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Kaplan JB, Horswill AR. Micrococcal nuclease regulates biofilm formation and dispersal in methicillin-resistant Staphylococcus aureus USA300. mSphere 2024; 9:e0012624. [PMID: 38695568 PMCID: PMC11237449 DOI: 10.1128/msphere.00126-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 03/21/2024] [Indexed: 05/14/2024] Open
Abstract
Biofilm formation is an important virulence factor for methicillin-resistant Staphylococcus aureus (MRSA). The extracellular matrix of MRSA biofilms contains significant amounts of double-stranded DNA that hold the biofilm together. MRSA cells secrete micrococcal nuclease (Nuc1), which degrades double-stranded DNA. In this study, we used standard methodologies to investigate the role of Nuc1 in MRSA biofilm formation and dispersal. We quantified biofilm formation and extracellular DNA (eDNA) levels in broth and agar cultures. In some experiments, cultures were supplemented with sub-MIC amoxicillin to induce biofilm formation. Biofilm erosion was quantitated by culturing biofilms on rods and enumerating detached colony-forming units (CFUs), and biofilm sloughing was investigated by perfusing biofilms cultured in glass tubes with fresh broth and measuring the sizes of the detached cell aggregates. We found that an MRSA nuc1- mutant strain produced significantly more biofilm and more eDNA than a wild-type strain, both in the absence and presence of sub-MIC amoxicillin. nuc1- mutant biofilms grown on rods detached significantly less than wild-type biofilms. Detachment was restored by exogenous DNase or complementing the nuc1- mutant. In the sloughing assay, nuc1- mutant biofilms released cell aggregates that were significantly larger than those released by wild-type biofilms. Our results suggest that Nuc1 modulates biofilm formation, biofilm detachment, and the sizes of detached cell aggregates. These processes may play a role in the spread and subsequent survival of MRSA biofilms during biofilm-related infections.IMPORTANCEInfections caused by antibiotic-resistant bacteria known as methicillin-resistant Staphylococcus aureus (MRSA) are a significant problem in hospitals. MRSA forms adherent biofilms on implanted medical devices such as catheters and breathing tubes. Bacteria can detach from biofilms on these devices and spread to other parts of the body such as the blood or lungs, where they can cause life-threatening infections. In this article, researchers show that MRSA secretes an enzyme known as thermonuclease that causes bacteria to detach from the biofilm. This is important because understanding the mechanism by which MRSA detaches from biofilms could lead to the development of procedures to mitigate the problem.
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Kaplan JB, Cywes-Bentley C, Pier GB, Yakandawala N, Sailer M, Edwards MS, Kridin K. Poly- β-(1→6)- N-acetyl-D-glucosamine mediates surface attachment, biofilm formation, and biocide resistance in Cutibacterium acnes. Front Microbiol 2024; 15:1386017. [PMID: 38751716 PMCID: PMC11094747 DOI: 10.3389/fmicb.2024.1386017] [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: 02/14/2024] [Accepted: 04/17/2024] [Indexed: 05/18/2024] Open
Abstract
Background The commensal skin bacterium Cutibacterium acnes plays a role in the pathogenesis of acne vulgaris and also causes opportunistic infections of implanted medical devices due to its ability to form biofilms on biomaterial surfaces. Poly-β-(1→6)-N-acetyl-D-glucosamine (PNAG) is an extracellular polysaccharide that mediates biofilm formation and biocide resistance in a wide range of bacterial pathogens. The objective of this study was to determine whether C. acnes produces PNAG, and whether PNAG contributes to C. acnes biofilm formation and biocide resistance in vitro. Methods PNAG was detected on the surface of C. acnes cells by fluorescence confocal microscopy using the antigen-specific human IgG1 monoclonal antibody F598. PNAG was detected in C. acnes biofilms by measuring the ability of the PNAG-specific glycosidase dispersin B to inhibit biofilm formation and sensitize biofilms to biocide killing. Results Monoclonal antibody F598 bound to the surface of C. acnes cells. Dispersin B inhibited attachment of C. acnes cells to polystyrene rods, inhibited biofilm formation by C. acnes in glass and polypropylene tubes, and sensitized C. acnes biofilms to killing by benzoyl peroxide and tetracycline. Conclusion C. acnes produces PNAG, and PNAG contributes to C. acnes biofilm formation and biocide resistance in vitro. PNAG may play a role in C. acnes skin colonization, biocide resistance, and virulence in vivo.
