scholarly journals Role of the MexEF-OprN Efflux System in Low-Level Resistance of Pseudomonas aeruginosa to Ciprofloxacin

2011 ◽  
Vol 55 (12) ◽  
pp. 5676-5684 ◽  
Author(s):  
Catherine Llanes ◽  
Thilo Köhler ◽  
Isabelle Patry ◽  
Barbara Dehecq ◽  
Christian van Delden ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Reference Strain ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Efflux System ◽  
Content Type ◽  
Clinical Strains ◽  
Major Mechanism ◽  
Level Resistance

ABSTRACTIn this study, we investigated the resistance mechanisms to fluoroquinolones of 85 non-cystic fibrosis strains ofPseudomonas aeruginosaexhibiting a reduced susceptibility to ciprofloxacin (MICs from 0.25 to 2 μg/ml). In addition to MexAB-OprM (31 of 85 isolates) and MexXY/OprM (39 of 85), the MexEF-OprN efflux pump (10 of 85) was found to be commonly upregulated in this population that is considered susceptible or of intermediate susceptibility to ciprofloxacin, according to current breakpoints. Analysis of the 10 MexEF-OprN overproducers (nfxCmutants) revealed the presence of various mutations in themexT(2 isolates),mexS(5 isolates), and/ormvaT(2 isolates) genes, the inactivation of which is known to increase the expression of themexEF-oprNoperon in reference strain PAO1-UW. However, these genes were intact in 3 of 10 of the clinical strains. Interestingly, ciprofloxacin at 2 μg/ml or 4 μg/ml preferentially selectednfxCmutants from wild-type clinical strains (n= 10 isolates) and from first-step mutants (n= 10) overexpressing Mex pumps, thus indicating that MexEF-OprN represents a major mechanism by whichP. aeruginosamay acquire higher resistance levels to fluoroquinolones. These data support the notion that thenfxCmutants may be more prevalent in the clinical setting than anticipated and strongly suggest the involvement of still unknown genes in the regulation of this efflux system.

scholarly journals Identification of Novel Efflux Proteins Rv0191, Rv3756c, Rv3008, and Rv1667c Involved in Pyrazinamide Resistance in Mycobacterium tuberculosis

2017 ◽  
Vol 61 (8) ◽  
Author(s):  
Yumeng Zhang ◽  
Jia Zhang ◽  
Peng Cui ◽  
Ying Zhang ◽  
Wenhong Zhang
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Efflux Pump ◽  
Binding Studies ◽  
Content Type ◽  
Clinical Strains ◽  
Efflux Pump Inhibitors ◽  
Level Resistance ◽  
Pyrazinoic Acid ◽  
Increased Susceptibility ◽  
Efflux Proteins

ABSTRACT Pyrazinamide (PZA) is a critical drug used for the treatment of tuberculosis (TB). PZA is a prodrug that requires conversion to the active component pyrazinoic acid (POA) by pyrazinamidase (PZase) encoded by the pncA gene. Although resistance to PZA is mostly caused by pncA mutations and less commonly by rpsA, panD, and clpC1 mutations, clinical strains without these mutations are known to exist. While efflux of POA was demonstrated in Mycobacterium tuberculosis previously, the efflux proteins involved have not been identified. Here we performed POA binding studies with an M. tuberculosis proteome microarray and identified four efflux proteins (Rv0191, Rv3756c, Rv3008, and Rv1667c) that bind POA. Overexpression of the four efflux pump genes in M. tuberculosis caused low-level resistance to PZA and POA but not to other drugs. Furthermore, addition of efflux pump inhibitors such as reserpine, piperine, and verapamil caused increased susceptibility to PZA in M. tuberculosis strains overexpressing the efflux proteins Rv0191, Rv3756c, Rv3008, and Rv1667c. Our studies indicate that these four efflux proteins may be responsible for PZA/POA efflux and cause PZA resistance in M. tuberculosis. Future studies are needed to assess their roles in PZA resistance in clinical strains.

scholarly journals PA3225 Is a Transcriptional Repressor of Antibiotic Resistance Mechanisms in Pseudomonas aeruginosa

2017 ◽  
Vol 61 (8) ◽  
Author(s):  
Clayton W. Hall ◽  
Li Zhang ◽  
Thien-Fah Mah
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Efflux Pump ◽  
Regulatory Region ◽  
Resistance Mechanisms ◽  
Wild Type ◽  
Type Vi Secretion System ◽  
Planktonic Cells ◽  
Content Type ◽  
Dependent Protein

