Antimicrobial Drugs Flashcards
(110 cards)
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
* **gram + aerobic bacteria - STREP**
26
* **Gram Negative aerobic bacteria**
27
* **Staph aureus**
28
Atypical Bacteria Species
| (6)
* they don't gram stain!
enormously important as a causes of a variety of diseases depend on which area you are practicing in
29
Antimicrobial classes: Inhibition of Cell Wall Synthesis
(3)
* 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
Antimicrobial Classes: Inhibition of Cell Membrane Function
(4)
* most of these are anti-fungal drugs and not antibiotics!
31
Classes: Inhibition of Protein Synthesis
(5)
* 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
Classes: Inhibition of Nucleic Acid Synthesis
(5)
* chunking them doesnt matter a lot of the time, but helps to put them into groups to remember them!
33
When to use antimicrobials?
* 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
Key Q's and Clues: bacterial infection
* 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
Antibiotics not indicated for....
* 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
Choosing the right antibacterial drug
* 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
Key Questions to Ask
| (8)
*
38
39
Factors Affecting the Success of Antibacterial Therapy
40
Where do infections come from?
* 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
Infection based on location
* gram (-) aerobes and anaerobes in large bowel?
* liver: coming from up the biliary tract or systemically (which would be staph)
42
What groups of bacteria live in the gut?
43
What Bacteria live on the skin?
44
Examples of gram (-) bacteria that cause disease in animals
45
Examples of anaerobic bacteria that cause disease in animals
46
Examples of gram + aerobic bacteria that cause disease in animals
47
Examples of atypical bacteria that cause disease in animals
48
Bacterial Susceptibility
* Strep is dumb - hasnt developed much
* gram negatives can be very unpredictable on the other hand in their sensitivity patterns
49
MIC
* 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
Bacteriostatic vs bactericidal?
* can really tell if bacteriacidal is better than bacteriostatic drugs: especially in terms of gram (+) infections
51
Bacteriostatic Drugs
* 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
Bacteriostatic
| (5)
* These are what they are **broadly**
53
Bactericidal
* don't need ideal conditions?
* Good if we are concerned that these animals are immunocompromised or the infection is at a specific site
54
Bactericidal
| (6)
* when all is working well, they are bactericidal
55
Bactericidal Killing
* How do these drugs kill the bacteria?
* can be done in a **time dependent manner or dose (concentration) dependent manner**
56
Time Dependent
* 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
Concentration Dependent
* 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
Red Antibacterial Activity
59
Spectrum - Red Drugs
* 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
Green and Blue Antibacterial
* Once they have had multiple courses of antibiotics, this won't work as the pattern of resistance has changed
61
Spectrum- Green Drugs
* The more that a drug is used, the more you will see red dots appear
62
Brown Antibacterials
63
Brown Drugs
* there is a mixture
* don't memorize
* but they are not red/not green
64
Brown Drugs and the Empirical Choice
* don't use if you aren'tsure what the bacterial infection is!!
65
Structure of the microbiota community can be influenced by...
(4)
* genetics
* diet (supersize me)
* infection
* antibiotics - **which we have control over!**
66
Atypical Bacteria
67
What if I know the likely bacterial _species_ causing the infection?
* Bordatella becoming an issue because so many dogs are getting treated by AB's
68
Factors Affecting the Success of AB therapy
(5)
* What bugs live where?
* Bacterial susceptibility
* Distribution to site of infection (pharmacokinetic phase)
* Local Conditions (pharamacodynamic phase)
* Client Compliance
69
Pharmacokinetic Factors
70
Difficult to Access Areas
71
Intracellular bacteria
* need to be lipid soluble to get in the cell!!
72
How well do they penetrate?
* 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
Environmental Conditions
* 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
Foreign Material (pharmacodynamics)
* body has to fight two battles
75
Effects of Env't Conditions
76
Surgical Prophylaxis
* Use of antimicrobials pre and post surgery to _prevent_ infection
* Need to think about what bacteria may be present in a surgical procedure
* ALSO, which surgeries require prophylaxis
77
Post Operative Infection Risk
* health of the tissue involves the effect of the surgery itself as well
* there is a gradation of asepsis
78
When should I use perioperative antibiotics?
79
Justification for surgical prophylaxis
80
Post Op Risk: Surgeon and Implants
81
Wound Classification
* **Contaminated** - e.g. penetrating abdominal cavity injury. might not yet have peritonitis, but the fact that there is a penetrating wound, infection is extremely likely
* **Dirty** - e.g. septic peritonitis. wound breakdown, ulcer into cavity, etc.
