Lecture 17 Flashcards
What are azols used for?
Anti-fungal
What is the mode of action for azols?
Disruption of the phosolipoprotien membrane
What are the two major types of azols?
- Imidazoles
2. Triazoles
Name the triazols
Fluconazol (difucan)
Voriconazole
Name the imidazoles
Clotrimazole
Miconazole
Ketoconazole
What is the mode of action for clotrimazole?
Disruption of the phosolipoprotien membrane
What is clotrimazole used for?
Systemic mycoses
Although clotrimazole is unable to penetrate the blood brain barrier, why have newer drugs been chosen over it?
It is more toxic than modern day alternatives
What is the mode of action for miconazole?
Disruption of the phosolipoprotien membrane
Miconazole is used for what disease?
Candiasis when it is superficial (vulvovaginitis)
Ketoconazole works with what kind of mode of action?
Disruption of the phosolipoprotien membrane
In what form are clotrimazole, miconazole and ketoconazole normally found in?
A topical cream
Ketoconazole is used to treat what?
Cadiasis when it is superfical (vulvovaginitis)
All three imidazoles can be used to treat what infection?
Mild infections of ringworm or athlete’s foot (caused by microsporum, trichophyton, and epidermophyton)
Fluconazol is also called what?
Diflucon
What is the mode of action for fluconazol?
Disruption of the phosolipoprotien membrane
What is fluconazol used to treat?
Yeast infections, not really molds
Voriconazole is a DOC for what?
Systemic mycoses
What drug is able to penetrate the blood brain barrier, making it effective against aspersillosis?
Voriconazole
What organism produces polyene antibiotics? Where is this organism found?
streptomyces which is found in the soil
What is the mode of action of polyene antibiotics?
attacks the cell membrane by binding with sterols
What organisms do polyene antibiotics effect?
us and fungi
they do not work against bacteria as they don’t have sterols in their membrane
Name the sterol in human cell membranes
cholesterol
name the sterol in fungi cell membranes
ergosterol
Are polyene antibiotics cidal, inhibitory, static, or ineffective against their intended target?
cidal
Name the 2 types of polyene antibiotics
nystatin and amphotericin B
What is Nystatin a DOC for? what is it an alternate for?
It is not a DOC or an alternate for anything
What is Nystatin commonly used against?
dermatophyte yeast infections (superficial on the skin’s surface)
What does Candida albicans cause?
dermatophyte yeast infections (superfical) oropharyngeal candidiasis (thrush) vulvovaginal candidiasis (genital yeast infection)
What forms does nystatin come in?
creams, lozenges, and oral rinses
What is anphotericin B a DOC for? an alternate for? What else is it given for?
Is a DOC for systemic mycosis
not an alternate for anything
also given for severe candidiasis
What is systemic mycosis and what causes it?
a fungal infection that attacks the inside of the body in the organ systems
caused by aspergillosis
What is aspergillosis? Who gets it?
a dimorphic fungi that looks like mold at 25 degrees C and looks like yeast at 37 degrees
Genetics and immune system strength determine if you are susceptible to it
how is amphotericin B given?
IV
List off the chemical methods which disrupt the lipoprotein membrane
detergents
polymyxins
polyene antibiotics
Azoles
What are surfactants and what do they do?
they are molecules with similar solubility to the chemicals in the cell membrane (polar head and non polar tail, amphipathic)
they insert themselves into the cell membrane, disrupting it
they are cidal but non selective
What does amphipathic mean?
having a polar end and a non polar end
for example:
surfactants are amphipathic as are lipoprotiens which make up cell membranes
What happens to the cell membrane when exposed to low concentrations of surfactants? to high concentrations of surfactants?
at low concentration- distort the membrane
at high concentration- dissolve the cell membrane by poking holes in it
Name the types of Detergents
cationic detergents
anionic detergents
nonionic detergents
What is the mode of action of detergents? Are they selective? Are they cidal?
disrupt the lipoprotein membrane
They are non selective (damage bacteria, fungi and us depending on the drug)
They are cidal
Which of the detergents is most active?
cationic detergents
Which of the detergents is mildly active?
anionic detergents
Which of the detergents has no activity?
nonionic detergents
Name some examples of cationic detergents
benzal alkonium chloride
benzal ammonium chloride
cetyl-pyridinium chloride
What are cationic detergents good against? What aren’t they good against
Good against:
G+ bacteria
Bad against: G- bacteria (b/c of outer membrane) TB Hepatitis B spores
How is the toxicity of cationic detergents?
low toxicity, can be used in food industry and hospitals (against staph and strep)
What are anionic detergents good against?
organism which are sensitive such as: meningococcus syphilis streptococcus pneumonia gonorrhea (gonococcous)
What are some examples of anionic detergents?
sodium lauryl sulfate
bile salts such as McConkey’s agar and Taxo P discs
What is McConkey’s agar used for?
to kill the G+ bacteria and allow only G- to grow out
Name an example of nonionic detergents
bland soap
What is the mode of action of polymyxins?
disruption of the lipoprotein membrane
Are polymyxins cidal? are they selective?
they are cidal
they are nonselective (affect anything with a lipoprotein membrane)
What produces polymyxins?
soil bacteria, specifically the bacillus species
Are detergents ampipathic?
yes
Are polymyxins ampipathic?
yes
What are the most frequently used polymyxins?
polymyxins B and E aka colistin
Describe polymycin B including spectrum, toxicity, form commonly found in (cream, tablet, iv, etc), what bacteria it is used on
Polymyxin B: narrow spectrum very toxic (not a DOC) used against resistant bacteria such as acinetobacter is used topically
What are acinetobacter? What Do they cause? Give an example
G- rods non fermenters normally cause nosocomical infections very resistant to antibiotics can cause pneumonia and meningitis and example is pseudomonus pasogenus
What is an OTIC infection? what can be used to treat it?
otitis externa- outer ear infection
can be treated with polymyxin B topically
What kinds of infections can be trated with polymyxin B topically?
OTIC
Opthalic infections
skin infections (found in triple antibiotic creams)
What is kirby bauer? describe it
what are the break points?
a disc diffusion technique
can test multiple antibiotics at one time
the break points are the zone of inhibition
Drugs are classified as R(esistant), S(ensitive), or I(ntermediate)
Qualitative data
What is MIC? describe it
what are the break points?
minimum inhibitory concentration- tube dilution technique
can only test one antibiotic at a time
have different dillutions of the antibiotic across the tubes
The break point is the tube with the lowest concentration that does not grow bacteria; optimal therapy for blood concentration
What is the MIC for ampicillin and E. Coli?
4 micrograms per millileter
What are some delivery methods to achieve optimal therapy?
oral drugs
IM (intra muscular)
IV (intra venus)
What is the MBC? how is it determined?
Minimum bacteriacidal concentration
Take the MIC tubes that didn’t grow bacteria and make agar plates. The lowest concentration tube that doesn’t grow bacteria is the MBC (killed them instead of inhibiting growth)
What is the E-test? how does it compare to other methods such as MIC and kirby bauer?
diffusion technique, gives MIC without doing serial dilutions
strip of varying concentrations of an antibiotic
very expensive
not as accurate as serial dilutions, can’t give MBC
What is DOC? who publishes it?
drug of choice- most active drug against and organism which causes the least amount of harm
published by the medical letter
What is polymyxin E used for?
treatment of otitis exterma
What are the antibiotics in thayer martin selective agar?
vancomycin to kill G+
Colistin (a combination of polymyxin B and E) to kill G-
Nystatin to inhibit yeast
Name a dimorphic fungi
Aspergillosis
