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İnat G, Sırıken B, Başkan C, Erol İ, Yıldırım T, Çiftci A. Quorum sensing systems and related virulence factors in Pseudomonas aeruginosa isolated from chicken meat and ground beef. Sci Rep 2021; 11:15639. [PMID: 34341384 PMCID: PMC8329004 DOI: 10.1038/s41598-021-94906-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 07/05/2021] [Indexed: 11/09/2022] Open
Abstract
The objective of this study was to evaluate 50 [chicken meat (n = 45) and ground beef (n = 5)] Pseudomonas aeruginosa isolates to determine the expression of the lasI and rhl QS systems, related virulence factors, and the presence of N-3-oxo-dodecanoyl homoserine lactone (AHL: 3-O-C12-HSL). For the isolation and identification of P. aeruginosa, conventional culture and oprL gene-based molecular techniques were used. In relation to QS systems, eight genes consisting of four intact and four internal (lasI/R, rhlI/R) genes were analyzed with PCR assay. The two QS systems genes in P. aeruginosa isolates from ground beef (80.00%) and chicken meat (76.00%) were present at quite high levels. The 3-O-C12-HSL was detected in 14.00% of the isolates. Both biofilm formation and motility were detected in 98.00% of the isolates. Protease activity was determined in 54.00% of the isolates. Pyocyanin production was detected in 48.00% of the isolates. The las system scores strongly and positively correlated with the rhl system (p ˂ .01). PYA moderately and positively correlated with protease (p ˂ .05). In addition, there was statistically significance between lasI and protease activity (p < .10), and rhlI and twitching motility (p < .10). In conclusion, the high number of isolates having QS systems and related virulence factors are critical for public health. Pyocyanin, protease, and biofilm formation can cause spoilage and play essential role in food spoilage and food safety.
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Affiliation(s)
- Gökhan İnat
- Department of Food Hygiene and Technology, Faculty of Veterinary Medicine, Ondokuz Mayıs University, Samsun, Turkey
| | - Belgin Sırıken
- Department of Aquatic Animal Diseases, Faculty of Veterinary Medicine, Ondokuz Mayıs University, Samsun, Turkey.
| | - Ceren Başkan
- Department of Physical Therapy and Rehabilitation, Sabuncuoğlu Şerefeddin Health Services Vocational School, Amasya University, Amasya, Turkey
| | - İrfan Erol
- Faculty of Health Sciences, Eastern Mediterranean University, Gazimagusa TRNC Via Mersin, Turkey
| | - Tuba Yıldırım
- Department of Biology, Faculty of Arts and Sciences, Amasya University, Amasya, Turkey
| | - Alper Çiftci
- Department of Microbiology, Faculty of Veterinary Medicine, Ondokuz Mayıs University, Samsun, Turkey
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Hoque F, Abraham TJ. Adhesion and colonization of potential probiont Pseudomonas aeruginosa FARP 72 in the intestine of yellowtail catfish, Pangasius pangasius. Arch Microbiol 2021; 203:2711-2717. [PMID: 33585990 DOI: 10.1007/s00203-021-02188-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 12/31/2020] [Accepted: 01/30/2021] [Indexed: 11/29/2022]
Abstract
Adhesion is recognized as the first important step of a probiont for intestinal colonization. This study assessed the ability of an antagonistic Pseudomonas aeruginosa FARP72 to adhere and colonize the intestine of yellowtail catfish, Pangasius pangasius both in vitro and in vivo. For the in vitro assay, the whole intestines of each of two starved P. pangasius were introduced separately into tubes containing bluish-green pigment-producing P. aeruginosa FARP72 at 8.00 log10 CFU/mL and physiological saline (0.85% sodium chloride) and incubated for 1 h at 30 ± 1 °C. The homogenate mucus solutions from the intestine samples were serially diluted and plated onto Pseudomonas isolation agar to determine the counts of bluish-green pigment-producing P. aeruginosa (BPPAC). The difference between the numbers of BPPAC and presumptive Pseudomonas counts (PPC) in the treated and control intestines was attributed to the adherence of P. aeruginosa FARP72. The levels of BPPAC and PPC in the treated intestines were 6.09 ± 0.59 log10 CFU/g. Similarly, following 30 days of feeding P. pangasius with P. aeruginosa FARP72 supplemented diet, the intestine of catfish recorded the BPPAC of 5.83 ± 0.64 log CFU/g. In control samples, the BPPACs were recorded as < 3.00 log10 CFU/g. The scanning electron micrograph of the intestines of P. pangasius following the in vitro and in vivo adhesion assays confirmed the ability of this bacterium to strongly adhere to the intestine, thus making it most suitable candidate probiont for use in freshwater catfish aquaculture.
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Affiliation(s)
- Farhana Hoque
- Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, 700094, West Bengal, India. .,Regional Research Station, ICAR-Central Institute of Freshwater Aquaculture, Rahara, Kolkata, 700118, West Bengal, India.
