Antimicrobial Chemotherapy Flashcards
Bactericidal?
Antimicrobial which kills bacteria
Bacteriostatic?
Antimicrobial which inhibits growth of bacteria.
When is a microorganism considered sensitive?
If it is inhibited or killed by an antimicrobial.
When is a microorganism considered resistent?
If it is not killed or inhibited by an antimicrobial.
MIC?
Minimal Inhibitory Concentration
What is MIC?
Minimum concentration of antimicrobial needed to inhibit visible growth of a given organism.
MBC?
Minimal bactericidal concentration
What is MBC?
Minimum concentration of the antimicrobial needed to kill a given organism
What is meant by a topical administration?
Medicine applied to the surface, like skin
What is meant by systemic administration?
Medicine taken internally, either orally or parentally.
What is meant by parental administration?
Given IV or IM
What are the three types of antibiotic inhibition?
- Inhibition of cell wall synthesis
- Inhibition of nucleic acid synthesis
- Inhibition of protein synthesis
Which type of synthesis inhibition does not affect humans?
Inhibition of cell wall synthesis because human’s don’t have cell walls
Name two types of drug which inhibit cell wall synthesis.
Penicillin
Cephalosporins
What type of drug are cephalosporins and penicillin?
Beta lactams
What specifically in the cell walls do beta lactams target?
Peptidoglycan in the cell wall
Name the types of drug which inhibit a different section of cell wall synthesis.
Glycopeptides
Name two glycopeptides.
Vancomycin and teicoplanin
Which type of bacteria do glycopeptides work against?
Only work on gram positive organisms.
What is a common issue w Vancomycin?
Risks of toxicity
What is the mechanism of action for aminoglycosides?
Inhibits protein synthesis
Which type of organism can aminoglycosides affect most efficiently?
Gram negative
Name one aminoglycoside.
Gentamicin
Describe the pros and cons of using Gentamicin.
Pros- cheap, widely use
Cons- toxicity so requires close monitoring
Give two other groups of drugs which can act on protein synthesis.
Macrolides
Tetracyclines
Give some examples of macrolides.
Erythromycin
Clarithromycin
Which organisms are usually affected by macrolides?
Gram positive organisms
Which drug is a useful alternative to penicillin?
Macrolides, like erythromycin and clarithromycin
Oxazolidinones also inhibit protein synthesis.
They are a newer drug.
Give an example of one.
Linezolid
Name two drugs which can inhibit the purine stages of DNA synthesis.
Trimethoprim and sulphamethoxazole
The combination of which two drugs gives us co-trimoxazole?
Trimethoprim and sulphamethoxazole
Which group of drugs can inhibit the process of DNA synthesis more generally?
Fluoroquinolones
Give an example of a commonly used fluoroquinolone.
Ciprofloxacin
Which organisms does Ciprofloxacin usually target?
Gram negative organisms
How is Ciprofloxacin taken?
Orally
What is one disadvantage to Ciprofloxacin?
Cannot be used in children
What are some of the types of antibiotic resistance?
Inherent or intrinsic resistance
Required resistance
Briefly describe what is meant by Inherent or intrinsic resistance.
Resistance to all strains of a given species.
Describe briefly what is meant by required resistance.
Resistance may be present in some strains of the species but not in others.
What are Beta Lactamases?
Bacterial enzymes which cleave the β–lactam ring of the antibiotic and thus
render it inactive
Which antibiotic are many hospital strains of straph.aureus resistant to?
Resistant to beta lactams like benzyl penicillin.
Which type of bacteria often have beta lactamases?
Gram negative bacilli
How do you combat beta lactamases?
- Introduce a second antibiotic which targets the beta lactamases.
OR - Modify the antibiotic to become resistant to the action of beta lactmases
Name drug which is beta lactamase resistant.
Flucloxacillin
What is another mechanism of microorganisms which prevents beta lactams from working?
Having altered target sites.
What are MRSA resistant to?
All penicillins and cephalosporins
What can gram negative organisms produce which makes them resistant to all Beta lactams?
ESBLs (extended spectrum β-lactamases)
In which type of organisms is vancomycin resistance unusual?
Gram negative organisms.
Name some penicillin’s (which will be beta lactams :) )
Benzyl penicillin
Amoxicillin
Flucloxacillin
Basically end in cillin
GENERAL
Describe aminoglycosides.
-Parenertal use only
-Action against gram negative
-Staphylococci are sensitive to them but streptococci are not
Name the most commonly use aminoglycoside.
Gentamicin
GENERAL
Describe glycopeptides.
-Parenteral use only
-Only action against gram positive (aerobic and anaerobic)
GENERAL
Describe macrolides.
-Action mainly against gram positive
-Alternative to penicillin
Name to agents used in the treatment of a UTI.
Nalidixic acid
Nitrofurantoin
Which drug would you give for the treatment of a gram negative UTI?
Nalidixic acid
or
Nitrofurantoin
Which drug would you give for the treatment of a gram positive UTI?
Nitrofurantoin
Which antibody initiates anaphylaxis?
IgE
Which infection can be a side effect of antibiotic usage?
C.difficile
What is C.difficile treated with?
Oral metronidazole or oral vancomycin
List some parts of the body which can be affected by toxicity due to broad spectrum antibiotics.
Liver
GI
Kidneys
Blood
Discuss which yeast related condition can occur due to broad spectrum antibiotics.
Thrush
Name the yeast responsible for thrush.
Candida albicans
Why is it important to consider those with renal dysfunction before administrating antibiotics?
Kidneys excrete antibiotics.
If kidneys aren’t working, accumulation of antibiotic will build up, causing toxicity
Why is it important to consider those with liver dysfunction before administrating antibiotics?
Antibiotics may be metabolised and excreted via bile so reduced function could impair this
Why do some antibiotics need to be avoided in pregnancy?
- Can increase mutation risks in baby
- Can increase risks of congenital issues
What is prophylaxis?
Administration of antimicrobials to prevent the future occurrence of infection
When may prophylaxis be given?
If a patient has been in contact with highly communicable diseases.
If a patient is going to undergo operation.
Give an example of an operation type in which prophylaxis will be given before?
Most abdominal operations
When may a combination treatment be administrated?
- To cover mixed infection by more than one organism.
- Because two antimicrobials sometimes have an enhanced effect together
- To minimise the development of resistant strains to any one agent
In which diseases is combo therapy important?
Treatment in HIV or TB
Define synergistic.
Combo of two drugs has a greater effect than their individual effects
Name one test which can measure MIC.
E test
What do polyenes bind to?
Ergosterol
Which cells is ergosterol present in?
Yeast cells
Which drug is used intra-venously for serious yeast and other fungal infections?
Amphotericin B i
What is one negative factor about Amphotericin B?
It’s toxic
What can be given orally for serious fungal infection?
Nystatin
Name an azole which used widely in the treatment of yeast infections.
Fluconazole
Which drug is used for fungal infection on skin or nails?
Terbinafine
Which type of drug is used for serious Candida and Aspergillus infections?
Echinocandins
Antiviral drugs are less common.
Name one antiviral drug which is active against Herpes Simple Virus and Varicella Zoster Virus.
Aciclovir
