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Tran TT, Cole M, Tomas E, Scott A, Topp E. Potential selection and maintenance of manure-originated multi-drug resistant plasmids at sub-clinical concentrations for tetracycline family antibiotics. Can J Microbiol 2023; 69:339-350. [PMID: 37267627 DOI: 10.1139/cjm-2022-0240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The goal of this study was to (a) determine the minimum selection concentrations of tetracycline family antibiotics necessary to maintain plasmids carrying tetracycline-resistant genes and (b) correlate these results to environmental hotspot concentrations reported in previous studies. This study used two plasmids (pT295A and pT413A) originating from dairy manure in a surrogate Escherichia coli host CV601. The minimum selection concentrations of antibiotics tested in nutrient-rich medium were determined as follows: 0.1 mg/L for oxytetracycline, 0.45 mg/L for chlortetracycline, and 0.13-0.25 mg/L for tetracycline. Mixing oxytetracycline and chlortetracycline had minimum selection concentration values increased 2-fold compared to those in single antibiotic tests. Minimum selection concentrations found in this study were lower than reported environmental hotspot concentrations, suggesting that tetracycline family antibiotics were likely to be the driver for the selection and maintenance of these plasmids. Relatively high plasmid loss rates (>90%) were observed when culturing a strain carrying a tetracycline-resistant plasmid in antibiotic-free nutrient-rich and nutrient-defined media. Overall, results suggested that these plasmids can be maintained at concentrations environmentally relevant in wastewater treatment plants, sewage, manure, and manured soil; however, they are unstable and easily lost in the absence of antibiotics.
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Affiliation(s)
- Tam T Tran
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, ON N5V 4T3, Canada
- Department of Biology, University of Western Ontario, 1151 Richmond St, London, ON N6A 3K7, Canada
| | - Marlena Cole
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, ON N5V 4T3, Canada
| | - Emily Tomas
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, ON N5V 4T3, Canada
| | - Andrew Scott
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, ON N5V 4T3, Canada
| | - Edward Topp
- London Research and Development Centre, Agriculture and Agri-Food Canada, 1391 Sandford St, London, ON N5V 4T3, Canada
- Department of Biology, University of Western Ontario, 1151 Richmond St, London, ON N6A 3K7, Canada
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2
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Ong J, Godfrey R, Nazarian A, Tam J, Isaacson BM, Pasquina PF, Williams DL. Comparison of Staphylococcus aureus tolerance between antimicrobial blue light, levofloxacin, and rifampin. Front Microbiol 2023; 14:1158558. [PMID: 37303789 PMCID: PMC10248220 DOI: 10.3389/fmicb.2023.1158558] [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: 02/04/2023] [Accepted: 05/02/2023] [Indexed: 06/13/2023] Open
Abstract
Background Bacterial biofilms readily develop on all medical implants, including percutaneous osseointegrated (OI) implants. With the growing rate of antibiotic resistance, exploring alternative options for managing biofilm-related infections is necessary. Antimicrobial blue light (aBL) is a unique therapy that can potentially manage biofilm-related infections at the skin-implant interface of OI implants. Antibiotics are known to have antimicrobial efficacy disparities between the planktonic and biofilm bacterial phenotypes, but it is unknown if this characteristic also pertains to aBL. In response, we developed experiments to explore this aspect of aBL therapy. Methods We determined minimum bactericidal concentrations (MBCs) and antibiofilm efficacies for aBL, levofloxacin, and rifampin against Staphylococcus aureus ATCC 6538 planktonic and biofilm bacteria. Using student t-tests (p < 0.05), we compared the efficacy profiles between the planktonic and biofilm states for the three independent treatments and a levofloxacin + rifampin combination. Additionally, we compared antimicrobial efficacy patterns for levofloxacin and aBL against biofilms as dosages increased. Results aBL had the most significant efficacy disparity between the planktonic and biofilm phenotypes (a 2.5 log10 unit difference). However, further testing against biofilms revealed that aBL had a positive correlation between increasing efficacy and exposure time, while levofloxacin encountered a plateau. While aBL efficacy was affected the most by the biofilm phenotype, its antimicrobial efficacy did not reach a maximum. Discussion/conclusion We determined that phenotype is an important characteristic to consider when determining aBL parameters for treating OI implant infections. Future research would benefit from expanding these findings against clinical S. aureus isolates and other bacterial strains, as well as the safety of long aBL exposures on human cells.
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Affiliation(s)
- Jemi Ong
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, United States
| | - Rose Godfrey
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, United States
| | - Alexa Nazarian
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, United States
| | - Joshua Tam
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, United States
- Department of Dermatology, Harvard Medical School, Boston, MA, United States
| | - Brad M. Isaacson
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, United States
- The Geneva Foundation, Tacoma, WA, United States
- Department of Physical Medicine and Rehabilitation, The Musculoskeletal Injury Rehabilitation Research for Operational Readiness, Uniformed Services University, Bethesda, MD, United States
- The Center for Rehabilitation Sciences Research, Uniformed Services University, Bethesda, MD, United States
| | - Paul F. Pasquina
- The Center for Rehabilitation Sciences Research, Uniformed Services University, Bethesda, MD, United States
- Department of Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD, United States
| | - Dustin L. Williams
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, United States
- The Center for Rehabilitation Sciences Research, Uniformed Services University, Bethesda, MD, United States
- Department of Pathology, University of Utah, Salt Lake City, UT, United States
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Chen L, Fang D, Zhang J, Xiao X, Li N, Li Y, Wan M, Mao C. Nanomotors-loaded microneedle patches for the treatment of bacterial biofilm-related infections of wound. J Colloid Interface Sci 2023; 647:142-151. [PMID: 37247478 DOI: 10.1016/j.jcis.2023.05.080] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 05/04/2023] [Accepted: 05/13/2023] [Indexed: 05/31/2023]
Abstract
The biofilms formed by bacteria at the wound site can effectively protect the bacteria, which greatly weakens the effect of antibiotics. Herein, a microneedle patch for wound treatment is designed, which can effectively penetrate the biofilms in a physical way because of the penetration ability of the microneedles and the motion behavior of the nanomotors, and deliver bacterial quorum sensing inhibitor luteolin (Le) and nanomotors with multiple antibacterial properties within biofilms. Firstly, the nanomotors-loaded microneedle patches are prepared and characterized. The results of in vitro and in vivo experiments show that the microneedle patches have good biosafety and antibacterial properties. Among them, Le can inhibit the growth of biofilms. Further, under near-infrared (NIR) irradiation, the nanomotors loaded with photosensitizer ICG and nitric oxide (NO) donor L-arginine (L-Arg) can move in the biofilms under the double driving effect of photothermal and NO, and can give full play to the multiple anti-biological infection effects of photothermal therapy (PTT), photodynamic therapy (PDT) and NO, and finally realize the effective removal of biofilms and promote wound healing. The intervention of nanomotor technology has brought about a new therapeutic strategy for bacterial biofilm-related infection of wound.
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Affiliation(s)
- Lin Chen
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China
| | - Dan Fang
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China
| | - Junyue Zhang
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China
| | - Xiangyu Xiao
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China
| | - Nan Li
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China
| | - Yue Li
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China
| | - Mimi Wan
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.
| | - Chun Mao
- National and Local Joint Engineering Research Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210023, China.
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4
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Chen X, Zhou J, Qian Y, Zhao L. Antibacterial coatings on orthopedic implants. Mater Today Bio 2023; 19:100586. [PMID: 36896412 PMCID: PMC9988588 DOI: 10.1016/j.mtbio.2023.100586] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 02/01/2023] [Accepted: 02/14/2023] [Indexed: 02/17/2023] Open
Abstract
With the aging of population and the rapid improvement of public health and medical level in recent years, people have had an increasing demand for orthopedic implants. However, premature implant failure and postoperative complications frequently occur due to implant-related infections, which not only increase the social and economic burden, but also greatly affect the patient's quality of life, finally restraining the clinical use of orthopedic implants. Antibacterial coatings, as an effective strategy to solve the above problems, have been extensively studied and motivated the development of novel strategies to optimize the implant. In this paper, a variety of antibacterial coatings recently developed for orthopedic implants were briefly reviewed, with the focus on the synergistic multi-mechanism antibacterial coatings, multi-functional antibacterial coatings, and smart antibacterial coatings that are more potential for clinical use, thereby providing theoretical references for further fabrication of novel and high-performance coatings satisfying the complex clinical needs.
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Affiliation(s)
- Xionggang Chen
- Institute of Physics & Optoelectronics Technology, Baoji Advanced Titanium Alloys and Functional Coatings Cooperative Innovation Center, Baoji University of Arts and Sciences, Baoji, 721016, PR China
| | - Jianhong Zhou
- Institute of Physics & Optoelectronics Technology, Baoji Advanced Titanium Alloys and Functional Coatings Cooperative Innovation Center, Baoji University of Arts and Sciences, Baoji, 721016, PR China
| | - Yu Qian
- Institute of Physics & Optoelectronics Technology, Baoji Advanced Titanium Alloys and Functional Coatings Cooperative Innovation Center, Baoji University of Arts and Sciences, Baoji, 721016, PR China
| | - LingZhou Zhao
- Department of Stomatology, Air Force Medical Center, The Fourth Military Medical University, Beijing, 100142, PR China
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5
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The Hormetic Effect Observed for Benzalkonium Chloride and Didecyldimethylammonium Chloride in Serratia sp. HRI. Microorganisms 2023; 11:microorganisms11030564. [PMID: 36985138 PMCID: PMC10057160 DOI: 10.3390/microorganisms11030564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 02/10/2023] [Accepted: 02/21/2023] [Indexed: 03/03/2023] Open
Abstract
Hormesis, or the hormetic effect, is a dose- or concentration-dependent response characterised by growth stimulation at low concentrations and inhibition at high concentrations. The impact of sub-lethal levels of disinfectants on the growth of Serratia species is critical to understanding the increasing number of outbreaks caused by this pathogen in healthcare settings. Serratia sp. HRI and Serratia marcescens ATCC 13880 were cultivated in sub-lethal levels of benzalkonium chloride (BAC), Didecyldimethylammonium chloride (DDAC), and VirukillTM. The maximum specific growth rates, doubling times, and cell counts were compared. The results revealed significant increases in maximum specific growth rates and shorter doubling times for Serratia sp. HRI when cultivated in sub-lethal levels of BAC and DDAC. The significant stimulatory effect of sub-lethal levels of these disinfectants for Serratia sp. HRI represents the first time hormesis has been observed in a Gram-negative bacterium for any disinfectant. Furthermore, this study is the first to observe the hormetic effect after treatment with DDAC and the second study to date analysing the impact of sub-lethal levels of disinfectants on the growth of bacterial species.
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Raya D, Shreya A, Kumar A, Giri SK, Salem DR, Gnimpieba EZ, Gadhamshetty V, Dhiman SS. Molecular regulation of conditioning film formation and quorum quenching in sulfate reducing bacteria. Front Microbiol 2022; 13:1008536. [PMID: 36386676 PMCID: PMC9659907 DOI: 10.3389/fmicb.2022.1008536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 09/26/2022] [Indexed: 09/19/2023] Open
Abstract
Sensing surface topography, an upsurge of signaling biomolecules, and upholding cellular homeostasis are the rate-limiting spatio-temporal events in microbial attachment and biofilm formation. Initially, a set of highly specialized proteins, viz. conditioning protein, directs the irreversible attachment of the microbes. Later signaling molecules, viz. autoinducer, take over the cellular communication phenomenon, resulting in a mature microbial biofilm. The mandatory release of conditioning proteins and autoinducers corroborated the existence of two independent mechanisms operating sequentially for biofilm development. However, both these mechanisms are significantly affected by the availability of the cofactor, e.g., Copper (Cu). Generally, the Cu concentration beyond threshold levels is detrimental to the anaerobes except for a few species of sulfate-reducing bacteria (SRB). Remarkably SRB has developed intricate ways to resist and thrive in the presence of Cu by activating numerous genes responsible for modifying the presence of more toxic Cu(I) to Cu(II) within the periplasm, followed by their export through the outer membrane. Therefore, the determinants of Cu toxicity, sequestration, and transportation are reconnoitered for their contribution towards microbial adaptations and biofilm formation. The mechanistic details revealing Cu as a quorum quencher (QQ) are provided in addition to the three pathways involved in the dissolution of cellular communications. This review articulates the Machine Learning based data curing and data processing for designing novel anti-biofilm peptides and for an in-depth understanding of QQ mechanisms. A pioneering data set has been mined and presented on the functional properties of the QQ homolog in Oleidesulfovibrio alaskensis G20 and residues regulating the multicopper oxidase properties in SRB.
