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Sharma P, Vaiwala R, Gopinath AK, Chockalingam R, Ayappa KG. Structure of the Bacterial Cell Envelope and Interactions with Antimicrobials: Insights from Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:7791-7811. [PMID: 38451026 DOI: 10.1021/acs.langmuir.3c03474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Bacteria have evolved over 3 billion years, shaping our intrinsic and symbiotic coexistence with these single-celled organisms. With rising populations of drug-resistant strains, the search for novel antimicrobials is an ongoing area of research. Advances in high-performance computing platforms have led to a variety of molecular dynamics simulation strategies to study the interactions of antimicrobial molecules with different compartments of the bacterial cell envelope of both Gram-positive and Gram-negative species. In this review, we begin with a detailed description of the structural aspects of the bacterial cell envelope. Simulations concerned with the transport and associated free energy of small molecules and ions through the outer membrane, peptidoglycan, inner membrane and outer membrane porins are discussed. Since surfactants are widely used as antimicrobials, a section is devoted to the interactions of surfactants with the cell wall and inner membranes. The review ends with a discussion on antimicrobial peptides and the insights gained from the molecular simulations on the free energy of translocation. Challenges involved in developing accurate molecular models and coarse-grained strategies that provide a trade-off between atomic details with a gain in sampling time are highlighted. The need for efficient sampling strategies to obtain accurate free energies of translocation is also discussed. Molecular dynamics simulations have evolved as a powerful tool that can potentially be used to design and develop novel antimicrobials and strategies to effectively treat bacterial infections.
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Affiliation(s)
- Pradyumn Sharma
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - Rakesh Vaiwala
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - Amar Krishna Gopinath
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - Rajalakshmi Chockalingam
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - K Ganapathy Ayappa
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
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Jiang F, Wang J, Ren Z, Hu Y, Wang B, Li M, Yu J, Tang J, Guo G, Cheng Y, Han P, Shen H. Targeted Light-Induced Immunomodulatory Strategy for Implant-Associated Infections via Reversing Biofilm-Mediated Immunosuppression. ACS NANO 2024; 18:6990-7010. [PMID: 38385433 DOI: 10.1021/acsnano.3c10172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
The clinical treatment efficacy for implant-associated infections (IAIs), particularly those caused by Methicillin-resistant Staphylococcus aureus (MRSA), remains unsatisfactory, primarily due to the formation of biofilm barriers and the resulting immunosuppressive microenvironment, leading to the chronicity and recurrence of IAIs. To address this challenge, we propose a light-induced immune enhancement strategy, synthesizing BSA@MnO2@Ce6@Van (BMCV). The BMCV exhibits precise targeting and adhesion to the S. aureus biofilm-infected region, coupled with its capacity to catalyze oxygen generation from H2O2 in the hypoxic and acidic biofilm microenvironment (BME), promoting oxygen-dependent photodynamic therapy efficacy while ensuring continuous release of manganese ions. Notably, targeted BMCV can penetrate biofilms, producing ROS that degrade extracellular DNA, disrupting the biofilm structure and impairing its barrier function, making it vulnerable to infiltration and elimination by the immune system. Furthermore, light-induced reactive oxygen species (ROS) around the biofilm can lyse S. aureus, triggering bacterium-like immunogenic cell death (ICD), releasing abundant immune costimulatory factors, facilitating the recognition and maturation of antigen-presenting cells (APCs), and activating adaptive immunity. Additionally, manganese ions in the BME act as immunoadjuvants, further amplifying macrophage-mediated innate and adaptive immune responses and reversing the immunologically cold BME to an immunologically hot BME. We prove that our synthesized BMCV elicits a robust adaptive immune response in vivo, effectively clearing primary IAIs and inducing long-term immune memory to prevent recurrence. Our study introduces a potent light-induced immunomodulatory nanoplatform capable of reversing the biofilm-induced immunosuppressive microenvironment and disrupting biofilm-mediated protective barriers, offering a promising immunotherapeutic strategy for addressing challenging S. aureus IAIs.
