A bactericide or bacteriocide, sometimes abbreviated Bcidal, is a substance which kills
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
. 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.
Disinfectants
The most used
disinfectants are those applying
*active
chlorine
Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
(i.e.,
hypochlorites,
chloramine
Chloramines refer to derivatives of ammonia and organic amines wherein one or more N-H bonds have been replaced by N-Cl bonds. Two classes of compounds are considered: inorganic chloramines and organic chloramines.
Inorganic chloramines
Inorgan ...
s,
dichloroisocyanurate and
trichloroisocyanurate
Trichloroisocyanuric acid is an organic compound with the formula (C3Cl3N3O3). It is used as an industrial disinfectant, bleaching agent and a reagent in organic synthesis. This white crystalline powder, which has a strong "chlorine odour," is ...
, wet chlorine,
chlorine dioxide, etc.),
*active
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
(
peroxide
In chemistry, peroxides are a group of compounds with the structure , where R = any element. The group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable.
The most common peroxide is hydrogen p ...
s, such as
peracetic acid
Peracetic acid (also known as peroxyacetic acid, or PAA) is an organic compound with the formula CH3CO3H. This peroxy acid is a colorless liquid with a characteristic acrid odor reminiscent of acetic acid. It can be highly corrosive.
Peracetic ...
,
potassium persulfate,
sodium perborate,
sodium percarbonate, and
urea perhydrate),
*
iodine (
povidone-iodine,
Lugol's solution, iodine tincture, iodinated nonionic surfactants),
*concentrated
alcohols (mainly
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
,
1-propanol, called also
n-propanol
Propan-1-ol (also propanol, n-propyl alcohol) is a primary alcohol with the formula and sometimes represented as PrOH or ''n''-PrOH. It is a colorless liquid and an isomer of 2-propanol. It is formed naturally in small amounts during many ferm ...
and
2-propanol
Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a colorless, flammable organic compound with a pungent alcoholic odor. As an isopropyl group linked to a hydroxyl group ( chemical formula ) it is the s ...
, called
isopropanol
Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a colorless, flammable organic compound with a pungent alcoholic odor. As an isopropyl group linked to a hydroxyl group (chemical formula ) it is the sim ...
and mixtures thereof; further,
2-phenoxyethanol
Phenoxyethanol is the organic compound with the formula C6H5OC2H4OH. It is a colorless oily liquid. It can be classified as a glycol ether and a phenol ether. It is a common preservative in vaccine formulations.
Use
Phenoxyethanol has germi ...
and 1- and
2-phenoxypropanols are used),
*
phenolic substances (such as
phenol
Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it r ...
(also called "carbolic acid"),
cresol
Cresols (also hydroxytoluene or cresylic acid) are a group of aromatic organic compounds. They are widely-occurring phenols (sometimes called ''phenolics'') which may be either natural or manufactured. They are also categorized as methylphenol ...
s such as
thymol
Thymol (also known as 2-isopropyl-5-methylphenol, IPMP), , is a natural monoterpenoid phenol derivative of ''p''-Cymene, isomeric with carvacrol, found in oil of thyme, and extracted from '' Thymus vulgaris'' (common thyme), ajwain, and va ...
, halogenated (chlorinated, brominated) phenols, such as
hexachlorophene,
triclosan
Triclosan (sometimes abbreviated as TCS) is an antibacterial and antifungal agent present in some consumer products, including toothpaste, soaps, detergents, toys, and surgical cleaning treatments. It is similar in its uses and mechanism of act ...
,
trichlorophenol,
tribromophenol,
pentachlorophenol, salts and isomers thereof),
*
cationic surfactants
Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming ...
, such as some
quaternary ammonium cations (such as
benzalkonium chloride,
cetyl trimethylammonium bromide or chloride,
didecyldimethylammonium chloride,
cetylpyridinium chloride,
benzethonium chloride) and others, non-quaternary compounds, such as
chlorhexidine,
glucoprotamine,
octenidine
Octenidine dihydrochloride is a cationic surfactant, with a gemini-surfactant structure, derived from pyridine. It is active against Gram-positive and Gram-negative bacteria. Since 1987, it has been used primarily in Europe as an antiseptic pri ...
dihydrochloride etc.),
*strong
oxidizer
An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...
s, such as
ozone
Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the l ...
and
permanganate
A permanganate () is a chemical compound containing the manganate(VII) ion, , the conjugate base of permanganic acid. Because the manganese atom is in the +7 oxidation state, the permanganate(VII) ion is a strong oxidizing agent. The ion is a ...
solutions;
*
heavy metals and their salts, such as colloidal
silver
Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...
,
silver nitrate
Silver nitrate is an inorganic compound with chemical formula . It is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides. It was once called ''lunar causti ...
,
mercury chloride Mercury chloride can refer to:
*Mercury(II) chloride or mercuric chloride (HgCl2)
*Mercury(I) chloride
Mercury(I) chloride is the chemical compound with the formula Hg2Cl2. Also known as the mineral calomel (a rare mineral) or mercurous chloride, ...
