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Antibacterial Effects of X-ray and MRI Contrast Media: An In Vitro Pilot Study. Int J Mol Sci 2023; 24:ijms24043470. [PMID: 36834880 PMCID: PMC9966632 DOI: 10.3390/ijms24043470] [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: 01/10/2023] [Revised: 02/05/2023] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
Some radiological contrast agents have been shown to have effects on bacterial growth. In this study, the antibacterial effect and mechanism of action of iodinated X-ray contrast agents (Ultravist 370, Iopamiro 300, Telebrix Gastro 300 and Visipaque) and complexed lanthanide MRI contrast solutions (MultiHance and Dotarem) were tested against six different microorganisms. Bacteria with high and low concentrations were exposed to media containing different contrast media for various lengths of time and at pH 7.0 and 5.5. The antibacterial effect of the media was examined in further tests using agar disk diffusion analysis and the microdilution inhibition method. Bactericidal effects were found for microorganisms at low concentrations and low pH. Reductions were confirmed for Staphylococcus aureus and Escherichia coli.
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2
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Huemer M, Mairpady Shambat S, Hertegonne S, Bergada-Pijuan J, Chang CC, Pereira S, Gómez-Mejia A, Van Gestel L, Bär J, Vulin C, Pfammatter S, Stinear TP, Monk IR, Dworkin J, Zinkernagel AS. Serine-threonine phosphoregulation by PknB and Stp contributes to quiescence and antibiotic tolerance in Staphylococcus aureus. Sci Signal 2023; 16:eabj8194. [PMID: 36595572 DOI: 10.1126/scisignal.abj8194] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 12/06/2022] [Indexed: 01/05/2023]
Abstract
Staphylococcus aureus can cause infections that are often chronic and difficult to treat, even when the bacteria are not antibiotic resistant because most antibiotics act only on metabolically active cells. Subpopulations of persister cells are metabolically quiescent, a state associated with delayed growth, reduced protein synthesis, and increased tolerance to antibiotics. Serine-threonine kinases and phosphatases similar to those found in eukaryotes can fine-tune essential bacterial cellular processes, such as metabolism and stress signaling. We found that acid stress-mimicking conditions that S. aureus experiences in host tissues delayed growth, globally altered the serine and threonine phosphoproteome, and increased threonine phosphorylation of the activation loop of the serine-threonine protein kinase B (PknB). The deletion of stp, which encodes the only annotated functional serine-threonine phosphatase in S. aureus, increased the growth delay and phenotypic heterogeneity under different stress challenges, including growth in acidic conditions, the intracellular milieu of human cells, and abscesses in mice. This growth delay was associated with reduced protein translation and intracellular ATP concentrations and increased antibiotic tolerance. Using phosphopeptide enrichment and mass spectrometry-based proteomics, we identified targets of serine-threonine phosphorylation that may regulate bacterial growth and metabolism. Together, our findings highlight the importance of phosphoregulation in mediating bacterial quiescence and antibiotic tolerance and suggest that targeting PknB or Stp might offer a future therapeutic strategy to prevent persister formation during S. aureus infections.
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Affiliation(s)
- Markus Huemer
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Srikanth Mairpady Shambat
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sanne Hertegonne
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Judith Bergada-Pijuan
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Chun-Chi Chang
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sandro Pereira
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Alejandro Gómez-Mejia
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Lies Van Gestel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Julian Bär
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Clément Vulin
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Sibylle Pfammatter
- Functional Genomics Center Zurich, ETH/University of Zurich, Zurich, Switzerland
| | - Timothy P Stinear
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Ian R Monk
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Jonathan Dworkin
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Annelies S Zinkernagel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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3
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Wang Z, Li Q, Li J, Shang L, Li J, Chou S, Lyu Y, Shan A. pH-Responsive Antimicrobial Peptide with Selective Killing Activity for Bacterial Abscess Therapy. J Med Chem 2022; 65:5355-5373. [PMID: 35294199 DOI: 10.1021/acs.jmedchem.1c01485] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The unusual acidic pH of the abscess milieu is an adverse factor that decreases the therapeutic efficacy of traditional antibiotics. Moreover, avoiding both the undesired killing of commensal bacteria and the development of drug resistance remains difficult during abscess therapy. Hence, we synthesized a series of pH-responsive antimicrobial peptides equipped with efficient bacterial killing activity at pH 6.5 and inactivity at pH 7.4. Among the peptides, F5 exhibited outstanding pH-responsive antimicrobial activity and low toxicity. Fluorescence spectroscopy and electron microscopy illustrated that F5 killed bacteria via a membrane-disruptive mechanism at acidic pH values. Mouse cutaneous abscesses revealed that F5 was equipped with excellent therapeutic ability to reduce the bacterial load and cytokines without causing skin toxicity. In summary, this study reveals a strategy for selectively killing bacteria under the pathologic conditions of abscess sites while avoiding the elimination of commensal bacteria under normal physiological pH levels.
