Antimicrobial Drugs Flashcards
1
Q
How Antibiotic Resistance Happens
A
- Antibiotics were discovered and first really used in the 20s
- Every decade there is resistance that has started to appear
- We have companies that want drugs to be used a lot (this is their product!), but we HAVE to limit our use of antibiotics
- note: dont use the word germs
- there is always resistant bacteria around, but we need to keep some competition present!
2
Q
Examples of how Antibiotic Resistance Spreads
A
- eating meat with antibiotic resistant bacteria
- hard to know the exact role of pets in all this but they are part of it and can get resistant bacteria from owner!
3
Q
Goal of Antibacterial Therapy
A
- not every infection needs antibiotics
- when we use them appropriately, they are to HELP the host rid of the infectious organism
- bacterial cells are different to the mammalian cell
- where as: it is hard to treat cancer cells as they are similar to the host and the drug is therefore somewhat toxic
4
Q
Antibiotic therapy is most effective when…
A
5
Q
Natural Defence Mechs of Patient
A
- If M.E. is damaged, they are very prone to building respiratory tract infections
- UTIs can occur for people with renal issues
6
Q
Bacterial Resistance and Antibacterial Agents
A
- bacterial resistance existed well before antibiotics were invented!
7
Q
Bacterial resistance
A
- Bacteria have been killing eachother with “antibiotics” for ages to kill other bacteria!
- A good amount of the antibiotics come from fungi (e.g. penicillin)
8
Q
Resistance and Antibiotic selection
A
- resistance does not just emerge at the site of infection but the normal flora in the gut and the skin
9
Q
The Gut Microbe- What does it do and why do we care?
A
- what happens if the gut/skin microbiome are altered by antibiotics
- both (esp. gut) is very important for the immune system and body function
- basically signals to the immune system what is ok to have in body and what isnt
10
Q
Immune system and cohabiting microbiota
A
11
Q
A
- Dysbiosis= when microbiome of the gut/skin become disordered and arent at the amount they should be
- loss of control by the gut and immune system
- often a mix of all these
12
Q
Bigger Picture: increased prevelance in people
A
- Increasing in prevelance despite the fact of knowing more and more about these diseases
13
Q
People with Immune Mediated Diseases
A
- Diseases we didnt think were immune mediated did start as immune mediated in many cases
- start with a different microbiota
- meaning antibiotics can have an effect in these situations
14
Q
Antibiotics and the microbiome
A
15
Q
Whether an antibiotic is used appropriately or not…
A
- we will cause resistance either way
- is the benefit going to outweigh the fact that you are going to change the microbiota
- use of antibiotics in the early stages of life seem to have the largest impact on the immune system and functionality of animal/human
16
Q
Responsibility of Veterinarian
A
- antibiotics dont cause many side effects as they are aimed at bacterial cells, not mammalian cells (different to anti-cancer drugs, NSAIDS)
- Vets have used lightly before as there arent really any side effects to mammalian cells
- disease prevention: worming suggestions, diet, etc.
- conservatively: treat with the right dose at the right time only when needed!
17
Q
Issues for food animals
A
18
Q
Horses
A
- MUST be signed out or it has to be treated as a food animal
19
Q
Food animals and Drug Residues
A
- Drugs have a calculated withdrawal time: time where drug administration has stopped and when the animal is able to be slaughtered
- REALLY try to avoid the use of antibiotics in food animals, or be very strict about it!
- even the smallest bit of antibiotics (ex: penicillin) can cause an allergic reaction in people who consume products
20
Q
Food Animals and Withdrawal times
A
- times are stated for all registered drugs
- the criteria MUST be followed for that withdrawal period to work
- If you are giving antibiotics for an animal destined for slaughter and production, you MUST look at data sheet
21
Q
If not licensed: The Cascade
A
- There are a lot of times where the drugs may not be licensed for a certain condition or species
- you as a vet need to make a risk based clinical judgement: happens all the time!
- need to get owner consent
- for food animals: need to have an MRL and need to be able to specify the MINIMUM withdrawal time
- also keep records of treatment
22
Q
If not licensed in food animals?
A
- these withdrawal periods are set by LAW
- use in food animals still applies the needed use of antibiotics in general, but the added layer of withdrawal times
23
Q
Gram Staining
A
24
Q
Microbial Spectrum
A
- 4 quadrants
- gram (-) aerobe: like E.Coli
- Penicillinase producing staph is really important!
25
Q
A
- gram + aerobic bacteria - STREP
26
Q
A
- Gram Negative aerobic bacteria
27
Q
A
- Staph aureus
28
Q
Atypical Bacteria Species
(6)
A
- they don’t gram stain!
enormously important as a causes of a variety of diseases depend on which area you are practicing in
29
Q
Antimicrobial classes: Inhibition of Cell Wall Synthesis
(3)
A
- knowing the mech of action doesnt reallyyy change how much we use them, but it is important in our clinical reasoning
- bacitracin: in ear drops
30
Q
Antimicrobial Classes: Inhibition of Cell Membrane Function
(4)
A
- most of these are anti-fungal drugs and not antibiotics!