,
phenylmercury salts,
copper sulfate Copper sulfate may refer to:
* Copper(II) sulfate, CuSO4, a common compound used as a fungicide and herbicide
* Copper(I) sulfate
Copper(I) sulfate, also known as cuprous sulfate, is an inorganic compound with the chemical formula Cu2 SO4. It ...
,
copper oxide-chloride etc. Heavy metals and their salts are the most toxic and environment-hazardous bactericides and therefore their use is strongly discouraged or prohibited
* strong
acids (phosphoric, nitric, sulfuric, amidosulfuric, toluenesulfonic acids), pH < 1, and
*
alkalis (sodium, potassium, calcium hydroxides), such as of pH > 13, particularly under elevated temperature (above 60 °C), kills bacteria.
Antiseptics
As
antiseptics (i.e., germicide agents that can be used on human or animal body, skin, mucoses, wounds and the like), few of the above-mentioned disinfectants can be used, under proper conditions (mainly concentration, pH, temperature and toxicity toward humans and animals). Among them, some important are
*properly diluted
chlorine
Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...
preparations (f.e.
Dakin's solution, 0.5% sodium or potassium hypochlorite solution, pH-adjusted to pH 7 – 8, or 0.5 – 1% solution of sodium benzenesulfochloramide (
chloramine
Chloramines refer to derivatives of ammonia and organic amines wherein one or more N-H bonds have been replaced by N-Cl bonds. Two classes of compounds are considered: inorganic chloramines and organic chloramines.
Inorganic chloramines
Inorgan ...
B)), some
*
iodine preparations, such as
iodopovidone in various
galenics (ointment, solutions, wound plasters), in the past also
Lugol's solution,
*
peroxide
In chemistry, peroxides are a group of compounds with the structure , where R = any element. The group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable.
The most common peroxide is hydrogen p ...
s such as urea perhydrate solutions and pH-
buffered 0.1 – 0.25% peracetic acid solutions,
*
alcohols with or without antiseptic additives, used mainly for skin antisepsis,
*weak
organic acids such as
sorbic acid,
benzoic acid
Benzoic acid is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin ...
,
lactic acid
Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as nat ...
and
salicylic acid
*some
phenol
Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it r ...
ic compounds, such as
hexachlorophene,
triclosan
Triclosan (sometimes abbreviated as TCS) is an antibacterial and antifungal agent present in some consumer products, including toothpaste, soaps, detergents, toys, and surgical cleaning treatments. It is similar in its uses and mechanism of act ...
and Dibromol, and
*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
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a sub ...
nature.
Antibiotics
Bactericidal
antibiotics kill bacteria;
bacteriostatic antibiotics slow their growth or reproduction.
Bactericidal antibiotics that inhibit cell wall synthesis: the
beta-lactam antibiotics (
penicillin
Penicillins (P, PCN or PEN) are a group of β-lactam antibiotics originally obtained from '' Penicillium'' moulds, principally '' P. chrysogenum'' and '' P. rubens''. Most penicillins in clinical use are synthesised by P. chrysogenum usin ...
derivatives (
penam
Penams are the primary skeleton structures that define the penicillin subclass of the broader β-lactam family of antibiotics and related compounds. They are bicyclic ring systems containing a β-lactam moiety fused with a five-member thiazoli ...
s),
cephalosporins (
cephem
Cephems are a sub-group of β-lactam antibiotics including cephalosporins and cephamycin
Cephamycins are a group of β-lactam antibiotics. They are very similar to cephalosporins, and the cephamycins are sometimes classified as cephalosporins.
...
s),
monobactams, and
carbapenem
Carbapenems are a class of very effective antibiotic agents most commonly used for the treatment of severe bacterial infections. This class of antibiotics is usually reserved for known or suspected multidrug-resistant (MDR) bacterial infections. S ...
s) and
vancomycin
Vancomycin is a glycopeptide antibiotic medication used to treat a number of bacterial infections. It is recommended intravenously as a treatment for complicated skin infections, bloodstream infections, endocarditis, bone and joint infection ...
.
Also bactericidal are
daptomycin,
fluoroquinolones,
metronidazole
Metronidazole, sold under the brand name Flagyl among others, is an antibiotic and antiprotozoal medication. It is used either alone or with other antibiotics to treat pelvic inflammatory disease, endocarditis, and bacterial vaginosis. It is ...
,
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.
Somewhere 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
nanopillar
Nanopillars is an emerging technology within the field of nanostructures. Nanopillars are pillar shaped nanostructures approximately 10 nanometers in diameter that can be grouped together in lattice like arrays. They are a type of metamaterial, whi ...
s found on the wing releases energy, striking and killing bacteria within minutes, hence called a mechano-bactericidal effect.
In 2020 researchers have combined cationic polymer adsorption and femtosecond laser surface structuring to generate a bactericidal effect against both gram-positive ''Staphylococcus aureus'' and gram-negative ''Escherichia coli'' bacteria on borosilicate glass surfaces, providing a practical platform for the study of the bacteria-surface interaction.
See also
*
List of antibiotics
*
Microbicide
An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ...
*
Virucide
References
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