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Kobayashi H, Isozaki M, Fukuda T, Anzai Y, Kato F. Surveillance of Fluoroquinolone-Resistant Clinical Isolates of <i>Pseudomonas aeruginosa</i>. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/ojmm.2013.32022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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352
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Cicek AC, Saral A, Duzgun AO, Cizmeci Z, Kayman T, Balci PO, Dal T, Firat M, Yazici Y, Sancaktar M, Ozgumus OB, Sandalli C. Screening of Class 1 and Class 2 Integrons in Clinical Isolates of Pseudomonas aeruginosa Collected from Seven Hospitals in Turkey: A Multicenter Study. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/ojmm.2013.34034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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353
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Koch DC, Raunest M, Harder T, Kandt C. Unilateral access regulation: ground state dynamics of the Pseudomonas aeruginosa outer membrane efflux duct OprM. Biochemistry 2012; 52:178-87. [PMID: 23234291 DOI: 10.1021/bi3014714] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Acting as an efflux duct in the MexA-MexB-OprM multidrug efflux pump, OprM plays a major role in the antibiotic resistance capability of Pseudomonas aeruginosa, trafficking substrates through the outer cell membrane. Whereas the available crystal structures showed restricted OprM access on both ends, the underlying gating mechanism is not yet fully understood. To gain insight into the functional mechanism of OprM access regulation, we conducted a series of five independent, unbiased molecular dynamics simulations, computing 200 ns dynamics samples of the wild-type protein in a phospholipid membrane/150 mM NaCl water environment. On the extracellular side, OprM opens and closes freely under the simulated conditions, suggesting the absence of a gating mechanism on this side of the isolated protein. On the periplasmic side, we observe an opening of the tip regions at Val408 and to a lesser degree Asp416 located 1.5 nm further into the channel, leading to OprM end conformations being up to 3 and 1.4 times, respectively, more open than the asymmetric crystal structure. If our simulations are correct, our findings imply that periplasmic gating involves only the Asp416 region and that in vivo additional components, absent in our simulation, might be required for periplasmic gating if the observed opening trend near Asp416 is not negligible. In addition to that ,we identified in each monomer a previously unreported sodium binding site in the channel interior coordinated by Asp171 and Asp230 whose functional role remains to be investigated.
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Affiliation(s)
- Dennis C Koch
- Computational Structural Biology, Department of Life Science Informatics B-IT, Life & Medical Sciences (LIMES) Institute, University of Bonn, Dahlmannstrasse 2, 53113 Bonn, Germany
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354
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Tracking down antibiotic-resistant Pseudomonas aeruginosa isolates in a wastewater network. PLoS One 2012; 7:e49300. [PMID: 23284623 PMCID: PMC3526604 DOI: 10.1371/journal.pone.0049300] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 10/08/2012] [Indexed: 11/19/2022] Open
Abstract
The Pseudomonas aeruginosa-containing wastewater released by hospitals is treated by wastewater treatment plants (WWTPs), generating sludge, which is used as a fertilizer, and effluent, which is discharged into rivers. We evaluated the risk of dissemination of antibiotic-resistant P. aeruginosa (AR-PA) from the hospital to the environment via the wastewater network. Over a 10-week period, we sampled weekly 11 points (hospital and urban wastewater, untreated and treated water, sludge) of the wastewater network and the river upstream and downstream of the WWTP of a city in eastern France. We quantified the P. aeruginosa load by colony counting. We determined the susceptibility to 16 antibiotics of 225 isolates, which we sorted into three categories (wild-type, antibiotic-resistant and multidrug-resistant). Extended-spectrum β-lactamases (ESBLs) and metallo-β-lactamases (MBLs) were identified by gene sequencing. All non-wild-type isolates (n = 56) and a similar number of wild-type isolates (n = 54) were genotyped by pulsed-field gel electrophoresis and multilocus sequence typing. Almost all the samples (105/110, 95.5%) contained P. aeruginosa, with high loads in hospital wastewater and sludge (≥3×106 CFU/l or/kg). Most of the multidrug-resistant isolates belonged to ST235, CC111 and ST395. They were found in hospital wastewater and some produced ESBLs such as PER-1 and MBLs such as IMP-29. The WWTP greatly reduced P. aeruginosa counts in effluent, but the P. aeruginosa load in the river was nonetheless higher downstream than upstream from the WWTP. We conclude that the antibiotic-resistant P. aeruginosa released by hospitals is found in the water downstream from the WWTP and in sludge, constituting a potential risk of environmental contamination.
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355
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Evaluation of an expanded microarray for detecting antibiotic resistance genes in a broad range of gram-negative bacterial pathogens. Antimicrob Agents Chemother 2012; 57:458-65. [PMID: 23129055 DOI: 10.1128/aac.01223-12] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A microarray capable of detecting genes for resistance to 75 clinically relevant antibiotics encompassing 19 different antimicrobial classes was tested on 132 Gram-negative bacteria. Microarray-positive results correlated >91% with antimicrobial resistance phenotypes, assessed using British Society for Antimicrobial Chemotherapy clinical breakpoints; the overall test specificity was >83%. Microarray-positive results without a corresponding resistance phenotype matched 94% with PCR results, indicating accurate detection of genes present in the respective bacteria by microarray when expression was low or absent and, hence, undetectable by susceptibility testing. The low sensitivity and negative predictive values of the microarray results for identifying resistance to some antimicrobial resistance classes are likely due to the limited number of resistance genes present on the current microarray for those antimicrobial agents or to mutation-based resistance mechanisms. With regular updates, this microarray can be used for clinical diagnostics to help accurate therapeutic options to be taken following infection with multiple-antibiotic-resistant Gram-negative bacteria and prevent treatment failure.
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356
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Guan R, Ho MC, Fröhlich RFG, Tyler PC, Almo SC, Schramm VL. Methylthioadenosine deaminase in an alternative quorum sensing pathway in Pseudomonas aeruginosa. Biochemistry 2012; 51:9094-103. [PMID: 23050701 DOI: 10.1021/bi301062y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pseudomonas aeruginosa possesses an unusual pathway for 5'-methylthioadenosine (MTA) metabolism involving deamination to 5'-methylthioinosine (MTI) followed by N-ribosyl phosphorolysis to hypoxanthine and 5-methylthio-α-d-ribose 1-phosphate. The specific MTI phosphorylase of P. aeruginosa has been reported [Guan, R., Ho, M. C., Almo, S. C., and Schramm, V. L. (2011) Biochemistry 50, 1247-1254], and here we characterize MTA deaminase from P. aeruginosa (PaMTADA). Genomic analysis indicated the PA3170 locus to be a candidate for MTA deaminase (MTADA). Protein encoded by PA3170 was expressed and shown to deaminate MTA with 40-fold greater catalytic efficiency for MTA than for adenosine. The k(cat)/K(m) value of 1.6 × 10(7) M(-1) s(-1) for MTA is the highest catalytic efficiency known for an MTA deaminase. 5'-Methylthiocoformycin (MTCF) is a 4.8 pM transition state analogue for PaMTADA but causes no significant inhibition of human adenosine deaminase or MTA phosphorylase. MTCF is permeable to P. aeruginosa and exhibits an IC(50) of 3 nM on cellular PaMTADA activity. PaMTADA is the only activity in P. aeruginosa extracts to act on MTA. MTA and 5-methylthio-α-d-ribose are involved in quorum sensing pathways; thus, PaMTADA is a potential target for quorum sensing. The crystal structure of PaMTADA in complex with MTCF shows the transition state mimic 8(R)-hydroxyl group in contact with a catalytic site Zn(2+), the 5'-methylthio group in a hydrophobic pocket, and the transition state mimic of the diazepine ring in contact with a catalytic site Glu.