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Affiliation(s)
- Zhihua Wang
- The Laboratory of Molecular Nutrition and Immunity, Institute of Animal Nutrition, Northeast Agricultural University, Harbin 150030 P. R. China
| | - Qiuke Li
- The Laboratory of Molecular Nutrition and Immunity, Institute of Animal Nutrition, Northeast Agricultural University, Harbin 150030 P. R. China
| | - Jinze Li
- The Laboratory of Molecular Nutrition and Immunity, Institute of Animal Nutrition, Northeast Agricultural University, Harbin 150030 P. R. China
| | - Lu Shang
- The Laboratory of Molecular Nutrition and Immunity, Institute of Animal Nutrition, Northeast Agricultural University, Harbin 150030 P. R. China
| | - Jiawei Li
- The Laboratory of Molecular Nutrition and Immunity, Institute of Animal Nutrition, Northeast Agricultural University, Harbin 150030 P. R. China
| | - Shuli Chou
- The Laboratory of Molecular Nutrition and Immunity, Institute of Animal Nutrition, Northeast Agricultural University, Harbin 150030 P. R. China
| | - Yinfeng Lyu
- The Laboratory of Molecular Nutrition and Immunity, Institute of Animal Nutrition, Northeast Agricultural University, Harbin 150030 P. R. China
| | - Anshan Shan
- The Laboratory of Molecular Nutrition and Immunity, Institute of Animal Nutrition, Northeast Agricultural University, Harbin 150030 P. R. China
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4
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Molecular reprogramming and phenotype switching in Staphylococcus aureus lead to high antibiotic persistence and affect therapy success. Proc Natl Acad Sci U S A 2021; 118:2014920118. [PMID: 33574060 DOI: 10.1073/pnas.2014920118] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Staphylococcus aureus causes invasive infections and easily acquires antibiotic resistance. Even antibiotic-susceptible S. aureus can survive antibiotic therapy and persist, requiring prolonged treatment and surgical interventions. These so-called persisters display an arrested-growth phenotype, tolerate high antibiotic concentrations, and are associated with chronic and recurrent infections. To characterize these persisters, we assessed S. aureus recovered directly from a patient suffering from a persistent infection. We show that host-mediated stress, including acidic pH, abscess environment, and antibiotic exposure promoted persister formation in vitro and in vivo. Multiomics analysis identified molecular changes in S. aureus in response to acid stress leading to an overall virulent population. However, further analysis of a persister-enriched population revealed major molecular reprogramming in persisters, including down-regulation of virulence and cell division and up-regulation of ribosomal proteins, nucleotide-, and amino acid-metabolic pathways, suggesting their requirement to fuel and maintain the persister phenotype and highlighting that persisters are not completely metabolically inactive. Additionally, decreased aconitase activity and ATP levels and accumulation of insoluble proteins involved in transcription, translation, and energy production correlated with persistence in S. aureus, underpinning the molecular mechanisms that drive the persister phenotype. Upon regrowth, these persisters regained their virulence potential and metabolically active phenotype, including reduction of insoluble proteins, exhibiting a reversible state, crucial for recurrent infections. We further show that a targeted antipersister combination therapy using retinoid derivatives and antibiotics significantly reduced lag-phase heterogeneity and persisters in a murine infection model. Our results provide molecular insights into persisters and help explain why persistent S. aureus infections are so difficult to treat.
