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 Antagonistic Interactions of Pseudomonas aeruginosa Antibiotic Resistance Mechanisms in Planktonic but Not Biofilm Growth

2011 ◽  
Vol 55 (10) ◽  
pp. 4560-4568 ◽  
Author(s):  
Xavier Mulet ◽  
Bartolomé Moyá ◽  
Carlos Juan ◽  
María D. Macià ◽  
José L. Pérez ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Efflux Pump ◽  
Resistance Mechanisms ◽  
Negative Regulator ◽  
Intrinsic Resistance ◽  
Major Drawback ◽  
Biofilm Growth ◽  
Content Type ◽  
Bacterial Physiology

ABSTRACTPseudomonas aeruginosahas an extraordinary capacity to evade the activity of antibiotics through a complex interplay of intrinsic and mutation-driven resistance pathways, which are, unfortunately, often additive or synergistic, leading to multidrug (or even pandrug) resistance. However, we show that one of these mechanisms, overexpression of the MexCD-OprJ efflux pump (driven by inactivation of its negative regulator NfxB), causes major changes in the cell envelope physiology, impairing the backbone ofP. aeruginosaintrinsic resistance, including the major constitutive (MexAB-OprM) and inducible (MexXY-OprM) efflux pumps and the inducible AmpC β-lactamase. Moreover, it also impaired the most relevant mutation-driven β-lactam resistance mechanism (constitutive AmpC overexpression), through a dramatic decrease in periplasmic β-lactamase activity, apparently produced by an abnormal permeation of AmpC out of the cell. While these results could delineate future strategies for combating antibiotic resistance in cases of acute nosocomial infections, a major drawback for the potential exploitation of the described antagonistic interaction between resistance mechanisms came from the differential bacterial physiology characteristics of biofilm growth, a hallmark of chronic infections. Although the failure to concentrate AmpC activity in the periplasm dramatically limits the protection of the targets (penicillin-binding proteins [PBPs]) of β-lactams at the individual cell level, the expected outcome for cells growing as biofilm communities, which are surrounded by a thick extracellular matrix, was less obvious. Indeed, our results showed that AmpC produced bynfxBmutants is protective in biofilm growth, suggesting that the permeation of AmpC into the matrix protects biofilm communities against β-lactams.

scholarly journals Effect of Nitroxides on Swarming Motility and Biofilm Formation, Multicellular Behaviors in Pseudomonas aeruginosa

2013 ◽  
Vol 57 (10) ◽  
pp. 4877-4881 ◽  
Author(s):  
César de la Fuente-Núñez ◽  
Fany Reffuveille ◽  
Kathryn E. Fairfull-Smith ◽  
Robert E. W. Hancock
Keyword(s):  
Nitric Oxide ◽  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Wild Type ◽  
Planktonic Cells ◽  
Swarming Motility ◽  
Content Type ◽  
Exogenous Addition ◽  
Biofilm Dispersion ◽  
Dispersal Activity

ABSTRACTThe ability of nitric oxide (NO) to induce biofilm dispersion has been well established. Here, we investigated the effect of nitroxides (sterically hindered nitric oxide analogues) on biofilm formation and swarming motility inPseudomonas aeruginosa. A transposon mutant unable to produce nitric oxide endogenously (nirS) was deficient in swarming motility relative to the wild type and the complemented strain. Moreover, expression of thenirSgene was upregulated by 9.65-fold in wild-type swarming cells compared to planktonic cells. Wild-type swarming levels were substantially restored upon the exogenous addition of nitroxide containing compounds, a finding consistent with the hypothesis that NO is necessary for swarming motility. Here, we showed that nitroxides not only mimicked the dispersal activity of NO but also prevented biofilms from forming in flow cell chambers. In addition, anirStransposon mutant was deficient in biofilm formation relative to the wild type and the complemented strain, thus implicating NO in the formation of biofilms. Intriguingly, despite its stand-alone action in inhibiting biofilm formation and promoting dispersal, a nitroxide partially restored the ability of anirSmutant to form biofilms.

scholarly journals Differing Effects of Combination Chemotherapy with Meropenem and Tobramycin on Cell Kill and Suppression of Resistance of Wild-Type Pseudomonas aeruginosa PAO1 and Its Isogenic MexAB Efflux Pump-Overexpressed Mutant