| | - T Jawahar Abraham
- Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, 700094, West Bengal, India
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Quorum sensing systems, related virulence factors, and biofilm formation in Pseudomonas aeruginosa isolated from fish. Arch Microbiol 2021; 203:1519-1528. [PMID: 33398400 DOI: 10.1007/s00203-020-02159-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/04/2020] [Accepted: 12/14/2020] [Indexed: 10/22/2022]
Abstract
In this study, two quorum sensing (QS) system genes, las and rhI; N-3-oxo-dodecanoyl homoserine lactone (AHL; 3-O-C12-HSL); and QS-related virulence factors and correlation between them were assessed in 30 fish origin P. aeruginosa isolates. The detection of two QS system of the isolates, and eight gene regions consisting of four intact (lasI/R, rhlI/R) and four internal (lasI/R, rhlI/R) genes were tested by PCR assay. According to findings, las and rhI QS system genes were detected in 27 and 30 isolates, respectively, while 3-O-C12-HSL was determined in 13 isolates. A total of 22, 27, and 18 isolates were capable of pyocyanin production, protease, and elastase activity, respectively. Biofilm formation was detected using three methods in all 30 isolates: 12 by Congo red agar, 14 by microtiter plate, and 29 by tube test. Twitching and swarming motility types were detected in 30, but the swimming motility was determined in 25 isolates. The rhI QS system genes detected in all of the isolates having three types including motility, PYA production, and protease and elastase activities. The las QS system genes were detected in 27 of the motility, 17 of PYA production, 25 of protease, and 16 of elastase activity having isolates. In conclusion, the high number of P. aeruginosa isolates from fish tested have two QS systems and related virulence factors. There was also correlation between them.
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Gerner E, Almqvist S, Werthén M, Trobos M. Sodium salicylate interferes with quorum-sensing-regulated virulence in chronic wound isolates of Pseudomonas aeruginosa in simulated wound fluid. J Med Microbiol 2020; 69:767-780. [PMID: 32320374 PMCID: PMC7451038 DOI: 10.1099/jmm.0.001188] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Introduction. An important factor for delayed healing of chronic wounds is the presence of bacteria. Quorum sensing (QS), a cell density-dependent signalling system, controls the production of many virulence factors and biofilm formation in Pseudomonas aeruginosa.Aim. Inhibition by sodium salicylate (NaSa) of QS-regulated virulence expression was evaluated in QS-characterized clinical wound isolates of P. aeruginosa, cultured in serum-containing medium.Methodology. Fourteen clinical P. aeruginosa strains from chronic wounds were evaluated for the production of QS signals and virulence factors. Inhibition of QS by NaSa in P. aeruginosa clinical strains, wild-type PAO1 and QS reporter strains was evaluated using in vitro assays for the production of biofilm, pyocyanin, siderophores, alkaline protease, elastase and stapholytic protease.Results. Six clinical strains secreted several QS-associated virulence factors and signal molecules and two were negative for all factors. Sub-inhibitory concentrations of NaSa downregulated the expression of the QS-related genes lasB, rhlA and pqsA and reduced the secretion of several virulence factors in PAO1 and clinical strains cultured in serum. Compared to serum-free media, the presence of serum increased the expression of QS genes and production of siderophores and pyocyanin but decreased biofilm formation.Conclusions. Pseudomonas aeruginosa from chronic wound infections showed different virulence properties. While very few strains showed no QS activity, approximately half were highly virulent and produced QS signals, suggesting that the targeting of QS is a viable and relevant strategy for infection control. NaSa showed activity as a QS-inhibitor by lowering the virulence phenotypes and QS signals at both transcriptional and extracellular levels.
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Affiliation(s)
- Erik Gerner
- Department of Biomaterials, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.,Mölnlycke Health Care AB, Gothenburg, Sweden.,Center for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden
| | | | - Maria Werthén
- Department of Biomaterials, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.,Center for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden.,Department of Health Sciences, University West, Trollhättan, Sweden
| | - Margarita Trobos
- Department of Biomaterials, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.,Center for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden
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Molecular Detection of Serine Carbapenemase Genes in Carbapenem-Resistant Isolates of Pseudomonas aeruginosa Recovered from Patients in Al-Diwaniyah Province, Iraq. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2019. [DOI: 10.22207/jpam.13.3.53] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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6
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Karami P, Mohajeri P, Yousefi Mashouf R, Karami M, Yaghoobi MH, Dastan D, Alikhani MY. Molecular characterization of clinical and environmental Pseudomonas aeruginosa isolated in a burn center. Saudi J Biol Sci 2018; 26:1731-1736. [PMID: 31762651 PMCID: PMC6864211 DOI: 10.1016/j.sjbs.2018.07.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 06/30/2018] [Accepted: 07/19/2018] [Indexed: 01/09/2023] Open
Abstract
In burn centers, Pseudomonas aeruginosa acts as a major cause of nosocomial infections. Therefore, this study aimed to characterize molecularly P. aeruginosa isolates collected from environmental samples and burn patients. A total of 78 strains (including 58 clinical and 20 environmental isolates) of the P. aeruginosa were collected from Beasat hospital of Hamadan, west of Iran, and was identified using API 20NE. The disk diffusion method according to the CLSI was applied for determination of the antimicrobial resistance. Moreover, the microtiter plate test was used for the quantification of Biofilm formation. The genomic features of the isolated strains was evaluated using Pulsed Field Gel Electrophoresis (PFGE). We found that 94.8% of clinical and 80% environmental isolates were capable of forming biofilm. The rate of MDR in clinical and environmental isolates was 51.7% and 40%, respectively. A significant relationship was observed between biofilm formation capability and multiple drug resistance (p < 0.05). PFGE typing showed 11 different clusters with two major clusters A with 30 (38.5%) and B with 14 (17.9%) members, containing up to 56.4% of all isolates. There was no relationship between biofilm formation ability and antibiotic resistance patterns with PFGE patterns. According to the results, the clonal spread of environmental P. aeruginosa isolates is associated with clinical isolates, and both environmental and clinical isolates are attributed to a high prevalence of the antibiotic resistance and biofilm formation ability. This study highlighted that the prevention programs should be implemented in the hospital environment to control the spread of P. aeruginosa in burn units.
