Transcript Antimicrobial Therapy Week 5 & 6

Chapter 7
Antimicrobial Agents
Anti-infective Therapy

Modern age


Discovery of sulfanilamide in 1936
Commercial introduction of penicillin in 1941
7-2
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Antimicrobial Therapy


Original antimicrobials: derived from
microorganisms
Newer agents: chemically synthesized
7-3
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Factors Leading to Infection
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Age: young and elderly
Increased exposure to pathogenic
organisms
Disruption of the normal barriers
Inadequate immunological defenses
Impaired circulation
Poor nutritional status
7-4
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Sources of Infection



Bacteria
Fungi
Viruses
7-5
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Administering Antimicrobial
Agents

Consider the following:


7-6
Location of the infecting organism in the
body
Status of the client’s organ function
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(continued)
Administering Antimicrobial
Agents

Consider the following:



Age of the client
Pregnancy and/or lactation
Likelihood of developing organisms resistant
to the antimicrobial agent
7-7
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Overuse

Overuse of antimicrobial agents can
lead to the development of severely
resistant organisms.

Promoted the development of organisms
that are not affected by any of the available
therapies
7-8
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Resistant Organisms



MRSA/VRSA: methicillin/vancomycinresistant Staphylococcus aureus
VRE: vancomycin-resistant
Enterococcus
ORSA: oxacillin-resistant
Staphylococcus aureus
7-9
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Antimicrobial Therapy


Prevent infections.
Use Universal Precautions.
7 - 10
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Classifications

Antimicrobial agents are classified based
on the following factors:

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Bactericidal or bacteriostatic
Site of action
Narrow or broad spectrum
Adverse effects
7 - 11
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Antimicrobial Classes
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Sulfonamides
Penicillins
Cephalosporins
Tetracyclines
Macrolides
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
Aminoglycosides
Fluoroquinolones
Carbapenem
Ketolides
7 - 12
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Sulfonimides

First group of antibiotics

General action


Bacteriostatic effect
Inhibit para-aminobenzoic acid (PABA)
•

PABA is essential for bacterial growth
Broad spectrum
7 - 13
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Sulfonamides: Therapeutic Uses



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Treatment of urinary tract infections
Otitis media
Certain vaginal infections
Some respiratory infections
7 - 14
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Sulfonamides: Adverse Effects



Hypersensitivity
Renal dysfunction
Hematological changes
7 - 15
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Sulfonamides: Nursing
Implications



Consume at least 1 liter of fluid/day
Avoid sunlight and tanning beds
Reduce the effectiveness of oral
contraceptives
7 - 16
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Sulfonamide Combinations

Sulfonamides also combined with:

Antimicrobials, diuretics, oral
hypoglycemics, and carbonic anhydrase
inhibitors
7 - 17
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Penicillins

Part of a large group of chemically
related antibiotics


Derived from fungus or mold
Cephalosporins currently used instead of
the penicillins
7 - 18
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Penicillins: Action

Inhibit synthesis of the bacterial cell wall


Most effective on newly forming and actively
growing cell walls
Some of the penicillins are rapidly destroyed
in the stomach.

7 - 19
Given IM or IV
(continues)
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(continued)
Action of penicillin on bacteria (from Medicines and
You, U.S. Department of Health and Human Services)
7 - 20
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Resistance to Penicillins

Frequent early use of penicillin caused:

Penicillinase


The bacteria to produce penicillin-destroying
enzymes
Potassium clavulanate inhibits penicillinase:
combined with penicillin
7 - 21
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Penicillins: Therapeutic Uses

Prevention and treatment of gram (+)
bacterial infections:

Enterococcus, Streptococcus, and
Staphylococcus bacteria
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Penicillins: Adverse Effects




Hypersensitivity
Gastrointestinal symptoms
Neurotoxicity
Renal dysfunction
7 - 23
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Cephalosporins


Chemically and pharmacologically
related to penicillins
Action: prevent bacterial cell wall
synthesis
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Cephalosporins: Action

Either bactericidal or bacteriostatic;
depends on:

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Susceptibility of organism
Dose of drug
Tissue concentration
Rate of bacteria multiplication
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Classes of Cephalosporin

Include several generations:
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First: good gram-positive coverage
Second: good gram-positive coverage;
some gram-negative coverage
Third: less gram-positive coverage; more
gram-negative coverage
Fourth: good gram-negative coverage
7 - 26
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Treatment with Cephalosporins

