need to be implemented to avoid infection in highly susceptible patients.