CH7 Flashcards
Radiation Types :
- Ionizing Radiation
2. Non-Ionizing Radiation
What the wavelength of Non-Ionizing Radiation ?
Wavelength > 1 nm
Example of Non-Ionizing Radiation
UV Light
Mechanism of non-ionizing radiation
Damage DNA , Thymine dimerization
True or false
Non-Ionizing Radiation does not penetrate plastic, glass or proteinaceous matter
True
Non-Ionizing Radiation Uses
• Used to reduce microbial populations
– hospital rooms
– nurseries
– operating rooms
True or false
Chemical Methods may be used on living organisms
True
Factors that may effect disinfecting
- Concentration of the disinfectant
- What is to be disinfected
• pH
• Organic materials - Contact with microbe (easy or difficult)
- Time to be left on the surface (contact or challenge time)
معلومات قيمة
Phenol coefficient test was the standard test used to compare the
activity of the disinfection with that of phenol
• Now the standard method is Use-Dilution test
.
Methods of Evaluating Disinfectant
- Use dilution test
determine the bacterial survival in recommended dilution of a disinfectant and antiseptics - Disk-diffusion method (مايكرو لاب) look at the inhibition zone
Microbes used in dilution test :
Three microbes are used
Salmonella choleraesuis
Staphylococcus aureus
Pseudomonas aeruginosa
Types of disinfectants
- Phenol
- Chlorine
- Iodine
- Alcohols. Ethanol, Isopropanol
- Heavy Metals. Ag, Hg, Cu
- Aldehydes
- Gaseous Sterilants
- Peroxygens
Types of phenol ?
1.Lister: Phenol
2. Phenolics.
O-phenylphenol used as
surfaces disinfectant
3. Bisphenols:
– Hexachlorophene,
– Triclosan
4. Biguanide :
Chlorhexidine
Phenol uses ?
- Surgical disinfection in operating room
- Irritant to skin and has disagreeable odor
- Used in throat lozenges in low concentration
- Above 1% it has significant antimicrobial effect
Advantages of Phenols as disinfectant
- Remain active in presence of organic compounds
- Stable
- Persist for long periods after application
Difference between Phenolics and phenol
or
عرف Phenolics and give example
derivative of phenol that reduce irritation effect and increase the antimicrobial activity
Example : O-phenylphenol
MOA of Phenolics
injuring the lipid containing plasma membrane, resulted in leakage of cellular content
Phenolics derived from?
Coal tar; group called Cresols
True or False
Phenolics used as surfaces disinfectant
True
True or False
phenolic Active in presence of organic materials like phenol ?
Yes True
Bisphenols effective against Gram +ve or Gram -ve
Gram +ve
Broad spectrum activity
Example of Bisphenols and the uses
a. Hexachlorophene; skin lotions
b. Triclosan: Used in soaps, tooth pastes and mouth wash.
True or False
Biguanide effective against gram-negative bacteria (not pseudomonads)
True
معلومة
Biguanide not sporicidal, but have some activity against enveloped viruses
.
Example of Biguanide and the uses
a. Chlorhexidine:
I. on skin and mucous membranes.
II. for surgical hand scrubs
III. preoperative skin preparation in patients.
IV. Coating on medical devices to prevent infection and colonisation
Why Hypochlorite ion (OCl-) cannot enter the cell freely ?
because of the –ve charge
True or false
Hypochlorite ions Don’t have Germicidal action
False
Hypochlorite disinfectants (chlorine disinfectants) Examples and uses
- NaOCl used as household disinfectant (Clorox®)
- Ca (OCl)2 used to disinfect dairy equipment
- Chlorine dioxide (ClO 2); gaseous form used for area disinfection
- Chloramines (chlore & ammonia) are used ;
a. To sanitize glassware & to treat dairy and food manufacturing equipments
b. For treatment of water –will kill aquarium fish and so must be neutralized
c. Less effective as germicide
Iodine is effective against
- bacteria
- endospores
- fungi
- some viruses
True or False
Iodine is Strong oxidizing agent and is Antiseptic and disinfectant
True