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PHAR 152 Microbes and Antibiotics > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

Describe Penicillins (Strucutre, MOA, Resistance)

A

Thiazolidine ring attached to a Beta-lactam ring
Bind to PBP to inhibit peptidoglycan synthesis and activate autolytic enzymes in cell wall
Bactericidal
Resistance via beta-lactamase secretion, Lack or altered PBP, efflux of drug out of the cell, and failure to synthesize peptidoglycans (mycoplasmas or metabolically inactive bacteria
Oral Availability varies
Most excreted through kidneys
Wide tissue distribution including the CNS
Generally short half-lives
Concentration independent pharmacodynamics

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2
Q

Describe Penicillin G and its uses

A

Natural Penicillin
Highly active against Gram Positive bacteria and spirochetes
acid liable (not oral)
IM or IV
DOC for streptococci, pneumococci, meningococci, spirochetes, clostridia, anaerobic gram psotive rods, and actinomyces. Also used for enterococci

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3
Q

Describe Penicillin V and its uses

A

Natural Penicillin
Highly active against Gram Positive bacteria and spirochetes
Oral Formulation
more acid stable than Penicillin G but, needs to be taken on an empty stomach
DOC for streptococci, pneumococci, meningococci, spirochetes, clostridia, anaerobic gram psotive rods, and actinomyces. Also used for enterococci

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4
Q

Describe Isoazolyl Penicillins (name them all) and there uses

A

Mthicillin (cloxacillin, flucloxacillin, and dicoloxacillin)
Relative resistnace to beta-lactmases
IV and Oral
Less gram positive activity
Used for staphylococcal infections, specfically Staph aureus that is MSSA
NOT USED for MRSA

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5
Q

Describe Aminopenicillins (name both) and there uses

A

Activity agaisnt both gram postive and gram negative bacteria but negative spectrum is fairly limited
destroyed by beta-lactamases
Ampicillin: IV, more acid stable than natural penicillins but,poor bioavailabilty
Amoxicillin: Oral, better absorption and more acid stable, commonly combined with clavulanic acid
Amoxicillin is the only penicillin acid stable enough to take with food
Used for: Streptococci, enterococci, Neiserria sp., non-beta-lactamase producing H. influenzae, E. coli, P. mirabilis, Salmonella, and more.

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6
Q

Describe Ureidopenicillins and there uses

A

Piperacillin
Increased activity against gram negative rods
active against Pseudomonas aeruginosa
Parenteral only
Can be combined with tazobactam

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7
Q

Name some Adverse Effects of Penicillins

A

Diarrhea, upset GI, fever, nephritis, eosinophilia, serum sickness, skin rashes, anaphylactic shock
allergic reaction, seizures, electrolyte imbalances, newutropenia, thrombocytopenia

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8
Q

Describe Cephalosporins

A

7-aminocephalosporanic acid, contain beta-lactam ring
Bind to PBP to inhibit peptidoglycan synthesis and activate autolytic enzymes in cell wall
Bactericidal
Resistance: lack of PBP or altered PBP, beta-lactamase production; resistant to beta-lactamases produced by staph aureus and common gram negative bacilli, efflux, inability of drug to penetrate
Cephamycin = an O where the S is

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9
Q

Describe First Generation Cephalosporins

A

Cephalexin and Cefadroxil are Oral agents
Cefazolin is IV/IM agent
Active agianst gram postive cocci but not active agaisnt enterococci or MRSA
Active agianst some gram negative bacilli such as E. coli, Proteus, and Klebsiella
Do not penetrate CNS
Cefazolin used for surgical prophylaxis

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10
Q

Describe Second Generation Cephalosporins

A

Cefuroxime axetil and Cefprozil are oral agents
Cefuroxime is IV/IM
Cephamycin drug is cefoxitin
Active agianst gram postive cocci but not active agaisnt enterococci or MRSA
Active agianst some gram negative bacilli such as E. coli, Proteus, and Klebsiella
Greater gram negative bacilli coverage but not Pseudomonas aeruginosa
cephamycin is used in mixed aerobic/anaerobic infections

