251
|
Harris TL, Worthington RJ, Hittle LE, Zurawski DV, Ernst RK, Melander C. Small molecule downregulation of PmrAB reverses lipid A modification and breaks colistin resistance. ACS Chem Biol 2014; 9:122-7. [PMID: 24131198 DOI: 10.1021/cb400490k] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Infections caused by multi-drug resistant bacteria, particularly Gram-negative bacteria, are an ever-increasing problem. While the development of new antibiotics remains one option in the fight against bacteria that have become resistant to currently available antibiotics, an attractive alternative is the development of adjuvant therapeutics that restore the efficacy of existing antibiotics. We report a small molecule adjuvant that suppresses colistin resistance in multidrug resistant Acinetobacter baumannii and Klebsiella pneumoniae by interfering with the expression of a two-component system. The compound downregulates the pmrCAB operon and reverses phosphoethanolamine modification of lipid A responsible for colistin resistance. Furthermore, colistin-susceptible and colistin-resistant bacteria do not evolve resistance to combination treatment. This represents the first definitive example of a compound that breaks antibiotic resistance by directly modulating two-component system activity.
Collapse
Affiliation(s)
- Tyler L. Harris
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Roberta J. Worthington
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Lauren E. Hittle
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, Maryland 21201, United States
| | - Daniel V. Zurawski
- Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, United States
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, Maryland 21201, United States
| | - Christian Melander
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| |
Collapse
|
252
|
Biswas S, Brunel JM, Dubus JC, Reynaud-Gaubert M, Rolain JM. Colistin: an update on the antibiotic of the 21st century. Expert Rev Anti Infect Ther 2014; 10:917-34. [DOI: 10.1586/eri.12.78] [Citation(s) in RCA: 351] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
253
|
Tan SYY, Chua SL, Liu Y, Høiby N, Andersen LP, Givskov M, Song Z, Yang L. Comparative genomic analysis of rapid evolution of an extreme-drug-resistant Acinetobacter baumannii clone. Genome Biol Evol 2013; 5:807-18. [PMID: 23538992 PMCID: PMC3673627 DOI: 10.1093/gbe/evt047] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The emergence of extreme-drug-resistant (EDR) bacterial strains in hospital and nonhospital clinical settings is a big and growing public health threat. Understanding the antibiotic resistance mechanisms at the genomic levels can facilitate the development of next-generation agents. Here, comparative genomics has been employed to analyze the rapid evolution of an EDR Acinetobacter baumannii clone from the intensive care unit (ICU) of Rigshospitalet at Copenhagen. Two resistant A. baumannii strains, 48055 and 53264, were sequentially isolated from two individuals who had been admitted to ICU within a 1-month interval. Multilocus sequence typing indicates that these two isolates belonged to ST208. The A. baumannii 53264 strain gained colistin resistance compared with the 48055 strain and became an EDR strain. Genome sequencing indicates that A. baumannii 53264 and 48055 have almost identical genomes-61 single-nucleotide polymorphisms (SNPs) were found between them. The A. baumannii 53264 strain was assembled into 130 contigs, with a total length of 3,976,592 bp with 38.93% GC content. The A. baumannii 48055 strain was assembled into 135 contigs, with a total length of 4,049,562 bp with 39.00% GC content. Genome comparisons showed that this A. baumannii clone is classified as an International clone II strain and has 94% synteny with the A. baumannii ACICU strain. The ResFinder server identified a total of 14 antibiotic resistance genes in the A. baumannii clone. Proteomic analyses revealed that a putative porin protein was down-regulated when A. baumannii 53264 was exposed to antimicrobials, which may reduce the entry of antibiotics into the bacterial cell.
Collapse
Affiliation(s)
- Sean Yang-Yi Tan
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore
| | | | | | | | | | | | | | | |
Collapse
|
254
|
Growth retardation, reduced invasiveness, and impaired colistin-mediated cell death associated with colistin resistance development in Acinetobacter baumannii. Antimicrob Agents Chemother 2013; 58:828-32. [PMID: 24247145 DOI: 10.1128/aac.01439-13] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Two colistin-susceptible/colistin-resistant (Col(s)/Col(r)) pairs of Acinetobacter baumannii strains assigned to international clone 2, which is prevalent worldwide, were sequentially recovered from two patients after prolonged colistin administration. Compared with the respective Col(s) isolates (Ab248 and Ab299, both having a colistin MIC of 0.5 μg/ml), both Col(r) isolates (Ab249 and Ab347, with colistin MICs of 128 and 32 μg/ml, respectively) significantly overexpressed pmrCAB genes, had single-amino-acid shifts in the PmrB protein, and exhibited significantly slower growth. The Col(r) isolate Ab347, tested by proteomic analysis in comparison with its Col(s) counterpart Ab299, underexpressed the proteins CsuA/B and C from the csu operon (which is necessary for biofilm formation). This isolate also underexpressed aconitase B and different enzymes involved in the oxidative stress response (KatE catalase, superoxide dismutase, and alkyl hydroperoxide reductase), suggesting a reduced response to reactive oxygen species (ROS) and, consequently, impaired colistin-mediated cell death through hydroxyl radical production. Col(s) isolates that were indistinguishable by macrorestriction analysis from Ab299 caused six sequential bloodstream infections, and isolates indistinguishable from Ab248 caused severe soft tissue infection, while Col(r) isolates indistinguishable from Ab347 and Ab249 were mainly colonizers. In particular, a Col(s) isolate identical to Ab299 was still invading the bloodstream 90 days after the colonization of this patient by Col(r) isolates. These observations indicate considerably lower invasiveness of A. baumannii clinical isolates following the development of colistin resistance.
Collapse
|
255
|
Biological cost of different mechanisms of colistin resistance and their impact on virulence in Acinetobacter baumannii. Antimicrob Agents Chemother 2013; 58:518-26. [PMID: 24189257 DOI: 10.1128/aac.01597-13] [Citation(s) in RCA: 165] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Two mechanisms of resistance to colistin have been described in Acinetobacter baumannii. One involves complete loss of lipopolysaccharide (LPS), resulting from mutations in lpxA, lpxC, or lpxD, and the second is associated with phosphoethanolamine addition to LPS, mediated through mutations in pmrAB. In order to assess the clinical impacts of both resistance mechanisms, A. baumannii ATCC 19606 and its isogenic derivatives, AL1851 ΔlpxA, AL1852 ΔlpxD, AL1842 ΔlpxC, and ATCC 19606 pmrB, were analyzed for in vitro growth rate, in vitro and in vivo competitive growth, infection of A549 respiratory alveolar epithelial cells, virulence in the Caenorhabditis elegans model, and virulence in a systemic mouse infection model. The in vitro growth rate of the lpx mutants was clearly diminished; furthermore, in vitro and in vivo competitive-growth experiments revealed a reduction in fitness for both mutant types. Infection of A549 cells with ATCC 19606 or the pmrB mutant resulted in greater loss of viability than with lpx mutants. Finally, the lpx mutants were highly attenuated in both the C. elegans and mouse infection models, while the pmrB mutant was attenuated only in the C. elegans model. In summary, while colistin resistance in A. baumannii confers a clear selective advantage in the presence of colistin treatment, it causes a noticeable cost in terms of overall fitness and virulence, with a more striking reduction associated with LPS loss than with phosphoethanolamine addition. Therefore, we hypothesize that colistin resistance mediated by changes in pmrAB will be more likely to arise in clinical settings in patients treated with colistin.
