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Chamlagain M, Hu J, Sionov RV, Steinberg D. Anti-bacterial and anti-biofilm activities of arachidonic acid against the cariogenic bacterium Streptococcus mutans. Front Microbiol 2024; 15:1333274. [PMID: 38596377 PMCID: PMC11002910 DOI: 10.3389/fmicb.2024.1333274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 02/16/2024] [Indexed: 04/11/2024] Open
Abstract
Streptococcus mutans is a Gram-positive, facultative anaerobic bacterium, which causes dental caries after forming biofilms on the tooth surface while producing organic acids that demineralize enamel and dentin. We observed that the polyunsaturated arachidonic acid (AA) (ω-6; 20:4) had an anti-bacterial activity against S. mutans, which prompted us to investigate its mechanism of action. The minimum inhibitory concentration (MIC) of AA on S. mutans was 25 μg/ml in the presence of 5% CO2, while it was reduced to 6.25-12.5 μg/ml in the absence of CO2 supplementation. The anti-bacterial action was due to a combination of bactericidal and bacteriostatic effects. The minimum biofilm inhibitory concentration (MBIC) was the same as the MIC, suggesting that part of the anti-biofilm effect was due to the anti-bacterial activity. Gene expression studies showed decreased expression of biofilm-related genes, suggesting that AA also has a specific anti-biofilm effect. Flow cytometric analyses using potentiometric DiOC2(3) dye, fluorescent efflux pump substrates, and live/dead SYTO 9/propidium iodide staining showed that AA leads to immediate membrane hyperpolarization, altered membrane transport and efflux pump activities, and increased membrane permeability with subsequent membrane perforation. High-resolution scanning electron microscopy (HR-SEM) showed remnants of burst bacteria. Furthermore, flow cytometric analysis using the redox probe 2',7'-dichlorofluorescein diacetate (DCFHDA) showed that AA acts as an antioxidant in a dose-dependent manner. α-Tocopherol, an antioxidant that terminates the radical chain, counteracted the anti-bacterial activity of AA, suggesting that oxidation of AA in bacteria leads to the production of cytotoxic radicals that contribute to bacterial growth arrest and death. Importantly, AA was not toxic to normal Vero epithelial cells even at 100 μg/ml, and it did not cause hemolysis of erythrocytes. In conclusion, our study shows that AA is a potentially safe drug that can be used to reduce the bacterial burden of cariogenic S. mutans.
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Affiliation(s)
- Manoj Chamlagain
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong SAR, China
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Jieni Hu
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ronit Vogt Sionov
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Doron Steinberg
- Institute of Biomedical and Oral Research (IBOR), The Faculty of Dental Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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Zhu Z, Wu S, Chen X, Tan W, Zou G, Huang Q, Meng X, Hu DL, Li S. Heterogeneity and transmission of food safety-related enterotoxigenic Staphylococcus aureus in pig abattoirs in Hubei, China. Microbiol Spectr 2023; 11:e0191323. [PMID: 37772855 PMCID: PMC10581196 DOI: 10.1128/spectrum.01913-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 08/04/2023] [Indexed: 09/30/2023] Open
Abstract
The dissemination of Staphylococcus aureus in the pork production chain is a major food safety concern. Abattoirs can serve both as disruptor and transmitter for S. aureus. In this study, we conducted a systematic genomic epidemiology research on the prevalence, heterogeneity, and transmission of S. aureus in 3,638 samples collected from four pig abattoirs in Hubei province, China. Our findings revealed substantial heterogeneity between S. aureus recovered from samples collected at upstream (from stunning step to head-removal step) and downstream (from splitting step to chilling step) locations within the slaughter process. Overall, 966 (26.6%) samples were positive for S. aureus, with significantly higher overall prevalence for upstream samples (29.0%, 488/1,681) compared to downstream samples (24.4%, 478/1,957). Antimicrobial susceptibility testing demonstrated that the isolates from the upstream exhibited significantly higher resistance proportions to different antimicrobials than those from the downstream. Whole-genome sequencing of 126 isolates revealed that ST398 (32.9%, 23/70) and ST9 (22.9%, 16/70) were more common among upstream isolates, while ST7 (35.7%, 20/56) and ST97 (28.6%, 16/56) were most frequently observed among downstream isolates. Additionally, molecular characterization analysis demonstrated that upstream isolates possessed