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5
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Vulin C, Leimer N, Huemer M, Ackermann M, Zinkernagel AS. Prolonged bacterial lag time results in small colony variants that represent a sub-population of persisters. Nat Commun 2018; 9:4074. [PMID: 30287875 PMCID: PMC6172231 DOI: 10.1038/s41467-018-06527-0] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 09/04/2018] [Indexed: 12/21/2022] Open
Abstract
Persisters are a subpopulation of bacteria that are not killed by antibiotics even though they lack genetic resistance. Here we provide evidence that persisters can manifest as small colony variants (SCVs) in clinical infections. We analyze growth kinetics of Staphylococcus aureus sampled from in vivo conditions and in vitro stress conditions that mimic growth in host compartments. We report that SCVs arise as a result of a long lag time, and that this phenotype emerges de novo during the growth phase in various stress conditions including abscesses and acidic media. We further observe that long lag time correlates with antibiotic usage. These observations suggest that treatment strategies should be carefully tailored to address bacterial persisters in clinics. Persisters are bacterial subpopulations that are not killed by antibiotics even though they lack genetic resistance. Here, the authors show that persisters can manifest as small colony variants in clinical infections, and arise as a result of a long lag time in stress conditions including antibiotic exposure.
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Affiliation(s)
- Clément Vulin
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, 8092, Switzerland.,Department of Environmental Microbiology, Eawag, Dubendorf, 8600, Switzerland
| | - Nadja Leimer
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, 8091, Switzerland.,Antimicrobial Discovery Center, Department of Biology, Northeastern University, Boston, MA, 02115, USA
| | - Markus Huemer
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, 8091, Switzerland
| | - Martin Ackermann
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, 8092, Switzerland. .,Department of Environmental Microbiology, Eawag, Dubendorf, 8600, Switzerland.
| | - Annelies S Zinkernagel
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, 8091, Switzerland.
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In Vitro Activity of Delafloxacin and Microbiological Response against Fluoroquinolone-Susceptible and Nonsusceptible Staphylococcus aureus Isolates from Two Phase 3 Studies of Acute Bacterial Skin and Skin Structure Infections. Antimicrob Agents Chemother 2017. [PMID: 28630189 PMCID: PMC5571289 DOI: 10.1128/aac.00772-17] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Delafloxacin is an investigational anionic fluoroquinolone antibiotic with broad-spectrum in vitro activity, including activity against Gram-positive organisms, Gram-negative organisms, atypical organisms, and anaerobes. The in vitro activity of delafloxacin and the percent microbiological response in subjects infected with fluoroquinolone-susceptible and nonsusceptible Staphylococcus aureus isolates were determined from two global phase 3 studies of delafloxacin versus vancomycin plus aztreonam in patients with acute bacterial skin and skin structure infections (ABSSSI). Patients from 23 countries, predominately the United States but also Europe, South America, and Asia, were enrolled. The microbiological intent-to-treat (MITT) population included 1,042 patients from which 685 S. aureus isolates were submitted for identification and susceptibility testing per CLSI guidelines at the central laboratory (JMI Laboratories, North Liberty, IA). The comparator fluoroquinolone antibiotics included levofloxacin and ciprofloxacin. Nonsusceptibility to these antibiotics was determined using CLSI breakpoints. S. aureus isolates were 33.7% levofloxacin nonsusceptible (LVX-NS). The delafloxacin MIC90 values against levofloxacin-nonsusceptible S. aureus, methicillin-resistant S. aureus (MRSA), and methicillin-susceptible S. aureus isolates were all 0.25 μg/ml. Delafloxacin demonstrated high rates of microbiological response against LVX-NS isolates as well as isolates with documented mutations in the quinolone resistance-determining region (QRDR). S. aureus was eradicated or presumed eradicated in 98.4% (245/249) of delafloxacin-treated patients. Similar eradication rates were observed for delafloxacin-treated subjects with levofloxacin-nonsusceptible S. aureus isolates (80/81; 98.8%) and MRSA isolates (70/71; 98.6%). Microbiological response rates of 98.6% were observed with delafloxacin-treated subjects with S. aureus isolates with the S84L mutation in gyrA and the S80Y mutation in parC, the most commonly observed mutations in global phase 3 studies. The data suggest that delafloxacin could be a good option for the treatment of infections caused by S. aureus isolates causing ABSSSI, including MRSA isolates, where high rates of ciprofloxacin and levofloxacin nonsusceptibility are observed. (The phase 3 studies described in this paper have been registered at ClinicalTrials.gov under identifiers NCT01984684 and NCT01811732.)
