Bactericidal Effects

In Cosmetics. Amino acids and their derivatives occur in skin protein, and they exhibit a controlling or buffering effect of pH variation in skin and a bactericidal effect (216). Serine is one component of skin care cream or lotion. Ai-Acylglutamic acid triethanolamine monosalt is used for shampoo. Glucose glutamate is a moisturizing compound for hair and skin (234). 

For optimum disinfection in swimming pools, the pH is maintained in the 7.2 to 7.6 range where HOCl represents 69—47% of the FAC. By contrast, the HOBr fraction varies from 97 to 93%. Nevertheless, the bactericidal effectiveness of HOCl is greater than that of HOBr below pH 8 on a molar basis (8). However, above pH 8 the superiority of HOCl is overcome by the fact that the concentration of C10 exceeds that of HOCl above pH 7.5, whereas the concentration of HOBr stiU exceeds that of BrO up to pH 8.7. Hypochlorous acid is a better viricide than HOBr, but HOBr is more effective against certain algae (9). 

Specific biological activity of carboxylic acids peroxide derivatives in compaiison with their oxidation ability and ionization degree in aqueous solutions has been considered. Peroxyoctanoic, diperoxynonandioic and diperoxydecandioic acids give the most intense bactericidal effect among researched cai boxylic acids peroxide derivatives. The perspectives of use of the aliphatic middle-chain peracid C8-C9 as anti-infective agents have been discussed. 

Bactericides are substances that destroy bacteria, and they can be used in various ways. They may be incorporated into the soluble-oil concentrate, either at concentrations suitable to protect the oil in storage, or at levels sufficient to provide a persistent bactericidal effect on the emulsion in service. The cost of providing sufficient bactericide to cover the use of the soluble oil at a high dilution might prove prohibitive. Continued use of the same bactericide may produce resistant strains of bacteria. 

The aminoglycosides exert their bactericidal effect by blocking a step in protein synthesis necessary for bacterial multiplication. They disrupt the functional... 

The bactericidal effects of ionizing radiation have been known for a century, and for over 80 years it has been known that ionizing radiation kills the Ttichinella spiralis parasite, which infects raw pork. By the mid-1970s, international experts had concluded that irradiating foods preserves them without creating any toxicological hazards. Only in the last decade, however, has preservation by irradiation been applied commercially. 

Tests considered to date have, without exception, measured unequivocally the bactericidal effect. In some instances it is useful to know the minimum concentration which inhibits growth (reproduction) rather than those concentrations which achieve a rapid kill. The implications ofthe terms bactericide and bacteriostat were discussed earlier (see section 1.1, Fig. 11.1). 

Possibly the most significant discovery in the metabolism of aromatic azo compounds had implications that heralded the age of modem chemotherapy. It was shown that the bactericidal effect of the azo dye Prontosil in vivo was in fact due to the action of its transformation product, sulfanilamide, which is an antagonist of 4-aminobenzoate that is required for the synthesis of the vitamin folic acid. Indeed, this reduction is the typical reaction involved in the first stage of the biodegradation of aromatic azo compounds. 

Fisher (1977) found that the bactericidal effects varied from brand to brand and Fisher McCabe (1978) related this to chemical composition. Only cements which give rise to high alkalinity (pH = 11) are effective. These are the cements which are readily decomposed by water, and this relates to the plasticizer used. Hydrophilic plasticizers are required if these cements are to be clinically effective. 

Concerning the mechanism of action of catechins, studies carried out on S. aureus and E. coli cells by Ikigai et al. [72] reported that their bactericidal effect is primarily involved in the damage of bacterial membranes catechins induce a rapid leakage of small molecules entrapped in the intraliposomal space, determining the aggregation of the liposomes. These actions cause damage in the membrane lipid bilayer and cell death (Table 1). 

Other quaternary ammonium germicides, ben-zethonium chloride and benzalkonium bromide, have been used in several ophthalmic solutions. While these have the advantage of not being a chemical mixture, they do not possess the bactericidal effectiveness of benzalkonium chloride and are subject to the same incompatibility limitations. In addition, the maximum concentration for benzethonium chloride is 0.01%. Several new products that form gels in the eye, like Timolol Gel Forming Solution and Timoptic-XE, employ another quaternary preservative, BDAB, in the formulation. 

Pure Ti02 was recently reported to be active in the disinfection of water contaminated by spores of the type Fusarium solani [142], Bacillus anthracis [143], or Cryptosporidium parvum oocysts [144], or when supported as nanocomposites on zeolite H(i for E. coli deactivation [145], and it found applications in water treatment as a replacement for chlorine. Ag-Ti02 immobilized systems were used for inactivation of bacteria, coupling the visible light response of the system and the strong bactericidal effect of Ag [146]. Silver was deposited on hydroxyapatite to form nanocomposites with a high capacity for bacterial adsorption and inactivation [147], or used for airborne bacterial remediation in indoor air [148],... 

Chen, F., Yang, X., Xu, F., Wu, Q., and Zhang, Y. (2009) Correlation of photocatalytic bactericidal effect and organic matter degradation ofTi02. Parti observation of phenomena. Environmental Science and Technology,... 

The bactericidal effect of hypochlorite is due to the presence of available chlorine. This is hypochlorous acid (HOC1) and hypochlorite ions (OCl ), where HOC1 is the most effective disinfectant (Betts and Everis, 2005). The dissociation of HOC1 is dependent on pH and at 20 °C and between pH 6.0 and 8.0 the percentages of HOC1 is approximately 97% and 23%, respectively (Beuchat, 1998). This suggests that the pH should be as low as possible, but... 