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Affiliation(s)
- Feng Jiang
- Department of Orthopedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Jian Wang
- Department of Interventional Radiology, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Zun Ren
- Department of Orthopedics, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Yujie Hu
- Department of Orthopedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Boyong Wang
- Department of Orthopedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Mingzhang Li
- Department of Orthopedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Jinlong Yu
- Department of Orthopedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Jin Tang
- Department of Clinical Laboratory, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Geyong Guo
- Department of Orthopedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Yingsheng Cheng
- Department of Interventional Radiology, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
- Department of Imaging Medicine and Nuclear Medicine, Tongji Hospital, Shanghai 200065, China
| | - Pei Han
- Department of Orthopedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Hao Shen
- Department of Orthopedics, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
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Trzebny A, Slodkowicz-Kowalska A, Björkroth J, Dabert M. Microsporidian Infection in Mosquitoes (Culicidae) Is Associated with Gut Microbiome Composition and Predicted Gut Microbiome Functional Content. MICROBIAL ECOLOGY 2023; 85:247-263. [PMID: 34939130 PMCID: PMC9849180 DOI: 10.1007/s00248-021-01944-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 12/10/2021] [Indexed: 06/14/2023]
Abstract
The animal gut microbiota consist of many different microorganisms, mainly bacteria, but archaea, fungi, protozoans, and viruses may also be present. This complex and dynamic community of microorganisms may change during parasitic infection. In the present study, we investigated the effect of the presence of microsporidians on the composition of the mosquito gut microbiota and linked some microbiome taxa and functionalities to infections caused by these parasites. We characterised bacterial communities of 188 mosquito females, of which 108 were positive for microsporidian DNA. To assess how bacterial communities change during microsporidian infection, microbiome structures were identified using 16S rRNA microbial profiling. In total, we identified 46 families and four higher taxa, of which Comamonadaceae, Enterobacteriaceae, Flavobacteriaceae and Pseudomonadaceae were the most abundant mosquito-associated bacterial families. Our data suggest that the mosquito gut microbial composition varies among host species. In addition, we found a correlation between the microbiome composition and the presence of microsporidians. The prediction of metagenome functional content from the 16S rRNA gene sequencing suggests that microsporidian infection is characterised by some bacterial species capable of specific metabolic functions, especially the biosynthesis of ansamycins and vancomycin antibiotics and the pentose phosphate pathway. Moreover, we detected a positive correlation between the presence of microsporidian DNA and bacteria belonging to Spiroplasmataceae and Leuconostocaceae, each represented by a single species, Spiroplasma sp. PL03 and Weissella cf. viridescens, respectively. Additionally, W. cf. viridescens was observed only in microsporidian-infected mosquitoes. More extensive research, including intensive and varied host sampling, as well as determination of metabolic activities based on quantitative methods, should be carried out to confirm our results.
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Affiliation(s)
- Artur Trzebny
- Molecular Biology Techniques Laboratory, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland.
| | - Anna Slodkowicz-Kowalska
- Department of Biology and Medical Parasitology, Poznan University of Medical Sciences, Poznan, Poland
| | - Johanna Björkroth
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Miroslawa Dabert
- Molecular Biology Techniques Laboratory, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
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Chen M, Li Y, Hou WX, Peng DY, Li JK, Zhang HX. The Antibacterial Effect, Biocompatibility, and Osteogenesis of Vancomycin-Nanodiamond Composite Scaffold for Infected Bone Defects. Int J Nanomedicine 2023; 18:1365-1380. [PMID: 36974073 PMCID: PMC10039664 DOI: 10.2147/ijn.s397316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 03/02/2023] [Indexed: 03/29/2023] Open
Abstract
Purpose The repair and treatment of infected bone defects (IBD) is a common challenge faced by orthopedic clinics, medical materials science, and tissue engineering. Methods Based on the treatment requirements of IBD, we utilized multidisciplinary knowledge from clinical medicine, medical materials science, and tissue engineering to construct a high-efficiency vancomycin sustained-release system with nanodiamond (ND) and prepare a composite scaffold. Its effect on IBD treatment was assessed from materials, cytology, bacteriology, and zoology perspectives. Results The results demonstrated that the Van-ND-45S5 scaffold exhibited an excellent antibacterial effect, biocompatibility, and osteogenesis in vitro. Moreover, an efficient animal model of IBD was established, and a Van-ND-45S5 scaffold was implanted into the IBD. Radiographic and histological analyses and bone repair-related protein expression, confirmed that the Van-ND-45S5 scaffold had good biocompatibility and osteogenic and anti-infective activities in vivo. Conclusion Collectively, our findings support that the Van-ND-45S5 scaffold is a promising new material and approach for treating IBD with good antibacterial effects, biocompatibility, and osteogenesis.