ABSTRACT The tssABC1 locus is part of the Hcp secretion island I (HSI-I) type VI secretion system (T6SS) in Pseudomonas aeruginosa. Previous work implicated the tssC1 gene in P. aeruginosa biofilm-specific antibiotic resistance, and tssC1 is preferentially expressed in biofilms compared to planktonic cells. Using a DNA-dependent protein pulldown approach, we discovered that PA3225, an uncharacterized LysR-type transcriptional regulator, specifically bound to the tssABC1 upstream regulatory region. The deletion of PA3225 led to a 2-fold decrease in tssA1 expression levels in planktonic cells compared to the wild type, and tssA1 expression was slightly reduced in ΔPA3225 biofilms compared to wild-type biofilms. Intriguingly, further investigations revealed that the ΔPA3225 mutant was less susceptible to multiple, structurally unrelated antibiotics with various mechanisms of action when grown planktonically. The ΔPA3225 mutant was additionally more resistant to ciprofloxacin when grown in a biofilm. The decreased antibiotic susceptibility of the ΔPA3225 strain was linked to the transcriptional upregulation of the MexAB-OprM efflux pump. By using transcriptome sequencing (RNA-seq), other PA3225-regulated genes were identified, and the products of these genes, such as the putative ABC transporter PA3228, may also contribute to antibiotic resistance.

scholarly journals Mutations in Ribosomal Protein RplA or Treatment with Ribosomal Acting Antibiotics Activates Production of Aminoglycoside Efflux Pump SmeYZ in Stenotrophomonas maltophilia

2019 ◽  
Vol 64 (2) ◽  
Author(s):  
Karina Calvopiña ◽  
Punyawee Dulyayangkul ◽  
Matthew B. Avison
Keyword(s):  
Ribosomal Protein ◽  
Stenotrophomonas Maltophilia ◽  
Efflux Pump ◽  
Clinical Isolates ◽  
Efflux System ◽  
Aminoglycoside Resistance ◽  
Content Type ◽  
Ribosomal Protein L1 ◽  
Significant Mechanism

ABSTRACT Aminoglycoside resistance in Stenotrophomonas maltophilia is multifactorial, but the most significant mechanism is overproduction of the SmeYZ efflux system. By studying laboratory-selected mutants and clinical isolates, we show here that damage to the 50S ribosomal protein L1 (RplA) activates SmeYZ production. We also show that gentamicin and minocycline, which target the ribosome, induce expression of smeYZ. These findings explain the role of SmeYZ in both intrinsic and mutationally acquired aminoglycoside resistance.

scholarly journals Resistance and Virulence of Pseudomonas aeruginosa Clinical Strains Overproducing the MexCD-OprJ Efflux Pump

2008 ◽  
Vol 52 (7) ◽  
pp. 2455-2462 ◽  
Author(s):  
Katy Jeannot ◽  
Sylvie Elsen ◽  
Thilo Köhler ◽  
Ina Attree ◽  
Christian van Delden ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Term Therapy ◽  
Clinical Strains ◽  
Initial Description ◽  
Moderate Resistance ◽  
Long Term Therapy ◽  
Variable Impact ◽  
Level Resistance

ABSTRACT Since their initial description 2 decades ago, MexCD-OprJ-overproducing efflux mutants of Pseudomonas aeruginosa (also called nfxB mutants) have rarely been described in the clinical setting. Screening of 110 nonreplicate clinical isolates showing moderate resistance to ciprofloxacin (MIC from 0.5 μg/ml to 4 μg/ml) yielded only four mutants (3.6%) of that type harboring various alterations in the repressor gene nfxB. MexCD-OprJ upregulation correlated with an increased resistance to ciprofloxacin, cefepime, and chloramphenicol in most of the clinical strains, concomitant with a higher susceptibility to ticarcillin, aztreonam, imipenem, and aminoglycosides. Evidence was obtained that this increased susceptibility to aminoglycosides results from the impaired activity of efflux pump MexXY-OprM. Furthermore, MexCD-OprJ upregulation was found to impair bacterial growth and to have a strain-specific, variable impact on rhamnolipid, elastase, phospholipase C, and pyocyanin production. Review of patient files indicated that the four nfxB mutants were responsible for confirmed cases of infection and emerged during long-term therapy with ciprofloxacin. Taken together, these data show that, while rather infrequent among P. aeruginosa strains with low-level resistance to ciprofloxacin, MexCD-OprJ-overproducing mutants may be isolated after single therapy with fluoroquinolones and may be pathogenic.

scholarly journals Novel ERG11 and TAC1b Mutations Associated with Azole Resistance in Candida auris

2021 ◽  
Vol 65 (5) ◽  
Author(s):  
Jizhou Li ◽  
Alix T. Coste ◽  
Maroussia Liechti ◽  
Daniel Bachmann ◽  
Dominique Sanglard ◽  
...  
Keyword(s):  
Invasive Candidiasis ◽  
Efflux Pump ◽  
Cumulative Effect ◽  
Resistance Mechanisms ◽  
Azole Resistance ◽  
Candida Auris ◽  
Content Type ◽  
Drug Classes ◽  
In The Wild