significantly higher enterotoxigenic potential, more antimicrobial resistance genes, and S. aureus pathogenicity islands than downstream isolates. Notably, we discovered that enterotoxigenic S. aureus could be transmitted across different slaughter stages, with knives, water, and air serving as vectors. Although slaughtering processes had a substantial effect on reducing the food safety risk posed by enterotoxigenic S. aureus, the possibility of its widespread transmission should not be disregarded. IMPORTANCE Staphylococcus aureus (S. aureus) is one of the most important foodborne pathogens, and can cause foodborne poisoning by producing enterotoxins. Pork is a preferable reservoir and its contamination often occurs during the slaughter process. Our findings revealed significant differences in the prevalence, antimicrobial resistance, and enterotoxigenic potential between the upstream and downstream isolates within the slaughter process. Also, it is imperative not to overlook enterotoxigenic S. aureus transmitted across all stages of the slaughter process, with notable vectors being knives, water, and air. These findings hold significant implications for policy-makers to reassess their surveillance projects, and underscore the importance of implementing effective control measures to minimize the risk of S. aureus contamination in pork production. Moreover, we provide a more compelling method of characterizing pathogen transmission based on core-SNPs of bacterial genomes.
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Affiliation(s)
- Zhihao Zhu
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Simin Wu
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Xingyu Chen
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Wei Tan
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Geng Zou
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Qi Huang
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Xianrong Meng
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Dong-Liang Hu
- Department of Zoonoses, Kitasato University School of Veterinary Medicine, Towada, Japan
| | - Shaowen Li
- Key Laboratory of Preventive Veterinary Medicine in Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
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Li Y, Pan T, Cao R, Li W, He Z, Sun B. Nitrate Reductase NarGHJI Modulates Virulence via Regulation of agr Expression in Methicillin-Resistant Staphylococcus aureus Strain USA300 LAC. Microbiol Spectr 2023; 11:e0359622. [PMID: 37199609 PMCID: PMC10269880 DOI: 10.1128/spectrum.03596-22] [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: 09/06/2022] [Accepted: 04/28/2023] [Indexed: 05/19/2023] Open
Abstract
Staphylococcus aureus is a pathogenic bacterium with a widespread distribution that can cause diverse severe diseases. The membrane-bound nitrate reductase NarGHJI serves respiratory function. However, little is known about its contribution to virulence. In this study, we demonstrated that narGHJI disruption results in the downregulation of virulence genes (e.g., RNAIII, agrBDCA, hla, psmα, and psmβ) and reduces the hemolytic activity of the methicillin-resistant S. aureus (MRSA) strain USA300 LAC. Moreover, we provided evidence that NarGHJI participates in regulating host inflammatory response. A mouse model of subcutaneous abscess and Galleria mellonella survival assay demonstrated that the ΔnarG mutant was significantly less virulent than the wild type. Interestingly, NarGHJI contributes to virulence in an agr-dependent manner, and the role of NarGHJI differs between different S. aureus strains. Our study highlights the novel role of NarGHJI in regulating virulence, thereby providing a new theoretical reference for the prevention and control of S. aureus infection. IMPORTANCE Staphylococcus aureus is a notorious pathogen that poses a great threat to human health. The emergence of drug-resistant strains has significantly increased the difficulty of preventing and treating S. aureus infection and enhanced the pathogenic ability of the bacterium. This indicates the importance of identifying novel pathogenic factors and revealing the regulatory mechanisms through which they regulate virulence. The nitrate reductase NarGHJI is mainly involved in bacterial respiration and denitrification, which can enhance bacterial survival. We demonstrated that narGHJI disruption results in the downregulation of the agr system and agr-dependent virulence genes, suggesting that NarGHJI participates in the regulation of S. aureus virulence in an agr-dependent manner. Moreover, the regulatory approach is strain specific. This study provides a new theoretical reference for the prevention and control of S. aureus infection and reveals new targets for the development of therapeutic drugs.
