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Block 2 Flashcards

1
Q

this many antibiotic prescriptions written in the outpatient setting are unnecessary

A

50%

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2
Q

these are among the most commonly prescribed antibiotics

A

Azithromycin and amoxicillin

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3
Q

2 problems contributing to antibiotic resistance

A
  1. unnecessary outpatient prescriptions
  2. farm animals given human antibiotics
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4
Q

this many people are infected by drug-resistant bacteria every year in the US and this many die

A
  • 2 million infected
  • 23k die
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5
Q

epidemic in India

A

infants born with bacterial infections that are resistant to most known antibiotics

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6
Q

antibiotic definition

A

Natural substance produced by microbe to kill other microbes

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7
Q

antimicrobial definition

A

antibacterial, antifungal, and/or antiviral

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8
Q

4 Main Mechanisms of Action of Antimicrobial Agents

A

Inhibition of:

  1. cell wall synthesis
  2. cell memb fcn
  3. protein synthesis (translation + transcription)
  4. nucleic acid synthesis
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9
Q

examples of Folate synthesis inhibitors

A
  • Sulfonamides
  • Trimethoprim
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10
Q

examples of RNA Polymerase inhibitors

A

Rifampin

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11
Q

examples of Cell membrane inhibitors

A
  • Amphotericin
  • Ketoconazole
  • Polymixin
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12
Q

examples of Cell Wall synthesis inhibitors

A
  • Bacitracin
  • Fosfomycin
  • Vancomycin
  • Beta-lactams
    • carbapenems
    • cephalosporins
    • monobactams
    • penicillins
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13
Q

examples of DNA gyrase inhibitors

A

Fluoroquinolones

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14
Q

examples of Protein synthesis inhibitors

A
  • Aminoglycosides
  • Chloramphenicol
  • Clindamycin
  • Macrolides
  • Mupirocin
  • Streptogramins
  • Tetracyclines
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15
Q

Bacteriostatic agents

A
  • Inhibit microbe growth but do not reduce # of viable microbes (neutrophils reduce #)
  • Ex: reversible bacterial protein synthesis inhibitors
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16
Q

Bactericidal agents

A
  • kills susceptible microbes – reduces # viable microbes
  • Ex: bacterial cell wall synthesis inhibitors
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17
Q

this type of drug inhibits microbe growth but doesn’t reduce # viable microbes

A

bacteriostatic

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18
Q

this type of drug kills susceptible microbes, thereby reducing # viable microbes

A

bactericidal

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19
Q

bactericidal agents at low concentrations may do this

A

At low serum concentrations many bactericidal agents may only be bacteriostatic

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20
Q

can a drug be bactericidal and bacteriostatic? how?

A

A few antimicrobial agents are bactericidal against some microbes but bacteriostatic against others

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21
Q

which line represents control drug?

A

blue line

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22
Q

which line represents bacteriostatic drug?

A

green line (tetracycline or similar)

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23
Q

which line represents bactericidal drug?

A

red line (penicillin or similar)

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24
Q

Mechanism for most antimicrobial agents

A

Time-dependent killing

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25
Q

Time-dependent killing rate

A
  • Mechanism for most antimicrobial agents
  • Ability to kill microbes depends on length of time antimicrobial conc. > min bactericidal conc. (MBC)
  • Ability to inhibit further microbe growth depends on length of time antimicrobial conc. > min inhibitory conc. (MIC) at site of infection
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26
Q

Ability to kill microbes in time-dependent killing depends on this

A

length of time antimicrobial conc. > minimum bactericidal conc. (MBC)

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27
Q

ability to inhibit further microbe growth in time-dependent killing depends on this

A

length of time antimicrobial conc. > minimum inhibitory conc. (MIC) at site of infection

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28
Q

Concentration-dependent killing rate

A

Ability to kill microbes increases as antimicrobial concentration increases

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29
Q

examples of drugs that use concentration-dependent killing

A
  • Aminoglycosides
  • fluoroquinolones
  • daptomycin
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30
Q

Post-antibiotic effect

A
  • Microbial death / growth inhibition continues for a period of time after drug concentration drops below MBC or MIC at site of infection
  • Depends on antimicrobial + specific bacterial species
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31
Q

what does a graph of Time- vs. Concentration-Dependent Action look like?

A
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32
Q

what does a graph of concentration-dependent killing look like?

A
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33
Q

what does a graph of post-antibiotic effect look like?

A
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34
Q

Combination Antimicrobial Therapy definition

A

Usually 2+ agents w/different mechanisms of action

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35
Q

Combination Antimicrobial Therapy uses

A
  • single-microbe infections:
    • particularly resistant
    • difficult infection site
    • decreases resistance
  • polymicrobial infections:
    • gram (+), gram (-), and/or anaerobic bacteria
    • Diabetic foot infection, intra-abdominal wound infections, etc
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36
Q

try to identify pathogen of infection using these methods

A
  • Site of infection
  • Gram stain
  • Adequate Culture
  • Host factors
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37
Q

Types of Susceptibility testing

A
  • Disk diffusion
  • broth dilution
  • Etest method
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38
Q

susceptibility usually based on this

A

Susceptibility usually based on MIC – only obtain MBC by special request

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39
Q

what is the broth dilution test?

A
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40
Q

what is the Disk Diffusion Method?

A
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41
Q

susceptibility test determines/tells this about bacteria

A
  • Usually susceptibility reports only list whether bacteria is sensitive or resistant to antibiotics tested
  • Usually bacteria is reported to be sensitive to multiple antibiotics
  • Does not list actual MIC for each antibiotic
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42
Q

use these parameters to select antibiotic based on susceptibility

A
  • Select agent and dose that provides wide margin btwn achievable serum concentrations and the MIC or MBC
  • Always try to select most narrow spectrum agent
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43
Q

should you choose an agent with a narrow or wide spectrum?