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Affiliation(s)
- Dheeraj Raya
- Department of Civil and Environmental Engineering, South Dakota Mines, Rapid City, SD, United States
- 2DBEST Research Center, South Dakota Mines, Rapid City, SD, United States
| | - Aritree Shreya
- Department of Civil and Environmental Engineering, South Dakota Mines, Rapid City, SD, United States
- 2DBEST Research Center, South Dakota Mines, Rapid City, SD, United States
| | - Anil Kumar
- Centre for Medical Biotechnology, Maharshi Dayanand University, Rohtak, Haryana, India
| | - Shiv Kumar Giri
- Department of Biotechnology, Maharaja Agrasen University, Baddi, Himachal Pradesh, India
| | - David R. Salem
- Chemical and Biological Engineering, South Dakota Mines, Rapid City, SD, United States
| | - Etienne Z. Gnimpieba
- 2DBEST Research Center, South Dakota Mines, Rapid City, SD, United States
- Department of Biomedical Engineering, University of South Dakota, Vermillion, SD, United States
| | - Venkataramana Gadhamshetty
- Department of Civil and Environmental Engineering, South Dakota Mines, Rapid City, SD, United States
- 2DBEST Research Center, South Dakota Mines, Rapid City, SD, United States
| | - Saurabh Sudha Dhiman
- Department of Civil and Environmental Engineering, South Dakota Mines, Rapid City, SD, United States
- 2DBEST Research Center, South Dakota Mines, Rapid City, SD, United States
- Department of Chemistry, Biology and Health Sciences, South Dakota Mines, Rapid City, SD, United States
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7
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Antibiotics Drive Expansion of Rare Pathogens in a Chronic Infection Microbiome Model. mSphere 2022; 7:e0031822. [PMID: 35972133 PMCID: PMC9599657 DOI: 10.1128/msphere.00318-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chronic (long-lasting) infections are globally a major and rising cause of morbidity and mortality. Unlike typical acute infections, chronic infections are ecologically diverse, characterized by the presence of a polymicrobial mix of opportunistic pathogens and human-associated commensals. To address the challenge of chronic infection microbiomes, we focus on a particularly well-characterized disease, cystic fibrosis (CF), where polymicrobial lung infections persist for decades despite frequent exposure to antibiotics. Epidemiological analyses point to conflicting results on the benefits of antibiotic treatment yet are confounded by the dependency of antibiotic exposures on prior pathogen presence, limiting their ability to draw causal inferences on the relationships between antibiotic exposure and pathogen dynamics. To address this limitation, we develop a synthetic infection microbiome model representing CF metacommunity diversity and benchmark on clinical data. We show that in the absence of antibiotics, replicate microbiome structures in a synthetic sputum medium are highly repeatable and dominated by oral commensals. In contrast, challenge with physiologically relevant antibiotic doses leads to substantial community perturbation characterized by multiple alternate pathogen-dominant states and enrichment of drug-resistant species. These results provide evidence that antibiotics can drive the expansion (via competitive release) of previously rare opportunistic pathogens and offer a path toward microbiome-informed conditional treatment strategies. IMPORTANCE We develop and clinically benchmark an experimental model of the cystic fibrosis (CF) lung infection microbiome to investigate the impacts of antibiotic exposures on chronic, polymicrobial infections. We show that a single experimental model defined by metacommunity data can partially recapitulate the diversity of individual microbiome states observed across a population of people with CF. In the absence of antibiotics, we see highly repeatable community structures, dominated by oral microbes. Under clinically relevant antibiotic exposures, we see diverse and frequently pathogen-dominated communities, and a nonevolutionary enrichment of antimicrobial resistance on the community scale, mediated by competitive release. The results highlight the potential importance of nonevolutionary (community-ecological) processes in driving the growing global crisis of increasing antibiotic resistance.
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8
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In Vitro Antioxidant, Antibacterial and Mechanisms of Action of Ethanolic Extracts of Five Tunisian Plants against Bacteria. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12105038] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Pistacia lentiscus, Rosmarinus officinalis, Erica multiflora, Calicotome villosa, and Phillyrea latifolia were considered important medicinal herbs and were used to treat various ailments. The present study was designed to evaluate the antioxidant and antimicrobial activities of ethanolic extracts (EEs). P. lentiscus and R. officinalis were the richest species in phenolic compounds. Similarly, both species showed the highest values of flavonoids. While the EEs of P. lentiscus, E. multiflora, and C. villosa had higher amounts of tannins. These phenolic compounds were evaluated by two different tests, namely diphenyl picrylhydrazyl (DPPH) and ferric iron-reducing power (FRAP). The IC50 values were found to be significant (p < 0.05) for P. lentiscus and E. multiflora. Similarly, both plants showed the highest ferric-reducing antioxidant power (FRAP). This study has been conducted to evaluate the antibacterial potential of EEs against selected bacteria—Gram-positive bacteria (Staphylococcus aureus ATCC 29213, Listeria monocytogenes ATCC 7644) and Gram-negative bacteria (Escherichia coli ATCC 8739, Salmonella typhimurium NCTC 6017)—and determine their modes of action. The ethanolic extracts inhibited bacterial growth by producing concentration-dependent zones of inhibition. Treatment with these extracts at their minimum inhibitory concentrations (MICs) showed a significant reduction (p < 0.05) in the viability of bacteria. The extracts did not induce total lysis. Bacteria organisms treated with EEs at MICs showed a significant (p < 0.05) loss of tolerance to NaCl (5%). Our results highlighted the use of plant extracts as natural antibacterials that can be safely used in health care and led to the understanding of the antibacterial mechanism of plant extracts.
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9
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Hartline CJ, Zhang R, Zhang F. Transient Antibiotic Tolerance Triggered by Nutrient Shifts From Gluconeogenic Carbon Sources to Fatty Acid. Front Microbiol 2022; 13:854272. [PMID: 35359720 PMCID: PMC8963472 DOI: 10.3389/fmicb.2022.854272] [Citation(s) in RCA: 2] [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: 01/13/2022] [Accepted: 02/22/2022] [Indexed: 12/04/2022] Open
Abstract
Nutrient shifts from glycolytic-to-gluconeogenic carbon sources can create large sub-populations of extremely antibiotic tolerant bacteria, called persisters. Positive feedback in Escherichia coli central metabolism was believed to play a key role in the formation of persister cells. To examine whether positive feedback in nutrient transport can also support high persistence to β-lactams, we performed nutrient shifts for E. coli from gluconeogenic carbon sources to fatty acid (FA). We observed tri-phasic antibiotic killing kinetics characterized by a transient period of high antibiotic tolerance, followed by rapid killing then a slower persister-killing phase. The duration of transient tolerance (3-44 h) varies with pre-shift carbon source and correlates strongly with the time needed to accumulate the FA degradation enzyme FadD after the shift. Additionally, FadD accumulation time and thus transient tolerance time can be reduced by induction of the glyoxylate bypass prior to switching, highlighting that two interacting feedback loops simultaneously control the length of transient tolerance. Our results demonstrate that nutrient switches along with positive feedback are not sufficient to trigger persistence in a majority of the population but instead triggers only a temporary tolerance. Additionally, our results demonstrate that the pre-shift metabolic state determines the duration of transient tolerance and that supplying glyoxylate can facilitate antibiotic killing of bacteria.
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Affiliation(s)
- Christopher J. Hartline
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, Saint Louis, MO, United States
| | - Ruixue Zhang
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, Saint Louis, MO, United States
| | - Fuzhong Zhang
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, Saint Louis, MO, United States
- Division of Biology and Biomedical Sciences, Washington University in St. Louis, Saint Louis, MO, United States
- Institute of Materials Science and Engineering, Washington University in St. Louis, Saint Louis, MO, United States
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Srinivasan R, Santhakumari S, Poonguzhali P, Geetha M, Dyavaiah M, Xiangmin L. Bacterial Biofilm Inhibition: A Focused Review on Recent Therapeutic Strategies for Combating the Biofilm Mediated Infections. Front Microbiol 2021; 12:676458. [PMID: 34054785 PMCID: PMC8149761 DOI: 10.3389/fmicb.2021.676458] [Citation(s) in RCA: 108] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 04/14/2021] [Indexed: 12/31/2022] Open
Abstract
Biofilm formation is a major concern in various sectors and cause severe problems to public health, medicine, and industry. Bacterial biofilm formation is a major persistent threat, as it increases morbidity and mortality, thereby imposing heavy economic pressure on the healthcare sector. Bacterial biofilms also strengthen biofouling, affecting shipping functions, and the offshore industries in their natural environment. Besides, they accomplish harsh roles in the corrosion of pipelines in industries. At biofilm state, bacterial pathogens are significantly resistant to external attack like antibiotics, chemicals, disinfectants, etc. Within a cell, they are insensitive to drugs and host immune responses. The development of intact biofilms is very critical for the spreading and persistence of bacterial infections in the host. Further, bacteria form biofilms on every probable substratum, and their infections have been found in plants, livestock, and humans. The advent of novel strategies for treating and preventing biofilm formation has gained a great deal of attention. To prevent the development of resistant mutants, a feasible technique that may target adhesive properties without affecting the bacterial vitality is needed. This stimulated research is a rapidly growing field for applicable control measures to prevent biofilm formation. Therefore, this review discusses the current understanding of antibiotic resistance mechanisms in bacterial biofilm and intensely emphasized the novel therapeutic strategies for combating biofilm mediated infections. The forthcoming experimental studies will focus on these recent therapeutic strategies that may lead to the development of effective biofilm inhibitors than conventional treatments.
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Affiliation(s)
- Ramanathan Srinivasan
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fujian, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fujian, China
| | - Sivasubramanian Santhakumari
- Department of Biochemistry and Molecular Biology, School of Life Sciences, Pondicherry University, Puducherry, India
| | | | - Mani Geetha
- PG Research and Department of Microbiology, St. Joseph's College of Arts and Science (Autonomous), Tamil Nadu, India
| | - Madhu Dyavaiah
- Department of Biochemistry and Molecular Biology, School of Life Sciences, Pondicherry University, Puducherry, India
| | - Lin Xiangmin
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fujian, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fujian, China.,Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fujian, China
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11
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Design of a novel antimicrobial peptide 1018M targeted ppGpp to inhibit MRSA biofilm formation. AMB Express 2021; 11:49. [PMID: 33770266 PMCID: PMC7997937 DOI: 10.1186/s13568-021-01208-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 03/15/2021] [Indexed: 12/11/2022] Open
Abstract
Methicillin-resistant staphylococcus aureus (MRSA) and its biofilm infection were considered as one of the main international health issues. There are still many challenges for treatment using traditional antibiotics. In this study, a mutant peptide of innate defense regulator (IDR-)1018 named 1018M was designed based on molecular docking and amino acid substitution technology. The antibacterial/biofilm activity and mechanisms against MRSA of 1018M were investigated for the first time. The minimum inhibitory concentration (MIC) of 1018M was reduced 1 time (MIC = 2 μg/mL) compared to IDR-1018. After treatment with 32 μg/mL 1018M for 24 h, the percentage of biofilm decreased by 78.9%, which was more effective than the parental peptide. The results of mechanisms exploration showed that 1018M was more potent than IDR-1018 at destructing bacterial cell wall, permeating cell membrane (20.4%–50.1% vs 1.45%–10.6%) and binding to stringent response signaling molecule ppGpp (increased 27.9%). Additionally, the peptides could also exert their activity by disrupting genomic DNA, regulating the expression of ppGpp metabolism and biofilm forming related genes (RSH, relP, relQ, rsbU, sigB, spA, codY, agrA and icaD). Moreover, the higher temperature, pH and pepsase stabilities provide 1018M better processing, storage and internal environmental tolerance. These data indicated that 1018M may be a potential candidate peptide for the treatment of MRSA and its biofilm infections.
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12
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Selveshwari S, Lele K, Dey S. Genomic signatures of UV resistance evolution in
Escherichia coli
depend on the growth phase during exposure. J Evol Biol 2021; 34:953-967. [DOI: 10.1111/jeb.13764] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 12/27/2020] [Accepted: 01/13/2021] [Indexed: 11/28/2022]
Affiliation(s)
- S Selveshwari
- Population Biology Laboratory, Biology Division Indian Institute of Science Education and Research Pune Maharashtra India
| | - Kasturi Lele
- Population Biology Laboratory, Biology Division Indian Institute of Science Education and Research Pune Maharashtra India
| | - Sutirth Dey
- Population Biology Laboratory, Biology Division Indian Institute of Science Education and Research Pune Maharashtra India
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13
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Combatting fungal biofilm formation by diffusive release of fluconazole from heptylamine plasma polymer coating. Biointerphases 2020; 15:061012. [PMID: 33339460 DOI: 10.1116/6.0000511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A drug-eluting coating applied onto biomedical devices and implants is an appropriate way to ensure that an inhibitory concentration of antimicrobial drugs is present at the device surface, thus preventing surface colonization and subsequent biofilm formation. In this study, a thin polymer coating was applied to materials, and it acted as a drug-delivery reservoir capable of surface delivery of the antifungal drug fluconazole to amounts up to 21 μg/cm2. The release kinetics into aqueous solution were quantified by UV spectroscopy and conformed to the Ritger-Peppas and Korsmeyer-Peppas model. Complementary microbiological assays were used to determine effectiveness against Candida albicans attachment and biofilm formation, and against the control heptylamine plasma polymer coating without drug loading, on which substantial fungal growth occurred. Fluconazole release led to marked antifungal activity in all assays, with log 1.6 reduction in CFUs/cm2. Cell viability assays and microscopy revealed that fungal cells attached to the fluconazole-loaded coating remained rounded and did not form hyphae and biofilm. Thus, in vitro screening results for fluconazole-releasing surface coatings showed efficacy in the prevention of the formation of Candida albicans biofilm.
