Antibiotics Flashcards
(147 cards)
1
Q
Name the beta lactams
A
Penicillins, cephalosporins, monobactams, carbapenems
2
Q
Penicillins, cephalosporins, monobactams, and carbapenems are what type of agents
A
Beta lactams
3
Q
What is the mechanism of B lactams
A
irreversibly inhibit peptidoglycan polymers in cell wall to cause them to burst, inhibit penicillin binding proteins whch are enzymes that form cross links in membranes
4
Q
Are beta lactams time or concentration dependent
A
Time
5
Q
What type of organism do beta lactams work best on
A
G+
6
Q
How are most B lactams absorbed
A
Orally then rapidly distributed to ECF
7
Q
What type of clearance do B lactams have?
A
Kidney
8
Q
Do B lactams cross the BBB
A
No (Except in inflammation)
9
Q
Are B lactams bound to plasma proteins
A
Not much
10
Q
What are the three mechanisms of resistance to beta lactams
A
- b lactamase production via mutation or insertion
- change structure of PBPs
- Chance lack of penetration thru memb pores
11
Q
What are the 5 subgroups of penicillins
A
Natural b-lactamase resistant aminopenicillins extended spectrum augmented
12
Q
What type of animals are natural penicillins mainly used in
A
Large animal (horses and intra-mammary in food animal)
13
Q
How should natural penicillins be given
A
IM - NOT ORALLY because acid-labile
14
Q
Are natural penicillins degraded by b-lactamase
A
YES!
15
Q
What concerns are there for natural penicillin use
A
Long acting can cause residues in food animals, can cause CNS signs
16
Q
What orgs do natural penicillins kill
A
G+ and G- (anaerobes only)
17
Q
What is a drawback of B-lactamase resistant penicillins?
A
Narrower spectrum - confirm sensitivity
18
Q
What is the first line of drugs for treatment in small animals
A
Aminopenicillins (amoxicillan/ampicillan)
19
Q
What are the routes of administration of Aminopenicillins
A
Oral (amoxicillan), IV/IM (ampicillan)
20
Q
What are the side effects of Aminopenicillins
A
GI flora disruption - nausea and V
21
Q
What are the three classes of penicillins which are most broad spectrum
A
aminopenicillins, extended spectrum, augmented
22
Q
What benefit exists in extended spectrum penicillins?
A
Improved Q3 (G- aer), especially pseudomonas! (IV use)
23
Q
Are extended spectrum penicillins susceptible to b-l’ase?
A
Yes
24
Q
Describe augmented penicillins
A
Combination of broad spectrum agent + b-l’ase inhibitor
25
What is the toxicity for augmented penicillins
GI toxicity in horses, rabbits, hamsters and guinea pigs
26
What type of effect do penicillins have on orgs
Bacteriocidal
27
What type of antibiotic are cephalosporins
B-lactam
28
What is the mechanism of action of cephalosporins
bacteriocidal cell wall inhibitors via PBP
29
Are cephalosporins time or conc dependent
Time
30
What is the form of excretion for cephalosporins
Renal
31
What cautions exist for cephalosporins
Can be cross reactive in penicillin sensitive animals
32
Are cephalosporins protein bound
No
33
Describe cephalosporin generations
Go in sequence of oldest to youngest, newer have better gram negative coverage and better resistance to b-l'ase
34
What spectrum do 1st generation cephalosporins cover
Q1 and Q2, some Q3
35
What type of drug is cefazolin
First generation cephalosporin
36
What kind of drug is cephalexin
1-cephalosporin
37
What is the first line of use cephalosporin in SA
1-gen
38
What spectrum do 2nd generation cephalosporins cover
Same as 1-gen but with greater Q3
39
Do 2-cephalosporins cover pseudomonas?
No
40
Do 1-cephalosporins cover pseudomonas?
No
41
What spectrum do 3rd generation cephalosporins cover
Q1 and 2 with better gram negative than 2-gen
42
What kind of antibiotic is cefpodoxime
3-cephalosporin
43
Name a 1-cephalosporin
Cephalexin, cefazolin
44
Name a 2-cephalosporin
Cephoxitin, cefotetan
45
Name a 3-cephalosporin
ceftiofur, cefpodoxime
46
What species is cephalexin approved in
Dogs only
47
What Rx should treat bacterial pyoderma
cephalexin (1-cephalosporin_
48
What method of admin should be used for 3-cephalosporins
parenteral depending on species
49
Restrictions on 1-gen cephalosporins
Food animals now may use- major use must follow route/dose/freq restrictions (no ELDU), minor ok to use
50
What are the toxicities of cephalosporins
Cross hypersensitivity with penicillins, GI upset (give with meal), chronic use causing overgrowth of candida/pseudomonas
51
What kind of agent is Imipenem?