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Affiliation(s)
- Pezhman Karami
- Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Parviz Mohajeri
- Department of Microbiology, Faculty of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Rasool Yousefi Mashouf
- Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Manoochehr Karami
- Department of Epidemiology, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mojtaba Hedayat Yaghoobi
- Department of Infectious Disease, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran
| | - Dara Dastan
- Department of Pharmacognosy and Pharmaceutical Biotechnology, School of Pharmacy, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mohammad Yousef Alikhani
- Department of Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.,Brucellosis Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
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Castelo-Branco DSCM, Silva ALD, Monteiro FOB, Guedes GMDM, Sales JA, Oliveira JSD, Maia Junior JE, Miranda SA, Sidrim JJC, Alencar LPD, Brilhante RSN, Cordeiro RDA, Bandeira TDJPG, Pereira Neto WDA, Rocha MFG. Aeromonas and Plesiomonas species from scarlet ibis (Eudocimus ruber) and their environment: monitoring antimicrobial susceptibility and virulence. Antonie van Leeuwenhoek 2016; 110:33-43. [DOI: 10.1007/s10482-016-0771-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/14/2016] [Indexed: 11/25/2022]
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8
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Ali SG, Ansari MA, Khan HM, Jalal M, Mahdi AA, Cameotra SS. Crataeva nurvala nanoparticles inhibit virulence factors and biofilm formation in clinical isolates of Pseudomonas aeruginosa. J Basic Microbiol 2016; 57:193-203. [PMID: 27874198 DOI: 10.1002/jobm.201600175] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 10/25/2016] [Indexed: 12/23/2022]
Abstract
Green synthesized nanoparticles have gained great attention due to their non-toxic and non-hazardous nature. In the present study, bark extract of the medicinal plant in Ayurveda Crataeva nurvala (Buch-Ham) (CN) was chosen for the biosynthesis of silver nanoparticles (AgNPs). These NPs were characterized by Ultra violet visible spectroscopy, Fourier Transform Infra Red, Atomic Force Microscopy, and Transmission Electron Microscopy (TEM). The average particle size of green synthesized CN-AgNPs was 15.2 ± 1.01 nm. Gas chromatography- mass spectrometry analysis of methanolic bark extract involved in the formation of CN-AgNPs revealed lupeol as a major active component. In this study, CN-AgNPs (15 μg ml-1 ) efficiently suppressed the production of quorum sensing mediated virulence factors viz. pyocyanin, protease, hemolysin, and biofilm formation in Pseudomonas aeruginosa. The pyocyanin production was strongly inhibited (74.64%) followed by proteolysis (47.3%) and hemolysin production (47.7%). However, the biofilm forming ability was maximally reduced up to 79.70%. Moreover, the Confocal Laser Scanning Microscopic Analysis showed that CN-AgNPs inhibit colonization of P. aeruginosa on to the surface. Furthermore, TEM analysis revealed internalization of CN-AgNPs inside the bacterial cell. It is concluded that green synthesized AgNPs have great potential to inhibit virulence factors and biofilm forming ability of drug-resistant clinical isolates of P. aeruginosa.
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Affiliation(s)
- Syed Ghazanfar Ali
- Department of Microbiology, Nanotechnology and Antimicrobial Drug Resistance Research Laboratory, Jawaharlal Nehru Medical College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Mohammad Azam Ansari
- Department of Microbiology, Nanotechnology and Antimicrobial Drug Resistance Research Laboratory, Jawaharlal Nehru Medical College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.,Department of Medical Laboratories, College of Applied Medical Science, Buraydah Colleges, Buraydah, Saudi Arabia
| | - Haris M Khan
- Department of Microbiology, Nanotechnology and Antimicrobial Drug Resistance Research Laboratory, Jawaharlal Nehru Medical College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Mohammad Jalal
- Department of Microbiology, Nanotechnology and Antimicrobial Drug Resistance Research Laboratory, Jawaharlal Nehru Medical College and Hospital, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Abbas Ali Mahdi
- Department of Biochemistry, King George Medical University, Lucknow, Uttar Pradesh, India
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Di Domenico EG, Toma L, Provot C, Ascenzioni F, Sperduti I, Prignano G, Gallo MT, Pimpinelli F, Bordignon V, Bernardi T, Ensoli F. Development of an in vitro Assay, Based on the BioFilm Ring Test ®, for Rapid Profiling of Biofilm-Growing Bacteria. Front Microbiol 2016; 7:1429. [PMID: 27708625 PMCID: PMC5030256 DOI: 10.3389/fmicb.2016.01429] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/29/2016] [Indexed: 01/05/2023] Open
Abstract
Microbial biofilm represents a major virulence factor associated with chronic and recurrent infections. Pathogenic bacteria embedded in biofilms are highly resistant to environmental and chemical agents, including antibiotics and therefore difficult to eradicate. Thus, reliable tests to assess biofilm formation by bacterial strains as well as the impact of chemicals or antibiotics on biofilm formation represent desirable tools for a most effective therapeutic management and microbiological risk control. Current methods to evaluate biofilm formation are usually time-consuming, costly, and hardly applicable in the clinical setting. The aim of the present study was to develop and assess a simple and reliable in vitro procedure for the characterization of biofilm-producing bacterial strains for future clinical applications based on the BioFilm Ring Test® (BRT) technology. The procedure developed for clinical testing (cBRT) can provide an accurate and timely (5 h) measurement of biofilm formation for the most common pathogenic bacteria seen in clinical practice. The results gathered by the cBRT assay were in agreement with the traditional crystal violet (CV) staining test, according to the κ coefficient test (κ = 0.623). However, the cBRT assay showed higher levels of specificity (92.2%) and accuracy (88.1%) as compared to CV. The results indicate that this procedure offers an easy, rapid and robust assay to test microbial biofilm and a promising tool for clinical microbiology.
