Lecture 7 - Control of Microbial Growth Flashcards
Asepsis
refers to the absence of significant contamination
Sepsis
refers to significant contamination
Who introduced antisepsis techniques into medical practice by having doctors wash hands with Calcium Hypochloride.
Ignaz Semmelweis
Why were so many women dying after childbirth in Semmelweis’s maternity ward?
The medical students were not washing their hands between doing vaginal exams on dead patients and doing vaginal exams on women in labor.
Known as “The Savior of the Mothers”
Ignaz Semmelweis
Phenol AKA
Carboxylic Acid
Introduced the use of phenol in surgeries
Joseph Lister
Sterilization
killing all forms of microbes on non-living objects
Antisepsis Techniques
killing microbes (including potential pathogens) on living tissues
Disinfections
destroying mirobes (not including endospores) on non-living surfaces
Using an alcohol wipe to remove microbes from a small area of skin is referred to as ______.
Degerming
Washing hands with soap is an example of _______.
Degerming
Why does soap work to remove germs?
soap is made of ampipathic molecules with a polar and non-polar side allowing it to bind to both the water and the oils so germs stuck in the oil can be lifted and washed away
nosocomial infections
infections aquired at a hospital or during healthcare treatment
What microbe is a common cause of nosocomial infections?
Pseudomonas aeruginosa
Is Pseudomonas aeruginosa Hemolytic?
Yes, it is beta-hemolytic and will completely destroy RBCs
RBC
Red Blood Cells
WBC
White Blood Cells
Is Pseudomonas aeruginosa Gram Positive or Negative?
Gram-Negative
Why is Pseudomonas aeruginosa so difficult to destroy?
It is magnesium in the outer membrane which aids in very strong bonds between the lipopolysaccharide molecules making it resistant to penetration by antiseptic compounds
Name a few things that are effective in destroying Pseudomonas
- Acids
- Glutaraldehyde
- Silver
- Strong Phenolic Disinfectants
-static / -stasis
stop/stand still
3 Main Targets of Microbial Control Agents
- Plasma Membrane
- Intracellular Proteins (i.e. enzymes)
- Nucleic Acids (i.e. DNA/RNA)
-cide
to kill
3 Main Methods of Damaging Microbes
- Heat
- Chemicals
- Radiation
Factors Affecting the Rate of Microbial Death
- Number of Microbes
- Presence of Organic Debris
- pH
- Temp
- Nature of Suspending Medium
- Time of Exposure
- Characteristics of the Microbe Being Attacked
Desiccation
creating a hypertonic environment to dehydrate cells
Is desication effective against endospores?
No
Is desiccation effective against viruses?
No
Is desiccation effective against most bacteria?
Yes
Why are low temps effective against microbes?
It decreases the metabolic rate against most microbes so they cannot grow or produce toxins easily
Thermal Death Point
the lowerst temperature at which all microbes in a suspension can be killed in 10 minutes
Thermal Death Time
the minimum length of time it would take to kill all bacteria in a liquid culture at a certain temp
Dismal Retention Time
the length of time it will take to kill 90% of microbes in a suspension at a given temp
How long should something boil to kill most of the microbes?
10 minutes
How resistant are endospores to boiling?
It depends on the type of endospore, but some Hepatitis endospores can survive 30 minutes of boiling and other endospores can survive almsot a full day of boiling