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Oktyabrsky ON, Bezmaternykh KV, Smirnova GV, Tyulenev AV. Effect of resveratrol and quercetin on the susceptibility of Escherichia coli to antibiotics. World J Microbiol Biotechnol 2020; 36:167. [PMID: 33025172 DOI: 10.1007/s11274-020-02934-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 09/15/2020] [Indexed: 11/25/2022]
Abstract
Activities of plant polyphenols (PPs), resveratrol and quercetin, alone or in combination with four conventional antibiotics against Escherichia coli have been investigated. In medium without antibiotics, both polyphenols caused a dose-dependent growth inhibition. However, pretreatment with resveratrol (40 and 100 μg ml-1) and quercetin (40 μg ml-1) reduced the bacteriostatic effect of kanamycin, streptomycin, cefotaxime and partially of ciprofloxacin. With few exceptions, both PPs also reduced the bactericidal effect of tested antibiotics. Paradoxically, low doses of PPs enhanced the bactericidal effect of kanamycin and partially ciprofloxacin. Compared to quercetin, resveratrol showed a weaker effect on the induction of antioxidant genes and the resistance of E. coli to the oxidative stress generated by hydrogen peroxide treatment. Both polyphenols at high doses reduced membrane potential. Altogether, these findings suggest that the decrease in the bactericidal effect of antibiotics by high doses of polyphenols is mostly due to bacteriostatic action of the latter. In the case of quercetin, the contribution of its antioxidant activity for antibiotic protection may be significant. There is a growing interest in the use of plant-derived compounds to enhance the toxicity of traditional antibiotics. This and other studies show that, under certain conditions, the use of polyphenols as adjuvants may not exert the expected therapeutic effect, but rather to decrease antimicrobial activity of antibiotics.
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Affiliation(s)
- Oleg N Oktyabrsky
- Laboratory of Physiology and Genetics of Microorganisms, Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, ul. Golev 13, 614081, Perm, Russia.
| | - Ksenia V Bezmaternykh
- Laboratory of Physiology and Genetics of Microorganisms, Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, ul. Golev 13, 614081, Perm, Russia
| | - Galina V Smirnova
- Laboratory of Physiology and Genetics of Microorganisms, Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, ul. Golev 13, 614081, Perm, Russia
| | - Alexey V Tyulenev
- Laboratory of Physiology and Genetics of Microorganisms, Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, ul. Golev 13, 614081, Perm, Russia
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15
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Kumar P, Mahajan P, Kaur R, Gautam S. Nanotechnology and its challenges in the food sector: a review. MATERIALS TODAY. CHEMISTRY 2020; 17:100332. [PMID: 32835156 PMCID: PMC7386856 DOI: 10.1016/j.mtchem.2020.100332] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 06/29/2020] [Accepted: 07/01/2020] [Indexed: 05/05/2023]
Abstract
Antibacterial activity of nanoparticles has received significant attention worldwide because of their great physical and chemical stability, excellent magnetic properties, and large lattice constant values. These properties are predominate in the food science for enhancing the overall quality, shelf life, taste, flavor, process-ability, etc., of the food. Nanoparticles exhibit attractive antibacterial activity due to their increased specific surface area leading to enhanced surface reactivity. When nanoparticles are suspended in the biological culture, they encounter various biological interfaces, resulting from the presence of cellular moieties like DNA, proteins, lipids, polysaccharides, etc., which helps antibacterial properties in many ways. This paper reviews different methods used for the synthesis of nanoparticles but is specially focusing on the green synthesis methods owing to its non-toxic nature towards the environment. This review highlights their antibacterial application mainly in the food sector in the form of food-nanosensors, food-packaging, and food-additives. The possible mechanism of nanoparticles for their antibacterial behavior underlying the interaction of nano-particles with bacteria, (i) excessive ROS generation including hydrogen peroxide (H2O2), OH- (hydroxyl radicals), and O- 2 2 (peroxide); and (ii) precipitation of nano-particles on the bacterial exterior; which, disrupts the cellular activities, resulting in membranes disturbance. All these phenomena results in the inhibition of bacterial growth. Along with this, their current application and future perspectives in the food sector are also discussed. Nanoparticles help in destroying not only pathogens but also deadly fungi and viruses. Most importantly it is required to focus more on the crop processing and its containment to stop the post-harvesting loss. So, nanoparticles can act as a smart weapon towards the sustainable move.
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Affiliation(s)
- P Kumar
- Advanced Functional Materials Lab., Dr. S.S. Bhatnagar University Institute of Chemical Engineering & Technology, Panjab University, Chandigarh, 160 014, India
| | - P Mahajan
- Advanced Functional Materials Lab., Dr. S.S. Bhatnagar University Institute of Chemical Engineering & Technology, Panjab University, Chandigarh, 160 014, India
| | - R Kaur
- Advanced Functional Materials Lab., Dr. S.S. Bhatnagar University Institute of Chemical Engineering & Technology, Panjab University, Chandigarh, 160 014, India
| | - S Gautam
- Advanced Functional Materials Lab., Dr. S.S. Bhatnagar University Institute of Chemical Engineering & Technology, Panjab University, Chandigarh, 160 014, India
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Laws M, Shaaban A, Rahman KM. Antibiotic resistance breakers: current approaches and future directions. FEMS Microbiol Rev 2020; 43:490-516. [PMID: 31150547 PMCID: PMC6736374 DOI: 10.1093/femsre/fuz014] [Citation(s) in RCA: 139] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 05/30/2019] [Indexed: 12/15/2022] Open
Abstract
Infections of antibiotic-resistant pathogens pose an ever-increasing threat to mankind. The investigation of novel approaches for tackling the antimicrobial resistance crisis must be part of any global response to this problem if an untimely reversion to the pre-penicillin era of medicine is to be avoided. One such promising avenue of research involves so-called antibiotic resistance breakers (ARBs), capable of re-sensitising resistant bacteria to antibiotics. Although some ARBs have previously been employed in the clinical setting, such as the β-lactam inhibitors, we posit that the broader field of ARB research can yet yield a greater diversity of more effective therapeutic agents than have been previously achieved. This review introduces the area of ARB research, summarises the current state of ARB development with emphasis on the various major classes of ARBs currently being investigated and their modes of action, and offers a perspective on the future direction of the field.
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Affiliation(s)
- Mark Laws
- Institute of Pharmaceutical Sciences, School of Cancer and Pharmaceutical Sciences, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NH
| | - Ali Shaaban
- Institute of Pharmaceutical Sciences, School of Cancer and Pharmaceutical Sciences, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NH
| | - Khondaker Miraz Rahman
- Institute of Pharmaceutical Sciences, School of Cancer and Pharmaceutical Sciences, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NH
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Freiberg JA, Le Breton Y, Harro JM, Allison DL, McIver KS, Shirtliff ME. The Arginine Deiminase Pathway Impacts Antibiotic Tolerance during Biofilm-Mediated Streptococcus pyogenes Infections. mBio 2020; 11:e00919-20. [PMID: 32636245 PMCID: PMC7343988 DOI: 10.1128/mbio.00919-20] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/09/2020] [Indexed: 02/06/2023] Open
Abstract
Bacterial biofilms are responsible for a variety of serious human infections and are notoriously difficult to treat due to their recalcitrance to antibiotics. Further work is necessary to elicit a full understanding of the mechanism of this antibiotic tolerance. The arginine deiminase (ADI) pathway is responsible for bacterial pH maintenance and is highly expressed during biofilm growth in multiple bacterial species. Using the group A Streptococcus (GAS) as a model human pathogen, the ADI pathway was demonstrated to contribute to biofilm growth. The inability of antibiotics to reduce GAS populations when in a biofilm was demonstrated by in vitro studies and a novel animal model of nasopharyngeal infection. However, disruption of the ADI pathway returned GAS biofilms to planktonic levels of antibiotic sensitivity, suggesting the ADI pathway is influential in biofilm-related antibiotic treatment failure and provides a new strategic target for the treatment of biofilm infections in GAS and potentially numerous other bacterial species.IMPORTANCE Biofilm-mediated bacterial infections are a major threat to human health because of their recalcitrance to antibiotic treatment. Through the study of Streptococcus pyogenes, a significant human pathogen that is known to form antibiotic-tolerant biofilms, we demonstrated the role that a bacterial pathway known for responding to acid stress plays in biofilm growth and antibiotic tolerance. This not only provides some insight into antibiotic treatment failure in S. pyogenes infections but also, given the widespread nature of this pathway, provides a potentially broad target for antibiofilm therapies. This discovery has the potential to impact the treatment of many different types of recalcitrant biofilm infections.
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Affiliation(s)
- Jeffrey A Freiberg
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
| | - Yoann Le Breton
- Department of Cell Biology & Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Janette M Harro
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
| | - Devon L Allison
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
| | - Kevin S McIver
- Department of Cell Biology & Molecular Genetics and Maryland Pathogen Research Institute, University of Maryland, College Park, Maryland, USA
| | - Mark E Shirtliff
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
- Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Baltimore, Maryland, USA
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18
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Mc Carlie S, Boucher CE, Bragg RR. Molecular basis of bacterial disinfectant resistance. Drug Resist Updat 2019; 48:100672. [PMID: 31830738 DOI: 10.1016/j.drup.2019.100672] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/19/2019] [Accepted: 11/22/2019] [Indexed: 01/08/2023]
Abstract
Antibiotic resistance could accelerate humanity towards an already fast-approaching post-antibiotic era, where disinfectants and effective biosecurity measures will be critically important to control microbial diseases. Disinfectant resistance has the potential to change our way of life from compromising food security to threatening our medical health systems. Resistance to antimicrobial agents occurs through either intrinsic or acquired resistance mechanisms. Acquired resistance occurs through the efficient transfer of mobile genetic elements, which can carry single, or multiple resistance determinants. Drug resistance genes may form part of integrons, transposons and insertions sequences which are capable of intracellular transfer onto plasmids or gene cassettes. Thereafter, resistance plasmids and gene cassettes mobilize by self-transmission between bacteria, increasing the prevalence of drug resistance determinants in a bacterial population. An accumulation of drug resistance genes through these mechanisms gives rise to multidrug resistant (MDR) bacteria. The study of this mobility is integral to safeguard current antibiotics, disinfectants and other antimicrobials. Literature evidence, however, indicates that knowledge regarding disinfectant resistance is severly limited. Genome engineering such as the CRISPR-Cas system, has identified disinfectant resistance genes, and reversed resistance altogether in certain prokaryotes. Demonstrating that these techniques could prove invaluable in the combat against disinfectant resistance by uncovering the secrets of MDR bacteria.
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19
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Anderson EM, Sychantha D, Brewer D, Clarke AJ, Geddes-McAlister J, Khursigara CM. Peptidoglycomics reveals compositional changes in peptidoglycan between biofilm- and planktonic-derived Pseudomonas aeruginosa. J Biol Chem 2019; 295:504-516. [PMID: 31771981 DOI: 10.1074/jbc.ra119.010505] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 11/25/2019] [Indexed: 12/14/2022] Open
Abstract
Peptidoglycan (PG) is a critical component of the bacterial cell wall and is composed of a repeating β-1,4-linked disaccharide of N-acetylglucosamine and N-acetylmuramic acid appended with a highly conserved stem peptide. In Gram-negative bacteria, PG is assembled in the cytoplasm and exported into the periplasm where it undergoes considerable maturation, modification, or degradation depending on the growth phase or presence of environmental stressors. These modifications serve important functions in diverse processes, including PG turnover, cell elongation/division, and antibiotic resistance. Conventional methods for analyzing PG composition are complex and time-consuming. We present here a streamlined MS-based method that combines differential analysis with statistical 1D annotation approaches to quantitatively compare PGs produced in planktonic- and biofilm-cultured Pseudomonas aeruginosa We identified a core assembly of PG that is present in high abundance and that does not significantly differ between the two growth states. We also identified an adaptive PG assembly that is present in smaller amounts and fluctuates considerably between growth states in response to physiological changes. Biofilm-derived adaptive PG exhibited significant changes compared with planktonic-derived PG, including amino acid substitutions of the stem peptide and modifications that indicate changes in the activity of amidases, deacetylases, and lytic transglycosylases. The results of this work also provide first evidence of de-N-acetylated muropeptides from P. aeruginosa The method developed here offers a robust and reproducible workflow for accurately determining PG composition in samples that can be used to assess global PG fluctuations in response to changing growth conditions or external stimuli.
