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Pelling H, Bennett V, Bock LJ, Wand ME, Denham EL, MacFarlane WM, Sutton JM, Jones BV. Identification of mechanisms modulating chlorhexidine and octenidine susceptibility in Proteus mirabilis. J Appl Microbiol 2024; 135:lxae173. [PMID: 38991984 DOI: 10.1093/jambio/lxae173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 06/20/2024] [Accepted: 07/10/2024] [Indexed: 07/13/2024]
Abstract
AIMS We aimed to identify mechanisms underlying the tolerance of Proteus mirabilis-a common cause of catheter associated urinary tract infection-to the clinically used biocides chlorhexidine (CHD) and octenidine (OCT). METHODS AND RESULTS We adapted three clinical isolates to grow at concentrations of 512 µg ml-1 CHD and 128 µg ml-1 OCT. Genetic characterization and complementation studies revealed mutations inactivating the smvR repressor and increasing smvA efflux expression were associated with adaptation to both biocides. Mutations in mipA (encoding the MltA interacting protein) were less prevalent than smvR mutations and only identified in CHD adapted populations. Mutations in the rppA response regulator were exclusive to one adapted isolate and were linked with reduced polymyxin B susceptibility and a predicted gain of function after biocide adaptation. Biocide adaptation had no impact on crystalline biofilm formation. CONCLUSIONS SmvR inactivation is a key mechanism in both CHD and OCT tolerance. MipA inactivation alone confers moderate protection against CHD, and rppA showed no direct role in either CHD or OCT susceptibility.
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Affiliation(s)
- Harriet Pelling
- Department of Life Sciences, University of Bath, Bath BA2 7AY, United Kingdom
- School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - Vicky Bennett
- Department of Life Sciences, University of Bath, Bath BA2 7AY, United Kingdom
| | - Lucy J Bock
- United Kingdom Health Security Agency, Salisbury, United Kingdom
| | - Matthew E Wand
- United Kingdom Health Security Agency, Salisbury, United Kingdom
| | - Emma L Denham
- Department of Life Sciences, University of Bath, Bath BA2 7AY, United Kingdom
| | - Wendy M MacFarlane
- School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - J Mark Sutton
- United Kingdom Health Security Agency, Salisbury, United Kingdom
| | - Brian V Jones
- Department of Life Sciences, University of Bath, Bath BA2 7AY, United Kingdom
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2
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Clarke OE, Pelling H, Bennett V, Matsumoto T, Gregory GE, Nzakizwanayo J, Slate AJ, Preston A, Laabei M, Bock LJ, Wand ME, Ikebukuro K, Gebhard S, Sutton JM, Jones BV. Lipopolysaccharide structure modulates cationic biocide susceptibility and crystalline biofilm formation in Proteus mirabilis. Front Microbiol 2023; 14:1150625. [PMID: 37089543 PMCID: PMC10113676 DOI: 10.3389/fmicb.2023.1150625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 03/06/2023] [Indexed: 04/08/2023] Open
Abstract
Chlorhexidine (CHD) is a cationic biocide used ubiquitously in healthcare settings. Proteus mirabilis, an important pathogen of the catheterized urinary tract, and isolates of this species are often described as "resistant" to CHD-containing products used for catheter infection control. To identify the mechanisms underlying reduced CHD susceptibility in P. mirabilis, we subjected the CHD tolerant clinical isolate RS47 to random transposon mutagenesis and screened for mutants with reduced CHD minimum inhibitory concentrations (MICs). One mutant recovered from these screens (designated RS47-2) exhibited ~ 8-fold reduction in CHD MIC. Complete genome sequencing of RS47-2 showed a single mini-Tn5 insert in the waaC gene involved in lipopolysaccharide (LPS) inner core biosynthesis. Phenotypic screening of RS47-2 revealed a significant increase in cell surface hydrophobicity and serum susceptibility compared to the wildtype, and confirmed defects in LPS production congruent with waaC inactivation. Disruption of waaC was also associated with increased susceptibility to a range of other cationic biocides but did not affect susceptibility to antibiotics tested. Complementation studies showed that repression of smvA efflux activity in RS47-2 further increased susceptibility to CHD and other cationic biocides, reducing CHD MICs to values comparable with the most CHD susceptible isolates characterized. The formation of crystalline biofilms and blockage of urethral catheters was also significantly attenuated in RS47-2. Taken together, these data show that aspects of LPS structure and upregulation of the smvA efflux system function in synergy to modulate susceptibility to CHD and other cationic biocides, and that LPS structure is also an important factor in P. mirabilis crystalline biofilm formation.
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Affiliation(s)
- O. E. Clarke
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - H. Pelling
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - V. Bennett
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - T. Matsumoto
- Department of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - G. E. Gregory
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - J. Nzakizwanayo
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - A. J. Slate
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - A. Preston
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - M. Laabei
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - L. J. Bock
- United Kingdom Health Security Agency, Salisbury, United Kingdom
| | - M. E. Wand
- United Kingdom Health Security Agency, Salisbury, United Kingdom
| | - K. Ikebukuro
- Department of Biotechnology and Life Sciences, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - S. Gebhard
- Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - J. M. Sutton
- United Kingdom Health Security Agency, Salisbury, United Kingdom
| | - B. V. Jones
- Department of Life Sciences, University of Bath, Bath, United Kingdom
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In Vivo Role of Two-Component Regulatory Systems in Models of Urinary Tract Infections. Pathogens 2023; 12:pathogens12010119. [PMID: 36678467 PMCID: PMC9861413 DOI: 10.3390/pathogens12010119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/23/2022] [Accepted: 01/08/2023] [Indexed: 01/12/2023] Open
Abstract
Two-component signaling systems (TCSs) are finely regulated mechanisms by which bacteria adapt to environmental conditions by modifying the expression of target genes. In bacterial pathogenesis, TCSs play important roles in modulating adhesion to mucosal surfaces, resistance to antibiotics, and metabolic adaptation. In the context of urinary tract infections (UTI), one of the most common types infections causing significant health problems worldwide, uropathogens use TCSs for adaptation, survival, and establishment of pathogenicity. For example, uropathogens can exploit TCSs to survive inside bladder epithelial cells, sense osmolar variations in urine, promote their ascension along the urinary tract or even produce lytic enzymes resulting in exfoliation of the urothelium. Despite the usefulness of studying the function of TCSs in in vitro experimental models, it is of primary necessity to study bacterial gene regulation also in the context of host niches, each displaying its own biological, chemical, and physical features. In light of this, the aim of this review is to provide a concise description of several bacterial TCSs, whose activity has been described in mouse models of UTI.
