Arginine or Nitrate Enhances Antibiotic Susceptibility of
            <i>Pseudomonas aeruginosa</i>
            in Biofilms

Borriello, Giorgia; Richards, L.; Ehrlich, Garth D.; Stewart, Philip S.

doi:10.1128/aac.50.1.382-384.2006

Cited by 105 publications

(83 citation statements)

References 19 publications

(21 reference statements)

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“…One of the major frontline antibiotics used to treat P. aeruginosa biofilm infections is the aminoglycoside tobramycin. The efficacy of tobramycin is either markedly reduced or absent in the absence of oxygen (11,13,37,54), yet a recent study indicates that biofilm P. aeruginosa is more susceptible to tobramycin when cultures are amended with either nitrate or arginine (10). Our study reveals that the entire postglycolytic metabolism of P. aeruginosa is shut down under these conditions.…”

Section: Discussionmentioning

confidence: 70%

Proteomic, Microarray, and Signature-Tagged Mutagenesis Analyses of AnaerobicPseudomonas aeruginosaat pH 6.5, Likely Representing Chronic, Late-Stage Cystic Fibrosis Airway Conditions

et al. 2008

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Patients suffering from cystic fibrosis (CF) commonly harbor the important pathogen Pseudomonas aeruginosa in their airways. During chronic late-stage CF, P. aeruginosa is known to grow under reduced oxygen tension and is even capable of respiring anaerobically within the thickened airway mucus, at a pH of ϳ6.5. Therefore, proteins involved in anaerobic metabolism represent potentially important targets for therapeutic intervention. In this study, the clinically relevant "anaerobiome" or "proteogenome" of P. aeruginosa was assessed. First, two different proteomic approaches were used to identify proteins differentially expressed under anaerobic versus aerobic conditions. Microarray studies were also performed, and in general, the anaerobic transcriptome was in agreement with the proteomic results. However, we found that a major portion of the most upregulated genes in the presence of NO 3 ؊ and NO 2 ؊ are those encoding Pf1 bacteriophage. With anaerobic NO 2 ؊ , the most downregulated genes are those involved postglycolytically and include many tricarboxylic acid cycle genes and those involved in the electron transport chain, especially those encoding the NADH dehydrogenase I complex. Finally, a signature-tagged mutagenesis library of P. aeruginosa was constructed to further screen genes required for both NO 3 ؊ and NO 2 ؊ respiration. In addition to genes anticipated to play important roles in the anaerobiome (anr, dnr, nar, nir, and nuo), the cysG and dksA genes were found to be required for both anaerobic NO 3 ؊ and NO 2 ؊ respiration. This study represents a major step in unraveling the molecular machinery involved in anaerobic NO 3 ؊ and NO 2 ؊ respiration and offers clues as to how we might disrupt such pathways in P. aeruginosa to limit the growth of this important CF pathogen when it is either limited or completely restricted in its oxygen supply.Pseudomonas aeruginosa is a gram-negative bacterium of environmental and clinical importance that is capable of both aerobic and anaerobic respiration, the latter of which requires nitrate (NO 3 Ϫ ), nitrite (NO 2 Ϫ ), or nitrous oxide (N 2 O) as an alternative electron acceptor (24). The organism can also utilize arginine for anaerobic growth via substrate-level phosphorylation, although the final cell yield during this form of growth is abysmally low compared to that observed during anaerobic respiration (55). The most facile means to obtain anaerobic energy, however, is via respiration by NO 3 Ϫ reduction. The process of nitrate reduction can occur by two routes, the first of which is an assimilatory pathway where the nitrogen from NO 3 Ϫ is incorporated into macromolecules via formation of NH 3 . Assimilation can proceed under both aerobic and anaerobic conditions. In contrast, respiratory NO 3 Ϫ reduction (denitrification) occurs only under anaerobic conditions and involves the sequential eight-electron reduction of NO 3 Ϫ to nitrogen gas (N 2 ), with intermediates including NO 2 Ϫ , nitric oxide (NO), and N 2 O. The anaerobic process generates respiratory ...

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Section: Discussionmentioning

confidence: 70%

Proteomic, Microarray, and Signature-Tagged Mutagenesis Analyses of AnaerobicPseudomonas aeruginosaat pH 6.5, Likely Representing Chronic, Late-Stage Cystic Fibrosis Airway Conditions

et al. 2008

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“…Bacteria in biofilms usually exhibit reduced metabolic activity, and by enhancing anaerobic metabolism, NO may favor a transition to a more active state allowing dispersal from the biofilm. Interestingly, recent studies have shown that the addition of nitrate (NO 3 Ϫ ), nitrite (NO 2 Ϫ ), or arginine to P. aeruginosa biofilms resulted in an increase in the sensitivity of the biofilm cells toward antibiotics (10) similar to that observed with NO (5). A NO 3 Ϫ sensor-response regulator system was also found to be involved in biofilm formation and motility in P. aeruginosa (54).…”