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Affiliation(s)
- Yujie Li
- Department of Oncology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, People’s Republic of China
- Department of Life Science and Medicine, University of Science and Technology of China, Hefei, People’s Republic of China
| | - Ting Pan
- Department of Oncology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, People’s Republic of China
- Department of Life Science and Medicine, University of Science and Technology of China, Hefei, People’s Republic of China
| | - Ruobing Cao
- Department of Oncology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, People’s Republic of China
- Department of Life Science and Medicine, University of Science and Technology of China, Hefei, People’s Republic of China
| | - Wei Li
- Department of Oncology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, People’s Republic of China
- Department of Life Science and Medicine, University of Science and Technology of China, Hefei, People’s Republic of China
| | - Zhien He
- Department of Oncology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, People’s Republic of China
- Department of Life Science and Medicine, University of Science and Technology of China, Hefei, People’s Republic of China
| | - Baolin Sun
- Department of Oncology, The First Affiliated Hospital, University of Science and Technology of China, Hefei, People’s Republic of China
- Department of Life Science and Medicine, University of Science and Technology of China, Hefei, People’s Republic of China
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Papadopoulou V, Sidders AE, Lu KY, Velez AZ, Durham PG, Bui DT, Angeles-Solano M, Dayton PA, Rowe SE. Overcoming biological barriers to improve treatment of a Staphylococcus aureus wound infection. Cell Chem Biol 2023; 30:513-526.e5. [PMID: 37148883 PMCID: PMC10198964 DOI: 10.1016/j.chembiol.2023.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 01/19/2023] [Accepted: 04/17/2023] [Indexed: 05/08/2023]
Abstract
Chronic wounds frequently become infected with bacterial biofilms which respond poorly to antibiotic therapy. Aminoglycoside antibiotics are ineffective at treating deep-seated wound infections due to poor drug penetration, poor drug uptake into persister cells, and widespread antibiotic resistance. In this study, we combat the two major barriers to successful aminoglycoside treatment against a biofilm-infected wound: limited antibiotic uptake and limited biofilm penetration. To combat the limited antibiotic uptake, we employ palmitoleic acid, a host-produced monounsaturated fatty acid that perturbs the membrane of gram-positive pathogens and induces gentamicin uptake. This novel drug combination overcomes gentamicin tolerance and resistance in multiple gram-positive wound pathogens. To combat biofilm penetration, we examined the ability of sonobactericide, a non-invasive ultrasound-mediated-drug delivery technology to improve antibiotic efficacy using an in vivo biofilm model. This dual approach dramatically improved antibiotic efficacy against a methicillin-resistant Staphylococcus aureus (MRSA) wound infection in diabetic mice.
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Affiliation(s)
- Virginie Papadopoulou
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC 27599, USA.
| | - Ashelyn E Sidders
- Department of Microbiology and Immunology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA
| | - Kuan-Yi Lu
- Department of Microbiology and Immunology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA
| | - Amanda Z Velez
- Department of Microbiology and Immunology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA
| | - Phillip G Durham
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC 27599, USA; Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Duyen T Bui
- Department of Microbiology and Immunology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA
| | - Michelle Angeles-Solano
- Department of Microbiology and Immunology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA
| | - Paul A Dayton
- Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC 27599, USA; Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Sarah E Rowe
- Department of Microbiology and Immunology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA.