Collapse
|
256
|
Rapid determination of colistin resistance in clinical strains of Acinetobacter baumannii by use of the micromax assay. J Clin Microbiol 2013; 51:3675-82. [PMID: 23985913 DOI: 10.1128/jcm.01787-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Colistin is an old antibiotic which has been used as a therapeutic option for carbapenem- and multidrug-resistant Gram-negative bacteria, like Acinetobacter baumannii. This pathogen produces life-threatening infections, mainly in patients admitted to intensive care units. Rapid detection of resistance to colistin may improve patient outcomes and prevent the spread of resistance. For this purpose, Micromax technology was evaluated in four isogenic A. baumannii strains with known mechanisms of resistance to colistin and in 66 isolates (50 susceptible and 16 resistant). Two parameters were determined, DNA fragmentation and cell wall damage. To assess DNA fragmentation, cells trapped in a microgel were incubated with a lysing solution to remove the cell wall, and the released nucleoids were visualized under fluorescence microscopy. Fragmented DNA was observed as spots that diffuse from the nucleoid. To assess cell wall integrity, cells were incubated with a lysis solution which removes only weakened cell walls, resulting in nucleoid release exclusively in affected cells. A dose-response relationship was demonstrated between colistin concentrations and the percentages of bacteria with DNA fragmentation and cell wall damage, antibiotic effects that were delayed and less frequent in resistant strains. Receiver operating characteristic (ROC) curves demonstrated that both DNA fragmentation and cell wall damage were excellent parameters for identifying resistant strains. Obtaining ≤11% of bacteria with cell wall damage after incubation with 0.5 μg/ml colistin identified resistant strains of A. baumannii with 100% sensitivity and 96% specificity. Results were obtained in 3 h 30 min. This is a simple, rapid, and accurate assay for detecting colistin resistance in A. baumannii, with strong potential value in critical clinical situations.
Collapse
|
257
|
Joshi SG, Litake GM. Acinetobacter baumannii: An emerging pathogenic threat to public health. World J Clin Infect Dis 2013; 3:25-36. [DOI: 10.5495/wjcid.v3.i3.25] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 08/06/2013] [Indexed: 02/06/2023] Open
Abstract
Over the last three decades, Acinetobacter has gained importance as a leading nosocomial pathogen, partly due to its impressive genetic capabilities to acquire resistance and partly due to high selective pressure, especially in critical care units. This low-virulence organism has turned into a multidrug resistant pathogen and now alarming healthcare providers worldwide. Acinetobacter baumannii (A. baumannii) is a major species, contributing about 80% of all Acinetobacter hospital-acquired infections. It disseminates antibiotic resistance by virtue of its extraordinary ability to accept or donate resistance plasmids. The procedures for breaking the route of transmission are still proper hand washing and personal hygiene (both the patient and the healthcare professional), reducing patient’s biofilm burden from skin, and judicious use of antimicrobial agents. The increasing incidence of extended-spectrum beta-lactamases and carbapenemases in A. baumannii leaves almost no cure for these “bad bugs”. To control hospital outbreaks of multidrug resistant-Acinetobacter infection, we need to contain their dissemination or require new drugs or a rational combination therapy. The optimal treatment for multidrug-resistant A. baumannii infection has not been clearly established, and empirical therapy continues to require knowledge of susceptibility patterns of isolates from one’s own institution. This review mainly focused on general features and introduction to A. baumannii and its epidemiological status, potential sources of infection, risk factors, and strategies to control infection to minimize spread.
Collapse
|
258
|
Unique structural modifications are present in the lipopolysaccharide from colistin-resistant strains of Acinetobacter baumannii. Antimicrob Agents Chemother 2013; 57:4831-40. [PMID: 23877686 DOI: 10.1128/aac.00865-13] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Acinetobacter baumannii is a nosocomial opportunistic pathogen that can cause severe infections, including hospital-acquired pneumonia, wound infections, and sepsis. Multidrug-resistant (MDR) strains are prevalent, further complicating patient treatment. Due to the increase in MDR strains, the cationic antimicrobial peptide colistin has been used to treat A. baumannii infections. Colistin-resistant strains of A. baumannii with alterations to the lipid A component of lipopolysaccharide (LPS) have been reported; specifically, the lipid A structure was shown to be hepta-acylated with a phosphoethanolamine (pEtN) modification present on one of the terminal phosphate residues. Using a tandem mass spectrometry platform, we provide definitive evidence that the lipid A isolated from colistin-resistant A. baumannii MAC204 LPS contains a novel structure corresponding to a diphosphoryl hepta-acylated lipid A structure with both pEtN and galactosamine (GalN) modifications. To correlate our structural studies with clinically relevant samples, we characterized colistin-susceptible and -resistant isolates obtained from patients. These results demonstrated that the clinical colistin-resistant isolate had the same pEtN and GalN modifications as those seen in the laboratory-adapted A. baumannii strain MAC204. In summary, this work has shown complete structure characterization including the accurate assignment of acylation, phosphorylation, and glycosylation of lipid A from A. baumannii, which are important for resistance to colistin.
Collapse
|
259
|
Colistin resistance in a clinical Acinetobacter baumannii strain appearing after colistin treatment: effect on virulence and bacterial fitness. Antimicrob Agents Chemother 2013; 57:4587-9. [PMID: 23836165 DOI: 10.1128/aac.00543-13] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The fitness and virulence costs associated with the clinical acquisition of colistin resistance by Acinetobacter baumannii were evaluated. The growth of strain CR17 (colistin resistant) was less than that of strain CS01 (colistin susceptible) when the strains were grown in competition (72-h competition index, 0.008). In a murine sepsis model, CS01 and CR17 reached spleen concentrations when coinfecting of 9.31 and 6.97 log10 CFU/g, respectively, with an in vivo competition index of 0.016. Moreover, CS01 was more virulent than CR17 with respect to mortality and time to death.
