2. Antimicrobials:
• The word antimicrobial was derived from the Greek words anti (against), mikros (little) and bios (life) and
refers to all agents that act against microbial organisms.
• The term “antimicrobials” include all agents that act against all types of microorganisms – bacteria
(antibacterial), viruses (antiviral), fungi (antifungal) and protozoa (antiprotozoal).
• A similar term derived from the Greek word anti (against) and biotikos (concerning life).
• “Antibiotic” refers to substances produced by microorganisms that act against another microorganism.
3. Antibiotics Versus Antimicrobials
• An ANTIBIOTIC is a low molecular substance produced by a microorganism that at a low
concentration inhibits or kills other microorganisms.
• An ANTIMICROBIAL is any substance of natural, semisynthetic or synthetic origin that kills
or inhibits the growth of microorganisms but causes little or no damage to the host.
• All antibiotics are antimicrobials, but not all antimicrobials are antibiotics.
4. CLASSIFICATION ACCORDING TO SPECTRUM OF ACTIVITY.
Broad spectrum antibacterials are active against both Gram-positive and
Gram-negative organisms.
Examples: tetracyclines, phenicols, fluoroquinolones, cephalosporins.
Narrow spectrum antibacterials have limited activity and are primarily only
useful against particular species of microorganisms.
Example: glycopeptides and bacitracin are only effective against Gram-
positive bacteria, whereas polymixins are usually only effective against Gram
negative bacteria. Aminoglycosides and sulfonamides are only effective
against aerobic organisms, while nitroimidazoles are generally only effective
for anaerobes.
5. Infections and diseases may be caused by different
types of organisms like bacteria, fungi, and viruses,
etc., in humans and animals. The drug used to
prevent the pathogenicity of microorganisms is
called an antimicrobial agent.
6.
7. Antibacterial drug: A drug that is used to inhibit the
pathogenic activity of bacteria is called as antibacterial
drugs. Example: Zithromax.
Antifungal drug: A drug that is used to prevent the
fungal activity in the host is called an antifungal drug.
Example: Miconazole
Antiviral agent: A drug which is used to stop the
pathogenic action of a virus is called as antiviral agents.
Example: Tamiflu.
Antiparasitic drug: A drug that is used to prevent the
growth of pathogenic parasites. Example: Anthelmintics
8. Effect on Bacteria
Bactericidal drugs are those that kill target organisms.
Examples of bactericidal drugs include aminoglycosides, cephalosporins,
penicillins, and quinolones.
Bacteriostatic drugs inhibit or delay bacterial growth and replication.
Examples of such include tetracyclines, sulfonamides, and macrolides.
Some antibiotics can be both bacteriostatic and bactericidal, depending on
the dose, duration of exposure and the state of the invading bacteria.
For example: aminoglycosides, fluoroquinolones, and metronidazole.
9. Specific enzyme activity
• useful indicator of the response of microorganisms to stress caused in the soil by antibiotics
• indicates the potential of microbial communities to carry out biochemical processes that are essential
to maintain soil quality
• Any application of a toxicant that might affect the growth of soil microorganisms can induce alterations
in the general activity of enzymes, such as dehydrogenases (DHAs), phosphatases (PHOSs), and urease
(URE)
• Benzylpenicillin, tylosin and sulfadiazine inhibited soil DHAs and PHOSs from 35 to 70% compared to
the non-antibiotic amended control (Reichel et al., 2014; Akimenko et al., 2015).
10.
11. Impact on soil function
• Antibiotics may also change the turnover rate of iron in soil.
• Sulfadiazine and monensin blocked Fe(III) reduction in soil over periods ranging from a few days to the
end of a 50-day experiment (Toth et al., 2011).
• sulfadimethoxine inhibited soil nitrification
• A decrease in the nitrification rate caused by a high oxytetracycline concentration (30 mg/kg) and
sulfadiazine (100 mg/kg) in a single application was also observed by Ma et al. (2016) and Kotzerke et
al. (2008)
12. Degradation Rate of Antimicrobes in Soil
• transformation/degradation
• sorption-desorption
• uptake by plants
• runoff and transport into groundwater
14. Antiseptics and Disinfectants
Antiseptics are applied to the injured tissues, cuts, and infected skin surfaces. Antiseptics are not prescribed to be taken orally.
Dettol – It is a mixture of chloroxylenol and terpineol. It is used to apply in the wounds.
Iodine tincture and iodoform – It has very good antiseptic properties.
Boric acid – It is used as an antiseptic agent for eyes.
Disinfectants are used to destroy the pathogenic microorganisms in the nonliving objects such as floors and drainage
systems.
Example: Chlorine and sulphur dioxide at low concentration.
15. Antimicrobial products
Antimicrobial pesticides are substances or mixtures of substances used to destroy or suppress the growth
of harmful microorganisms such as bacteria, viruses, or fungi on inanimate objects and surfaces.
A germicide is a substance or mixtures of substances that kill a number of microorganisms
A sanitizer is used to reduce, but not necessarily eliminate, microorganisms from the inanimate
environment to levels considered safe
Sporicides- Used to inactivate bacterial spores.