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Kaplan JB, Florjanczyk AP, Ochiai M, Jones CD, Horswill AR. Micrococcal nuclease regulates biofilm formation and dispersal in methicillin-resistant Staphylococcus aureus USA300. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.05.565664. [PMID: 37961602 PMCID: PMC10635163 DOI: 10.1101/2023.11.05.565664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Biofilm formation is an important virulence factor for methicillin-resistant Staphylococcus aureus (MRSA). The extracellular matrix of MRSA biofilms contains significant amounts of double-stranded DNA. MRSA cells also secrete micrococcal nuclease (Nuc1) which degrades double-stranded DNA. In this study we used a nuc1 mutant strain to investigate the role of Nuc1 in MRSA biofilm formation and dispersal. Biofilm was quantitated in microplates using a crystal violet binding assay. Extracellular DNA (eDNA) was isolated from colony biofilms and analyzed by agarose gel electrophoresis. In some experiments, broth or agar was supplemented with sub-MIC amoxicillin to induce biofilm formation. Biofilm erosion was quantitated by culturing biofilms on rods, transferring the rods to fresh broth, and enumerating CFUs that detached from the rods. Biofilm sloughing was investigated by culturing biofilms in glass tubes perfused with broth and measuring the sizes of the detached cell aggregates. We found that a nuc1 mutant strain produced significantly more biofilm and more eDNA than a wild-type strain in both the absence and presence of sub-MIC amoxicillin, nuc1 mutant biofilms grown on rods detached significantly less than wild-type biofilms. Detachment was restored by exogenous DNase or a wild-type nuc1 gene on a plasmid. In the sloughing assay, nuc1 mutant biofilms released cell aggregates that were significantly larger than those released by wild-type biofilms. Our results suggest that Nuc1 modulates biofilm formation, biofilm detachment, and the sizes of detached cell aggregates. These processes may play a role in the spread and subsequent survival of MRSA biofilms during biofilm-related infections.
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Triggs JR, Krogh K, Simon V, Krause A, Kaplan JB, Yang GY, Wani S, Kahrilas PJ, Pandolfino J, Komanduri S. Novel histologic score predicts recurrent intestinal metaplasia after successful endoscopic eradication therapy. Dis Esophagus 2023; 36:doac078. [PMID: 36446594 PMCID: PMC10150172 DOI: 10.1093/dote/doac078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 09/17/2022] [Accepted: 10/08/2022] [Indexed: 12/02/2022]
Abstract
Endoscopic eradication therapy (EET) is an effective treatment for Barrett's esophagus (BE); however, disease recurrence remains problematic requiring surveillance post-treatment. While data regarding predictors of recurrence are limited, uncontrolled reflux may play a significant role. Our aim was to develop a scoring system based on histopathologic reflux in surveillance biopsies following EET to identify patients at high risk for recurrence of BE. Patients were identified from two centers in the treatment with resection and endoscopic ablation techniques for BE consortium. Hematoxylin and eosin-stained slides of surveillance biopsies post-EET were assessed for histologic changes associated with reflux from a cohort of patients who also underwent pH-metry (derivation cohort). We developed a novel scoring system (Recurrent Epithelial Changes from Uncontrolled Reflux [RECUR]) composed of dilated intercellular spaces, epithelial ballooning, basal cell hyperplasia, and parakeratosis, to identify patients with abnormal esophageal acid exposure. This scoring system was then used to grade surveillance biopsies from patients with or without recurrence of BE following EET (validation cohort). Of 41 patients in the derivation cohort, 19.5% had abnormal acid exposure times (AET) while on proton pump inhibitor therapy. The mean (SD) RECUR score for patients with AET <4% was 4.0 (1.6), compared with 5.5 (0.9) for AET ≥4% (P = 0.015). In the validation cohort consisting of 72 patients without recurrence and 64 patients with recurrence following EET, the RECUR score was the only significant predictor of recurrence (odds ratio: 1.36, 95% confidence interval: 1.10-1.69, P = 0.005). Histologic grading of surveillance biopsies using the RECUR scoring system correlates with BE recurrence following EET.
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Kaplan JB, Mlynek KD, Hettiarachchi H, Alamneh YA, Biggemann L, Zurawski DV, Black CC, Bane CE, Kim RK, Granick MS. Extracellular polymeric substance (EPS)-degrading enzymes reduce staphylococcal surface attachment and biocide resistance on pig skin in vivo. PLoS One 2018; 13:e0205526. [PMID: 30304066 PMCID: PMC6179274 DOI: 10.1371/journal.pone.0205526] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 09/26/2018] [Indexed: 02/04/2023] Open
Abstract
Staphylococcal extracellular polymeric substances (EPS) such as extracellular DNA (eDNA) and poly-N-acetylglucosamine surface polysaccharide (PNAG) mediate numerous virulence traits including host colonization and antimicrobial resistance. Previous studies showed that EPS-degrading enzymes increase staphylococcal biocide susceptibility in vitro and in vivo, and decrease virulence in animal models. In the present study we tested the effect of EPS-degrading enzymes on staphylococcal skin colonization and povidone iodine susceptibility using a novel in vivo pig model that enabled us to colonize and treat 96 isolated areas of skin on a single animal in vivo. To quantitate skin colonization, punch biopsies of colonized areas were homogenized, diluted, and plated on agar for colony forming unit enumeration. Skin was colonized with either Staphylococcus epidermidis or Staphylococcus aureus. Two EPS-degrading enzymes, DNase I and the PNAG-degrading enzyme dispersin B, were employed. Enzymes were tested for their ability to inhibit skin colonization and detach preattached bacteria. The effect of enzymes on the susceptibility of preattached S. aureus to killing by povidone iodine was also measured. We found that dispersin B significantly inhibited skin colonization by S. epidermidis and detached preattached S. epidermidis cells from skin. A cocktail of dispersin B and DNase I detached preattached S. aureus cells from skin and increased their susceptibility to killing by povidone iodine. These findings suggest that staphylococcal EPS components such as eDNA and PNAG contribute to skin colonization and biocide resistance in vivo. EPS-degrading enzymes may be a useful adjunct to conventional skin antisepsis procedures in order to further reduce skin bioburden.