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Sidders AE, Kedziora KM, Arts M, Daniel JM, de Benedetti S, Beam JE, Bui DT, Parsons JB, Schneider T, Rowe SE, Conlon BP. Antibiotic-induced accumulation of lipid II synergizes with antimicrobial fatty acids to eradicate bacterial populations. eLife 2023; 12:80246. [PMID: 36876902 PMCID: PMC10030119 DOI: 10.7554/elife.80246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 03/05/2023] [Indexed: 03/07/2023] Open
Abstract
Antibiotic tolerance and antibiotic resistance are the two major obstacles to the efficient and reliable treatment of bacterial infections. Identifying antibiotic adjuvants that sensitize resistant and tolerant bacteria to antibiotic killing may lead to the development of superior treatments with improved outcomes. Vancomycin, a lipid II inhibitor, is a frontline antibiotic for treating methicillin-resistant Staphylococcus aureus and other Gram-positive bacterial infections. However, vancomycin use has led to the increasing prevalence of bacterial strains with reduced susceptibility to vancomycin. Here, we show that unsaturated fatty acids act as potent vancomycin adjuvants to rapidly kill a range of Gram-positive bacteria, including vancomycin-tolerant and resistant populations. The synergistic bactericidal activity relies on the accumulation of membrane-bound cell wall intermediates that generate large fluid patches in the membrane leading to protein delocalization, aberrant septal formation, and loss of membrane integrity. Our findings provide a natural therapeutic option that enhances vancomycin activity against difficult-to-treat pathogens, and the underlying mechanism may be further exploited to develop antimicrobials that target recalcitrant infection.
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Affiliation(s)
- Ashelyn E Sidders
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Katarzyna M Kedziora
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, United States
- Bioinformatics and Analytics Research Collaborative, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Melina Arts
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany
| | - Jan-Martin Daniel
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany
| | | | - Jenna E Beam
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Duyen T Bui
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Joshua B Parsons
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, United States
- Division of Infectious Diseases, Duke University, Durham, United States
| | - Tanja Schneider
- Institute for Pharmaceutical Microbiology, University of Bonn, Bonn, Germany
| | - Sarah E Rowe
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Brian P Conlon
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, United States
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, United States
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Targeting the Holy Triangle of Quorum Sensing, Biofilm Formation, and Antibiotic Resistance in Pathogenic Bacteria. Microorganisms 2022; 10:microorganisms10061239. [PMID: 35744757 PMCID: PMC9228545 DOI: 10.3390/microorganisms10061239] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 06/12/2022] [Accepted: 06/14/2022] [Indexed: 12/12/2022] Open
Abstract
Chronic and recurrent bacterial infections are frequently associated with the formation of biofilms on biotic or abiotic materials that are composed of mono- or multi-species cultures of bacteria/fungi embedded in an extracellular matrix produced by the microorganisms. Biofilm formation is, among others, regulated by quorum sensing (QS) which is an interbacterial communication system usually composed of two-component systems (TCSs) of secreted autoinducer compounds that activate signal transduction pathways through interaction with their respective receptors. Embedded in the biofilms, the bacteria are protected from environmental stress stimuli, and they often show reduced responses to antibiotics, making it difficult to eradicate the bacterial infection. Besides reduced penetration of antibiotics through the intricate structure of the biofilms, the sessile biofilm-embedded bacteria show reduced metabolic activity making them intrinsically less sensitive to antibiotics. Moreover, they frequently express elevated levels of efflux pumps that extrude antibiotics, thereby reducing their intracellular levels. Some efflux pumps are involved in the secretion of QS compounds and biofilm-related materials, besides being important for removing toxic substances from the bacteria. Some efflux pump inhibitors (EPIs) have been shown to both prevent biofilm formation and sensitize the bacteria to antibiotics, suggesting a relationship between these processes. Additionally, QS inhibitors or quenchers may affect antibiotic susceptibility. Thus, targeting elements that regulate QS and biofilm formation might be a promising approach to combat antibiotic-resistant biofilm-related bacterial infections.
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