Antimicrobials Flashcards
What are the four quadrants for the antimicrobial spectrum?
Gram positive aerobes - Gram negative aerobes - Obligate anaerobes - Penicillinase producing Staph
Are there bacteria which don’t fit into the four quadrant spectrum? What are they called?
Yes - Atypical bacterial species
Give an example of some Atypical bacteria
Rickettsia - Mycoplasma - Chlamydia - Borrelia - Bartonella - Mycobacterium
Outline a responsible way to use antimicrobials
Think Global - Act Local
When should antibacterials be used?
Definite diagnosis - Likely diagnosis when everything taken into account - Disease will progress without medical intervention - If animal in critical condition
What clues can tell you if it is a bacterial infection or not?
Heat, redness or swelling?
Pyrexia?
Neutrophillia?
What three cases especially are very unlikely to be a bacterial infection?
Vomiting without diarrhoea - Haematuria in cat <10 - Blood in faeces
What are the most likely bacterial infections of the mouth?
Gram negative and anaerobic from GIT
What are the most likely bacterial infections of the respiratory system?
In bronchi - bordatella
Pneumonia - could be anything
What are the most likely bacterial infections of the skin?
Staphlococcus
What are the most likely bacterial infections of the urinary tract?
Gram negative from urethra - Possibly Staph
What are the most likely bacterial infections of the liver?
Gram negative from bile duct
What are the most likely bacterial infections of cat wounds?
Mycobacterium
In general, if bacteria are not ______ to a drug in vitro they will be resistant __ ____
Susceptible - In vivo
What does MIC stand for? What does it mean?
Minimum inhibitory concentration - Lowest concentration of drug that will inhibit bacterial growth
What is usually used to determine therapeutic dose?
MIC90
What antimicrobials inhibit cell wall synthesis?
Penecillin - Cephalosporins - Bacitracin
What antimicrobials inhibit cell membrane function?
Polymyxins - Amphotercin - Imidazoles - Nystatin
What antimicrobials inhibit protein synthesis in the nucleus?
Chloramphenicol - Macrolides - Lincosamides
What antimicrobials inhibit protein synthesis?
Tetracyclines - Aminoglycosides
What antimicrobials inhibit nucleic acid synthesis?
Sulphonamides - Trimethoprim - Quinolones - Metronidazole - Rifampin
What does Bacteriostatic and Bactericidal mean?
Bacteriostatic = inhibits growth of organisms Bactericidal = kills bacteria
For bacteriostatic drugs to be effective they have to be maintained at what level and for how long?
Over 80% of MIC - at least 50% of 24hrs
Give examples of Bacteriostatic drugs?
Chloramphenicol - Lincosamides - Macrolides - Tetracyclines - Non-potentiated Sulphonamides
Give examples of Bactericidal drugs?
Penicillins - Cephlasporins - Aminoglycosides - Fluoroquinolones - Potentiated Sulphonamides (TMPS) - Metronidazole
What are the two types of bactericides?
Concentration dependent - Time dependent
What level do concentration dependent bactericides have to stay at to be?
Eight times the MIC
What determines the therapeutic effect of concentration dependent bactericides?
The area under the concentration curve
Why can’t bacteriostatic drugs not be used in conjunction with time dependent bactericidal drugs?
Bacteria need to be multiplying for time dependent bactericidal to work
Which drugs are ineffective against gram positive aerobes?
Aminoglycosides - Metronidazole
Which drugs are ineffective against gram negative aerobes?
Metronidazole - Penicillin G - Lincosamides/Macrolides
Which drugs are ineffective against obligate anaerobes?
Fluroquinolones - Aminoglycosides
Which drugs are ineffective against Penicillinase producing Staphlococcus?
Penicillin G - Aminopenicillins - Metronidazole
What bacteria is Penicillin effective against?
Gram positive aerobes and Obligate anaerobes
What is a ‘brown’ drug? Give an example of an all quadrant brown drug
Drugs that have a moderate effect on bacteria - TMPS
Which drug has a brown effect for most of the quadrants but is excellent against atypical bacteria?
Tetracyclines
Which areas of the body are quite hard for antimicrobial drugs to access?
Brain - Eye - Prostate - Bronchus - Mammary glands
Which drugs have poor penetration of hard to reach tissues?
Penicillins - Cephalosporins - Beta lactamase inhibitors - Polymixins - Aminoglycosides
Which drugs have good penetration of hard to reach tissues?
Sulphonamides - Trimethoprim - Lincosamides - Macrolides - Tetracycline
Which drugs have a great penetration of difficult to reach tissues?
Chloramphenicol - Fluoroquinolones - Lipophillic tetracyclines - Metronidazole - Rifampin
When would surgical prophylaxis be acceptable?
High risk of infection either because of long surgery, use of implants, patient health and the disease process
When should surgical prophylaxis be administered?
Before the surgery
What is a useless surgical prophylactic? Why?
Long acting amoxycilin - takes 12 hours to reach therapeutic concentration
Which bacterial quadrants is fluoroquinolones good and bad at?
Green - Gram negative aerobes, Staph
Brown - Gram positive aerobes
Red - Obligate anaerobes
Which drugs are effective against gram positive aerobes?
Penicillin - Cephalosporins - Lincosamides - Tetracyclines - Rifampin - Fluoroquinolones
Which drugs are effective against gram negative aerobes?
Fluoroquinolones - Aminoglycosides - Cephalosporins - Amoxy-clav
Which drugs are effective against Staph?
Amoxy-clav - Cephalosprins - Cloxacillin - Fluoroquinolones - Rifampin - Clindamycin (not great)
Which drugs are effective against Obligate anaerobes?
Penicillin - Amoxy-clav - Clindamycin - Metronidazole - Cloramphenicol - Rifampin