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Gmiter D, Kaca W. Into the understanding the multicellular lifestyle of Proteus mirabilis on solid surfaces. Front Cell Infect Microbiol 2022; 12:864305. [PMID: 36118021 PMCID: PMC9478170 DOI: 10.3389/fcimb.2022.864305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 08/15/2022] [Indexed: 11/17/2022] Open
Abstract
Indwelling urinary catheterization can lead to the development of catheter-associated urinary tract infections (CAUTIs), an important type of nosocomial infection, as well as other medical issues among institutionalized adults. Recently, Proteus mirabilis was highlighted as the important cause of CAUTIs. The pathogenicity of P. mirabilis is dependent on two multicellular types of surface colonization: the adherence and swarming motility. Adhesion, mostly mediated by fimbrial and nonfimbrial adhesins, is important for the initiation of biofilm formation. Moreover, the production of urease frequently results in biofilm crystallization, which leads to the blockage of catheters. The heterologous polymeric matrix of the biofilm offers protection against antibiotics and the host immune system. P. mirabilis displays remarkable motility abilities. After contact with solid surfaces, hyper-flagellated cells are able to rapidly migrate. The importance of swarming motility in CAUTIs development remains controversial; however, it was indicated that swarming cells were able to co-express other virulence factors. Furthermore, flagella are strong immunomodulating proteins. On the other hand, both biofilm formation and swarming motility implicates multiple inter- and intraspecies interactions, which might contribute to the pathogenicity.
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5
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Miyoshi SI, Kumagai M, Tanida R, Soda K, Yoshimoto Y, Mizuno T. Inhibitory Effects of Polymyxin B and Human LL-37 on the Flagellin Expression in Vibrio vulnificus. Biocontrol Sci 2022; 27:57-64. [PMID: 35753794 DOI: 10.4265/bio.27.57] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Vibrio vulnificus, an opportunistic human pathogen responsible for primary septicemia, initiates pathogenesis by attachment to the intestinal epithelial cells for which the motility by the polar flagellum plays an essential role. The proteomic analysis of outer membrane proteins showed that the treatment with the 1/2 minimum inhibitory concentration (MIC) of polymyxin B (a bacterial antimicrobial peptide) led to the reduced production of flagellin (a major component of the polar flagellum). Furthermore, the bacterial motility was inhibited in the presence of 1/2 MIC of polymyxin B. V. vulnificus has six flagellin genes organized into the flaFBA and flaCDE loci. The flaA was found to be expressed higher than flaC, and its expression was significantly decreased by polymyxin B. As well as polymyxin B, the 1/2 MIC of LL-37 (a human intestinal antimicrobial peptide) reduced the expression of flaA. In addition, among four fragments of LL-37, KI-18 and FK-13 containing F17KRIVQRIKDELR29 could lead to the decreased expression of flaA. Because the motility closely relates to virulence of V. vulnificus, the findings obtained herein indicate that LL-37 may reduce the bacterial virulence through inhibition of the motility via the polar flagellum.
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Affiliation(s)
- Shin-Ichi Miyoshi
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
| | - Mika Kumagai
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
| | - Ryousuke Tanida
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
| | - Kohei Soda
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
| | - Yuri Yoshimoto
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
| | - Tamaki Mizuno
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
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6
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Pelling H, Bock LJ, Nzakizwanayo J, Wand ME, Denham EL, MacFarlane WM, Sutton JM, Jones BV. De-repression of the smvA efflux system arises in clinical isolates of Proteus mirabilis and reduces susceptibility to chlorhexidine and other biocides. Antimicrob Agents Chemother 2019; 63:AAC.01535-19. [PMID: 31570392 PMCID: PMC6879213 DOI: 10.1128/aac.01535-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 09/18/2019] [Indexed: 01/14/2023] Open
Abstract
Proteus mirabilis is a common pathogen of the catheterised urinary tract and often described as intrinsically resistant to the biocide chlorhexidine (CHD). Here we demonstrate that de-repression of the smvA efflux system has occurred in clinical isolates of P. mirabilis and reduces susceptibility to CHD and other cationic biocides. Compared to other isolates examined, P. mirabilis RS47 exhibited a significantly higher CHD MIC (≥512 μg/ml) and significantly greater expression of smvA. Comparison of the RS47 smvA and cognate smvR repressor with sequences from other isolates, indicated that RS47 encodes an inactivated smvR. Complementation of RS47 with a functional smvR from isolate RS50a (which exhibited the lowest smvA expression and lowest CHD MIC) reduced smvA expression by ∼59-fold, and markedly lowered the MIC of CHD and other cationic biocides. Although complementation of RS47 did not reduce MICs to concentrations observed in isolate RS50a, the significantly lower polymyxin B MIC of RS50a indicated that differences in LPS structure are also a factor in P. mirabilis CHD susceptibility. To determine if exposure to CHD can select for mutations in smvR, clinical isolates with the lowest CHD MICs were adapted to grow at increasing concentrations of CHD up to 512 μg/ml. Analysis of the smvR in adapted populations indicated that mutations predicted to inactivate smvR occurred following CHD exposure in some isolates. Collectively, our data show that smvA de-repression contributes to reduced biocide susceptibility in P. mirabilis, but differences in LPS structure between strains are also likely to be an important factor.