* Clean: no inflammation, GIT or Resp tract are not affected (ex: a spay)
82
Post Operative Infection risk factors
* patients are shocked/emaciated have a higher risk
83
Post Op Infection risk: Anaesthesia and propofol
84
Post Op Infection Risk Factors: clipping, etc
* Just can't clip as well when you they are awake
* Abnormal skin will lead to staph possibly populating and invading the area
85
* Indications for Surgical Prophylaxis
* 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
Timing of Surgical Prophylaxis
* 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
Best Drug for Surgical Prophylaxis?
* 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
Surgical continuation therapy
* 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
89
What are clear situations when antimicrobials are inappropriate?
*
90
Consideration if some WHO defined critically imp. antimicrobials of highest priority are really needed
* Some of the ABs that are clinically important are also important for our animals
* Only use carbapenems if necessary- ONLY if indicated as only solution
* 3rd gen cephalosporins --\> very good against nasty gram (-)s
* fluoroquinolones: really important in human health and therefore we need to be very careful when using them, we can use it, but just NEED to be careful
91
Major Factors influencing postop infection risk:
92
Where would these pathogens be coming from?
(surgical Prophylaxis)
**Skin is a big one! (surgeon and animal!)**
* also depends on what surgery it is
* need to think about the likely contaminating pathogens
93
What is the most useless drug to use for surgical prophylaxis in most SA cases?
* 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
Which are the best?
* **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
Questions that need to be answered in order to use ABs
* quinolones are the most abuse in vet med!
96
Do we use Antibiotics?
* 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
questions we need to think about when prescribing AB's
98
What Determines what Antibiotics are used?
* #1: If it is not legal, don't use it! - you can lose vet license if you use certain drugs
* Drugs behave very differently in different species (goat v. sheep v. cow... etc.)
* micro-env't: what will stop AB's from working? - **debris, fluids**
99
AB's: **Inhibition of Cell Wall Synthesis**
* Penicillins
* Cephalosporins
* Bacitracin
100
AB's: **Inhibition of cell membrane function**
* Polymyxins
* amphotericin B
* imidazoles
* **nystatin** - Nystatin is an antifungal that works by stopping the growth of fungus
101
AB's: **Inhibition of Protein Synthesis**
* Chloramphenicol
* Macrolides
* Lincosamides
* Tetracyclines
* Aminoglycosides
102
AB's: **Inhibition of NA synthesis**
* Sulphonamides
* Trimethoprim
* Quinolones
* Metronidazole
* Rifampin
103
Bacteriostatic Drugs
* Tetracyclines
* chloramphenicol & florphenicol
* non-potentiated sulphonamides
* macrolides
* lincosamides
104
Bactericidal Drugs
* aminoglycosides
* cephalosporins
* fluoroquinolones
* metronidazole
* penicillins
* potentiated sulphonamides
105
Batericidal Drugs
## Footnote
**Time Dependent Drugs**
* **should be above MIC for as long as possible** **_each day_**
* Recommened \>80% of the day
* No advantage of high Cmax
* **Correct Dose Timings are Important**
* **_BACTERIA NEED TO BE MULTIPLYING TO HAVE EFFECT-_ Do not give with Bacteriostatics**
* *penicillins, cephalosporins, TMPS (Trimethoprim/sulfamethoxazole)*
106
Bactericidal:
**Concentration Dependent Drugs**
* peak concentration achieved and/or area under plasma concentration vs. time curve predicts antibacterial success
* **higher peak plasma concentration = greater proportion of target bacteria killed & longer post-antibiotic effect**
* **_Cmax/MIC ratio_ =** predictive of success of treatment
* **optimal: achieve \> _8:1_**
* Dont need to be multiplying! - **can give with bacteriostatics**
* *aminoglycosides, fluoroquinolones, metranidazole*
107
Most common treatment for atypical bacteria
## Footnote
**(ex: Mycoplasma & Chlamydia)**
* **Tetracyclines**
* Chloramphenicol or Florphenicol
* Fluoroquinolones
* Macrolides
108
Pus inactivates...
| (pharmacodynamic phase)
TMPS
109
Low PH--\>
| (Pharmacodynamic phase)
marked loss of activity
* erythromycin
* clindamycin
* fluoroquinolones
110
What Drugs must you never use in FA species (FPA's)
**\*Some horses exempt due to Section 9 of passports**
* **Metronidazole** (carcinogenic)
* **Benzyl-penicillin** (Crystapen)
* **Metaclopramide**
* **Chloramphenicol** -\> aplastic anemia in humans after oral consumption
* **Lidocaine**
* **Gentamicin/amikacin**
* **Phenylbutazone** (--\>A. anaemia)
* **Enrofloxacin (Baytril)** - Do not use in birds producing eggs for human consumption