Treat infections of:
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Skin
Bone
Heart
Blood
Respiratory tract
Gastrointestinal tract
Urinary tract
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Cephalosporins: Adverse Effects


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
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Hypersensitivity
Cross-sensitivity reaction to penicillin
Thrombophlebitis (when given IV)
Sterile abscess (when given IM)
Nephrotoxicity
7 - 28
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Tetracyclines



Action: inhibit protein synthesis in the
bacterial cell; bacteriostatic
Broad spectrum
 Bacteria: gram – and gram +
Effective against: protozoa,
Mycoplasma, Rickettsia, Chlamydia,
syphilis, Lyme disease
7 - 29
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Tetracyclines: Nursing
Implications


Bind to Ca2+, Mg2+, and Al3+ ions and
form insoluble complexes
Do not give tetracycline with:

Dairy products, antacids, or iron salts
7 - 30
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Tetracyclines: Toxic Effects


Do not give to children.
Affects tooth development from:


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Fourth month of fetal development to 8
years old
Temporary and permanent discoloration of
developing teeth
Photosensitivity
Superinfection
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Macrolides

Action


Bacteriostatic: inhibits protein synthesis in
the bacterial cell
Primarily used for respiratory,
gastrointestinal, urinary, skin, and soft
tissue infections
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Treatment with Macrolides

Treat both gram + and some gram –
organisms


Erythromycin: preferred (pertussis)
Primarily metabolized by the liver and
excreted in the urine
7 - 33
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Macrolides: Adverse Effects




Hypersensitivity
Gastrointestinal effects
Hepatotoxicity
Jaundice
7 - 34
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Aminoglycosides

Poor oral absorption


Given intravenously, not orally
Action



Bactericidal: inhibit cell wall protein
synthesis
Effective: gram – and some gram +
Narrow therapeutic range

Potent antibiotics with serious toxicities!
7 - 35
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Aminoglycosides: Toxicities

Serious toxicities: caution



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Nephrotoxicity
Ototoxicity
Block neuromuscular action, which can
lead to respiratory paralysis
Monitor drug levels, both peak and
trough
7 - 36
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Fluoroquinolones


First oral antibiotics effective against
gram-negative bacteria
Excellent oral absorption
7 - 37
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Fluoroquinolones: Action


Bactericidal: alter DNA
Broad spectrum: effective against gramnegative organisms and some grampositive organisms
7 - 38
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Treatment with Fluoroquinolones

Treat infections of:






Lower respiratory tract
Bone and joint
Infectious diarrhea
Urinary tract
Skin
Sexually transmitted diseases
7 - 39
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Fluoroquinolones: Nursing
Implications

Consume at least 1 liter of fluid/day
7 - 40
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Carbapenems



Action: Inhibit synthesis of the bacterial
cell wall
Broad spectrum
Effective:



Gram negative
Gram positive
Treat community acquired pneumonia
7 - 41
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Carbapenems: Nursing
Considerations



Given intravenously and intramuscularly
Cross-sensitivity to penicillins
Advantage

Given once every 24 hours
7 - 42
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Carbapenems: Adverse Effects



Hypersensitivity
Diarrhea
Local reactions at intramuscular and
intravenous sites
7 - 43
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Ketolides


FDA approved in 2004
New class

Developed from macrolides


Semisynthetic
Treat macrolide-resistant strep pneumonia
7 - 44
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Ketolides: Adverse Effects



Hypersensitivity
Headache
Diarrhea
7 - 45
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Urinary Tract
Anti-infectives

Trimethoprim


7 - 46
Most common
Blocks the synthesis of folate in bacteria,
thus inhibiting formation of nucleic acid and
protein
(continues)
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(continued)

Urinary Tract
Anti-infectives
Others


Methenamine products: produces local
bactericidal effect
Nitrofurantoin: stops CHO metabolism

Produces yellow-brown urine
7 - 47
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Antimicrobial Therapy


General nursing implications
Instructions take as prescribed:


Length of time: do not stop before
antimicrobials are gone
Assess for signs and symptoms of
returning infection
7 - 48
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Antimicrobials: Nursing
Implications

Obtain cultures from appropriate sites
before beginning therapy.
7 - 49
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Antitubercular Agents

Tuberculosis (TB)
Mycobacterium tuberculosis




An aerobic bacillus
Requires oxygen to survive
Antitubercular agents treat all forms of
Mycobacterium
7 - 50
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Tuberculosis