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Affiliation(s)
- Enea G Di Domenico
- Clinical Pathology and Microbiology Department, San Gallicano Institute, Istituti di Ricovero e Cura a Carattere Scientifico Rome, Italy
| | - Luigi Toma
- Infectious Disease Consultant, San Gallicano Institute, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Rome, Italy
| | - Christian Provot
- BioFilm Control, Biopole Clermont Limagne Saint Beauzire, France
| | - Fiorentina Ascenzioni
- Department of Biology and Biotechnology C. Darwin, Sapienza University of Rome Rome, Italy
| | - Isabella Sperduti
- Biostatistics, San Gallicano Institute, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Rome, Italy
| | - Grazia Prignano
- Clinical Pathology and Microbiology Department, San Gallicano Institute, Istituti di Ricovero e Cura a Carattere Scientifico Rome, Italy
| | - Maria T Gallo
- Clinical Pathology and Microbiology Department, San Gallicano Institute, Istituti di Ricovero e Cura a Carattere Scientifico Rome, Italy
| | - Fulvia Pimpinelli
- Clinical Pathology and Microbiology Department, San Gallicano Institute, Istituti di Ricovero e Cura a Carattere Scientifico Rome, Italy
| | - Valentina Bordignon
- Clinical Pathology and Microbiology Department, San Gallicano Institute, Istituti di Ricovero e Cura a Carattere Scientifico Rome, Italy
| | - Thierry Bernardi
- BioFilm Control, Biopole Clermont Limagne Saint Beauzire, France
| | - Fabrizio Ensoli
- Clinical Pathology and Microbiology Department, San Gallicano Institute, Istituti di Ricovero e Cura a Carattere Scientifico Rome, Italy
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Suezawa C, Yasuda M, Negayama K, Kameyama T, Hirauchi M, Nakai T, Okuda J. Identification of genes associated with the penetration activity of the human type of Edwardsiella tarda EdwGII through human colon epithelial cell monolayers. Microb Pathog 2016; 95:148-156. [DOI: 10.1016/j.micpath.2016.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 03/28/2016] [Accepted: 04/01/2016] [Indexed: 11/27/2022]
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Mathee K, Silver LL, Tatke G. 70th Anniversary Collection for the Microbiology Society: Journal of Medical Microbiology. J Med Microbiol 2015; 64:1457-1461. [PMID: 26689963 DOI: 10.1099/jmm.0.000186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the last 70 years, we have seen a radical change in our perception and understanding of the microbial world. During this period, we learned from Woese and Fox there exists a third kingdom called 'Archea' based on the phylogenetic studies of the 16S rRNA that revolutionized microbiology (Woese & Fox, 1977; Woese et al., 1978). Furthermore, we were forced to reckon with the fact that Koch and Pasteur's way of growing cells in test-tubes or flasks planktonically does not necessarily translate to the real-life scenario of bacterial lifestyle, where they prefer to live and function as a closely knit microbial community called biofilm. Thanks are due to Costerton, who led the crusade on the concept of biofilms and expanded its scope of inquiry, which forced scientists and clinicians worldwide to rethink how we evaluate and apply the data. Then progressively, disbelief turned into belief, and now it is universally accepted that the micro-organisms hobnob with the members of their community to communicate and coordinate their behaviour, especially in regard to growth patterns and virulence traits via signalling molecules. Just when we thought that we were losing the battle against bacteria, antimicrobials were discovered. We then witnessed the rise and fall of antibiotics and the development of antibiotic resistance. Due to space and choice limitation, we will focus on the three areas that caused this major paradigm shift (i) antimicrobial resistance (AMR), (ii) biofilm and (iii) quorum sensing (QS), and how the Journal of Medical Microbiology played a major role in advancing the shift.
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Affiliation(s)
- Kalai Mathee
- Global Health Consortium, Florida International University, Miami, FL, USA.,Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | | | - Gorakh Tatke
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,Department of Biological Sciences, College of Arts & Sciences, Florida International University, Miami, FL, USA
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12
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Beringer PM, Bensman TJ, Ho H, Agnello M, Denovel N, Nguyen A, Wong-Beringer A, She R, Tran DQ, Moskowitz SM, Selsted ME. Rhesus θ-defensin-1 (RTD-1) exhibits in vitro and in vivo activity against cystic fibrosis strains of Pseudomonas aeruginosa. J Antimicrob Chemother 2015; 71:181-8. [PMID: 26433781 DOI: 10.1093/jac/dkv301] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Accepted: 08/23/2015] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES Chronic endobronchial infections with Pseudomonas aeruginosa contribute to bronchiectasis and progressive loss of lung function in patients with cystic fibrosis. This study aimed to evaluate the therapeutic potential of a novel macrocyclic peptide, rhesus θ-defensin-1 (RTD-1), by characterizing its in vitro antipseudomonal activity and in vivo efficacy in a murine model of chronic Pseudomonas lung infection. METHODS Antibacterial testing of RTD-1 was performed on 41 clinical isolates of P. aeruginosa obtained from cystic fibrosis patients. MIC, MBC, time-kill and post-antibiotic effects were evaluated following CLSI-recommended methodology, but using anion-depleted Mueller-Hinton broth. RTD-1 was nebulized daily for 7 days to cystic fibrosis transmembrane conductance regulator (CFTR) F508del-homozygous mice infected using the agar bead model of chronic P. aeruginosa lung infection. In vivo activity was evaluated by change in lung bacterial burden, airway leucocytes and body weight. RESULTS RTD-1 exhibited potent in vitro bactericidal activity against mucoid and non-mucoid strains of P. aeruginosa (MIC90 = 8 mg/L). Cross-resistance was not observed when tested against MDR and colistin-resistant isolates. Time-kill studies indicated very rapid, concentration-dependent bactericidal activity of RTD-1 with ≥3 log10 cfu/mL reductions at concentrations ≥4× MIC. No post-antibiotic effect was observed. In vivo, nebulized treatment with RTD-1 significantly decreased lung P. aeruginosa burden (mean difference of -1.30 log10 cfu; P = 0.0061), airway leucocytes (mean difference of -0.37 log10; P = 0.0012) and weight loss (mean difference of -12.62% at day 7; P < 0.05) when compared with controls. CONCLUSIONS This study suggests that RTD-1 is a promising potential therapeutic agent for cystic fibrosis airway disease.
