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Nanomaterials Application in Biological Sensing of Biothreat Agents
Published in Jayeeta Chattopadhyay, Nimmy Srivastava, Application of Nanomaterials in Chemical Sensors and Biosensors, 2021
Jayeeta Chattopadhyay, Nimmy Srivastava
Bioagents or biological agents are pathogens microorganism or their toxic products which are a menace for human health (LeClaire and Pitt 2005, Dembek 2007, Sapsford et al. 2008, Dembek 2011). They include both naturally occurring and man-made bioengineered pathogens that induce health risk from their natural outbreak or premeditated release. These agents are deliberately used in biowarfare or bioterrorism due to an array of peculiar features like: ➢ Infection efficiency signifies how easily it can establish itself with the host.➢ Virulence signifies the severity of the disease caused by the microorganism.➢ The contagious nature of a pathogen signifies how deliberately it can get disseminated from one person to another causing the infection (Dembek 2007, Dembek 2011).
Epizootiology of Fish Diseases
Published in John A Plumb, Health Maintenance Of Cultured Fishes, 1994
Virulence is a measure of a pathogenic organism’s ability to cause disease. The disease-causing ability of a pathogen may range from low to high, and all levels between the two extremes. Some organisms, especially facultative bacteria, can vary greatly in virulence from location to location. A. hydrophila, a facultative bacterium in water, may be highly virulent in one area, while an isolate from another body of water may be avirulent (i.e., not pathogenic). Also, when A. hydrophila is isolated from diseased fish, it is usually more virulent than when isolated from water.5 When highly virulent strains of pathogens are present, it is more likely that a severe disease outbreak will occur than when a low virulence organism is present. Although it is difficult to manipulate the virulence of pathogenic organisms, management can help prevent severe disease outbreaks by ensuring that environmental conditions are more favorable to the host than to the pathogen.
Quorum Sensing
Published in Vineet Kumar, Vinod Kumar Garg, Sunil Kumar, Jayanta Kumar Biswas, Omics for Environmental Engineering and Microbiology Systems, 2023
Archisman Bhunia, Kumar Narayan, Abhilasha Singh, Asmeeta Sircar, Nivedita Chatterjee
Virulence is in general defined as the degree of toxicity or the injury-inducing capacity of a microorganism. Virulence and pathogenicity are often used interchangeably. The virulence of bacteria describes their capability of producing an exotoxin and/or endotoxin (Zipfel et al., 2006). Staphylococcus aureus is known to uses the Agr quorum sensing circuit to induce inflammation as an effort to enhance the degree of nutritional uptake, causing a manifestation of food poisoning. Fengycin, a cyclic lipopeptide produced from Bacillus sp., possesses an amphipathic structure and is known to exhibit antifungal properties. This chemical often helps to disrupt the virulence caused by S. aureus by striving for S. aureus autoinducer-binding sites, alleviating bacterial consortium formation and thereby poisoning. The autoinducing peptide, also known as AIP, is a precursor manufactured from a compound named agrD. AgrB, another AIP transporter, synthesizes the precursor to the developed or fully matured AIP and systematically transports it outside the cell membrane. AIPs can be recognized by a two-component signal transduction pathway, which involves a membrane-bound histidine kinase AgrC and a response regulator AgrA. On phosphorylation, the stimuli from AgrA activate the P2 and P3 promoters, which encode the agr operon (called RNAII) and the RNAIII regulatory RNA, respectively. The RNAIII post-transcriptionally triggers the virulence factor synthesis and subdues the expression of repressor of toxins (Rot), thus leading to further activation of virulence factors along the cascade (Rutherford and Bassler, 2012).
Multidrug resistant Escherichia coli from fresh produce sold by street vendors in South African informal settlements
Published in International Journal of Environmental Health Research, 2021
Tintswalo Baloyi, Stacey Duvenage, Erika Du Plessis, Germán Villamizar-Rodríguez, Lise Korsten
The surveillance of antimicrobial resistant bacteria and their genetic determinants has become more common within food research (Ben Said et al. 2016). Escherichia coli has increasingly been reported as a reservoir of antimicrobial resistance genes, many of which were acquired through horizontal gene transfer (Poirel et al. 2018). Both pathogenic and commensal E. coli can be a reservoir of antibiotic resistance genes (Du Plessis et al. 2017; Poirel et al. 2018). The presence of virulence and resistance genes increases the pathogenicity of microorganism and therefore the severity of the infection (El-Baky et al. 2020). Escherichia coli, both pathogenic and generic, and multidrug resistant (MDR) microorganisms can be present on fresh produce (Jongman and Korsten 2016; Du Plessis et al. 2017; Kilonzo-Nthenge et al. 2018) and readily acquired through food and water (Collignon 2009). Emergence of multidrug resistant E. coli can be considered a public health concern (Sa´enz et al. 2004). Often, the presence of foodborne pathogens and multidrug resistant bacteria on fresh produce is due to contamination during production – postharvest practices (Lynch et al. 2006) or, at the point of sale. Given the scale of consumption of fresh produce, it is imperative to establish a baseline of E. coli occurrence and prevalence in the informal sector. In order to determine the ecological niche, disease causing ability and tracking of E. coli Clermont et al. (2013) developed a phylogenetic typing method which groups E. coli into eight phylogenetic groups (A, B1, B2, C, D, E, F and E. coli cryptic clade I). Group A strains include mainly commensal E. coli, whilst most virulent extraintestinal strains belong to group B2 and D (Johnson and Stell 2002). Additionally, group B1 is dominated by plant associated E. coli and groups A and B2 contain many animal associated strains. Group C is closely related to Group B1 (Escobar-Páramo et al. 2004). Group E has been found to be associated with human and animal sources, for example, E. coli O157:H7 is grouped in this phylogenetic group (Clermont et al. 2011).