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Mittal C, Obuch JC, Hammad H, Edmundowicz SA, Wani S, Shah RJ, Brauer BC, Attwell AR, Kaplan JB, Wagh MS. Technical feasibility, diagnostic yield, and safety of microforceps biopsies during EUS evaluation of pancreatic cystic lesions (with video). Gastrointest Endosc 2018; 87:1263-1269. [PMID: 29309781 DOI: 10.1016/j.gie.2017.12.025] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 12/03/2017] [Indexed: 02/08/2023]
Abstract
BACKGROUND AND AIMS Through-the-needle microforceps are a recent addition to the EUS armamentarium for evaluation of pancreatic cystic lesions (PCLs). The main aim of this study was to assess the technical feasibility, diagnostic yield, and safety of EUS-guided microforceps biopsy for PCLs. METHODS Our electronic endoscopy database was queried to identify patients who underwent EUS-guided FNA (EUS-FNA) of PCLs and microforceps biopsies during the same procedure. A biopsy was done on the wall of the cyst with the microforceps through the 19-gauge needle, and cyst fluid was collected for cytology and carcinoembryonic antigen (CEA) levels. Adverse events were recorded per published American Society for Gastrointestinal Endoscopy criteria. RESULTS Twenty-seven patients underwent EUS-FNA and microforceps biopsy of PCLs from February 2016 to July 2017. Fourteen cysts were located in the pancreatic head and/or uncinate, and 13 were located in the body and/or tail region. Microforceps biopsies were technically successful in all cases and provided a pathology diagnosis in 24 of 27 cases (yield 88.9%). Microforceps biopsies diagnosed mucinous cyst in 9 patients (33.3%), serous cystadenoma in 4 (14.8%), neuroendocrine tumor in 1 (3.7%), and benign and/or inflammatory cyst in 10 (37.1%). In 7 patients (26%), microforceps biopsy results drastically changed the diagnosis, providing diagnoses otherwise not suggested by cytology or cyst fluid CEA levels. However, cytology provided a diagnosis of mucinous cyst in 4 cases (14.8%) not detected by microforceps biopsies. No adverse events were noted. CONCLUSION Microforceps biopsies were associated with high technical success, and an excellent safety profile and may be a useful adjunctive tool, complementing existing EUS-FNA sampling protocols for PCLs.
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Abstract
Surface-attached colonies of bacteria known as biofilms play a major role in the pathogenesis of medical device infections. Biofilm colonies are notorious for their resistance to antibiotics and host defenses, which makes most device infections difficult or impossible to eradicate. Bacterial cells in a biofilm are held together by an extracellular polymeric matrix that is synthesized by the bacteria themselves. Enzymes that degrade biofilm matrix polymers have been shown to inhibit bio film formation, detach established bio film colonies, and render biofilm cells sensitive to killing by antimicrobial agents. This review discusses the potential use of biofilm matrix-degrading enzymes as anti-biofilm agents for the treatment and prevention of device infections. Two enzymes, deoxyribonuclease I and the glycoside hydrolase dispersin B, will be reviewed in detail. In vitro and in vivo studies demonstrating the anti-biofilm activities of these two enzymes will be summarized, and the therapeutic potential and possible drawbacks of using these enzymes as clinical agents will be discussed.
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Kaplan JB, Sampathkumar V, Bendaoud M, Giannakakis AK, Lally ET, Balashova NV. In vitro characterization of biofilms formed by Kingella kingae. Mol Oral Microbiol 2016; 32:341-353. [PMID: 27714987 DOI: 10.1111/omi.12176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2016] [Indexed: 01/29/2023]
Abstract
The Gram-negative bacterium Kingella kingae is part of the normal oropharyngeal mucosal flora of children <4 years old. K. kingae can enter the submucosa and cause infections of the skeletal system in children, including septic arthritis and osteomyelitis. The organism is also associated with infective endocarditis in children and adults. Although biofilm formation has been coupled with pharyngeal colonization, osteoarticular infections, and infective endocarditis, no studies have investigated biofilm formation in K. kingae. In this study we measured biofilm formation by 79 K. kingae clinical isolates using a 96-well microtiter plate crystal violet binding assay. We found that 37 of 79 strains (47%) formed biofilms. All strains that formed biofilms produced corroding colonies on agar. Biofilm formation was inhibited by proteinase K and DNase I. DNase I also caused the detachment of pre-formed K. kingae biofilm colonies. A mutant strain carrying a deletion of the pilus gene cluster pilA1pilA2fimB did not produce corroding colonies on agar, autoaggregate in broth, or form biofilms. Biofilm forming strains have higher levels of pilA1 expression. The extracellular components of biofilms contained 490 μg cm-2 of protein, 0.68 μg cm-2 of DNA, and 0.4 μg cm-2 of total carbohydrates. We concluded that biofilm formation is common among K. kingae clinical isolates, and that biofilm formation is dependent on the production of proteinaceous pili and extracellular DNA. Biofilm development may have relevance to the colonization, transmission, and pathogenesis of this bacterium. Extracellular DNA production by K. kingae may facilitate horizontal gene transfer within the oral microbial community.