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Affiliation(s)
- Paul M Beringer
- School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90033, USA
| | - Timothy J Bensman
- School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90033, USA
| | - Henry Ho
- School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90033, USA
| | - Melissa Agnello
- School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90033, USA
| | - Nicole Denovel
- School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90033, USA
| | - Albert Nguyen
- School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90033, USA
| | - Annie Wong-Beringer
- School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90033, USA
| | - Rosemary She
- Department of Pathology & Laboratory Medicine, Keck School of Medicine, University of Southern California, 2011 Zonal Avenue, Los Angeles, CA 90033, USA
| | - Dat Q Tran
- Department of Pathology & Laboratory Medicine, Keck School of Medicine, University of Southern California, 2011 Zonal Avenue, Los Angeles, CA 90033, USA
| | - Samuel M Moskowitz
- Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, 275 Cambridge Street, Boston, MA, USA
| | - Michael E Selsted
- Department of Pathology & Laboratory Medicine, Keck School of Medicine, University of Southern California, 2011 Zonal Avenue, Los Angeles, CA 90033, USA USC Norris Comprehensive Cancer Center, 1441 Eastlake Avenue, Los Angeles, CA, USA
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13
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Tran PL, Hamood AN, Reid TW. Antimicrobial Coatings to Prevent Biofilm Formation on Medical Devices. SPRINGER SERIES ON BIOFILMS 2014. [DOI: 10.1007/978-3-642-53833-9_9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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14
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Abstract
Our understanding of the virulence and pathogenesis of Francisella spp. has significantly advanced in recent years, including a new understanding that this organism can form biofilms. What is known so far about Francisella spp. biofilms is summarized here and future research questions are suggested. The molecular basis of biofilm production has begun to be studied, especially the role of extracellular carbohydrates and capsule, quorum sensing and two-component signaling systems. Further work has explored the contribution of amoebae, pili, outer-membrane vesicles, chitinases, and small molecules such as c-di-GMP to Francisella spp. biofilm formation. A role for Francisella spp. biofilm in feeding mosquito larvae has been suggested. As no strong role in virulence has been found yet, Francisella spp. biofilm formation is most likely a key mechanism for environmental survival and persistence. The significance and importance of Francisella spp.’s biofilm phenotype as a critical aspect of its microbial physiology is being developed. Areas for further studies include the potential role of Francisella spp. biofilms in the infection of mammalian hosts and virulence regulation.
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Affiliation(s)
- Monique L van Hoek
- School of Systems Biology and National Center for Biodefense and Infectious Diseases; George Mason University; Manassas, VA USA
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Cyclic voltammetric, fluorescence and biological analysis of purified aeruginosin A, a secreted red pigment of Pseudomonas aeruginosa PAO1. Microbiology (Reading) 2013; 159:1736-1747. [DOI: 10.1099/mic.0.065235-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Bruchmann J, Kirchen S, Schwartz T. Sub-inhibitory concentrations of antibiotics and wastewater influencing biofilm formation and gene expression of multi-resistant Pseudomonas aeruginosa wastewater isolates. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2013; 20:3539-49. [PMID: 23392972 DOI: 10.1007/s11356-013-1521-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 01/24/2013] [Indexed: 05/06/2023]
Abstract
Sub-inhibitory concentrations of antibiotics, which are found in environmental water systems and sewage plants due to an increased use in therapeutical and preventive fields, influence bacterial behavior in biofilms. The application of sulfamethoxazole, erythromycin, and roxithromycin induced changes in biofilm dynamics regarding biomass formation, spatial structure and specific gene expression in different Pseudomonas aeruginosa isolates. Exposing multi-resistant environmental isolated strains for 17 h to environmental concentrations of antibiotics or wastewater, directly, an increase in biofilm biomass and thickness could be observed for each strain. Additionally, multi-resistant strains responded to the applied growth conditions with changes in transcriptional activity. Here, sub-inhibitory concentrations of macrolides specifically upregulated expression of quorum sensing genes (rhlR, lasI), whereas sulfonamides and municipal wastewater, instead upregulated expression of specific resistant genes (sul1) and efflux pumps (mexD). Antibiotic sensitive isolates demonstrated an overall higher transcriptionally activity, but did not show a specific gene response to the applied exogenous stimuli. Furthermore, the presence of low concentrated antibiotics induced also phenotypical change in the biofilm architecture observed by 3D-imaging.