A

Always try to select most narrow spectrum agent

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44
Q

examples of Intrinsic Resistance

A
  • Vancomycin vs gram-negative bacteria
  • Penicillin vs enteric bacteria
  • Aminoglycosides vs anaerobic bacteria
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45
Q

examples of acquired resistance

A
  • Many bacterial species over last 50 years of antibiotic era via gene transfer
  • New ‘gene pool’ created
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46
Q

7 mechanisms of antibiotic resistance

A
  1. Bacterial enzyme inactivation of antibiotics
  2. Alteration of cell wall target proteins
  3. Increase in cell wall thickness
  4. Decrease in cell membrane permeability
  5. Alteration of ribosomal targets
  6. Alteration of enzyme target
  7. Alteration of efflux pumps
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47
Q

example of antibiotic resistance via alteration of cell wall target proteins

A

penicillin-binding proteins (PGPs)

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48
Q

example of antibiotic resistance via decrease in cell membrane permeability

A

Alteration of porin channels

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49
Q

example of antibiotic resistance via Alteration of ribosomal targets

A

targeting 23s ribosomal RNA

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50
Q

example of antibiotic resistance via Alteration of enzyme target

A

targeting DNA gyrase

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51
Q

summarize antibiotic resistance in a picture

A
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52
Q

Experiment Demonstrating Multiple Drug Resistance Process using subtherapeutic amounts of oxytetracycline on chickens

A
  • 36 hrs: E. coli of chickens R to tetracycline
  • 3 months: E. coli multi-drug resistant (MDR)
  • 5 months: resistant intestinal E. coli appears in farm family members
  • 6 months: human intestinal E. coli now MDR although family not taking antibiotics or eating chickens
  • Intestinal flora of control chickens and farm neighbors remained normal
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53
Q

routes of antimicrobial administration

A
  1. Oral
  2. Parenteral
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54
Q

oral antimicrobial administration benefits/drawbacks

A
  • Safest route
  • Limitations:
    • bioavailabilty
    • drug/nutrient interactions preventing absorption
    • GI irritability
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55
Q

parenteral antimicrobial administration benefits/drawbacks

A
  • Fastest route giving the highest concentrations
  • Limitations:
    • toxicity (including catheter infections)
    • complexity of care
    • cost
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56
Q

ideal antimicrobial agent?

A

effective parenteral agent that can also be directly converted to oral form

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57
Q

can all antimicrobials be given via both administration methods?

A

no, some can only be given parenterally or orally

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58
Q

antimicrobial distribution in body

A
  • High conc / successful treatment expected in well-perfused tissues (plasma, muscle, kidney, etc)
  • Low conc / increased failure rates expected at sites not readily penetrated by most antimicrobials (bone, brain, prostate gland, abscesses, heart valves, etc)
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59
Q

antimicrobial metabolism

A
  • Some metabolized by liver
  • many excreted unchanged via biliary tract or kidney
  • Some may induce / inhibit metabolism of other drugs that depend on CYP 450
    • Macrolide antibiotics
    • Azole antifungals
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60
Q

renal antimicrobial excretion

A
  • Adjust dose in renal failure if renally excreted
  • Renally excreted antimicrobials preferred if treating lower UTIs
  • Doses generally lower for UTIs than for systemic infections due to high concentrations in urine – reduces chance for toxicity
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61
Q

antimicrobial doses for UTIs

A

Doses generally lower for UTIs than for systemic infections due to high concentrations in the urine – reduces chance for toxicity

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62
Q

Antimicrobial Toxicity

A
  • usually related to dose of antimicrobial agent
  • Must balance: enough to kill microbe at site of infection, but not enough to be toxic to human cells
  • Hypersensitivity reactions most common (sulfa, penicillin)
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63
Q

examples of toxicity from dose of antimicrobial

A
  • Most common:
    • Phlebitis from parenteral agents
    • photosensitivity reactions
    • GI intolerance
  • Renal failure possible for select drugs
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64
Q

Superinfection

A
  • Secondary to use of broad spectrum agents over period of time
  • Usually fungal infections
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65
Q

Idiosyncratic reactions to antimicrobials

A
  • Hepatotoxicity
  • Serum sickness
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66
Q

this determines choice of antimicrobial, dose, route, duration, and whether to use a combination regimen

A

Type of Infection:

  • Localized or systemic?
  • Signs of sepsis?
  • Site of infection?
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67
Q

considerations for antimicrobial choice for local vs systemic infections

A
  • May only need topical agent for small wound or ocular infection
  • Systemic infection means bacteria have spread to multiple organ systems – greater chance of sepsis
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68
Q

bacterial sepsis

A
  • Secondary to production of bacterial endotoxins
  • Fever, chills, hypotension, shock, organ failure
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69
Q

aggressive treatment needed for infections at these sites

A
  • blood
  • brain
  • bone
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70
Q

this may determine success/failure of treatment

A

immunocompetency

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71
Q

Immuno-incompetent

A
  • Absolute neutrophil count (ANC) < 500/ml3 (after chemo)
  • Taking immunosuppressive drugs (steroids or monoclonal Ab’s)
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72
Q

must use this type of therapy for immuno-incompetent patients

A

Must use bactericidal agents +/- combination therapy

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73
Q

Host Defense issues that can affect antimicrobial treatment

A
  • immunocompetency
  • concomitant disease states (diabetes)
  • Prostheses (infected)
  • Catheters (entry site; infected)
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74
Q

Direct Costs of Antimicrobial Therapy

A
  • Acquisition cost of drug(s)
  • Depends on cost of individual unit and duration of therapy
  • From pennies to thousands of dollars
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75
Q

Indirect Costs of Antimicrobial Therapy

A
  • Labor costs for parenteral administration (nursing and pharmacy time, bags, tubing, infusion devices, etc)
  • Monitoring (chemistries, cultures, pharmacokinetic analysis, etc)
  • Adverse reactions
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76
Q

Causes of Antimicrobial Failure

A
  • Drug resistance
  • Drug selection
  • Subtherapeutic dosing
  • Monotherapy
  • Poor penetration at site of infection
  • Inadequate duration
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77
Q

Reasons for Prophylactic Antibacterial Therapy

A
  • Prevention of infection during invasive procedures
  • Prevent disease transmission to close contacts of infected persons (Meningococcal, TB, flu)
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78
Q