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Affiliation(s)
- Rong Guan
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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357
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Wang L, Zhang C, Gong F, Li H, Xie X, Xia C, Chen J, Song Y, Shen A, Song J. Influence of Pseudomonas aeruginosa pvdQ gene on altering antibiotic susceptibility under swarming conditions. Curr Microbiol 2012; 66:152-61. [PMID: 23090643 DOI: 10.1007/s00284-012-0217-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 06/24/2011] [Indexed: 11/24/2022]
Abstract
In Pseudomonas aeruginosa PAO1, the pvdQ gene has been shown to have at least two functions. It encodes the acylase enzyme and hydrolyzes 3-oxo-C12-HSL, the key signaling molecule of quorum sensing system. In addition, pvdQ is involved in swarming motility. It is required and up-regulated during swarming motility, which is triggered by high cell densities. As high density bacterial populations also display elevated antibiotics resistance, studies have demonstrated swarm-cell differentiation in P. aeruginosa promotes increased resistance to various antibiotics. PvdQ acts as a signal during swarm-cell differentiation, and thus may play a role in P. aeruginosa antibiotic resistance. The aim of this study was to examine whether pvdQ was involved in modifying antibiotic susceptibility during swarming conditions and to investigate the mechanism by which this occurred. We constructed the PAO1pMEpvdQ strain, which overproduces PvdQ. PAO1pMEpvdQ promotes swarming motility, while PAO1ΔpvdQ abolishes swarming motility. In addition, both PAO1 and PAO1pMEpvdQ acquired resistance to ceftazidime, ciprofloxacin, meropenem, polymyxin B, and gentamicin, though PAO1pMEpvdQ exhibited a twofold to eightfold increase in antibiotic resistance compared to PAO1. These results indicate that pvdQ plays an important role in elevating antibiotic resistance via swarm-cell differentiation and possibly other mechanisms as well. We analyzed outer membrane permeability. Our data also suggest that pvdQ decreases P. aeruginosa outer membrane permeability, thereby elevating antibiotic resistance under swarming conditions. Our results suggest new approaches for reducing P. aeruginosa resistance.
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Affiliation(s)
- Lili Wang
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, Hubei Province, China.
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358
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Roberts AEL, Maddocks SE, Cooper RA. Manuka honey is bactericidal against Pseudomonas aeruginosa and results in differential expression of oprF and algD. MICROBIOLOGY-SGM 2012; 158:3005-3013. [PMID: 23082035 DOI: 10.1099/mic.0.062794-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The presence of Pseudomonas aeruginosa in cutaneous wounds is of clinical significance and can lead to persistent infections. Manuka honey has gained ground in clinical settings due to its effective therapeutic action and broad spectrum of antibacterial activity. In this study, the effect of manuka honey on P. aeruginosa was investigated using MIC, MBC, growth kinetics, confocal microscopy, atomic force microscopy and real-time PCR. A bactericidal mode of action for manuka honey against P. aeruginosa was deduced (12 %, w/v, MIC; 16 %, w/v, MBC) and confirmed by confocal and atomic force microscopy, which showed extensive cell lysis after 60 min exposure to inhibitory concentrations of manuka honey. The inability of honey-treated cells to form microcolonies was demonstrated and investigated using Q-PCR for three key microcolony-forming genes: algD, lasR and oprF. The expression of algD increased 16-fold whereas oprF expression decreased 10-fold following honey treatment; lasR expression remained unaltered. These findings confirm that manuka honey is effective at inducing cell lysis and identify two targets, at the genetic level, that might be involved in this process.
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Affiliation(s)
- Aled E L Roberts
- Cardiff Metropolitan University, Western Avenue, Cardiff CF5 2YB, UK
| | - Sarah E Maddocks
- Cardiff Metropolitan University, Western Avenue, Cardiff CF5 2YB, UK
| | - Rose A Cooper
- Cardiff Metropolitan University, Western Avenue, Cardiff CF5 2YB, UK
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359
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Gbaguidi-Haore H, Dumartin C, L'Heriteau F, Pefau M, Hocquet D, Rogues AM, Bertrand X. Antibiotics involved in the occurrence of antibiotic-resistant bacteria: a nationwide multilevel study suggests differences within antibiotic classes. J Antimicrob Chemother 2012; 68:461-70. [DOI: 10.1093/jac/dks406] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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360
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Antibiotic resistance amongst healthcare-associated pathogens in China. Int J Antimicrob Agents 2012; 40:389-97. [PMID: 22999767 PMCID: PMC7135469 DOI: 10.1016/j.ijantimicag.2012.07.009] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 07/03/2012] [Accepted: 07/12/2012] [Indexed: 11/23/2022]
Abstract
The People's Republic of China, commonly known as China, comprises approximately one-fifth of the world's population. Because of the expanding size and density of its population and the frequent interaction of people with animals, China is a hotspot for the emergence and spread of new microbial threats and is a major contributor to the worldwide infectious disease burden. In recent years, the emergence and rapid spread of severe acute respiratory syndrome (SARS) generated considerable interest in the Chinese healthcare system and its infection control and prevention measures. This review examines antibiotic misuse and the status of antibiotic resistance in the Chinese healthcare system. China has high rates of antibiotic resistance driven by misuse of these agents in a healthcare system that provides strong incentives for overprescribing and in a country where self-medication is common. Tuberculosis remains a serious problem in China, with a high prevalence of multidrug-resistant and extensively drug-resistant strains. Drug resistance amongst nosocomial bacteria has been on a rapid upward trend with a strong inclination towards multidrug resistance. There is a need for effective infection prevention and control measures and strict use of antibiotics in China to control the rise and spread of antibiotic resistance in the country.
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361
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Khuntayaporn P, Montakantikul P, Mootsikapun P, Thamlikitkul V, Chomnawang MT. Prevalence and genotypic relatedness of carbapenem resistance among multidrug-resistant P. aeruginosa in tertiary hospitals across Thailand. Ann Clin Microbiol Antimicrob 2012; 11:25. [PMID: 22970983 PMCID: PMC3475077 DOI: 10.1186/1476-0711-11-25] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 09/09/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Increased infection caused by multidrug resistant (MDR) Pseudomonas aeruginosa has raised awareness of the resistance situation worldwide. Carbapenem resistance among MDR (CR-MDR) P. aeruginosa has become a serious life-threatening problem due to the limited therapeutic options. Therefore, the objectives of this study were to determine the prevalence, the antibiotic susceptibility patterns and the relatedness of CR-MDR P. aeruginosa in tertiary hospitals across Thailand. METHODS MDR P. aeruginosa from eight tertiary hospitals across Thailand were collected from 2007-2009. Susceptibility of P. aeruginosa clinical isolates was determined according to the Clinical and Laboratory Standards Institute guideline. Selected CR-MDR P. aeruginosa isolates were genetically analyzed by pulsed-field gel electrophoresis. RESULTS About 261 clinical isolates were identified as MDR P. aeruginosa and approximately 71.65% were found to be CR-MDR P. aeruginosa. The result showed that the meropenem resistance rate was the highest reaching over 50% in every hospitals. Additionally, the type of hospitals was a major factor affecting the resistance rate, as demonstrated by significantly higher CR-MDR rates among university and regional hospitals. The fingerprinting map identified 107 clones with at least 95% similarity. Only 4 clones were detected in more than one hospital. CONCLUSIONS Although the antibiotic resistance rate was high, the spreading of CR-MDR was found locally. Specific strains of CR-MDR did not commonly spread from one hospital to another. Importantly, clonal dissemination ratio indicated limited intra-hospital transmission in Thailand.
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Affiliation(s)
- Piyatip Khuntayaporn
- Department of Microbiology, Faculty of Pharmacy, Mahidol University, 447 Sri Ayudthaya Road, Rachathevi, Bangkok, 10400, Thailand
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362
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363
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Unsaturated Fatty Acids Promote the Phagocytosis of P. aeruginosa and R. equi by RAW264.7 Macrophages. Curr Microbiol 2012; 65:649-55. [DOI: 10.1007/s00284-012-0207-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 08/08/2012] [Indexed: 11/27/2022]
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364
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Formosa C, Grare M, Jauvert E, Coutable A, Regnouf-de-Vains JB, Mourer M, Duval RE, Dague E. Nanoscale analysis of the effects of antibiotics and CX1 on a Pseudomonas aeruginosa multidrug-resistant strain. Sci Rep 2012; 2:575. [PMID: 22893853 PMCID: PMC3418629 DOI: 10.1038/srep00575] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 07/30/2012] [Indexed: 12/02/2022] Open
Abstract
Drug resistance is a challenge that can be addressed using nanotechnology. We focused on the resistance of the bacteria Pseudomonas aeruginosa and investigated, using Atomic Force Microscopy (AFM), the behavior of a reference strain and of a multidrug resistant clinical strain, submitted to two antibiotics and to an innovative antibacterial drug (CX1). We measured the morphology, surface roughness and elasticity of the bacteria under physiological conditions and exposed to the antibacterial molecules. To go further in the molecules action mechanism, we explored the bacterial cell wall nanoscale organization using functionalized AFM tips. We have demonstrated that affected cells have a molecularly disorganized cell wall; surprisingly long molecules being pulled off from the cell wall by a lectin probe. Finally, we have elucidated the mechanism of action of CX1: it destroys the outer membrane of the bacteria as demonstrated by the results on artificial phospholipidic membranes and on the resistant strain.
