Bacteria transfer

In a Centers for Disease Control and Prevention (CDC) study spanning the years 1980-1990, 62% of all nosocomial infections were attributed to bacterial pathogens [3]. An undefined number are due to bacteria transferred by and from the hands and skin. Products such as preoperative skin preparations and surgical scrubs have been used in hospital settings for the reduction of nosocomial infections. Products designed for these uses rapidly and dramatically reduce the levels of resident bacteria on the hands or skin immediately prior to invasive surgical procedures. By definition, they should exhibit a persistent effect. Persistence is prolonged or extended antimicrobial activity which acts to prevent or inhibit the... 

Table 7 Effect of Handwashing on Bacteria Transferred by Handling Ground Beef Glove Juice Extraction...

Table 9 Bacteria Transferred from Chicken to Sterile Ground Beef by Hands Before Washing... 

As shown in Table 9, bacteria were consistently transferred from the chicken to sterile ground beef by unwashed hands. These bacteria were natural contaminants of the chicken. The number of bacteria transferred to the beef was reduced (but not eliminated) by washing with a food service-approved hand sani-... 

Subject number Bacteria transferred after washing with food service approved hand sanitizer/cleanser (logic) Subject number Bacteria transferred after washing with plain soap and water (logio)... 

Table 12 Residual Effect of Two Antimicrobial Products on Bacteria Transferred to Fingers from a Sponge...

Most of the terminal electron acceptors used by bacteria for respiration, such as oxygen, nitrate, and sulfate, are soluble. This means they can make then-way to the cell to receive electrons from the membrane-bound molecules of the respiratory chain. The real question is how bacteria transfer electrons to solids like hematite (a FejOj) and goethite (a-FeOOH) (Figure 3). Because these minerals are effectively insoluble under environmentally relevant conditions, simple dissolution and diffusion of ferric iron to the cell cannot be the answer (ferric iron is the constituent of the mineral that receives electrons). Therefore, bacteria must have other strategies for transferring electrons to minerals during respiration. The question is, what are they ... 

Another mechanism, possibly the dominant one, is that bacteria transfer electrons directly from the cell surface to the mineral after a regulated search and attachment process. A variety of biomolecules (including cytochromes, qui-nones, and dehydrogenases) have been identified as part of this electron-transfer pathway (Schroder et al., 2003). Several of these biomolecules are located on the outer membrane of the cell and presumably make contact with the mineral directly (Lower et al., 2001). Given that the initial rate and long-team extent of electron transfer is correlated with their surface area and the concentration of reactive sites, this seems like a reasonable explanation (Zachara et al., 1998). 

EET mechanisms are nearly as diverse as the bacteria that perform them. Some bacteria transfer electrons to electrodes efficiently on their own while others need help in the form of exogenous redox molecules. Some of the most proficient exoelectrogens likely employ some combination of the mechanisms discussed here (Fig. 9.2). Understanding these mechanisms and how they interplay is integral to future engineering efforts of MFCs along with other bioelectrochemical systems. 

Breton J, Martin J-L, Fleming G R and Lambry J-C 1988 Low-temperature femtosecond spectroscopy of the initial step of electron transfer in reaction centers from photosynthetic purple bacteria Biochemistry 27 8276... 

Pullerits T, Visscher K J, Hess S, Sundstrom V, Freiberg A, Timpmann K and Van Grondelle R 1994 Energy-transfer in the inhomogeneously broadened core antenna of purple bacteria-a simultaneous fit of low-intensity picosecond absorption and fluorescence kinetics Biophys. J. 66 236-48... 

Pullerits T, Chachisvilis M, Fedchenia I and Sundstrom V 1994 Coherent versus incoherent energy transfer in the lightharvesting complexes of photosynthetic bacteria Lietuvos Fizikos Zurnalas 34 329-38... 

Basic Components. The principal components in emulsion polymerization are deionized water, monomer, initiator, emulsifier, buffer, and chain-transfer agent. A typical formula consists of 20—60% monomer, 2—10 wt % emulsifier on monomer, 0.1—1.0 wt % initiator on monomer, 0.1—1.0 wt % chain-transfer agent on monomer, various small amounts of buffers and bacteria control agents, and the balance deionized water. 

Molybdenum. Molybdenum is a component of the metaHoen2ymes xanthine oxidase, aldehyde oxidase, and sulfite oxidase in mammals (130). Two other molybdenum metaHoen2ymes present in nitrifying bacteria have been characteri2ed nitrogenase and nitrate reductase (131). The molybdenum in the oxidases, is involved in redox reactions. The heme iron in sulfite oxidase also is involved in electron transfer (132). 

Bacteria produce chromosomady and R-plasmid (resistance factor) mediated P-lactamases. The plasmid-mediated enzymes can cross interspecific and intergeneric boundaries. This transfer of resistance via plasmid transfer between strains and even species has enhanced the problems of P-lactam antibiotic resistance. Many species previously controded by P-lactam antibiotics are now resistant. The chromosomal P-lactamases are species specific, but can be broadly classified by substrate profile, sensitivity to inhibitors, analytical isoelectric focusing, immunological studies, and molecular weight deterrnination. Individual enzymes may inactivate primarily penicillins, cephalosporins, or both, and the substrate specificity predeterrnines the antibiotic resistance of the producing strain. Some P-lactamases are produced only in the presence of the P-lactam antibiotic (inducible) and others are produced continuously (constitutive). 

Some polymyxins are sold for second-line systemic therapy. Polymyxin B sulfate and colistimethate sodium can be used for intravenous, intramuscular, or intrathecal administration, especially for Pseudomonas aerupinosa mP QXiosis, but also for most other gram-negative organisms, such as those resistant to first-line antibiotics. Nephrotoxicity and various neurotoxicities are common in parenteral, but not in topical, use. Resistance to polymyxins develops slowly, involves mutation and, at least in some bacteria, adaptation, a poorly understood type of resistance that is rapidly lost on transfer to a medium free of polymyxin. Resistance can involve changes in the proteins, the lipopolysaccharides, and lipids of the outer membrane of the cell (52). Polymyxin and colistin show complete cross-resistance. 

Packaging. The beer in pressure tanks is transferred to bottling, canning, and racking, or in some cases, to road tankers. During this filling operation it is important that the beer does not come into contact with oxygen, does not lose carbon dioxide, and is not contaminated by molds, yeasts, or bacteria. 

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