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Boniface MM, Wani SB, Schefter TE, Koo PJ, Meguid C, Leong S, Kaplan JB, Wingrove LJ, McCarter MD. Multidisciplinary management for esophageal and gastric cancer. Cancer Manag Res 2016; 8:39-44. [PMID: 27217796 PMCID: PMC4853141 DOI: 10.2147/cmar.s101169] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The management of esophageal and gastric cancer is complex and involves multiple specialists in an effort to optimize patient outcomes. Utilizing a multidisciplinary team approach starting from the initial staging evaluation ensures that all members are in agreement with the plan of care. Treatment selection for esophageal and gastric cancer often involves a combination of chemotherapy, radiation, surgery, and palliative interventions (endoscopic and surgical), and direct communication between specialists in these fields is needed to ensure appropriate clinical decision making. At the University of Colorado, the Esophageal and Gastric Multidisciplinary Clinic was created to bring together all experts involved in treating these diseases at a weekly conference in order to provide patients with coordinated, individualized, and patient-centered care. This review details the essential elements and benefits of building a multidisciplinary program focused on treating esophageal and gastric cancer patients.
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Shanmugam M, Gopal P, El Abbar F, Schreiner HC, Kaplan JB, Fine DH, Ramasubbu N. Role of exopolysaccharide in Aggregatibacter actinomycetemcomitans-induced bone resorption in a rat model for periodontal disease. PLoS One 2015; 10:e0117487. [PMID: 25706999 PMCID: PMC4338281 DOI: 10.1371/journal.pone.0117487] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 12/24/2014] [Indexed: 11/19/2022] Open
Abstract
Aggregatibacter actinomycetemcomitans a causative agent of periodontal disease in humans, forms biofilm on biotic and abiotic surfaces. A. actinomycetemcomitans biofilm is heterogeneous in nature and is composed of proteins, extracellular DNA and exopolysaccharide. To explore the role played by the exopolysaccharide in the colonization and disease progression, we employed genetic reduction approach using our rat model of A. actinomycetemcomitans-induced periodontitis. To this end, a genetically modified strain of A. actinomycetemcomitans lacking the pga operon was compared with the wild-type strain in the rat infection model. The parent and mutant strains were primarily evaluated for bone resorption and disease. Our study showed that colonization, bone resorption/disease and antibody response were all elevated in the wild-type fed rats. The bone resorption/disease caused by the pga mutant strain, lacking the exopolysaccharide, was significantly less (P < 0.05) than the bone resorption/disease caused by the wild-type strain. Further analysis of the expression levels of selected virulence genes through RT-PCR showed that the decrease in colonization, bone resorption and antibody titer in the absence of the exopolysaccharide might be due to attenuated levels of colonization genes, flp-1, apiA and aae in the mutant strain. This study demonstrates that the effect exerted by the exopolysaccharide in A. actinomycetemcomitans-induced bone resorption has hitherto not been recognized and underscores the role played by the exopolysaccharide in A. actinomycetemcomitans-induced disease.
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Nait Chabane Y, Marti S, Rihouey C, Alexandre S, Hardouin J, Lesouhaitier O, Vila J, Kaplan JB, Jouenne T, Dé E. Characterisation of pellicles formed by Acinetobacter baumannii at the air-liquid interface. PLoS One 2014; 9:e111660. [PMID: 25360550 PMCID: PMC4216135 DOI: 10.1371/journal.pone.0111660] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 09/25/2014] [Indexed: 11/18/2022] Open
Abstract
The clinical importance of Acinetobacter baumannii is partly due to its natural ability to survive in the hospital environment. This persistence may be explained by its capacity to form biofilms and, interestingly, A. baumannii can form pellicles at the air-liquid interface more readily than other less pathogenic Acinetobacter species. Pellicles from twenty-six strains were morphologically classified into three groups: I) egg-shaped (27%); II) ball-shaped (50%); and III) irregular pellicles (23%). One strain representative of each group was further analysed by Brewster’s Angle Microscopy to follow pellicle development, demonstrating that their formation did not require anchoring to a solid surface. Total carbohydrate analysis of the matrix showed three main components: Glucose, GlcNAc and Kdo. Dispersin B, an enzyme that hydrolyzes poly-N-acetylglucosamine (PNAG) polysaccharide, inhibited A. baumannii pellicle formation, suggesting that this exopolysaccharide contributes to pellicle formation. Also associated with the pellicle matrix were three subunits of pili assembled by chaperon-usher systems: the major CsuA/B, A1S_1510 (presented 45% of identity with the main pilin F17-A from enterotoxigenic Escherichia coli pili) and A1S_2091. The presence of both PNAG polysaccharide and pili systems in matrix of pellicles might contribute to the virulence of this emerging pathogen.
