Characterization of carbapenem resistance mechanisms and integrons in Pseudomonas aeruginosa strains from blood samples in a French hospital

Abstract

Metallo-b-lactamases (MBLs), porin OprD, integrons, virulence factors and the clonal relationships were characterized in imipenem-resistant Pseudomonas aeruginosa (IRPA) isolates. Fifty-six IRPA strains were recovered from blood samples of different patients at a Toulouse teaching hospital from 2011 to 2013. Susceptibility testing of 14 antibiotics was performed by the disc diffusion method. Detection and characterization of MBLs, the oprD gene and integrons were studied by PCR and sequencing. Thirteen genes involved in the virulence of P. aeruginosa were analysed. Molecular typing of IRPA strains was performed by PFGE and multilocus sequence typing. In this study, 61 % of the IRPA isolates showed a multi-resistance phenotype. The MBL phenotype, detected in three isolates (5.4 %), was linked to the bla VIM-2 gene. The oprD gene was amplified in 55 (98.2 %) IRPA strains, and variations were observed in 54 of them. Insertion sequences (IS) truncating oprD were detected in eight IRPA strains, with the novel ISPa56 identified in two strains. Class 1 integrons were detected in 24 (42.9 %) IRPA strains. The bla VIM-2 gene was found inside the class 1 integron arrangements. The new integrons In1054 (intI1-aacA56-qacED1-sul1) and In1160 (intI1-aacA4-aacC1d-ISKpn4-gcuE-qacED1-sul1) have been described for the first time, to the best of our knowledge, in this study. A high clonal diversity was found in our strains. Among the variety of sequence types (STs) found, ST175, ST233, ST235, ST244 and ST654 were noteworthy as epidemic clones. In conclusion, 5.4 % of IRPA strains showed an MBL phenotype linked to the bla VIM-2 gene. The identified oprD high polymorphism could be implicated in the variable resistance to carbapenems in IRPA strains. The dissemination of high-risk clones is a cause of concern.

High incidence of MBL-mediated imipenem resistance among Pseudomonas aeruginosa from surgical site infections in Egypt

“…Various mechanisms could be responsible for carbapenems resistance in P. aeruginosa including the decrease in the permeability of the cell-wall, intrinsic efflux systems over-expression in addition to production of hydrolyzing enzymes particularly MBLs. The presence of MBLs is responsible for about 40% of IRPA isolates all over the world; 39% in a surveillance program in Italy [29] and 40% in Portugal [30], with higher rates reported in Pakistan (764.9%) [31] and remarkably lower rates in France (5.6%) [32].…”

Study of Resistance Pattern in Mucoid and Non Mucoid Isolates of Pseudomonas aeruginosa from Lower Respiratory Tract Specimens in a Tertiary Care Centre of Western U.P.

“…18,19 Resistance to the carbapenems in P. aeruginosa is often caused by impermeability through alteration or loss of the porin OprD, increased expression of an efflux pump, or the production of class B metallo-β-lactamases (MBLs). 20,21,22 MBL producing P. aeruginosa have emerged as one of the most feared resistance mechanisms. MBL production in P. aeruginosa can be detected by molecular methods and phenotypic methods.…”

Genotypes and metallo-beta-lactamases carriage in carbapenem-resistant Pseudomonas aeruginosa isolated from children in Moscow

“…Этот сиквенстип относится к числу международных клонов, хотя его распространенность ограничена по сравне нию с ST111 и ST235 [8]. ST654 появился в цирку ляции не позднее 2006 г. и описан в Великобритании [9], Польше [10], Франции [11], Аргентине [12] и Син гапуре, для которого данный генотип эндемичен [13]. Единичные изоляты ST654 были импортированы в Швецию (как предполагается, из Туниса) [14] и Канаду (изолят от пациента, находившегося на длительном ле чении в Индии) [15].…”