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Affiliation(s)
- C Formosa
- Centre National de la Recherche Scientifique, Laboratoire d’Analyse et d’Architecture des Systèmes-LAAS, Toulouse, France
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365
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Gong F, Zhan W, Wang L, Song Y, Xing M, Song J. Role of MexA-MexB-OprM efflux pump system in chronic Pseudomonas aeruginosa pulmonary infection in mice. ACTA ACUST UNITED AC 2012; 32:546-551. [PMID: 22886968 DOI: 10.1007/s11596-012-0094-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Indexed: 02/02/2023]
Abstract
In order to investigate the role of the MexA-MexB-OprM efflux pump system in the pathogenesis of Pseudomonas aeruginosa (PA)-induced pulmonary infection, pulmonary infection models were established by intratracheal injection of K767 (wild type), nalB (MexA-MexB-OprM up-regulated mutant), and ΔmexB (knockout) strains, separately. All mice were treated with Meropenem (intraper Δ itoneal injection, 100 mg/kg body weight, twice every day), and strain-related pathology, bacteria count, cytokine level, myeloperoxidase (MPO, indicator of neutrophil recruitment) activity, and macrophage inflammatory protein-2 (MIP-2) expression were evaluated at early (3rd day post-infection) and late (7th and 14th day post-infection) stages of infection. E-test showed that ΔmexB was more significantly Δ sensitive to panipenan (ETP), meropenem (MP) and imipenem (IP) than K767 and nalB strains. There was no significant difference in sensitivity to cefepime (TM) among the three stains. In contrast to the K767 and nalB groups, the ΔmexB group showed decreased bacteria burden over time and less exte Δ nsive pathological change. Additionally, MPO activity and levels of inflammatory cytokines (IL-1b, IL-12, and TNF-α) were increased at the early stage (day 3) and decreased at the later stage (day 14). Serum MIP-2 expression level was steadily increased in all three groups from early to late stages, but significantly higher in ΔmexB group than in K767 and nalB groups ( Δ P<0.05). In conclusion, the MexA-MexB-OprM efflux pump system might play an important role in PA-induced chronic pulmonary infection. High expression of the MexA-MexB-OprM efflux pump could increase antibacterial resistance and promote infection.
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Affiliation(s)
- Fengyun Gong
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Weili Zhan
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Lili Wang
- Department of Respiratory Medicine, Central Hospital of Qingdao, Qingdao, 266042, China
| | - Ying Song
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Mingyou Xing
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Jianxin Song
- Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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366
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Polotto M, Casella T, de Lucca Oliveira MG, Rúbio FG, Nogueira ML, de Almeida MT, Nogueira MC. Detection of P. aeruginosa harboring bla CTX-M-2, bla GES-1 and bla GES-5, bla IMP-1 and bla SPM-1 causing infections in Brazilian tertiary-care hospital. BMC Infect Dis 2012; 12:176. [PMID: 22863113 PMCID: PMC3512492 DOI: 10.1186/1471-2334-12-176] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 07/24/2012] [Indexed: 12/27/2022] Open
Abstract
Background Nosocomial infections caused by Pseudomonas aeruginosa presenting resistance to beta-lactam drugs are one of the most challenging targets for antimicrobial therapy, leading to substantial increase in mortality rates in hospitals worldwide. In this context, P. aeruginosa harboring acquired mechanisms of resistance, such as production of metallo-beta-lactamase (MBLs) and extended-spectrum beta-lactamases (ESBLs) have the highest clinical impact. Hence, this study was designed to investigate the presence of genes codifying for MBLs and ESBLs among carbapenem resistant P. aeruginosa isolated in a Brazilian 720-bed teaching tertiary care hospital. Methods Fifty-six carbapenem-resistant P. aeruginosa strains were evaluated for the presence of MBL and ESBL genes. Strains presenting MBL and/or ESBL genes were submitted to pulsed-field gel electrophoresis for genetic similarity evaluation. Results Despite the carbapenem resistance, genes for MBLs (blaSPM-1 or blaIMP-1) were detected in only 26.7% of isolates. Genes encoding ESBLs were detected in 23.2% of isolates. The blaCTX-M-2 was the most prevalent ESBL gene (19.6%), followed by blaGES-1 and blaGES-5 detected in one isolate each. In all isolates presenting MBL phenotype by double-disc synergy test (DDST), the blaSPM-1 or blaIMP-1 genes were detected. In addition, blaIMP-1 was also detected in three isolates which did not display any MBL phenotype. These isolates also presented the blaCTX-M-2 gene. The co-existence of blaCTX-M-2 with blaIMP-1 is presently reported for the first time, as like as co-existence of blaGES-1 with blaIMP-1. Conclusions In this study MBLs production was not the major mechanism of resistance to carbapenems, suggesting the occurrence of multidrug efflux pumps, reduction in porin channels and production of other beta-lactamases. The detection of blaCTX-M-2,blaGES-1 and blaGES-5 reflects the recent emergence of ESBLs among antimicrobial resistant P. aeruginosa and the extraordinary ability presented by this pathogen to acquire multiple resistance mechanisms. These findings raise the concern about the future of antimicrobial therapy and the capability of clinical laboratories to detect resistant strains, since simultaneous production of MBLs and ESBLs is known to promote further complexity in phenotypic detection. Occurrence of intra-hospital clonal dissemination enhances the necessity of better observance of infection control practices.
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Affiliation(s)
- Milena Polotto
- Laboratório de Microbiologia, Departamento de Doenças Dermatológicas, Infecciosas e Parasitárias, São José do Rio Preto, SP, Brazil
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367
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Fehlberg LC, Xavier DE, Peraro PP, Marra AR, Edmond MB, Gales AC. Beta-Lactam Resistance Mechanisms inPseudomonas aeruginosaStrains Causing Bloodstream Infections: Comparative Results Between Brazilian and American Isolates. Microb Drug Resist 2012; 18:402-7. [DOI: 10.1089/mdr.2011.0174] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Lorena C.C. Fehlberg
- Division of Infectious Diseases, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Danilo E. Xavier
- Division of Infectious Diseases, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Paula P. Peraro
- Division of Infectious Diseases, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Alexandre R. Marra
- Division of Infectious Diseases, Universidade Federal de São Paulo, São Paulo, Brazil
- Intensive Care Unit, Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - Michael B. Edmond
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, Virginia
| | - Ana C. Gales
- Division of Infectious Diseases, Universidade Federal de São Paulo, São Paulo, Brazil
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368
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Reduced expression of the rplU-rpmA ribosomal protein operon in mexXY-expressing pan-aminoglycoside-resistant mutants of pseudomonas aeruginosa. Antimicrob Agents Chemother 2012; 56:5171-9. [PMID: 22825121 DOI: 10.1128/aac.00846-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Pan-aminoglycoside-resistant Pseudomonas aeruginosa mutants expressing the mexXY components of the aminoglycoside-accommodating MexXY-OprM multidrug efflux system but lacking mutations in the mexZ gene encoding a repressor of this efflux system and in the mexXY promoter have been reported (S. Fraud and K. Poole, Antimicrob. Agents Chemother. 55:1068-1074, 2011). Genome sequencing of one of these mutants, K2966, revealed the presence of a mutation within the predicted promoter region of the rplU-rpmA operon encoding ribosomal proteins L21 and L27, consistent with an observed 2-fold decrease in expression of this operon in the mutant relative to wild-type P. aeruginosa PAO1. Moreover, correction of the mutation restored rplU-rpmA expression and, significantly, reversed the elevated mexXY expression and pan-aminoglycoside resistance of the mutant. Reduced rplU-rpmA expression was also observed in a second mexXY-expressing pan-aminoglycoside-resistant mutant, K2968, which, however, lacked a mutation in the rplU-rpmA promoter region. Restoration of rplU-rpmA expression in the K2968 mutant following chromosomal integration of the rplU-rpmA operon derived from wild-type P. aeruginosa failed, however, to reverse the elevated mexXY expression and pan-aminoglycoside resistance of this mutant, although it did so for K2966, suggesting that the mutation impacting rplU-rpmA expression in K2968 also impacts other mexXY-related genes. Increased mexXY expression owing to reduced rplU-rpmA expression in K2966 and K2968 was dependent on PA5471, whose expression was also elevated in these mutants. Thus, mutational disruption of ribosome function, by limiting expression of ribosomal constituents, promotes recruitment of mexXY and does so via PA5471, reminiscent of mexXY induction by ribosome-disrupting antimicrobial agents. Interestingly, reduced rplU-rpmA expression was also observed in a mexXY-expressing pan-aminoglycoside-resistant clinical isolate, suggesting that ribosome-perturbing mutations have clinical relevance in the recruitment of the MexXY-OprM aminoglycoside resistance determinant.