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Affiliation(s)
- H Pelling
- Dept. of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, BN2 4GJ, UK
| | - L J Bock
- National Infections Service, Public Health England, Porton Down, Salisbury, SP4 0JG, UK
| | - J Nzakizwanayo
- Dept. of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - M E Wand
- National Infections Service, Public Health England, Porton Down, Salisbury, SP4 0JG, UK
| | - E L Denham
- Dept. of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - W M MacFarlane
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, BN2 4GJ, UK
| | - J M Sutton
- National Infections Service, Public Health England, Porton Down, Salisbury, SP4 0JG, UK
| | - B V Jones
- Dept. of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
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Aghapour Z, Gholizadeh P, Ganbarov K, Bialvaei AZ, Mahmood SS, Tanomand A, Yousefi M, Asgharzadeh M, Yousefi B, Kafil HS. Molecular mechanisms related to colistin resistance in Enterobacteriaceae. Infect Drug Resist 2019; 12:965-975. [PMID: 31190901 PMCID: PMC6519339 DOI: 10.2147/idr.s199844] [Citation(s) in RCA: 188] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Accepted: 03/04/2019] [Indexed: 12/16/2022] Open
Abstract
Colistin is an effective antibiotic for treatment of most multidrug-resistant Gram-negative bacteria. It is used currently as a last-line drug for infections due to severe Gram-negative bacteria followed by an increase in resistance among Gram-negative bacteria. Colistin resistance is considered a serious problem, due to a lack of alternative antibiotics. Some bacteria, including Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacteriaceae members, such as Escherichia coli, Salmonella spp., and Klebsiella spp. have an acquired resistance against colistin. However, other bacteria, including Serratia spp., Proteus spp. and Burkholderia spp. are naturally resistant to this antibiotic. In addition, clinicians should be alert to the possibility of colistin resistance among multidrug-resistant bacteria and development through mutation or adaptation mechanisms. Rapidly emerging bacterial resistance has made it harder for us to rely completely on the discovery of new antibiotics; therefore, we need to have logical approaches to use old antibiotics, such as colistin. This review presents current knowledge about the different mechanisms of colistin resistance.
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Affiliation(s)
- Zahra Aghapour
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.,Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Pourya Gholizadeh
- Tuberculosis and Lung Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | | | - Suhad Saad Mahmood
- Department of Biotechnology, College of Science, University of Baghdad, Baghdad, Iraq
| | - Asghar Tanomand
- Department of Microbiology, Maragheh University of Medical Sciences, Maragheh, Iran
| | - Mehdi Yousefi
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohammad Asgharzadeh
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Bahman Yousefi
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Hossein Samadi Kafil
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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8
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MrpJ Directly Regulates Proteus mirabilis Virulence Factors, Including Fimbriae and Type VI Secretion, during Urinary Tract Infection. Infect Immun 2018; 86:IAI.00388-18. [PMID: 30082479 DOI: 10.1128/iai.00388-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 07/30/2018] [Indexed: 12/18/2022] Open
Abstract
Proteus mirabilis is a leading cause of catheter-associated urinary tract infections (CAUTIs) and urolithiasis. The transcriptional regulator MrpJ inversely modulates two critical aspects of P. mirabilis UTI progression: fimbria-mediated attachment and flagellum-mediated motility. Transcriptome data indicated a network of virulence-associated genes under MrpJ's control. Here, we identify the direct gene regulon of MrpJ and its contribution to P. mirabilis pathogenesis, leading to the discovery of novel virulence targets. Chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) was used for the first time in a CAUTI pathogen to probe for in vivo direct targets of MrpJ. Selected MrpJ-regulated genes were mutated and assessed for their contribution to UTI using a mouse model. ChIP-seq revealed a palindromic MrpJ binding sequence and 78 MrpJ-bound regions, including binding sites upstream of genes involved in motility, fimbriae, and a type VI secretion system (T6SS). A combinatorial mutation approach established the contribution of three fimbriae (fim8A, fim14A, and pmpA) to UTI and a new pathogenic role for the T6SS in UTI progression. In conclusion, this study (i) establishes the direct gene regulon and an MrpJ consensus binding site and (ii) led to the discovery of new virulence genes in P. mirabilis UTI, which could be targeted for therapeutic intervention of CAUTI.
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9
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Swarmer Cell Development of the Bacterium Proteus mirabilis Requires the Conserved Enterobacterial Common Antigen Biosynthesis Gene rffG. J Bacteriol 2018; 200:JB.00230-18. [PMID: 29967121 DOI: 10.1128/jb.00230-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 06/27/2018] [Indexed: 01/01/2023] Open
Abstract
Individual cells of the bacterium Proteus mirabilis can elongate up to 40-fold on surfaces before engaging in a cooperative surface-based motility termed swarming. How cells regulate this dramatic morphological remodeling remains an open question. In this paper, we move forward the understanding of this regulation by demonstrating that P. mirabilis requires the gene rffG for swarmer cell elongation and subsequent swarm motility. The rffG gene encodes a protein homologous to the dTDP-glucose 4,6-dehydratase protein of Escherichia coli, which contributes to enterobacterial common antigen biosynthesis. Here, we characterize the rffG gene in P. mirabilis, demonstrating that it is required for the production of large lipopolysaccharide-linked moieties necessary for wild-type cell envelope integrity. We show that the absence of the rffG gene induces several stress response pathways, including those controlled by the transcriptional regulators RpoS, CaiF, and RcsB. We further show that in rffG-deficient cells, the suppression of the Rcs phosphorelay, via loss of RcsB, is sufficient to induce cell elongation and swarm motility. However, the loss of RcsB does not rescue cell envelope integrity defects and instead results in abnormally shaped cells, including cells producing more than two poles. We conclude that an RcsB-mediated response acts to suppress the emergence of shape defects in cell envelope-compromised cells, suggesting an additional role for RcsB in maintaining cell morphology under stress conditions. We further propose that the composition of the cell envelope acts as a checkpoint before cells initiate swarmer cell elongation and motility.IMPORTANCEProteus mirabilis swarm motility has been implicated in pathogenesis. We have found that cells deploy multiple uncharacterized strategies to handle cell envelope stress beyond the Rcs phosphorelay when attempting to engage in swarm motility. While RcsB is known to directly inhibit the master transcriptional regulator for swarming, we have shown an additional role for RcsB in protecting cell morphology. These data support a growing appreciation that the Rcs phosphorelay is a multifunctional regulator of cell morphology in addition to its role in microbial stress responses. These data also strengthen the paradigm that outer membrane composition is a crucial checkpoint for modulating entry into swarm motility. Furthermore, the rffG-dependent moieties provide a novel attractive target for potential antimicrobials.