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Affiliation(s)
- Meng Chen
- Department of Orthopedic Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong Province, 250014, People’s Republic of China
- Department of Orthopedic Surgery, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong Province, 250014, People’s Republic of China
| | - Yang Li
- Department of Orthopedic Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong Province, 250014, People’s Republic of China
- Department of Orthopedic Surgery, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong Province, 250014, People’s Republic of China
| | - Wen-Xiu Hou
- Department of Spine Surgery, Shandong University Qilu Hospital, Jinan, Shandong, 250000, People’s Republic of China
| | - Da-Yong Peng
- Department of Orthopedic Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong Province, 250014, People’s Republic of China
- Department of Orthopedic Surgery, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong Province, 250014, People’s Republic of China
| | - Jing-Kun Li
- Department of Orthopedic Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong Province, 250014, People’s Republic of China
- Department of Orthopedic Surgery, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong Province, 250014, People’s Republic of China
| | - Hao-Xuan Zhang
- Department of Orthopedic Surgery, The First Affiliated Hospital of Shandong First Medical University, Jinan, Shandong Province, 250014, People’s Republic of China
- Department of Orthopedic Surgery, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong Province, 250014, People’s Republic of China
- Correspondence: Hao-Xuan Zhang, Department of Orthopedics, The First Affiliated Hospital of Shandong First Medical University, No. 16766, Lixia District, Jingshi Road, Jinan, Shandong Province, 250014, People’s Republic of China, Tel/Fax +86531-89268540, Email
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Lian Q, Zheng S, Shi Z, Li K, Chen R, Wang P, Liu H, Chen Y, Zhong Q, Liu Q, Pan X, Gao J, Gao C, Liu W, Wu X, Zhang Y, Zhang Y, Wang J, Cheng H. Using a degradable three-layer sandwich-type coating to prevent titanium implant infection with the combined efficient bactericidal ability and fast immune remodeling property. Acta Biomater 2022; 154:650-666. [PMID: 36306986 DOI: 10.1016/j.actbio.2022.10.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 09/18/2022] [Accepted: 10/14/2022] [Indexed: 01/24/2023]
Abstract
Titanium (Ti) implant-associated infections are a challenge in orthopedic surgery, for which a series of antibacterial coatings have been designed and fabricated to reduce the risk of bacterial contamination. Herein, we created a degradable three-layer sandwich-type coating to achieve long-term antibacterial effects while simultaneously reconstructing the local immune microenvironment. The vancomycin (Van)-loaded vaterite coating constitutes the outer and inner layers, whereas Interleukin-12 (IL-12)-containing liposomes embedded in sodium alginate constitutes the middle layer. Van, released from the vaterite, demonstrated a favorable and rapid bactericidal ability against the representative methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains. The released IL-12 exhibited the desired immune reconstitution abilities, actively facilitating defenses against subsequent bacterial invasions. Furthermore, the biocompatibility and cell-binding feature of the multifunctional coating was beneficial for achieving solid interface intergradation. Overall, the benefits of the three-layer sandwich-type coating, including the convenient fabrication process, efficient antimicrobial activity, fast immune remodeling property, fine cell-binding feature, and biodegradability, highlight its promising translational potential in preventing implant infection. STATEMENT OF SIGNIFICANCE: To prevent titanium implant infections, researchers have designed various antibacterial coatings. However, most of these coatings focused only on killing the invading bacteria over a limited postoperative period. However, the local immune microenvironment is compromised during surgery. Local immune deflection impedes the ability of the local immune defenses to clear bacteria and limits immune memory building from active defense against long-term subsequent bacterial invasions. Furthermore, these coatings are usually nondegradable and differ substantially from bone components, thereby impairing the integration of the coating and bone interface and generating concerns about implant stability and bacterial contamination. In this work, we synthesized a degradable coating that provides sustained antibacterial activity, promotes immune reconstitution, and simultaneously achieves solid bone integration.