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Affiliation(s)
- Julia Bruchmann
- Karlsruhe Institute of Technology (KIT), Campus North, Institute of Functional Interfaces (IFG), Microbiology of Natural and Technical Interfaces Department, Herman-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
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17
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Doxycycline interferes with quorum sensing-mediated virulence factors and biofilm formation in gram-negative bacteria. World J Microbiol Biotechnol 2013; 29:949-57. [PMID: 23299903 DOI: 10.1007/s11274-013-1252-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 01/02/2013] [Indexed: 10/27/2022]
Abstract
Inhibition of quorum sensing (QS)-regulated virulence factors including biofilm is a recognized anti-pathogenic drug target. The search for safe and effective anti-QS agents is expected to be useful to combat diseases caused by multidrug-resistant bacteria. In this study, effect of a commonly used antibiotic, doxycycline on QS was evaluated using sensor strains of Chromobacterium violaceum (ATCC 12472 and CVO26) and Pseudomonas aeruginosa PAO1. Sub-MICs of doxycycline reduced QS-controlled violacein production in C. violaceum to a significant degree (70 %) and showed a significant reduction of LasB elastase (67.2 %), pyocyanin (69.1 %), chitinase (69.8 %) and protease (65 %) production and swarming motility (74 %) in P. aeruginosa PAO1 over untreated controls. Similar results were also recorded against a clinical strain of P. aeruginosa (PAF-79). Interestingly, doxycycline at respective sub-MICs (4 and 32 μg ml(-1)) significantly reduced the biofilm-forming capability and exopolysaccharide production in both the strains of P. aeruginosa (PAO1 and PAF-79) over untreated controls. The results of this study highlight the multiple actions of doxycycline against QS-linked traits/virulence factors and its potential to attenuate virulence of P. aeruginosa.
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Haley CL, Colmer-Hamood JA, Hamood AN. Characterization of biofilm-like structures formed by Pseudomonas aeruginosa in a synthetic mucus medium. BMC Microbiol 2012; 12:181. [PMID: 22900764 PMCID: PMC3494610 DOI: 10.1186/1471-2180-12-181] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 08/06/2012] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The accumulation of thick stagnant mucus provides a suitable environment for the growth of Pseudomonas aeruginosa and Staphylococcus aureus within the lung alveoli of cystic fibrosis (CF) patients. These infections cause significant lung damage, leading to respiratory failure and death. In an artificial mucin containing medium ASM+, P. aeruginosa forms structures that resemble typical biofilms but are not attached to any surface. We refer to these structures as biofilm like structures (BLS). Using ASM+ in a static microtiter plate culture system, we examined the roles of mucin, extracellular DNA, environmental oxygen (EO2), and quorum sensing (QS) in the development of biofilm-like structures (BLS) by P. aeruginosa; and the effect of EO2 and P. aeruginosa on S. aureus BLS. RESULTS Under 20% EO2, P. aeruginosa strain PAO1 produced BLS that resemble typical biofilms but are confined to the ASM+ and not attached to the surface. Levels of mucin and extracellular DNA within the ASM+ were optimized to produce robust well developed BLS. At 10% EO2, PAO1 produced thicker, more developed BLS, while under 0% EO2, BLS production was diminished. In contrast, the S. aureus strain AH133 produced well-developed BLS only under 20% EO2. In PAO1, loss of the QS system genes rhlI and rhlR affected the formation of BLS in ASM+ in terms of both structure and architecture. Whether co-inoculated into ASM+ with AH133, or added to established AH133 BLS, PAO1 eliminated AH133 within 48-56 h. CONCLUSIONS The thick, viscous ASM+, which contains mucin and extracellular DNA levels similar to those found in the CF lung, supports the formation of biofilm-like structures similar to the aggregates described within CF airways. Alterations in environmental conditions or in the QS genes of P. aeruginosa, as occurs naturally during the progression of CF lung infection, affect the architecture and quantitative structural features of these BLS. Thus, ASM+ provides an in vitro medium in which the effect of changing levels of substances produced by the host and the bacteria can be analyzed to determine the effect on such structures and on the susceptibility of the bacteria within the BLS to various treatments.
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Affiliation(s)
- Cecily L Haley
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, School of Medicine, Lubbock TX, USA
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Cady NC, McKean KA, Behnke J, Kubec R, Mosier AP, Kasper SH, Burz DS, Musah RA. Inhibition of biofilm formation, quorum sensing and infection in Pseudomonas aeruginosa by natural products-inspired organosulfur compounds. PLoS One 2012; 7:e38492. [PMID: 22715388 PMCID: PMC3371053 DOI: 10.1371/journal.pone.0038492] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Accepted: 05/08/2012] [Indexed: 01/10/2023] Open
Abstract
Using a microplate-based screening assay, the effects on Pseudomonas aeruginosa PAO1 biofilm formation of several S-substituted cysteine sulfoxides and their corresponding disulfide derivatives were evaluated. From our library of compounds, S-phenyl-L-cysteine sulfoxide and its breakdown product, diphenyl disulfide, significantly reduced the amount of biofilm formation by P. aeruginosa at levels equivalent to the active concentration of 4-nitropyridine-N-oxide (NPO) (1 mM). Unlike NPO, which is an established inhibitor of bacterial biofilms, our active compounds did not reduce planktonic cell growth and only affected biofilm formation. When used in a Drosophila-based infection model, both S-phenyl-L-cysteine sulfoxide and diphenyl disulfide significantly reduced the P. aeruginosa recovered 18 h post infection (relative to the control), and were non-lethal to the fly hosts. The possibility that the observed biofilm inhibitory effects were related to quorum sensing inhibition (QSI) was investigated using Escherichia coli-based reporters expressing P. aeruginosa lasR or rhIR response proteins, as well as an endogenous P. aeruginosa reporter from the lasI/lasR QS system. Inhibition of quorum sensing by S-phenyl-L-cysteine sulfoxide was observed in all of the reporter systems tested, whereas diphenyl disulfide did not exhibit QSI in either of the E. coli reporters, and showed very limited inhibition in the P. aeruginosa reporter. Since both compounds inhibit biofilm formation but do not show similar QSI activity, it is concluded that they may be functioning by different pathways. The hypothesis that biofilm inhibition by the two active compounds discovered in this work occurs through QSI is discussed.
