Characterization of antimicrobial resistance mechanisms in carbapenem-resistant <em>Pseudomonas aeruginosa</em> carrying IMP variants recovered from a Mexican Hospital

Abstract

PurposePseudomonas aeruginosa infections in hospitals constitute an important problem due to the increasing multidrug resistance (MDR) and carbapenems resistance. The knowledge of resistance mechanisms in Pseudomonas strains is an important issue for an adequate antimicrobial treatment. Therefore, the objective was to investigate other antimicrobial resistance mechanisms in MDR P. aeruginosa strains carrying blaIMP, make a partial plasmids characterization, and determine if modifications in oprD gene affect the expression of the OprD protein.MethodologySusceptibility testing was performed by Kirby Baüer and by Minimum Inhibitory Concentration (presence/absence of efflux pump inhibitor); molecular typing by Pulsed-field gel electrophoresis (PFGE), resistance genotyping and integrons by PCR and sequencing; OprD expression by Western blot; plasmid characterization by MOB Typing Technique, molecular size by PFGE-S1; and blaIMP location by Southern blot.ResultsAmong the 59 studied P. aeruginosa isolates, 41 multidrug resistance and carbapenems resistance isolates were detected and classified in 38 different PFGE patterns. Thirteen strains carried blaIMP; 16 blaGES and four carried both genes. This study centered on the 17 strains har-boring blaIMP. New variants of β-lactamases were identified (blaGES-32, blaIMP-56, blaIMP-62) inside of new arrangements of class 1 integrons. The presence of blaIMP gene was detected in two plasmids in the same strain. The participation of the OprD protein and efflux pumps in the resistance to carbapenems and quinolones is shown. No expression of the porin OprD due to stop codon or IS in the gene was found.ConclusionsThis study shows the participation of different resistance mechanisms, which are reflected in the levels of MIC to carbapenems. This is the first report of the presence of three new variants of β-lactamases inside of new arrangements of class 1 integrons, as well as the presence of two plasmids carrying blaIMP in the same P. aeruginosa strain isolated in a Mexican hospital.

High Prevalence of Antimicrobial Resistance Among Gram-Negative Isolated Bacilli in Intensive Care Units at a Tertiary-Care Hospital in Yucatán Mexico

“…Carbapenemases are encoded by genes that are horizontally transferable by plasmids or transposons and commonly associated with genes encoding for other resistance determinants [30]. Carbapenemases, such as IMP- (Imipenem-resistant Pseudomonas), GES- (Guiana extended-spectrum beta-lactamase), VIM- (Veron integron-encoded metallo-beta-lactamase), and OXA-type (oxacillin-hydrolyzing), have been reported in clinical isolates of P. aeruginosa from patients in a hospital in Mexico [31,32]. On the other hand, our Imipenem resistance rates were higher than those reported for the clinical isolates from patients in ICU of a hospital in Saudi Arabia (38.2%) [26].…”

Epidemiology and Diagnostics of Carbapenem Resistance in Gram-negative Bacteria

“…In a Mexican hospital, a significant increase in carbapenem resistance was found between 2011 and 2015, and 96% of carbapenem-resistant K. pneumoniae expressed KPC [69]. In a study by López-García, detection of IMP and GES enzymes was reported in carbapenem-resistant P. aeruginosa ; however, some of the strains had multiple mechanisms present simultaneously, such as MBLs and loss of porin expression, resulting in extremely high meropenem minimum inhibitory concentrations [70]. Among A. baumannii strains, the most common carbapenemase enzymes corresponded to OXA enzymes in this region [27], including OXA-23, OXA-58, OXA-72, OXA-143, and OXA-253; however, NDM-1, VIM-1, IMP-1, and IMP-10 have also been detected.…”

Genomic Context of the Two Integrons of ST-111 Pseudomonas aeruginosa AG1: A VIM-2-carrying Old-acquaintance and a Novel Imp-18-carrying Integron

“…Also, Pae-97 contains a class 1 integron, but with a different arrangement with IMP-1 allele (without OXA nor gcuD genes). Other studies found multiple strains carrying both IMP-18 and OXA-2 (without gcuD nor aacA4) as part of In169 (Sánchez-Martinez et al, 2010) and In1215 (López-García et al, 2018) integrons, including some located in plasmids. Other integrons, such as In96, In614, and In707, have other alleles and arrangements of the same genes (Martínez et al, 2012).…”