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Affiliation(s)
- Qiang Lian
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Shaowei Zheng
- Department of Orthopedic, Huizhou First Hospital, Guangdong Medical University, Huizhou 516003, China; Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Zhe Shi
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Kangxian Li
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Rong Chen
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Pinkai Wang
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Haibing Liu
- Department of Orthopedic, Affiliated Hengyang Hospital, Southern Medical University (Hengyang Central Hospital), Hengyang 421001, China
| | - Yuhang Chen
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Qiang Zhong
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Qi Liu
- South China Advanced Institute for Soft Matter Science and Technology, South China University of Technology, Guangzhou 510640, China
| | - Xin Pan
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Jian Gao
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Chenghao Gao
- Department of Orthopedic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 43000, China
| | - Weilu Liu
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Xuanpin Wu
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Yayun Zhang
- Department of Orthopedic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 43000, China
| | - Yang Zhang
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
| | - Jian Wang
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
| | - Hao Cheng
- Department of Orthopedic, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
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Olademehin OP, Shuford KL, Kim SJ. Molecular dynamics simulations of the secondary-binding site in disaccharide-modified glycopeptide antibiotics. Sci Rep 2022; 12:7087. [PMID: 35490171 PMCID: PMC9056522 DOI: 10.1038/s41598-022-10735-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/12/2022] [Indexed: 11/16/2022] Open
Abstract
Oritavancin is a semisynthetic glycopeptide antibiotic used to treat severe infections by multidrug-resistant Gram-positive pathogens. Oritavancin is known to be a thousand times more potent than vancomycin against Gram-positive bacteria due to the additional interactions with bacterial peptidoglycan (PG) facilitated by a secondary-binding site. The presence of this secondary-binding site is evident in desleucyl-oritavancin, an Edman degradation product of oritavancin, still retaining its potency against Gram-positive bacteria, whereas desleucyl-vancomycin is devoid of any antimicrobial activities. Herein, using explicit solvent molecular dynamics (MD) simulations, steered MD simulations, and umbrella sampling, we show evidence of a secondary-binding site mediated by the disaccharide-modified hydrophobic sidechain of oritavancin interactions with the pentaglycyl-bridge segment of the PG. The interactions were characterized through comparison to the interaction of PG with chloroeremomycin, vancomycin, and the desleucyl analogs of the glycopeptides. Our results show that the enhanced binding of oritavancin to PG over the binding of the other complexes studied is due to an increase in the hydrophobic effect, electrostatic and van der Waals interactions, and not the average number of hydrogen bonds. Our ranking of the binding interactions of the biomolecular complexes directly correlates with the order based on their experimental minimum inhibitory concentrations. The results of our simulations provide insight into the modification of glycopeptides to increase their antimicrobial activities or the design of novel antibiotics against pathogenic Gram-positive bacteria.
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Affiliation(s)
| | - Kevin L Shuford
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76706, USA.
| | - Sung J Kim
- Department of Chemistry, Howard University, Washington, DC, 20059, USA.