When to use antibiotics for prevention of infection during invasive procedures

A
  • During dental and oral procedures to prevent endocarditis in patients with valvular heart disease
  • During surgical procedures to prevent systemic infection from bacteria on the skin or in the gastrointestinal tract
  • Give before procedure, not during!
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79
Q

gram(+) vs gram(-) bacteria in pictures

A
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80
Q

Antibacterials that inhibit bacterial cell wall synthesis

A
  • β-lactams
    • Penicillins
    • Cephalosporins
    • Monobactams
    • Carbapenems
  • Bacitracin
  • Fosfomycin
  • Vancomycin
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81
Q

Antibacterials that inhibit bacterial cell membrane synthesis

A
  • Daptomycin
  • Colistin (a polymyxin)
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82
Q

Antibacterials that inhibit bacterial protein synthesis

A
  • Macrolides
  • Tetracyclines
  • Aminoglycosides
  • Clindamycin
  • Linezolid
  • Mupirocin
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83
Q

Antibacterials that inhibit nucleic acid synthesis

A
  • Fluoroquinolones
  • Trimethoprim & sulfamethoxazole
  • Metronidazole
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84
Q

antitubercular agents

A
  • Isoniazid
  • Rifampin
  • Pyrazinamide
  • Ethambutol
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85
Q

picture of agents that inhibit bacterial cell wall and NA synthesis

A
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86
Q

Types of Penicillins

A
  • Natural Penicillins
  • Aminopenicillins
  • Extended-spectrum penicillins
  • Beta-lactamase inhibitor combinations
  • Penicillinase-Resistant Penicillins
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87
Q

Types of Cephalosporins

A

1st-5th generation

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88
Q

Types of Monobactams

A

Aztreonam

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89
Q

Types of Carbapenems

A
  • Imipenem-cilistatin
  • Meropenem
  • Ertapenem
  • Doripenem
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90
Q

Penicillins mechanism of action

A

Bind to penicillin-binding proteins (PBPs) on cell wall to inhibit further synthesis

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91
Q

Penicillins resistance mechanisms

A
  • Production of β-lactamase that destroy β-lactam ring of penicillin molecule (Staphylococcus sp, Hemophilus, Enterobacter, etc)
  • Mutation of PBP to prevent binding by penicillin (MRSA, penicillin-resistant pneumococcus)
  • Activity depends on affinity to PBPs or degree of resistance to β-lactamase enzymes
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92
Q

Penicillins Pharmacokinetics

A
  • Relatively short half-lives
  • Most eliminated by kidney unchanged
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93
Q

Penicillins adverse reactions

A

Hypersensitivity:

  • Immediate: anaphylaxis, urticaria, edema (Type I)
  • Accelerated: 1-72 hrs, urticaria
  • Delayed: days to weeks, rash, fever, serum sickness
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94
Q

this is common among all penicillins

A

Cross-sensitivity – Avoid if history of immediate or accelerated reaction with any of penicillin group

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95
Q

Penicillin G

A
  • 1st penicillin
  • Very acid-labile and only given IV with T ½ of 30 min
  • Dosed in units (1 million units = 0.6 gm)
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96
Q

Procaine penicillin G

A

Suspension given IM that lasts from 1-4 days depending on dose

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97
Q

Benzathine penicillin G

A

Suspension given IM that can last up to several weeks

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98
Q

Penicillin V

A

Oral form of penicillin that is more acid-stable

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99
Q

Use of natural penicillins (G & V)

A

Narrow spectrum antibiotic active against

  • Streptococci (S. pyogenes, S. pneumoniae)
  • Neisseria meningitidis
  • Clostridium sp
  • Treponema pallidum (syphilis)
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100
Q

Aminopenicillins

A

First of semisynthetic penicillins, which are all produced from 6-aminopenicillinamic acid

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101
Q

Ampicillin

A
  • Only used intravenously now
  • T ½ of 80 min so must give 4 times/day
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102
Q

Amoxicillin

A
  • Most common antibiotic prescribed
  • Oral equivalent of ampicillin b/c of better absorption
  • Can be given 2 to 3 times a day
  • Higher doses used if suspicion of penicillin-resistant pneumococcus
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103
Q

Most common antibiotic prescribed

A

Amoxicillin

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104
Q

Idiosyncratic reactions to aminopenicillins

A
  • Ampicillin rash with either product – up to 10% of individuals
  • Up 60% incidence of rash if mononucleosis present or taking allopurinol for gout
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105
Q

uses of Aminopenicillins

A
  • Active against common upper respiratory tract pathogens
    • S. pyogenes
    • S. pneumoniae (most strains)
    • Hemophilus influenza (most strains)
  • Some activity against Enterococcus and common community gram(-) bacteria (E. coli, Proteus sp)
  • NO activity against Staphylococcus
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106
Q

these types of penicillin have NO activity against Staphylococcus

A
  • aminopenicillins
  • extended-spectrum penicillins
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107
Q

Extended-Spectrum Penicillins

A

aka anti-pseudomonal penicillins

  • Piperacillin (Pipracil)
  • Carbenicillin
  • ticarcillin
  • mezlocillin
108
Q

piperacillin

A
  • Most common extended-spectrum penicillin
  • Only given IV
  • Usually used in combination with tazobactam (Zosyn)
  • Excreted via biliary tract
109
Q

Carbenicillin, ticarcillin, mezlocillin

A

older extended-spectrum penicillins rarely used now

110
Q

adverse effects of extended-spectrum penicillins

A
  • Sodium overload with high doses
  • Thrombocytopenia with high doses
111
Q

Uses for Extended-Spectrum Penicillins

A
  • Extended activity against gram(-) bacteria
  • Pseudomonas aeruginosa activity
    • Combine w/aminoglycoside antibiotic for serious P. aeruginosa infections
  • Bacteremia, pneumonia, neutropenic fever
  • Retains activity against Enterococcus
  • No activity against Staphylococcus
112
Q

β-Lactamase Inhibitor/Penicillin Combinations

A
  • Clavulanic acid
    • With amoxicillin = Augmentin (now generic)
    • For diabetic foot wounds, bites, Staphylococcal infections
  • Sulbactam
    • With ampicillin = Unasyn
  • Tazobactam
    • With piperacillin = Zosyn
    • Most widely used IV antibiotic in hospitals
    • Active against most gram (+), gram (-), and anaerobic bacteria
113
Q