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Affiliation(s)
- Erin M Anderson
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada
| | - David Sychantha
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada
| | - Dyanne Brewer
- Mass Spectrometry Facility, University of Guelph, Ontario N1G 2W1, Canada
| | - Anthony J Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada
| | - Jennifer Geddes-McAlister
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada; Mass Spectrometry Facility, University of Guelph, Ontario N1G 2W1, Canada.
| | - Cezar M Khursigara
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1, Canada; Mass Spectrometry Facility, University of Guelph, Ontario N1G 2W1, Canada.
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20
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Mullis MM, Rambo IM, Baker BJ, Reese BK. Diversity, Ecology, and Prevalence of Antimicrobials in Nature. Front Microbiol 2019; 10:2518. [PMID: 31803148 PMCID: PMC6869823 DOI: 10.3389/fmicb.2019.02518] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 10/18/2019] [Indexed: 12/15/2022] Open
Abstract
Microorganisms possess a variety of survival mechanisms, including the production of antimicrobials that function to kill and/or inhibit the growth of competing microorganisms. Studies of antimicrobial production have largely been driven by the medical community in response to the rise in antibiotic-resistant microorganisms and have involved isolated pure cultures under artificial laboratory conditions neglecting the important ecological roles of these compounds. The search for new natural products has extended to biofilms, soil, oceans, coral reefs, and shallow coastal sediments; however, the marine deep subsurface biosphere may be an untapped repository for novel antimicrobial discovery. Uniquely, prokaryotic survival in energy-limited extreme environments force microbial populations to either adapt their metabolism to outcompete or produce novel antimicrobials that inhibit competition. For example, subsurface sediments could yield novel antimicrobial genes, while at the same time answering important ecological questions about the microbial community.
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Affiliation(s)
- Megan M. Mullis
- Department of Life Sciences, Texas A&M University Corpus Christi, Corpus Christi, TX, United States
| | - Ian M. Rambo
- Department of Marine Science, University of Texas Marine Science Institute, Port Aransas, TX, United States
| | - Brett J. Baker
- Department of Marine Science, University of Texas Marine Science Institute, Port Aransas, TX, United States
| | - Brandi Kiel Reese
- Department of Life Sciences, Texas A&M University Corpus Christi, Corpus Christi, TX, United States
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21
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Kumari S, Das S. Expression of metallothionein encoding gene bmtA in biofilm-forming marine bacterium Pseudomonas aeruginosa N6P6 and understanding its involvement in Pb(II) resistance and bioremediation. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:28763-28774. [PMID: 31376126 DOI: 10.1007/s11356-019-05916-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 07/03/2019] [Indexed: 06/10/2023]
Abstract
The genetic basis and biochemical aspects of heavy metal endurance abilities have been precisely studied in planktonic bacteria; however, in nature, bacteria mostly grows as surface-attached communities called biofilms. A hallmark trait of biofilm is increased resistance to heavy metals compared with the resistance of planktonic bacteria. A proposed mechanism that contributes to this increased resistance is the enhanced expression of metal-resistant genes. bmtA gene coding for metallothionein protein is one such metal-resistant gene found in many bacterial spp. In the present study, lead (Pb) remediation potential of a biofilm-forming marine bacterium Pseudomonas aeruginosa N6P6 was explored. Biofilm-forming marine bacterium P. aeruginosa N6P6 possess bmtA gene and shows resistance towards many heavy metals, i.e., Pb, Cd, Hg, Cr, and Zn. The expression of metallothionein encoding gene bmtA is significantly high in 48-h-old biofilm culture (11. 4 fold) followed by 24-h-old biofilm culture of P. aeruginosa N6P6 (4.7 fold) (P < 0.05). However, in the case of planktonically grown culture of P. aeruginosa N6P6, the highest expression of bmtA gene was observed in 24-h-old culture. The expression of bmtA also increased significantly with increase in Pb concentration up to 800 ppm. CSLM analysis indicated significant reduction in the raw integrated density of biofilm-associated lipids and polysaccharides (PS) of P. aeruginosa N6P6 biofilm grown in Pb (sub-lethal concentration)-amended medium (P < 0.05), whereas no significant reduction was observed in the raw integrated density of EPS-associated protein. The role of bmtA gene as Pb(II)-resistant determinant was characterized by overexpressing the bmtA gene derived from P. aeruginosa N6P6 in Escherichia coli BL21(DE3). ESI-MS and SDS-PAGE analyses validated the presence of 11.5-kDa MT protein isolated from Pb(II)-induced recombinant E. coli BL21(DE3) harboring bmtA gene.
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Affiliation(s)
- Supriya Kumari
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, Odisha, 769 008, India
| | - Surajit Das
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology, Rourkela, Odisha, 769 008, India.
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22
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Cooper R, Kirketerp-Møller K. Non-antibiotic antimicrobial interventions and antimicrobial stewardship in wound care. J Wound Care 2019; 27:355-377. [PMID: 29883284 DOI: 10.12968/jowc.2018.27.6.355] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Control of wound infection today relies largely on antibiotics, but the continual emergence of antibiotic-resistant microorganisms threatens a return to the pre-antibiotic era when physicians used antiseptics to prevent and manage infection. Some of those antiseptics are still used today, and others have become available. A diverse variety of non-antibiotic antimicrobial interventions are found on modern formularies. Unlike the mode of action of antibiotics, which affect specific cellular target sites of pathogens, many non-antibiotic antimicrobials affect multiple cellular target sites in a non-specific way. Although this reduces the likelihood of selecting for resistant strains of microorganisms, some have emerged and cross-resistance between antibiotics and antiseptics has been detected. With the prospect of a post-antibiotic era looming, ways to maintain and extend our antimicrobial armamentarium must be found. In this narrative review, current and emerging non-antibiotic antimicrobial strategies will be considered and the need for antimicrobial stewardship in wound care will be explained.
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Affiliation(s)
- Rose Cooper
- Professor of Microbiology, Department of Biomedical Science, Cardiff School of Health Sciences, Cardiff Metropolitan University, Western Avenue, Cardiff, UK
| | - Klaus Kirketerp-Møller
- Orthopaedic Surgeon, Copenhagen Wound Healing Center, Department of Dermatology and Wounds, Bispebjerg University Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen NV
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23
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Biofilms: The Microbial "Protective Clothing" in Extreme Environments. Int J Mol Sci 2019; 20:ijms20143423. [PMID: 31336824 PMCID: PMC6679078 DOI: 10.3390/ijms20143423] [Citation(s) in RCA: 387] [Impact Index Per Article: 77.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 07/04/2019] [Accepted: 07/11/2019] [Indexed: 02/07/2023] Open
Abstract
Microbial biofilms are communities of aggregated microbial cells embedded in a self-produced matrix of extracellular polymeric substances (EPS). Biofilms are recalcitrant to extreme environments, and can protect microorganisms from ultraviolet (UV) radiation, extreme temperature, extreme pH, high salinity, high pressure, poor nutrients, antibiotics, etc., by acting as "protective clothing". In recent years, research works on biofilms have been mainly focused on biofilm-associated infections and strategies for combating microbial biofilms. In this review, we focus instead on the contemporary perspectives of biofilm formation in extreme environments, and describe the fundamental roles of biofilm in protecting microbial exposure to extreme environmental stresses and the regulatory factors involved in biofilm formation. Understanding the mechanisms of biofilm formation in extreme environments is essential for the employment of beneficial microorganisms and prevention of harmful microorganisms.
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24
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Smirnova GV, Oktyabrsky ON. Relationship between Escherichia coli growth rate and bacterial susceptibility to ciprofloxacin. FEMS Microbiol Lett 2019; 365:4705891. [PMID: 29228224 DOI: 10.1093/femsle/fnx254] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 11/30/2017] [Indexed: 01/07/2023] Open
Abstract
The effect of Escherichia coli growth rate on its susceptibility to ciprofloxacin was investigated using bacteria grown on different carbon sources and harboring mutations in genes encoding tricarboxylic acid cycle enzymes. A 1-h treatment of the wild type (wt) grown on glucose, succinate, malate, α-ketoglutarate or acetate with 0.3 μg ml-1 ciprofloxacin decreased the number of surviving cells (CFU ml-1), 560, 110, 74, 62 and 5 times, respectively. Among the mutants tested, sucB strain, which grew 1.75 times slower than wt, was 7.4-fold more tolerant to 0.3 μg ml-1 of ciprofloxacin than wt. Strong inverse correlations between log(CFU ml-1) after 1-h exposure to 0.3 and 3.0 μg ml-1 ciprofloxacin and the specific growth rate prior to antibiotic treatment (r = - 0.93 and -0.96, respectively) were observed. Data from the current and previous studies on the inhibitory effect of ciprofloxacin on cultures exhibiting a wide range of growth rates (0.01-1.3 h-1) were collated. Statistical analysis revealed a significant inverse correlation between log(CFU ml-1) after exposure to 3.0 μg ml-1 of ciprofloxacin and the specific bacterial growth rate prior to antibiotic exposure (r = -0.92). These data may be used in a design of antibiotic treatment protocols.
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Affiliation(s)
- Galina V Smirnova
- Laboratory of Physiology and Genetics of Microorganisms, Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Perm 614081, Russia
| | - Oleg N Oktyabrsky
- Laboratory of Physiology and Genetics of Microorganisms, Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Perm 614081, Russia.,Department of Chemistry and Biotechnology, Perm National Research Polytechnic University, Perm 614990, Russia
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25
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Marques CNH, Nelson SM. Pharmacodynamics of ciprofloxacin against Pseudomonas aeruginosa planktonic and biofilm-derived cells. Lett Appl Microbiol 2019; 68:350-359. [PMID: 30740751 DOI: 10.1111/lam.13126] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 02/05/2019] [Accepted: 02/06/2019] [Indexed: 02/03/2023]
Abstract
The influence of growth phase and state on the survival and recovery of Pseudomonas aeruginosa exposed to ciprofloxacin was investigated using batch culture grown planktonic cells and disaggregated biofilm populations. Biofilms were either nonantibiotic exposed or previously exposed to ciprofloxacin before disaggregation and subsequent challenge with ciprofloxacin. Viable counts showed that late stationary phase cells were tolerant to ciprofloxacin over 24 h exposure, while all other populations presented a biphasic killing pattern. In contrast, the metabolic activity of planktonic and biofilm-derived cells remained similar to controls during the initial 6 h of ciprofloxacin exposure, despite a significant reduction in viable cell numbers. A similar effect was observed when assessing the postantibiotic effect of 1 h ciprofloxacin exposure. Thus, although cell reduction occurred, the metabolic status of the cells remained unchanged. The recovery of disaggregated biofilm cells previously exposed to ciprofloxacin was significantly quicker than naïve biofilm cells, and this latter population's recovery was significantly slower than all planktonic populations. Results from this work have implications for our understanding of biofilm-related infections and their resilience to antimicrobial treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: Removal of biofilms from surfaces and infection sites via disaggregation and induction of dispersion may reverse their antibiotic tolerant state. However, little is known of the recovery of the cells upon disaggregation from biofilms. Driven by this gap in knowledge we quantified the effect of ciprofloxacin on disaggregated biofilms of Pseudomonas aeruginosa, including those previously exposed to ciprofloxacin. Our results provide further insight into bacterial resilience, regrowth, and antimicrobial efficacy, as reduction in cell viability does not directly correlate with the metabolic activity of bacteria at the time of the exposure to antimicrobials. Thus, despite a perceived reduction in viability, the potential for cell persistence and regrowth remains and recovery is quicker upon subsequent exposure to antimicrobial, supporting the increase in resilience and recurrence of infections.
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Affiliation(s)
- C N H Marques
- Department of Biological Sciences, Binghamton University, Binghamton, NY, USA.,Binghamton Biofilm Research Center (BBRC), Binghamton University, Binghamton, NY, USA
| | - S M Nelson
- Department of Applied Sciences, Faculty of Health and Applied Sciences, University of the West of England, Bristol, UK
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26
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Heins AL, Lundin L, Nunes I, Gernaey KV, Sørensen SJ, Lantz AE. The effect of acetate on population heterogeneity in different cellular characteristics of Escherichia coli in aerobic batch cultures. Biotechnol Prog 2019; 35:e2796. [PMID: 30816011 DOI: 10.1002/btpr.2796] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 01/07/2019] [Accepted: 02/22/2019] [Indexed: 01/14/2023]
Abstract
Acetate as the major by-product in industrial-scale bioprocesses with Escherichia coli is found to decrease process efficiency as well as to be toxic to cells, which has several effects like a significant induction of cellular stress responses. However, the underlying phenomena are poorly explored. Therefore, we studied time-resolved population heterogeneity of the E. coli growth reporter strain MG1655/pGS20PrrnBGFPAAV expressing destabilized green fluorescent protein during batch growth on acetate and glucose as sole carbon sources. Additionally, we applied five fluorescent stains targeting different cellular properties (viability as well as metabolic and respiratory activity). Quantitative analysis of flow cytometry data verified that bacterial populations in the bioreactor are more heterogeneous in growth as well as stronger metabolically challenged during growth on acetate as sole carbon source, compared to growth on glucose or acetate after diauxic shift. Interestingly, with acetate as sole carbon source, significant subpopulations were found with some cells that seem to be more robust than the rest of the population. In conclusion, following batch cultures population heterogeneity was evident in all measured parameters. Our approach enabled a deeper study of heterogeneity during growth on the favored substrate glucose as well as on the toxic by-product acetate. Using a combination of activity fluorescent dyes proved to be an accurate and fast alternative as well as a supplement to the use of a reporter strain. However, the choice of combination of stains should be well considered depending on which population traits to aim for.