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Farmer JT, Shimkevitch AV, Reilly PS, Mlynek KD, Jensen KS, Callahan MT, Bushaw-Newton KL, Kaplan JB. Environmental bacteria produce abundant and diverse antibiofilm compounds. J Appl Microbiol 2014; 117:1663-73. [PMID: 25179003 DOI: 10.1111/jam.12639] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 07/23/2014] [Accepted: 08/22/2014] [Indexed: 11/26/2022]
Abstract
AIMS The aim of this study was to isolate novel antibiofilm compounds produced by environmental bacteria. METHODS AND RESULTS Cell-free extracts were prepared from lawns of bacteria cultured on agar. A total of 126 bacteria isolated from soil, cave and river habitats were employed. Extracts were tested for their ability to inhibit Staphylococcus aureus biofilm in a 96-well microtitre plate assay. A total of 55/126 extracts (44%) significantly inhibited Staph. aureus biofilm. Seven extracts were selected for further analysis. The antibiofilm activities in all seven extracts exhibited unique patterns of molecular mass, chemical polarity, heat stability and spectrum of activity against Staph. aureus, Staphylococcus epidermidis and Pseudomonas fluorescens, suggesting that these seven antibiofilm activities were mediated by unique chemical compounds with different mechanisms of action. CONCLUSIONS Environmental bacteria produce abundant and diverse antibiofilm compounds. SIGNIFICANCE AND IMPACT OF THE STUDY Screening cell-free extracts is a useful method for identifying secreted compounds that regulate biofilm formation. Such compounds may represent a novel source of antibiofilm agents for technological development.
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Abstract
Polymeric substances such as proteins, polysaccharides, and DNA constitute a major component of the biofilm matrix. Enzymes that depolymerize and degrade these components are useful tools for investigating the composition and function of the biofilm matrix. This chapter provides a brief overview of the most commonly used biofilm matrix-degrading enzymes and presents examples of their applications in biofilm research.
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Ng M, Epstein SB, Callahan MT, Piotrowski BO, Simon GL, Roberts AD, Keiser JF, Kaplan JB. Induction of MRSA Biofilm by Low-Dose β-Lactam Antibiotics: Specificity, Prevalence and Dose-Response Effects. Dose Response 2013; 12:152-61. [PMID: 24659939 DOI: 10.2203/dose-response.13-021.kaplan] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of hospital- and community-associated infections. The formation of adherent clusters of cells known as biofilms is an important virulence factor in MRSA pathogenesis. Previous studies showed that subminimal inhibitory (sub-MIC) concentrations of methicillin induce biofilm formation in the community-associated MRSA strain LAC. In this study we measured the ability sub-MIC concentrations of eight other β-lactam antibiotics and six non-β-lactam antibiotics to induce LAC biofilm. All eight β-lactam antibiotics, but none of the non-β-lactam antibiotics, induced LAC biofilm. The dose-response effects of the eight β-lactam antibiotics on LAC biofilm varied from biphasic and bimodal to near-linear. We also found that sub-MIC methicillin induced biofilm in 33 out of 39 additional MRSA clinical isolates, which also exhibited biphasic, bimodal and linear dose-response curves. The amount of biofilm formation induced by sub-MIC methicillin was inversely proportional to the susceptibility of each strain to methicillin. Our results demonstrate that induction of biofilm by sub-MIC antibiotics is a common phenotype among MRSA clinical strains and is specific for β-lactam antibiotics. These findings may have relevance to the use of β-lactam antibiotics in clinical and agricultural settings.
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Karwacki MT, Kadouri DE, Bendaoud M, Izano EA, Sampathkumar V, Inzana TJ, Kaplan JB. Antibiofilm activity of Actinobacillus pleuropneumoniae serotype 5 capsular polysaccharide. PLoS One 2013; 8:e63844. [PMID: 23691104 PMCID: PMC3653790 DOI: 10.1371/journal.pone.0063844] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 04/09/2013] [Indexed: 12/14/2022] Open
Abstract
Cell-free extracts isolated from colony biofilms of Actinobacillus pleuropneumoniae serotype 5 were found to inhibit biofilm formation by Staphylococcus aureus, S. epidermidis and Aggregatibacter actinomycetemcomitans, but not by A. pleuropneumoniae serotype 5 itself, in a 96-well microtiter plate assay. Physical and chemical analyses indicated that the antibiofilm activity in the extract was due to high-molecular-weight polysaccharide. Extracts isolated from a mutant strain deficient in the production of serotype 5 capsular polysaccharide did not exhibit antibiofilm activity. A plasmid harboring the serotype 5 capsule genes restored the antibiofilm activity in the mutant extract. Purified serotype 5 capsular polysaccharide also exhibited antibiofilm activity against S. aureus. A. pleuropneumoniae wild-type extracts did not inhibit S. aureus growth, but did inhibit S. aureus intercellular adhesion and binding of S. aureus cells to stainless steel surfaces. Furthermore, polystyrene surfaces coated with A. pleuropneumoniae wild-type extracts, but not with capsule-mutant extracts, resisted S. aureus biofilm formation. Our findings suggest that the A. pleuropneumoniae serotype 5 capsule inhibits cell-to-cell and cell-to-surface interactions of other bacteria. A. pleuropneumoniae serotype 5 capsular polysaccharide is one of a growing number of bacterial polysaccharides that exhibit broad-spectrum, nonbiocidal antibiofilm activity. Future studies on these antibiofilm polysaccharides may uncover novel functions for bacterial polysaccharides in nature, and may lead to the development of new classes of antibiofilm agents for industrial and clinical applications.