Collapse
|
260
|
Small-molecule inhibition of bacterial two-component systems to combat antibiotic resistance and virulence. Future Med Chem 2013; 5:1265-84. [DOI: 10.4155/fmc.13.58] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Infections caused by multidrug-resistant bacteria are a considerable and increasing global problem. The development of new antibiotics is not keeping pace with the rapid evolution of resistance to almost all clinically available drugs, and novel strategies are required to fight bacterial infections. One such strategy is the control of pathogenic behaviors, as opposed to simply killing bacteria. Bacterial two-component system (TCS) signal transduction pathways control many pathogenic bacterial behaviors, such as virulence, biofilm formation and antibiotic resistance and are, therefore, an attractive target for the development of new drugs. This review presents an overview of TCS that are potential targets for such a strategy, describes small-molecules inhibitors of TCS identified to date and discusses assays for the identification of novel inhibitors. The future perspective for the identification and use of inhibitors of TCS to potentially provide new therapeutic options for the treatment of drug-resistant bacterial infections is discussed.
Collapse
|
261
|
Wanty C, Anandan A, Piek S, Walshe J, Ganguly J, Carlson RW, Stubbs KA, Kahler CM, Vrielink A. The structure of the neisserial lipooligosaccharide phosphoethanolamine transferase A (LptA) required for resistance to polymyxin. J Mol Biol 2013; 425:3389-402. [PMID: 23810904 DOI: 10.1016/j.jmb.2013.06.029] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 06/18/2013] [Accepted: 06/19/2013] [Indexed: 10/26/2022]
Abstract
Gram-negative bacteria possess an outer membrane envelope consisting of an outer leaflet of lipopolysaccharides, also called endotoxins, which protect the pathogen from antimicrobial peptides and have multifaceted roles in virulence. Lipopolysaccharide consists of a glycan moiety attached to lipid A, embedded in the outer membrane. Modification of the lipid A headgroups by phosphoethanolamine (PEA) or 4-amino-arabinose residues increases resistance to the cationic cyclic polypeptide antibiotic, polymyxin. Lipid A PEA transferases are members of the YhjW/YjdB/YijP superfamily and usually consist of a transmembrane domain anchoring the enzyme to the periplasmic face of the cytoplasmic membrane attached to a soluble catalytic domain. The crystal structure of the soluble domain of the protein of the lipid A PEA transferase from Neisseria meningitidis has been determined crystallographically and refined to 1.4Å resolution. The structure reveals a core hydrolase fold similar to that of alkaline phosphatase. Loop regions in the structure differ, presumably to enable interaction with the membrane-localized substrates and to provide substrate specificity. A phosphorylated form of the putative nucleophile, Thr280, is observed. Metal ions present in the active site are coordinated to Thr280 and to residues conserved among the family of transferases. The structure reveals the protein components needed for the transferase chemistry; however, substrate-binding regions are not evident and are likely to reside in the transmembrane domain of the protein.
Collapse
Affiliation(s)
- Christopher Wanty
- School of Chemistry and Biochemistry, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | | | | | | | | | | | | | | | | |
Collapse
|
262
|
Lesho E, Yoon EJ, McGann P, Snesrud E, Kwak Y, Milillo M, Onmus-Leone F, Preston L, St Clair K, Nikolich M, Viscount H, Wortmann G, Zapor M, Grillot-Courvalin C, Courvalin P, Clifford R, Waterman PE. Emergence of colistin-resistance in extremely drug-resistant Acinetobacter baumannii containing a novel pmrCAB operon during colistin therapy of wound infections. J Infect Dis 2013; 208:1142-51. [PMID: 23812239 DOI: 10.1093/infdis/jit293] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Colistin resistance is of concern since it is increasingly needed to treat infections caused by bacteria resistant to all other antibiotics and has been associated with poorer outcomes. Longitudinal data from in vivo series are sparse. METHODS Under a quality-improvement directive to intensify infection-control measures, extremely drug-resistant (XDR) bacteria undergo phenotypic and molecular analysis. RESULTS Twenty-eight XDR Acinetobacter baumannii isolates were longitudinally recovered during colistin therapy. Fourteen were susceptible to colistin, and 14 were resistant to colistin. Acquisition of colistin resistance did not alter resistance to other antibiotics. Isolates had low minimum inhibitory concentrations of an investigational aminoglycoside, belonged to multi-locus sequence type 94, were indistinguishable by pulsed-field gel electrophoresis and optical mapping, and harbored a novel pmrC1A1B allele. Colistin resistance was associated with point mutations in the pmrA1 and/or pmrB genes. Additional pmrC homologs, designated eptA-1 and eptA-2, were at distant locations from the operon. Compared with colistin-susceptible isolates, colistin-resistant isolates displayed significantly enhanced expression of pmrC1A1B, eptA-1, and eptA-2; lower growth rates; and lowered fitness. Phylogenetic analysis suggested that colistin resistance emerged from a single progenitor colistin-susceptible isolate. CONCLUSIONS We provide insights into the in vivo evolution of colistin resistance in a series of XDR A. baumannii isolates recovered during therapy of infections and emphasize the importance of antibiotic stewardship and surveillance.
