Pharmaceutical applications of chitosan

Fighting bacterial resistance is one of the concerns in modern days, as antibiotics remain the main resource of bacterial control. Data shows that for every antibiotic developed, there is a microorganism that becomes resistant to it. Natural polymers, as the source of antibacterial agents, offer a new way to fight bacterial infection. The advantage over conventional synthetic antibiotics is that natural antimicrobial agents are biocompatible, non-toxic, and inexpensive. Chitosan is one of the natural polymers that represent a very promising source for the development of antimicrobial agents. In addition, chitosan is biodegradable, non-toxic, and most importantly, promotes wound healing, features that makes it suitable as a starting material for wound dressings. This paper reviews the antimicrobial properties of chitosan and describes the mechanisms of action toward microbial cells as well as the interactions with mammalian cells in terms of wound healing process. Finally, the applications of chitosan as a wound-dressing material are discussed along with the current status of chitosan-based wound dressings existing on the market.

Chitosan as a Wound Dressing Starting Material: Antimicrobial Properties and Mode of Action

Antibacterial activity of chitosan and its derivatives and their interaction mechanism with bacteria: Current state and perspectives

1796 Introduction: The Polymerase Chain Reaction (PCR) has become the cornerstone of molecular diagnosis, with almost every genetic test aiming to identify DNA sequence variation incorporating PCR. A commonly encountered problem is that variant DNA sequences exist in the presence of a large majority of wild type alleles such as when DNA is obtained from heterogeneous cancer biopsies or when fetal alleles are sought in maternal blood. As a result, downstream assays are severely limited in their ability to identify subtle genetic changes that can have profound impact in clinical decision-making and outcome. We describe Co-amplification at Lower Denaturation temperature (COLD-PCR), a novel form of PCR that amplifies minority alleles selectively from mixtures of wild-type and mutation-containing sequences irrespective of the mutation type or position on the sequence (Nature Medicine, In Press).  Methods: In COLD-PCR, an intermediate annealing temperature is used during PCR-cycling to allow cross-hybridization of mutant and wild type alleles; hetero-duplexes, which melt at lower temperatures than homo-duplexes, are then selectively denatured and amplified at Critical Denaturation Temperature (Tc), while homo-duplexes remain double-stranded and do not amplify efficiently. By fixing the denaturation temperature to Tc, mutations at any position along the sequence are enriched during COLD-PCR amplification. To validate COLD-PCR, we used serial dilutions of DNA from tumor-derived cell lines containing point mutations or micro-deletions at different positions along p53 exon 8 and Kras exon 1 (codons 12-13), or samples with micro-deletions in EGFR exon 19. In addition, genomic DNA from a series of colon and lung cancer surgical specimens, and plasma-circulating DNA collected under IRB approval were utilized for validation on clinical specimens.  Results: By replacing regular PCR with COLD-PCR prior to application of a range of assays (Sanger sequencing; Pyrosequencing; MALDI-TOF; dHPLC; RFLP; and Taqman) we improved mutation detection sensitivity up to 100-fold and identified several additional p53/Kras/EGFR mutations in heterogeneous cancer samples. 4 of 43 surgical samples and 3 of 10 plasma samples tested contained clinically important mutations that were not detected by any of the methods tested when preceded by regular-PCR, but they were detectable following COLD-PCR.  Conclusion: Replacement of regular PCR with COLD-PCR provides a universal boost to most mutation detection technologies and enables them to be used with the required confidence in routine screening of cancer specimens for somatic mutations, including low-level mutation screening of surgical/FFPE tumor samples or bodily fluids. COLD-PCR is also anticipated to find application in pre-natal diagnosis, in infectious diseases and in epigenetics.

