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Antibiotics Flashcards

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1
Q

What are the beta-lactam antibiotics?

A

Penicillins

Cephalosporins

Carbepenems

Monobactam

Beta-lactams inhibit transpeptidation of NAG and NAMs in bacterial cell walls

β-lactam antibiotics kill bacterial cells only when they are actively growing and synthesizing cell wall.

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2
Q

Beta-lactam - routes and general uses

A

Given Oral, IV, IM

Intrathecally is contraindicated

Poor CSF penetration, can reach therapeutic levels when meninges are inflamed.

T>MIC

Renally excreted - OAT

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3
Q

which beta-lactam antibiotics can treat CNS infections regardless of meningeal inflammation?

A

3rd generation cephalosporins - ceftriaxone and cefotaxime

2nd gen cephalosporin - cefuroxime

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4
Q

Mechanisms of resistance to β-lactam antibiotics

A

1 - penetration (intracellular organisms)

2 - Porins (like in gram-neg, need to get through porins in outermembrane to get to the peptidoglycan)

3 - pumps - drug efflux

4 - PBPs with low affinity for drug (penicillian binding protein)

5 - Penicillinases - hydrolyze (inactivate) drug

6 - peptidoglycan - organisms without cell wall (mycoplasma)

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5
Q

beta lactam resistant bacteria come in different classes,

A

Class A - Extended Spectrum Beta-lactamases - through several genes: TEM, SHV, CTX-M and KPC (klebsiella) Carbapenemase

Class A is passed by conjugation, expressed by gram-neg species especially

Class C – with genes AmpC and CMY organism displays resistance to broad and extended-spectrum beta-lactams

Class D – OXA-type: ESBLs and Carbapenemases

Class B -- genes: IMP, VIM, GIM, SPM, SIM: Carbapenemases. New Delhi (NDM-1): Carbapenemases
(class B type metallo-beta-lactamases)
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6
Q

How do bacterial biofilms affect therapy?

A

bacteria in biofilms are much less sensitive to antibiotics and tend to have decreased rates of growth

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7
Q

Hypersensitivity reactions to penicillins

A

Anaphylaxis: Rapidly progressive, life-threatening
-hypotension, bronchonstriction

angioedema, serum sickness (delayed, type III), immune hemolysis, rash or SJS

Fever; interstitial nephritis; vasculitis; neutropenia and
thrombocytopenia

Rx – Airway management, epinephrine followed by respiratory and cardiovascular support. Antihistamines or GCs as needed.

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8
Q

Name the non-immunologic side effects of beta-lactams

A

GI: mild to severe diarrhea; nausea; vomiting

Clostridium difficile infection - significant, pseudomembranous colitis

candidiasis infection

IM - pain, sterile imflammatory rxn at inj site, IV - phlebitis or thrombophlebitis

Intrathecal use is CONTRAINDICATED It can cause arachnoiditis or severe, fatal encephalitis

c. diff - gram pos, spore-forming, anaerobic bacillus

phlebitis - inflammation of vein wall

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9
Q

Drug Interactions of beta lactams

A

inhibition of OAT messes with probenecid and methotraxate

decreases effectiveness of oral contraceptives by decreasing estrogen recycling

interacts with gastric acid suppressors which increases c diff risk

tetracycline - reduce beta-lactam efficacy

decreases thyphoid vaccine efficacy

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10
Q

Natural Penicillin - What organisms do they treat?

A

useful for gram positive aerobes and anaerobes, N. meningitidis; H. influenzae; spirochetes

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11
Q

How are the different forms of natural penicillins administrured?

A

Penicillin G - IV and IM

Penicillin V - oral

repository Penicillin G - IM

  • Penicillin G procaine
  • Penicillin G benzathine
  • Penicillin G benzathine / procaine combo

poor penetration of CSF, inflamed meninges increases penetration

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12
Q

Resistance and cautions to Natural Penicillins

A

Beta-lactamases — s. aureus and gram-neg bacilli

PBPs with low affinity for beta-lactams —- s. pneumoniae, s. aureus, enterococcus faecium

gram-neg bacilli - drug cant pass through porins and have beta-lactamases

cautions - hypersensitivity, seizures, electrolyte distrurbances

jarisch-herxheimer reaction - complication of treatment of syphilis, thought to be a response to lipoproteins released by dying treponema pallidum