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Affiliation(s)
- Nathaniel C. Cady
- College of Nanoscale Science and Engineering, State University of New York at Albany, Albany, New York, United States of America
| | - Kurt A. McKean
- Department of Biological Sciences, State University of New York at Albany, Albany, New York, United States of America
| | - Jason Behnke
- College of Nanoscale Science and Engineering, State University of New York at Albany, Albany, New York, United States of America
| | - Roman Kubec
- Department of Applied Chemistry, University of South Bohemia, Czech Republic
| | - Aaron P. Mosier
- College of Nanoscale Science and Engineering, State University of New York at Albany, Albany, New York, United States of America
| | - Stephen H. Kasper
- College of Nanoscale Science and Engineering, State University of New York at Albany, Albany, New York, United States of America
| | - David S. Burz
- Department of Chemistry, State University of New York at Albany, Albany, New York, United States of America
| | - Rabi A. Musah
- Department of Chemistry, State University of New York at Albany, Albany, New York, United States of America
- * E-mail:
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An organoselenium compound inhibits Staphylococcus aureus biofilms on hemodialysis catheters in vivo. Antimicrob Agents Chemother 2011; 56:972-8. [PMID: 22123688 DOI: 10.1128/aac.05680-11] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Colonization of central venous catheters (CVCs) by pathogenic bacteria leads to catheter-related bloodstream infections (CRBSIs). These colonizing bacteria form highly antibiotic-resistant biofilms. Staphylococcus aureus is one of the most frequently isolated pathogens in CRBSIs. Impregnating CVC surfaces with antimicrobial agents has various degrees of effectiveness in reducing the incidence of CRBSIs. We recently showed that organoselenium covalently attached to disks as an antibiofilm agent inhibited the development of S. aureus biofilms. In this study, we investigated the ability of an organoselenium coating on hemodialysis catheters (HDCs) to inhibit S. aureus biofilms in vitro and in vivo. S. aureus failed to develop biofilms on HDCs coated with selenocyanatodiacetic acid (SCAA) in either static or flowthrough continuous-culture systems. The SCAA coating also inhibited the development of S. aureus biofilms on HDCs in vivo for 3 days. The SCAA coating was stable and nontoxic to cell culture or animals. This new method for coating the internal and external surfaces of HDCs with SCAA has the potential to prevent catheter-related infections due to S. aureus.
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21
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Hammond AA, Miller KG, Kruczek CJ, Dertien J, Colmer-Hamood JA, Griswold JA, Horswill AR, Hamood AN. An in vitro biofilm model to examine the effect of antibiotic ointments on biofilms produced by burn wound bacterial isolates. Burns 2010; 37:312-21. [PMID: 21130579 DOI: 10.1016/j.burns.2010.09.017] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 09/20/2010] [Accepted: 09/26/2010] [Indexed: 01/17/2023]
Abstract
PURPOSE Topical treatment of burn wounds is essential as reduced blood supply in the burned tissues restricts the effect of systemic antibiotics. On the burn surface, microorganisms exist within a complex structure termed a biofilm, which enhances bacterial resistance to antimicrobial agents significantly. Since bacteria differ in their ability to develop biofilms, the susceptibility of these biofilms to topically applied antibiotics varies, making it essential to identify which topical antibiotics efficiently disrupt or prevent biofilms produced by these pathogens. Yet, a simple in vitro assay to compare the susceptibility of biofilms produced by burn wound isolates to different topical antibiotics has not been reported. METHODS Biofilms were developed by inoculating cellulose disks on agar plates with burn wound isolates and incubating for 24h. The biofilms were then covered for 24h with untreated gauze or gauze coated with antibiotic ointment and remaining microorganisms were quantified and visualized microscopically. RESULTS Mupirocin and triple antibiotic ointments significantly reduced biofilms produced by the Staphylococcus aureus and Pseudomonas aeruginosa burn wound isolates tested, as did gentamicin ointment, with the exception of one P. aeruginosa clinical isolate. CONCLUSIONS The described assay is a practical and reproducible approach to identify topical antibiotics most effective in eliminating biofilms produced by burn wound isolates.