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Trimble MJ, Mlynárčik P, Kolář M, Hancock REW. Polymyxin: Alternative Mechanisms of Action and Resistance. Cold Spring Harb Perspect Med 2016; 6:cshperspect.a025288. [PMID: 27503996 DOI: 10.1101/cshperspect.a025288] [Citation(s) in RCA: 254] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Antibiotic resistance among pathogenic bacteria is an ever-increasing issue worldwide. Unfortunately, very little has been achieved in the pharmaceutical industry to combat this problem. This has led researchers and the medical field to revisit past drugs that were deemed too toxic for clinical use. In particular, the cyclic cationic peptides polymyxin B and colistin, which are specific for Gram-negative bacteria, have been used as "last resort" antimicrobials. Before the 1980s, these drugs were known for their renal and neural toxicities; however, new clinical practices and possibly improved manufacturing have made them safer to use. Previously suggested to primarily attack the membranes of Gram-negative bacteria and to not easily select for resistant mutants, recent research exploring resistance and mechanisms of action has provided new perspectives. This review focuses primarily on the proposed alternative mechanisms of action, known resistance mechanisms, and how these support the alternative mechanisms of action.
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Affiliation(s)
- Michael J Trimble
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Patrik Mlynárčik
- Department of Microbiology, Faculty of Medicine and Dentistry, Palacký University, 771 47 Olomouc, Czech Republic
| | - Milan Kolář
- Department of Microbiology, Faculty of Medicine and Dentistry, Palacký University, 771 47 Olomouc, Czech Republic
| | - Robert E W Hancock
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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11
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Abstract
Proteus mirabilis is a Gram-negative bacterium and is well known for its ability to robustly swarm across surfaces in a striking bulls'-eye pattern. Clinically, this organism is most frequently a pathogen of the urinary tract, particularly in patients undergoing long-term catheterization. This review covers P. mirabilis with a focus on urinary tract infections (UTI), including disease models, vaccine development efforts, and clinical perspectives. Flagella-mediated motility, both swimming and swarming, is a central facet of this organism. The regulation of this complex process and its contribution to virulence is discussed, along with the type VI-secretion system-dependent intra-strain competition, which occurs during swarming. P. mirabilis uses a diverse set of virulence factors to access and colonize the host urinary tract, including urease and stone formation, fimbriae and other adhesins, iron and zinc acquisition, proteases and toxins, biofilm formation, and regulation of pathogenesis. While significant advances in this field have been made, challenges remain to combatting complicated UTI and deciphering P. mirabilis pathogenesis.
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12
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Liu MC, Tsai YL, Huang YW, Chen HY, Hsueh PR, Lai SY, Chen LC, Chou YH, Lin WY, Liaw SJ. Stenotrophomonas maltophilia PhoP, a Two-Component Response Regulator, Involved in Antimicrobial Susceptibilities. PLoS One 2016; 11:e0153753. [PMID: 27159404 PMCID: PMC4861329 DOI: 10.1371/journal.pone.0153753] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 04/04/2016] [Indexed: 01/02/2023] Open
Abstract
Stenotrophomonas maltophilia, a gram-negative bacterium, has increasingly emerged as an important nosocomial pathogen. It is well-known for resistance to a variety of antimicrobial agents including cationic antimicrobial polypeptides (CAPs). Resistance to polymyxin B, a kind of CAPs, is known to be controlled by the two-component system PhoPQ. To unravel the role of PhoPQ in polymyxin B resistance of S. maltophilia, a phoP mutant was constructed. We found MICs of polymyxin B, chloramphenicol, ampicillin, gentamicin, kanamycin, streptomycin and spectinomycin decreased 2-64 fold in the phoP mutant. Complementation of the phoP mutant by the wild-type phoP gene restored all of the MICs to the wild type levels. Expression of PhoP was shown to be autoregulated and responsive to Mg2+ levels. The polymyxin B and gentamicin killing tests indicated that pretreatment of low Mg2+ can protect the wild-type S. maltophilia from killing but not phoP mutant. Interestingly, we found phoP mutant had a decrease in expression of SmeZ, an efflux transporter protein for aminoglycosides in S. maltophilia. Moreover, phoP mutant showed increased permeability in the cell membrane relative to the wild-type. In summary, we demonstrated the two-component regulator PhoP of S. maltophilia is involved in antimicrobial susceptibilities and low Mg2+ serves as a signal for triggering the pathway. Both the alteration in membrane permeability and downregulation of SmeZ efflux transporter in the phoP mutant contributed to the increased drug susceptibilities of S. maltophilia, in particular for aminoglycosides. This is the first report to describe the role of the Mg2+-sensing PhoP signaling pathway of S. maltophilia in regulation of the SmeZ efflux transporter and in antimicrobial susceptibilities. This study suggests PhoPQ TCS may serve as a target for development of antimicrobial agents against multidrug-resistant S. maltophilia.