TB close to eradication; new resistant
strain developed in immunocompromised
individuals and immigrants to the U.S.
Drug therapy is given in two forms:


Preventive therapy
Active therapy
7 - 51
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TB: Preventive Therapy

Preferred agent


INH (Isoniazid)
Known as chemoprophylaxis




Safest
Low cost
Action: tuberculostatic and tuberculocidal
Treatment: 18 months to 2 years
7 - 52
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Isoniazid

INH


Action: inhibits the synthesis of mycolic acid
Adverse effects of INH




Hepatotoxicity: jaundice
Peripheral neuritis
Nausea
Skin rashes
7 - 53
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Multiple Drug Therapy


Required: combination of two or three
agents
Helps prevent development of resistant
strains
7 - 54
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Antitubercular Therapy

Effectiveness depends on:





Where
Strain
Effective drug combination
Sufficient duration
Effective drug compliance
7 - 55
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Antitubercular Agents:
Nursing Implications




Client education is critical.
Therapy may last for up to 24 months.
Take medications exactly as ordered.
Emphasize the importance of strict
compliance.
7 - 56
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Antitubercular Agents:
Nursing Implications



Do not consume alcohol.
Diabetic: monitor blood glucose levels
INH and rifampin:

Oral contraceptives ineffective
7 - 57
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Lyme Disease

Spirochete Borrelia burgdorferi


Transmitted from a deer tick
Symptoms


Rash
Flulike symptoms, followed by arthritis and
fatigue
7 - 58
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Treatment for Lyme Disease

Oral doxycycline



Adults: 100 mg b.i.d
Length: 10 to 14 days
Adverse effect

Photosensitivity
7 - 59
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Fungi

Contracted



Air
Skin to skin
Due to normal flora being killed off:




Antibiotics
Corticosteroid therapy
Antineoplastic agents
Suppressed immune system
7 - 60
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Mycotic Infections

Three general types



Cutaneous
Subcutaneous
Systemic (can be life threatening)
7 - 61
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Antifungal Agents

Treatment


Antibiotic therapy will not work.
Requires prolonged treatment


Human cell structure resembles fungi cell
structure.
Action

Antifungal agents take advantage of the
slight differences of the cell structures.
7 - 62
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Antifungal Agents: General
Adverse Effects



Topical: irritation and redness
Oral: nausea, vomiting, and diarrhea
May potentiate antihistamines
7 - 63
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Antifungal Agents: Adverse
Effects


IV: hepatotoxicity, renal toxicity, and
phlebitis
IV drugs must be diluted and
administered slowly: amphotericin B
7 - 64
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Antifungal Agents: Nursing
Implications

IV



Monitor vital signs every 15 to 30 minutes.
Monitor input and output.
Monitor urinalysis findings.
7 - 65
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Antiviral Agents

Viruses cause many infectious disorders:




Acute: common cold
Chronic: herpes
Slow growing: AIDS
Available vaccines

Polio, rabies, and smallpox
7 - 66
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Viral Replication


A virus cannot replicate on its own.
It must attach to and enter a host cell.

7 - 67
Uses the host cell’s energy to synthesize
protein: DNA and RNA
(continues)
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(continued)
Life cycle of a virus
7 - 68
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Interferons

Normally, interferons protect the cells
from infecting viruses.


Interferon: continuous research
Recent antifungal agents end in “vir”
7 - 69
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Antiviral Agents: Key
Characteristics

Inhibit viral replication by interfering with:



Viral nucleic acid synthesis and/or regulation
Ability of virus to bind to cells
Interferon: stimulates immune system
7 - 70
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Treatment with Antiviral Agents

Antiviral agents treat:




Influenzae A
Herpes simplex
RSV
AIDS, HIV
7 - 71
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Antiviral Agents: Adverse Effects





Bone marrow suppression
Nephrotoxicity
Hepatotoxicity
Gastrointestinal effects
Central nervous system effects
7 - 72
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Antiviral Agents: Nursing
Implications

Be sure to teach proper application:




7 - 73
Ointments
Aerosol powders
Emphasize handwashing.
Wear gloves for topical application.
(continues)
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(continued)

Usually not a cure


Antiviral Agents: Nursing
Implications
Replications cease: remain in nerve fibers
Therapeutic effects vary


Range from delayed progression of AIDS
and ARC to decrease in flulike symptoms
Frequency of herpes-like flare-ups decrease
7 - 74
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