Most widely used IV antibiotic in hospitals

A

Tazobactam (+ piperacillin = Zosyn)

114
Q

β-Lactamase Inhibitor/Penicillin Combination Mechanism of Action

A
  • β-lactamase inhibitors preferentially combine with bacterial β-lactamase enzymes and inactivate them
  • Make penicillins more active against previously resistant bacteria (Staphylococcus, gram (-), anaerobes)
  • Does not increase activity against bacteria resistant b/c of altered PBPs (ie. MRSA)
  • Same kinetics, adverse effects, etc as penicillins used alone
115
Q

Penicillinase-Resistant Penicillins

A
  • Semisynthetic penicillins specifically developed to treat Staphylococcus resistant to penicillins
  • First agent was methicillin, but removed from market secondary to cases of interstitial nephritis
116
Q

Methicillin

A
  • Penicillinase-Resistant Penicillin
  • introduced in 1960
    • 1st methicillin-resistant (MRSA) strain appeared in 1961 in London
    • mecA gene codes for new PBP2a
  • removed from market secondary to cases of interstitial nephritis
117
Q

what happened to staph to make it MRSA?

A

mecA gene codes for new PBP2a

118
Q

Nafcillin

A
  • Penicillinase-Resistant Penicillin
  • Only used IV
  • Must give 4 to 6 times per day
  • Risk: Can cause severe phlebitis at IV site as well as serum sickness reactions
119
Q

Dicloxicillin

A
  • Penicillinase-Resistant Penicillin
  • Oral equivalent of nafcillin
120
Q

mechanism by which beta-lactams develop antibiotic resistance?

A
  • synthesize beta-lactamase –> destroy penicillin beta-lactam ring
  • mutation of PBP to prevent penicillin binding
121
Q

most likely problem when a patient on chronic tetracycline for acne suddeny develops diarrhea cultured for C. diff?

A

superinfection

122
Q

what antibiotic can be used in patients with history of penicillin or cephalosporin hypersensitivity reactions and/or patients with beta-lactam allergies?

A

Aztreonam (Azactam)

  • Monocyclic β-lactam ring
  • Activity similar to ceftazidime (3rd gen)
  • Activity against many gram(-) bacteria, Pseudomonas
  • No activity against gram-positive bacteria
123
Q

preferred first-choice agent for MRSA treatment?

A

Vancomycin

124
Q

Vancomycin resistance uses this mechanism

A

decreased binding of drug to cellular target

  • remember, Vanco inhibits cell wall synthesis by blocking elongation of peptoglycan molecule
125
Q

Other choices for MRSA treatment

A
  • linazolic acid
  • 1st gen cephalosporins
  • streptograms
126
Q

Ciprofloxacin mechanism of action

A

DNA gyrase / topoisomerase II & IV inhibitor (Fluoroquinolone antibiotic)

127
Q

best choice for syphilis management

A

penicillin – bind PBPs to inhibit cell wall synthesis

128
Q

if a patient is allergic to one penicillin, can you give them a different one?

A

no, they are likely to be allergic to all penicillins

129
Q

most appropriate treatment for infection around implanted catheter includes a drug that interacts with what substance?

A

D-alanyl-D-alanine dipeptide in cell wall (Vancomycin)

130
Q

these drugs interact with transpeptidase enzyme in cell wall

A

penicillins, beta-lactam antibiotics

*transpeptidase = PBP

131
Q

imipenem would be contraindicated in a patient w/Hx of alcoholism and convulsions because of which of his conditions?

A

convulsions: has neurotoxicity at high doses and can actually cause seizures

132
Q

carbapenems are contraindicated in patients with these conditions

133
Q

what can prevent tetracycline binding?

A
  • Cations such as calcium will bind to tetracyclines and prevent absorption
  • Avoid giving with dairy products or antacids
134
Q

this drug is one of the most common causes of superinfection

A

tetracycline – broad-spectrum, kills everything –> C. Diff

135
Q

Bacterial resistance tends to develop quickly with use of this type of drug

A

Cephalosporins – that’s why there are so many generations

136
Q

patient w/an amoeba was treated w/first-line drug therapy. he drank whiskey that evening, and quickly developed severe nausea, vomiting, palpitations, chest pain, profuse sweating. what was the drug?

A

metronidazole (disulfiram-like effect)

137
Q

patient presents to ED with fever, altered sensorium, and neck stiffness. what drug should be used?

A

Ceftriaxone

138
Q

what drug could cause a serious adverse reaction if combined with common anesthesia drugs?

A

aminoglycosides (Gentamicin, etc) – block NM junction

139
Q

an antibiotic binds to 50s ribosomal subunit, inhibiting translocation (protein synth). it also causes severe diarrhea in this patient, who is being treated for chlamydia. what drug is causing the diarrhea?

A

Macrolide (Clindamycin, etc) – stimulate motilin receptors

140
Q

Pseudomonas aeruginosa treated with this

A
  • Extended-Spectrum Penicillins
  • if particularly bad, add aminoglycoside
141
Q

Augmentin

A
  • Clavulanic acid + amoxicillin
  • β-Lactamase Inhibitor/Penicillin Combination
  • For diabetic foot wounds, bites, Staphylococcal infections
142
Q

Unasyn

A
  • Sulbactam + ampicillin
  • β-Lactamase Inhibitor/Penicillin Combination
143
Q

Zosyn

A
  • Tazobactam + piperacillin
  • β-Lactamase Inhibitor/Penicillin Combination
  • Most widely used IV antibiotic in hospitals
  • Active against most gram (+), gram (-), and anaerobic bacteria
144
Q

Cephalosporins

A
  • Similar to penicillins (share β-lactam ring) but more stable to β-lactamases
  • Semisynthetic drugs derived from Cephalosporium
  • MOA – Similar to penicillin
145
Q

Bacterial Resistance to Cephalosporins

A
  • Bacteria producing variety of β-lactamase enzymes that destroy β-lactam ring of molecule
  • No activity against MRSA except for new drug, ceftaroline
  • No activity against Enterococcus sp or Listeria
146
Q

ceftaroline

A

new cephalosporin w/activity against MRSA

147
Q

Classification of cephalosporins

A
  • Classified into 5 major groups (generations) based on spectrum of activity
  • W/each succeeding generation, more gram (-) but less gram (+) activity
148
Q