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13
Q

Penicillinase-Resistant Penicillins - name the drugs

A

Nafcillin
Oxacillin
Dicloxacillin
Cloxacillin

methicillin was the first in the class

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14
Q

Activity and therapeutic uses of penicillinase-resistant penicillins

A

activity against penicillinase-producing, methicillin-sensitive Staph aureus and Staph epidermidis

used for MSSA and MSSE

should not be used when penicillin can do the job

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15
Q

Resistance to penicillinase-resistant peniceillin and Adverse Effects

A

resistance - alteration of PBPs, expression of PBP2a (MecA gene) and inherent resistance (enterococci and listeria)

adverse effects special to these drugs are hepatitis and interstitial nephritis

hepatitis is through direct toxicity and hypersensitive rxn

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16
Q

Aminopenicillins - what are they?

A

extended spectrum penicillins

ampicillin (sometimes given with sulbactam)

amoxicillin (sometimes given with clavulanate)

Activity of Penicillin G plus Extended spectrum: gram-negative

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17
Q

Resistance to aminopenicillins

A

Class A TEM-1/SHV-1 β-lactamases found in H. influenza, N gonorrhoeae, E coli and klebsiella

Altered PBPs found in MRSA, pneumoniae, enterococcus

bacteroided fragilis - can be overridden with beta-lactamase inhibitor

Pseudomonas aeruginosa: inherently resistant

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18
Q

Adverse Effects of Aminopenicillins

A

non-allergic rash – pruritic maculopapular rash

viral infection - mononucleosis (EBV)

hypersensitivity reaction

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19
Q

Ampicillin-sulbactam: Broad use

A

parenteral only

includes repiratory, intra-abdominal, UTI and endocarditis

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20
Q

Amoxicillin-clavulanate Use

A

oral only

Respiratory, skin/skin structure, bite wounds and UTIs

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21
Q

Antipseudomonal Penicillins

A

Extended-spectrum penicillins

Piperacillin- tazobactam

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22
Q

Piperacillin-tazobactam

A

able to pass through porins in outer membrane because of polar side chains – pseudomonas aeruginosa and Enterobacteriaceae

broadest antibacterial spectrum of penicillins

Used for resistant gram-negative bacteria
-P. aeruginosa, indole-positive Proteus, Enterobacter

monotherapy is not recommended for p. aeruginosa - give with tobramycin or ciprofloxacin

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23
Q

Adverse Effects of Piperacillin-tazobactam

A

special effects of drugs:

exacerbation of CHF - drugs are manufactured as Na+ salts

abnormal platelet aggregation, thrombocytopenia

leukopenia and neutropenia with long-term use

seizure disorders

rash - especially in piperacillin use

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24
Q

β-Lactamase Inhibitors

A 
Clavulanic acid
Sulbactam
Tazobactam
Avibactam
Vaborbactam
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25
Mechanism of β-Lactamase Inhibitors
suicide inhibitors - molecules bind irreversibly to and inhibit bacterial beta-lactamases They are not antibiotics Most active against Ambler class A beta lactamases staphylococci N gonorrhoeae E coli H influenzae K pneumoniae M catarrhalis salmonella B fragilis shigella
26
Cephalosporins
First-generation - Cefazolin, Cephalexin Second-generation - Cefuroxime, Cefoxitin Third-generation - Ceftriaxone, Cefotaxime, Cefdinir, Ceftazidime, Ceftazidime-avibactam, Ceftolozanetazobactam Fourth-generation - Cefepime “Fifth”-generation - Ceftaroline
27
First Generation Cephalosprorins - drug names
Cefazolin* Cephalexin* Cefadroxil
28
Second-generation Cephalosporins - drug names
Cefuroxime Cefoxitin Others - cefaclor, cefprozil, loracarbef, cefotetan
29
Third - Generation Cephalosporins - drug names
Ceftriaxone Cefotaxime Cefdinir Ceftazidime (alone or with avibactam or tazobactam) others - ceftizoxime, cefpodoxime proxetil, cefditoren, ceftibuten, ceftixime
30
Fourth - Generation Cephalosporins - drug names
Cefepime
31
“Fifth”-generation Cephalosporins - drug names
Ceftaroline
32
General Properties of Cephalosporins
given IM, IV or oral with poor CSF penetration unless meningeal inflammation (with some exceptions) cross placenta and enters breast milk renal excretion of unchanged drug half life ranges from hour to 8 hours
33
Ceftriaxone
third generation cephalosporin biliary excretion
34
1st Generation Cephalosporin Spectra of Activity and Uses
Gram-positive -- MSSA and Streptococci Gram-negative -- PEcK (Proteus, E coli, Klebsiella) and respiratory bacteria Uses - skin and soft tissue infections(s. pyogenes, MSSA), otitis media, GU tract infections
35
cefazoline
1st generation cephalosporin - surgical propholaxis
36
2nd Generation Cephalosporin Spectra of Activity and Uses
Streptococci and MSSA (staph) Expanded gram-negative HeNPEcK (H.influenzae & PEcK - Proteus, E coli, Klebsiella) Cephamycins: B. fragilis uses - Uncomplicated skin / soft tissue, respiratory, GU infection
37
How is bacteroides fragilis treated?
resistant to all cephalosporins except: cefoxitin and cefotetan (cephamycins)
38
3rd Generation Cephalosporin Spectra of Activity and Uses
Activity of Penicillin G -- useful for gram positive aerobes and anaerobes, N. meningitidis; H. influenzae; spirochetes expanded gram negative spectrum ceftazidime has anti-pseudomonas activity
39
4th Generation Cephalosporin Spectra of Activity and Uses
Activity of Ampicillin (Ampicillin is Pen G plus extended spectrum gram negative) Extended spectrum gram negative + anti-pseudomonas Uses - reserved for treatment of severe infections
40
5th Generation Cephalosporin Spectra of Activity and Uses
Gram-positive aerobes and anti-MRSA with the gram negative activity of ceftriaxone (gram negative bacilli, some enterobaster, H. influenza, and Moraxella catarrhalis.) Uses - Skin/skin structure infections (including MRSA) and community-acquired pneumonia
41
What are the cephalosporins that can penetrate into CSF without meningeal inflammation?
cefuroxime cefotaxime ceftriaxone ceftazidime
42
ceftriaxone
third generation cephalosporin drug of choice for Gonorrhea and Lyme Disease infections also can be used for s. pneumonia (penicillin-sensitive), MSSA, gram negative bacilli, some enterobaster, H. influenza, and Moraxella catarrhalis
43
what drug options are available against Pseudomonas?
Piperacillin-tazobactam Ceftaroline (5th Gen) Cefepime (4th Gen) ceftazidime (2nd Gen) Carbapenems - except ertapenem
44
What types of infections are cephalosporins not good for?
penicillin-resistact S. pneumoniae, MRSA, MRSE (with exceptions), enterococcus, listeria monocytogenes, C. Diff KPC-producing enterobacteriacease, campylobacter jejuni, stenotrophomonas maltophillia, acinetobacter atypicals -- myoplasma, legionella pneumophila, chlamydia
45
Adverse effects of 3rd-Generation Cephalosporins
I.M. painful injection; I.V. thrombophlebitis Rare - renal tubular necrosis or interstitial nephritis
46
Adverse effects of Ceftriaxone
(third gen) biliary statis and cholestatic hepatitis in neonates - hyperbilirubinemia (with potential kernicterus) and lung and kidkey damage from precipitation of Ca2+ (give cefotaxime to neonates instead)
47
Adverse effects of Cefotetan
Hypoprothrombinemia by inhibition of Vit K activation Disulfiram-like reaction (alcohol consumption)
48
Carbapenems
Imipenem-cilastatin* Meropenem* Ertapenem* Doripenem
49