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Affiliation(s)
- Anna-Lena Heins
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kongens Lyngby, Denmark.,Institute of Biochemical Engineering, Technical University of Munich, Garching, Germany
| | - Luisa Lundin
- Department of Biology, Section of Microbiology, University of Copenhagen, Copenhagen, Denmark.,Division of Scientific Support, Becton-Dickison biosciences, Erembodegem, Belgium
| | - Inês Nunes
- Department of Biology, Section of Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Krist V Gernaey
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Søren J Sørensen
- Department of Biology, Section of Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Anna Eliasson Lantz
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kongens Lyngby, Denmark
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27
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Kamarudheen N, Rao KB. Fatty acyl compounds from marine Streptomyces griseoincarnatus strain HK12 against two major bio-film forming nosocomial pathogens; an in vitro and in silico approach. Microb Pathog 2019; 127:121-130. [DOI: 10.1016/j.micpath.2018.11.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 11/28/2018] [Accepted: 11/29/2018] [Indexed: 10/27/2022]
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28
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Genetic and Transcriptomic Analyses of Ciprofloxacin-Tolerant Staphylococcus aureus Isolated by the Replica Plating Tolerance Isolation System (REPTIS). Antimicrob Agents Chemother 2019; 63:AAC.02019-18. [PMID: 30509938 DOI: 10.1128/aac.02019-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/21/2018] [Indexed: 12/31/2022] Open
Abstract
We developed a simple, efficient, and cost-effective method, named the replica plating tolerance isolation system (REPTIS), to detect the antibiotic tolerance potential of a bacterial strain. This method can also be used to quantify the antibiotic-tolerant subpopulation in a susceptible population. Using REPTIS, we isolated ciprofloxacin (CPFX)-tolerant mutants (mutants R2, R3, R5, and R6) carrying a total of 12 mutations in 12 different genes from methicillin-sensitive Staphylococcus aureus (MSSA) strain FDA209P. Each mutant carried multiple mutations, while few strains shared the same mutation. The R2 strain carried a nonsense mutation in the stress-mediating gene, relA Additionally, two strains carried the same point mutation in the leuS gene, encoding leucyl-tRNA synthetase. Furthermore, RNA sequencing of the R strains showed a common upregulation of relA Overall, transcriptome analysis showed downregulation of genes related to translation; carbohydrate, fat, and energy metabolism; nucleotide synthesis; and upregulation of amino acid biosynthesis and transportation genes in R2, R3, and R6, similar to the findings observed for the FDA209P strain treated with mupirocin (MUP0.03). However, R5 showed a unique transcription pattern that differed from that of MUP0.03. REPTIS is a unique and convenient method for quantifying the level of tolerance of a clinical isolate. Genomic and transcriptomic analyses of R strains demonstrated that CPFX tolerance in these S. aureus mutants occurs via at least two distinct mechanisms, one of which is similar to that which occurs with mupirocin treatment.
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29
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Patkari M, Kumbhar C, Nag A, Mehra S. Distinct transcriptomic response of S. coelicolor to ciprofloxacin in a nutrient-rich environment. Appl Microbiol Biotechnol 2018; 102:10623-10643. [PMID: 30327831 DOI: 10.1007/s00253-018-9398-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 09/13/2018] [Accepted: 09/14/2018] [Indexed: 02/07/2023]
Abstract
With the rising threat of anti-microbial resistance (AMR), there is an urgent need to enhance efficacy of existing antibiotics. Understanding the myriad mechanisms through which bacteria evade these drugs would be of immense value to designing novel strategies against them. Streptomyces coelicolor A3(2) M145 belongs to the actinomyctes species that are responsible for more than two-thirds of antibiotics. This group of bacteria therefore encodes for various mechanisms that can resist both endogenous and non-endogenous antibiotics. In an earlier study, we had studied the transcriptomic response of these bacteria to ciprofloxacin, when cultured in a minimal media. In this work, we investigate why the minimum inhibitory concentration of the drug increases by fourfold when the bacteria are grown in a nutrient-rich media. Through transcriptomic, biochemical, and microscopic studies, we show that S. coelicolor responds to ciprofloxacin in a concentration-dependent manner. While, sub-inhibitory concentration of the drug primarily causes oxidative stress, the inhibitory concentration of ciprofloxacin evokes a more severe genome-wide response in the cell, which ranges from the familiar upregulation of the SOS response and DNA repair pathways to the widespread alterations in the central metabolism pathway to accommodate the increased needs of nucleotides and other precursors. Further, the upregulation of peptidoglycan synthesis genes, along with microscopy images, suggest alterations in the cell morphology to increase fitness of the bacteria during the antibiotic stress. The data also points to the enhanced efflux activity in cells cultured in rich media that contributes significantly towards reducing intracellular drug concentration and thus promotes survival.
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Affiliation(s)
- Minal Patkari
- Department of Chemical Engineering, IIT Bombay, Powai, 400076, India
- Department of Civil and Environmental Engineering, University of North Carolina at Charlotte, Charlotte, NC, USA
| | | | - Ankita Nag
- Department of Chemical Engineering, IIT Bombay, Powai, 400076, India
| | - Sarika Mehra
- Department of Chemical Engineering, IIT Bombay, Powai, 400076, India.
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30
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Khandekar S, Liebens V, Fauvart M, Tulkens PM, Michiels J, Van Bambeke F. The Putative De- N-acetylase DnpA Contributes to Intracellular and Biofilm-Associated Persistence of Pseudomonas aeruginosa Exposed to Fluoroquinolones. Front Microbiol 2018; 9:1455. [PMID: 30042739 PMCID: PMC6048251 DOI: 10.3389/fmicb.2018.01455] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 06/12/2018] [Indexed: 11/30/2022] Open
Abstract
Persisters are the fraction of antibiotic-exposed bacteria transiently refractory to killing and are recognized as a cause of antibiotic treatment failure. The putative de-N-acetylase DnpA increases persister levels in Pseudomonas aeruginosa upon exposure to fluoroquinolones in broth. In this study the wild-type PAO1 and its dnpA insertion mutant (dnpA::Tn) were used in parallel and compared for their capacity to generate persisters in broth (surviving fraction after exposure to high antibiotic concentrations) and their susceptibility to antibiotics in models of intracellular infection of THP-1 monocytes and of biofilms grown in microtiter plates. Multiplication in monocytes was evaluated by fluorescence dilution of GFP (expressed under the control of an inducible promoter) using flow cytometry. Gene expression was measured by quantitative RT-PCR. When exposed to fluoroquinolones (ciprofloxacin or levofloxacin) but not to meropenem or amikacin, the dnpA::Tn mutant showed a 3- to 10-fold lower persister fraction in broth. In infected monocytes, fluoroquinolones (but not the other antibiotics) were more effective (difference in Emax: 1.5 log cfu) against the dnpA::Tn mutant than against the wild-type PAO1. Dividing intracellular bacteria were more frequently seen (1.5 to 1.9-fold) with the fluoroquinolone-exposed dnpA::Tn mutant than with its parental strain. Fluoroquinolones (but not the other antibiotics) were also 3-fold more potent to prevent biofilm formation by the dnpA::Tn mutant than by PAO1 as well as to act upon biofilms (1–3 days of maturity) formed by the mutant than by the parental strain. Fluoroquinolones induced the expression of gyrA (4.5–7 fold) and mexX (3.6–5.4 fold) in the parental strain but to a lower extent (3–4-fold for gyrA and 1.8–2.8-fold for mexX, respectively) in the dnpA::Tn mutant. Thus, our data show that a dnpA insertion mutant of P. aeruginosa is more receptive to fluoroquinolone antibacterial effects than its parental strain in infected monocytes or in biofilms. The mechanism of this higher responsiveness could involve a reduced overexpression of the fluoroquinolone target.
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Affiliation(s)
- Shaunak Khandekar
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Veerle Liebens
- Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium
| | - Maarten Fauvart
- Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.,Center for Microbiology, Vlaams Instituut voor Biotechnologie, Leuven, Belgium.,imec, Leuven, Belgium
| | - Paul M Tulkens
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Jan Michiels
- Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium.,Center for Microbiology, Vlaams Instituut voor Biotechnologie, Leuven, Belgium
| | - Françoise Van Bambeke
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
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31
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Reserve Flux Capacity in the Pentose Phosphate Pathway Enables Escherichia coli's Rapid Response to Oxidative Stress. Cell Syst 2018; 6:569-578.e7. [PMID: 29753645 DOI: 10.1016/j.cels.2018.04.009] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 01/19/2018] [Accepted: 04/10/2018] [Indexed: 01/01/2023]
Abstract
To counteract oxidative stress and reactive oxygen species (ROS), bacteria evolved various mechanisms, primarily reducing ROS through antioxidant systems that utilize cofactor NADPH. Cells must stabilize NADPH levels by increasing flux through replenishing metabolic pathways like pentose phosphate (PP) pathway. Here, we investigate the mechanism enabling the rapid increase in NADPH supply by exposing Escherichia coli to hydrogen peroxide and quantifying the immediate metabolite dynamics. To systematically infer active regulatory interactions governing this response, we evaluated ensembles of kinetic models of glycolysis and PP pathway, each with different regulation mechanisms. Besides the known inactivation of glyceraldehyde 3-phosphate dehydrogenase by ROS, we reveal the important allosteric inhibition of the first PP pathway enzyme by NADPH. This NADPH feedback inhibition maintains a below maximum-capacity PP pathway flux under non-stress conditions. Relieving this inhibition instantly increases PP pathway flux upon oxidative stress. We demonstrate that reducing cells' capacity to rapidly reroute their flux through the PP pathway increases their oxidative stress sensitivity.
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32
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Ribera A, Soldevila L, Rigo-Bonnin R, Tubau F, Padullés A, Gómez-Junyent J, Ariza J, Murillo O. Beta-lactams in continuous infusion for Gram-negative bacilli osteoarticular infections: an easy method for clinical use. Infection 2018; 46:239-244. [PMID: 29363049 DOI: 10.1007/s15010-018-1116-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 01/16/2018] [Indexed: 12/16/2022]
Abstract
Continuous infusion (CI) of beta-lactams could optimize their pharmacokinetic/pharmacodynamic indices, especially in difficult-to-treat infections. PURPOSE To validate an easy-to-use method to guide beta-lactams dosage in CI (formula). METHODS A retrospective analysis was conducted of a prospectively collected cohort (n = 24 patients) with osteoarticular infections caused by Gram-negative bacilli (GNB) managed with beta-lactams in CI. Beta-lactams dose was calculated using a described formula (daily dose = 24 h × beta-lactam clearance × target "steady-state" concentration) to achieve concentrations above the MIC. We correlated the predicted concentration (Cpred = daily dose/24 h × beta-lactam clearance) with the patient's observed concentration (Cobs) measured by UPLC-MS/MS (Spearman's coefficient). RESULTS The most frequent microorganism treated was P. aeruginosa (21 cases; 9 MDR). Beta-lactams in CI were ceftazidime (n = 14), aztreonam (7), and piperacillin/tazobactam (3), mainly used in combination (12 with colistin, 5 with ciprofloxacin) and administered without notable side effects. The plasma Cobs was higher overall than Cpred; the Spearman correlation between both concentrations was rho = 0.6 (IC 95%: 0.2-0.8) for all beta-lactams, and rho = 0.8 (IC 95%: 0.4-1) for those treated with ceftazidime. CONCLUSIONS The formula may be useful in clinical practice for planning the initial dosage of beta-lactams in CI, while we await a systematic therapeutic drug monitoring. The use of beta-lactams in CI was safe.
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Affiliation(s)
- Alba Ribera
- Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain
| | - Laura Soldevila
- Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain
| | - Raul Rigo-Bonnin
- Clinical Laboratory Department, IDIBELL-Hospital Universitari de Bellvitge, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain
| | - Fe Tubau
- Microbiology Department, IDIBELL-Hospital Universitari de Bellvitge, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.,Ciber de Enfermedades Respiratorias ISCIII, Madrid, Spain
| | - Ariadna Padullés
- Pharmacy Department, IDIBELL-Hospital Universitari de Bellvitge, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain
| | - Joan Gómez-Junyent
- Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain
| | - Javier Ariza
- Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain
| | - Oscar Murillo
- Infectious Diseases Department, IDIBELL-Hospital Universitari de Bellvitge, Feixa Llarga s/n, Hospitalet de Llobregat, 08907, Barcelona, Spain.