Pharmacokinetics of Cephalosporins

A
  • Half-lives vary from short to very long
  • Most eliminated by kidney unchanged
149
Q

Important adverse reactions of cephalosporins

A
  • Hypersensitivity reactions less common than penicillins
  • Cross-sensitivity with penicillins is minimal unless history of anaphylactic reaction with penicillins
  • Bacterial resistance tends to develop quickly with use – reason why so many cephalosporins were developed
150
Q

1st Generation IV Cephalosporins

A
  • Cefazolin
  • (Kefzol, Ancef)
  • usually given every 8 hrs
151
Q

1st Generation Oral Cephalosporins

A
  • Cephalexin (Keflex) – short T ½
  • Cephradine (Velocef)
  • Cefadroxil (Duracef) – long T ½
152
Q

1st Gen Cephalosporin Uses

A
  • Active against Streptococcus sp and methicillin-sensitive Staph (MSSA)
  • Also active against strains of E. coli and Klebsiella sp
153
Q

Cefazolin

A
  • 1st Gen IV Cephalosporin
  • widely used in hospitals for wound infections and surgical prophylaxis
154
Q

Cephalexin

A
  • 1st Gen Oral Cephalosporin
  • widely used in community for Staph and Strep infections
155
Q

2nd Generation IV Cephalosporins

A
  • Cefuroxime (Ceftin)
  • Cefoxitin
156
Q

2nd Generation Oral Cephalosporins

157
Q

Cefuroxime

A
  • 2nd Generation IV/Oral Cephalosporin
  • for upper respiratory infections
158
Q

Cefoxitin

A
  • 2nd Generation IV Cephalosporin
  • for abdominal and gynecologic infections b/c of increased anaerobic activity
159
Q

2nd Generation Oral Cephalosporins

A
  • Cefuroxime (can switch from IV)
  • Cefaclor
  • Cefprozil
160
Q

Uses for 2nd Gen Cephalosporins

A
  • Increased activity against gram(-) bacteria incl Klebsiella pneumoniae, Hemophilus influenzae, and Moraxella catarrhalis
  • For community-acquired pneumonia and more resistant upper respiratory infections such as otitis media
161
Q

Activity of 3rd Generation Cephalosporins

A

IV forms are much more active than oral forms

162
Q

3rd Generation IV Cephalosporins

A
  • Cefotaxime (Claforan) – short T ½
  • Ceftriaxone (Rocephin) – long T ½, give once daily IM/IV
  • Ceftazidime (Fortaz)
163
Q

3rd Generation Oral Cephalosporins

A
  • Cefixime (Suprax)
  • Cefpodoxime (Vantin)
164
Q

Uses for 3rd Generation Cephalosporins

A
  • IV wide range of activity against gram (-) and gram (+) bacteria
  • Used for nosocomial infections, pneumonia, meningitis, advanced Lyme disease
  • No activity against anaerobic bacteria
165
Q

Ceftazidime

A
  • only 3rd gen w/activity against Pseudomonas
  • Useful alternative to piperacillin
166
Q

4th Generation Cephalosporin

A
  • Cefepime (Maxipime) – only given IV
167
Q

Cefepime

A
  • 4th Generation Cephalosporin
  • More resistant to chromosomal β-lactamase enzymes (produced by Enterobacter sp)
  • Good activity against Enterobacteriaceae and Pseudomonas aeruginosa
  • Unlike ceftazidime, good activity against penicillin-resistant Strep pneumoniae
168
Q

5th Generation Cephalosporin

A

Ceftaroline (Teflaro) – only given IV

169
Q

Ceftaroline

A
  • First beta-lactam approved for MRSA
    • high affinity for PBP2a encoded by mecA gene
  • Otherwise, antibacterial spectrum most similar to 3rd generation cephalosporin, ceftriaxone
  • As with ceftriaxone, no activity against Pseudomonas or Enterococcus species
170
Q

First beta-lactam approved for MRSA

A

Ceftaroline

171
Q

Monobactam

A

Aztreonam (Azactam) - only given IV

172
Q

Aztreonam

A
  • Monobactam
  • monocyclic β-lactam ring
  • No cross-sensitivity in pts w/Hx severe penicillin or cephalosporin hypersensitivity rxns
  • Activity similar to ceftazidime (3rd gen) w/activity against many gram(-)bacteria, Pseudomonas
  • No activity against gram(+) bacteria
  • Used for patients with β-lactam allergies
173
Q

this drug used for patients with β-lactam allergies

174
Q

Carbapenems

A
  • Broadest spectrum of antibacterial drugs available
  • Reserved for life threatening or multi-resistant infections
  • Structurally related to other β-lactam antibiotics
  • All given intravenously
175
Q

Broadest spectrum of antibacterial drugs available

A

Carbapenems

176
Q

Imipenem-cilistatin

A
  • Carbapenem
  • Cilistatin inhibits enzyme that hydrolyzes imipenem in kidney – helps increase T ½, but still give every 8 hrs
177
Q

Examples of carbapenems

A
  • Doripenem (Doribax) – now preferred agent
  • Imipenem-cilistatin (Primaxin)
  • Meropenem (Merrem)
  • Ertapenem (Invanz)
178
Q

Doripenem

A
  • Carbapenem
  • Now preferred agent
  • More active against Pseudomonas than others
179
Q

Uses for Carbapenems

A
  • Serious polymicrobial and nosocomial infections due to highly resistant bacteria
  • Imipenem, doripenem, and meropenem (but not ertapenem) also have activity against Pseudomonas
180
Q

Side Effects of Carbapenems

A
  • Can be neurotoxic at higher doses (seizures)
  • Greater chance of superinfections
  • High cost
  • Some cross sensitivity in penicillin-allergic patients
181
Q

Bacitracin

A
  • Cell Wall Synthesis Inhibitor
  • Active only against gram(+)
  • Only used topically to treat Strep and Staph skin infections
    • Systemic: Highly nephrotoxic
    • Oral: Poorly absorbed
182
Q