Different organic acids, primarily lactic acid, have been successfully used for decontamination of whole livestock carcasses, and the application of different organic acids used for decontamination has also been tested in the fruit and vegetable industry. Organic acids other than lactic acid that are known to have bactericidal effects are acetic, benzoic, citric, malic, propanoic, sorbic, succinic and tartaric acids (Betts and Everis 2005). The antimicrobial action is due to a reduction in the pH in the bacterial environment, disruption of membrane transport, anion accumulation or a reduction in the internal pH in the cell (Busta et al., 2001). Many fruits contain naturally occurring organic acids. Nevertheless, some strains, for example E. coli 0157, are adapted to an acidic environment. Its survival, in combination with its low infective dose, makes it a health hazard for humans. 

The effectiveness of bacteriocins is often a function of environmental factors such as pH, temperature, food composition, structure, and food microflora (De Vuyst and Leroy 2007). A novel bacteriocin-like substance produced by Bacillus licheniformis P40 inhibits the activity of the soft rot bacterium Envinia carotovora. This compound caused a bactericidal effect on the pathogen cells at a 30 p.g/mL concentration (Cladera-Olivera and others 2006). 

Somewhat different results were obtained by Zuckerman79 on the comparative bactericidal effects of group IVa di- and triorganoderivatives. 

In bacteria (Escherichia coli), paraquat is concentrated, reduced to the monocation radical, and combines with molecular oxygen to produce the superoxide radical within the cell. Copper and iron are essential mediators in bactericidal effects. The cytoplasmic membrane is the target organelle in paraquat toxicity to E. coli, and extent of damage correlates positively with levels of these metals (Kohen and Chevion 1988). 

Integration of both pharmacokinetic and pharmacodynamic properties of an agent is important when choosing antimicrobial therapy to ensure efficacy and prevent resistance. Antibiotics may demonstrate concentration-dependent (aminoglycosides and fluoroquinolones) or time-depen-dent (/l-1 acta ms) bactericidal effects. 

The most important pharmacodynamic relationship for antimicrobials that display time-depen dent bactericidal effects is the duration that drug concentrations exceed the MIC. 

The combination of penicillin G or ampicillin with an aminoglycoside results in a bactericidal effect. Patients should be treated for 2 to 3 weeks after defervescence to prevent the possibility of relapse. Combination therapy is given for at least 10 days with the remainder completed with penicillin G or ampicillin alone. 

Many plasmids are known to possess three properties (1) increased resistance to the bactericidal effects of UV and chemical mutagens, (2) increased spontaneous mutagenesis, and (3) increased susceptibility to UV and chemically induced mutagenesis. Some plasmids possess all three properties others may possess just one, for example, increased susceptibility to mutagenesis (review Mortelmans and Dousman, 1986). Often the profile of activity depends on the DNA repair status of the host cell (Pinney, 1980). Plasmid pKMIOl carries DNA repair genes and has been widely used in strains used in bacterial mutagenicity tests. 

Odell, E. W., Segal, A. W. (1988). The bactericidal effects of the respiratory burst and the myeloperoxidase system isolated in neutrophil cytoplasts. Biochim. Biophys. Acta 971, 266-74. 

The formation of antibodies is only one mechanism by which an animal may protect itself from substances or microorganisms that are potentially harmful. A mechanical protection against infection is provided by the presence of an intact skin surface and membranes together with the secretion of mucus from many internal membrane surfaces. The acids secreted by the stomach and skin have a bactericidal effect as does the presence in many body fluids of certain enzymes, particularly lysozyme. 

Arnold RR, Cole MF, McGhee JR (1977) A bactericidal effect for human lactoferrin. Science 197(4300) 263-265. 

An in vitro investigation into the bactericidal effects of a dental ultrasonic descaler on bacterial biofilms using Actinobacillus actinomycctcmcomitans and Porphyromonas gin-givalis has been reported [49]. Suspensions of the bacteria were subjected to the vibrations of a Cavitron PI insert for 2.5 and 5.0 min in an acoustically-simulated model substrate. A 60 % kill rate was achieved at a temperature of around 50 °C which constituted an alternative treatment for bacterial biofilms. This study suggested that a similar approach could be used in the clean-up of a range of biofQms considered to be the cause of a range of environmental hazards. 

Other glycoflavonoids (rutin, nicotiflorin, hyperoside and iso-quercitrin) were purified and identified from Tripodanthus acutifolius (Ruiz and Pavon) Van Tieghem (Loranthaceae) leaves." These compounds showed bactericidal effect at a concentration of 4 mg/mL... 

The effect of antibacterial drugs can be observed in vitro (3). Bacteria multiply in a growth medium under control conditions. If the medium contains an antibacterial drug, two results can be discerned 1. bacteria are killed—bactericidal effect 2. bacteria survive, but do not multiply-bacteriostatic effect Although variations may occur under therapeutic conditions, different drugs Lullmann, Color Atlas of Pharmacology... 

Co-trimoxazole is a combination of trimethoprim and the sulfonamide sulfamethoxazole. Since THF synthesis is inhibited at two successive steps, the antibacterial effect of co-trimoxazole is better than that of the individual components. Resistant pathogens are infrequent a bactericidal effect may occur. Adverse effects correspond to those of the components. 

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