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Abstract
Bacterial extracellular polysaccharides have been shown to mediate many of the cell-to-cell and cell-to-surface interactions that are required for the formation, cohesion and stabilization of bacterial biofilms. However, recent studies have identified several bacterial polysaccharides that inhibit biofilm formation by a wide spectrum of bacteria and fungi both in vitro and in vivo. This review discusses the composition, modes of action and potential biological roles of antibiofilm polysaccharides recently identified in bacteria and eukarya. Some of these molecules may have technological applications as antibiofilm agents in industry and medicine.
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Pavlukhina SV, Kaplan JB, Xu L, Chang W, Yu X, Madhyastha S, Yakandawala N, Mentbayeva A, Khan B, Sukhishvili SA. Noneluting enzymatic antibiofilm coatings. ACS APPLIED MATERIALS & INTERFACES 2012; 4:4708-16. [PMID: 22909396 PMCID: PMC3459334 DOI: 10.1021/am3010847] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We developed a highly efficient, biocompatible surface coating that disperses bacterial biofilms through enzymatic cleavage of the extracellular biofilm matrix. The coating was fabricated by binding the naturally existing enzyme dispersin B (DspB) to surface-attached polymer matrices constructed via a layer-by-layer (LbL) deposition technique. LbL matrices were assembled through electrostatic interactions of poly(allylamine hydrochloride) (PAH) and poly(methacrylic acid) (PMAA), followed by chemical cross-linking with glutaraldehyde and pH-triggered removal of PMAA, producing a stable PAH hydrogel matrix used for DspB loading. The amount of DspB loaded increased linearly with the number of PAH layers in surface hydrogels. DspB was retained within these coatings in the pH range from 4 to 7.5. DspB-loaded coatings inhibited biofilm formation by two clinical strains of Staphylococcus epidermidis. Biofilm inhibition was ≥98% compared to mock-loaded coatings as determined by CFU enumeration. In addition, DspB-loaded coatings did not inhibit attachment or growth of cultured human osteoblast cells. We suggest that the use of DspB-loaded multilayer coatings presents a promising method for creating biocompatible surfaces with high antibiofilm efficiency, especially when combined with conventional antimicrobial treatment of dispersed bacteria.
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Kaplan JB, Jabbouri S, Sadovskaya I. Extracellular DNA-dependent biofilm formation by Staphylococcus epidermidis RP62A in response to subminimal inhibitory concentrations of antibiotics. Res Microbiol 2011; 162:535-41. [PMID: 21402153 DOI: 10.1016/j.resmic.2011.03.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 02/25/2011] [Indexed: 10/18/2022]
Abstract
We measured the ability of Staphylococcus epidermidis to form biofilms in the presence of subminimal inhibitory concentrations (sub-MICs) of vancomycin, tigecycline, linezolid and novobiocin. Six strains that produce different amounts of biofilm were tested. The three strains that produced the highest amounts of biofilm exhibited steady-state or decreased biofilm formation in the presence of sub-MIC antibiotics, whereas the three strains that produced lower amounts of biofilm exhibited up to 10-fold-increased biofilm formation in the presence of sub-MIC antibiotics. In two of the inducible strains (9142 and 456a), antibiotic-induced biofilm formation was inhibited by dispersin B, an enzyme that degrades poly-N-acetylglucosamine (PNAG) biofilm polysaccharide. In the third inducible strain (RP62A), dispersin B inhibited biofilm formation in response to sub-MIC vancomycin, but not to sub-MIC tigecycline. In contrast, DNase I efficiently inhibited biofilm formation by strain RP62A in response to sub-MIC tigecycline and vancomycin. DNase I had no effect on antibiotic-induced biofilm formation in strains 9142 and 456a. Our findings indicate that antibiotic-induced biofilm formation in S. epidermidis is both strain- and antibiotic-dependent and that S. epidermidis RP62A utilizes an extracellular DNA-dependent mechanism to form biofilms in response to sub-MIC antibiotics.
