Exam 3

Micro Bio 251 CSN

Contributions of Ignaz Semmelweis & Joseph Lister

Ignaz Semmelweis

• Established Handwashing practice used today

Joseph Lister

• Established techniques of aseptic surgery that were widely adopted around the world, creating a path towards safe surgery

Antisepsis vs. Disinfection

Antisepsis

• Used to reduce microbes numbers on living tissue ( like on skin)

• ex: Alcohol, Hydrogen Peroxide etc.

Disinfection

• Reduced microbes numbers on non-living surface or material

• ex: Bleach, ammonia

Purpose:

Control growth of microorganisms outside the body

Prevent the spread of infections disease by cleaning environment

Most Susceptible vs. Most Resistant

Some types of microbes are more susceptible than others to antiseptics and disinfectants

• Bacteria endospores vs. Nonenveloped viruses

  Witch would be more easier to kill? - nonenveloped

• Which will be the hardest to sterilize kill and removing all the microorganism - endospore

Sterilization meaning

The removal or destruction of all living microorganisms (including spores and endospores)

Common methods:

• Heating

• Filtration

• Sterilization gases

Disinfection

Destroy most microorganisms, particularly pathogens on a non-living surface

• Disinfectant

Antisepsis

Destroy most microorganisms, particularly pathogens on a living surface ( like skin)

• antiseptic

**Preventing of infection or sepsis by removing and decrease bacteria on skin and mucous membrane.

Sanitization

Decrease number of microorganisms that meets specific public health standards

• Sanitizer

Degerming

Degerming - Process of removing microorganisms by mechanical means rather than killing the microbes outright

• Handwashing is a common and effective degerming technique

Bacteriostatic

Inhibits the growth of bacteria but does not kill bacteria, If a bacteriostatic agent is removed, the bacteria may begin growing again

Bactericidal

Kills bacteria

* (Suicide)

Biocidal / Germicidal

Kills microorganisms ( general term)

Targets of antimicrobial agents

Targets:

Cell walls

Cell Membrane or viral envelope

Proteins

Nucleic Acids

Factors that affect death rate of Microbes

• Number of microorganisms

• Type of microorganisms

• pH and temperature

• Concentration of agents

• Presence of organic matter/chemicals

What are the things to considered for choosing the correct method agent to use?

What is desired result?

What type of material?

What will the material be used for?

Cost-effective?

Safe?

Moist Heat

Lower temperatures and shorter exposure time, coagulation and denaturation of proteins

Dry Heat

Moderate to high temperatures dehydration, denaturation of protein, oxidation of cellular components, incineration

Autoclaving

Preferred method of sterilization with moist heat in the healthcare field

Related to moist heat

Boiling

Needs much more time to destroy endospores so not very reliable

-sanitation

• Moist Heat Related

Pasteurization

Must be sufficient without altering the taste of foods

Quick method

• Related to Moist Heat*

Prevents spoilage

Thermoduric Microbes

• Can survive pasteurization

• Certain microbes are thermoduric ( survive high temps for short times) & survive the pasteurization process

Hot Air Sterilization | Dry Heat

items to be sterilized are placed in an oven 350 F

Flaming: Heat item ( like inoculation loop) over direct flame or in an incinerator

Incineration

Materials ( like biohazard waste) undergo combustion and become ash

Temperatures can reach up too 9032 F

Ionizing Radiation

Wavelength shorter ( less than 1 nm) More energy

• Gamma - Nuclear Reaction

• XRAY

• Wavelength Short

• More Energy

• Strong

• Penetrate through materials

Ionizing radiation can penetrate barriers

Cause lethal double stranded DNA Breaks

Can break DNA molecules apart

Ionize water to form (ROS) oxidative damage to cell

Ionize the water in the cell to create reactive oxygen species (ROS) that then damage the cell’s components.

Nonionizing Radiation

Wavelength longer ( greater than 1 nm) Less energy

• Large wavelength

• Less energy

• Weak

• Does NOT penetrate through materials

Kills cells by inducing formation of pyrimidine dimers in DNA

UV Radiation for Sterilize

Ultraviolet Radiation

• Nonionizing radiation

• Commonly used to disinfect/sterilize medical and scientific equipment

• Cause molecular lesions in DNA

  • Poor Penetration

Filtration

• Physical

• Level of disinfection

• or sterility based on pore

• size of filter

Filtration - Filter Liquid

Air Filter - FIlter Air

Chemical agents used for Control Growth

Chemical agents are commonly used to disinfect or sanitize surface, in laboratories and home

Chemical agents do not sterilize, mostly only reduce the number of microbes ( microbial load) by sanitization

Levels of Chemical Decontamination

High-Level Germicides - kill endospores; can sterilize if used correctly

Intermediate- Level - Kills all organisms except endospores ( and fungal spores)

Low- Level - Eliminate only vegetative bacteria, vegetative fungal cells, and some viruses.