Fosfomycin

A
  • phosphonic antibiotic
  • Cell Wall Synthesis Inhibitor
  • bactericidal in urine – inhibits peptidoglycan synthesis
  • Oral agent now ecommended for gram(-) UTIs if pt suspected/known resistance to sulfa and fluoroquinolones
183
Q

Nitrofurantoin (Macrodantin)

A
  • Cell Wall Synthesis Inhibitor
  • Only used for lower UTIs (bactericidal against E. coli, Enterococcus, and other common UTI orgs)
  • Commonly causes GI irritation, nausea, and vomiting
  • Avoid in elderly b/c increased risk of pneumonitis and neuropathy
  • Contraindicated in renal failure
184
Q

Vancomycin

A
  • Glycopeptide molecule with high molecular weight
  • inhibits cell wall synthesis by blocking peptoglycan elongation
185
Q

Bacterial Susceptibility to Vancomycin

A
  • Bactericidal against most gram(+) including those resistant to β-lactams
  • No activity against gram(-)
  • Some enterococci have become resistant (VRE)
    • Big worry that this mutant gene can be transferred to Staph
186
Q

Vancomycin Administration

A
  • Usually given IV
  • Not absorbed orally.
  • Oral vancomycin remains in GI tract, only used to treat C. difficile colitis
187
Q

Vancomycin Pharmacokinetics

A
  • Renal elimination directly proportion to creatinine clearance
  • Narrow therapeutic index – must monitor peak and trough levels
188
Q

Important adverse reactions to Vancomycin

A

Red Man Syndrome

  • infusion reaction due to massive histamine release if given too fast or in too high a dose
  • treat with antihistamine

Ototoxicity at higher doses

189
Q

Red Man Syndrome

A
  • reaction to Vancomycin
  • infusion rxn due to massive histamine release if given too fast or in too high a dose
  • treat with antihistamine
190
Q

Vancomycin uses

A
  • Reserved for known or suspected MRSA
  • used in combination with aminoglycoside for serious Enterococcus infections
  • Oral vanc only used to treat pseudomembranous colitis secondary to C. difficile
191
Q

Bacterial Cell Membrane Synthesis Inhibitors

A
  • Daptomycin (Cubicin)
  • Colistin
192
Q

Daptomycin

A
  • Cell Membrane Synthesis Inhibitor
  • Unique cyclic lipopeptide active against gram(+)
  • only available in IV form
  • Old drug making comeback for treating vancomycin-resistant bacteria
  • Concentration-dependent activity
193
Q

Colistin

A
  • Cell Membrane Synthesis Inhibitor
  • Also known as polymyxin E that was used in 1920’s
  • Intravenous
  • Starting to be used for MDR-resistant bacteria such CRE (carbapenemase-resistant Enetrobacteriaceae)
  • Nephrotoxic like aminoglycosides
194
Q

Bacterial Protein Synthesis Inhibitors

A
  • Macrolides
  • Tetracyclines
  • Aminoglycosides
  • Clindamycin
  • Linezolid
  • Mupirocin
195
Q

Examples of Macrolides

A
  • Erythromycin
  • Clarithromycin
  • Azithromycin
196
Q

Examples of Tetracyclines

A
  • Tetracycline
  • Doxycycline
  • Tigecycline
197
Q

Examples of Aminoglycosides

A
  • Gentamicin
  • Tobramycin
  • Amikacin
  • Streptomycin
  • Neomycin
198
Q

Miscellaneous Bacterial Protein Synthesis Inhibitors

A
  • Clindamycin
  • Linezolid
  • Mupirocin
199
Q

Macrolide Antibiotics Mechanism of Action

A

reversibly bind to 50s ribosomal subunit

200
Q

Bacterial Susceptibility to Macrolides

A
  • Usually bacteriostatic
  • Streptococcus sp and Staphylococcus
  • Resistance gradually increasing
  • Some activity against H. influenzae and Bordetella
  • Activity against atypical bacteria (Mycoplasma, Legionella, Chlamydophyla) that cause pneumonia
201
Q

Macrolide Uses

A
  • For upper and lower respiratory infections potentially due to atypical bacteria
  • IV azithromycin used extensively in hospitals for pneumonia
  • For penicillin-allergic patients
  • For Chlamydia trachomatis STD infections
  • Clarithromycin for Mycobacterium Avian Complex (MAC)
202
Q

Clarithromycin

A
  • Macrolide
  • Used for Mycobacterium Avian Complex (MAC)
  • better absorbed than erythromycin
  • Higher serum levels and lower GI levels
    • fewer GI adverse effects
  • Not available in IV
  • Can give 2x/day
  • Same drug interactions as erythromycin but stronger
203
Q

Azithromycin

A
  • Macrolide
  • Given IV and orally
    • IV used extensively in hospitals for pneumonia
  • Most popular and safest macrolide antibiotic
  • T ½ = 60 hrs, requires loading dose and 1x/day dosing (Z-Pack)
  • Only have to give for 3 to 5 days
  • Minimal adverse reactions
  • No drug interactions
204
Q

Erythromycin

A
  • IV form rarely used anymore
  • Available orally
  • Must give 3-4x/day
  • Adverse effects
    • Oral form: dose-dependent effect on peristalsis (motilin) –> abd pain, diarrhea
    • High IV doses: ototoxicity
    • Inhibits CYP 450 3A4 (metabolizes 50% of drugs)
    • Increases serum levels of statins, benzodiazepines, Ca channel blockers, cyclosporine, etc
205
Q

Most popular and safest macrolide antibiotic

A

Azithromycin

206
Q

Tetracyclines Mechanism of Action

A

reversibly bind to bacterial 30s ribosomal subunit

207
Q

Bacterial Susceptibility to Tetracyclines

A
  • Usually bacteriostatic effect
  • Activity against many gram(+) and gram(-) bacteria
  • Activity against rickettsiae, chlamydiae, mycoplasma, and some protozoa
208
Q

Important adverse reactions of Tetracyclines

A
  • GI irritation
  • Photosensitivity
  • Can cause skeletal deformities in developing fetus and discoloration of tooth enamel in children and fetus
    • (tetracycline loves calcium! Will bind to it and interfere w/bone and tooth development)
  • Hepatotoxicity possible with extended use
  • One of the most common causes of superinfection
209
Q