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33
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Bragg RR, Meyburgh CM, Lee JY, Coetzee M. Potential Treatment Options in a Post-antibiotic Era. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1052:51-61. [DOI: 10.1007/978-981-10-7572-8_5] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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34
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Leow-Dyke SF, Rooney P, Kearney JN. The efficacy and sterilisation of human decellularised dermal allografts with combinations of cupric ions and hydrogen peroxide. Cell Tissue Bank 2017; 18:561-572. [PMID: 28952000 DOI: 10.1007/s10561-017-9660-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 09/15/2017] [Indexed: 10/18/2022]
Abstract
Decellularised tissue allografts have been used in reconstructive surgical applications and transplantation for many years. Some of the current methods of sterilisation have a detrimental effect on the tissue graft structure and function. The anti-microbial activity of cupric ions and hydrogen peroxide (H2O2) are well known however their combined application is not currently utilised as a decontamination agent in the tissue banking world sector. The aim of this study was to determine the combined concentrations of copper chloride (CuCl2) and H2O2 that have the optimal bactericidal and sporicidal activity on decellularised (dCELL) human dermis. The first part of this study established the decimal reduction time (D-value) of CuCl2 (0.1 mg/L and 1 mg/L) together with H2O2 (0.01, 0.1, 0.5 and 1%) for Staphylococcus epidermidis, Escherichia coli and Bacillus subtilis spores. The second part of this study identified the most effective CuCl2 and H2O2 concentration that decontaminated dCELL human dermis inoculated with these pathogens. Of all the concentrations tested, 0.1 mg/L CuCl2 in combination with 1% H2O2 had the shortest D-value; S. epidermidis D = 3.15 min, E. coli D = 2.62 min and B. subtilis spores D = 18.05 min. However when adsorbed onto dCELL dermis, S. epidermidis and E. coli were more susceptible to 1 mg/L CuCl2 together with 0.5% H2O2. These studies show promise of CuCl2-H2O2 formulations as potential sterilants for decellularised dermal allografts.
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Affiliation(s)
- S F Leow-Dyke
- NHS Blood and Transplant, Tissue Services R&D, Liverpool, UK. .,Public Health England, Manchester Medical Microbiology Partnership, Manchester, UK.
| | - P Rooney
- NHS Blood and Transplant, Tissue Services R&D, Liverpool, UK
| | - J N Kearney
- NHS Blood and Transplant, Tissue Services R&D, Liverpool, UK
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35
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Feng Y, Bakker RT, van Hest RM, Hodiamont CJ, Brul S, Schultsz C, ter Kuile BH. Optimization of therapy against Pseudomonas aeruginosa with ceftazidime and meropenem using chemostats as model for infections. FEMS Microbiol Lett 2017; 364:3906681. [DOI: 10.1093/femsle/fnx142] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 06/28/2017] [Indexed: 12/24/2022] Open
Abstract
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that can cause life-threatening infections in patients admitted to intensive care units. Resistance rapidly develops against two drugs of choice: ceftazidime and meropenem. Several therapeutic protocols were compared for reduction in viable cells and limiting development of resistance. Chemostat cultures were exposed to antibiotic concentrations measured in the blood of patients at low (5th percentile), medium (50th percentile) or high (95th percentile) levels in several therapy protocols to simulate therapy. Cultures exposed to ceftazidime recovered after 1 day at low, 2 days at medium and 3 days at high concentrations and developed corresponding levels of resistance. Patterns were very similar for meropenem except that recovery was delayed. Fluctuating levels and intermittent treatment achieved similar reduction of cell numbers at lower resistance costs. Treatment alternating ceftazidime and meropenem reduced cell numbers more than monotherapy, while strongly limiting resistance. Combination therapy was even more effective in both respects. Therapeutic goals are best reached with least risk of resistance when ceftazidime and meropenem are used in combination or alternating, at the highest concentrations the patient can endure. Monotherapy should also apply the highest concentration that is safe for the shortest time that achieves treatment objectives.
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Affiliation(s)
- Yanfang Feng
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, 1098 XH Amsterdam, the Netherlands
| | - Roosmarijn T Bakker
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, 1098 XH Amsterdam, the Netherlands
| | - Reinier M van Hest
- Department of Hospital Pharmacy & Clinical Pharmacology, Academic Medical Center, Amsterdam 1105AZ, the Netherlands
| | - Caspar J Hodiamont
- Department of Medical Microbiology, Academic Medical Center, Amsterdam 1105AZ, the Netherlands
| | - Stanley Brul
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, 1098 XH Amsterdam, the Netherlands
| | - Constance Schultsz
- Department of Medical Microbiology, Academic Medical Center, Amsterdam 1105AZ, the Netherlands
- Department of Global Health-Amsterdam Institute for Global Health and Development, Academic Medical Center, Amsterdam 1105AZ, the Netherlands
| | - Benno H ter Kuile
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute of Life Sciences, University of Amsterdam, 1098 XH Amsterdam, the Netherlands
- Office for Risk Assessment and Research Coordination Netherlands Food and Consumer Product Safety Authority, Utrecht 3511GG, the Netherlands
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36
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Zapotoczna M, Boksmati N, Donohue S, Bahtiar B, Boland A, Somali HA, Cox A, Humphreys H, O'Gara JP, Brennan M, O'Neill E. Novel anti-staphylococcal and anti-biofilm properties of two anti-malarial compounds: MMV665953 {1-(3-chloro-4-fluorophenyl)-3-(3,4-dichlorophenyl)urea} and MMV665807 {5-chloro-2-hydroxy-N-[3-(trifluoromethyl)phenyl]benzamide}. J Med Microbiol 2017; 66:377-387. [PMID: 28327271 DOI: 10.1099/jmm.0.000446] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
PURPOSE The treatment of device-related infections is challenging and current anti-microbial compounds have poor anti-biofilm activity. We aimed to identify and characterize novel compounds effective in the eradication of Staphylococcus aureus biofilms. METHODOLOGY Two novel compounds, MMV665953 {1-(3-chloro-4-fluorophenyl)-3-(3,4-dichlorophenyl)urea} and MMV665807{5-chloro-2-hydroxy-N-[3-(trifluoromethyl)phenyl]benzamide}, effective in killing S. aureus biofilms, were identified by screening of the open access 'malaria box' chemical library. The minimum bactericidal concentrations, half-maximal inhibition concentration (IC50) values and minimal biofilm killing concentrations effective in the killing of biofilm were determined against meticillin-resistant S. aureus and meticillin-sensitive S. aureus. Fibrin-embedded biofilms were grown under in vivo-relevant conditions, and viability was measured using a resazurin-conversion assay and confocal microscopy. The potential for the development of resistance and cytotoxicity was also assessed. RESULTS MMV665953 and MMV665807 were bactericidal against S. aureus isolates. The IC50 against S. aureus biofilms was at 0.15-0.58 mg l-1 after 24 h treatment, whereas the concentration required to eradicate all tested biofilms was 4 mg l-1, making the compounds more bactericidal than conventional antibiotics. The cytotoxicity against human keratinocytes and primary endothelial cells was determined as IC50 7.47 and 0.18 mg l-1 for MMV665953, and as 1.895 and 0.076 mg l-1 for MMV665807. Neither compound was haemolytic nor caused platelet activation. MMV665953 and MMV665807 derivatives with reduced cytotoxicity exhibited a concomitant loss in anti-staphylococcal activity. CONCLUSION MMV665953 and MMV665807 are more bactericidal against S. aureus biofilms than currently used anti-staphylococcal antibiotics and represent a valuable structural basis for further investigation in the treatment of staphylococcal biofilm-related infections.
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Affiliation(s)
- Marta Zapotoczna
- Department of Clinical Microbiology, Education and Research Centre, Beaumont Hospital, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Nabila Boksmati
- Molecular and Cellular Therapeutics, Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Sinead Donohue
- Department of Clinical Microbiology, Education and Research Centre, Beaumont Hospital, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Baizurina Bahtiar
- Molecular and Cellular Therapeutics, Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Ahmad Boland
- Molecular and Cellular Therapeutics, Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Hamzah Al Somali
- Molecular and Cellular Therapeutics, Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Alysia Cox
- Molecular and Cellular Therapeutics, Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Hilary Humphreys
- Department of Clinical Microbiology, Education and Research Centre, Beaumont Hospital, Royal College of Surgeons in Ireland, Dublin, Ireland.,Department of Microbiology, Beaumont Hospital, Dublin, Ireland
| | - James P O'Gara
- Department of Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Marian Brennan
- Molecular and Cellular Therapeutics, Irish Centre for Vascular Biology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Eoghan O'Neill
- Department of Microbiology, Connolly Hospital, Dublin, Ireland.,Department of Clinical Microbiology, Education and Research Centre, Beaumont Hospital, Royal College of Surgeons in Ireland, Dublin, Ireland
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37
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Lukačišinová M, Bollenbach T. Toward a quantitative understanding of antibiotic resistance evolution. Curr Opin Biotechnol 2017; 46:90-97. [PMID: 28292709 DOI: 10.1016/j.copbio.2017.02.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 02/20/2017] [Accepted: 02/21/2017] [Indexed: 01/27/2023]
Abstract
The rising prevalence of antibiotic resistant bacteria is an increasingly serious public health challenge. To address this problem, recent work ranging from clinical studies to theoretical modeling has provided valuable insights into the mechanisms of resistance, its emergence and spread, and ways to counteract it. A deeper understanding of the underlying dynamics of resistance evolution will require a combination of experimental and theoretical expertise from different disciplines and new technology for studying evolution in the laboratory. Here, we review recent advances in the quantitative understanding of the mechanisms and evolution of antibiotic resistance. We focus on key theoretical concepts and new technology that enables well-controlled experiments. We further highlight key challenges that can be met in the near future to ultimately develop effective strategies for combating resistance.
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Affiliation(s)
| | - Tobias Bollenbach
- IST Austria, Am Campus 1, A-3400 Klosterneuburg, Austria; University of Cologne, Zülpicher Str. 47a, D-50674 Cologne, Germany.
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38
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Zampieri M, Enke T, Chubukov V, Ricci V, Piddock L, Sauer U. Metabolic constraints on the evolution of antibiotic resistance. Mol Syst Biol 2017; 13:917. [PMID: 28265005 PMCID: PMC5371735 DOI: 10.15252/msb.20167028] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Despite our continuous improvement in understanding antibiotic resistance, the interplay between natural selection of resistance mutations and the environment remains unclear. To investigate the role of bacterial metabolism in constraining the evolution of antibiotic resistance, we evolved Escherichia coli growing on glycolytic or gluconeogenic carbon sources to the selective pressure of three different antibiotics. Profiling more than 500 intracellular and extracellular putative metabolites in 190 evolved populations revealed that carbon and energy metabolism strongly constrained the evolutionary trajectories, both in terms of speed and mode of resistance acquisition. To interpret and explore the space of metabolome changes, we developed a novel constraint‐based modeling approach using the concept of shadow prices. This analysis, together with genome resequencing of resistant populations, identified condition‐dependent compensatory mechanisms of antibiotic resistance, such as the shift from respiratory to fermentative metabolism of glucose upon overexpression of efflux pumps. Moreover, metabolome‐based predictions revealed emerging weaknesses in resistant strains, such as the hypersensitivity to fosfomycin of ampicillin‐resistant strains. Overall, resolving metabolic adaptation throughout antibiotic‐driven evolutionary trajectories opens new perspectives in the fight against emerging antibiotic resistance.
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Affiliation(s)
- Mattia Zampieri
- Institute of Molecular Systems Biology, ETH Zürich, Zürich, Switzerland
| | - Tim Enke
- Institute of Molecular Systems Biology, ETH Zürich, Zürich, Switzerland.,Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zürich, Zürich, Switzerland
| | - Victor Chubukov
- Institute of Molecular Systems Biology, ETH Zürich, Zürich, Switzerland
| | - Vito Ricci
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Laura Piddock
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Uwe Sauer
- Institute of Molecular Systems Biology, ETH Zürich, Zürich, Switzerland
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39
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Gorr TA. Hypometabolism as the ultimate defence in stress response: how the comparative approach helps understanding of medically relevant questions. Acta Physiol (Oxf) 2017; 219:409-440. [PMID: 27364602 DOI: 10.1111/apha.12747] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 01/28/2016] [Accepted: 06/28/2016] [Indexed: 12/22/2022]
Abstract
First conceptualized from breath-hold diving mammals, later recognized as the ultimate cell autonomous survival strategy in anoxia-tolerant vertebrates and burrowing or hibernating rodents, hypometabolism is typically recruited by resilient organisms to withstand and recover from otherwise life-threatening hazards. Through the coordinated down-regulation of biosynthetic, proliferative and electrogenic expenditures at times when little ATP can be generated, a metabolism turned 'down to the pilot light' allows the re-balancing of energy demand with supply at a greatly suppressed level in response to noxious exogenous stimuli or seasonal endogenous cues. A unifying hallmark of stress-tolerant organisms, the adaptation effectively prevents lethal depletion of ATP, thus delineating a marked contrast with susceptible species. Along with disengaged macromolecular syntheses, attenuated transmembrane ion shuttling and PO2 -conforming respiration rates, the metabolic slowdown in tolerant species usually culminates in a non-cycling, quiescent phenotype. However, such a reprogramming also occurs in leading human pathophysiologies. Ranging from microbial infections through ischaemia-driven infarcts to solid malignancies, cells involved in these disorders may again invoke hypometabolism to endure conditions non-permissive for growth. At the same time, their reduced activities underlie the frequent development of a general resistance to therapeutic interventions. On the other hand, a controlled induction of hypometabolic and/or hypothermic states by pharmacological means has recently stimulated intense research aimed at improved organ preservation and patient survival in situations requiring acutely administered critical care. The current review article therefore presents an up-to-date survey of concepts and applications of a coordinated and reversibly down-regulated metabolic rate as the ultimate defence in stress responses.