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Affiliation(s)
- Ming-Che Liu
- Department and Graduate Institute of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China
| | - Yi-Lin Tsai
- Department and Graduate Institute of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China
| | - Yi-Wei Huang
- Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China
| | - Hsing-Yu Chen
- Department of Clinical Pathology, Taipei City Hospital Renai Branch, Taipei, Taiwan, Republic of China
| | - Po-Ren Hsueh
- Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan, Republic of China
| | - Szu-Yu Lai
- Department and Graduate Institute of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China
| | - Li-Chia Chen
- Department and Graduate Institute of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China
| | - Yi-Hwa Chou
- Department and Graduate Institute of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China
| | - Wen-Yuan Lin
- Department and Graduate Institute of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China
| | - Shwu-Jen Liaw
- Department and Graduate Institute of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China
- Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan, Republic of China
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13
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The Rcs regulon in Proteus mirabilis: implications for motility, biofilm formation, and virulence. Curr Genet 2016; 62:775-789. [DOI: 10.1007/s00294-016-0579-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 02/05/2016] [Accepted: 02/09/2016] [Indexed: 10/22/2022]
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14
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Abstract
Proteus mirabilis is a common human pathogen causing recurrent or persistent urinary tract infections (UTIs). The underlying mechanisms for P. mirabilis to establish UTIs are not fully elucidated. In this study, we showed that loss of the sigma factor E (RpoE), mediating extracytoplasmic stress responses, decreased fimbria expression, survival in macrophages, cell invasion, and colonization in mice but increased the interleukin-8 (IL-8) expression of urothelial cells and swarming motility. This is the first study to demonstrate that RpoE modulated expression of MR/P fimbriae by regulating mrpI, a gene encoding a recombinase controlling the orientation of MR/P fimbria promoter. By real-time reverse transcription-PCR, we found that the IL-8 mRNA amount of urothelial cells was induced significantly by lipopolysaccharides extracted from rpoE mutant but not from the wild type. These RpoE-associated virulence factors should be coordinately expressed to enhance the fitness of P. mirabilis in the host, including the avoidance of immune attacks. Accordingly, rpoE mutant-infected mice displayed more immune cell infiltration in bladders and kidneys during early stages of infection, and the rpoE mutant had a dramatically impaired ability of colonization. Moreover, it is noteworthy that urea (the major component in urine) and polymyxin B (a cationic antimicrobial peptide) can induce expression of rpoE by the reporter assay, suggesting that RpoE might be activated in the urinary tract. Altogether, our results indicate that RpoE is important in sensing environmental cues of the urinary tract and subsequently triggering the expression of virulence factors, which are associated with the fitness of P. mirabilis, to build up a UTI.
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Olaitan AO, Morand S, Rolain JM. Mechanisms of polymyxin resistance: acquired and intrinsic resistance in bacteria. Front Microbiol 2014; 5:643. [PMID: 25505462 PMCID: PMC4244539 DOI: 10.3389/fmicb.2014.00643] [Citation(s) in RCA: 927] [Impact Index Per Article: 92.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 11/07/2014] [Indexed: 01/06/2023] Open
Abstract
Polymyxins are polycationic antimicrobial peptides that are currently the last-resort antibiotics for the treatment of multidrug-resistant, Gram-negative bacterial infections. The reintroduction of polymyxins for antimicrobial therapy has been followed by an increase in reports of resistance among Gram-negative bacteria. Some bacteria, such as Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, develop resistance to polymyxins in a process referred to as acquired resistance, whereas other bacteria, such as Proteus spp., Serratia spp., and Burkholderia spp., are naturally resistant to these drugs. Reports of polymyxin resistance in clinical isolates have recently increased, including acquired and intrinsically resistant pathogens. This increase is considered a serious issue, prompting concern due to the low number of currently available effective antibiotics. This review summarizes current knowledge concerning the different strategies bacteria employ to resist the activities of polymyxins. Gram-negative bacteria employ several strategies to protect themselves from polymyxin antibiotics (polymyxin B and colistin), including a variety of lipopolysaccharide (LPS) modifications, such as modifications of lipid A with phosphoethanolamine and 4-amino-4-deoxy-L-arabinose, in addition to the use of efflux pumps, the formation of capsules and overexpression of the outer membrane protein OprH, which are all effectively regulated at the molecular level. The increased understanding of these mechanisms is extremely vital and timely to facilitate studies of antimicrobial peptides and find new potential drugs targeting clinically relevant Gram-negative bacteria.
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Affiliation(s)
- Abiola O Olaitan
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes CNRS-IRD UMR 6236, Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université Marseille, France
| | - Serge Morand
- Institut des Sciences de l'Evolution, CNRS-IRD-UM2, CC065, Université Montpellier 2 Montpellier, France
| | - Jean-Marc Rolain
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes CNRS-IRD UMR 6236, Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université Marseille, France
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16
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Identification of novel factors involved in modulating motility of Salmonella enterica serotype typhimurium. PLoS One 2014. [PMID: 25369209 DOI: 10.1371/journal.pone.0111513.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica serotype Typhimurium can move through liquid using swimming motility, and across a surface by swarming motility. We generated a library of targeted deletion mutants in Salmonella Typhimurium strain ATCC14028, primarily in genes specific to Salmonella, that we have previously described. In the work presented here, we screened each individual mutant from this library for the ability to move away from the site of inoculation on swimming and swarming motility agar. Mutants in genes previously described as important for motility, such as flgF, motA, cheY are do not move away from the site of inoculation on plates in our screens, validating our approach. Mutants in 130 genes, not previously known to be involved in motility, had altered movement of at least one type, 9 mutants were severely impaired for both types of motility, while 33 mutants appeared defective on swimming motility plates but not swarming motility plates, and 49 mutants had reduced ability to move on swarming agar but not swimming agar. Finally, 39 mutants were determined to be hypermotile in at least one of the types of motility tested. Both mutants that appeared non-motile and hypermotile on plates were assayed for expression levels of FliC and FljB on the bacterial surface and many of them had altered levels of these proteins. The phenotypes we report are the first phenotypes ever assigned to 74 of these open reading frames, as they are annotated as 'hypothetical genes' in the Typhimurium genome.