2009 ◽  
Vol 53 (6) ◽  
pp. 2266-2273 ◽  
Author(s):  
G. L. Drusano ◽  
Weiguo Liu ◽  
Christine Fregeau ◽  
Robert Kulawy ◽  
Arnold Louie
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Drug Interaction ◽  
Combination Chemotherapy ◽  
Drug Exposure ◽  
Inhibitory Concentration ◽  
Efflux Pump ◽  
Area Under The Curve ◽  
Resistance Mechanisms ◽  
Wild Type ◽  
Resistant Mutants

ABSTRACT The drug interaction terminology (synergy, additivity, antagonism) relates to bacterial kill. The suppression of resistance requires greater drug exposure. We examined the combination of meropenem and tobramycin for kill and resistance suppression (wild-type Pseudomonas aeruginosa PAO1 and its isogenic MexAB-overexpressed mutant). The drug interaction was additive. The introduction of MexAB overexpression significantly altered the 50% inhibitory concentration of meropenem but not that of tobramycin, resulting in the recovery of a marked increase in colony numbers from drug-containing plates. For the wild type, more tobramycin-resistant isolates than meropenem-resistant isolates were present, and the tobramycin-resistant isolates were harder to suppress. MexAB overexpression unexpectedly caused a significant increase in the number of tobramycin-resistant mutants, as indexed to the area under the curve of slices through the inverted U resistance mountain. The differences were significant, except in the absence of meropenem. We hypothesize that the pump resulted in the presence of less meropenem for organism inhibition, allowing more rounds of replication and also affecting the numbers of tobramycin-resistant mutants. When resistance suppression is explored by combination chemotherapy, it is important to examine the impacts of differing resistance mechanisms for both agents.

scholarly journals Multidrug Adaptive Resistance of Pseudomonas aeruginosa Swarming Cells

2019 ◽  
Vol 64 (3) ◽  
Author(s):  
Shannon R. Coleman ◽  
Travis Blimkie ◽  
Reza Falsafi ◽  
Robert E. W. Hancock
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Efflux Pump ◽  
Iron Acquisition ◽  
Polymyxin B ◽  
Rna Seq ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Content Type ◽  
Adaptive Resistance

ABSTRACT Swarming surface motility is a complex adaptation leading to multidrug antibiotic resistance and virulence factor production in Pseudomonas aeruginosa. Here, we expanded previous studies to demonstrate that under swarming conditions, P. aeruginosa PA14 is more resistant to multiple antibiotics, including aminoglycosides, β-lactams, chloramphenicol, ciprofloxacin, tetracycline, trimethoprim, and macrolides, than swimming cells, but is not more resistant to polymyxin B. We investigated the mechanism(s) of swarming-mediated antibiotic resistance by examining the transcriptomes of swarming cells and swarming cells treated with tobramycin by transcriptomics (RNA-Seq) and reverse transcriptase quantitative PCR (qRT-PCR). RNA-Seq of swarming cells (versus swimming) revealed 1,581 dysregulated genes, including 104 transcriptional regulators, two-component systems, and sigma factors, numerous upregulated virulence and iron acquisition factors, and downregulated ribosomal genes. Strain PA14 mutants in resistome genes that were dysregulated under swarming conditions were tested for their ability to swarm in the presence of tobramycin. In total, 41 mutants in genes dysregulated under swarming conditions were shown to be more resistant to tobramycin under swarming conditions, indicating that swarming-mediated tobramycin resistance was multideterminant. Focusing on two genes downregulated under swarming conditions, both prtN and wbpW mutants were more resistant to tobramycin, while the prtN mutant was additionally resistant to trimethoprim under swarming conditions; complementation of these mutants restored susceptibility. RNA-Seq of swarming cells treated with subinhibitory concentrations of tobramycin revealed the upregulation of the multidrug efflux pump MexXY and downregulation of virulence factors.

