Incidence and Characterization of Carbapenem Resistance Mediated by Acquired Beta-Lactamases in Pseudomonas aeruginosa Isolates from a Bulgarian Cancer Hospital

Detection of clinical isolates of Pseudomonas aeruginosa producing metallo-????-lactamases (MBL) and extended-spectrum ????-lactamases (ESBL) is essential to adequately treat patients and control the spread of resistance. We investigated the frequency of carbapenem resistance mediated by acquired ????-lactamases in P. aeruginosa isolates from a tertiary cancer hospital in Bulgaria. The prevalence of P. aeruginosa infec¬tions was relatively low - approximately 2% of all hospital-acquired infections, while the carbapenem re¬sistance rate was estimated at 25% in 2023. Carbapenem resistance due to VIM and NDM MBL types was observed in 8/54 (14.81%) isolates. PER, VEB, or GES ESBLs were detected in a total of 8/54 (14.81%) isolates including 3 isolates co-harbouring NDM and GES enzymes. The overall frequency of 24.07% (13/54) of acquired carbapenemase and ESBL genes in our study reflects the multicomponent nature of carbapenem resistance in P. aeruginosa and highlights the need for reliable screening.