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Bogomolnaya LM, Aldrich L, Ragoza Y, Talamantes M, Andrews KD, McClelland M, Andrews-Polymenis HL. Identification of novel factors involved in modulating motility of Salmonella enterica serotype typhimurium. PLoS One 2014; 9:e111513. [PMID: 25369209 PMCID: PMC4219756 DOI: 10.1371/journal.pone.0111513] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 09/28/2014] [Indexed: 12/03/2022] Open
Abstract
Salmonella enterica serotype Typhimurium can move through liquid using swimming motility, and across a surface by swarming motility. We generated a library of targeted deletion mutants in Salmonella Typhimurium strain ATCC14028, primarily in genes specific to Salmonella, that we have previously described. In the work presented here, we screened each individual mutant from this library for the ability to move away from the site of inoculation on swimming and swarming motility agar. Mutants in genes previously described as important for motility, such as flgF, motA, cheY are do not move away from the site of inoculation on plates in our screens, validating our approach. Mutants in 130 genes, not previously known to be involved in motility, had altered movement of at least one type, 9 mutants were severely impaired for both types of motility, while 33 mutants appeared defective on swimming motility plates but not swarming motility plates, and 49 mutants had reduced ability to move on swarming agar but not swimming agar. Finally, 39 mutants were determined to be hypermotile in at least one of the types of motility tested. Both mutants that appeared non-motile and hypermotile on plates were assayed for expression levels of FliC and FljB on the bacterial surface and many of them had altered levels of these proteins. The phenotypes we report are the first phenotypes ever assigned to 74 of these open reading frames, as they are annotated as ‘hypothetical genes’ in the Typhimurium genome.
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Affiliation(s)
- Lydia M. Bogomolnaya
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, Texas, United States of America
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
| | - Lindsay Aldrich
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, Texas, United States of America
| | - Yuri Ragoza
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, Texas, United States of America
| | - Marissa Talamantes
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, Texas, United States of America
| | - Katharine D. Andrews
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, Texas, United States of America
| | - Michael McClelland
- Department of Microbiology and Molecular Genetics, University of California Irvine, Irvine, California, United States of America
| | - Helene L. Andrews-Polymenis
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University, Bryan, Texas, United States of America
- * E-mail:
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18
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Serratia marcescens arn, a PhoP-regulated locus necessary for polymyxin B resistance. Antimicrob Agents Chemother 2014; 58:5181-90. [PMID: 24957827 DOI: 10.1128/aac.00013-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Polymyxins, which are increasingly being used to treat infections caused by multidrug-resistant bacteria, perform poorly against Serratia marcescens. To investigate the underlying mechanisms, Tn5 mutagenesis was performed and two mutants exhibiting increased polymyxin B (PB) susceptibility were isolated. The mutants were found to have Tn5 inserted into the arnB and arnC genes. In other bacteria, arnB and arnC belong to the seven-gene arn operon, which is involved in lipopolysaccharide (LPS) modification. LPSs of arn mutants had greater PB-binding abilities than that of wild-type LPS. Further, we identified PhoP, a bacterial two-component response regulator, as a regulator of PB susceptibility in S. marcescens. By the reporter assay, we found PB- and low-Mg2+-induced expression of phoP and arn in the wild-type strain but not in the phoP mutant. Complementation of the phoP mutant with the full-length phoP gene restored the PB MIC and induction by PB and low Mg2+ levels, as in the wild type. An electrophoretic mobility shift assay (EMSA) further demonstrated that PhoP bound directly to the arn promoter. The PB challenge test confirmed that pretreatment with PB and low Mg2+ levels protected S. marcescens from a PB challenge in the wild-type strain but not in the phoP mutant. Real-time reverse transcriptase-PCR also indicated that PB serves as a signal to regulate expression of ugd, a gene required for LPS modification, in S. marcescens through a PhoP-dependent pathway. Finally, we found that PB-resistant clinical isolates displayed greater expression of arnA upon exposure to PB than did susceptible isolates. This is the first report to describe the role of S. marcescens arn in PB resistance and its modulation by PB and Mg2+ through the PhoP protein.
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Shanks RMQ, Lahr RM, Stella NA, Arena KE, Brothers KM, Kwak DH, Liu X, Kalivoda EJ. A Serratia marcescens PigP homolog controls prodigiosin biosynthesis, swarming motility and hemolysis and is regulated by cAMP-CRP and HexS. PLoS One 2013; 8:e57634. [PMID: 23469212 PMCID: PMC3585978 DOI: 10.1371/journal.pone.0057634] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 01/24/2013] [Indexed: 11/25/2022] Open
Abstract
Swarming motility and hemolysis are virulence-associated determinants for a wide array of pathogenic bacteria. The broad host-range opportunistic pathogen Serratia marcescens produces serratamolide, a small cyclic amino-lipid, that promotes swarming motility and hemolysis. Serratamolide is negatively regulated by the transcription factors HexS and CRP. Positive regulators of serratamolide production are unknown. Similar to serratamolide, the antibiotic pigment, prodigiosin, is regulated by temperature, growth phase, HexS, and CRP. Because of this co-regulation, we tested the hypothesis that a homolog of the PigP transcription factor of the atypical Serratia species ATCC 39006, which positively regulates prodigiosin biosynthesis, is also a positive regulator of serratamolide production in S. marcescens. Mutation of pigP in clinical, environmental, and laboratory strains of S. marcescens conferred pleiotropic phenotypes including the loss of swarming motility, hemolysis, and severely reduced prodigiosin and serratamolide synthesis. Transcriptional analysis and electrophoretic mobility shift assays place PigP in a regulatory pathway with upstream regulators CRP and HexS. The data from this study identifies a positive regulator of serratamolide production, describes novel roles for the PigP transcription factor, shows for the first time that PigP directly regulates the pigment biosynthetic operon, and identifies upstream regulators of pigP. This study suggests that PigP is important for the ability of S. marcescens to compete in the environment.