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Affiliation(s)
- Adrienne A Hammond
- Department of Surgery, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
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Hammond A, Dertien J, Colmer-Hamood JA, Griswold JA, Hamood AN. Serum Inhibits P. aeruginosa Biofilm Formation on Plastic Surfaces and Intravenous Catheters. J Surg Res 2010; 159:735-46. [DOI: 10.1016/j.jss.2008.09.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Revised: 08/27/2008] [Accepted: 09/02/2008] [Indexed: 11/16/2022]
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Durham-Colleran MW, Verhoeven AB, van Hoek ML. Francisella novicida forms in vitro biofilms mediated by an orphan response regulator. MICROBIAL ECOLOGY 2010; 59:457-465. [PMID: 19763680 DOI: 10.1007/s00248-009-9586-9] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Accepted: 08/19/2009] [Indexed: 05/28/2023]
Abstract
Francisella tularensis is associated with water and waterways and infects many species of animals, insects, and protists. The mechanism Francisella utilizes to persist in the environment and in tick vectors is currently unknown. We have demonstrated for the first time that Francisella novicida, a model organism of F. tularensis, forms a biofilm in vitro. Selected F. novicida transposon mutants were tested for their ability to form biofilm compared to the wildtype F. novicida strain. Mutation of the putative qseB gene led to an impairment in the ability to form biofilm with no impairment in bacterial growth. A qseC mutant had impaired growth but demonstrated a marked impairment in biofilm production. Mutation in capC affected both bacterial growth and biofilm formation, but no biofilm production impairment was seen with capB or pilE mutants. A deletion mutant in the orphan response regulator FTN_1465, which we propose is the putative QseB, formed significantly less biofilm than the wildtype. When FTN_1465 was complemented back into the deletion mutant, biofilm formation was restored. Thus, the orphan response regulator FTN_1465 is an important factor in biofilm production in vitro in F. novicida. These results demonstrate that Francisella species are able to form biofilms in vitro, suggesting that biofilm formation may be important for the lifecycle of this organism.
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Affiliation(s)
- Meghan W Durham-Colleran
- MS 1HS Department of Molecular and Microbiology, National Center for Biodefense and Infectious Diseases, George Mason University, 10900 University Blvd, Manassas, VA 20110, USA
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Hannig C, Follo M, Hellwig E, Al-Ahmad A. Visualization of adherent micro-organisms using different techniques. J Med Microbiol 2010; 59:1-7. [PMID: 19815663 DOI: 10.1099/jmm.0.015420-0] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The visualization and quantification of adherent bacteria is still one of the most relevant topics in microbiology. Besides electron microscopic techniques such as transmission electron microscopy, scanning electron microscopy and environmental scanning electron microscopy, modern fluorescence microscopic approaches based on fluorogenic dyes offer detailed insight into bacterial biofilms. The aim of the present review was to provide an overview of the advantages and disadvantages of different methods for visualization of adherent bacteria with a special focus on the experiences gained in dental research.
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Affiliation(s)
- Christian Hannig
- Department of Operative Dentistry and Periodontology, University of Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany
| | - Marie Follo
- Department of Hematology and Oncology, Core Facility, Albert-Ludwig University, Freiburg, Germany
| | - Elmar Hellwig
- Department of Operative Dentistry and Periodontology, University of Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany
| | - Ali Al-Ahmad
- Department of Operative Dentistry and Periodontology, University of Freiburg, Hugstetter Str. 55, D-79106 Freiburg, Germany
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Abstract
In nature, the bulk of bacterial biomass is believed to exist as an adherent community of cells called a biofilm. Pseudomonas aeruginosa has become a model organism for studying this mode of growth. Over the past decade, significant strides have been made towards understanding biofilm development in P. aeruginosa and we now have a clearer picture of the mechanisms involved. Available evidence suggests that construction of these sessile communities proceeds by many different pathways, rather than a specific programme of biofilm development. A cell-to-cell communication mechanism known as quorum sensing (QS) has been found to play a role in P. aeruginosa biofilm formation. Because both QS and biofilms are impacted by the surrounding environment, understanding the full involvement of cell-to-cell signalling in establishing these complex communities represents a challenge. Nevertheless, under set conditions, several links between QS and biofilm formation have been recognized, which is the focus of this review. A role for antibiotics as alternative QS signalling molecules influencing biofilm development is also discussed.
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Affiliation(s)
- T R de Kievit
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada.
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Influence of quorum sensing and iron on twitching motility and biofilm formation in Pseudomonas aeruginosa. J Bacteriol 2007; 190:662-71. [PMID: 17993517 DOI: 10.1128/jb.01473-07] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Reducing iron (Fe) levels in a defined minimal medium reduced the growth yields of planktonic and biofilm Pseudomonas aeruginosa, though biofilm biomass was affected to the greatest extent and at FeCl3 concentrations where planktonic cell growth was not compromised. Highlighting this apparently greater need for Fe, biofilm growth yields were markedly reduced in a mutant unable to produce pyoverdine (and, so, deficient in pyoverdine-mediated Fe acquisition) at concentrations of FeCl3 that did not adversely affect biofilm yields of a pyoverdine-producing wild-type strain. Concomitant with the reduced biofilm yields at low Fe concentrations, P. aeruginosa showed enhanced twitching motility in Fe-deficient versus Fe-replete minimal media. A mutant deficient in low-Fe-stimulated twitching motility but normal as regards twitching motility on Fe-rich medium was isolated and shown to be disrupted in rhlI, whose product is responsible for synthesis of the N-butanoyl homoserine lactone (C4-HSL) quorum-sensing signal. In contrast to wild-type cells, which formed thin, flat, undeveloped biofilms in Fe-limited medium, the rhlI mutant formed substantially developed though not fully mature biofilms under Fe limitation. C4-HSL production increased markedly in Fe-limited versus Fe-rich P. aeruginosa cultures, and cell-free low-Fe culture supernatants restored the twitching motility of the rhlI mutant on Fe-limited minimal medium and stimulated the twitching motility of rhlI and wild-type P. aeruginosa on Fe-rich minimal medium. Still, addition of exogenous C4-HSL did not stimulate the twitching motility of either strain on Fe-replete medium, indicating that some Fe-regulated and RhlI/C4-HSL-dependent extracellular product(s) was responsible for the enhanced twitching motility (and reduced biofilm formation) seen in response to Fe limitation.
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