• High carbapenem-resistant P. aeruginosa strains carrying blaGES genes. • Five dominant virulence genotypes profiles with key pathogenicity factors like toxA and plcN/H. • Genetic diversity among isolates, indicating no clonal transmission. The aim of this study was to determine the antimicrobial susceptibility, virulence genotypes, presence of extended spectrum β-lactamase (ESBL) and carbapenemase genes, and clonality of Pseudomonas aeruginosa isolates responsible for lower respiratory tract infections in patients admitted to the National Bone Marrow Transplant Center (NBMTC) of Tunisia. During the 11-year study period, a total of 50 P. aeruginosa isolates were responsible for lower respiratory tract infections. Isolates were studied by determining their serotypes, antimicrobial susceptibility, genes encoding ESBL/carbapenemases and virulence factors, and genetic relatedness by ERIC-PCR. High to moderate resistance rates were observed for ticarcillin, ticarcillin–clavulanic acid, piperacillin–tazobactam, ceftazidime, cefepime, imipenem, meropenem, ciprofloxacin, amikacin, and fosfomycin. One isolate showed an ESBL phenotype encoded by the bla SHV-2a gene. Of 13 isolates resistant to both imipenem and meropenem, the bla GES gene was amplified in nine isolates. Isolates exhibited 19 virulence genotypes, of which five were prevalent: V1 (14 genes; n = 14), V2 (14 genes, n = 6), V3 (all genes, n = 6), V4 (13 genes, n = 5), and V5 (13 genes, n = 5). ERIC-PCR showed high genetic heterogeneity. These findings highlight the high genetic heterogeneity of P. aeruginosa isolates in these neutropenic patients, as well as their remarkable pathogenic power, raising significant concern. El objetivo de este estudio fue evaluar un conjunto de aislados de Pseudomonas aeruginosa responsables de infecciones de las vías respiratorias bajas en pacientes ingresados en el Centro Nacional de Trasplante de Médula Ósea (CNTMO) de Túnez, focalizando en la sensibilidad a los antimicrobianos, los genotipos de virulencia, la presencia de genes de β-lactamasa de espectro extendido (BLEE) y carbapenemasa y la clonalidad. Durante un período de estudio de 11 años, se recuperaron 50 aislados de P. aeruginosa a partir de infecciones respiratorias bajas. Se determinaron los serotipos y el parentesco genético se estableció mediante la técnica ERIC-PCR. Se observaron tasas de resistencia de moderadas a altas frente a ticarcilina, ticarcilina-ácido clavulánico, piperacilina-tazobactam, ceftazidima, cefepima, imipenem, meropenem, ciprofloxacina, amikacina y fosfomicina. Solo un aislado presentó el fenotipo BLEE codificado por el gen bla SHV-2a . Entre las 13 cepas resistentes a imipenem y meropenem, 9 dieron positiva la amplificación del gen bla GES . Los aislados exhibieron 19 genotipos de virulencia, de los cuales 5 fueron predominantes: V1 (14 genes; n = 14), V2 (14 genes; n = 6), V3 (todos los genes; n = 6), V4 (13 genes; n = 5) y V5 (13 genes; n = 5). La ERIC-PCR reveló una elevada heterogeneidad genética. Estos hallazgos evidencian la gran heterogeneidad genética de los aislados de P. aeruginosa en estos pacientes neutropénicos, así como su alto potencial patógeno, lo que constituye un importante motivo de preocupación clínica.
Raddaoui et al. (Mon,) studied this question.
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