Collapse
Affiliation(s)
- Emil Lesho
- Multidrug-Resistant Organism Repository and Surveillance Network, Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
263
|
Magee TV, Brown MF, Starr JT, Ackley DC, Abramite JA, Aubrecht J, Butler A, Crandon JL, Dib-Hajj F, Flanagan ME, Granskog K, Hardink JR, Huband MD, Irvine R, Kuhn M, Leach KL, Li B, Lin J, Luke DR, MacVane SH, Miller AA, McCurdy S, McKim JM, Nicolau DP, Nguyen TT, Noe MC, O’Donnell JP, Seibel SB, Shen Y, Stepan AF, Tomaras AP, Wilga PC, Zhang L, Xu J, Chen JM. Discovery of Dap-3 Polymyxin Analogues for the Treatment of Multidrug-Resistant Gram-Negative Nosocomial Infections. J Med Chem 2013; 56:5079-93. [DOI: 10.1021/jm400416u] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Thomas V. Magee
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Matthew F. Brown
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Jeremy T. Starr
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - David C. Ackley
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Joseph A. Abramite
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Jiri Aubrecht
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Andrew Butler
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Jared L. Crandon
- Center
for Anti-Infective Research
and Development, Hartford Hospital, Hartford,
Connecticut 06102, United States
| | - Fadia Dib-Hajj
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Mark E. Flanagan
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Karl Granskog
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Joel R. Hardink
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Michael D. Huband
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Rebecca Irvine
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Michael Kuhn
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Karen L. Leach
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Bryan Li
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Jian Lin
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - David R. Luke
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Shawn H. MacVane
- Center
for Anti-Infective Research
and Development, Hartford Hospital, Hartford,
Connecticut 06102, United States
| | - Alita A. Miller
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Sandra McCurdy
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | | | - David P. Nicolau
- Center
for Anti-Infective Research
and Development, Hartford Hospital, Hartford,
Connecticut 06102, United States
| | - Thuy-Trinh Nguyen
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Mark C. Noe
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - John P. O’Donnell
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Scott B. Seibel
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Yue Shen
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Antonia F. Stepan
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Andrew P. Tomaras
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| | - Paul C. Wilga
- CeeTox, Inc., Kalamazoo, Michigan 49008,
United States
| | - Li Zhang
- WuXi AppTech Co., Ltd., Shanghai, P.R. China
| | | | - Jinshan Michael Chen
- Pfizer Worldwide Research & Development, Pfizer, Inc., Groton, Connecticut 06340, United States
| |
Collapse
|
264
|
Matrix-assisted laser desorption ionization-time of flight (maldi-tof) mass spectrometry for detection of antibiotic resistance mechanisms: from research to routine diagnosis. Clin Microbiol Rev 2013; 26:103-14. [PMID: 23297261 DOI: 10.1128/cmr.00058-12] [Citation(s) in RCA: 213] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been successfully applied as an identification procedure in clinical microbiology and has been widely used in routine laboratory practice because of its economical and diagnostic benefits. The range of applications of MALDI-TOF MS has been growing constantly, from rapid species identification to labor-intensive proteomic studies of bacterial physiology. The purpose of this review is to summarize the contribution of the studies already performed with MALDI-TOF MS concerning antibiotic resistance and to analyze future perspectives in this field. We believe that current research should continue in four main directions, including the detection of antibiotic modifications by degrading enzymes, the detection of resistance mechanism determinants through proteomic studies of multiresistant bacteria, and the analysis of modifications of target sites, such as ribosomal methylation. The quantification of antibiotics is suggested as a new approach to study influx and efflux in bacterial cells. The results of the presented studies demonstrate that MALDI-TOF MS is a relevant tool for the detection of antibiotic resistance and opens new avenues for both clinical and experimental microbiology.
Collapse
|
265
|
Snitkin ES, Zelazny AM, Gupta J, Palmore TN, Murray PR, Segre JA. Genomic insights into the fate of colistin resistance and Acinetobacter baumannii during patient treatment. Genome Res 2013; 23:1155-62. [PMID: 23564252 PMCID: PMC3698508 DOI: 10.1101/gr.154328.112] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Bacterial whole-genome sequencing (WGS) of human pathogens has provided unprecedented insights into the evolution of antibiotic resistance. Most studies have focused on identification of resistance mutations, leaving one to speculate on the fate of these mutants once the antibiotic selective pressure is removed. We performed WGS on longitudinal isolates of Acinetobacter baumannii from patients undergoing colistin treatment, and upon subsequent drug withdrawal. In each of the four patients, colistin resistance evolved via mutations at the pmr locus. Upon colistin withdrawal, an ancestral susceptible strain outcompeted resistant isolates in three of the four cases. In the final case, resistance was also lost, but by a compensatory inactivating mutation in the transcriptional regulator of the pmr locus. Notably, this inactivating mutation reduced the probability of reacquiring colistin resistance when subsequently challenged in vitro. On face value, these results supported an in vivo fitness cost preventing the evolution of stable colistin resistance. However, more careful analysis of WGS data identified genomic evidence for stable colistin resistance undetected by clinical microbiological assays. Transcriptional studies validated this genomic hypothesis, showing increased pmr expression of the initial isolate. Moreover, altering the environmental growth conditions of the clinical assay recapitulated the classification as colistin resistant. Additional targeted sequencing revealed that this isolate evolved undetected in a patient undergoing colistin treatment, and was then transmitted to other hospitalized patients, further demonstrating its stability in the absence of colistin. This study provides a unique window into mutational pathways taken in response to antibiotic pressure in vivo, and demonstrates the potential for genome sequence data to predict resistance phenotypes.
Collapse
Affiliation(s)
- Evan S Snitkin
- Epithelial Biology Section, GMBB, NHGRI, Bethesda, Maryland 20892, USA
| | | | | | | | | | | | | |
Collapse
|
266
|
Beceiro A, Tomás M, Bou G. Antimicrobial resistance and virulence: a successful or deleterious association in the bacterial world? Clin Microbiol Rev 2013; 26:185-230. [PMID: 23554414 PMCID: PMC3623377 DOI: 10.1128/cmr.00059-12] [Citation(s) in RCA: 616] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Hosts and bacteria have coevolved over millions of years, during which pathogenic bacteria have modified their virulence mechanisms to adapt to host defense systems. Although the spread of pathogens has been hindered by the discovery and widespread use of antimicrobial agents, antimicrobial resistance has increased globally. The emergence of resistant bacteria has accelerated in recent years, mainly as a result of increased selective pressure. However, although antimicrobial resistance and bacterial virulence have developed on different timescales, they share some common characteristics. This review considers how bacterial virulence and fitness are affected by antibiotic resistance and also how the relationship between virulence and resistance is affected by different genetic mechanisms (e.g., coselection and compensatory mutations) and by the most prevalent global responses. The interplay between these factors and the associated biological costs depend on four main factors: the bacterial species involved, virulence and resistance mechanisms, the ecological niche, and the host. The development of new strategies involving new antimicrobials or nonantimicrobial compounds and of novel diagnostic methods that focus on high-risk clones and rapid tests to detect virulence markers may help to resolve the increasing problem of the association between virulence and resistance, which is becoming more beneficial for pathogenic bacteria.