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Affiliation(s)
- Robert M. Q. Shanks
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh Eye Center, Pittsburgh, Pennsylvania, United States of America
| | - Roni M. Lahr
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh Eye Center, Pittsburgh, Pennsylvania, United States of America
| | - Nicholas A. Stella
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh Eye Center, Pittsburgh, Pennsylvania, United States of America
| | - Kristin E. Arena
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh Eye Center, Pittsburgh, Pennsylvania, United States of America
| | - Kimberly M. Brothers
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh Eye Center, Pittsburgh, Pennsylvania, United States of America
| | - Daniel H. Kwak
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Xinyu Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Eric J. Kalivoda
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh Eye Center, Pittsburgh, Pennsylvania, United States of America
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Armbruster CE, Mobley HLT. Merging mythology and morphology: the multifaceted lifestyle of Proteus mirabilis. Nat Rev Microbiol 2012; 10:743-54. [PMID: 23042564 DOI: 10.1038/nrmicro2890] [Citation(s) in RCA: 177] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Proteus mirabilis, named for the Greek god who changed shape to avoid capture, has fascinated microbiologists for more than a century with its unique swarming differentiation, Dienes line formation and potent urease activity. Transcriptome profiling during both host infection and swarming motility, coupled with the availability of the complete genome sequence for P. mirabilis, has revealed the occurrence of interbacterial competition and killing through a type VI secretion system, and the reciprocal regulation of adhesion and motility, as well as the intimate connections between metabolism, swarming and virulence. This Review addresses some of the unique and recently described aspects of P. mirabilis biology and pathogenesis, and emphasizes the potential role of this bacterium in single-species and polymicrobial urinary tract infections.
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Affiliation(s)
- Chelsie E Armbruster
- Department of Microbiology and Immunology, University of Michigan Medical School, 1150 West Medical Center Drive, 5641 Medical Science Building II, Ann Arbor, Michigan 48109, USA
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Role of the Umo proteins and the Rcs phosphorelay in the swarming motility of the wild type and an O-antigen (waaL) mutant of Proteus mirabilis. J Bacteriol 2011; 194:669-76. [PMID: 22139504 DOI: 10.1128/jb.06047-11] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proteus mirabilis is a Gram-negative bacterium that exists as a short rod when grown in liquid medium, but during growth on surfaces it undergoes a distinct physical and biochemical change that culminates in the formation of a swarmer cell. How P. mirabilis senses a surface is not fully understood; however, the inhibition of flagellar rotation and accumulation of putrescine have been proposed to be sensory mechanisms. Our lab recently isolated a transposon insertion in waaL, encoding O-antigen ligase, that resulted in a loss of swarming but not swimming motility. The waaL mutant failed to activate flhDC, the class 1 activator of the flagellar gene cascade, when grown on solid surfaces. Swarming in the waaL mutant was restored by overexpression of flhDC in trans or by a mutation in the response regulator rcsB. To further investigate the role of the Rcs signal transduction pathway and its possible relationship with O-antigen surface sensing, mutations were made in the rcsC, rcsB, rcsF, umoB (igaA), and umoD genes in wild-type and waaL backgrounds. Comparison of the swarming phenotypes of the single and double mutants and of strains overexpressing combinations of the UmoB, UmoD, and RcsF proteins demonstrated the following: (i) there is a differential effect of RcsF and UmoB on swarming in wild-type and waaL backgrounds, (ii) RcsF inhibits UmoB activity but not UmoD activity in a wild-type background, and (iii) UmoD is able to modulate activity of the Rcs system.
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22
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Chiu Y, Kuo TY, Lin CC, Chen WJ. Proteomic analysis reveals responsive proteins of Vibrio parahaemolyticus on exposure to cationic antimicrobial peptides. J Appl Microbiol 2010; 110:80-9. [PMID: 20880213 DOI: 10.1111/j.1365-2672.2010.04856.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To investigate whether Vibrio parahaemolyticus can sense and directly respond to the presence of cationic antimicrobial peptides (AMPs). METHODS AND RESULTS We performed proteomic methodologies to investigate the responsive proteins of V. parahaemolyticus on exposure to AMP Q6. Differential expression patterns of the outer membrane, inner membrane and cytoplasmic proteins (OMPs, IMPs and CPs) from the bacteria with or without Q6 treatment were obtained using two-dimensional gel electrophoresis (2-DE). Three OMPs (maltoporin, flagellin and OmpV), two IMPs (ATP synthase F1, alpha subunit; and OmpV) and three CPs (pyruvate dehydrogenase subunit E1, glyceraldehyde-3-phosphate dehydrogenase and inositol-5-monophosphate dehydrogenase) were identified using LC-ESI-Q-TOF MS/MS and Mascot program. Real-time quantitative polymerase chain reaction was also performed to determine the mRNA expression level of the target genes. CONCLUSIONS Our results suggested that V. parahaemolyticus may directly respond to AMPs through the upregulation of the efflux channel, increased yield of energy, effective repair of damaged membranes and downregulation of carbohydrate and nucleotide metabolism for energy preservation. SIGNIFICANCE AND IMPACT OF THE STUDY AMP-responsive proteins identified in the current study could serve as attractive targets for developing more effective antimicrobial agents.
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Affiliation(s)
- Y Chiu
- Graduate Institute of Biotechnology, College of Bioresources, National Ilan University, Ilan, Taiwan
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23
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Morgenstein RM, Szostek B, Rather PN. Regulation of gene expression during swarmer cell differentiation in Proteus mirabilis. FEMS Microbiol Rev 2010; 34:753-63. [PMID: 20497230 DOI: 10.1111/j.1574-6976.2010.00229.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The gram-negative bacterium Proteus mirabilis can exist in either of two cell types, a vegetative cell characterized as a short rod and a highly elongated and hyperflagellated swarmer cell. This differentiation is triggered by growth on solid surfaces and multiple inputs are sensed by the cell to initiate the differentiation process. These include the inhibition of flagellar rotation, the accumulation of extracellular putrescine and O-antigen interactions with a surface. A key event in the differentiation process is the upregulation of FlhD(2)C(2), which activates the flagellar regulon and additional genes required for differentiation. There are a number of genes that influence FlhD(2)C(2) expression and the function of these genes, if known, will be discussed in this review. Additional genes that have been shown to regulate gene expression during swarming will also be reviewed. Although P. mirabilis represents an excellent system to study microbial differentiation, it is largely understudied relative to other systems. Therefore, this review will also discuss some of the unanswered questions that are central to understanding this process in P. mirabilis.