Beta lactam from carbapenem class
52
What spectrum does Imipenem have
anaerobes and gram + aerobes
53
What mechanism of action does bacitracin have
Cell wall inhibitor by inhibiting phosphorylation (like vancomycin)
54
What organisms are killed by bacitracin
G+
55
What mechanism of action does vancomycin have
Cell wall inhibitor by inhibiting phosphorylation (like bacitracin)
56
What is the method of administration for vancomycin
IV (po for GI issues)
57
How is vancomycin excreted
Renally
58
What are the toxicities of vancomycin
Ototoxic, nephrotoxic, tissue irritant
59
What are the restritions on vancomycin?
NO food animal use, last resort for MRSA in dogs
60
What mech of action does polymixin have
Cell wall inhibitor via detergent like action
61
What kind of organisms are killed by polymixin
Gram neg
62
Why are penicillins used for UTI
High urine concentration due to clearance
63
What type of agents are aminoglycosides
Bacteriocidal
64
What are two examples of aminoglycosides
Amikacin and gentamycin
65
Are aminoglycosides time or conc dependent
Concentration
66
Describe aminoglycosides
Highly water soluble, positively charged at bio pH, not lipophilic, low body distribution
67
What is the mechanism of aminoglycosides
Irreversible inhibition of protein synthesis via binding to 30S subunit of ribosome which is lethal to most bacteria
68
What is the route of administration for aminoglycosides
IV/IM because not orally absorbed (used PO in gastroenteritis)
69
Where are aminoglycosides distributed
ECF- not intracellular, accumulates in renal cortex and inner ear
70
What is the elimination of aminoglycosides
renal
71
What are the toxicities for aminoglycosides
With long term use:
Nephrotoxic- necrosis of tubules
Ototoxic- can be irreversible
Neuromuscular weakness, anaphylaxis
72
Describe aminoglycoside resistance
Usually limited to a few drugs, not the whole group; enhanced enzyme degradation, decreased membrane transport, altered ribosome binding site
73
What is unique about how aminoglycosides enter organisms
Must be transported by an energy requiring transporter that requires oxygen
74
What are the contraindications of aminoglycosides
renal disease, pregnant, fever, myasthenia gravis, neuromuscular disorders
75
What are pseudomonas most susceptible to?
Quinolones and aminoglycocides
76
What kind of organisms are most sensitive to aminoglycosides
```
Gram negatives (esp. aerobic like pseudomonas)
(a few G+ orgs- staph!)
```
77
What drug are aminoglycosides synergistic with
B-lactams
78
What kind of drug is gentamycin
aminoglycocide
79
What kind of drug is amikacin
Aminoglycocide
80
What kind of effect do tetracyclines have
Bacteriostatic
81
What is the mechanism of tetracyclines
reversible inhibition of protein synthesis by 30S ribosome
82
How do tetracyclines enter an organism
Transporter via active transport (determines spectrum of activity)
83
Are tetracyclines acid or base?
Amphoteric- both acid and base
84
Name an amphoteric abx
tetracyclines
85
How are tetracyclines subclassified?
Duration of action
86
What makes a tetracyclines short or fast acting
Short: H20 soluble
Long: lipid soluble
87
Name two examples of tetracyclines
Doxycyclin, oxytetracyclin
88
What kind of organisms are killed by tetracyclines
Gram +, GrNeg Anaer, mycoplasmas, rickettsials and spirochetes
89
What are the mechanisms of resistance for tetracyclines
ALtered bacterial transporter, active excretion via pump, enzymatic degradation
90
What abx do tetracyclines show cross resistance with
Aminoglycosides and sulfonamides
91
Are tetracyclines protein bound?