Replacing PCR with COLD-PCR enriches variant DNA sequences and redefines the sensitivity of genetic testing in cancer

Milk produced in udder cells is sterile but due to its high nutrient content, it can be a good growth substrate for contaminating bacteria. The quality of milk is monitored via somatic cell counts and total bacterial counts, with prescribed regulatory limits to ensure quality and safety. Bacterial contaminants can cause disease, or spoilage of milk and its secondary products. Aerobic spore-forming bacteria, such as those from the genera Sporosarcina, Paenisporosarcina, Brevibacillus, Paenibacillus, Geobacillus and Bacillus, are a particular concern in this regard as they are able to survive industrial pasteurisation and form biofilms within pipes and stainless steel equipment. These single or multiple-species biofilms become a reservoir of spoilage microorganisms and a cycle of contamination can be initiated. Indeed, previous studies have highlighted that these microorganisms are highly prevalent in dead ends, corners, cracks, crevices, gaskets, valves and the joints of stainless steel equipment used in the dairy manufacturing plants. Hence, adequate monitoring and control measures are essential to prevent spoilage and ensure consumer safety. Common controlling approaches include specific cleaning-in-place processes, chemical and biological biocides and other novel methods. In this review, we highlight the problems caused by these microorganisms, and discuss issues relating to their prevalence, monitoring thereof and control with respect to the dairy industry.

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The Prevalence and Control of Bacillus and Related Spore-Forming Bacteria in the Dairy Industry

Application, mode of action, and in vivo activity of chitosan and its micro- and nanoparticles as antimicrobial agents: A review.

Foodborne diseases are an important cause of morbidity and mortality. According to the World Health Organization, there are 31 main global hazards, which caused in 2010 600 million foodborne illnesses and 420000 deaths. Among them, Salmonella spp. is one of the most important human pathogens, accounting for more than 90000 cases in Europe and even more in the United States per year. In the current study we report the development, and thorough evaluation in food samples, of a microfluidic system combining loop-mediated isothermal amplification with gold nanoparticles (AuNPs). This system is intended for low-cost, in situ, detection of different pathogens, as the proposed methodology can be extrapolated to different microorganisms. A very low limit of detection (10 cfu/25 g) was obtained. Furthermore, the evaluation of spiked food samples (chicken, turkey, egg products), completely matched the expected results, as denoted by the index kappa of concordance (value of 1.00). The results obtained for the relative sensitivity, specificity and accuracy were of 100% as well as the positive and negative predictive values.

/pdf/combination-of-microfluidic-loop-mediated-isothermal-1vatj0cl60.pdf

Combination of Microfluidic Loop-Mediated Isothermal Amplification with Gold Nanoparticles for Rapid Detection of Salmonella spp. in Food Samples.

Rapid and sensitive detection of viable Listeria monocytogenes in food products by a filtration-based protocol and qPCR.

Engineering of chitosan-derived nanoparticles to enhance antimicrobial activity against foodborne pathogen Escherichia coli O157:H7.

Microbiological analysis of food is an integrated part of microbial safety management in the food chain. Monitoring and controlling foodborne pathogens are traditionally carried out by conventional microbiological methods based on culture-dependent approaches in control laboratories and private companies. However, polymerase chain reaction (PCR) has revolutionized microbiological analysis allowing detection of pathogenic microorganisms in food, without the necessity of classical isolation and identification. However, at present, PCR and quantitative polymerase chain reaction (qPCR) are essential analytical tools for researchers working in the field of foodborne pathogens. This manuscript reviews recently described qPCR methods applied for foodborne bacteria detection, serving as economical, safe, and reliable alternatives for application in the food industry and control laboratories. Multiplex qPCR, which allows the simultaneous detection of more than one pathogen in one single reaction, saving co...

https://www.tandfonline.com/doi/pdf/10.1080/23311932.2015.1013771

Alejandro Garrido-Maestu

Papers

Application, mode of action, and in vivo activity of chitosan and its micro- and nanoparticles as antimicrobial agents: A review.

Combination of Microfluidic Loop-Mediated Isothermal Amplification with Gold Nanoparticles for Rapid Detection of Salmonella spp. in Food Samples.

Rapid and sensitive detection of viable Listeria monocytogenes in food products by a filtration-based protocol and qPCR.

Engineering of chitosan-derived nanoparticles to enhance antimicrobial activity against foodborne pathogen Escherichia coli O157:H7.

Detection of foodborne pathogens by qPCR: A practical approach for food industry applications