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Ahmad N, Singh A, Gupta A, Pant P, Singh TP, Sharma S, Sharma P. Discovery of the Lead Molecules Targeting the First Step of the Histidine Biosynthesis Pathway of Acinetobacter baumannii. J Chem Inf Model 2022; 62:1744-1759. [PMID: 35333517 DOI: 10.1021/acs.jcim.1c01421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Acinetobacter baumannii is a multidrug-resistant, opportunistic, nosocomial pathogen for which a new line of treatments is desperately needed. We have targeted the enzyme of the first step of the histidine biosynthesis pathway, viz., ATP-phosphoribosyltransferase (ATP-PRT). The three-dimensional structure of ATP-PRT was predicted on the template of the known three-dimensional structure of ATP-PRT from Psychrobacter arcticus (PaATPPRT) using a homology modeling approach. High-throughput virtual screening (HTVS) of the antibacterial library of Life Chemicals Inc., Ontario, Canada was carried out followed by molecular dynamics simulations of the top hit compounds. In silico results were then biochemically validated using surface plasmon resonance spectroscopy. We found that two compounds, namely, F0843-0019 and F0608-0626, were binding with micromolar affinities to the ATP-phosphoribosyltransferase from Acinetobacter baumannii (AbATPPRT). Both of these compounds were binding in the same way as AMP in PaATPPRT, and the important residues of the active site, viz., Val4, Ser72, Thr76, Tyr77, Glu95, Lys134, Val136, and Tyr156, were also interacting via hydrogen bonds. The calculated binding energies of these compounds were -10.5 kcal/mol and -11.1 kcal/mol, respectively. These two compounds can be used as the potential lead molecules for designing antibacterial compounds in the future, and this information will help in drug discovery programs against Acinetobacter worldwide.
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Affiliation(s)
- Nabeel Ahmad
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Anamika Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Akshita Gupta
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Pradeep Pant
- Department of Chemistry, Indian Institute of Technology, Delhi 110016, India
| | - Tej P Singh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Sujata Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Pradeep Sharma
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
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GVPC Medium Manufactured without Oxygen Improves the Growth of Legionella spp. and Exhibits Enhanced Selectivity Properties. Microbiol Spectr 2022; 10:e0240121. [PMID: 35315693 PMCID: PMC9045360 DOI: 10.1128/spectrum.02401-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycine-vancomycin-polymyxin-cycloheximide agar (GVPC) is a recommended medium for the detection of Legionella spp. in water samples. However, its quality could be improved in terms of recovery of Legionella spp. and selectivity properties. Modifications were introduced in GVPC manufacture: autoclaving conditions (115°C, 15 min) and atmosphere during component-stirring (removal of oxygen and N2 injection). The use of softer autoclaving conditions (115°C, 15 min) improved the growth of Legionella anisa by the spiral method and Legionella pneumophila after membrane filtration. The medium manufactured with O2 removal and autoclaving for 15 min at 115°C allowed a faster growth of L. pneumophila (colonies visible at day 2) and a notable increase of L. anisa growth (colonies appearing at day 3, and statistically significant numbers of CFU at day 5). After 3 to 5 days of incubation, the improved media showed higher selectivity properties, particularly for Enterococcus faecalis ATCC 29212 and Pseudomonas aeruginosa ATCC 9027. A further improvement was achieved by the addition of N2 during ingredient stirring, leading to a statistically significant faster growth of L. pneumophila at days 2 and 3 and L. anisa at day 3. Selectivity properties were also enhanced, resulting in the complete inhibition of both E. faecalis strains and Escherichia coli and complete-partial inhibition of P. aeruginosa. Oxygen removal during GVPC manufacture using a vacuum pump system promotes the growth of L. pneumophila and L. anisa, and markedly inhibits the growth of E. coli, P. aeruginosa, and E. faecalis. IMPORTANCE Currently, GVPC is a recommended medium for the detection of Legionella spp. in water samples. However, recovery of Legionella spp. and selectivity properties can be improved. GVPC medium manufactured without oxygen improved the growth of Legionella pneumophila and Legionella anisa. Oxygen removal during GVPC manufacture also improved selectivity properties. A further improvement was achieved by the addition of N2 during ingredient stirring, leading to a faster growth of L. pneumophila at days 2 and 3 and L. anisa at day 3 and enhancement of selectivity properties. The introduction of the modified GVPC medium in routine practice can allow a better detection of Legionella spp. in water samples.
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Jin T, Long F, Zhang Q, Zhuang W. Site-Specific Water Dynamics in the First Hydration Layer of an Anti-Freeze Glyco-Protein: A Simulation Study. Phys Chem Chem Phys 2022; 24:21165-21177. [DOI: 10.1039/d2cp00883a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Antifreeze glycoproteins (AFGPs) inhibit ice recrystallization by a mechanism remaining largely elusive. Dynamics of AFGPs’ hydration water and its involvement in the antifreeze activity, for instance, have not been identified...
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