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7
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Panda S, Ding JL. Natural antibodies bridge innate and adaptive immunity. THE JOURNAL OF IMMUNOLOGY 2016; 194:13-20. [PMID: 25527792 DOI: 10.4049/jimmunol.1400844] [Citation(s) in RCA: 202] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Natural Abs, belonging to isotypes IgM, IgG3, and IgA, were discovered nearly half a century ago. Despite knowledge about the role of the polyreactive natural IgM in pathogen elimination, B cell survival and homeostasis, inflammatory diseases, and autoimmunity, there is a lack of clarity about the physiological role of natural IgG and natural IgA because they appear incapable of recognizing Ags on their own and are perceived as nonreactive. However, recent research revealed exciting functions of natural IgG in innate immunity. Natural IgG:lectin collaboration swiftly and effectively kills invading pathogens. These advances prompt further examination of natural Abs in immune defense and homeostasis, with the potential for developing novel therapeutics. This review provides new insights into the interaction between natural Abs and lectins, with implications on how interactions between molecules of the innate and adaptive immune systems bridge these two arms of immunity.
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Affiliation(s)
- Saswati Panda
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Jeak L Ding
- Department of Biological Sciences, National University of Singapore, Singapore 117543
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8
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Kang S, Park E, Kim Y, Lee S, Kwon J, Cho H, Lee Y. A medusa-like β-cyclodextrin with 1-methyl-2-(2′-carboxyethyl) maleic anhydrides, a potential carrier for pH-sensitive drug delivery. J Drug Target 2014; 22:658-68. [DOI: 10.3109/1061186x.2014.928718] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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9
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Arginine deiminase in Staphylococcus epidermidis functions to augment biofilm maturation through pH homeostasis. J Bacteriol 2014; 196:2277-89. [PMID: 24727224 DOI: 10.1128/jb.00051-14] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Allelic replacement mutants were constructed within arginine deiminase (arcA1 and arcA2) to assess the function of the arginine deiminase (ADI) pathway in organic acid resistance and biofilm formation of Staphylococcus epidermidis 1457. A growth-dependent acidification assay (pH ∼5.0 to ∼5.2) determined that strain 1457 devoid of arginine deiminase activity (1457 ΔADI) was significantly less viable than the wild type following depletion of glucose and in the presence of arginine. However, no difference in viability was noted for individual 1457 ΔarcA1 (native) or ΔarcA2 (arginine catabolic mobile element [ACME]-derived) mutants, suggesting that the native and ACME-derived ADIs are compensatory in S. epidermidis. Furthermore, flow cytometry and electron paramagnetic resonance spectroscopy results suggested that organic acid stress resulted in oxidative stress that could be partially rescued by the iron chelator dipyridyl. Collectively, these results suggest that formation of hydroxyl radicals is partially responsible for cell death via organic acid stress and that ADI-derived ammonia functions to counteract this acid stress. Finally, static biofilm assays determined that viability, ammonia synthesis, and pH were reduced in strain 1457 ΔADI following 120 h of growth in comparison to strain 1457 and the arcA1 and arcA2 single mutants. It is hypothesized that ammonia synthesis via the ADI pathway is important to reduce pH stress in specific microniches that contain high concentrations of organic acids.