ABSTRACT Candida auris is a novel Candida species that has spread in all continents, causing nosocomial outbreaks of invasive candidiasis. C. auris has the ability to develop resistance to all antifungal drug classes. Notably, many C. auris isolates are resistant to the azole drug fluconazole, a standard therapy for invasive candidiasis. Azole resistance in C. auris can result from mutations in the azole target gene ERG11 and/or overexpression of the efflux pump Cdr1. TAC1 is a transcription factor controlling CDR1 expression in C. albicans. The role of TAC1 homologs in C. auris (TAC1a and TAC1b) remains to be better defined. In this study, we compared sequences of ERG11, TAC1a, and TAC1b between a fluconazole-susceptible and five fluconazole-resistant C. auris isolates of clade IV. Among four of the resistant isolates, we identified similar genotypes with concomitant mutations in ERG11 (F444L) and TAC1b (S611P). The simultaneous deletion of tandemly arranged TAC1a/TAC1b resulted in a decrease of MIC for fluconazole. Introduction of the ERG11 and TAC1b mutations separately and/or combined in the wild-type azole-susceptible isolate resulted in a significant increase of azole resistance with a cumulative effect of the two combined mutations. Interestingly, CDR1 expression was not significantly affected by TAC1a/TAC1b deletion or by the presence of the TAC1b S611P mutation, suggesting the existence of Tac1-dependent and Cdr1-independent azole resistance mechanisms. In conclusion, we demonstrated the role of two previously unreported mutations responsible for azole resistance in C. auris, which were a common signature among four azole-resistant isolates of clade IV.

scholarly journals Constitutive Activation of MexT by Amino Acid Substitutions Results in MexEF-OprN Overproduction in Clinical Isolates ofPseudomonas aeruginosa

2018 ◽  
Vol 62 (5) ◽  
Author(s):  
Paulo Juarez ◽  
Isabelle Broutin ◽  
Christophe Bordi ◽  
Patrick Plésiat ◽  
Catherine Llanes
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Regulatory Gene ◽  
Clinical Isolates ◽  
Amino Acid Substitutions ◽  
Multidrug Efflux ◽  
Efflux System ◽  
Content Type ◽  
Constitutive Activation ◽  
Multidrug Efflux System

ABSTRACTWhen overproduced, the multidrug efflux system MexEF-OprN increases the resistance ofPseudomonas aeruginosato fluoroquinolones, chloramphenicol, and trimethoprim. In this work, we demonstrate that gain-of-function mutations in the regulatory genemexTresult in oligomerization of the LysR regulator MexT, constitutive upregulation of the efflux pump, and increased resistance in clinical isolates.

scholarly journals Role of the MexAB-OprM Efflux Pump of Pseudomonas aeruginosa in Tolerance to Tea Tree (Melaleuca alternifolia) Oil and Its Monoterpene Components Terpinen-4-ol, 1,8-Cineole, and α-Terpineol

2008 ◽  
Vol 74 (6) ◽  
pp. 1932-1935 ◽  
Author(s):  
Chelsea J. Papadopoulos ◽  
Christine F. Carson ◽  
Barbara J. Chang ◽  
Thomas V. Riley
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Agent ◽  
Efflux Pump ◽  
Multidrug Efflux ◽  
Efflux System ◽  
Melaleuca Alternifolia ◽  
Tea Tree ◽  
Multidrug Efflux System

ABSTRACT Using a series of efflux mutants of Pseudomonas aeruginosa, the MexAB-OprM pump was identified as contributing to this organism's tolerance to the antimicrobial agent tea tree (Melaleuca alternifolia) oil and its monoterpene components terpinen-4-ol, 1,8-cineole, and α-terpineol. These data show that a multidrug efflux system of P. aeruginosa can extrude monoterpenes and related alcohols.

scholarly journals Carbapenem Resistance Mechanisms in Pseudomonas aeruginosa Clinical Isolates

2001 ◽  
Vol 45 (2) ◽  
pp. 480-484 ◽  
Author(s):  
Hyunjoo Pai ◽  
Jong-Won Kim ◽  
Jungmin Kim ◽  
Ji Hyang Lee ◽  
Kang Won Choe ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Amino Acid Substitution ◽  
Carbapenem Resistance ◽  
Resistance Mechanisms ◽  
Clinical Isolates ◽  
Efflux System ◽  
Clinical Strains ◽  
Carbapenem Resistant