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 Expression ofPseudomonas aeruginosaAntibiotic Resistance Genes Varies Greatly during Infections in Cystic Fibrosis Patients

2018 ◽  
Vol 62 (11) ◽  
Author(s):  
Lois W. Martin ◽  
Cynthia L. Robson ◽  
Annabelle M. Watts ◽  
Andrew R. Gray ◽  
Claire E. Wainwright ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cystic Fibrosis ◽  
Antibiotic Resistance ◽  
Efflux Pump ◽  
Antibiotic Resistance Gene ◽  
Resistance Mechanisms ◽  
Laboratory Culture ◽  
Bacterial Cells ◽  
Content Type ◽  
Key Factor

ABSTRACTThe lungs of individuals with cystic fibrosis (CF) become chronically infected withPseudomonas aeruginosathat is difficult to eradicate by antibiotic treatment. Two keyP. aeruginosaantibiotic resistance mechanisms are the AmpC β-lactamase that degrades β-lactam antibiotics and MexXYOprM, a three-protein efflux pump that expels aminoglycoside antibiotics from the bacterial cells. Levels of antibiotic resistance gene expression are likely to be a key factor in antibiotic resistance but have not been determined during infection. The aims of this research were to investigate the expression of theampCandmexXgenes during infection in patients with CF and in bacteria isolated from the same patients and grown under laboratory conditions.P. aeruginosaisolates from 36 CF patients were grown in laboratory culture and gene expression measured by reverse transcription-quantitative PCR (RT-qPCR). The expression ofampCvaried over 20,000-fold and that ofmexXover 2,000-fold between isolates. The median expression levels of both genes were increased by the presence of subinhibitory concentrations of antibiotics. To measureP. aeruginosagene expression during infection, we carried out RT-qPCR using RNA extracted from fresh sputum samples obtained from 31 patients. The expression ofampCvaried over 4,000-fold, whilemexXexpression varied over 100-fold, between patients. Despite these wide variations, median levels of expression ofampCin bacteria in sputum were similar to those in laboratory-grown bacteria. The expression ofmexXwas higher in sputum than in laboratory-grown bacteria. Overall, our data demonstrate that genes that contribute to antibiotic resistance can be highly expressed in patients, but there is extensive isolate-to-isolate and patient-to-patient variation.

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 Overexpression of MexCD-OprJ Reduces Pseudomonas aeruginosa Virulence by Increasing Its Susceptibility to Complement-Mediated Killing

2014 ◽  
Vol 58 (4) ◽  
pp. 2426-2429 ◽  
Author(s):  
Inmaculada Martínez-Ramos ◽  
Xavier Mulet ◽  
Bartolomé Moyá ◽  
Mariette Barbier ◽  
Antonio Oliver ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Immune System ◽  
Antimicrobial Resistance ◽  
Type Strain ◽  
Wild Type Strain ◽  
Host Immune System ◽  
Wild Type ◽  
Content Type ◽  
Increased Susceptibility

ABSTRACTWe evaluated the resistance to complement-mediated killing of a collection of isogenicPseudomonas aeruginosastrains expressing different antimicrobial resistance phenotypes. Only thenfxBmutant demonstrated increased susceptibility to complement compared with that for the wild-type strain. This increment was due to the overexpression of MexCD-OprJ, which led to increased C3 opsonization and a reduced ability to infect the lungs of mice. Our results show that the acquisition of antibiotic resistance may alter the interplay ofP. aeruginosawith the host immune system.

scholarly journals Efflux Pumps in Chromobacterium Species Increase Antibiotic Resistance and Promote Survival in a Coculture Competition Model

2019 ◽  
Vol 85 (19) ◽  
Author(s):  
Saida Benomar ◽  
Kara C. Evans ◽  
Robert L. Unckless ◽  
Josephine R. Chandler
Keyword(s):  
Antibiotic Resistance ◽  
Efflux Pump ◽  
Gene Clusters ◽  
Efflux Pumps ◽  
Resistance Mechanisms ◽  
Competition Model ◽  
Content Type ◽  
Resistance Induction ◽  
Resistance Nodulation Division