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Fair RJ, Hensler ME, Thienphrapa W, Dam QN, Nizet V, Tor Y. Selectively guanidinylated aminoglycosides as antibiotics. ChemMedChem 2012; 7:1237-44. [PMID: 22639134 PMCID: PMC3383777 DOI: 10.1002/cmdc.201200150] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Indexed: 11/07/2022]
Abstract
The emergence of virulent, drug-resistant bacterial strains coupled with a minimal output of new pharmaceutical agents to combat them makes this a critical time for antibacterial research. Aminoglycosides are a well-studied, highly potent class of naturally occurring antibiotics with scaffolds amenable to modification, and therefore, they provide an excellent starting point for the development of semisynthetic, next-generation compounds. To explore the potential of this approach, we synthesized a small library of aminoglycoside derivatives selectively and minimally modified at one or two positions with a guanidine group replacing the corresponding amine or hydroxy functionality. Most guanidino-aminoglycosides showed increased affinity for the ribosomal decoding rRNA site, the cognate biological target of the natural products, when compared with their parent antibiotics, as measured by an in vitro fluorescence resonance energy transfer (FRET) A-site binding assay. Additionally, certain analogues showed improved minimum inhibitory concentration (MIC) values against resistant bacterial strains, including methicillin-resistant Staphylococcus aureus (MRSA). An amikacin derivative holds particular promise with activity greater than or equal to the parent antibiotic in the majority of bacterial strains tested.
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Affiliation(s)
- Richard J. Fair
- Department of Chemistry & Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (USA)
| | - Mary E. Hensler
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (USA)
| | - Wdee Thienphrapa
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (USA)
| | - Quang N. Dam
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (USA)
| | - Victor Nizet
- Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (USA)
| | - Yitzhak Tor
- Department of Chemistry & Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (USA)
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370
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Duration of hospital admission and the need for empirical antipseudomonal therapy. J Clin Microbiol 2012; 50:2695-701. [PMID: 22675131 DOI: 10.1128/jcm.00758-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To reduce selective pressure for antimicrobial resistance, empirical use of antipseudomonal antibiotics is often reserved for patients with late-onset hospital-acquired infections. We examined the likelihood of isolating Pseudomonas aeruginosa as a function of time from hospital admission. We conducted a retrospective cohort study of all positive bacterial cultures in a tertiary-care hospital between March 2010 and November 2011. The primary outcome was the proportion of positive cultures yielding P. aeruginosa. Multivariable logistic regression was employed to assess the impact of time from admission on the likelihood of isolating P. aeruginosa, after adjusting for other important risk factors. A total of 7,668 positive cultures were obtained from 4,108 unique patients during the study interval, including 633 (8.3%) yielding P. aeruginosa. The probability of isolating P. aeruginosa increased linearly from 79/2,044 (3.9%) positive cultures obtained on admission to 153/664 (23%) in the 10th week of admission or beyond. The unadjusted odds ratio was 1.002/day (95% confidence interval [CI], 1.0016 to 1.0028; P < 0.0001); the adjusted odds ratio (aOR) was 1.0007/day (95% CI, 1.0001 to 1.0013; P = 0.02). Other important predictors of P. aeruginosa isolation included respiratory specimen type (aOR, 13.8; 95% CI, 9.1 to 21.1), recent hospital admission (aOR,1.8; 95% CI, 1.4 to 2.3), prior P. aeruginosa isolation during current admission (aOR, 4.9; 95% CI, 3.7 to 6.4), and prior antipseudomonal (aOR, 1.9; 95% CI, 1.4 to 2.5) or nonantipseudomonal (aOR, 1.8; 95% CI, 1.4 to 2.4) antibiotic exposure. It was determined that as time from admission increases, there is a linear increase in the likelihood of P. aeruginosa isolation. Any guidelines which distinguish early from late hospital-acquired infection must consider the implications of time point selection on the likelihood of inadequate P. aeruginosa empirical coverage.
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371
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Adolph S, Schoeniger A, Fuhrmann H, Schumann J. Unsaturated fatty acids as modulators of macrophage respiratory burst in the immune response against Rhodococcus equi and Pseudomonas aeruginosa. Free Radic Biol Med 2012; 52:2246-53. [PMID: 22658994 DOI: 10.1016/j.freeradbiomed.2012.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 03/23/2012] [Accepted: 04/02/2012] [Indexed: 10/28/2022]
Abstract
In this paper, using the monocyte/macrophage cell line RAW264.7, we systematically investigate the impact of macrophage enrichment with unsaturated fatty acids on cellular radical synthesis. We found that the intracellular production of reactive nitrogen and oxygen intermediates depends on the activation status of the macrophages. For unstimulated macrophages PUFA enrichment resulted in an increase in cellular radical synthesis. For stimulated macrophages, instead, an impeding action of unsaturated fatty acids on the respiratory burst could be seen. Of particular importance, the impact of unsaturated fatty acids on the macrophage respiratory burst was also observed in RAW264.7 cells cocultivated with viable bacteria of the species Rhodococcus equi or Pseudomonas aeruginosa. PUFA supplementation of macrophages in the presence of R. equi or P. aeruginosa reduced the pathogen-stimulated synthesis of reactive nitrogen and oxygen intermediates. Furthermore, the unsaturated fatty acids were found to impede the expression of the myeloperoxidase gene and to reduce the activity of the enzyme. Hence, our data provide indications of a possible value of PUFA application to people suffering from chronic infections with R. equi and P. aeruginosa as a concomitant treatment to attenuate an excessive respiratory burst.
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Affiliation(s)
- Stephanie Adolph
- Faculty of Veterinary Medicine, Institute of Physiological Chemistry, University of Leipzig, 04103 Leipzig, Germany
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372
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Vaz-Moreira I, Nunes OC, Manaia CM. Diversity and antibiotic resistance in Pseudomonas spp. from drinking water. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 426:366-74. [PMID: 22521167 DOI: 10.1016/j.scitotenv.2012.03.046] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 03/19/2012] [Accepted: 03/20/2012] [Indexed: 05/06/2023]
Abstract
Pseudomonas spp. are common inhabitants of aquatic environments, including drinking water. Multi-antibiotic resistance in clinical isolates of P. aeruginosa is widely reported and deeply characterized. However, the information regarding other species and environmental isolates of this genus is scant. This study was designed based on the hypothesis that members of the genus Pseudomonas given their high prevalence, wide distribution in waters and genetic plasticity can be important reservoirs of antibiotic resistance in drinking water. With this aim, the diversity and antibiotic resistance phenotypes of Pseudomonas isolated from different drinking water sources were evaluated. The genotypic diversity analyses were based on six housekeeping genes (16S rRNA, rpoD, rpoB, gyrB, recA and ITS) and on pulsed field gel electrophoresis. Susceptibility to 21 antibiotics of eight classes was tested using the ATB PSE EU (08) and disk diffusion methods. Pseudomonas spp. were isolated from 14 of the 32 sampled sites. A total of 55 non-repetitive isolates were affiliated to twenty species. Although the same species were isolated from different sampling sites, identical genotypes were never observed in distinct types of water (water treatment plant/distribution system, tap water, cup fillers, biofilm, and mineral water). In general, the prevalence of antibiotic resistance was low and often the resistance patterns were related with the species and/or the strain genotype. Resistance to ticarcillin, ticarcillin with clavulanic acid, fosfomycin and cotrimoxazol were the most prevalent (69-84%). No resistance to piperacillin, levofloxacin, ciprofloxacin, tetracycline, gentamicin, tobramycin, amikacin, imipenem or meropenem was observed. This study demonstrates that Pseudomonas spp. are not so widespread in drinking water as commonly assumed. Nevertheless, it suggests that water Pseudomonas can spread acquired antibiotic resistance, preferentially via vertical transmission.
