Bactericidal mechanism

A number of antibiotics produced by fungi of the genus Cephalosporium have been identified. These antibiotics called cephalosporins contain, in common with the penicillins, a p-lactam ring. In addition to the numerous penicillins and cephalosporins in use, three other classes of p-lactam antibiotics are available for clinical use. These are the carbapenems, the carbacephems, and the monobactams. All 3-lactam antibiotics have the same bactericidal mechanism of action. They block a critical step in bacterial cell wall synthesis. 

In the face of so much evidence that the immune response in gonococcal infection is irrelevant, nonprotective, or even deleterious are observations that indicate that the host response does participate in the resolution of infection. In vitro, antibody- and complement-mediated lysis is an effective bactericidal mechanism (R4, S9). DGI, unlike local infections, does appear to protect against dissemination on subsequent exposure (R14), and patients with deficiencies of terminal complement components are particularly prone to disseminated infection (P8). By and large, characteristics of the bacteria, rather than host factors, appear to be more important in allowing gonococci to elude immune destruction and cause local, locally invasive, or dissemi-... 

The antibacterial efficacy of Ppy deposited on cotton fabrics was quantitatively evaluated under dynamic contact conditions according to the American Society for Testing and Materials (ASTM), ASTM E2149-01. Moreover, the bactericidal mechanism of Ppy on Escherichia coli bacteria was preliminarily investigated [55]. 

The various sulphonamides differ in their specificity to various bacteria and in their ease of absorption and excretion. They are bacteriostatic (inhibiting growth) and not bactericidal, acting by allowing the natural body mechanisms to destroy the bacteria. 

The bactericidal and enzymatic action of dyes, particularly of vinyl derivatives of 3,4,5-substituted thiazolium, for example, 45 (Scheme 70) (139), have been systematically studied to know more about the basic mechanisms involved (140). 

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). 

Maness, P.C., Smolinski, S., Blake, D.M., Huang, Z., Wolfrum, E.J., and Jacoby, W.A. (1999) Bactericidal activity of photocatalytic Ti02 reaction toward an understanding of its killing mechanism. Applied and Environment Microbiology,... 

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. 

Mechanisms by which ozone might interfere with bactericidal function include an alteration in cell-membrane function that produces a loss in phagocytic ability and is perhaps mediated by lipid peroxides and a decrease in the ability of veolar macrophages to kill phagocytized bacteria. Leukocytes in general appear to have a multiplicity of mechanisms for destroying ingested bacteria. 

Babior, B. M., Kipnis, R. S., and Cumutte, J. T. (1973) Biological defense mechanisms. The production by leukocytes of superoxide, a potent bactericidal agent. J. Clin. Invest. 52, 741-744. 

Isoniazid is bactericidal against growing M. tuberculosis. Its mechanism of action remains unclear. (In the bacterium it is converted to isonicotinic acid, which is membrane impermeable, hence likely to accumulate intracellu-larly.) Isoniazid is rapidly absorbed after oral administration. In the liver, it is inactivated by acetylation, the rate of which is genetically controlled and shows a characteristic distribution in different ethnic groups (fast vs. slow acetylators). Notable adverse effects are peripheral neuropathy, optic neuritis preventable by administration of vitamin Be (pyridoxine) hepatitis, jaundice. 

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