One of the most common causes of superinfection

A

Tetracyclines

210
Q

Important drug interactions with Tetracyclines

A
  • Cations such as calcium will bind and prevent absorption
  • Avoid giving with dairy products or antacids
211
Q

Uses for Tetracyclines

A
  • Lyme Disease
  • Erlichiosis
  • Rocky Mountain Spotted Fever
  • Atypical pneumonia
  • Pelvic inflammatory disease
  • Tetracycline and minocycline for acne
212
Q

Tetracycline

A

Rarely used now because of lower bioavailability and short T½ - have to give 4x/day

213
Q

Doxycycline

A
  • Most popular tetracycline
  • Give both IV and oral (good bioequivalence)
  • Long T½
  • Can be given 1-2x/day depending on infection
214
Q

Minocycline

A
  • Popular for acne due to high distribution in skin
  • Very expensive
  • Long-term can cause anemias
215
Q

Tigecycline

A
  • Derivative of minocycline approved in 2005
  • IV (not oral) approved for complicated skin and intra-abdominal infections
  • Not affected by 2 major mechanisms of tetracycline resistance, but still only bacteriostatic activity
  • Active against gram(+) (including MRSA), gram(-), and anaerobic bacteria
  • Not active against Pseudomonas or Proteus species
  • Reserve for antibiotic-resistant infections
  • Adverse effects: frequent nausea and vomiting
216
Q

Aminoglycoside Antibiotics Mechanism of Action

A

irreversibly bind to bacterial 30s ribosomal subunit

217
Q

Bacterial Susceptibility to Aminoglycoside Antibiotics

A
  • Bactericidal activity against most gram(-), including Pseudomonas
  • Streptococci are resistant to agents when used alone
  • Synergistic activity combined with β-lactams
218
Q

Uses for Aminoglycoside Antibiotics

A

Bacteremia, pneumonia, intra-abdominal infections, and other serious infections from gram(-)s

219
Q

Pharmacokinetics of Aminoglycoside Antibiotics

A
  • Only available IV or IM (not absorbed orally)
  • Short T½ – 2-3 hrs
  • Concentration-dependent killing – high dose 1x/day
  • Eliminated renally; accumulate in renal failure
  • Monitor peak and trough levels – narrow therapeutic index
220
Q

Important adverse reactions of Aminoglycoside Antibiotics

A
  • Very nephrotoxic – can accumulate in renal tubules and cause acute renal failure
  • Also ototoxic at high doses for extended periods of use
  • Block NM junctions – implications for anesthesia
221
Q

Streptomycin

A
  • First aminoglycoside
  • Used IV or IM as 2nd-line therapy for active TB
222
Q

Neomycin

A
  • Most toxic aminoglycoside – never used IV
  • Used in topical formulas in combination with other antibiotics
  • Oral form sometimes used for prophylaxis before elective bowel surgery
223
Q

Tobramycin

A

Given IV, IM, or inhaled for cystic fibrosis patients with Pseudomonas pneumomniae

224
Q

Clindamycin Mechanism of Action

A

binds to same 50s ribosomal subunit as macrolides

225
Q

Bacterial Susceptibility to Clindamycin

A
  • Bacteriostatic activity
  • Inhibits Streptococci, Staphylococci, and Pneumococci
  • Inhibits anaerobic bacteria such as Bacteroides fragilis and Clostridium perfringies
226
Q

Uses for Clindamycin

A
  • Anaerobic infections: intra-abdominal wounds, gynecologic infections, abscesses, aspiration pneumonia
  • Gram(+) infections in penicillin-allergic patients
  • Newly discovered community-acquired MRSA
227
Q

Clindamycin Pharmacokinetics

A
  • Can be given IV or orally
  • Metabolized by liver
228
Q

Important adverse reactions of Clindamycin

A
  • GI upset: nausea, diarrhea
  • Primary cause of antibiotic-associated pseudomembranous colitis
229
Q

Primary cause of antibiotic-associated pseudomembranous colitis

A

Clindamycin

230
Q

Linezolid Mechanism of Action

A

oxazolidinedione with unique activity against bacterial 50s ribosomal subunit

231
Q

Bacterial Susceptibility to Linezolid

A
  • Bacteriostatic activity
  • Active against most gram(+)s, including most strains resistant to other antibiotics
  • Resistance may occur with overuse
232
Q

Uses for Linezolid

A

Should be reserved for infections caused by multidrug-resistant bacteria such as VRE and MRSA

233
Q

Pharmacokinetics of Linezolid

A
  • Given oral or IV with 100% bioavailability
  • Metabolized by the liver with T ½ of 4-6 hrs
234
Q

Important adverse reactions of Linezolid

A

Hematologic toxicity – can cause thrombocytopenia and neutropenia with extended use

235
Q

Cost of Linezolid

A

$2700 for 10 days of oral therapy

236
Q

Mupirocin (Bactroban)

A
  • Unrelated to other antibiotics
  • Used in topical preps for treating Staph infections
    • Should be reserved for suspected/definite MRSA to avoid resistance
  • Special nasal formulation available to eliminate MRSA carriage
  • Also used for impetigo caused by Strep or Staph
237
Q

Nucleic Acid Synthesis Inhibitors

A
  • Usually bactericidal
  • Inhibition of bacterial DNA gyrase (Fluroquinolones)
  • Inhibition of bacterial folic acid synthesis (Trimethoprim & sulfamethoxazole)
  • Disruption of bacterial DNA helix (Nitroimidazoles such as metronidazole)
238
Q

Fluoroquinolone Antibiotics

A
  • Bacterial DNA Gyrase Inhibitors
  • 3 generations
239
Q

1st Gen Fluoroquinolones

A

Nalidixic acid

240
Q

2nd Gen Fluoroquinolones

A
  • Norfloxacin
  • Ciprofloxacin
  • Ofloxacin
  • Lomefloxacin
  • Enoxacin
241
Q

3rd Gen Fluoroquinolones

A
  • Levofloxacin (Levaquin)
  • Moxifloxacin (Avelox)
  • Gemifloxacin (Factive)
242
Q