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Affiliation(s)
- T. A. Gorr
- Institute of Veterinary Physiology; Vetsuisse Faculty; University of Zurich; Zurich Switzerland
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40
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In Vitro Tolerance of Drug-Naive Staphylococcus aureus Strain FDA209P to Vancomycin. Antimicrob Agents Chemother 2017; 61:AAC.01154-16. [PMID: 27855063 PMCID: PMC5278750 DOI: 10.1128/aac.01154-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 11/03/2016] [Indexed: 12/26/2022] Open
Abstract
The mechanisms underlying bacterial tolerance to antibiotics are unclear. A possible adaptation strategy was explored by exposure of drug-naive methicillin-susceptible Staphylococcus aureus strain FDA209P to vancomycin in vitro. Strains surviving vancomycin treatment (vancomycin survivor strains), which appeared after 96 h of exposure, were slow-growing derivatives of the parent strain. Although the vancomycin MICs for the survivor strains were within the susceptible range, the cytokilling effects of vancomycin at 20-fold the MIC were significantly lower for the survivor strains than for the parent strain. Whole-genome sequencing demonstrated that ileS, encoding isoleucyl-tRNA synthetase (IleRS), was mutated in two of the three vancomycin survivor strains. The IleRS Y723H mutation is located close to the isoleucyl-tRNA contact site and potentially affects the affinity of IleRS binding to isoleucyl-tRNA, thereby inhibiting protein synthesis and leading to vancomycin tolerance. Introduction of the mutation encoding IleRS Y723H into FDA209P by allelic replacement successfully transferred the vancomycin tolerance phenotype. We have identified mutation of ileS to be one of the bona fide genetic events leading to the acquisition of vancomycin tolerance in S. aureus, potentially acting via inhibition of the function of IleRS.
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Bruchmann J, Pini I, Gill TS, Schwartz T, Levkin PA. Patterned SLIPS for the Formation of Arrays of Biofilm Microclusters with Defined Geometries. Adv Healthc Mater 2017; 6. [PMID: 27879061 DOI: 10.1002/adhm.201601082] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 10/21/2016] [Indexed: 11/06/2022]
Abstract
Biofilms represent an immense problem in medicine due to their strong drug-resistant properties and inherent stress-response activities. Due to the inhomogeneous and very complex architectures of large biofilm aggregates, biofilm studies often suffer from low reproducibility. In this study, an approach to form arrays of homogeneous biofilm microclusters with defined 2D geometries is presented. The method is based on the formation of water-infused hydrophilic porous polymer areas with precise geometries separated by "slippery" lubricant-infused porous surface (SLIPS). Due to the SLIPS' biofilm repellent properties, multiple identical 3D biofilm clusters are formed in the hydrophilic patches that can be used for biofilm screening. Formation of biofilm microcluster arrays of different bacterial strains of Pseudomonas aeruginosa on the SLIPS micropatterns is investigated. Critical parameters influencing minimal adhesive regions for biofilm attachment and minimal SLIPS dimensions to avoid biofilm adhesion are studied. The ability to produce arrays of biofilm microclusters with highly uniform, well-defined shapes opens an opportunity to study interactions of biofilms with various medically relevant factors with a better reproducibility and to investigate the complex biofilm architecture, heterogeneity, and interactions between biofilm subpopulations.
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Affiliation(s)
- Julia Bruchmann
- Institute of Functional Interfaces; Karlsruhe Institute of Technology; Hermann-von-Helmholtz Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Ivana Pini
- Institute of Toxicology and Genetics; Karlsruhe Institute of Technology; Hermann-von-Helmholtz Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Tejeshwar S. Gill
- Institute of Toxicology and Genetics; Karlsruhe Institute of Technology; Hermann-von-Helmholtz Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Thomas Schwartz
- Institute of Functional Interfaces; Karlsruhe Institute of Technology; Hermann-von-Helmholtz Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Pavel A. Levkin
- Institute of Toxicology and Genetics; Karlsruhe Institute of Technology; Hermann-von-Helmholtz Platz 1 76344 Eggenstein-Leopoldshafen Germany
- Institute of Organic Chemistry; Karlsruhe Institute of Technology; 76131 Karlsruhe Germany
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42
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Allas UL, Toom L, Selyutina A, Mäeorg U, Medina R, Merits A, Rinken A, Hauryliuk V, Kaldalu N, Tenson T. Antibacterial activity of the nitrovinylfuran G1 (Furvina) and its conversion products. Sci Rep 2016; 6:36844. [PMID: 27830730 PMCID: PMC5103279 DOI: 10.1038/srep36844] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 10/20/2016] [Indexed: 11/24/2022] Open
Abstract
2-Bromo-5-(2-bromo-2-nitrovinyl)furan (G1 or Furvina) is an antimicrobial with a direct reactivity against thiol groups. It is active against Gram-positive and Gram-negative bacteria, yeasts and filamentous fungi. By reacting with thiol groups it causes direct damage to proteins but, as a result, is very short-living and interconverts into an array of reaction products. Our aim was to characterize thiol reactivity of G1 and its conversion products and establish how much of antimicrobial and cytotoxic effects are due to the primary activity of G1 and how much can be attributed to its reaction products. Stability of G1 in growth media as well as its conversion in the presence of thiols was characterized. The structures of G1 decomposition products were determined using NMR and mass-spectroscopy. Concentration- and time-dependent killing curves showed that G1 is bacteriostatic for Escherichia coli at the concentration of 16 μg/ml and bactericidal at 32 μg/ml. However, G1 is inefficient against non-growing E. coli. Addition of cysteine to medium reduces the antimicrobial potency of G1. Nevertheless, the reaction products of G1 and cysteine enabled prolonged antimicrobial action of the drug. Therefore, the activity of 2-bromo-5-(2-bromo-2-nitrovinyl)furan is a sum of its immediate reactivity and the antibacterial effects of the conversion products.
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Affiliation(s)
- U Lar Allas
- University of Tartu, Institute of Technology, Nooruse 1, Tartu 50411, Estonia
| | - Lauri Toom
- University of Tartu, Institute of Technology, Nooruse 1, Tartu 50411, Estonia
| | - Anastasia Selyutina
- University of Tartu, Institute of Technology, Nooruse 1, Tartu 50411, Estonia
| | - Uno Mäeorg
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia
| | - Ricardo Medina
- Universidad Central "Marta Abreu" de Las Villas, Santa Clara, Cuba
| | - Andres Merits
- University of Tartu, Institute of Technology, Nooruse 1, Tartu 50411, Estonia
| | - Ago Rinken
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia
| | - Vasili Hauryliuk
- University of Tartu, Institute of Technology, Nooruse 1, Tartu 50411, Estonia.,Department of Molecular Biology, Umeå University, Umeå, Sweden.,Laboratory for Molecular Infection Medicine Sweden, Umeå University, Umeå, Sweden
| | - Niilo Kaldalu
- University of Tartu, Institute of Technology, Nooruse 1, Tartu 50411, Estonia
| | - Tanel Tenson
- University of Tartu, Institute of Technology, Nooruse 1, Tartu 50411, Estonia
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Fiaux E, Titecat M, Robineau O, Lora-Tamayo J, El Samad Y, Etienne M, Frebourg N, Blondiaux N, Brunschweiler B, Dujardin F, Beltrand E, Loiez C, Cattoir V, Canarelli JP, Hulet C, Valette M, Nguyen S, Caron F, Migaud H, Senneville E. Outcome of patients with streptococcal prosthetic joint infections with special reference to rifampicin combinations. BMC Infect Dis 2016; 16:568. [PMID: 27737642 PMCID: PMC5064929 DOI: 10.1186/s12879-016-1889-0] [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: 11/22/2015] [Accepted: 10/01/2016] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Outcome of patients with streptococcal prosthetic joint infections (PJIs) is not well known. METHODS We performed a retrospective multicenter cohort study that involved patients with total hip/knee prosthetic joint (THP/TKP) infections due to Streptococcus spp. from 2001 through 2009. RESULTS Ninety-five streptococcal PJI episodes (50 THP and 45 TKP) in 87 patients of mean age 69.1 ± 13.7 years met the inclusion criteria. In all, 55 out of 95 cases (57.9 %) were treated with debridement and retention of the infected implants with antibiotic therapy (DAIR). Rifampicin-combinations, including with levofloxacin, were used in 52 (54.7 %) and 28 (29.5 %) cases, respectively. After a mean follow-up period of 895 days (IQR: 395-1649), the remission rate was 70.5 % (67/95). Patients with PJIs due to S. agalactiae failed in the same proportion as in the other patients (10/37 (27.1 %) versus 19/58 (32.7 %); p = .55). In the univariate analysis, antibiotic monotherapy, DAIR, antibiotic treatments other than rifampicin-combinations, and TKP were all associated with a worse outcome. The only independent variable significantly associated with the patients' outcomes was the location of the prosthesis (i.e., hip versus knee) (OR = 0.19; 95 % CI 0.04-0.93; p value 0.04). CONCLUSIONS The prognosis of streptococcal PJIs may not be as good as previously reported, especially for patients with an infected total knee arthroplasty. Rifampicin combinations, especially with levofloxacin, appear to be suitable antibiotic regimens for these patients.
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Affiliation(s)
- E Fiaux
- Infectious Diseases Department, University Hospital of Rouen, Rouen, France
| | - M Titecat
- Laboratory of Microbiology, University Hospital of Lille, Lille, France
| | - O Robineau
- Infectious Diseases Department, Gustave Dron Hospital of Tourcoing, 135 rue du Président Coty, 59200, Tourcoing, France
| | - J Lora-Tamayo
- Unit of Infectious Diseases Hospital 12 de Octubre of Madrid, Madrid, Spain
| | - Y El Samad
- Infectious Diseases Department, University Hospital of Amiens, Amiens, France
| | - M Etienne
- Infectious Diseases Department, University Hospital of Rouen, Rouen, France
| | - N Frebourg
- Laboratory of Microbiology, University Hospital of Rouen, Rouen, France
| | - N Blondiaux
- Laboratory of Microbiology, Gustave Dron Hospital of Tourcoing, Tourcoing, France
| | - B Brunschweiler
- Orthopaedic Surgery Unit, University Hospital of Amiens, Amiens, France
| | - F Dujardin
- Orthopaedic Surgery Unit, University Hospital of Rouen, Rouen, France
| | - E Beltrand
- Orthopaedic Surgery Unit, Gustave Dron Hospital of Tourcoing, Tourcoing, France
| | - C Loiez
- Laboratory of Microbiology, University Hospital of Lille, Lille, France
| | - V Cattoir
- Laboratory of Microbiology, University Hospital of Caen, Caen, France
| | - J P Canarelli
- Orthopaedic Surgery Unit, University Hospital of Amiens, Amiens, France
| | - C Hulet
- Orthopaedic Surgery Unit, University Hospital of Caen, Caen, France
| | - M Valette
- Infectious Diseases Department, Gustave Dron Hospital of Tourcoing, 135 rue du Président Coty, 59200, Tourcoing, France
| | - S Nguyen
- Infectious Diseases Department, Gustave Dron Hospital of Tourcoing, 135 rue du Président Coty, 59200, Tourcoing, France
| | - F Caron
- Infectious Diseases Department, University Hospital of Rouen, Rouen, France
| | - H Migaud
- Orthopaedic Surgery Unit, University Hospital of Lille, Lille, France
| | - E Senneville
- Infectious Diseases Department, Gustave Dron Hospital of Tourcoing, 135 rue du Président Coty, 59200, Tourcoing, France. .,French Reference Center for Osteo-Articular Infections (CRIOAC Lille-Tourcoing), Faculty Hospital of Lille, Lille, France.