Collapse
|
267
|
Farrugia DN, Elbourne LDH, Hassan KA, Eijkelkamp BA, Tetu SG, Brown MH, Shah BS, Peleg AY, Mabbutt BC, Paulsen IT. The complete genome and phenome of a community-acquired Acinetobacter baumannii. PLoS One 2013; 8:e58628. [PMID: 23527001 PMCID: PMC3602452 DOI: 10.1371/journal.pone.0058628] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 02/05/2013] [Indexed: 01/19/2023] Open
Abstract
Many sequenced strains of Acinetobacter baumannii are established nosocomial pathogens capable of resistance to multiple antimicrobials. Community-acquired A. baumannii in contrast, comprise a minor proportion of all A. baumannii infections and are highly susceptible to antimicrobial treatment. However, these infections also present acute clinical manifestations associated with high reported rates of mortality. We report the complete 3.70 Mbp genome of A. baumannii D1279779, previously isolated from the bacteraemic infection of an Indigenous Australian; this strain represents the first community-acquired A. baumannii to be sequenced. Comparative analysis of currently published A. baumannii genomes identified twenty-four accessory gene clusters present in D1279779. These accessory elements were predicted to encode a range of functions including polysaccharide biosynthesis, type I DNA restriction-modification, and the metabolism of novel carbonaceous and nitrogenous compounds. Conversely, twenty genomic regions present in previously sequenced A. baumannii strains were absent in D1279779, including gene clusters involved in the catabolism of 4-hydroxybenzoate and glucarate, and the A. baumannii antibiotic resistance island, known to bestow resistance to multiple antimicrobials in nosocomial strains. Phenomic analysis utilising the Biolog Phenotype Microarray system indicated that A. baumannii D1279779 can utilise a broader range of carbon and nitrogen sources than international clone I and clone II nosocomial isolates. However, D1279779 was more sensitive to antimicrobial compounds, particularly beta-lactams, tetracyclines and sulphonamides. The combined genomic and phenomic analyses have provided insight into the features distinguishing A. baumannii isolated from community-acquired and nosocomial infections.
Collapse
Affiliation(s)
- Daniel N. Farrugia
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Liam D. H. Elbourne
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Karl A. Hassan
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Bart A. Eijkelkamp
- School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia
| | - Sasha G. Tetu
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Melissa H. Brown
- School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia
| | - Bhumika S. Shah
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Anton Y. Peleg
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
- Department of Infectious Diseases, The Alfred Hospital, Melbourne, Victoria, Australia
| | - Bridget C. Mabbutt
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Ian T. Paulsen
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
- * E-mail:
| |
Collapse
|
268
|
Activities of vancomycin-containing regimens against colistin-resistant Acinetobacter baumannii clinical strains. Antimicrob Agents Chemother 2013; 57:2103-8. [PMID: 23422916 DOI: 10.1128/aac.02501-12] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Treatment of infections due to extensively drug-resistant (XDR) Acinetobacter baumannii often involves the use of antimicrobial agents in combination. Various combinations of agents have been proposed, with colistin serving as the backbone in many of them. Recent data suggest that glycopeptides, in particular vancomycin, may have unique activity against laboratory-adapted and clinical strains of A. baumannii, alone and in combination with colistin. The aim of the present study was to test this approach against three unique colistin-resistant A. baumannii clinical strains using combinations of vancomycin (VAN), colistin (COL), and doripenem (DOR). All three strains possessed the signature phosphoethanolamine modification of the lipid A moiety associated with colistin resistance and unique amino acid changes in the PmrAB two-component signal transduction system not observed in colistin-susceptible strains. In checkerboard assays, synergy (defined as a fractional inhibitory concentration index [FICI] of ≤ 0.5) was observed between COL and VAN for all three strains tested and between COL and DOR in two strains. In time-kill assays, the combinations of COL-DOR, COL-VAN, and COL-DOR-VAN resulted in complete killing of colistin-resistant A. baumannii in 1, 2, and all 3 strains, respectively. In the Galleria mellonella moth model of infection, the combinations of DOR-VAN and COL-DOR-VAN led to significantly increased survival of the larvae, compared with other combinations and monotherapy. These findings suggest that regimens containing vancomycin may confer therapeutic benefit for infection due to colistin-resistant A. baumannii.
Collapse
|
269
|
Lima TB, Pinto MFS, Ribeiro SM, de Lima LA, Viana JC, Gomes Júnior N, Cândido EDS, Dias SC, Franco OL. Bacterial resistance mechanism: what proteomics can elucidate. FASEB J 2013; 27:1291-303. [PMID: 23349550 DOI: 10.1096/fj.12-221127] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Antibiotics are important therapeutic agents commonly used for the control of bacterial infectious diseases; however, resistance to antibiotics has become a global public health problem. Therefore, effective therapy in the treatment of resistant bacteria is necessary and, to achieve this, a detailed understanding of mechanisms that underlie drug resistance must be sought. To fill the multiple gaps that remain in understanding bacterial resistance, proteomic tools have been used to study bacterial physiology in response to antibiotic stress. In general, the global analysis of changes in the protein composition of bacterial cells in response to treatment with antibiotic agents has made it possible to construct a database of proteins involved in the process of resistance to drugs with similar mechanisms of action. In the past few years, progress in using proteomic tools has provided the most realistic picture of the infective process, since these tools detect the end products of gene biosynthetic pathways, which may eventually determine a biological phenotype. In most bacterial species, alterations occur in energy and nitrogen metabolism regulation; glucan biosynthesis is up-regulated; amino acid, protein, and nucleotide synthesis is affected; and various proteins show a stress response after exposing these microorganisms to antibiotics. These issues have been useful in identifying targets for the development of novel antibiotics and also in understanding, at the molecular level, how bacteria resist antibiotics.
Collapse
Affiliation(s)
- Thais Bergamin Lima
- Centro de Análises Proteômicas e Bioquímicas, Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasilia, Brazil
| | | | | | | | | | | | | | | | | |
Collapse
|
270
|
Worthington RJ, Melander C. Combination approaches to combat multidrug-resistant bacteria. Trends Biotechnol 2013; 31:177-84. [PMID: 23333434 DOI: 10.1016/j.tibtech.2012.12.006] [Citation(s) in RCA: 399] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 12/17/2012] [Accepted: 12/19/2012] [Indexed: 12/19/2022]
Abstract
The increasing prevalence of infections caused by multidrug-resistant bacteria is a global health problem that has been exacerbated by the dearth of novel classes of antibiotics entering the clinic over the past 40 years. Herein, we describe recent developments toward combination therapies for the treatment of multidrug-resistant bacterial infections. These efforts include antibiotic-antibiotic combinations, and the development of adjuvants that either directly target resistance mechanisms such as the inhibition of β-lactamase enzymes, or indirectly target resistance by interfering with bacterial signaling pathways such as two-component systems (TCSs). We also discuss screening of libraries of previously approved drugs to identify nonobvious antimicrobial adjuvants.