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10
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Panda S, Zhang J, Yang L, Anand GS, Ding JL. Molecular interaction between natural IgG and ficolin--mechanistic insights on adaptive-innate immune crosstalk. Sci Rep 2014; 4:3675. [PMID: 24419227 PMCID: PMC3891018 DOI: 10.1038/srep03675] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 12/13/2013] [Indexed: 11/09/2022] Open
Abstract
Recently, we found that natural IgG (nIgG; a non-specific immunoglobulin of adaptive immunity) is not quiescent, but plays a crucial role in immediate immune defense by collaborating with ficolin (an innate immune protein). However, how the nIgG and ficolin interplay and what factors control the complex formation during infection is unknown. Here, we found that mild acidosis and hypocalcaemia induced by infection- inflammation condition increased the nIgG:ficolin complex formation. Hydrogen-deuterium exchange mass spectrometry delineated the binding interfaces to the CH2-CH3 region of nIgG Fc and P-subdomain of ficolin FBG domain. Infection condition exposes novel binding sites. Site-directed mutagenesis and surface plasmon resonance analyses of peptides, derived from nIgG and ficolin, defined the interacting residues between the proteins. These results provide mechanistic insights on the interaction between two molecules representing the adaptive and innate immune pathways, prompting potential development of immunomodulatory/prophylactic peptides tunable to prevailing infection conditions.
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Affiliation(s)
- Saswati Panda
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543
| | - Jing Zhang
- NUS graduate School for Integrative Science and Engineering, National University of Singapore, Singapore, 117543
- Current address: FIMS & BJRC, The 1 Affiliated Hospital and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China, 710061
| | - Lifeng Yang
- Computational and Systems Biology, Singapore-MIT Alliance, 4 Engineering Drive 3, Singapore, 117576
- Current address: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637511
| | - Ganesh S. Anand
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543
| | - Jeak L. Ding
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543
- Computational and Systems Biology, Singapore-MIT Alliance, 4 Engineering Drive 3, Singapore, 117576
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11
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Tseng LL, Ho CM, Liang WZ, Hsieh YD, Jan CR. Comparison of efficacies of different bone substitutes adhered to osteoblasts with and without extracellular matrix proteins. J Dent Sci 2013. [DOI: 10.1016/j.jds.2012.03.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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12
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Panda S, Zhang J, Tan NS, Ho B, Ding JL. Natural IgG antibodies provide innate protection against ficolin-opsonized bacteria. EMBO J 2013; 32:2905-19. [PMID: 24002211 PMCID: PMC3831310 DOI: 10.1038/emboj.2013.199] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 08/08/2013] [Indexed: 11/09/2022] Open
Abstract
For nearly five decades since its discovery, the role of natural IgG, which pre-exists in neonates and uninfected individuals, has remained unclear due to the general perception that natural antibodies lack affinity for pathogens. Here, we show for the first time that natural IgG recognizes a spectrum of bacteria through lectins like ficolin and mannose binding lectin (MBL). Infection-inflammation condition markedly increased the affinity of natural IgG for bacteria associated with ficolins. After opsonization with IgG:ficolin complex, the bacteria were phagocytosed by monocytes via FcγRI. Infection of C3(-/-) mice indicated that the natural IgG-mediated immune complex was formed independently of C3. AID(-/-) mice lacking IgG were susceptible to infection, unless reconstituted with natural IgG. Thus, we have proven that natural IgG is not quiescent; rather, it plays a vital and immediate role in immune defense. Our findings provide a fresh perspective on natural antibodies, opening new avenues to explore host-microbe interaction.
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Affiliation(s)
- Saswati Panda
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Jing Zhang
- NUS Graduate School for Integrative Science and Engineering, National University of Singapore, Singapore, Singapore
| | - Nguan Soon Tan
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- Institute of Molecular and Cell Biology, Proteos, Singapore
| | - Bow Ho
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jeak Ling Ding
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Singapore
- Singapore MIT Alliance, National University of Singapore, Singapore, Singapore
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13
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Driscoll CL, Green JD, Beatty CW, McCaffrey TV, Marrs CD. In vitro Characteristics of a Glass Ionomer Cement. Skull Base Surg 2011; 8:175-80. [PMID: 17171062 PMCID: PMC1656712 DOI: 10.1055/s-2008-1058179] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Glass ionomer cements were first described by Wilson and Kent and have been used in dentistry since 1969. It has been recommended for bridging ossicular chain defects, fixation of ossicular chain prosthesis, anchoring of cochlear implants, mastoid obliteration, and repair of tegmen and posterior canal wall defects. The biocompatability and stability of this material over time is vital to its usefulness in neurotologic surgery. The purpose of this study was to assess the stability of a glass ionomer cement in the presence of bacteria and in different pH environments. We demonstrated that bacteria readily adhere to the surface and their presence is associated with accelerated loss of matrix. We found the cement to be susceptible to low pH and to release a visible cloud of debris upon contact with fluid. Calcium concentration in the solution was elevated at all pH levels. Although we are able to demonstrate these findings in vitro the clinical relevance is unclear. There have been several cases of aseptic meningitis possibly due to intracranial release of components of the cement. Until further studies are done use of the cement in contact with cerebral spinal fluid should be avoided. This cement, or a similar material, would be useful in neurotologic surgery but prior to widespread use further testing should be done to assess safety.