Fluoroquinolones Mechanism of Action

A

inhibit DNA gyrase and topoisomerase that are essential for maintaining bacterial DNA structure and function

243
Q

Bacterial Susceptibility to Fluoroquinolones

A
  • Bactericidal activity against most gram(-)s
  • Active against atypical bacteria
  • 3rd gen agents also have good activity against gram(+)s (except staph)
244
Q

Uses for Fluoroquinolones

A
  • Complicated UTIs and prostatitis
  • Serious infections secondary to gram(-)s – bacteremia, intra-abdominal infections
  • 3rd gen agents used for severe pneumonia
  • Infectious diarrhea secondary to Salmonella and Shigella
  • Penicillin-resistant anthrax
245
Q

Pharmacokinetics of Fluoroquinolones

A
  • Most available as both IV and oral forms
  • Distribute very well into most tissues
  • Most excreted renally
246
Q

Important adverse reactions of fluoroquinolones

A
  • Causes arthropathy in developing animals - avoid in children less than 18 years old and during pregnancy
  • Achilles tendon rupture
  • Neurotoxic in high doses (irritability, seizures)
247
Q

Important drug interactions w/fluoroquinolones

A
  • Absorption of oral forms inhibited by cations such as calcium, magnesium, iron, and zinc (multivitamins and antacids)
  • Inhibit metabolism of caffeine and theophylline
248
Q

Ciprofloxacin

A
  • Most commonly used 2nd gen fluoroquinolone
  • Advantage: only quinolone w/activity against Pseudomonas aeruginosa
  • Disadvantages:
    • Poor activity against gram(+)s
    • Shorter T½ requires IV or oral dose bid
249
Q

Norfloxacin

A
  • 1st fluoroquinolone
  • Still used for UTIs
  • does not achieve high enough serum levels for systemic infections
250
Q

Uses for 3rd Gen Fluoroquinolones

A
  • Aka the “respiratory fluoroquinolones”
  • Active against gram(-)s
  • Active against most bacteria responsible for respiratory infections (atypical bacteria, MDR Strep pneumoniae)
251
Q

Levofloxacin

A
  • L-isomer of ofloxacin
  • Most common fluoroquinolone used for variety of serious infections
  • Renal elimination with normal T ½ = 7 hrs
  • Given once daily IV or oral
252
Q

Moxifloxacin

A
  • 3rd gen Fluoroquinolone w/better activity against anaerobics than levofloxacin
  • Metabolized by liver, so should not be used for UTIs
  • Given once daily IV or oral
253
Q

Gemifloxacin

A
  • Newest fluoroqunolone
  • Only available as oral dose
  • Hepatic metabolism
  • Greater incidence of rash
  • 2x as expensive as other 2nd gen agents
254
Q

these antibiotics can cause tendon rupture

A

fluoroquinolones like ciprofloxacin

255
Q

Antifolate Drugs Mechanism of action

A

Sequential blockade of DNA synth pathway

256
Q

Trimethoprim-Sulfamethoxazole (Bactrim)

A
  • Antifolate
  • Sulfamethoxazole is only oral sulfonamide still used as an antibacterial agent
  • Only available in combination w/trimethoprim (TMP-SMX)
  • For maximal synergy, dosed in ratio 5 SMX :: 1 TMP
257
Q

Bacterial Susceptibility to Trimethoprim-Sulfamethoxazole

A
  • Bactericidal activity against most gram(+)s and gram(-)s incl CA-MRSA
  • Active against nocardia, Pneumocystis jiroveci,
  • No activity against enetrococci, atypical bacteria, anaerobic bacteria, or Pseudomonas aeruginosa
258
Q

Uses for Trimethoprim-Sulfamethoxazole

A
  • Primary drug for UTIs
  • 2ary drug for upper and lower respiratory tract infections, sepsis, meningitis, travelers diarrhea, typhoid, cholera
259
Q

Pharmacokinetics of Trimethoprim-Sulfamethoxazole

A
  • Can be given both oral and IV
  • Well distributed in tissues including CSF
  • 50% excreted by kidneys
  • T½ = 12 hrs, so can be dosed bid
260
Q

Important adverse reactions to Trimethoprim-Sulfamethoxazole

A
  • Hypersensitivity rxn to SMX – can use TMP alone for UTIs
  • Severe hypersensitivity reactions include exfoliative dermatitis and Stevens-Johnson syndrome
  • High doses for P. jiroveci infections in AIDS: can cause thrombocytopenia, neutropenia, high incidence of allergic reactions, hyperkalemia
261
Q

Important drug interactions for Trimethoprim-Sulfamethoxazole

A

Can increase serum levels and toxicity of warfain, phenytoin, and oral sulfonylureas (for diabetes)

262
Q

Metronidazole (Flagyl)

A
  • antibacterial and antiprotozoal
  • Nitroimidazole that is readily taken up only by anaerobics, then reduced to toxic metabolite
    • Disrupts DNA helix only in anaerobics
  • Best single agent to treat anaerobic infections, incl intra-abdominal infections and C. difficile colitis
  • Available oral and IV
  • Avoid alcohol while taking: disulfiram-like effect
263
Q

Best single agent to treat anaerobic infections

A

Metronidazole

264
Q

FDA Categories for Drug Use in Pregnancy

A
  • CatA – controlled trials show no risk to human fetus
  • CatB – animal studies do not indicate risk, or animal studies indicate risk but controlled trials in pregnant women do not
  • CatC – no available studies or animal studies indicate risk but no controlled trials in women
  • CatD – positive evidence of fetal risk but may be situations where benefit outweighs risk
  • CatX – definite fetal risk clearly outweighs benefit
265
Q

Examples of Category B antibiotics

A
  • β-lactams
  • Azithromycin
  • Clindamycin
  • Metronidazole
266
Q

Examples of Category C antibiotics

A
  • Clarithromycin
  • Fluroquinolones
  • TMP-SMX (1st & 2nd)
  • Nitrofurantoin (1st & 2nd)
  • Vancomycin
267
Q

Examples of Category D antibiotics

A
  • Aminoglycosides
  • Tetracyclines
  • TMP-SMX (3rd)
  • Nitrofurantoin (3rd)

M2 - Pharm (10 decks)

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