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Affiliation(s)
- Ivone Vaz-Moreira
- CBQF/Escola Superior de Biotecnologia, Universidade Católica Portuguesa, 4200-072 Porto, Portugal
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373
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The transcriptional regulator CzcR modulates antibiotic resistance and quorum sensing in Pseudomonas aeruginosa. PLoS One 2012; 7:e38148. [PMID: 22666466 PMCID: PMC3362554 DOI: 10.1371/journal.pone.0038148] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 04/30/2012] [Indexed: 11/20/2022] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa responds to zinc, cadmium and cobalt by way of the CzcRS two-component system. In presence of these metals the regulatory protein CzcR induces the expression of the CzcCBA efflux pump, expelling and thereby inducing resistance to Zn, Cd and Co. Importantly, CzcR co-regulates carbapenem antibiotic resistance by repressing the expression of the OprD porin, the route of entry for these antibiotics. This unexpected co-regulation led us to address the role of CzcR in other cellular processes unrelated to the metal response. We found that CzcR affected the expression of numerous genes directly involved in the virulence of P. aeruginosa even in the absence of the inducible metals. Notably the full expression of quorum sensing 3-oxo-C12-HSL and C4-HSL autoinducer molecules is impaired in the absence of CzcR. In agreement with this, the virulence of the czcRS deletion mutant is affected in a C. elegans animal killing assay. Additionally, chromosome immunoprecipitation experiments allowed us to localize CzcR on the promoter of several regulated genes, suggesting a direct control of target genes such as oprD, phzA1 and lasI. All together our data identify CzcR as a novel regulator involved in the control of several key genes for P. aeruginosa virulence processes.
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374
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Cavalcanti FLDS, Almeida ACS, Vilela MA, Morais MMCD, Morais Junior MAD. Changing the epidemiology of carbapenem-resistant Pseudomonas aeruginosa in a Brazilian teaching hospital: the replacement of São Paulo metallo-β-lactamase-producing isolates. Mem Inst Oswaldo Cruz 2012; 107:420-3. [DOI: 10.1590/s0074-02762012000300019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 11/29/2011] [Indexed: 11/22/2022] Open
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375
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Santoro DO, Romão CMCA, Clementino MM. Decreased aztreonam susceptibility among Pseudomonas aeruginosa isolates from hospital effluent treatment system and clinical samples. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2012; 22:560-570. [PMID: 22540159 DOI: 10.1080/09603123.2012.678000] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The aim of this study was to evaluate the antimicrobial resistance patterns of Pseudomonas aeruginosa isolates from hospital wastewater treatment system (HWTS) and clinical specimens in a hospital of Rio de Janeiro city, Brazil. Forty-three isolates obtained from four of the five steps of the HWTS (n = 27) and clinical samples (n = 16) from patients were analyzed regarding their susceptibility profiles to 12 antibiotics. Clinical isolates exhibited higher resistance profiles to antibiotics than wastewater isolates. However, out of 27 isolates from sewage, 62.9% showed decreased susceptibility to aztreonam while 50% of clinical isolates were resistant to this antibiotic. Isolates were not detected at the chlorination stage but they were obtained from the following stage of the treatment revealing the capacity of regrowth after chlorinated sewage effluent. To our knowledge, this is the first study reporting decreased aztreonam susceptibility among P. aeruginosa isolates from a hospital wastewater treatment system. Further investigations are being conducted by our laboratory including a larger sampling program in order to obtain more data.
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Affiliation(s)
- Deborah O Santoro
- Department of Microbiology, National Institute of Quality Control in Health, Fiocruz, Rio de Janeiro, Brazil
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376
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The Potential of Frog Skin Antimicrobial Peptides for Development into Therapeutically Valuable Anti-Infective Agents. ACTA ACUST UNITED AC 2012. [DOI: 10.1021/bk-2012-1095.ch003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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377
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Harada K, Arima S, Niina A, Kataoka Y, Takahashi T. Characterization of Pseudomonas aeruginosa isolates from dogs and cats in Japan: current status of antimicrobial resistance and prevailing resistance mechanisms. Microbiol Immunol 2012; 56:123-7. [DOI: 10.1111/j.1348-0421.2011.00416.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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378
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Beta-lactams resistance and presence of class 1 integron in Pseudomonas spp. isolated from untreated hospital effluents in Brazil. Antonie van Leeuwenhoek 2012; 102:73-81. [DOI: 10.1007/s10482-012-9714-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 02/20/2012] [Indexed: 10/28/2022]
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379
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Infrequent finding of metallo-β-lactamase VIM-2 in carbapenem-resistant Pseudomonas aeruginosa strains from Croatia. Antimicrob Agents Chemother 2012; 56:2746-9. [PMID: 22371893 DOI: 10.1128/aac.05212-11] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One hundred sixty-nine nonreplicate imipenem-resistant Pseudomonas aeruginosa strains isolated in a large hospital on the coastal region of Croatia were studied. The most active antibiotics were colistin and amikacin. Most of the isolates were multiresistant. The most prevalent serotype was O12, followed by O11. Six strains carried the bla(VIM-2) gene located in a novel class 1 integron composed in its variable part of the bla(VIM-2)-bla(oxa-10)-ΔqacF-aacA4 genes. Metallo-β-lactamase-producing strains belonged to sequence types ST235 and ST111.
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380
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[Detection of extended spectrum β-lactamase OXA-141 in Pseudomonas aeruginosa strains isolated from patients with cystic fibrosis]. Enferm Infecc Microbiol Clin 2012; 30:535-41. [PMID: 22365474 DOI: 10.1016/j.eimc.2012.01.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 12/13/2011] [Accepted: 01/01/2012] [Indexed: 11/22/2022]
Abstract
INTRODUCTION The aims of this research were to study the presence of extended spectrum β-lactamases (ESBL) to investigate the location of the genes encoding these enzymes, and determine the clonal relationship of strains of ceftazidime-resistant Pseudomonas aeruginosa isolated from Mexican patients with cystic fibrosis. METHODS We determined the resistance profile to 11 antibiotics (CLSI) and phenotypic ESBL detection following a disk diffusion method adapted for P. aeruginosa. Characterization of ESBL genes and integrons was performed by polymerase chain reaction (PCR) and DNA sequencing, while analysis of the clonal relationship was performed by pulsed field gel electrophoresis (PFGE). RESULTS Of the 148 strains studied, 22 were resistant to ceftazidime, and analysis by PCR and sequencing revealed the presence of the gene bla(OXA-141) in 7 strains, 6 of which were resistant and one, susceptible to ceftazidime. In addition, bla(GES) was detected in 11 strains. intI2 and intI3 genes were not detected by PCR, but in the 6 ceftazidime-resistant strains, the bla(OXA-141) gene was determined in a class 1 integron. Analysis of the clonal relationship of isolates showed that the majority of patients were infected during the study period with P. aeruginosa strains that exhibit different patterns, especially in individuals without a familial relationship. CONCLUSIONS This report demonstrates the existence of the bla(OXA-141) gene associated with a class 1 integron in several strains of P. aeruginosa, as well as bla(GES) genes, and their location and variants are being studied by our research group. This, combined with the diversity of strains able to infect several susceptible individuals, suggests the risk of spread of P. aeruginosa-strain ESBL producers among Mexican populations with cystic fibrosis.