31
Q
Classes: Inhibition of Protein Synthesis
(5)
A
- chloramphenicol
- macrolides
- lincosamides
- tetracyclines -commonly used
- aminoglycosides
- these do have the capacity to change mammalian protein synthesis but much lower affinity for mammalian cells!
32
Q
Classes: Inhibition of Nucleic Acid Synthesis
(5)
A
- chunking them doesnt matter a lot of the time, but helps to put them into groups to remember them!
33
Q
When to use antimicrobials?
A
- only when you definitely diagnose a bacterial infection that needs treatment
- would cause critical illness and would progress if we do not treat it
34
Q
Key Q’s and Clues: bacterial infection
A
- what are you looking for in clues? - signs of bacterial infection!
- increased body temp can ALSO occur in situations of cancer, or other illnesses (not a hard fast sign)
- neutrophil increase can happen in non-bacterial inflammation, stress, cancer
35
Q
Antibiotics not indicated for….
A
- vomiting/no diarrhea: likely do not have a bacterial disease even if they ingested most disgusting items
- urine in cats is very hostile to bacteria (echo) - often environmental/stress. OVER ten years, urine becomes more dilute and then they are more prone to bacterial infections
- huge misconception: blood in feces needs antibiotics. not necessarily a bacterial infection causing blood to be in feces
- peridontal disease: commonly given AB’s before, during, after–> mechanically clean teeth!! don’t use the AB’s- biofilms
36
Q
Choosing the right antibacterial drug
A
- can use guidelines, but you need to understand why those drugs are appropriate
- prescribe based on what is the most likely bacteria you are going to run into in the area of issue
- culture and sensitivity? is it recurrent?
37
Q
Key Questions to Ask
(8)
A
*
38
Q
A
39
Q
Factors Affecting the Success of Antibacterial Therapy
A
40
Q
Where do infections come from?
A
- A lot of the time the bacteria comes from within and gets to a place where it shouldnt be or they are in same area but the is not enough restriction placed by the body–> become a pathogen
41
Q
Infection based on location
A
- gram (-) aerobes and anaerobes in large bowel?
- liver: coming from up the biliary tract or systemically (which would be staph)
42
Q
What groups of bacteria live in the gut?
A
43
Q
What Bacteria live on the skin?
A
44
Q
Examples of gram (-) bacteria that cause disease in animals
A
48
Q
Bacterial Susceptibility
A
- Strep is dumb - hasnt developed much
- gram negatives can be very unpredictable on the other hand in their sensitivity patterns
49
Q
MIC
A
- helps us determine sensitivity pattern
- lowest effective dose!
- Drug brands have to name the bacteria that show sensitivity to that drug
- also need to be aware which slow growth and which kill
- issues: really only applies in lab settings and is inconsistent
50
Q
Bacteriostatic vs bactericidal?
A
- can really tell if bacteriacidal is better than bacteriostatic drugs: especially in terms of gram (+) infections
51
Q
Bacteriostatic Drugs
A
- For these drugs to be clinically effective, the drug concentration needs to be above the MIC for the duration of treatment or else the bacterial population will continue to grow
- need to stress the importance of timing of these doses!
52
Q
Bacteriostatic
(5)
A
- These are what they are broadly
53
Q
Bactericidal
A
- don’t need ideal conditions?
- Good if we are concerned that these animals are immunocompromised or the infection is at a specific site
54
Q
Bactericidal
(6)
A
- when all is working well, they are bactericidal
55
Q
Bactericidal Killing
A
- How do these drugs kill the bacteria?
- can be done in a time dependent manner or dose (concentration) dependent manner
56
Q
Time Dependent
A
- want that drug to be above the MIC throughout the dosing period
- 3 bactericidals by time dependent killing mechanisms
- cant give with a drug that slows down growth because they are only effective against a growing population of bacteria!
- Can’t give one dose as the concentration decreases too much before the end of the 24hr period - thus we want to give this dose twice in 12 hour periods! (graph)
- Don’t say give twice a day –> need to say EVERY 12 hours
57
Q
Concentration Dependent
A
- determined by the peak concentration achieved- can combine with bacteriostatic drugs!
- don’t depend on bacteria growing
- needs to be 8-10 times more than the MIC to be effective
- doesn’t matter that it is gone before 24 hours, but main thing is that their effec tis through concentration!
