Module 5 microbiology

Moist Heat - Boiling

Oldest method of killing vegetative cells and some viruses, less effective at killing endospores.

Pasteurization

Kills pathogens and reduces the number of spoilage causing microbes while maintaining food quality.

High Temperature Short Time (HTST)

Exposes milk to a temperature of 72°C for 15 seconds which lowers bacterial numbers while preserving the quality of the milk.

Ultra High Temperature Pasteurization

Exposed to a temperature of 138°C for 2 seconds, milk can be stored for a long time in sealed containers without being refrigerated.

Autoclaving

Most effective method of sterilization, raises temperatures above the boiling point of water to sterilize items, killing vegetative cells, viruses, and endospores.

Ionizing Radiation

Includes X-rays, gamma rays, and high-energy electron beams, strong enough to pass into the cell, altering molecular structures and damaging cell components.

Non-ionizing Radiation (UV)

Commonly used for sterilization, uses less energy, does not penetrate cells or packaging, causes thymine dimers to form, leading to mutations that can ultimately kill microorganisms.

Desiccation

Item is rapidly frozen and placed under vacuum so that water is lost by sublimation, removing the water.

Antiseptics

Antimicrobial chemicals safe for use on living skin or tissues.

Disinfectants

Inactivates most microbes on the surface of a fomite using antimicrobial chemicals or heat; should be fast acting, stable, easy to prepare, inexpensive, and easy to use.

Sterilization

The complete removal or killing of all vegetative cells, endospores, and viruses from the targeted item or environment.

High Level Decontamination

Eliminates all microorganisms including endospores.

Intermediate Level Decontamination

May kill fungal spores, but kills vegetative cells, fungi, and bacteria, and viruses; does not kill spores.

Low Level Decontamination

Kills most vegetative bacteria, some viruses, and some fungi; does not kill spores.

Alcohols

Act as surfactants dissolving membrane lipids and coagulating proteins of vegetative bacterial cells and fungi; classified as intermediate level.

Chlorohexidine

Surfactant and protein denaturant; classified as low to intermediate level.

Phenolics

Disrupt cell walls and membranes and precipitate proteins; classified as low to intermediate level.

Filtration

High efficiency particulate air filters (HEPA) have pore sizes small enough to capture bacterial cells, endospores, and many viruses as air passes through these filters.

Factors Affecting Death Rate

Microbe number, nature of microbes, temperature and pH, dosage of agent, mode of action.

Thermal Death Time

The length of time needed to kill all microorganisms in a sample at a given temperature.

Cellular Targets of Physical and Chemical Agents

Includes the cell wall, cell membrane, and protein and nucleic acid synthesis.

Objectives for Physical and Chemical Control

Know factors involved in controlling microbes that may influence the means of control and likelihood of success.

Surfactants

Substances that reduce surface tension and can disrupt microbial membranes.

Disruption of Metabolism

Actions that can control microbes by interfering with their metabolic processes.

Inactivation of Proteins

Processes that can lead to the loss of protein function in microorganisms, contributing to their death.

sanitization

the process of reducing the number of microorganisms to a safe level

disinfection

the process of eliminating or reducing harmful microorganisms from inanimate objects and surfaces

antisepsis

the process of preventing infection by inhibiting the growth of infectious agents

degermation

the process of reducing the number of microorganisms on the skin or mucous membranes

bactericidal

substance that have the ability to kill bacteria

bacteriostatic

substance that inhibits the growth and multiplication of bacteria without killing them

fungicidal

having the property of destroying or inhibiting the growth of fungi

fungistatic

inhibiting the growth of fungi

germicidal

having the ability to kill germs or microorganisms such as bacteria, viruses and fungi

sporicidal

tending to kill spores

antimicrobial

drugs are produced naturally or synthetically reduces microbial numbers

antibiotics

anti-bacterial, natural origin

synthetic drug

control infections by functioning as antimetabolites, competitive inhibitors for bacterial metabolic enzymes. artificially modified from naturally occurring drugs

narrow spectrum

only targets specific subsets of bacterial pathogens

broad spectrum

targets a wide variety of bacterial pathogens

B-lactams

block the crosslinking of peptide chains during the biosynthesis of new peptidoglycan in the bacterial cell wall

Penicillinase

a specific type of β-lactamase, is ineffective against β-lactam antibiotics by destroying their β-lactam ring

Narrow Spectrum Penicillin's

penicillin G and penicillin V, are antibiotics that are primarily effective against a limited range of bacteria

Broad Spectrum Penicillin's

antibiotics effective against a wide range of bacteria, including both Gram-positive and many Gram-negative organisms

Toxicity

the amount of medication given during a certain time interval is the dosage, and it must be determined carefully to ensure that optimum therapeutic drug levels are achieved at the site of infection without causing significant side effects

Cephalosporins

Contain a beat lactam ring and block the transpeptidase activity of penicillin binding proteins

Vancomycin

a member of a class of compounds called the glycopeptides inhibits cell wall biosynthesis and is bactericidal

Bacitracin

A group of structurally similar peptide antibiotics that block the activity of a specific cell-membrane molecule responsible for the movement of peptidoglycan precursors from the cytoplasm to the exterior of the cell.

Amphotericin

An antibiotic used for systemic fungal infections.