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Affiliation(s)
- Randy M Morgenstein
- Department of Microbiology and Immunology, 3001 Rollins Research Center, Emory University, Atlanta, GA 30322, USA
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Characterization of UDP-glucose dehydrogenase and UDP-glucose pyrophosphorylase mutants of Proteus mirabilis: defectiveness in polymyxin B resistance, swarming, and virulence. Antimicrob Agents Chemother 2010; 54:2000-9. [PMID: 20160049 DOI: 10.1128/aac.01384-09] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Proteus mirabilis is known to be highly resistant to the action of polymyxin B (PB). However, the mechanism underlying PB resistance is not clear. In this study, we used Tn5 transposon mutagenesis to identify genes that may affect PB resistance in P. mirabilis. Two genes, ugd and galU, which may encode UDP-glucose dehydrogenase (Ugd) and UDP-glucose pyrophosphorylase (GalU), respectively, were identified. Knockout mutants of ugd and galU were found to be extremely sensitive to PB, presumably because of alterations in lipopolysaccharide (LPS) structure and cell surface architecture in these mutants. These mutants were defective in swarming, expressed lower levels of virulence factor hemolysin, and had lower cell invasion ability. Complementation of the ugd or galU mutant with the full-length ugd or galU gene, respectively, led to the restoration of wild-type phenotypic traits. Interestingly, we found that the expression of Ugd and GalU was induced by PB through RppA, a putative response regulator of the bacterial two-component system that we identified previously. Mutation in either ugd or galU led to activation of RpoE, an extracytoplasmic function sigma factor that has been shown to be activated by protein misfolding and alterations in cell surface structure in other bacteria. Activation of RpoE or RpoE overexpression was found to cause inhibition of FlhDC and hemolysin expression. To our knowledge, this is the first report describing the roles and regulation of Ugd and GalU in P. mirabilis.
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Proteus mirabilis pmrI, an RppA-regulated gene necessary for polymyxin B resistance, biofilm formation, and urothelial cell invasion. Antimicrob Agents Chemother 2010; 54:1564-71. [PMID: 20123999 DOI: 10.1128/aac.01219-09] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proteus mirabilis is naturally resistant to polymyxin B (PB). To investigate the underlying mechanisms, Tn5 mutagenesis was performed, and a mutant exhibiting increased PB susceptibility was isolated. The mutant was found to have Tn5 inserted into the PpmrI (Proteus pmrI) gene, a gene which may encode a UDP-glucuronic acid decarboxylase. In other bacteria, pmrI belongs to the seven-gene pmrF operon, which is involved in lipopolysaccharide (LPS) modification. While the PpmrI knockout mutant had a wild-type LPS profile and produced amounts of LPS similar to those produced by the wild type, LPS of the knockout mutant had higher PB-binding activity than that of the wild type. PB could induce alterations of LPS in the wild type but not in the PpmrI knockout mutant. Moreover, the PpmrI knockout mutant exhibited decreased abilities in biofilm formation and urothelial cell invasion. Complementation of the PpmrI mutant with the full-length PpmrI gene led to restoration of the wild-type phenotypic traits. Previously we identified RppA, a response regulator of the bacterial two-component system, as a regulator of PB susceptibility and virulence factor expression in P. mirabilis. Here we showed that RppA could mediate the induction of PpmrI expression by PB. An electrophoretic mobility shift assay further demonstrated that RppA could bind directly to the putative PpmrI promoter. Together, these results provide a new insight into the regulatory mechanism underlying PB resistance and virulence expression in P. mirabilis.
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Himpsl SD, Lockatell CV, Hebel JR, Johnson DE, Mobley HLT. Identification of virulence determinants in uropathogenic Proteus mirabilis using signature-tagged mutagenesis. J Med Microbiol 2008; 57:1068-1078. [PMID: 18719175 DOI: 10.1099/jmm.0.2008/002071-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The Gram-negative bacterium Proteus mirabilis causes urinary tract infections (UTIs) in individuals with long-term indwelling catheters or those with functional or structural abnormalities of the urinary tract. Known virulence factors include urease, haemolysin, fimbriae, flagella, DsbA, a phosphate transporter and genes involved in cell-wall synthesis and metabolism, many of which have been identified using the technique of signature-tagged mutagenesis (STM). To identify additional virulence determinants and to increase the theoretical coverage of the genome, this study generated and assessed 1880 P. mirabilis strain HI4320 mutants using this method. Mutants with disruptions in genes vital for colonization of the CBA mouse model of ascending UTI were identified after performing primary and secondary in vivo screens in approximately 315 CBA mice, primary and secondary in vitro screens in both Luria broth and minimal A medium to eliminate mutants with minor growth deficiencies, and co-challenge competition experiments in approximately 500 CBA mice. After completion of in vivo screening, a total of 217 transposon mutants were attenuated in the CBA mouse model of ascending UTI. Following in vitro screening, this number was reduced to 196 transposon mutants with a probable role in virulence. Co-challenge competition experiments confirmed significant attenuation for 37 of the 93 transposon mutants tested, being outcompeted by wild-type HI4320. Following sequence analysis of the 37 mutants, transposon insertions were identified in genes including the peptidyl-prolyl isomerases surA and ppiA, glycosyltransferase cpsF, biopolymer transport protein exbD, transcriptional regulator nhaR, one putative fimbrial protein, flagellar M-ring protein fliF and hook protein flgE, and multiple metabolic genes.
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Affiliation(s)
- Stephanie D Himpsl
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - C Virginia Lockatell
- Division of Infectious Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - J Richard Hebel
- Department of Epidemiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - David E Johnson
- Research Service, Department of Veteran Affairs, Baltimore, MD 21201, USA.,Division of Infectious Diseases, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Harry L T Mobley
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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