Section: Discussionmentioning

confidence: 90%

Nitric Oxide Signaling inPseudomonas aeruginosaBiofilms Mediates Phosphodiesterase Activity, Decreased Cyclic Di-GMP Levels, and Enhanced Dispersal

et al. 2009

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Bacterial biofilms are highly dynamic communities which display a range of differentiated phenotypes during the course of development. By exchange of cell-cell signals, subpopulations of cells can coordinate their activity and undertake particular metabolic tasks or defense strategies (56). At times, the bacterial community releases single cells that escape from the biofilm and revert to a free-swimming, planktonic mode of growth, leaving behind hollow voids in the biofilm architecture (5, 37, 57). This process, referred to as dispersal, completes the biofilm life cycle and is thought to be important for successful colonization of new surfaces. Although the mechanisms underlying these events remain to be fully elucidated, previous studies of various species, including the opportunistic pathogen Pseudomonas aeruginosa, have revealed that dispersal events correlate with the induction of a specific phenotype that involves cellular motility (37, 42).In P. aeruginosa, biofilm dispersal can be triggered by environmental factors, including nutrient (42, 45) and iron (4, 36) availability, and has recently been linked to the intracellular second messenger cyclic di-GMP (c-di-GMP) (45, 47). Numerous studies revealed that decreased c-di-GMP levels are related to a motile mode of growth and to cell dispersal in eubacteria. In this second messenger system, diguanylate cyclases (DGCs) and specific phosphodiesterases (PDEs) are responsible for the biosynthesis and the degradation of c-di-GMP, respectively. DGCs and PDEs contribute to a genetic network that responds to a broad range of environmental cues and/or cell-cell signals and modulate intracellular levels of c-di-GMP, which has been shown to regulate various cellular functions, including biofilm formation, virulence, and dispersal, in many bacterial species (47,(51)(52)(53). Recently, we identified the gas nitric oxide (NO) as an important factor in the regulation of dispersal in P. aeruginosa biofilms (5). Exogenous addition of nontoxic concentrations of NO, typically in the low nanomolar range, was found to stimulate motility and biofilm dispersal in P. aeruginosa. A role for anaerobic metabolism and NO in biofilm dispersal and survival was further supported by other studies of P. aeruginosa (54, 61), Staphylococcus aureus (44), and various single and multispecies biofilms (6).NO is a water-soluble, hydrophobic free radical that can freely diffuse in biological systems. At high concentrations (micromolar to millimolar range), NO

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“…A similar response was observed using the structurally distinct NO donor DEA/NO. The reduced antibacterial response in the presence of the NO scavenger cPTIO, and the lack of response to nitrite and nitrate, indicated that the antimicrobial effects were indeed NO mediated and not associated with the formation of NO 3 Ϫ and NO 2 Ϫ , which have also been shown to increase antibiotic efficacy in P. aeruginosa biofilms (38). The specificity of the NO-mediated response, along with the reduction in the planktonic growth rate observed with Ն500 M SNP, suggests a direct effect on growth and/or regulation of metabolism.…”

Section: Discussionmentioning

confidence: 99%

Low Concentrations of Nitric Oxide Modulate Streptococcus pneumoniae Biofilm Metabolism and Antibiotic Tolerance

Allan

Morgan

Brito-Mutunayagam

et al. 2016

Antimicrob Agents Chemother

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g Streptococcus pneumoniae is one of the key pathogens responsible for otitis media (OM), the most common infection in children and the largest cause of childhood antibiotic prescription. Novel therapeutic strategies that reduce the overall antibiotic consumption due to OM are required because, although widespread pneumococcal conjugate immunization has controlled invasive pneumococcal disease, overall OM incidence has not decreased. Biofilm formation represents an important phenotype contributing to the antibiotic tolerance and persistence of S. pneumoniae in chronic or recurrent OM. We investigated the treatment of pneumococcal biofilms with nitric oxide (NO), an endogenous signaling molecule and therapeutic agent that has been demonstrated to trigger biofilm dispersal in other bacterial species. We hypothesized that addition of low concentrations of NO to pneumococcal biofilms would improve antibiotic efficacy and that higher concentrations exert direct antibacterial effects. Unlike in many other bacterial species, low concentrations of NO did not result in S. pneumoniae biofilm dispersal. Instead, treatment of both in vitro biofilms and ex vivo adenoid tissue samples (a reservoir for S. pneumoniae biofilms) with low concentrations of NO enhanced pneumococcal killing when combined with amoxicillin-clavulanic acid, an antibiotic commonly used to treat chronic OM. Quantitative proteomic analysis using iTRAQ (isobaric tag for relative and absolute quantitation) identified 13 proteins that were differentially expressed following low-concentration NO treatment, 85% of which function in metabolism or translation. Treatment with low-concentration NO, therefore, appears to modulate pneumococcal metabolism and may represent a novel therapeutic approach to reduce antibiotic tolerance in pneumococcal biofilms.

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Arginine or Nitrate Enhances Antibiotic Susceptibility of Pseudomonas aeruginosa in Biofilms

Cited by 105 publications

References 19 publications

Proteomic, Microarray, and Signature-Tagged Mutagenesis Analyses of AnaerobicPseudomonas aeruginosaat pH 6.5, Likely Representing Chronic, Late-Stage Cystic Fibrosis Airway Conditions

Proteomic, Microarray, and Signature-Tagged Mutagenesis Analyses of AnaerobicPseudomonas aeruginosaat pH 6.5, Likely Representing Chronic, Late-Stage Cystic Fibrosis Airway Conditions

Nitric Oxide Signaling inPseudomonas aeruginosaBiofilms Mediates Phosphodiesterase Activity, Decreased Cyclic Di-GMP Levels, and Enhanced Dispersal

Low Concentrations of Nitric Oxide Modulate Streptococcus pneumoniae Biofilm Metabolism and Antibiotic Tolerance

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