Rifampin

An antibiotic that functions by blocking RNA polymerase activity in bacteria, providing selective toxicity against bacterial cells.

Nucleoside analogs

Compounds that inhibit nucleic acid biosynthesis.

Aminoglycosides

Large, highly polar antibacterial drugs that bind to the 30S subunit of bacterial ribosomes, impairing proofreading ability and causing production of faulty proteins.

Tetracyclines

Bacteriostatic drugs that inhibit protein synthesis by blocking the association of tRNAs with the ribosome during translation.

Chloramphenicol

An antibiotic that binds to the 50S ribosome, inhibiting peptide bond formation.

Macrolides - Erythromycin

An antibiotic that prevents translocation during protein synthesis.

Sulfonamides

Antibiotics that inhibit the enzyme involved in the production of dihydrofolic acid, blocking bacterial biosynthesis of folic acid.

Trimethoprim

A structural analogue of dihydrofolic acid that inhibits a later step in the metabolic pathway and is used in combination with sulfa drugs.

Natural selection

A factor contributing to antibiotic resistance.

Health care mentality

A factor contributing to antibiotic resistance.

Agriculture

A factor contributing to antibiotic resistance.

Worldwide resistance

A factor contributing to antibiotic resistance.

Limiting access of the antibiotic

A mechanism of antibiotic resistance that occurs via mutation or acquisition.

Outer Membrane Porins

Channels that can exhibit selectivity and/or altered concentrations to limit antibiotic access.

Active Efflux

A mechanism that actively transports an antimicrobial drug out of the cell, preventing accumulation to antibacterial levels.

Reduced uptake across cytoplasmic membrane

Modification of the bacterial cell membrane to reduce permeability for certain antibiotics.

Enzymatic Inactivation of the drugs

A mechanism of antibiotic resistance often occurring via acquisition.

β-lactamases

Enzymes that break down β-lactam antibiotics by cleaving the β-lactam ring, rendering the drug ineffective.

Modifying enzymes

Enzymes that chemically modify antibiotics so that the drug can no longer bind to its target.

Modification or protection of target

A mechanism of antibiotic resistance where bacteria change or protect the site where the antibiotic normally binds.

Mechanism 4

Change in metabolic pattern/pathway

Spontaneous mutation

Mutations in the genes encoding antibacterial drug targets, bacteria have an evolutionary advantage that allows them to develop resistance to drugs.

Transfer of resistance

Bacteria can share antibiotic resistance genes with each other, allowing resistance to spread quickly between different bacterial species.

Transduction

Resistance genes are transferred from one bacterium to another by bacteriophages (viruses that infect bacteria). The phage accidentally carries bacterial DNA, including resistance genes, and injects them into another bacterial cell.

Transformation

Some bacteria can take up free DNA fragments (including resistance genes) directly from their environment. This DNA often comes from dead bacterial cells that have released their genetic material.

Conjugation

This is the most common and efficient method of resistance transfer. It occurs when two bacteria connect through a pilus (a tube-like structure) and transfer plasmids—small, circular pieces of DNA that often carry multiple antibiotic resistance genes.

Normal flora

Beneficial microbes that live naturally on and inside the human body and help protect against harmful pathogens, aid digestion, and support the immune system.

Transient flora

Microbes that are present only temporarily. They may come from the environment or contact with other people but do not permanently stay on the body.

Resident flora

Microbes that live more permanently in or on certain areas of the body and are well adapted to those environments.

True pathogens

Microorganisms that can cause disease in healthy individuals with a normal immune system.

Education is vital

Patients can't demand drugs and must take their full prescription.

Using combinations of drugs

Can help slow the spread of drug resistant pathogens.

Sites of Bacterial action

Locations where antibiotics exert their effects.

Mode of action

How antibiotics work to inhibit or kill bacteria.

Bacteriocidal vs. bacteriostatic

Bacteriocidal kills bacteria while bacteriostatic inhibits their growth.

Spectrum of activity

The range of bacteria that an antibiotic can affect.

Natural vs. synthetic

Refers to whether antibiotics are derived from natural sources or artificially created.

Use - Advantages vs. Disadvantages

Considerations regarding the benefits and drawbacks of antibiotic use.

Opportunistic pathogen

which can infect the skin tissue surrounding the wound and possibly spread to deeper tissues.

Portal of Entry

route through which a pathogen enters the body to establish an infection.

Exogenous

when the infectious agent comes from an outside source, such as the environment, another person, or an animal.

Endogenous

when the infectious agent already exists inside the body, such as from the normal flora that becomes harmful if it enters a sterile area.

Size of inoculum (infectious dose)

refers to the number of microorganisms required to cause infection. The smaller the infectious dose, the more infectious the organism is.

Attachment to host

the process by which a pathogen adheres to the host's tissues.

Invasion

the process by which a pathogen invades tissues to multiply and spread.

Virulence factors

molecules that help microbes overcome the body's defenses.

Exoenzymes

enzymes secreted by microbes that break down host tissues and barriers, helping the pathogen spread through the body.

Hyaluronidase

an exoenzyme that breaks down connective tissue.

Coagulase

an enzyme that causes blood to clot, protecting bacteria from immune cells.

Toxins

poisonous substances produced by microbes that damage host cells or disrupt normal functions.

Exotoxins

proteins secreted by bacteria into surrounding tissues, typically from Gram-positive bacteria.