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11
Q

Describe Third Generation Cephalosporins

A

Cefotaxime, Ceftriaxone, Ceftazidime
Cefixime is the oral agent
Have decreased activity against gram postive cocci except Streptococcus pneumoniae
Enhanced activity against gram negative bacilli
ability to penetrate the CNS
Ceftazidime is reserved for Pseudeomonas aeruginosa infections
Ceftriaxone uses the biliary system for excretion

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12
Q

Describe Fourth Generation Cephalosporins

A

Cefepime has enhanced activity against entrobacter and Citrobacter; active against Pseudomonas aeruginosa
Ceftaroline and Ceftobiprole have activity against MRSA, ampicillin sensitive E. faecalis, and penicillin resistant Streptococcus pneumoniae
Used almost always in hospital with a disease consultant as it is so broad spectrum

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13
Q

List adverse effects of Cephalosporins

A

Hypersensitivity
Diarrhea
Skin rash
Fever
Granulocytopenia
Hemolytic anemia
Biliary pseudolithiasis - ceftriaxone

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14
Q

Describe Carbapenems

A

Structure is related to beta-lactams
Imipenem given with cilastatin, meropenem
active agaisnt gram postive, gram negative, including Pseudomonas aeruginosa, and anaerobic organisms
Ertapenem has a long half life (OD) but poor activity against enterococcus sp. and Pseudomonas aeruginosa

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15
Q

Why is Imipenem always given with cilastatin?

A

Imipenem is inactivated by dihydropeptidases so, a peptidase inhibitor (cilastatin) is given with it.

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16
Q

Describe Monobactams

A

Monocyclic beta-lactam ring
Resistant to beta-lactamases
Aztreonam -s not available in Canada
active against gram negative bacilli including Pseudomonas aeruginosa
not active agaisnt ESBL or AmpC producers

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17
Q

What is MRSA?

A

MRSA stands for Methicillin resistant staphylococcus aureus;
resistant to the whole methicillin class as well as all penicillins
contains mecA gene and a low affinity PBP 2a

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18
Q

What agent is used in Canada for MSSA?

A

Cloxacillin, in the US nafcillin is used

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19
Q

What is ESBL? NDM-like?

A

ESBL is extended psectrum beta-lactamases that are found in E. coli and Klebsiella pneumoniae, resistance to even more drugs
NDM-like is New Dehli metallo-beta-lactamase ACinobacter baumannii; destroys even more drugs compared to ESBLs
Both have high resistnace to antibiotics, scary infections

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20
Q

What is a Concentration Independant Drug?

A

Threshold where no increase in effectiveness with increase of drug; want to keep at threshold level

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21
Q

What are the Macrolide Drugs?

A

Eryhtromycin
Clarithromycin
Azithromycin

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22
Q

Describe Macrolides (MOA, Resistance, Bacteria efficacy, etc.)

A

Attach to the 23S rRNA on the 50S subunit of bacterial ribosome resulting in inhibition of protein synthesis.
Bacteriostatic; time dependant killing
REsistance through methylation of the rRNA receptor, Inactivating enzymes, Active efflux
Covers gram positive organisms

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23
Q

Why is Erythromycin not seen much anymore?

A

Adverse effects; poor GI tolerability main reason it is not seen.
QT prolongation/ cardiac arrhythmias particularily when combined with CYP 3A inhibitors

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24
Q

What Activity dose Clarithromycin and Azithromycin have/ is used for? Why is it more used than Eryhtromycin

A

Active against Strep and Staph
Useful for some MRSA
less frequent dosing than erythromycin
Have less GI adverse effects than erythromycin