Collapse
|
271
|
Hornsey M, Phee L, Longshaw C, Wareham DW. In vivo efficacy of telavancin/colistin combination therapy in a Galleria mellonella model of Acinetobacter baumannii infection. Int J Antimicrob Agents 2013; 41:285-7. [PMID: 23312607 DOI: 10.1016/j.ijantimicag.2012.11.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 11/27/2012] [Accepted: 11/28/2012] [Indexed: 02/06/2023]
Abstract
Treatment of Acinetobacter baumannii infections is challenging owing to widespread multidrug resistance and the lack of novel agents. There is now considerable interest in the potential of unorthodox combination therapies such as colistin and glycopeptides (e.g. vancomycin and teicoplanin), since potent synergy can be demonstrated in vitro. A simple invertebrate model (Galleria mellonella) has been developed to assess the in vivo activity of antimicrobial therapies and was used to investigate the efficacy of colistin combined with the lipoglycopeptide telavancin in the treatment of A. baumannii infection. Galleria mellonella larvae were inoculated with 10⁵ CFU/larvae of A. baumannii type strain ATCC 19606 or the multidrug-resistant clinical isolate AB210. Infected caterpillars were treated with either telavancin (10 mg/kg), colistin (2.5 mg/kg) or a telavancin/colistin combination. Larvae were incubated at 37 °C for up to 96 h and were scored daily. Survival curves were plotted and analysed using the log-rank test. The telavancin/colistin combination was effective in the treatment of larvae infected with both strains but was superior to colistin monotherapy in the treatment of A. baumannii AB210 (P<0.001). The combination of telavancin and colistin was effective in a simple invertebrate model of A. baumannii infection. This is in agreement with a previous in vitro study and provides preliminary in vivo evidence that such a combination might be useful therapeutically.
Collapse
Affiliation(s)
- Michael Hornsey
- Antimicrobial Research Group, Centre for Immunology and Infectious Disease, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, 4 Newark Street, London E1 2AT, UK
| | | | | | | |
Collapse
|
272
|
Braga PAC, Tata A, Gonçalves dos Santos V, Barreiro JR, Schwab NV, Veiga dos Santos M, Eberlin MN, Ferreira CR. Bacterial identification: from the agar plate to the mass spectrometer. RSC Adv 2013. [DOI: 10.1039/c2ra22063f] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
273
|
genetic determinants of intrinsic colistin tolerance in Acinetobacter baumannii. Infect Immun 2012; 81:542-51. [PMID: 23230287 DOI: 10.1128/iai.00704-12] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acinetobacter baumannii is a leading cause of multidrug-resistant infections worldwide. This organism poses a particular challenge due to its ability to acquire resistance to new antibiotics through adaptation or mutation. This study was undertaken to determine the mechanisms governing the adaptability of A. baumannii to the antibiotic colistin. Screening of a transposon mutant library identified over 30 genes involved in inducible colistin resistance in A. baumannii. One of the genes identified was lpsB, which encodes a glycosyltransferase involved in lipopolysaccharide (LPS) synthesis. We demonstrate that loss of LpsB function results in increased sensitivity to both colistin and cationic antimicrobial peptides of the innate immune system. Moreover, LpsB is critical for pathogenesis in a pulmonary model of infection. Taken together, these data define bacterial processes required for intrinsic colistin tolerance in A. baumannii and underscore the importance of outer membrane structure in both antibiotic resistance and the pathogenesis of A. baumannii.
Collapse
|
274
|
Vila J, Pachón J. Therapeutic options forAcinetobacter baumanniiinfections: an update. Expert Opin Pharmacother 2012; 13:2319-36. [DOI: 10.1517/14656566.2012.729820] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
275
|
Arduino SM, Quiroga MP, Ramírez MS, Merkier AK, Errecalde L, Di Martino A, Smayevsky J, Kaufman S, Centrón D. Transposons and integrons in colistin-resistant clones of Klebsiella pneumoniae and Acinetobacter baumannii with epidemic or sporadic behaviour. J Med Microbiol 2012; 61:1417-1420. [DOI: 10.1099/jmm.0.038968-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Sonia M. Arduino
- Instituto de Educación Medica e Investigaciones Clínicas ‘Dr Norberto Quirno’ CEMIC, Buenos Aires, Argentina
| | - María Paula Quiroga
- Laboratorio de Investigaciones de los Mecanismos de Resistencia a Antibióticos, Instituto de Microbiología y Parasitología Médica, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Facultad de Medicina, Buenos Aires, Argentina
| | - María Soledad Ramírez
- Laboratorio de Investigaciones de los Mecanismos de Resistencia a Antibióticos, Instituto de Microbiología y Parasitología Médica, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Facultad de Medicina, Buenos Aires, Argentina
| | - Andrea Karina Merkier
- Laboratorio de Investigaciones de los Mecanismos de Resistencia a Antibióticos, Instituto de Microbiología y Parasitología Médica, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Facultad de Medicina, Buenos Aires, Argentina
| | - Laura Errecalde
- Sección Microbiología, Hospital Fernández, Buenos Aires, Argentina
| | - Ana Di Martino
- Laboratorio de Bacteriología, Sanatorio de la Trinidad Mitre, Ciudad Autónoma de Buenos Aires, Argentina
| | - Jorgelina Smayevsky
- Instituto de Educación Medica e Investigaciones Clínicas ‘Dr Norberto Quirno’ CEMIC, Buenos Aires, Argentina
| | - Sara Kaufman
- Sección Microbiología, Hospital Fernández, Buenos Aires, Argentina
| | - Daniela Centrón
- Laboratorio de Investigaciones de los Mecanismos de Resistencia a Antibióticos, Instituto de Microbiología y Parasitología Médica, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Tecnológicas (IMPaM, UBA-CONICET), Facultad de Medicina, Buenos Aires, Argentina
| |
Collapse
|
276
|
Bergen PJ, Landersdorfer CB, Zhang J, Zhao M, Lee HJ, Nation RL, Li J. Pharmacokinetics and pharmacodynamics of 'old' polymyxins: what is new? Diagn Microbiol Infect Dis 2012; 74:213-23. [PMID: 22959816 DOI: 10.1016/j.diagmicrobio.2012.07.010] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 07/12/2012] [Accepted: 07/23/2012] [Indexed: 12/21/2022]
Abstract
'Old' colistin and polymyxin B are increasingly used as last-line therapy against multidrug-resistant Gram-negative bacteria Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae. For intravenous administration, colistin is dosed as its inactive prodrug colistin methanesulfonate (sodium), while polymyxin B is used as its sulfate (active antibacterial). Over the last decade, significant progress has been made in understanding their chemistry, pharmacokinetics (PK), and pharmacodynamics (PD). The first scientifically based dosing suggestions are now available for colistin methanesulfonate to generate a desired target steady-state plasma concentration of formed colistin in various categories of critically ill patients. As simply increasing polymyxin dosage regimens is not an option for optimizing their PK/PD due to nephrotoxicity, combination therapy with other antibiotics has great potential to maximize the efficacy of polymyxins while minimizing emergence of resistance. We must pursue rational approaches to the use of polymyxins and other existing antibiotics through the application of PK/PD principles.