ABSTRACT Members of the Chromobacterium genus include opportunistic but often-fatal pathogens and soil saprophytes with highly versatile metabolic capabilities. In previous studies of Chromobacterium subtsugae (formerly C. violaceum) strain CV017, we identified a resistance nodulation division (RND)-family efflux pump (CdeAB-OprM) that confers resistance to several antibiotics, including the bactobolin antibiotic produced by the soil saprophyte Burkholderia thailandensis. Here, we show the cdeAB-oprM genes increase C. subtsugae survival in a laboratory competition model with B. thailandensis. We also demonstrate that adding sublethal bactobolin concentrations to the coculture increases C. subtsugae survival, but this effect is not through CdeAB-OprM. Instead, the increased survival requires a second, previously unreported pump we call CseAB-OprN. We show that in cells exposed to sublethal bactobolin concentrations, the cseAB-oprN genes are transcriptionally induced, and this corresponds to an increase in bactobolin resistance. Induction of this pump is highly specific and sensitive to bactobolin, while CdeAB-OprM appears to have a broader range of antibiotic recognition. We examine the distribution of cseAB-oprN and cdeAB-oprM gene clusters in members of the Chromobacterium genus and find the cseAB-oprN genes are limited to the nonpathogenic C. subtsugae strains, whereas the cdeAB-oprM genes are more widely distributed among members of the Chromobacterium genus. Our results provide new information on the antibiotic resistance mechanisms of Chromobacterium species and highlight the importance of efflux pumps for saprophytic bacteria existing in multispecies communities. IMPORTANCE Antibiotic efflux pumps are best known for increasing antibiotic resistance of pathogens; however, the role of these pumps in saprophytes is much less well defined. This study describes two predicted efflux pump gene clusters in the Chromobacterium genus, which is comprised of both nonpathogenic saprophytes and species that cause highly fatal human infections. One of the predicted efflux pump clusters is present in every member of the Chromobacterium genus and increases resistance to a broad range of antibiotics. The other gene cluster has more narrow antibiotic specificity and is found only in Chromobacterium subtsugae, a subset of entirely nonpathogenic species. We demonstrate the role of both pumps in increasing antibiotic resistance and demonstrate the importance of efflux-dependent resistance induction for C. subtsugae survival in a dual-species competition model. These results have implications for managing antibiotic-resistant Chromobacterium infections and for understanding the evolution of efflux pumps outside the host.

scholarly journals Lack of the Major Multifunctional Catalase KatA in Pseudomonas aeruginosa Accelerates Evolution of Antibiotic Resistance in Ciprofloxacin-Treated Biofilms

2019 ◽  
Vol 63 (10) ◽  
Author(s):  
Marwa N. Ahmed ◽  
Andreas Porse ◽  
Ahmed Abdelsamad ◽  
Morten Sommer ◽  
Niels Høiby ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Defense Mechanism ◽  
Efflux Pump ◽  
Negative Regulator ◽  
Content Type ◽  
Iron Assimilation ◽  
In The Wild

ABSTRACT During chronic biofilm infections, Pseudomonas aeruginosa bacteria are exposed to increased oxidative stress as a result of the inflammatory response. As reactive oxygen species (ROS) are mutagenic, the evolution of resistance to ciprofloxacin (CIP) in biofilms under oxidative stress conditions was investigated. We experimentally evolved six replicate populations of P. aeruginosa lacking the major catalase KatA in colony biofilms and stationary-phase cultures for seven passages in the presence of subinhibitory levels (0.1 mg/liter) of CIP or without CIP (eight replicate lineages for controls) under aerobic conditions. In CIP-evolved biofilms, a larger CIP-resistant subpopulation was isolated in the ΔkatA strain than in the wild-type (WT) PAO1 population, suggesting oxidative stress as a promoter of the development of antibiotic resistance. A higher number of mutations identified by population sequencing were observed in evolved ΔkatA biofilm populations (CIP and control) than in WT PAO1 populations evolved under the same conditions. Genes involved in iron assimilation were found to be exclusively mutated in CIP-evolved ΔkatA biofilm populations, probably as a defense mechanism against ROS formation resulting from Fenton reactions. Furthermore, a hypermutable lineage due to mutL inactivation developed in one CIP-evolved ΔkatA biofilm lineage. In CIP-evolved biofilms of both the ΔkatA strain and WT PAO1, mutations in nfxB, the negative regulator of the MexCD-OprJ efflux pump, were observed while in CIP-evolved planktonic cultures of both the ΔkatA strain and WT PAO1, mutations in mexR and nalD, regulators of the MexAB-OprM efflux pump, were repeatedly found. In conclusion, these results emphasize the role of oxidative stress as an environmental factor that might increase the development of antibiotic resistance in in vivo biofilms.

Sign in / Sign up

Export Citation Format

Share Document