- Hamsters/rabbits: tend to give it twice a day in really small animals as they have very high metabolisms and time of action is much faster
58
Q
Red Antibacterial Activity
A
59
Q
Spectrum - Red Drugs
A
- all the dots represent bacteria
- if they are mostly in red as you are talking about a drug, wont be affective against those bacteria species
- REMEMBER THIS MOST OF ALL
- Fluoroquinolones and aminoglycosides have no effect against obligate anaerobes
- Penicillin/aminopenicillins don’t work against pen. producing staph and metranidazole does not work in anaerobic conditions? (echo)
60
Q
Green and Blue Antibacterial
A
- Once they have had multiple courses of antibiotics, this won’t work as the pattern of resistance has changed
61
Q
Spectrum- Green Drugs
A
- The more that a drug is used, the more you will see red dots appear
62
Q
Brown Antibacterials
A
63
Q
Brown Drugs
A
- there is a mixture
- don’t memorize
- but they are not red/not green
64
Q
Brown Drugs and the Empirical Choice
A
- don’t use if you aren’tsure what the bacterial infection is!!
66
Q
Atypical Bacteria
A
67
Q
What if I know the likely bacterial species causing the infection?
A
- Bordatella becoming an issue because so many dogs are getting treated by AB’s
69
Q
Pharmacokinetic Factors
A
70
Q
Difficult to Access Areas
A
71
Q
Intracellular bacteria
A
- need to be lipid soluble to get in the cell!!
72
Q
How well do they penetrate?
A
- good= good enough at passing the membrane
- Great= VERY LIPID SOLUBLE
- If we are choosing to treat a brain infection, bronchiole infection, iron infection systemically –> needs to come from blues and greens!
73
Q
Environmental Conditions
A
- What has happened at the site of infection to prevent a drug from working properly
- need to drain an abcess before giving AB
- foreign material : stone, devitalized part of bone, splinter
74
Q
Foreign Material (pharmacodynamics)
A
- body has to fight two battles
75
Q
Effects of Env’t Conditions
A
77
Q
Post Operative Infection Risk
A
- health of the tissue involves the effect of the surgery itself as well
- there is a gradation of asepsis
78
Q
When should I use perioperative antibiotics?
A
79
Q
Justification for surgical prophylaxis
A
80
Q
Post Op Risk: Surgeon and Implants
A
82
Q
Post Operative Infection risk factors
A
- patients are shocked/emaciated have a higher risk
83
Q
Post Op Infection risk: Anaesthesia and propofol
A
84
Q
Post Op Infection Risk Factors: clipping, etc
A
- Just can’t clip as well when you they are awake
- Abnormal skin will lead to staph possibly populating and invading the area
85
Q
- Indications for Surgical Prophylaxis
A
- In places where the aseptic technique is not as great, it is BETTER and CHEAPER to fix the aseptic technique before just giving them ABs
- dentals? - (diseases where they are more at risk to develop infection after dental) –> hypoadrenocorticism patients maybe, mitral valve disease
- patients with a low WBC
- ortho procedures usually get pre and then repeated if it goes longer than 90 min (surgery time) and after? - consequences would be disastrous
86
Q
Timing of Surgical Prophylaxis
A
- depending on what drug is given, you ideally give it at the time of induction as there is no delay
- if it is given SQ or IM then it can take about 1-2 hours to take effect
- Has to be present in the wound at the time of contamination!
87
Q
Best Drug for Surgical Prophylaxis?
A
- 2nd gen cephalosporin- not licensed vet med, owner will have to give consent, but it has a lot of benefits
- formulaitons may be different in different regions of the world - need to adapt
- IV induction IF possible (can take an hour and half for amoxycillin caluvulanate to reach therapeutic level)
88
Q
Surgical continuation therapy
A
- supposed to act like a security guard checking for any intruders, but don’t continue giving afterwards
- We are treating an infection, we are preventing the infection from occurring
91
Q
Major Factors influencing postop infection risk:
A
92
Q
Where would these pathogens be coming from?
(surgical Prophylaxis)
A
Skin is a big one! (surgeon and animal!)
- also depends on what surgery it is
- need to think about the likely contaminating pathogens
93
Q
What is the most useless drug to use for surgical prophylaxis in most SA cases?
A
- Amoxycillin (at least in 70% of cases- penicillinase producing)
- It is no good against staph!
- staph is one of the main concerns of surgical prophylaxis
- never use penicillin G in a SA practice
- clamoxyl is even worse - in addition will not be in the wound at the time needed
94
Q
Which are the best?
A
- Def want something that can treat Staph
- FLuoroquinolones are really good against gram negative and can be very potent around humans- try not to use!
95
Q
Questions that need to be answered in order to use ABs
A
- quinolones are the most abuse in vet med!
96
Q
Do we use Antibiotics?
A
- Pierre was given amoxicillin but it reoccured
- need to think about staph infection, gram (-)
- he is intact: need to think about prostate - need to think about drugs that can penetrate this
- could be stones since it is recurrent meaning that it could be an uncomplicated urinary infection
- amoxycillin cannot penetrate the prostate, therefore was a bit better but it returned
97
Q
questions we need to think about when prescribing AB’s
A