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381
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LiF Reduces MICs of Antibiotics against Clinical Isolates of Gram-Positive and Gram-Negative Bacteria. Int J Microbiol 2012; 2012:454065. [PMID: 22518143 PMCID: PMC3299231 DOI: 10.1155/2012/454065] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 12/16/2011] [Indexed: 11/22/2022] Open
Abstract
Antibiotic resistance is an ever-growing problem yet the development of new antibiotics has slowed to a trickle, giving rise to the use of combination therapy to eradicate infections. The purpose of this study was to evaluate the combined inhibitory effect of lithium fluoride (LiF) and commonly used antimicrobials on the growth of the following bacteria: Enterococcus faecalis, Staphyloccoccus aureus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Serratia marcescens, and Streptococcus pneumoniae. The in vitro activities of ceftazidime, sulfamethoxazole-trimethoprim, streptomycin, erythromycin, amoxicillin, and ciprofloxacin, doxycycline, alone or combined with LiF were performed by microdilution method. MICs were determined visually following 18–20 h of incubation at 37°C. We observed reduced MICs of antibiotics associated with LiF ranging from two-fold to sixteen-fold. The strongest decreases of MICs observed were for streptomycin and erythromycin associated with LiF against Acinetobacter baumannii and Streptococcus pneumoniae. An eight-fold reduction was recorded for streptomycin against S. pneumoniae whereas an eight-fold and a sixteen-fold reduction were obtained for erythromycin against A. baumannii and S. pneumoniae. This suggests that LiF exhibits a synergistic effect with a wide range of antibiotics and is indicative of its potential as an adjuvant in antibiotic therapy.
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382
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Abstract
The specific aminoacylation of the phospholipid phosphatidylglycerol (PG) with alanine or with lysine catalyzed by aminoacyl-phosphatidylglycerol synthases (aaPGS) was shown to render various organisms less susceptible to antibacterial agents. This study makes use of Pseudomonas aeruginosa chimeric mutant strains producing lysyl-phosphatidylglycerol (L-PG) instead of the naturally occurring alanyl-phosphatidylglycerol (A-PG) to study the resulting impact on bacterial resistance. Consequences of such artificial phospholipid composition were studied in the presence of an overall of seven antimicrobials (β-lactams, a lipopeptide antibiotic, cationic antimicrobial peptides [CAMPs]) to quantitatively assess the effect of A-PG substitution (with L-PG, L-PG and A-PG, increased A-PG levels). For the employed Gram-negative P. aeruginosa model system, an exclusive charge repulsion mechanism does not explain the attenuated antimicrobial susceptibility due to PG modification. Additionally, the specificity of nine orthologous aaPGS enzymes was experimentally determined. The newly characterized protein sequences allowed for the establishment of a significant group of A-PG synthase sequences which were bioinformatically compared to the related group of L-PG synthesizing enzymes. The analysis revealed a diverse origin for the evolution of A-PG and L-PG synthases, as the specificity of an individual enzyme is not reflected in terms of a characteristic sequence motif. This finding is relevant for future development of potential aaPGS inhibitors.
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383
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Wang W, Monlezun L, Picard M, Benas P, Français O, Broutin I, Le Pioufle B. Activity monitoring of functional OprM using a biomimetic microfluidic device. Analyst 2012; 137:847-52. [PMID: 22215439 DOI: 10.1039/c2an16007b] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
This paper describes the fabrication and use of a biomimetic microfluidic device for the monitoring of a functional porin reconstituted within a miniaturized suspended artificial bilayer lipid membrane (BLM). Such a microfluidic device allows for (1) fluidic and electrical access to both sides of the BLM and (2) reproducible membrane protein insertion and long-term electrical monitoring of its conductance (G(i)), thanks to the miniaturization of the BLM. We demonstrate here for the first time the feasibility to insert a large trans-membrane protein through its β-barrel, and monitor its functional activity for more than 1 hour (limited by buffer evaporation). In this paper, we specifically used our device for the monitoring of OprM, a bacterial efflux channel involved in the multidrug resistance of the bacteria Pseudomonas aeruginosa. Sub-steps of the OprM channel conductance were detected during the electrical recordings within our device, which might be due to oscillations between several structural conformations (sub-states) adopted by the protein, as part of its opening mechanism. This work is a first step towards the establishment of a genuine platform dedicated to the investigation of bacterial proteins under reconstituted conditions, a very promising tool for the screening of new inhibitors against bacterial channels involved in drug resistance.
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Affiliation(s)
- Wei Wang
- SATIE, UMR 8029 CNRS, Ecole Normale Supérieure de Cachan, 61 Avenue du Président Wilson, 94235, Cachan Cedex, France
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384
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BVPaP-3, a T7-Like Lytic Phage of Pseudomonas aeruginosa: Its Isolation and Characterisation. Curr Microbiol 2012; 64:305-11. [DOI: 10.1007/s00284-011-0071-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 12/14/2011] [Indexed: 10/14/2022]
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385
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Formosa C, Grare M, Duval RE, Dague E. Nanoscale effects of antibiotics on P. aeruginosa. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2012; 8:12-6. [DOI: 10.1016/j.nano.2011.09.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 09/15/2011] [Accepted: 09/20/2011] [Indexed: 10/16/2022]
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386
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Yamachika S, Sugihara C, Tsuji H, Muramatsu Y, Kamai Y, Yamashita M. Anti- Pseudomonas aeruginosa Compound, 1,2,3,4-Tetrahydro-1,3,5-triazine Derivative, Exerts Its Action by Primarily Targeting MreB. Biol Pharm Bull 2012; 35:1740-4. [DOI: 10.1248/bpb.b12-00397] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
| | - Chika Sugihara
- Lead Discovery & Optimization Research Laboratories II, Daiichi Sankyo Co., Ltd
| | - Hayato Tsuji
- Lead Discovery & Optimization Research Laboratories II, Daiichi Sankyo Co., Ltd
| | - Yasunori Muramatsu
- Lead Discovery & Optimization Research Laboratories II, Daiichi Sankyo Co., Ltd
| | - Yasuki Kamai
- Oncology Research Laboratories, Daiichi Sankyo Co., Ltd
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387
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Topal H, Fulcher NB, Bitterman J, Salazar E, Buck J, Levin LR, Cann MJ, Wolfgang MC, Steegborn C. Crystal structure and regulation mechanisms of the CyaB adenylyl cyclase from the human pathogen Pseudomonas aeruginosa. J Mol Biol 2011; 416:271-86. [PMID: 22226839 DOI: 10.1016/j.jmb.2011.12.045] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 12/18/2011] [Accepted: 12/21/2011] [Indexed: 12/15/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic bacterial pathogen and a major cause of healthcare-associated infections. While the organism's intrinsic and acquired resistance to most antibiotics hinders treatment of P. aeruginosa infections, the regulatory networks controlling its virulence provide novel targets for drug development. CyaB, a key regulator of P. aeruginosa virulence, belongs to the Class III adenylyl cyclase (AC) family of enzymes that synthesize the second messenger cyclic adenosine 3',5'-monophosphate. These enzymes consist of a conserved catalytic domain fused to one or more regulatory domains. We describe here the biochemical and structural characterization of CyaB and its inhibition by small molecules. We show that CyaB belongs to the Class IIIb subfamily, and like other subfamily members, its activity is stimulated by inorganic carbon. CyaB is also regulated by its N-terminal MASE2 (membrane-associated sensor 2) domain, which acts as a membrane anchor. Using a genetic screen, we identified activating mutations in CyaB. By solving the crystal structure of the CyaB catalytic domain, we rationalized the effects of these mutations and propose that CyaB employs regulatory mechanisms similar to other Class III ACs. The CyaB structure further indicates subtle differences compared to other Class III ACs in both the active site and the inhibitor binding pocket. Consistent with these differences, we observed a unique inhibition profile, including identification of a CyaB selective compound. Overall, our results reveal mechanistic details of the physiological and pharmacological regulation of CyaB and provide the basis for its exploitation as a therapeutic drug target.