ABSTRACT In order to define the contributions of the mechanisms for carbapenem resistance in clinical strains of Pseudomonas aeruginosa, we investigated the presence of OprD, the expressions of the MexAB-OprM and MexEF-OprN systems, and the production of the β-lactamases for 44 clinical strains. All of the carbapenem-resistant isolates showed the loss of or decreased levels of OprD. Three strains overexpressed the MexAB-OprM efflux system by carrying mutations inmexR. These three strains had the amino acid substitution in MexR protein, Arg (CGG) → Gln (CAG), at the position of amino acid 70. None of the isolates, however, expressed the MexEF-OprN efflux system. For the characterization of β-lactamases, at least 13 isolates were the depressed mutants, and 12 strains produced secondary β-lactamases. Based on the above resistance mechanisms, the MICs of carbapenem for the isolates were analyzed. The MICs of carbapenem were mostly determined by the expression of OprD. The MICs of meropenem were two- to four-fold increased for the isolates which overexpressed MexAB-OprM in the background of OprD loss. However, the elevated MICs of meropenem for some individual isolates could not be explained. These findings suggested that other resistance mechanisms would play a role in meropenem resistance in clinical isolates of P. aeruginosa.

scholarly journals Activity of Ceftolozane-Tazobactam against Carbapenem-Resistant, Non-Carbapenemase-Producing Pseudomonas aeruginosa and Associated Resistance Mechanisms

2017 ◽  
Vol 62 (1) ◽  
Author(s):  
Yu Mi Wi ◽  
Kerryl E. Greenwood-Quaintance ◽  
Audrey N. Schuetz ◽  
Kwan Soo Ko ◽  
Kyong Ran Peck ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Resistance Mechanisms ◽  
Resistance Rate ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Carbapenem Resistant ◽  
Kill Curve ◽  
Time Kill

ABSTRACT Although carbapenems are effective for treating serious multidrug-resistant Pseudomonas aeruginosa infections, carbapenem-resistant P. aeruginosa (CRPA) is now being reported worldwide. Ceftolozane-tazobactam (C/T) demonstrates activity against many multidrug-resistant isolates. We evaluated the activity of C/T and compared its activity to that of ceftazidime-avibactam (C/A) using a well-characterized collection of non-carbapenemase-producing CRPA isolates. Forty-two non-carbapenemase-producing CRPA isolates from a previous study (J. Y. Lee and K. S. Ko, Int J Antimicrob Agents 40:168–172, 2012, https://doi.org/10.1016/j.ijantimicag.2012.04.004) were included. All had been previously shown to be negative for bla IMP, bla VIM, bla SPM, bla GIM, bla SIM, and bla KPC by PCR. In the prior study, expression of oprD, ampC, and several efflux pump genes had been defined by quantitative reverse transcription-PCR. Here, antimicrobial susceptibility was determined by broth microdilution according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Time-kill curve assays were performed using three C/T- and C/A-susceptible CRPA isolates. Among 42 non-carbapenemase-producing CRPA isolates, overall susceptibility to C/T was 95.2%, compared to 71.4%, 42.9%, 23.8%, 21.4%, and 2.4% for C/A, ceftazidime, piperacillin-tazobactam, cefepime, and meropenem, respectively. The C/T resistance rate was significantly lower than that of C/A among isolates showing decreased oprD and increased mexB expression (5.1% versus 25.6%, P = 0.025, and 4.3% versus 34.8%, P = 0.022, respectively). In time-kill curve studies, C/T was less bactericidal than C/A against an isolate with decreased oprD and increased ampC expression. C/T was active against 95.2% of non-carbapenemase-producing CRPA clinical isolates. No apparent correlation of C/T MIC values with specific mutation-driven resistance mechanisms was noted.

scholarly journals Differential selection of multidrug efflux systems by quinolones in Pseudomonas aeruginosa.

1997 ◽  
Vol 41 (11) ◽  
pp. 2540-2543 ◽  
Author(s):  
T Köhler ◽  
M Michea-Hamzehpour ◽  
P Plesiat ◽  
A L Kahr ◽  
J C Pechere
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Fluorine Atom ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Multidrug Efflux ◽  
Efflux System ◽  
In Vitro Exposure ◽  
Structural Determinant ◽  
Selection Of

Resistance mechanisms selected after in vitro exposure to 12 quinolones were analyzed for Pseudomonas aeruginosa. Efflux-type mutants were predominant. Quinolones differed in their ability to select a particular efflux system. While the newer fluoroquinolones favored the MexCD-OprJ system, the older quinolones selected exclusively the MexEF-OprN or MexAB-OprM systems. A protonable C-7 substituent in combination with a C-6 fluorine atom is a structural determinant of quinolones involved in efflux pump substrate specificity.

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