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25
True or False, If an organism is resistant to erythromycin it is resistant to Clarithromycin and Arithromycin as well.
True
26
What are some unique characteristics of azithromycin
Long half-life 5 days azithromycin = 10 day therapy Long intracellular concentrations
27
What are some main uses of macrolides?
URTI's STI's Acne Beta-lactam allergy patients
28
What are Drug interactions of macrolides?
Antiarryhthmics antidepressants benzodiazepines anticonvlsants statins CYP 3A4 substrates and inhibitors (for E and C)
29
Describe the MOA of Clindamycin and its spectrum of activtiy
Attach to the 23S rRNA on the 50S subunit of bacterial ribosome resulting in inhibition of protein synthesis. Bacteriostatic; time dependant killing Used for anaerobes, S. aureus including some MRSA as wellas streptococci. Nota DOC for any infection Used in penicillin allergies or resistant organisms
30
What are adverse effects of Clindamycin?
Nausea vomiting Diarrhea Rash C DIFF association Elevated LFTs Always be taken with water or liquid and sit upright for some time after taking to avoid esophageal irritation
31
what are the Tetracycline drugs?
Tetracycline Monocycline Doxycycline
32
What is the MOA of Tetracycline? How is there resistance?
Inhibit binding of aminoacyl-tRNA to the 30S unit of ribosome thereby inhbiting protein synthess Bacteriostatic High levels of resistance, methylation, change of 30S unit of ribosome, more
33
What is the spectrum of Tetracyclines?
Gram positive and Gram Negative but, high rates of resistance DOC for rickettsiae, bartonella, chlamydiae, and M. pneumoniae Nocardia P. acnes
34
What are adverse effects of Tetracyclines?
Upset GI Skin rashes Photosensitivity Yeast Overgrowth Deposited in bones and teeth - do not use in < 8 years of age hepatitis Minocycline associated with hypersenstivity reactions as well as dizziness, vertigo, and ataxia
35
What are drug interactions of Tetracyclines?
Divalent and Trivalent actions redice absorption Increased INR and bleeding with warfarin Some anticonvulsants can reduce tetracycline levels
36
What is glyclcycline?
Syntehtic analogue of tetracycline
37
What is the spectrum of glycylcycline?
Has activity against gram negative and gram positive organisms MRSA S. pneumoniae enterococci Salmonella Shigella Acinetobacter anaerobes
38
Explain how glycycline can be taken, how it is eliminated, and when it is used.
taken IV or IM eliminated through the biliary tract and feces Reserved for resistant organisms
39
What is the glycopeptide drug?
Vancomycin
40
What is the MOA of Vancomycin?
inhibits cell wall peptidoglycan synthesis Bactericidal
41
What is the resistance seen in Vancomycin?
VRE, VISA (Staph aureus super infection)
42
What is the spectrum of activtiy of Vancomycin?
gram positive cocci enterococci PRSP MRSA Clostridia Clostrioides SOme bacilli NO grame negative activity
43
How is Vancomycin adminsitered?
IV only for serious infections Orally for C. difficile as it is not orally absorbed Long infusion rates with drug monitoring
44
What are adverse effects of Vancomycin?
Nephrotoxicity Ototoxicity Red-man syndrome Granulocytopenia
45
What are some similar drugs to Vancomycin?
Teicoplann has similar structure Daptomycin is a lipopeptide adminstration is OD but has a major adverse effect of myopathy
46
What are the aminoglycoside drugs?
Streptomycin gentamicin tobramycin amikacin
47
What is the MOA of aminoglycosides? How is there resistance?
inhibit protein synthesis by inhibiting 30S subunit of bacterial ribosome Resistance through methylation of 16S rRNA-binding site, enzymatic destruction of teh drug, lack of permeability to the drug active efflux
48
When do you use tobramycin instead of gentamicin?
Only when there is resistance to gentamicin Gentamicin is the workhorse aminoglycoside
49
What is the spectrum for aminoglycosides?
aerobic gram negative bacilli Synergistic with penicillins for enterococci and streptococci Streptomycin for TB
50
How is aminoglycoside administered? How is it excreted?
IV or IM only Renal elimination Does not penetrate the CNS Therapeutic drig monitoring is often preformed
51
What are the adverse effects of aminoglycosides?
nephrotoxicity ototoxicity neuromuscular blockade