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Affiliation(s)
- Hüsnü Topal
- Department of Physiological Chemistry, Ruhr-University Bochum, 44801 Bochum, Germany
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388
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Novel NADPH-cysteine covalent adduct found in the active site of an aldehyde dehydrogenase. Biochem J 2011; 439:443-52. [PMID: 21732915 DOI: 10.1042/bj20110376] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PaBADH (Pseudomonas aeruginosa betaine aldehyde dehydrogenase) catalyses the irreversible NAD(P)+-dependent oxidation of betaine aldehyde to its corresponding acid, the osmoprotector glycine betaine. This reaction is involved in the catabolism of choline and in the response of this important pathogen to the osmotic and oxidative stresses prevalent in infection sites. The crystal structure of PaBADH in complex with NADPH showed a novel covalent adduct between the C2N of the pyridine ring and the sulfur atom of the catalytic cysteine residue, Cys286. This kind of adduct has not been reported previously either for a cysteine residue or for a low-molecular-mass thiol. The Michael addition of the cysteine thiolate in the 'resting' conformation to the double bond of the α,β-unsaturated nicotinamide is facilitated by the particular conformation of NADPH in the active site of PaBADH (also observed in the crystal structure of the Cys286Ala mutant) and by an ordered water molecule hydrogen bonded to the carboxamide group. Reversible formation of NAD(P)H-Cys286 adducts in solution causes reversible enzyme inactivation as well as the loss of Cys286 reactivity towards thiol-specific reagents. This novel covalent modification may provide a physiologically relevant regulatory mechanism of the irreversible PaBADH-catalysed reaction, preventing deleterious decreases in the intracellular NAD(P)+/NAD(P)H ratios.
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389
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Florescu DF, Grant W, Botha JF, Fey P, Kalil AC. Should multivisceral transplantation be considered in patients colonized with multidrug-resistant Pseudomonas aeruginosa? Microb Drug Resist 2011; 18:74-8. [PMID: 22107253 DOI: 10.1089/mdr.2011.0099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This report describes two subsequent liver-small bowel-pancreas-kidney (multivisceral) transplantations in a child colonized with multidrug-resistant Pseudomonas aeruginosa. We discuss the dilemma concerning the transplantation of patients colonized with multidrug-resistant Pseudomonas spp., its potential consequences, and the peri and postoperative management of these patients.
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Affiliation(s)
- Diana F Florescu
- Transplant Infectious Diseases Program, Infectious Diseases Division, University of Nebraska Medical Center, Omaha, Nebraska NE 68198-5400, USA.
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390
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The impact of membrane lipid composition on macrophage activation in the immune defense against Rhodococcus equi and Pseudomonas aeruginosa. Int J Mol Sci 2011; 12:7510-28. [PMID: 22174614 PMCID: PMC3233420 DOI: 10.3390/ijms12117510] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/17/2011] [Accepted: 10/26/2011] [Indexed: 11/29/2022] Open
Abstract
Nutritional fatty acids are known to have an impact on membrane lipid composition of body cells, including cells of the immune system, thus providing a link between dietary fatty acid uptake, inflammation and immunity. In this study we reveal the significance of macrophage membrane lipid composition on gene expression and cytokine synthesis thereby highlighting signal transduction processes, macrophage activation as well as macrophage defense mechanisms. Using RAW264.7 macrophages as a model system, we identified polyunsaturated fatty acids (PUFA) of both the n-3 and the n-6 family to down-regulate the synthesis of: (i) the pro-inflammatory cytokines IL-1β, IL-6 and TNF-α; (ii) the co-stimulatory molecule CD86; as well as (iii) the antimicrobial polypeptide lysozyme. The action of the fatty acids partially depended on the activation status of the macrophages. It is particularly important to note that the anti-inflammatory action of the PUFA could also be seen in case of infection of RAW264.7 with viable microorganisms of the genera R. equi and P. aeruginosa. In summary, our data provide strong evidence that PUFA from both the n-3 and the n-6 family down-regulate inflammation processes in context of chronic infections caused by persistent pathogens.
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391
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Gillanders LJ, Elborn JS, Gilpin DF, Schneiders T, Tunney MM. The airway microbiome in cystic fibrosis: challenges for therapy. ACTA ACUST UNITED AC 2011. [DOI: 10.2217/thy.11.81] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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392
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Abstract
Several disease states create conditions that lead to opportunistic Gram-negative respiratory infections. Inhalation is the most direct and, until recently, underutilized means of antimicrobial drug targeting for respiratory tract infections. All approved antimicrobial agents for administration by inhalation are indicated for Pseudomonas aeruginosa infections in patients with cystic fibrosis. These inhaled therapies have directly contributed to a significant reduction in exacerbations and hospitalizations in this patient population over the last few decades. The relentless adaptation of pathogenic organisms to current treatment options demands that the pharmaceutical industry continue designing next-generation antimicrobial agents over 70 years after they were first introduced. Recent technological advances in inhalation devices and drug formulation techniques have broadened the scope of antimicrobial structural classes that can be investigated by inhalation; however, there is an urgent need to discover novel compounds with improved resistance profiles relative to those drugs that are already marketed.
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393
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El Houry Mignan S, Witte G, Naue N, Curth U. Characterization of the χψ subcomplex of Pseudomonas aeruginosa DNA polymerase III. BMC Mol Biol 2011; 12:43. [PMID: 21955458 PMCID: PMC3197488 DOI: 10.1186/1471-2199-12-43] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 09/28/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND DNA polymerase III, the main enzyme responsible for bacterial DNA replication, is composed of three sub-assemblies: the polymerase core, the β-sliding clamp, and the clamp loader. During replication, single-stranded DNA-binding protein (SSB) coats and protects single-stranded DNA (ssDNA) and also interacts with the χψ heterodimer, a sub-complex of the clamp loader. Whereas the χ subunits of Escherichia coli and Pseudomonas aeruginosa are about 40% homologous, P. aeruginosa ψ is twice as large as its E. coli counterpart, and contains additional sequences. It was shown that P. aeruginosa χψ together with SSB increases the activity of its cognate clamp loader 25-fold at low salt. The E. coli clamp loader, however, is insensitive to the addition of its cognate χψ under similar conditions. In order to find out distinguishing properties within P. aeruginosa χψ which account for this higher stimulatory effect, we characterized P. aeruginosa χψ by a detailed structural and functional comparison with its E. coli counterpart. RESULTS Using small-angle X-ray scattering, analytical ultracentrifugation, and homology-based modeling, we found the N-terminus of P. aeruginosa ψ to be unstructured. Under high salt conditions, the affinity of the χψ complexes from both organisms to their cognate SSB was similar. Under low salt conditions, P. aeruginosa χψ, contrary to E. coli χψ, binds to ssDNA via the N-terminus of ψ. Whereas it is also able to bind to double-stranded DNA, the affinity is somewhat reduced. CONCLUSIONS The binding to DNA, otherwise never reported for any other ψ protein, enhances the affinity of P. aeruginosa χψ towards the SSB/ssDNA complex and very likely contributes to the higher stimulatory effect of P. aeruginosa χψ on the clamp loader. We also observed DNA-binding activity for P. putida χψ, making this activity most probably a characteristic of the ψ proteins from the Pseudomonadaceae.