Collapse
Affiliation(s)
- Phillip J Bergen
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | | | | | | | | | | | | |
Collapse
|
277
|
Rapid killing of Acinetobacter baumannii by polymyxins is mediated by a hydroxyl radical death pathway. Antimicrob Agents Chemother 2012; 56:5642-9. [PMID: 22908157 DOI: 10.1128/aac.00756-12] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Acinetobacter baumannii is an opportunistic pathogen that is a cause of clinically significant nosocomial infections. Increasingly, clinical isolates of A. baumannii are extensively resistant to numerous antibiotics, and the use of polymyxin antibiotics against these infections is often the final treatment option. Historically, the polymyxins have been thought to kill bacteria through membrane lysis. Here, we present an alternative mechanism based on data demonstrating that polymyxins induce rapid cell death through hydroxyl radical production. Supporting this notion, we found that inhibition of radical production delays the ability of polymyxins to kill A. baumannii. Notably, we demonstrate that this mechanism of killing occurs in multidrug-resistant clinical isolates of A. baumannii and that this response is not induced in a polymyxin-resistant isolate. This study is the first to demonstrate that polymyxins induce rapid killing of A. baumannii and other Gram-negatives through hydroxyl radical production. This significantly augments our understanding of the mechanism of polymyxin action, which is critical knowledge toward the development of adjunctive therapies, particularly given the increasing necessity for treatment with these antibiotics in the clinical setting.
Collapse
|
278
|
Livermore DM. Current epidemiology and growing resistance of gram-negative pathogens. Korean J Intern Med 2012; 27:128-42. [PMID: 22707882 PMCID: PMC3372794 DOI: 10.3904/kjim.2012.27.2.128] [Citation(s) in RCA: 233] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 04/09/2012] [Indexed: 12/24/2022] Open
Abstract
In the 1980s, gram-negative pathogens appeared to have been beaten by oxyimino-cephalosporins, carbapenems, and fluoroquinolones. Yet these pathogens have fought back, aided by their membrane organization, which promotes the exclusion and efflux of antibiotics, and by a remarkable propensity to recruit, transfer, and modify the expression of resistance genes, including those for extended-spectrum β-lactamases (ESBLs), carbapenemases, aminoglycoside-blocking 16S rRNA methylases, and even a quinolone-modifying variant of an aminoglycoside-modifying enzyme. Gram-negative isolates--both fermenters and non-fermenters--susceptible only to colistin and, more variably, fosfomycin and tigecycline, are encountered with increasing frequency, including in Korea. Some ESBLs and carbapenemases have become associated with strains that have great epidemic potential, spreading across countries and continents; examples include Escherichia coli sequence type (ST)131 with CTX-M-15 ESBL and Klebsiella pneumoniae ST258 with KPC carbapenemases. Both of these high-risk lineages have reached Korea. In other cases, notably New Delhi Metallo carbapenemase, the relevant gene is carried by promiscuous plasmids that readily transfer among strains and species. Unless antibiotic stewardship is reinforced, microbiological diagnosis accelerated, and antibiotic development reinvigorated, there is a real prospect that the antibiotic revolution of the 20th century will crumble.
Collapse
|
279
|
Roca I, Espinal P, Vila-Farrés X, Vila J. The Acinetobacter baumannii Oxymoron: Commensal Hospital Dweller Turned Pan-Drug-Resistant Menace. Front Microbiol 2012; 3:148. [PMID: 22536199 PMCID: PMC3333477 DOI: 10.3389/fmicb.2012.00148] [Citation(s) in RCA: 246] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 03/28/2012] [Indexed: 12/28/2022] Open
Abstract
During the past few decades Acinetobacter baumannii has evolved from being a commensal dweller of health-care facilities to constitute one of the most annoying pathogens responsible for hospitalary outbreaks and it is currently considered one of the most important nosocomial pathogens. In a prevalence study of infections in intensive care units conducted among 75 countries of the five continents, this microorganism was found to be the fifth most common pathogen. Two main features contribute to the success of A. baumannii: (i) A. baumannii exhibits an outstanding ability to accumulate a great variety of resistance mechanisms acquired by different mechanisms, either mutations or acquisition of genetic elements such as plasmids, integrons, transposons, or resistant islands, making this microorganism multi- or pan-drug-resistant and (ii) The ability to survive in the environment during prolonged periods of time which, combined with its innate resistance to desiccation and disinfectants, makes A. baumannii almost impossible to eradicate from the clinical setting. In addition, its ability to produce biofilm greatly contributes to both persistence and resistance. In this review, the pathogenesis of the infections caused by this microorganism as well as the molecular bases of antibacterial resistance and clinical aspects such as treatment and potential future therapeutic strategies are discussed in depth.
Collapse
Affiliation(s)
- Ignasi Roca
- Department of Clinical Microbiology, School of Medicine, IDIBAPS and Barcelona Centre for International Health Research, Hospital Clínic-Universitat de Barcelona Barcelona, Spain
| | | | | | | |
Collapse
|
280
|
In vitro activity of telavancin in combination with colistin versus Gram-negative bacterial pathogens. Antimicrob Agents Chemother 2012; 56:3080-5. [PMID: 22491686 DOI: 10.1128/aac.05870-11] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The treatment of Gram-negative infections is increasingly compromised by the spread of resistance. With few agents currently in development, clinicians are now considering the use of unorthodox combination therapies for multidrug-resistant strains. Here we assessed the in vitro activity of the novel lipoglycopeptide telavancin (TLV) when combined with colistin (COL) versus 13 Gram-negative type strains and 66 clinical isolates. Marked synergy was observed in either checkerboard (fractional inhibitory concentration index [FICI], <0.5; susceptibility breakpoint index [SBPI], >2) or time-kill assays (>2-log reduction in viable counts compared with starting inocula at 24 h) versus the majority of COL-susceptible enterobacteria, Stenotrophomonas maltophilia, and Acinetobacter baumannii isolates, but only limited effects were seen against Pseudomonas aeruginosa or strains with COL resistance. Using an Etest/agar dilution method, the activity of TLV was potentiated by relatively low concentrations of COL (0.25 to 0.75 μg/ml), reducing the MIC of TLV from >32 μg/ml to ≤ 1 μg/ml for 35% of the clinical isolates. This provides further evidence that glycopeptide-polymyxin combinations may be a useful therapeutic option in the treatment of Gram-negative infections.