52
What are drug interactions Aminoglycoside
Other nephrotoxic drugs otehr ototoxic drugs neuromuscular blocking agents
53
What are the Fluoroquinolone drugs?
Ciprofloxacin Levofloxacin Moxifloxacin
54
What is the MOA of Fluoroquinolones and how is there resistnace?
inhibit DNA gyrase or topoisomerase II and IV Bacteriocidal: concentration dependant killing Resistance: alteration of the A or B subunit of DNA gyrase Mutation of ParC or ParE of topoisomerase IV change in outer membrane permeability efflux pumps
55
What is the spectrum of fluoroquinolones?
high activity agaisnt gram negative bacilli, Haemophilus sp, neisseriae, chlamydiae, etc.
56
What is ciprofloxacin most active against?
Pseudomonas aeruginosa
57
What organism is Levofloxacin active against?
S. pneumoniae
58
What organisms is Moxifloxacin active against?
Anaerobes
59
What are fluoroquinolones used for?
UTI's lower RTI's enteritis drug resistant mycobacterial infections
60
How are the fluoroquinolones eliminated?
Cipro and Levo renal elimination Moxi is biliary elimination
61
What are adverse effects of fluoroquinolones?
Nausea Vomiting diarrhea insomnia headache dizziness CNS effects skin rashes C DIFF PNS pain tendon rupture Can be very toxic; drugs in this category have been added and removed due to mortality such as hepatic failure causing and fatal skin affects
62
Why are fluoroquinolones not used in the elderly?
Tendon rupture risk side efect
63
How are fluoroquinolones taken?
Orally Very bioavailable, not often seen IV/IM
64
What are the drug interactions of fluoroquinolones?
divalent and trivalen cations QTc prolongation CYP 1A2 inhibtion result in increased levels of many drugs increased INR with warfarin
65
Why are fluoroquinolones not used often?
Many toxicities reserved for resistant organisms and situations where DOC cannot be used Not used in children < 18 years old
66
what is the MOA of SMX and TMP?
SMX is a structural analogue of PABA; comeptitively inhibits dihydrofolic acid synthesis TMP binds to dihydrofolte reductase therefore inhbiting the reduction of dihydrofolic acid to tetrahydrofolic acid BActeriostatic alone but bacteriocidal together
67
Can you use TMP alone?
Yes, is seen when there is sulfa allergies
68
What is SMX/TMP spectrum?
wide spectrum of gram negaive and gram positive, chlamydiae, nocardiae, and protozoa MRSA included No anaerobe activity or group A strep
69
What are SMX/TMP main uses?
UTI's Skin and sof tissue infection such as MRSA PJP
70
What are adverse effects of SMX/TMP?
Skin rashes; can be sever (SJS) hypersensitivity headache GI symptoms bone marrow suppression hyperkalemia and hyponatremia photosensitivity
71
What are drug interactions of SMX/TMP?
2C9 inhibitor; 3A4 substrate increased INR and bleeding with warfarin hypoglycemic agents increasing Potassium level drugs caution in renal dysfuncting and in first and 3rd trimester
72
What is the spectrum of activity of Metronidazole?
Anaerobes such as C. diff protozoa propionibacrium are resistant
73
How is metronidazole taken?
IV and Oral, very bioavailable
74
What are adverse effects of Metronidazole? Drug Interactions?
GI metalic taste headache dark urine peripheral neuropathy insomnia stomatitis Reaction with alcohol causing sweating, naseau, flushed, feeling very ill. Increased INR and bleeding with warfarin
75
What is the MOA of Linezolid?
inhibits protein synthesis bacteriostatic but, bactericidal against streptococci
76
What is the spectrum of activity of Linezolid?
streptococci, enterococci (includes VRE), staphylococci including MRSA
77
What is the main use of Linezolid? Why is it not commonly used?
REserved for mulit-drug resistant organisms, an alternative to vancomycin Not commonly used as it is the most expensive antibiotic available. Is both IV and oral dosage forms
78
What are adverse effects of Linezolid?
headache nausea, vomitting, diarrhea rash increased LFTs Myelosppression optic neuropathy peripheral neuropathy lactic acidosis decreased seizure threshold
79
What are drug interaction of Linezolid?
Increased serotonin syndrom risk with SSRI's and MAOI's rifampin decreases linezolid levels

PHAR 152 Microbes and Antibiotics (2 decks)

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