Yes- some highly
92
What is the best route of administration for tetracyclines
Oral- well absorbed - food reduces absorption
93
What is the excretion of tetracyclines? Name exceptions
Renal except doxy (hepatic
94
Describe tetracyclines' toxicity
GI, superinfections, ruminal dysfunction, photosensitizing, IM pain/swelling, IV arryhthmias, teeth/bone discoloration in young, hypersensitivity, (expired: nephrotoxic)
95
What restrictions should be used in tetracyclines
Pregnant animals; (remember drug interactions
96
Name interactions for tetracyclines
Muscle relaxants, food, antacids (oral), IV fluids, loop diuretics, toxic digoxin
97
What species cant use doxycycline
LA (use in dog/cat)
98
What species cant use oxytetracyclines
Dog/cat (use in beef and non-lactating dairy cattle)
99
What special actions mst be taken in administration of tetracyclines
Cats- must follow with water- can cause strictureI
100
What class of tetracycline is doxy
Long acting
101
What class of tetracyclines is oxytetra
intermediate acting
102
What route should doxy be given?
IM or SC
103
What is the drug of choice for erilchia
Doxy
104
Is doxy lipo or water philic/
lipo
105
What are side effects of oxytetracycline
diarrhea and shock in horses
106
Describe macrolides
highly lipid soluble (hard to get rid of), all contain a lactone ring
107
What is the mechanism of action for macrolides
Bacteriostatic - Reversible inhibition of ribosome protein synthesis in 50S
108
What kind of organisms are sensitive to macrolides
Gram +, few gram neg, intracellular orgs like rickettsials and mycoplasma
109
Do macrolides cross BBB
No
110
Elimination of macrolides
liver, biliary
111
What are the toxic effects of macrolides
Major GI,
112
What restrictions should be used in macrolides
Caution of colitis and D in horses, guinea pigs, rabbits. Rectal swelling in sheep
113
Describe the resistance of macrolides
Alteration of ribosome binding sites
114
What are the drug interactions for macrolides
May precipitate and decrease efficacy by binding with many drugs, prolongs effect of warfarin, elevates digoxin levels in dogs
115
What kind of drug is clindamycin
Macrolide
116
What kind of drug is azithromycin
Macrolide
117
What kind of drug is tylosin
Macrolide
118
What is an advantage of azithromycin
Less GI effects
119
What drug is best for toxoplasma and resistant R. equi
Macrolides
120
Describe the resistance to chloramphenicol
Readily transmitted plasmid
121
What is the MOA of chloramphenicol
Reversible inhibition of 50S protein synthesis
122
Does chloramphenicol cross the BBB
Yes
123
What is the elimination of chloramphenicol
Hepatic
124
Toxicitiy- chloramphenicol
Human toxicity- major concern
GI disturbances esp. cats
Reduced liver metabolism and diminished clearance
Irreversible bone marrow suppression (aplastic anemia) in humans and dogs
125
Restrictions- chloramphenicol
NO food animals
126
What is florfenicol
Synthetic derivative of chloramphenicol that is allowed in food animals
127
How are sulfonamides classified
Water solubility, duration and tissue distribution
128
What are the side effects of sulfonamides
keratoconjunctivitis sicca, IMHA, renal crystallization
129
What is the MOA of sulfonamides
Interference with folic acid synthesis in DNA synthesis
130
Sulfonamides- bacterio-
static at ther. levels
131
What orgs killed by sulfonamides
Gram neg and pos, not good in anaerobes nor pseudomonas
132
What two drugs are not good treating abscesses
Sulfonamides and aminoglycocides
133
Describe resistance in sulfonamides
High cross resistance, diverse mechanisms
134
Elimination- sulfonamides
kidney and liver
135
What are the drug interactions of sulfonamides
Disrupted protein binding and renal tubular secretion with many drugs, antagonized by PABA, oral antacids reduce absorption
136
What is the newest group of antibiotics
Fluoroquinolones
137
What kind of drugs are similar to fluoroquinolones
Weak organic acids- penicillins, cephalosporins, sulfas
138
Time or conc- Fluoroquinolones
Concentration
139
MOA- Fluoroquinolones
Inhibit bacterial DNA gyrase (topoisomerase II) to block DNA transcription
140
What drugs are good for respiratory tract?
Fluoroquinolones
141
What is the spectrum for Fluoroquinolones
Broad Gram neg and aerobes
142
QRDR
Quinolone resistance determining region-
143
What is the excretion of Fluoroquinolones
Hepatic and renal
144
Better FQ in dogs
Marbofloxacin - higher AUC and Cmax
145
What are teh side effects of FQs
Mild! Gi, nephro if dehydrated
146
What are the contraindications of FQs
Pregnany, young (damage to growth plates), retinopathy in cats, off label in food animal
147
What are the main interactions of FQs
Antacids, food, sucralfate, NSAIDs (Seizure)
