MB 351 - Lecture 19

Question 1

destruction of pathogens on living tissue

Answer 1

antisepsis

Question 2

study of distribution and determinants of health-related states. the branch of medicine that deals with the incidence, distribution, and possible control of diseases and other factors relating to health.

Answer 2

epidemiology

Question 3

17th C hospitals for childbirth become common, and doctor’s would not _________, and would not __________ in between. This caused high numbers of childbed fever/puerperal fever. The most common infection causing puerperal fever is _____________, caused by what?

Answer 3

-wash hands between patients, and would not change clothes -genital tract sepsis (bacterial contamination) caused by contaminated medical equipment or unhygienic medical staff who contaminate the mother’s genital tract during the delivery. -other types of infection that can lead to sepsis after childbirth include urinary tract infection, breast infection (mastitis) and respiratory tract infections -resulted in high death rates of women giving birth in America and Europe prior to the late 1800s.

Question 4

Hungarian physician who is called the “saviour of mothers.” What did he do? Before Robert Koch and Louis Pasteur

Answer 4

Ignaz Philipp Semmelweis (one of the pioneers of antiseptic procedures) -discovered in 1847 that the incidence of puerperal fever could be drastically cut by use of hand washing standards in obstetrical clinics. -introduced washing hands with chlorinated lime solutions, and this reduced the incidence of fatal puerperal fever from about 10 percent to about 1-2 percent

Question 5

At first he was ridiculed for his hypothesis that there was only one cause, that all that mattered was cleanliness. Why was his hypothesis considered extreme?

Answer 5

Ignaz Philipp Semmelweis. He was dismissed from the hospital and harassed by the medical community. Semmelweis’ practice only earned widespread acceptance years after his death, when Louis Pasteur and Robert Koch provided evidence for the germ theory of disease.

Question 6

A British surgeon who was also a pioneer in the control of microbial growth. Awareness of Semmelweis’s work and together with Pasteur’s work, realized the true nature of infectious disease, and used this to help his surgery patients. What did he use to reduce the number of microorganisms on wounds and incisions? He also started doing what in his operating room?

Answer 6

Lord Joseph Lister (1867) -bandages treated with phenol (aka carbolic acid) -started washing everything in his operating room

Question 7

an aromatic organic compound that kills microorganisms by denaturing their proteins and disrupting the cell membrane, used by Lister. How would Lister apply this? The use of this greatly reduced…

Answer 7

phenol (carbolic acid) -spraying the wound with a fine mist of phenol -reduced the rate of infection and mortality of surgery patients, lending further credence to the germ theory of disease.

HOW DOES PHENOL KILL MICROBES?

Question 8

CREDITED for developing the use of antiseptics (compounds used on living tissue to kill microbes), and aseptic surgery (techniques used to minimize microbial contamination). Earned a reputation as the world’s safest surgeon.

Answer 8

Lord Joseph Lister

Question 9

Major problem with phenol?

Answer 9

IRRITATING to eyes and skin, and bad odor. Some forms may cause brain damage in infants.

Question 10

How is phenol still used today?

Answer 10

In throat lozenges and in throat sprays

Question 11

Inspiration for the modern antiseptic mouthwash product _________ . This does not contain _______ , but does contain what?

Answer 11

Listerine - LISTER. Did not develop it, but a way to recognize his work. -does not contain phenol, but does contain eucalyptol, methanol, thymol, etc. which in combination have antiseptic effect

Question 12

Lister introduced these ________ : these are techniques to prevent microbial contamination of what? Where are these techniques also applied?

Answer 12

aseptic techniques: prevent microbial contamination of instruments, lab benches and workstations, patients, surgical rooms. -in work at research labs, the food industry, and pharmaceutical companies that produce medicines and other health products

Question 13

Very specific meaning, which is the complete destruction or removal of ALL viable (living) microorganisms. Frequently achieved by ________ or ________ treatments.

Answer 13

Sterilization. -chemical and physical treatments

Question 14

Most common method used for killing microbes

Answer 14

HEAT

Question 15

Cells that are actively growing or dividing

Answer 15

vegetative cells

Question 16

Highly resistant dormant forms of microbes

Answer 16

endospores

Question 17

The use of physical or chemical agents to inhibit or destroy microbes. Most often one is reducing numbers of pathogens to point where they no longer cause disease. Usually achieved using chemicals

Answer 17

Disinfection

Question 18

Refer to those chemical agents applied to living tissue to kill microbes (alcohol, hydrogen peroxide, betadine solutions)

Answer 18

antiseptics

Question 19

Refer to those chemicals applied to inanimate objects in order to achieve disinfection. These may be too toxic to use on humans or animals (pine oils, bleach, alcohols).

Answer 19

Disinfectants

Question 20

Some chemical agents are both ______ and ________

Answer 20

disinfectants, and aseptics (alcohols can be applied to human tissue, and also to instruments for disinfection)

Question 21

are those chemicals agents that do not kill but only inhibit growth. These are typically inhibitors of some important __________, and what happens if the agent is removed? Some ______ fall into this category.

Answer 21

Bacteriostatic. important biochemical process, such as protein synthesis, and bind relatively weekly; if the agent is removed, the cells resume growing. Antibiotics

Question 22

refers to those chemical agents that kill bacteria. The _________ agents will bind tightly to their cellular targets and by definition, kill the cell. However, dead cells are not usually _________, and total cell numbers reflected in the turbidity of the culture remain constant.

