Learning activity 6

What category of microbe produces the most commercially available antibiotics?

Actinomycetes (Streptomyces)

Why are protozoan and helminthic infections difficult to treat?

because they are eukaryotes

Inhibition of Nucleic Acid synthesis

Cell cannot undergo binary fission

Inhibition of Cell wall synthesis

The cell undergoes osmotic lysis

Inhibition of the synthesis of Essential Metabolites

Cell undergoes osmotic lysis

Injuring the Plasma Membrane

Cytoplasmic contents leak out

Inhibition of Protein Synthesis

The cell has defective metabolism

Microbial

Means kills microbes

Sterilization

Complete destruction of all microbial life

virucidal

kills or inactivates viruses

bactericidal

kills bacteria

Desiccation

Prevents metabolism

low temperatures

Bacteriostatic

High pressure

Does not alter the important characteristics of Food

Salt and Sugar

Creates a hypertonic environment

Autoclave

Destroys endospores

Pasteurization

Thermoduric organisms survive

Dry heat

kills by oxidation

Nitrates and nitrites

Prevents endospore germination

Filtration

Heat-liable materials

Radiation

Damages DNA

Disinfection

Destroying only harmful microbes

Bacteriostatic

Inhibits, rather than kills microbes

Degerming

Mechanical removal of microbes

Sanitization

Lowering microbe counts to safe levels

Chemotherapy

Using chemicals to treat a disease

Antiseptic

Destroying microbes on living tissues

Sterilization

removing and destroying all microbes

Antibiotic

Produced by microbes to kill microbes

The preservation of beef jerky from microbial growth relies on which method of microbial control?

Desiccation, ionizing radiation

How does the addition or salt or sugar help to preserve food?

They preserve food by drawing water out of microbial cells, causing plasmolysis and stopping metabolism

Regarding contact time, why is diluted ethanol a more effective disinfectant than undiluted ethanol?

Water is required for optimal protein denaturation, so 70% ethanol penetrates cells and denatures proteins better. Undiluted ethanol evaporates too quickly, reducing time to act on microbes

True or False: Sanitization kills all microbes

False

True or False: Pasteurized foods cannot spoil

False

True or False: Autoclaves use moist heat to sterilize materials

True

True or False: Ionizing radiation is not used to preserve food

False

True or False: Quats are not effective against endospores and prions

True

The first antimicrobial drug given, especially when the pathogen is not yet known, is often a ___

Broad-spectrum drug

What best describes a fomite?

An inanimate object that may transmit infectious agents.

Commercial Sterilization

killing Clostridium botulinum endospores from canned goods

Autoclave

steam under pressure, 121*C at 15 psi, kills all organisms and endospores.

Pasteurization

reduces spoilage organisms and pathogens

Thermoduric

organisms survive (Bacillus, Clostridium, and Enterococci)

Dry heat sterilization

Kills by oxidation

Filtration

Passage of substance through a screen-like material, used for heat-labile (heat-sensitive) materials.

Low temperatures

has a bacteriostatic effect

High pressure

Denatures proteins, endospores are usually resistant.

Desiccation

Absence of water prevents metabolism, not always lethal

Osmotic Pressure

uses salts and sugars to create hypertonic environment; causes plasmolysis

Radiation (Ionizing)

Gamma rays easily penetrate paper and plastic

Radiation (nonionizing)

UV light does not penetrate paper or plastic, used to sterilize surfaces

Microwaves

kill by heat; not especially antimicrobial

Phenol, Phenolics, Bisphenols, and Biguanides

Injure lipids of plasma membranes, causing leakage

Alcohols

Denature proteins and dissolves lipids

Antibiotic resistance

Formerly effective medications have less and less impact over time

Antibiotic

a substance produced by a microbe that, in small amounts, inhibits another microbe

Antimicrobial drugs

synthetic substances that interfere with the growth of microbes

Selective toxicity

selectively finding and destroying pathogens without damaging the host

Chemotherapy

the use of chemicals to treat a disease

Biocide (germicide)

treatments that kill microbes

Bacteriostasis

inhibiting, not killing, mirobes

Narrow spectrum of microbial activity

drugs that affect a narrow range of microbial types

Broad-spectrum antibiotics

affect a broad range of gram-positive or gram-negative bacteria

Superinfection

overgrowth of normal microbiota that is resistant to antibiotics

Synergism

the effect of two drugs together is greater than the effect of either alone

Antagonism

the effect of two drugs together is less than the effect of either alone

Persister cells

microbes with genetic characteristics allowing for their survival when exposed to an antibiotic.