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Assignment for Lab8   Question 1

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Assignment for Lab8

 

Question 1.

 

 

 

Disk #	Name	Observations
1	3% H2O2	Hydrogen peroxide disinfectants had the largest zone of inhibition and are effective against Staphylococcus aureus and Pseudomonas aeruginosa biofilms.
2	10% Clorox	This shows least zone of Inhibition around Staphylococcus aureus and Pseudomonas aeruginosa. Therefore there were no growth of bacteria.
3	1% Vesphene	Vesphene kill a broad spectrum of the three bacteria without harming the surface. However, S.aureus had the largest zone of inhibition and most effective.
4	70% alcohol	H2O2 act on both disinfectant . S. aureus forms biofilms in the presence of alcohol
5	1:1000 zephyr chloride	Chlorine was effective against all three bacterial strains. S. aureusshows the largest zone of inhition Ecoli had the smallest zone of inhibition
6	Water (negative control)	Negative control does not only inhibits growth on bacteria and does not  kill bacteria

 

A.Based on your results, which disinfectant(s) worked best against the bacteria you tested?

Chlorine

 

Question 2 : Do you think that a disinfectant or antiseptic that works well on an agar plate always works well in a real-world setting?  Why or why not?

No, disinfectants and antiseptics often work on the agar plate and provide nourishment in agar. But this  is not possible in real world.

 

Question 3 : You are asked by your place of employment to order a disinfectant that will be used for daily cleaning. What are some of the factors that you will consider when choosing which one to order?

Some of the factors that should be consider when choosing disinfection in healthcare facilities are : Time of action, safety, microbe range, penetration, preparation, cost, and odor.

1. Relevant Kill Claims: Disinfectant products should be effective against the microorganisms that are the most common causes of HAI and outbreaks. The authors recommend that facilities select disinfectants that are EPA-registered to kill as many pathogens.

2. Time of action:Drs. Rutala & Weber emphasize that a surface must remain wet as the disinfectant’s contact time in order to effectively kill microorganisms.  Also stated, “Fast kill times are important because most healthcare- associated pathogens before the disinfecting solution can dry or be removed and before patients or staff are likely to retouch the surface.

3. Safety

The authors note several user and surface safety components. Facilities should pay close attention to toxicity signal word, flammability ratings and personal protective equipment (PPE)

requirements when evaluating disinfectants. Secondly, facilities should select surface disinfectants that are compatible with common healthcare surface materials to ensure routine product usage will not cause surface damage.

4. Ease of Use

Disinfection effectiveness in the presence of organic matter and good cleaning properties to effectively reduce bioburden on surfaces. Additionally, clear directions for use (DFU), acceptable odor profile and availability of multiple product forms can also contribute to compliant usage.

 5.  Cost and odor

• the cost must be taken in consideration including product capabilities, infection cost, and cost per use

 

Questions 4-7.

 

After watching the video and reading the article, answer the following questions carefully.

 

Question 4.Why all antibiotic testing should be done in Muller Hinton plates?

Antibiotic testing should be done in Muller Hinton plates because it is an agar that is thoroughly tested for its composition and its pH level. Also, using this agar ensures that zones of inhibitions can be reproduced from the same organism, and this agar does not inhibit sulfonamides.  The agar itself must also only be 4mm deep. 

 This further Mueller-Hinton  a non-selective, non-differential medium. This means that almost all organisms plated  will grow.

?  It contains starch that  absorb toxins released from bacteria, so that they cannot interfere with the antibiotics. It also mediates the rate of diffusion of the antibiotics through the agar.

?  It is a loose agar that allows for better diffusion of the antibiotics than most other plates. A better diffusion leads to a truer zone of inhibition.

?  MHA shows  the best medium acceptable reproducibility for susceptibility testing (American society for Microbiology).

 

Question 5.Why all tests need to start with pure cultures? ?

All test needs pure culture to allow isolation of a microbe from a mixed culture to obtain a single kind of organism from a mixed culture. 

- Also, contamination could change results of tests performed. Therefore, pure culture allows application of  various tests and identify the bacteria

 

Question 6. Why are standard needed?

 Standards are needed to give guidance on requirement to validate claims. 

Standards allow for minimum requirement for a product to be described as disinfectant. It also ensures that manufactures need to be able to validate claims of bactericidal activity.

 

Question 7. Why all cultures should have the same turbidity? Turbidity is used to measure the cell density of a culture.

 

Questions 8-9

After looking at the results of the experiments done in class and using the charts shown in the powerpoint answer the questions.

 

Question 8

 

 

 

Question 9

 

Pick one antibiotic from each plate.

 

 

Bacterial species	Disk label	Antibiotic/concentration	Zone of inhibition (mm)	Interpretation (R,I,S)
E.Coli		Ampicillin	16	I
		Erythromycin	12	R
		Ciprofloxacin	32	S
		Piperacillin	13	S
s.aureus	AM	Amoxicillin/Clavulanic acid	95mm	S
	E	Erythromycin	25mm	S
	CIP	Ciprofloxacin	25mm	S
		Polymyxin b	9 mm	I
Pseudomonas Aeruginosa		Amikacin(30ug)	7	R
		Erythromycin	7	R
		Ciprofloxacin	27	S
		Piperacillin	13	S

 

 

 

 

 

Question 10

Using the results shown on slide 27 complete the following chart.