A Comparison of Effects of Broad-Spectrum Antibiotics and Biosurfactants on Established Bacterial Biofilms (original) (raw)
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Zentralblatt für Bakteriologie : international journal of medical microbiology, 1999
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Biofilm refers to the complex, sessile communities of microbes found either attached to a surface or buried firmly in an extracellular matrix as aggregates. The biofilm matrix surrounding bacteria makes them tolerant to harsh conditions and resistant to antibacterial treatments. Moreover, the biofilms are responsible for causing a broad range of chronic diseases and due to the emergence of antibiotic resistance in bacteria it has really become difficult to treat them with efficacy. Furthermore, the antibiotics available till date are ineffective for treating these biofilm related infections due to their higher values of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), which may result in in-vivo toxicity. Hence, it is critically important to design or screen anti-biofilm molecules that can effectively minimize and eradicate biofilm related infections. In the present article, we have highlighted the mechanism of biofilm formation with reference to different models and various methods used for biofilm detection. A major focus has been put on various anti-biofilm molecules discovered or tested till date which may include herbal active compounds, chelating agents, peptide antibiotics, lantibiotics and synthetic chemical compounds along with their structures, mechanism of action and their respective MICs, MBCs, minimum biofilm inhibitory concentrations (MBICs) as well as the half maximal inhibitory concentration (IC 50) values available in the literature so far. Different mode of action of anti biofilm molecules addressed here are inhibition via interference in the quorum sensing pathways, adhesion mechanism, disruption of extracellular DNA, protein, lipopolysaccharides, exopolysaccharides and secondary messengers involved in various signaling pathways. From this study, we conclude that the molecules considered here might be used to treat biofilm-associated infections after significant structural modifications, thereby investigating its effective delivery in the host. It should also be ensured that minimum effective concentration of these molecules must be capable of eradicating biofilm infections with maximum potency without posing any adverse side effects on the host.
Control of Biofilm Formation: Antibiotics and Beyond
Applied and Environmental Microbiology, 2016
Biofilm-associated bacteria are less sensitive to antibiotics than free-living (planktonic) cells. Furthermore, with variations in the concentration of antibiotics throughout a biofilm, microbial cells are often exposed to levels below inhibitory concentrations and may develop resistance. This, as well as the irresponsible use of antibiotics, leads to the selection of pathogens that are difficult to eradicate. The Centers for Disease Control and Prevention use the terms “antibiotic” and “antimicrobial agent” interchangeably. However, a clear distinction between these two terms is required for the purpose of this assessment. Therefore, we define “antibiotics” as pharmaceutically formulated and medically administered substances and “antimicrobials” as a broad category of substances which are not regulated as drugs. This comprehensive minireview evaluates the effect of natural antimicrobials on pathogens in biofilms when used instead of, or in combination with, commonly prescribed anti...
Journal of Microbiology & Experimentation, 2018
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Rhamnolipids, naturally existent biosurfactantsassembledbyrhamnose sugar molecules and βhydroxyalkanoicacids that has wide range of promising profitable applications. In the study Pseudomonas aeruginosabacterial isolates was identified and screened for rhamnolipid production. P. aeruginosa achieved the production of rhamnolipid at room temperature in static cultures of a mineral salts medium containing olive oil. The pure culture was enhanced and optimized at pH-7, temperature-37 o C and olive oil as effective carbon source. The cultural media was optimized using response surface methodology -Box-Behnken with 30 ml of olive oil, 5 g/l NaNO 3 , 4 g/l KH 2 PO 4 and 7.5 g/l FeSO 4 mixture contributes maximum production of rhamnolipid. The R 2 value was 99.8 that correlated with adjusted R 2 value of 99.7 and predicted R 2 value of 99.5 shows the model is significant.
Bacterial-Biofilm-Dispersal-and-Inhibition-Strategies.pdf
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Editorial: Novel approaches in the prevention of bacterial biofilm formation
Frontiers in Cellular and Infection Microbiology
Editorial on the Research Topic Novel approaches in the prevention of bacterial biofilm formation This editorial provides an outline of the papers published in the Frontiers Research Topic "Novel approaches in the prevention of bacterial biofilm formation" in the journal Frontiers in Cellular and Infection Microbiology. Biofilms are cultures of bacteria that have organized themselves inside a polymer matrix made up generally of polysaccharides, proteins, and extracellular DNA that the bacteria manufacture entirely or partially (Vestby et al., 2020).Nature has endowed bacteria with the capacity to build biofilms, which severely threaten humankind. Bacterial biofilms are impervious to the body's innate and adaptive inflammatory defense mechanisms, including antibiotics and disinfection chemicals, as well as phagocytosis. Preventing the development of bacterial biofilms is a promising strategy for lowering the prevalence of pathogenic microorganisms, and emerging techniques for accomplishing this goal require immediate attention (Hall-Stoodley et al., 2004).Through both fundamental and practical research, the Research Topic offers a view on the novel approaches in the prevention of bacterial biofilm formation. In addition, the articles examine a multi-faceted approach to preventing bacterial biofilms using a new chemical substance and exploring new formulation technologies (Iolanda and Gianfranco, 2010; Chen et al., 2013).The goal is to create a commercial solution for patients who require it. This editorial comprises seven publications that focus on the current research related to the prevention of the formation of bacterial biofilms along with a critical review of it. In a study titled "Silicone Foley catheters impregnated with microbial indole derivatives inhibit crystalline biofilm formation by Proteus mirabilis", Amer et al. sought the use of microbial indole extract in catheters can effectively decrease the formation of crystalline biofilm caused by P. mirabilis. Acting on virulence factors at sub-MIC levels without stressing bacterial growth lowers resistance development. This chemical is also safe for human cell lines. This indole extract reduces crystalline biofilm formation by inhibiting virulence factors that affect bacterial motility, adherence, and urease production. Long-term catheterization in animal models and synergistic action with additional anti-virulence drugs are planned to test this technique. The following publication, titled "Effects of TYPE
Identification of natural compounds which inhibit biofilm
Klebsiella pneumoniae, an important opportunistic pathogen, exists as a biofilm in persistent infections and in-dwelling medical devices. With the objective of identifying natural compounds inhibiting biofilm formation in K. pneumoniae, 35clinical isolates were screened,out of which 7 strong biofilm producers were identified. Six natural compounds were tested for their inhibitory effects on bacterial growth and biofilm formation by determining the minimum inhibitory concentration and minimum concentration for biofilm inhibition (MBIC) for each compound. The results show that reserpine followed by linoleic acid, were the most potent biofilm inhibitors. Reserpine, an efflux pump inhibitor was effective at biofilm inhibition at a concentration of 0.0156 mg/mL, 64-fold lower concentration than its MIC. Linoleic acid, an essential fatty acid was effective as a biofilm inhibitor at 0.0312 mg/mL, which is 32-fold lower than its MIC. Berberine, another plant derived antimicrobial, chitosan and eugenol had an MBIC value of 0.0635 mg/mL. Curcumin, a natural phenolic compound was effective at biofilm inhibition at a concentration of 0.25 mg/mL, which is 50 fold less than its MIC. Notably, the MIC and MBIC data on these 6 natural compounds was reproducible in all seven high biofilm forming isolates of K. pneumoniae. The present report is a comprehensive comparative analysis of the dose dependent inhibition of various natural compounds on biofilm formation in K. pneumoniae.
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