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Lee JH, Wang H, Kaplan JB, Lee WY. Microfluidic Approach to Create Three-Dimensional Tissue Models for Biofilm-Related Infection of Orthopaedic Implants. Tissue Eng Part C Methods 2011; 17:39-48. [DOI: 10.1089/ten.tec.2010.0285] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Lee JH, Wang H, Kaplan JB, Lee WY. Effects of Staphylococcus epidermidis on osteoblast cell adhesion and viability on a Ti alloy surface in a microfluidic co-culture environment. Acta Biomater 2010; 6:4422-9. [PMID: 20573556 DOI: 10.1016/j.actbio.2010.05.021] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 04/28/2010] [Accepted: 05/21/2010] [Indexed: 11/17/2022]
Abstract
A microfluidic device was used for real time imaging of MC3T3-E1 murine calvarial pre-osteoblasts (osteoblasts) in response to very small numbers of Staphylococcus epidermidis inoculated on the surface of a polished TiAl6V4 alloy in a serum-based medium. The Ti alloy surface was integrated to a poly(dimethylsiloxane) fluidic housing with eight 10 μl channels for high-throughput, cross-contamination-free co-culture. In the absence of S. epidermidis osteoblasts were able to adhere, spread, proliferate and remain viable on the Ti alloy surface during a 25 h culture period. With 10(2) or 10(5) colony forming units (cfu) ml(-1) S. epidermidis inoculated on the alloy surface osteoblast adhesion, spreading and proliferation were not adversely affected during the early stages of culture. However, osteoblasts became damaged by the end of culture, as S. epidermidis actively proliferated in the co-culture channels and formed small clusters on the alloy surface. These observations suggest that the small numbers of S. epidermidis did not necessarily compete with osteoblasts for the alloy surface during initial host cell development, but rapid proliferation of the bacteria might have changed the microenvironment, making it unfavorable to sustain the viability of osteoblasts. The results provide a new insight in projecting the potential utility of the microfluidic co-culture approach to developing physiologically and clinically relevant in vitro models of orthopedic implant-associated bacterial infection.
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Malo MS, Alam SN, Mostafa G, Zeller SJ, Johnson PV, Mohammad N, Chen KT, Moss AK, Ramasamy S, Faruqui A, Hodin S, Malo PS, Ebrahimi F, Biswas B, Narisawa S, Millán JL, Warren HS, Kaplan JB, Kitts CL, Hohmann EL, Hodin RA. Intestinal alkaline phosphatase preserves the normal homeostasis of gut microbiota. Gut 2010; 59:1476-84. [PMID: 20947883 DOI: 10.1136/gut.2010.211706] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS The intestinal microbiota plays a critical role in maintaining human health; however, the mechanisms governing the normal homeostatic number and composition of these microbes are largely unknown. Previously it was shown that intestinal alkaline phosphatase (IAP), a small intestinal brush border enzyme, functions as a gut mucosal defence factor limiting the translocation of gut bacteria to mesenteric lymph nodes. In this study the role of IAP in the preservation of the normal homeostasis of the gut microbiota was investigated. METHODS Bacterial culture was performed in aerobic and anaerobic conditions to quantify the number of bacteria in the stools of wild-type (WT) and IAP knockout (IAP-KO) C57BL/6 mice. Terminal restriction fragment length polymorphism, phylogenetic analyses and quantitative real-time PCR of subphylum-specific bacterial 16S rRNA genes were used to determine the compositional profiles of microbiotas. Oral supplementation of calf IAP (cIAP) was used to determine its effects on the recovery of commensal gut microbiota after antibiotic treatment and also on the colonisation of pathogenic bacteria. RESULTS IAP-KO mice had dramatically fewer and also different types of aerobic and anaerobic microbes in their stools compared with WT mice. Oral supplementation of IAP favoured the growth of commensal bacteria, enhanced restoration of gut microbiota lost due to antibiotic treatment and inhibited the growth of a pathogenic bacterium (Salmonella typhimurium). CONCLUSIONS IAP is involved in the maintenance of normal gut microbial homeostasis and may have therapeutic potential against dysbiosis and pathogenic infections.
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Fine DH, Kaplan JB, Furgang D, Karched M, Velliyagounder K, Yue G. Mapping the epithelial-cell-binding domain of the Aggregatibacter actinomycetemcomitans autotransporter adhesin Aae. MICROBIOLOGY-SGM 2010; 156:3412-3420. [PMID: 20688817 PMCID: PMC3090143 DOI: 10.1099/mic.0.037606-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The Gram-negative periodontopathogen Aggregatibacter actinomycetemcomitans (Aa) binds selectively to buccal epithelial cells (BECs) of human and Old World primates by means of the outer-membrane autotransporter protein Aae. We speculated that the exposed N-terminal portion of the passenger domain of Aae would mediate binding to BECs. By using a series of plasmids that express full-length or truncated Aae proteins in Escherichia coli, we found that the BEC-binding domain of Aae was located in the N-terminal surface-exposed region of the protein, specifically in the region spanning amino acids 201–284 just upstream of the repeat region within the passenger domain. Peptides corresponding to amino acids 201–221, 222–238 and 201–240 were synthesized and tested for their ability to reduce Aae-mediated binding to BECs based on results obtained with truncated Aae proteins expressed in E. coli. BEC-binding of E. coli expressing Aae was reduced by as much as 50 % by pre-treatment of BECs with a 40-mer peptide (201–240; P40). Aae was also shown to mediate binding to cultured human epithelial keratinocytes (TW2.6), OBA9 and TERT, and endothelial (HUVEC) cells. Pre-treatment of epithelial cells with P40 resulted in a dose-dependent reduction in binding and reduced the binding of both full-length and truncated Aae proteins expressed in E. coli, as well as Aae expressed in Aa. Fluorescently labelled P40 peptides reacted in a dose-dependent manner with BEC receptors. We propose that these proof-of-principle experiments demonstrate that peptides can be designed to interfere with Aa binding mediated by host-cell receptors specific for Aae adhesins.