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14
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Kinnari TJ, Esteban J, Martin-de-Hijas NZ, Sánchez-Muñoz O, Sánchez-Salcedo S, Colilla M, Vallet-Regí M, Gomez-Barrena E. Influence of surface porosity and pH on bacterial adherence to hydroxyapatite and biphasic calcium phosphate bioceramics. J Med Microbiol 2009; 58:132-137. [PMID: 19074665 DOI: 10.1099/jmm.0.002758-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hydroxyapatite (HA) and biphasic calcium phosphate (BCP) ceramic materials are widely employed as bone substitutes due to their porous and osteoconductive structure. Their porosity and the lowering of surrounding pH as a result of surgical trauma may, however, predispose these materials to bacterial infections. For this reason, the influence of porosity and pH on the adherence of common Gram-positive bacteria to the surfaces of these materials requires investigation. Mercury intrusion porosimetry measurements revealed that the pore size distribution of both bioceramics had, on a logarithmic scale, a sinusoidal frequency distribution ranging from 50 to 300 nm, with a mean pore diameter of 200 nm. Moreover, total porosity was 20 % for HA and 50 % for BCP. Adherence of Staphylococcus aureus and Staphylococcus epidermidis was studied at a physiological pH of 7.4 and at a pH simulating bone infection of 6.8. Moreover, the effect of pH on the zeta potential of HA, BCP and of both staphylococci was evaluated. Results showed that when pH decreased from 7.4 to 6.8, the adherence of both staphylococci to HA and BCP surfaces decreased significantly, although at the same time the negative zeta-potential values of the ceramic surfaces and both bacteria diminished. At both pH values, the number of S. aureus adhered to the HA surface appeared to be lower than that for BCP. A decrease in pH to 6.8 reduced the adherence of both bacterial species (mean 57 %). This study provides evidence that HA and BCP ceramics do not have pores sufficiently large to allow the internalization of staphylococci. Their anti-adherent properties seemed to improve when pH value decreased, suggesting that HA and BCP bioceramics are not compromised upon orthopaedic use.
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Affiliation(s)
- Teemu J Kinnari
- Department of Otolaryngology, Helsinki University Central Hospital, PO Box 220, FI-00029 HUS, Finland.,Department of Orthopaedic Surgery and Traumatology, Fundación Jiménez Díaz-UTE, Avda de Reyes Católicos 2, E-28040 Madrid, Spain.,Department of Clinical Microbiology, Fundación Jiménez Díaz-UTE, Avda de Reyes Católicos 2, E-28040 Madrid, Spain
| | - Jaime Esteban
- Department of Clinical Microbiology, Fundación Jiménez Díaz-UTE, Avda de Reyes Católicos 2, E-28040 Madrid, Spain
| | - Nieves Z Martin-de-Hijas
- Department of Clinical Microbiology, Fundación Jiménez Díaz-UTE, Avda de Reyes Católicos 2, E-28040 Madrid, Spain
| | - Orlando Sánchez-Muñoz
- Instituto de Ciencias de los Materiales, Universidad de Valencia, PO Box 22085, E-46071 Valencia, Spain.,Department of Medicine, Helsinki University Central Hospital, PO Box 700, FI-00029 HUS, Finland
| | - Sandra Sánchez-Salcedo
- Department of Inorganic and Bioinorganic Chemistry, Faculty of Pharmacy, Complutense University of Madrid, Plaza Ramón y Cajal s/n, E-28040 Madrid, Spain
| | - Montserrat Colilla
- Department of Inorganic and Bioinorganic Chemistry, Faculty of Pharmacy, Complutense University of Madrid, Plaza Ramón y Cajal s/n, E-28040 Madrid, Spain
| | - María Vallet-Regí
- Department of Inorganic and Bioinorganic Chemistry, Faculty of Pharmacy, Complutense University of Madrid, Plaza Ramón y Cajal s/n, E-28040 Madrid, Spain
| | - Enrique Gomez-Barrena
- Department of Orthopaedic Surgery and Traumatology, Fundación Jiménez Díaz-UTE, Avda de Reyes Católicos 2, E-28040 Madrid, Spain
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15
