A bactericide or bacteriocide, sometimes abbreviated Bcidal, is a substance which kills bacteria. Bactericides are disinfectants, antiseptics, or antibiotics. However, material surfaces can also have bactericidal properties based solely on their physical surface structure, as for example biomaterials like insect wings.
Definition
A bactericide is a substance which kills bacteria. Bactericides are chemical substances like disinfectants, antiseptics, or antibiotics.
cationic surfactants, such as 0.05 – 0.5% benzalkonium, 0.5 – 4% chlorhexidine, 0.1 – 2% octenidine solutions.
Others are generally not applicable as safe antiseptics, either because of their corrosive or toxic nature.
Antibiotics
Bactericidal antibiotics kill bacteria; bacteriostatic antibiotics slow their growth or reproduction. Bactericidal antibiotics that inhibitcell wall synthesis: the beta-lactam antibiotics, cephalosporins and vancomycin. Also bactericidal are daptomycin, fluoroquinolones, metronidazole, nitrofurantoin, co-trimoxazole, telithromycin. Aminoglycosidic antibiotics are usually considered bactericidal, although they may be bacteriostatic with some organisms. As of 2004, the distinction between bactericidal and bacteriostatic agents appeared to be clear according to the basic/clinical definition, but this only applies under strict laboratory conditions and it is important to distinguish microbiological and clinical definitions. The distinction is more arbitrary when agents are categorized in clinical situations. The supposed superiority of bactericidal agents over bacteriostatic agents is of little relevance when treating the vast majority of infections with gram-positive bacteria, particularly in patients with uncomplicated infections and noncompromised immune systems. Bacteriostatic agents have been effectively used for treatment that are considered to require bactericidal activity. Furthermore, some broad classes of antibacterial agents considered bacteriostatic can exhibit bactericidal activity against some bacteria on the basis of in vitro determination of MBC/MIC values. At high concentrations, bacteriostatic agents are often bactericidal against some susceptible organisms. The ultimate guide to treatment of any infection must be clinical outcome.
Surfaces
Material surfaces can exhibit bactericidal properties because of their crystallographic surface structure. In the mid 2000s it was shown that metallic nanoparticles can kill bacteria. The effect of a silver nanoparticle for example depends on its size with a preferential diameter of about 1-10 nm to interact with bacteria. In 2013, cicada wings were found to have a selective anti-Gram-negative bactericidal effect based on their physical surface structure. Mechanical deformation of the more or less rigid nanopillars found on the wing releases energy, striking and killing bacteria within minutes, hence called a mechano-bactericidal effect.