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Kaplan JB. Biofilm dispersal: mechanisms, clinical implications, and potential therapeutic uses. J Dent Res 2010; 89:205-18. [PMID: 20139339 DOI: 10.1177/0022034509359403] [Citation(s) in RCA: 479] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Like all sessile organisms, surface-attached communities of bacteria known as biofilms must release and disperse cells into the environment to colonize new sites. For many pathogenic bacteria, biofilm dispersal plays an important role in the transmission of bacteria from environmental reservoirs to human hosts, in horizontal and vertical cross-host transmission, and in the exacerbation and spread of infection within a host. The molecular mechanisms of bacterial biofilm dispersal are only beginning to be elucidated. Biofilm dispersal is a promising area of research that may lead to the development of novel agents that inhibit biofilm formation or promote biofilm cell detachment. Such agents may be useful for the prevention and treatment of biofilms in a variety of industrial and clinical settings. This review describes the current status of research on biofilm dispersal, with an emphasis on studies aimed to characterize dispersal mechanisms, and to identify environmental cues and inter- and intracellular signals that regulate the dispersal process. The clinical implications of biofilm dispersal and the potential therapeutic applications of some of the most recent findings will also be discussed.
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Ra SH, Kaplan JB, Lassman CR. Focal nodular hyperplasia after orthotopic liver transplantation. Liver Transpl 2010; 16:98-103. [PMID: 19866450 DOI: 10.1002/lt.21956] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Focal nodular hyperplasia (FNH) has been well characterized in native livers, but to our knowledge, no cases of FNH have been described in liver allografts. We review the clinicopathological features of 6 FNHs identified in 4 patients after orthotopic liver transplantation. There were 3 male patients and 1 female patient ranging in age from 2 to 63 years. The time from transplant to a diagnosis of FNH ranged from 15 to 118 months. Two patients presented with an incidental solitary liver nodule. One patient presented with 2 liver nodules, and the other patient initially presented with 1 liver nodule and was found to have another nodule at autopsy 6 years later. Two FNHs were seen as an incidental finding at autopsy, and the other 4 were initially identified on ultrasound. Follow-up magnetic resonance imaging and computed tomography scans revealed features atypical for FNH and suspicious for hepatocellular carcinoma. The initial diagnosis of FNH was made by needle core biopsy in 3 cases and at autopsy in 2 cases. The lesions ranged in size from 1.7 to 6.9 cm. Three patients had conditions associated with altered hepatic vascular perfusion; 2 patients had portal vein thrombosis, and 1 had a partial allograft from a living donor. In conclusion, FNH can present as a hepatic nodule after orthotopic liver transplantation and should not be confused with hepatocellular carcinoma. Because of altered hepatic circulation in the posttransplant liver, a diagnosis of FNH would not be unexpected. FNH should be considered in the differential diagnosis of hepatic nodules within the posttransplant liver, especially in patients with known hepatic vascular perfusion abnormalities.
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Yakandawala N, Gawande PV, LoVetri K, Romeo T, Kaplan JB, Madhyastha S. Enhanced expression of engineered ACA-less beta-1, 6-N-acetylglucosaminidase (dispersin B) in Escherichia coli. J Ind Microbiol Biotechnol 2009; 36:1297-305. [PMID: 19597857 DOI: 10.1007/s10295-009-0613-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Accepted: 06/19/2009] [Indexed: 11/28/2022]
Abstract
beta-1,6-N-Acetylglucosaminidase (dispersin B), which cleaves poly-ss-(1,6)-linked N-acetylglucosamine, is encoded by dspB of Aggregatibacter actinomycetemcomitans. To enhance the production of dispersin B, we engineered dspB to transcribe mRNAs devoid of the trinucleotide ACA. Transcription and translation levels of ACA-less and wild-type dspB expressed in Escherichia coli (E. coli) under T5 and T7 promoters were analyzed by real-time RT-PCR and protein quantification, respectively. The ACA-less dspB mRNA level was significantly higher (P < 0.01) and produced 77.6 and 34.9% more dispersin B than wild-type dspB expressed under T7 and T5 promoters, respectively. Dispersin B expression under T7 promoter caused a 98-99.5% drop in the glyceraldehyde-3-phosphate dehydrogenase (gapA) mRNA level, which was not observed with T5 promoter. Fusion of green fluorescent protein (GFP) with dispersin B allowed rapid quantification of dispersin B production by measuring fluorescence intensity in culture broth. Although the cultures containing 0.1% glucose showed sustained increase in dispersin B-GFP production until 12 h, no significant increase in dispersin B activity was observed beyond 4 and 6 h after induction when expressed under T7 and T5 promoters, respectively. This study demonstrates the effectiveness of ACA-less mRNA and the advantage of GFP tagging for enhanced dispersin B production and quantification, which could be adapted for improving the production of other commercially important proteins in E. coli.
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