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Weinrick B, Dunman PM, McAleese F, Murphy E, Projan SJ, Fang Y, Novick RP. Effect of mild acid on gene expression in Staphylococcus aureus. J Bacteriol 2005; 186:8407-23. [PMID: 15576791 PMCID: PMC532443 DOI: 10.1128/jb.186.24.8407-8423.2004] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During staphylococcal growth in glucose-supplemented medium, the pH of a culture starting near neutrality typically decreases by about 2 units due to the fermentation of glucose. Many species can comfortably tolerate the resulting mildly acidic conditions (pH, approximately 5.5) by mounting a cellular response, which serves to defend the intracellular pH and, in principle, to modify gene expression for optimal performance in a mildly acidic infection site. In this report, we show that changes in staphylococcal gene expression formerly thought to represent a glucose effect are largely the result of declining pH. We examine the cellular response to mild acid by microarray analysis and define the affected gene set as the mild acid stimulon. Many of the genes encoding extracellular virulence factors are affected, as are genes involved in regulation of virulence factor gene expression, transport of sugars and peptides, intermediary metabolism, and pH homeostasis. Key results are verified by gene fusion and Northern blot hybridization analyses. The results point to, but do not define, possible regulatory pathways by which the organism senses and responds to a pH stimulus.
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Affiliation(s)
- Brian Weinrick
- Program in Molecular Pathogenesis, Skirball Institute, and Department of Microbiology, New York University School of Medicine, 540 First Ave., New York, NY 10016, USA
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Claessens RA, Koenders EB, Boerman OC, Oyen WJ, Borm GF, van der Meer JW, Corstens FH. Dissociation of indium from indium-111-labelled diethylene triamine penta-acetic acid conjugated non-specific polyclonal human immunoglobulin G in inflammatory foci. EUROPEAN JOURNAL OF NUCLEAR MEDICINE 1995; 22:212-9. [PMID: 7789393 DOI: 10.1007/bf01081515] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Several investigators have reported retention of indium-111 in infectious foci after intravenous injection of 111In-labelled immunoglobulin G (IgG). With this study we intended to test the hypothesis that, upon administration of 111In-diethylene triamine penta-acetic acid (DTPA-IgG), 111In is retained in the infectious foci after dissociation from IgG. Therefore we measured the tissue distribution of double-labelled 111In-DTPA-IgG-(carbon-14) in rats with a focal infection and compared the results with corresponding data for DTPA-IgG-(14C). DTPA-conjugated IgG was labelled with 111In via citrate transchelation. 111In-DTPA-IgG and DTPA-IgG were labelled with 14C through methylation. High-performance liquid chromatography (HPLC) and instant thin-layer chromatography analysis were performed to test the in vitro stability of the labelled proteins. Young Wistar rats with a Staphylococcus aureus infection of the left calf muscle were injected intravenously with 0.2 ml of a solution containing either 0.4 MBq 111In and 30 kBq 14C or 30 kBq 14C labelled to 80 micrograms IgG. Groups of five rats were sacrificed at 2, 6, 24, and 48 h. p.i. Activity uptake was determined for plasma, urine, abscess, muscle and various other tissues. Averages and standard deviations were calculated for groups of five rats. HPLC analysis was performed on plasma and urine samples taken up to 48 h p.i. The radiochemical purity of the IgG preparations was > 95%. The labelled preparations appeared stable in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R A Claessens
- Department of Nuclear Medicine, University Hospital Nijmegen, The Netherlands
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