Degerming

Most common and easiest ways to degerm is to wash our hands with soap, which allows mechanical removal of microbes

• Microbes do not die from determine with soap

Levels of chemical decontamination

Soaps and detergents - are amphipathic

contains both a polar and nonpolar end

Mechanism of action soap

• Soap doesn’t kill microbes - just helps dislodge them from the surface

• Micelle “lifts” bacteria away from the surface

4 Types of Antimicrobial drugs

Antimicrobial drugs: Synthetic substances that interfere with the growth of microbes

• Antibacterial drugs (antibiotics)

• Antiviral drugs

• Antifungal drugs

• Antiprotozoan & Antihelminthic

Antibiotics

An antimicrobial agent used to treat bacterial infections

Natural antibiotic

Antibiotic that is produced by a microorganisms ( from nature)

ex: Penecillin

Semi Synthetic Antibiotic

Natural antibiotic that has been altered in the lab

Synthetic Antibiotic

Antibiotic that is used completely synthesized in a lab ( found naturally at all)

Selective Toxicity

Selective destroying pathogens without damaging the host

High Selective Toxicity: Highly specific for microorganisms ( little toxicity to humans)

Low Selective Toxicity: Not very specific for microorganisms and cause toxicity and adverse side effects in humans

Who discovered Penicillin

Ernest Duchesne (1896)

Narrow spectrum antibiotics

Affects a narrow range of microbial types

Broad-Spectrum Antibiotics

Affects a broad range of gram-positive and gram- negative bacteria

Superinfection

secondary infection occurring during or immediately after the initial infection by microorganism that is not sensitive to previous antibiotic use for treatment

*when you don’t finish your antibiotics cause reinfection

Bactericidal

Kill bacteria directly

Bacteriostatic

Prevent bacteria from growing

immune system usually destroy microbes

How exactly do antibiotics affect bacteria?

5 Different types

• Inhibition of cell wall synthesis

• Inhibition of protein synthesis

• Inhibition of nucleic acid replication and transcription

• Disruption of cellular ( plasma) membrane

• Inhibition of essential metabolite synthesis

Inhibiting cell wall

Antibiotics prevent the synthesis of intact peptidoglycan weakening the cell wall, and causing the cell to lyse apart

PBP = Penecillin- Binding Protein

(Protein that synthesize or modify cell wall)

• Inhibit cell wall synthesis, modification result in cell lyse due to osmotic stress.

Cell wall inhibition : inactive enzyme

Antibiotics ( Penicillin) block enzymes such as PBP that are responsible for cross linking the layers of peptidoglycan

• The antibiotic binds the active site of PBP enzyme and prevents the enzyme from functioning properly

Effects of Compromised cell walls

The bacteria cell wall is weakened and unable to provide rigid support for the cell wall

Ultimately growing the cell lyse and dies

• weakens the cell wall till burst

Inhibition of protein synthesis

antibiotics can inhibit the synthesis of proteins by binding to different sites of the ribosome, preventing the ribosome from doing it’s job

• Cell can not maintain it’s self without new proteins

  • Antibiotics bind to large or small subunit of ribosomes (70s)

Inhibition of nucleic acid, & replication & transcription

Some antibiotics interfere with the process of DNA replication and transcription

• No RNA synthesis ( transcription inhibited)

• No DNA synthesis ( DNA replication inhibited)

• Antibiotics bind to enzymes inhibit activity

Plasma membrane Disruption

Antibiotics inserted into membrane can cause it to fall apart

• leak important metabolites

Commonly low selective toxicity

Inhibit essentials metabolite synthesis

These antibiotics inhibit the activities of important enzymes by competitively binding to the enzyme - blocking substrates

ex: Sulfa Drugs ( inhibit the folic acid which is necessary making proteins and DNA and RNA

• antibiotics bind and inhibit enzymes in metabolic pathways needed by bacteria

Antifungals

Funny are Eukaryotic

Difficult to find drugs that selectively kill or inhibit the growth of fungi

• Not many available

Mechanisms of Acton

How they can destroy them

• Disruption of cell membrane (Ergosterol)

• Inhibit synthesis of fungal cell wall ( Chitin & Glucans)

• Inhibit synthesis of nucleic acids

Antivirals

Viruses are difficult to target because they use the host own cellular machinery to replicate themselves

Difficult to develop drugs against viruses

Mechanisms to prevent (infection)

• Prevent Entry/ Penetration

• Block Nucleic acid synthesis - replication

• Block Assembly maturation

Antiprotozoan & Antihelminthic

Protozoan parasites and helminths are most difficult to treat

Helminths are parasitic worms, like flukes, tapeworms, and round worms

• Difficult to target because they are eukaryotic (like animals)

• To much like humans