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44
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Amin Yavari S, Loozen L, Paganelli FL, Bakhshandeh S, Lietaert K, Groot JA, Fluit AC, Boel CHE, Alblas J, Vogely HC, Weinans H, Zadpoor AA. Antibacterial Behavior of Additively Manufactured Porous Titanium with Nanotubular Surfaces Releasing Silver Ions. ACS APPLIED MATERIALS & INTERFACES 2016; 8:17080-17089. [PMID: 27300485 DOI: 10.1021/acsami.6b03152] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Additive manufacturing (3D printing) has enabled fabrication of geometrically complex and fully interconnected porous biomaterials with huge surface areas that could be used for biofunctionalization to achieve multifunctional biomaterials. Covering the huge surface area of such porous titanium with nanotubes has been already shown to result in improved bone regeneration performance and implant fixation. In this study, we loaded TiO2 nanotubes with silver antimicrobial agents to equip them with an additional biofunctionality, i.e., antimicrobial behavior. An optimized anodizing protocol was used to create nanotubes on the entire surface area of direct metal printed porous titanium scaffolds. The nanotubes were then loaded by soaking them in three different concentrations (i.e., 0.02, 0.1, and 0.5 M) of AgNO3 solution. The antimicrobial behavior and cell viability of the developed biomaterials were assessed. As far as the early time points (i.e., up to 1 day) are concerned, the biomaterials were found to be extremely effective in preventing biofilm formation and decreasing the number of planktonic bacteria particularly for the middle and high concentrations of silver ions. Interestingly, nanotubes not loaded with antimicrobial agents also showed significantly smaller numbers of adherent bacteria at day 1, which may be attributed to the bactericidal effect of high aspect ratio nanotopographies. The specimens with the highest concentrations of antimicrobial agents adversely affected cell viability at day 1, but this effect is expected to decrease or disappear in the following days as the rate of release of silver ions was observed to markedly decrease within the next few days. The antimicrobial effects of the biomaterials, particularly the ones with the middle and high concentrations of antimicrobial agents, continued until 2 weeks. The potency of the developed biomaterials in decreasing the number of planktonic bacteria and hindering the formation of biofilms make them promising candidates for combating peri-operative implant-associated infections.
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Affiliation(s)
- S Amin Yavari
- Department of Orthopedics, University Medical Centre Utrecht , 3584 CX Utrecht, The Netherlands
- Department of Biomechanical Engineering, Delft University of Technology , 2628 CD Delft, The Netherlands
| | - L Loozen
- Department of Orthopedics, University Medical Centre Utrecht , 3584 CX Utrecht, The Netherlands
| | - F L Paganelli
- Department of Medical Microbiology, University Medical Center Utrecht , 3584 CX Utrecht, The Netherlands
| | - S Bakhshandeh
- Department of Biomechanical Engineering, Delft University of Technology , 2628 CD Delft, The Netherlands
| | - K Lietaert
- 3D Systems-LayerWise NV, 3001 Leuven, Belgium
- Department of Materials Engineering, Katholieke Universiteit Leuven , 3000 Leuven, Belgium
| | - J A Groot
- Department of Medical Microbiology, University Medical Center Utrecht , 3584 CX Utrecht, The Netherlands
| | - A C Fluit
- Department of Medical Microbiology, University Medical Center Utrecht , 3584 CX Utrecht, The Netherlands
| | - C H E Boel
- Department of Medical Microbiology, University Medical Center Utrecht , 3584 CX Utrecht, The Netherlands
| | - J Alblas
- Department of Orthopedics, University Medical Centre Utrecht , 3584 CX Utrecht, The Netherlands
| | - H C Vogely
- Department of Orthopedics, University Medical Centre Utrecht , 3584 CX Utrecht, The Netherlands
| | - H Weinans
- Department of Orthopedics, University Medical Centre Utrecht , 3584 CX Utrecht, The Netherlands
- Department of Biomechanical Engineering, Delft University of Technology , 2628 CD Delft, The Netherlands
- Department of Rheumatology, University Medical Centre Utrecht , 3584 CX Utrecht, The Netherlands
| | - A A Zadpoor
- Department of Biomechanical Engineering, Delft University of Technology , 2628 CD Delft, The Netherlands
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Abstract
Mycobacteria grow and divide asymmetrically, creating variability in growth pole age, growth properties, and antibiotic susceptibilities. Here, we investigate the importance of growth pole age and other growth properties in determining the spectrum of responses of Mycobacterium smegmatis to challenge with rifampicin. We used a combination of live-cell microscopy and modeling to prospectively identify subpopulations with altered rifampicin susceptibility. We found two subpopulations that had increased susceptibility. At the initiation of treatment, susceptible cells were either small and at early stages of the cell cycle, or large and in later stages of their cell cycle. In contrast to this temporal window of susceptibility, tolerance was associated with factors inherited at division: long birth length and mature growth poles. Thus, rifampicin response is complex and due to a combination of differences established from both asymmetric division and the timing of treatment relative to cell birth.
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46
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McDaniel MM, Krishna N, Handagama WG, Eda S, Ganusov VV. Quantifying Limits on Replication, Death, and Quiescence of Mycobacterium tuberculosis in Mice. Front Microbiol 2016; 7:862. [PMID: 27379030 PMCID: PMC4906525 DOI: 10.3389/fmicb.2016.00862] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 05/23/2016] [Indexed: 02/02/2023] Open
Abstract
When an individual is exposed to Mycobacterium tuberculosis (Mtb) three outcomes are possible: bacterial clearance, active disease, or latent infection. It is generally believed that most individuals exposed to Mtb become latently infected and carry the mycobacteria for life. How Mtb is maintained during this latent infection remains largely unknown. During an Mtb infection in mice, there is a phase of rapid increase in bacterial numbers in the murine lungs within the first 3 weeks, and then bacterial numbers either stabilize or increase slowly over the period of many months. It has been debated whether the relatively constant numbers of bacteria in the chronic infection result from latent (dormant, quiescent), non-replicating bacteria, or whether the observed Mtb cell numbers are due to balance between rapid replication and death. A recent study of mice, infected with a Mtb strain carrying an unstable plasmid, showed that during the chronic phase, Mtb was replicating at significant rates. Using experimental data from this study and mathematical modeling we investigated the limits of the rates of bacterial replication, death, and quiescence during Mtb infection of mice. First, we found that to explain the data the rates of bacterial replication and death could not be constant and had to decrease with time since infection unless there were large changes in plasmid segregation probability over time. While a decrease in the rate of Mtb replication with time since infection was expected due to depletion of host's resources, a decrease in the Mtb death rate was counterintuitive since Mtb-specific immune response, appearing in the lungs 3–4 weeks after infection, should increase removal of bacteria. Interestingly, we found no significant correlation between estimated rates of Mtb replication and death suggesting the decline in these rates was driven by independent mechanisms. Second, we found that the data could not be explained by assuming that bacteria do not die, suggesting that some removal of bacteria from lungs of these mice had to occur even though the total bacterial counts in these mice always increased over time. Third and finally, we showed that to explain the data the majority of bacterial cells (at least ~60%) must be replicating in the chronic phase of infection further challenging widespread belief of nonreplicating Mtb in latency. Our predictions were robust to some changes in the structure of the model, for example, when the loss of plasmid-bearing cells was mainly due to high fitness cost of the plasmid. Further studies should determine if more mechanistic models for Mtb dynamics are also able to accurately explain these data.
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Affiliation(s)
- Margaret M McDaniel
- National Institute for Mathematical and Biological SynthesisKnoxville, TN, USA; Department of Biochemistry, Cellular and Molecular Biology, University of TennesseeKnoxville, TN, USA; Department of Mathematics, University of TennesseeKnoxville, TN, USA
| | - Nitin Krishna
- National Institute for Mathematical and Biological SynthesisKnoxville, TN, USA; The College at the University of ChicagoChicago, IL, USA
| | - Winode G Handagama
- National Institute for Mathematical and Biological SynthesisKnoxville, TN, USA; Departments of Chemistry and Mathematics, Maryville CollegeMaryville, TN, USA
| | - Shigetoshi Eda
- National Institute for Mathematical and Biological SynthesisKnoxville, TN, USA; Department of Forestry, Wildlife and Fisheries, University of TennesseeKnoxville, TN, USA
| | - Vitaly V Ganusov
- National Institute for Mathematical and Biological SynthesisKnoxville, TN, USA; Department of Mathematics, University of TennesseeKnoxville, TN, USA; Department of Microbiology, University of TennesseeKnoxville, TN, USA
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Roles of the glutathione- and thioredoxin-dependent systems in the Escherichia coli responses to ciprofloxacin and ampicillin. Arch Microbiol 2016; 198:913-21. [DOI: 10.1007/s00203-016-1247-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 01/13/2016] [Accepted: 05/23/2016] [Indexed: 10/21/2022]
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48
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Zhao Y, Qu D, Zhou R, Yang S, Ren H. Efficacy of forming biofilms by Pseudomonas migulae AN-1 toward in situ bioremediation of aniline-contaminated aquifer by groundwater circulation wells. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:11568-11573. [PMID: 27115704 DOI: 10.1007/s11356-016-6737-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 04/20/2016] [Indexed: 06/05/2023]
Abstract
The formation and activity of aniline-degrading biofilms developed by the psychrotrophic Pseudomonas migulae AN-1 were studied for the in situ remediation of contaminated aquifer using in-well bioreactor of groundwater circulating wells (GCWs). Biofilms grown in mineral salt medium with aniline exhibited tolerance to high concentrations of aniline. In aniline degradation rate, AN-1 biofilms exhibited slight differences compared with planktonic cells. The effectiveness and bio-implication of AN-1 biofilms in GCWs were investigated to treat aniline-contaminated aquifer. The results demonstrate that AN-1 biofilms survived the GCWs treatment process with high aniline-degrading efficiency. This system provides a novel environmentally friendly technology for the in situ bioremediation of low-volatile contaminants.
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Affiliation(s)
- Yongsheng Zhao
- Key Laboratory of Groundwater Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, 2519 Jiefang Road, Changchun, 130021, People's Republic of China
| | - Dan Qu
- Key Laboratory of Groundwater Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, 2519 Jiefang Road, Changchun, 130021, People's Republic of China
| | - Rui Zhou
- Key Laboratory of Groundwater Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, 2519 Jiefang Road, Changchun, 130021, People's Republic of China
| | - Shuai Yang
- Key Laboratory of Groundwater Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, 2519 Jiefang Road, Changchun, 130021, People's Republic of China
| | - Hejun Ren
- Key Laboratory of Groundwater Resources and Environment of the Ministry of Education, College of Environment and Resources, Jilin University, 2519 Jiefang Road, Changchun, 130021, People's Republic of China.
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Germoni LAP, Bremer PJ, Lamont IL. The effect of alginate lyase on the gentamicin resistance of Pseudomonas aeruginosa in mucoid biofilms. J Appl Microbiol 2016; 121:126-35. [PMID: 27061817 DOI: 10.1111/jam.13153] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 04/05/2016] [Accepted: 04/06/2016] [Indexed: 12/22/2022]
Abstract
AIMS Pseudomonas aeruginosa can secrete large amounts of alginate during chronic infections and this has been associated with high resistance to antibiotics. The major aim of this study was to investigate whether degradation of extracellular alginate by alginate lyase would increase the sensitivity of Ps. aeruginosa to gentamicin, an aminoglycoside antibiotic. METHODS AND RESULTS Degradation of alginate from Ps. aeruginosa was monitored using a spectrometric assay. Alginate lyase depolymerized alginate, but calcium and zinc cations at concentrations found in the cystic fibrosis lung reduced enzyme activity. Biofilms formed on agar were partially degraded by alginate lyase, but staining with crystal violet showed that the biomass of biofilms grown in liquid was not significantly affected by the enzyme. Viability testing showed that the sensitivity to gentamicin of biofilm bacteria and of bacteria released from biofilms was unaffected by alginate lyase. CONCLUSIONS Our results show that at least under the conditions used here alginate lyase does not affect gentamicin resistance of Ps. aeruginosa. SIGNIFICANCE AND IMPACT OF THE STUDY Our study indicates that alginate does not contribute to resistance to gentamicin and so does not provide support for the concept of treating patients with alginate lyase in order to increase the antibiotic sensitivity of Ps. aeruginosa.
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Affiliation(s)
- L A P Germoni
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - P J Bremer
- Department of Food Science, University of Otago, Dunedin, New Zealand
| | - I L Lamont
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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50
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Loeffler KA, Johnson TA, Burne RA, Antonelli PJ. Biofilm formation in an in vitro model of cochlear implants with removable magnets. Otolaryngol Head Neck Surg 2016; 136:583-8. [PMID: 17418256 DOI: 10.1016/j.otohns.2006.11.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2006] [Accepted: 11/01/2006] [Indexed: 11/19/2022]
Abstract
Background Cochlear implant (CI) recesses, such as the removable magnet pocket, appear to harbor more biofilm than smooth surfaces. The aim of this study was to examine the impact of removable magnets on biofilm formation in an in vitro model. Methods Silastic models were constructed to represent CIs with and without a magnet pocket and with and without a titanium blank in the pocket. CIs were exposed to a culture of a biofilm forming strain of Staphylococcus aureus. Adherence of planktonic bacteria and biofilm formation were assessed with quantitative bacterial counts and scanning electron microscopy. Results Adherent bacterial counts were significantly higher in CI models with an empty magnet pocket ( P = 0.0097). Biofilm formation was significantly lower in CI models without a magnet pocket ( P = 0.0121). Conclusions CI magnet pockets harbor bacteria that can increase biofilm development in an in vitro model.
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Affiliation(s)
- Kimberly A Loeffler
- Department of Otolaryngology, University of Florida, Gainesville, FL 32610-0264, USA
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