Control of Microbial Growth and Antimicrobial Drugs

Comprehensive vocabulary flashcards covering microbial control terminology, physical and chemical methods of control, antibiotic mechanisms, resistance, and treatments for eukaryotic and viral pathogens.

Sterilization

The removal or destruction of all living microorganisms, including endospores.

Commercial sterilization

Limited heat treatment intended to kill endospores of Clostridium botulinum in canned food.

Disinfection

Control directed at destroying vegetative pathogens on inert surfaces and objects (fomites).

Antiseptic

A disinfectant specifically used for treatment of living tissue.

Degerming

The mechanical removal of microbes from a small area of living tissue, such as through handwashing or an alcohol swab.

Sanitization

A treatment intended to lower microbial counts to safe public health levels and minimize the chance of disease transmission.

Bacteriostatic

A treatment that inhabits the growth or multiplication of bacteria without necessarily killing them.

D-value (Decimal Reduction Time)

The time in minutes taken for an antimicrobial agent to kill $90\%$ of a bacterial population under specific conditions.

Critical items

Medical items that must be sterile because they are used inside the body, such as surgical instruments and IV fluids.

Semi-critical items

Items that require a high level of disinfection, such as dental mirrors and respiratory equipment.

Autoclave

The most effective form of sterilization using steam under pressure; typical settings are $121^{\circ}C$ at $15\,psi$ for $15$ or more minutes.

HTST Pasteurization

High-Temperature Short-Time pasteurization, typically involving heating milk to $72^{\circ}C$ for $15$ seconds.

UHT Pasteurization

Ultra-High-Temperature treatment, where milk is heated to $140^{\circ}C$ for $1$ second to allow for long-term storage.

Lyophilization

A process of freeze-drying involving rapid freezing under vacuum used for the preservation of food, laboratory cultures, or reagents.

HEPA filters

High-efficiency particulate air filters with a $0.3\,\mu m$ pore size used to physically remove microbes from the air in operating rooms or biological safety cabinets.

Ionizing radiation

High-energy radiation (gamma rays, X-rays) that causes double-strand breaks in DNA and creates toxic compounds; used for sterilizing heat-sensitive medical items.

Non-ionizing radiation

Ultraviolet (UV) light which damages DNA by creating thymine dimers; used for surface sterilization and water purification.

Phenols and Phenolics

Chemical agents that disrupt lipids in plasma membranes and denature enzymes; examples include Lysol and Triclosan.

Iodophors

A combination of iodine with an organic molecule, such as Betadine, used as an antiseptic or for water treatment.

Quaternary ammonium compounds (QUATs)

Cationic detergents that disrupt plasma membranes; effective against Gram-positive bacteria but not Pseudomonas.

Ethylene oxide

A gaseous alkylating agent that kills all microbes and endospores; used for sterilizing heat-sensitive items like plastic Petri dishes.

Kirby-Bauer test

The disk-diffusion method used to test the efficacy of antimicrobial agents by measuring the size of the zone of inhibition on an agar plate.

Antibiotic

Antimicrobial chemicals produced naturally by organisms that inhibit the growth of another microorganism.

Narrow spectrum

Antibiotics that are highly specific and effective against only certain types of microbes, such as Penicillin G targeting Gram-positive bacteria.

Superinfection

An opportunistic secondary infection, such as C. difficile or Candida, that occurs when broad-spectrum antibiotics kill the normal microbiota.

Penicillin

An antibiotic that inhibits cell wall synthesis by targeting peptidoglycan crosslinks via its beta-lactam ring.

Polymyxin B

A drug that disrupts the plasma membrane of Gram-negative bacteria; used primarily in topical applications to avoid kidney damage.

Tetracycline

A bacteriostatic antibiotic with the widest spectrum of activity; it inhibits protein synthesis by targeting the $30S$ ribosomal subunit.

Rifamycin

An antibiotic that inhibits bacterial RNA synthesis and is used as part of a multidrug regime for tuberculosis.

Sulfonamides (Sulfa drugs)

Antimetabolites that structurally resemble PABA and competitively inhibit the enzyme involved in folic acid synthesis.

Beta-lactamase

An enzyme produced by some bacteria that provides resistance by breaking down the beta-lactam ring of penicillin.

Phage therapy

An antibacterial treatment using bacteriophages to cause the lysis of bacterial cells.

Miconazole

An antifungal drug that disrupts ergosterol synthesis in the plasma membrane; commonly used for vaginal Candida infections.

Ivermectin

An anti-helminthic drug that blocks neuronal transmission via invertebrate-specific chloride channels, leading to paralysis and death of worms.

Acyclovir

An antiviral drug that resembles a nucleoside (deoxyguanosine) and blocks viral DNA synthesis by inhibiting DNA polymerase.

Neuraminidase inhibitors

Antiviral drugs like Tamiflu and Relenza that block the enzyme required for the release of influenza virus from host cells.