Collapse
|
281
|
Current world literature. Curr Opin Lipidol 2012; 23:156-63. [PMID: 22418573 DOI: 10.1097/mol.0b013e3283521229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
282
|
Cai Y, Chai D, Wang R, Liang B, Bai N. Colistin resistance of Acinetobacter baumannii: clinical reports, mechanisms and antimicrobial strategies. J Antimicrob Chemother 2012; 67:1607-15. [PMID: 22441575 DOI: 10.1093/jac/dks084] [Citation(s) in RCA: 386] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Colistin is the last resort for treatment of multidrug-resistant Acinetobacter baumannii. Unfortunately, resistance to colistin has been reported all over the world. The highest resistance rate was reported in Asia, followed by Europe. The heteroresistance rate of A. baumannii to colistin is generally higher than the resistance rate. The mechanism of resistance might be loss of lipopolysaccharide or/and the PmrAB two-component system. Pharmacokinetic/pharmacodynamic studies revealed that colistin monotherapy is unable to prevent resistance, and combination therapy might be the best antimicrobial strategy against colistin-resistant A. baumannii. Colistin/rifampicin and colistin/carbapenem are the most studied combinations that showed promising results in vitro, in vivo and in the clinic. New peptides showing good activity against colistin-resistant A. baumannii are also being investigated.
Collapse
Affiliation(s)
- Yun Cai
- Department of Clinical Pharmacology, PLA General Hospital, Beijing 100853, People's Republic of China
| | | | | | | | | |
Collapse
|
283
|
Beceiro A, Tomás M, Bou G. [Antimicrobial resistance and virulence: a beneficial relationship for the microbial world?]. Enferm Infecc Microbiol Clin 2012; 30:492-9. [PMID: 22385639 DOI: 10.1016/j.eimc.2012.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 01/01/2012] [Indexed: 11/28/2022]
Abstract
While bacterial virulence has experienced a long host/pathogen-dependent evolutionary process, antimicrobial resistance has had a very different, shorting and changing evolution due to the biological pressure caused by the introduction of the antimicrobials in human medicine. This strong pressure has forced the microorganisms to adapt to these changing conditions, continuously acquiring or developing new resistance mechanisms, causing major changes in cellular functions and finally influencing the virulence and bacterial fitness. Multiple factors may mediate in the relationship between virulence and resistance. The genes often involved in both phenomena have the same transport and dispersion mediums. Islands, integrons, transposons and other genetic elements could also facilitate the combined selection of virulence and resistance genes. The increase in resistance can affect virulence in different ways, mainly depending on the bacterial species, the environment, and the mechanism of resistance. This review presents the different phenomena in which the genetic mechanism that provides an advantage over the antimicrobials directly affects the virulence and fitness, such as changes in the structure of the cellular wall, efflux pumps, porins or two-component regulatory systems. The co-selection of virulence and antimicrobial resistance factors and the relative ease of bacteria to develop compensatory mutations can favour, particularly in environments with high antibiotic pressure, the emergence of prevalent clones. These can be virulent and with few treatment options, and could be a major health problem in the near future.
Collapse
Affiliation(s)
- Alejandro Beceiro
- Servizo de Microbioloxía-INIBIC, Complexo Hospitalario Universitario A Coruña, A Coruña, España.
| | | | | |
Collapse
|
284
|
Deciphering the magainin resistance process of Escherichia coli strains in light of the cytosolic proteome. Antimicrob Agents Chemother 2012; 56:1714-24. [PMID: 22290970 DOI: 10.1128/aac.05558-11] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Antimicrobial peptides (AMPs) are effective antibiotic agents commonly found in plants, animals, and microorganisms, and they have been suggested as the future of antimicrobial chemotherapies. It is vital to understand the molecular details that define the mechanism of action of resistance to AMPs for a rational planning of the next antibiotic generation and also to shed some light on the complex AMP mechanism of action. Here, the antibiotic resistance of Escherichia coli ATCC 8739 to magainin I was evaluated in the cytosolic subproteome. Magainin-resistant strains were selected after 10 subsequent spreads at subinhibitory concentrations of magainin I (37.5 mg · liter⁻¹), and their cytosolic proteomes were further compared to those of magainin-susceptible strains through two-dimensional electrophoresis analysis. As a result, 41 differentially expressed proteins were detected by in silico analysis and further identified by tandem mass spectrometry de novo sequencing. Functional categorization indicated an intense metabolic response mainly in energy and nitrogen uptake, stress response, amino acid conversion, and cell wall thickness. Indeed, data reported here show that resistance to cationic antimicrobial peptides possesses a greater molecular complexity than previously supposed, resulting in cell commitment to several metabolic pathways.
Collapse
|
285
|
López-Rojas R, Jiménez-Mejías ME, Lepe JA, Pachón J. Acinetobacter baumannii resistant to colistin alters its antibiotic resistance profile: a case report from Spain. J Infect Dis 2011; 204:1147-8. [PMID: 21881133 DOI: 10.1093/infdis/jir476] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
286
|
Colistin-resistant, lipopolysaccharide-deficient Acinetobacter baumannii responds to lipopolysaccharide loss through increased expression of genes involved in the synthesis and transport of lipoproteins, phospholipids, and poly-β-1,6-N-acetylglucosamine. Antimicrob Agents Chemother 2011; 56:59-69. [PMID: 22024825 DOI: 10.1128/aac.05191-11] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We recently demonstrated that colistin resistance in Acinetobacter baumannii can result from mutational inactivation of genes essential for lipid A biosynthesis (Moffatt JH, et al., Antimicrob. Agents Chemother. 54:4971-4977). Consequently, strains harboring these mutations are unable to produce the major Gram-negative bacterial surface component, lipopolysaccharide (LPS). To understand how A. baumannii compensates for the lack of LPS, we compared the transcriptional profile of the A. baumannii type strain ATCC 19606 to that of an isogenic, LPS-deficient, lpxA mutant strain. The analysis of the expression profiles indicated that the LPS-deficient strain showed increased expression of many genes involved in cell envelope and membrane biogenesis. In particular, upregulated genes included those involved in the Lol lipoprotein transport system and the Mla-retrograde phospholipid transport system. In addition, genes involved in the synthesis and transport of poly-β-1,6-N-acetylglucosamine (PNAG) also were upregulated, and a corresponding increase in PNAG production was observed. The LPS-deficient strain also exhibited the reduced expression of genes predicted to encode the fimbrial subunit FimA and a type VI secretion system (T6SS). The reduced expression of genes involved in T6SS correlated with the detection of the T6SS-effector protein AssC in culture supernatants of the A. baumannii wild-type strain but not in the LPS-deficient strain. Taken together, these data show that, in response to total LPS loss, A. baumannii alters the expression of critical transport and biosynthesis systems associated with modulating the composition and structure of the bacterial surface.
Collapse
|