Answer 22

bacteriocidal -lysed

Question 23

chemical agents kill cells by lysing them and releasing their cytoplasmic contents

Answer 23

bacteriolytic

Question 24

antibacterial agents are classified as: ____________ by observing their effects on bacterial cultures using _________ and ________ growth asasays

Answer 24

bacteriostatic, bacteriocidal, bacteriolytic -viable and turbidity

Question 25

Bacteriostatic compounds often have a reversible effect since they do not kill the bacteria, but inhibit growth. What does this growth graph look like? And explain.

Answer 25

It is often reversible, if you remove the bacteriostatic compound, the organism will start to grow again. In this graph, it shows that bacteriostatic compounds when used on a growing population of cells (y axis represents log cell number is increasing) and at a specific point in time (indicated by the arrow), a bacteriostatic agent is used, then the number of microbial cells cease to increase or decrease, it stays the same, your total cell count using a direct microscopic count is the same as the viable cell count (using the plate count method).

Question 26

Examples of bacteriostatic agents:

Answer 26

protein synthesis inhibitors

Question 27

Bacteriocidal agents will prevent growth by killing the cells, it does not destroy/lyse the cells. So what does the graph look like, and explain.

Answer 27

Microbes are still physically there and can be counted, but there is no cell lysis (cells are still intact), so if you were to do a total cell count using a direct microscopic count, it would appear that there was no change in cell number. However, the viable cell count goes down-meaning the number of cells you plate out on an agar plate will decrease since you have killed the cells with your agent, so they will not grow.

Question 28

Bacteriolytic agents will induce killing by cell lysis. Growth graph, and explain. What is an example of a bacteriolytic agent, and what does it do?

Answer 28

During lysis, the cell components are released into the media and there appears to be a dramatic decrease in the total cell count (when a cell lyses, there is no microbial “body” left, and the culture media starts to look less cloudy or turbid). The viable cell count also goes down since there are fewer living cells and thus fewer will grow up on a viable plate count. -penicillin, it stops the enzyme that crosslinks peptidoglycan, the cell wall structure becomes compromised, and the cell goes through osmotic lysis (too much water coming into the cell).

Question 29

When bacterial populations are heated or treated with antimicrobial chemicals, they usually die at a _______ \_\_\_\_\_\_\_\_ . Rates are generally constant on a _____ \_\_\_\_\_ ______ .

Answer 29

- constant rate - on a semi log plot When bacterial populations are heated or treated with antimicrobial chemicals, they usually die at a constant rate. For example, suppose a population of 1 million microbes has been treated for 1 minute and 90% of the population has died. We are now left with 100,000 microbes. If the population is treated again for another minute, 90% of those microbes die, and we are left with 10,000 survivors. In other words, for each minute the treatment is applied, 90% of the remaining population is killed (Table 7.2). Rates are generally constant on a semi log plot: (ie 90% of survivors die per unit time)

Question 30

If the microbial death curve is plotted logarithmically, the death rate is ______ , as shown by the graph. What is the length of time it takes for an antimicrobial treatment to decrease the population by 1 log called? There is a name for this.

Answer 30

- death rate is constant - decimal reduction time (D) - plotting arithmetically is impractical The kinetics of death are very similar to the kinetics of growth, it is influenced by: Population size, the more microbes there are to begin with, the longer it takes to eliminate the entire population (Fig. 7.1, right, high vs. low population load). If the rate of killing is the same, it will take longer to kill all members of a larger population than a smaller one. This is true in both heat and chemical treatments. **Another factor that influences the death rate are environmental influences:** such as temperature, age of cells (old cells are harder to kill, so are endospores). Eg. **The presence of organic matter often inhibits the action of chemical antimicrobials. Microbes in surface biofilms are difficult for microbiocides to reach effectively. A third factor is the time of exposure, chemical antimicrobials often require extended exposure to more resistant microbes or endospores to be affected.**

Question 31

What is the D-value for 50, 60, 70 degrees celcius?

Answer 31

70C D = 3 mins 60C D = 12 mins 50C D = 42 mins

Question 32

Check your understanding:

Answer 32

??

Question 33

Learning Objectives

Answer 33

??

Question 34

antiseptics

Answer 34

Refer to those chemical agents applied to living tissue to kill microbes (alcohol, hydrogen peroxide, betadine solutions)

Question 35

Savior of mothers? And why? He is considered one of the pioneers of antiseptic procedures, but Lister is the one who is credited for developing the use of antiseptics and aseptic surgery.

Answer 35

Ignaz Philipp Semmelweis - bc he discoved by 1847, that the indicence of puerperal fever could be drastically cut by use of hand washing standards in obstetrical clinics. He introduced handwashing with a chlorinated lime solution for interns who had performed autopsies. This immediately reduced the incidence of fatal puerperal fever from about 10 percent to 1-2 percent.

Question 36

Lister earned a reputation as?

Answer 36

the world's safest surgeon

Question 37

sterilization is the complete destruction or removal of ALL viable microorganisms...so this means the destruction of both ______ and _______ .

Answer 37

both vegetative cells and endospores

Question 38

Heat is the most common method for _______ . Whereas, _______ is most commonly achieved using chemicals. What are the two types?

Answer 38

heat most common for killing microbes (sterilization). disinfection - two types are antiseptics and disinfectants

Question 39

How does phenol destroy microbes

Answer 39

aromatic organic compound that kills microorganisms by denaturing their proteins and disrupting the cell membrane

Question 40

phenol (carbolic acid) -spraying the wound with a fine mist of phenol -reduced the rate of infection and mortality of surgery patients, lending further credence to the germ theory of disease. HOW DOES PHENOL KILL MICROBES?

Answer 40

an aromatic organic compound that kills microorganisms by denaturing their proteins and disrupting the cell membrane, used by Lister. How would Lister apply this? The use of this greatly reduced...