Characteristics and spectrum of Carbapenems
parentarel only, penetrates CSF short half life Broad Spectrum: gram-positive and gram-negative, aerobic and anaerobic Penicillin-resistant S. pneumonia Penicillin-sensitive Enterococcus faecalis Not affected by beta-lactamases but are suspectible to carbapenemases or metallo-β-lactamases (Klebsiella) ``` treatment of choice for: − ESBL-expressing Enterobacteriaceae − Pseudomonas aeruginosa, (may acquire resistance) • except ertapenem − Anaerobes, including B. fragilis ```
50
Resistance to Carbapenems
Acquired - Class A serine protease - Klebsiella pneumoniase carbapenemase - Class B metallo-β-lactamases AKA carbapenemases Intrinsic - MRSA, Enterococcus faecium, Clostridium difficile, Stenotrophomonas maltophilia
51
what do carbapenemases do?
They hydrolyze penicillins, cephalosporins, and carpenems They are not inhibited by beta-lactamase inhibitors
52
Therapeutic uses of Carbapenems
Empiric treatment of serious infections of hospitalized patients who have already recieved beta-lactam therapy -- lower respiratory, intra-abdominal, gynecological, skin, soft tissue, bone or joint infections Intra-abdominal and pelvic infections caused by gram-positive bacteria, enterobacteriaceae and anaerobes
53
Adverse effects of carbapenems
hypersensitivity reactions' Common side effects Seizures - greatest risk with imipenem and patients with renal insufficiency hematologic - bleeding, agranulocytosis, leukopenia GI - nausea, vomiting, diarrhea C. diff superinfection
54
Aztreonam - PK, Spectrum, Resistance
Monobactam - IV, IM; widely distributed; renal excretion gram-negative aerobes only - esp. aerobic cocci and bacilli, including P. aeruginosa Resistance: • Gram-positive bacteria • ESBLs; AmpC β-lactamase hydrolyze aztreonam • Some strains of Enterobacteriaceae and Pseudomonas (PBPs with low affinity for aztreonam)
55
Therapeutic Uses of Aztreonam
Infections by susceptible gram-negative bacilli - UTI's, LRT infections, septicemia, skin/skin structure infections, intra-abdominal infections, and gynecological infections aztreonam inhalation - in Cystic Fibrosis Patients with Pseudomonas aeruginosa Aztreonam should not be used alone for empiric therapy
56
Adverse Effects of Aztreonam
cross-reactivity with beta-lactams is limited, so hypersensitivity reactions are less common - Exception, ceftazidime Nausea/vomiting/diarrhea Thrombophlebitis and pain at injection site C. difficile superinfection reported - and can occur more than two months after treatment
57
Vancomycin - MOA and PK
glycopeptide - inhibit peptidoglycan polymerization - D-ala-D-ala poor absorption from gut so oral is only for local gut action, IV for systemic with slow infusion bc of red man syndrome only penetrates CSF with meningeal inflammation 6 hours half life, 24-h AUC/MIC and bacteriocidal (efficacy depends on the total amount of drug given in a 24 hour period)
58
Vancomycin - spectrum
Gram-positive pathogens only - Penicillin-resistant S. pneumoniae, MRSA and MRSE Enterococcus faecalis and E. faecium - bacteriostatic
59
Clinical Uses of vancomycin
MRSA / MRSE infections- - bacteremia, pneumonia, empyema, endocarditis, osteomyelitis, soft-tissue abscess Penicillin-resistant streptococcal and enterococcal infections - endocarditis and necrotizing fascitis meningitis due to penicillin resistant s. pneumoniae C. diff infection - first line (before it was metronidazole) Gram-positive infections in penicillin-allergic patients
60
Vancomycin Cautions - AEs and DIs
Adverse Effects - red man syndrome (thought to be caused by direct release of histamine and not immunologic), hypersensitivity, phlebitis, ototoxicity and nephrotoxcity Ototoxicity and nephrotoxicity are especially common when given with aminoglycosides NSAIDs may increase serum levels of vancomycin
61
Daptomycin
Cyclic lipopeptide with poor absorption, given IV only - forms a pore in the bacterial membrane causing loss of membrane pot. and cell death Inactivated by pulmonary surfactant half life - 8/9hrs bacteriocidal, AUC/MIC -- Efficacy correlates with total drug exposure to MIC ratio
62
Daptomycin spectrum and therapeutic uses
all gram-positive pathogens – aerobic, facultative, and anaerobic Effective against MRSA, MRSE, VISA, VRSA, and VRE treatment of complicated skin and soft tissue infections, bacteremia, and VRE right-sided endocarditis
63
What are the limitations of Daptomyicin
infections by gram-neg organism - ineffective left-sided endocarditis and pneumonia - because inactivated by pulmonary surfactant
64
Daptomycin Cautions
myopathy - monitor CK levels Eosinophilic pneumonia - important to monitor, happens 2 to 4 weeks post-therapy peripheral neuropathy pregnancy category b, excreted in breast milk not known to be safe in pediatrics interacts with statins (HMG-CoA reductase inhibitors)

Pharmacology (23 decks)

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