The killing or removal of all viable organisms from a growth medium or surface including endospores and viruses
Decontamination
The treatment of an object or surface to make it safe to handle
Disinfection
Directly targets pathogens although it might not eliminate all microorganisms
Methods for inhibiting rapid microbial growth
Sterilization
Decontamination
Disinfection
Disinfectants
Specialized chemical or physical agents that can kill microorganisms or inhibit microbial growth
Microbial control in vivo is much more difficult
Bactericidal agents
Killmicroorganisms
Bacteriostatic agents
Inhibit microbial growth
Bacteriolytic agents
Some bactericidal agents are also bacteriolytic agents
Depending on the type of microorganism or pathogen to be controlled, the terms can also be applied to fungi (e.g., fungicidal) and viruses (e.g., viricidal)
Minimuminhibitoryconcentration (MIC)
Determines the smallest amount of agent needed to inhibit the growth of the test organism
Diskdiffusion technique
A technique for measuring antimicrobial activity
Categories of chemical antimicrobial agents
Antimicrobial products used to control microorganisms in industrial and commercial environment
Products designed to preventgrowth of human pathogens in inanimate environments and on external body surface
Sterilants
Destroy all forms of microbial life, including endospores
Disinfectants
Kill microorganisms but not necessarily endospores and are used on inanimate objects
Sanitizers
Agents that reduce but may noteliminatemicrobial numbers to levels considered to be safe
Antiseptics and germicides
Chemical agents that kill or inhibit growth of microorganisms and that are nontoxic enough to be applied to living tissue
Only sterilants are effective against bacterial endospores
Some bacteria such as Mycobacterium tuberculosis are resistant to the action of common disinfectants because of the waxy nature of their cell wall
Categories of antimicrobial agents
Synthetic agents
Antibiotics
Selective toxicity
Ability to inhibit or kill a pathogen without affecting the host
Growth factor analogs
Structurally similar to growth factors but donotfunction in the cell
Growth factor analogs
Analogs similar to vitamins, amino acids, and other compounds
Sulfa drugs
First widely used growth factor analogs that inhibit growth of bacteria
Isoniazid
A growth analogeffectiveonly against Mycobacterium that interferes with synthesis of mycolic acid, a mycobacterialcellwallcomponent
Nucleicacid base analogs
Have been formed by the addition of bromine or fluorine atom to block nucleic acid synthesis, used in treatment of viral and fungalinfections
Quinolones
Antibacterial compounds that interfere with DNA gyrase, preventing the supercoiling of DNA
Antibiotics
Naturally occurring antimicrobial drugs produced by microorganisms
The majority of antibiotics (>99%) are not clinically useful without structural modifications in the laboratory, a process that creates semi-synthetic antibiotics
Broad-spectrum antibiotics
Find wider medical use than narrow-spectrum antibiotics
Novel antibiotics continue to be discovered and/or synthesized by modifying current drugs
β-Lactam antibiotics
One of the most important groups of antibiotics, including penicillins and cephalosporins, over halfofallantibioticsused worldwide
Penicillins
Discovered by Alexander Fleming, primarily effective against gram-positive bacteria, some synthetic forms are effective against some gram-negative bacteria, target cell wall synthesis
Cephalosporins
Produced by fungus Cephalosporium, same mode of action as the Penicillins, commonly used to treat gonorrhea
Aminoglycosides
Useful against Gramnegative bacteria, target the 30Ssubunit of the ribosome, not commonly used today due to neurotoxicity and nephrotoxicity
Macrolides
Example: erythromycin, broad-spectrum antibiotic that targets the 50S subunit of ribosome
Tetracyclines
Widespread medical use in humans and animals, broad-spectrum antibiotics, inhibiting almost all gram-positive and gram-negative bacteria, inhibits functioning of 30S ribosomal subunit
Daptomycin
Depolarizes bacterial cell membranes and is used mainly againstgram-positive bacteria
Platensimycin
Inhibits a key enzyme in bacterial fatty acid biosynthesis, thus disrupting lipid biosynthesis
Antimicrobial drug resistance
The acquired ability of a microorganism to resist the effects of an antimicrobial agent to which it is normally susceptible