<p>Molecular Epidemiology and Mechanisms of High-Level Resistance to Meropenem and Imipenem in <em>Pseudomonas aeruginosa</em></p>

Abstract

Purpose: Pseudomonas aeruginosa possesses a large number of resistance mechanisms to different antimicrobials with carbapenems being the most powerful in treating resistant P. aeruginosa. Hence, it is imperative to explore different mechanisms of carbapenemsresistance in P. aeruginosa to achieve successful treatment through the design of new drugs acting on this interaction to combat against antimicrobial resistance. Strains and Methods: A total of 634 P. aeruginosa clinical isolates were collected from various patient sources and their MIC levels were measured. Molecular evaluation of carbapenem resistance was assessed by investigating the presence of bla IMP1 , bla IMP2 , bla VIM1 , bla VIM2 , bla SPM and bla NDM genes and the gene expression of the following multidrug efflux pump systems: MexAB-OprM, MexCD-OprJ, MexEF-OprN and MexXY-OprM and its correlation with MIC. Isolates were typed by Random Amplified Polymorphic DNA (RAPD)-typing. Results: Carbapenem resistance was detected in 32 (5%) isolates, which were all imipenem resistant (of which 29 were meropenem resistant). High-level resistance (≥64mg/mL) to imipenem was found in 27 (84.3%) isolates, and to meropenem in 28 (96.5%) isolates. The carbapenemase bla VIM-1 was found in 31 isolates, while bla NDM was detected in 4 isolates. None of the isolates possessed either bla-VIM-2 , bla IMP-1 , bla IMP-2 or bla SPM. The majority of the isolates displayed over-expression of MexCD-OprJ (75%) followed by MexXY-OprM efflux pump (62%), while MexAB-OprM and MexEF-OprN efflux pumps were overexpressed in 21.8% and 18.7% of the isolates, respectively, with no down-regulation of oprD in any of the isolates. A strong correlation was found between CDJ efflux pump expression and meropenem, imipenem resistance (r=0.532, 0.654, p<0.001, <0.001) respectively. Four major clusters were detected by RAPD-typing: group 1(10 isolates), group 3 (9 isolates), group 2 (8 isolates) while the fourth group (4) included 4 isolates (12.5% polymorphism). Conclusion: High-level carbapenem resistance reported in this study was allied to multiple mechanisms including carbapenemase production and efflux-pump over-expression. Threatening cross-infection is possible inside the hospital and stringent infection control measures are crucial.

It’s Not Easy Being Green: A Narrative Review on the Microbiology, Virulence and Therapeutic Prospects of Multidrug-Resistant Pseudomonas aeruginosa

“…The permeability of the P. aeruginosa outer membrane is restricted (10-150× lower than that of E. coli), leading to the intrinsic non-susceptibility to many previously listed agents (coupled with their efflux). In addition, any changes to the constituents of this cell wall structure will unavoidably affect the susceptibilities of antibiotics [177,178]. P. aeruginosa porins (β-barrel proteins folding within the outer membrane composed of anti-parallel β-sheets) are classified into non-specific (OprF), specific (OprB, OprD or the D2 porin, OprE, OprO, OprP), gated (OprC, OprH), and efflux (OprM, OprN, OprJ) porins [179].…”

“…Among different porins of P. aeruginosa, OprF is the most common non-lipoprotein within the outer membrane (the E. coli homolog porin is OmpA), which is involved in securing the integrity of the outer membrane, QS, biofilm formation, bacterial adhesion, and acute and chronic infections [179,180]. β-lactam antibiotics and fluoroquinolones enter bacterial cells through the abovementioned porin channels, aminoglycosides are taken up by a two-step process, involving the presence of oxygen-or nitrogen-dependent electron transport chains, while colistin facilitates its own uptake by interacting with the Gram-negative LPS [176][177][178][179][180]. The absence of oxygen (e.g., in the depths of a biofilm or in anaerobic bacteria) or the functional deficiency of ATPases may lead to resistance against aminoglycosides [181].…”

“…On the other hand, the importance of the OprD porin mutations in the presence of carbapenem resistance has been demonstrated by several studies. In fact, porin alterations are one of the most common resistance mechanisms after repeated exposure to carbapenems [176][177][178][179][180][181][182][183][184][185][186][187][188][189]. The cited literature reports highlight the importance of the continuous surveillance of bacterial pathogens possessing β-lactamases (including phenotypic and molecular methods) to aid antimicrobial stewardship interventions and to help in utilizing the safest and most appropriate therapeutic alternatives available [248].…”

<p>Antimicrobial Resistance and Genotyping of Bacteria Isolated from Urinary Tract Infection in Children in an Iranian Referral Hospital</p>

“…Mamishi et al The RAPD-PCR is a simple, rapid, easy, inexpensive, and reproducible method that has been widely used in bacterial epidemiology and finding of bacterial genetic similarity that is crucial for cross-infection assessment. 15,25,28,31 Cross-sectional transmission, especially from the urology unit to other wards, may lead to strains transmission causing nosocomial infection through the hospital. Therefore, much attention should be paid to the basic methods of preventing infection (standard precautions).…”

Insights on carbapenem-resistant Pseudomonas aeruginosa

“…Nevertheless, in >60% of cases, β-lactam antibiotics are used in the therapy of P. aeruginosa infections, therefore resistance against these agents (especially carbapenems) is a significant clinical concern (Algammal et al 2020;Bassetti et al 2018;Behzadi et al 2021). The emergence of carbapenem-resistant P. aeruginosa (CRPA) may occur through a combination of resistance mechanisms, including decreased membrane permeability and porin loss (e.g., OprD, OprF porin mutants), overexpression of efflux pumps (MexAB-OprM and MexCD-OprJ), changes in penicillin-binding proteins (PBPs) and the production of either chromosomally-encoded or plasmid-mediated β-lactamase enzymes (carbapenemases) capable of hydrolyzing these drugs (Hassuna et al 2020;Mirzaei et al 2020). While in some non-fermenters possess chromosomally-mediated β-lactamases are the norm (e.g., L1 and L2 metallo-β-lactamases in Stenotrophomonas malthophilia), carbapenemases encoded on mobile genetic present a serious public health issue, as they are capable of widespread dissemination (Gajdács and Urbán 2019;Poole 2011); additionally, these genetic elements often include a wide range of other resistance determinants.…”