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Affiliation(s)
- Sirine El Houry Mignan
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Gregor Witte
- Department of Biochemistry, Gene Center of the Ludwig-Maximilians-University Munich, Feodor-Lynen-Str. 25, D-81377 Munich, Germany
- Center for Integrated Protein Sciences (CIPSM), Gene Center of the Ludwig-Maximilians-University Munich, Feodor-Lynen-Str. 25, D-81377 Munich, Germany
- Munich Center for Advanced Photonics (MAP), Gene Center of the Ludwig-Maximilians-University Munich, Feodor-Lynen-Str. 25, D-81377 Munich, Germany
| | - Natalie Naue
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Ute Curth
- Institute for Biophysical Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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394
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Lamarche MG, Déziel E. MexEF-OprN efflux pump exports the Pseudomonas quinolone signal (PQS) precursor HHQ (4-hydroxy-2-heptylquinoline). PLoS One 2011; 6:e24310. [PMID: 21957445 PMCID: PMC3177830 DOI: 10.1371/journal.pone.0024310] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 08/08/2011] [Indexed: 11/19/2022] Open
Abstract
Bacterial cells have evolved the capacity to communicate between each other via small diffusible chemical signals termed autoinducers. Pseudomonas aeruginosa is an opportunistic pathogen involved, among others, in cystic fibrosis complications. Virulence of P. aeruginosa relies on its ability to produce a number of autoinducers, including 4-hydroxy-2-alkylquinolines (HAQ). In a cell density-dependent manner, accumulated signals induce the expression of multiple targets, especially virulence factors. This phenomenon, called quorum sensing, promotes bacterial capacity to cause disease. Furthermore, P. aeruginosa possesses many multidrug efflux pumps conferring adaptive resistance to antibiotics. Activity of some of these efflux pumps also influences quorum sensing. The present study demonstrates that the MexEF-OprN efflux pump modulates quorum sensing through secretion of a signalling molecule belonging to the HAQ family. Moreover, activation of MexEF-OprN reduces virulence factor expression and swarming motility. Since MexEF-OprN can be activated in infected hosts even in the absence of antibiotic selective pressure, it could promote establishment of chronic infections in the lungs of people suffering from cystic fibrosis, thus diminishing the immune response to virulence factors. Therapeutic drugs that affect multidrug efflux pumps and HAQ-mediated quorum sensing would be valuable tools to shut down bacterial virulence.
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Affiliation(s)
| | - Eric Déziel
- INRS-Institut Armand-Frappier, Laval, Québec, Canada
- * E-mail:
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395
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Antibiotic and metal resistance among hospital and outdoor strains of Pseudomonas aeruginosa. Res Microbiol 2011; 162:689-700. [DOI: 10.1016/j.resmic.2011.06.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2010] [Accepted: 05/10/2011] [Indexed: 11/24/2022]
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396
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Influence of Pseudomonas aeruginosa pvdQ gene on altering antibiotic susceptibility under swarming conditions. Curr Microbiol 2011; 63:377-86. [PMID: 21833667 DOI: 10.1007/s00284-011-9979-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 06/24/2011] [Indexed: 10/17/2022]
Abstract
In Pseudomonas aeruginosa PAO1, the pvdQ gene has been shown to have at least two functions. It encodes the acylase enzyme and hydrolyzes 3-oxo-C12-HSL, the key signaling molecule of quorum sensing system. In addition, pvdQ is involved in swarming motility. It is required for up-regulated during swarming motility, which is triggered by high cell densities. As high-density bacterial populations also display elevated antibiotic resistance, studies have demonstrated that swarm-cell differentiation in P. aeruginosa promotes increased resistance to various antibiotics. PvdQ acts as a signal during swarm-cell differentiation, and thus may play a role in P. aeruginosa antibiotic resistance. The aim of this study is to examine whether pvdQ was involved in modifying antibiotic susceptibility during swarming conditions, and to investigate the mechanism by which this occurred. We constructed the PAO1pMEpvdQ strain, which overproduced PvdQ. PAO1pMEpvdQ promotes swarming motility, while PAO1ΔpvdQ abolishes swarming motility. In addition, both PAO1 and PAO1pMEpvdQ acquired resistance to ceftazidime, ciprofloxacin, meropenem, polymyxin B, and gentamicin, though PAO1pMEpvdQ exhibited a two to eightfold increase in antibiotic resistance compared to PAO1. These results indicate that pvdQ plays an important role in elevating antibiotic resistance via swarm-cell differentiation and possibly other mechanisms as well. We analyzed outer membrane permeability. Our data also suggest that pvdQ decreases P. aeruginosa outer membrane permeability, thereby elevating antibiotic resistance under swarming conditions. Our results suggest new approaches for reducing P. aeruginosa resistance.
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397
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Abstract
Pseudomonas aeruginosa is intrinsically resistant to a variety of antimicrobials and can develop resistance during anti-pseudomonal chemotherapy both of which compromise treatment of infections caused by this organism. Resistance to multiple classes of antimicrobials (multidrug resistance) in particular is increasingly common in P. aeruginosa, with a number of reports of pan-resistant isolates treatable with a single agent, colistin. Acquired resistance in this organism is multifactorial and attributable to chromosomal mutations and the acquisition of resistance genes via horizontal gene transfer. Mutational changes impacting resistance include upregulation of multidrug efflux systems to promote antimicrobial expulsion, derepression of ampC, AmpC alterations that expand the enzyme's substrate specificity (i.e., extended-spectrum AmpC), alterations to outer membrane permeability to limit antimicrobial entry and alterations to antimicrobial targets. Acquired mechanisms contributing to resistance in P. aeruginosa include β-lactamases, notably the extended-spectrum β-lactamases and the carbapenemases that hydrolyze most β-lactams, aminoglycoside-modifying enzymes, and 16S rRNA methylases that provide high-level pan-aminoglycoside resistance. The organism's propensity to grow in vivo as antimicrobial-tolerant biofilms and the occurrence of hypermutator strains that yield antimicrobial resistant mutants at higher frequency also compromise anti-pseudomonal chemotherapy. With limited therapeutic options and increasing resistance will the untreatable P. aeruginosa infection soon be upon us?
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Affiliation(s)
- Keith Poole
- Department of Microbiology and Immunology, Queen's University Kingston, ON, Canada
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398
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Hare NJ, Scott NE, Shin EHH, Connolly AM, Larsen MR, Palmisano G, Cordwell SJ. Proteomics of the oxidative stress response induced by hydrogen peroxide and paraquat reveals a novel AhpC-like protein in Pseudomonas aeruginosa. Proteomics 2011; 11:3056-69. [DOI: 10.1002/pmic.201000807] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 03/01/2011] [Accepted: 03/07/2011] [Indexed: 12/26/2022]
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399
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Schulz R, Vargiu AV, Ruggerone P, Kleinekathöfer U. Role of Water during the Extrusion of Substrates by the Efflux Transporter AcrB. J Phys Chem B 2011; 115:8278-87. [DOI: 10.1021/jp200996x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Robert Schulz
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen,
Germany
| | - Attilio V. Vargiu
- CNR-IOM, Unità SLACS,
c/o Dipartimento di Fisica, Università di Cagliari, s.p. Monserrato-Sestu km 0.7, I-09042 Monserrato (CA), Italy
| | - Paolo Ruggerone
- CNR-IOM, Unità SLACS,
c/o Dipartimento di Fisica, Università di Cagliari, s.p. Monserrato-Sestu km 0.7, I-09042 Monserrato (CA), Italy
| | - Ulrich Kleinekathöfer
- School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen,
Germany
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400
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Effect of ciprofloxacin concentration on the frequency and nature of resistant mutants selected from Pseudomonas aeruginosa mutS and mutT hypermutators. Antimicrob Agents Chemother 2011; 55:3668-76. [PMID: 21646492 DOI: 10.1128/aac.01826-10] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The rapid emergence of drug resistance upon treatment of Pseudomonas aeruginosa infections with fluoroquinolones is a serious concern. In this study, we report the effect of hypermutability on the mutant selection window for ciprofloxacin (CIP) by comparing the hypermutator MPAO1 mutS and mutT strains with the wild-type strain. The mutant selection window was shifted to higher CIP concentrations for both hypermutators, presenting the mutS strain with a broader selection window in comparison to the wild-type strain. The mutation prevention concentrations (MPC) determined for mutT and mutS strains were increased 2- and 4-fold over the wild-type level, respectively. In addition, we analyzed the molecular bases for resistance in the bacterial subpopulations selected at different points in the window. At the top of the window, the resistant clones isolated were mainly mutated in GyrA and ParC topoisomerase subunits, while at the bottom of the window, resistance was associated with the overexpression of MexCD-OprJ and MexAB-OprM efflux pumps. Accordingly, a greater proportion of multidrug-resistant clones were found among the subpopulations isolated at the lower CIP concentrations. Furthermore, we found that the exposure to CIP subinhibitory concentrations favors the accumulation of cells overexpressing MexCD-OprJ (due to mutations in the transcriptional repressor NfxB) and MexAB-OprM efflux pumps. We discuss these results in the context of the possible participation of this antibiotic in a mutagenic process.
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