(EDAPT WEEK 7)
INFECTION
Pharmacology For Nursing Practice
,PHARM WEEK 7 EDAPT INFECTION
Antibiotics: What They Do
Antibiotics are classified into broad categories based on their chemical
structure and activities (potency, toxicity, mechanism of action, etc.).
Antibiotics kill bacteria in four basic ways:
1. Stopping bacterial cell wall creation
2. Stopping bacteria from producing proteins that harm or replicate
3. Stopping bacteria from replicating deoxynucleic acid (DNA) or
ribonucleic acid (RNA); also known as the blueprints for proteins
4. Disrupting or stopping cell metabolism
Bacteria Identification
Bacteria are identified by whether they are gram-positive or gram-negative.
They are also identified by their bacterial wall. Gram staining (the coloring
seen on a slide plate) determines what type of cell wall a bacteria has and
what type of antibiotic would be most successful in destroying the bacterial
cell wall.
A culture grown from the source of infection can also identify bacteria based
on its shape and characteristics from the sample culture.
Treatment with antibiotics often starts with a broad-spectrum antibiotic
based on which infectious agents commonly cause the client's
condition. Once laboratory testing has confirmed the infecting organism, the
antibiotic will be changed to one that is more specific for that bacteria.
Resistance
Bacteria are tested for how much “resistance” they may have against a
particular bacteria. This resistance is measured in a test called a sensitivity
test.
In this test, an antibiotic is added to a plate with the bacteria in question on
it. The measurement of how much bacteria is killed around the antibiotic
describes the bacteria’s susceptibility to that antibiotic. A resistant bacteria
may not be significantly damaged by the antibiotic and, therefore, the
antibiotic should not be given.
,Mixing and Beta-Lactamase
Some bacteria make an enzyme called beta-lactamase which can destroy
penicillin. These bacteria are penicillin-resistant. Some antibiotics can be
paired with other chemicals that destroy beta-lactamase.
For example, amoxicillin (a form of penicillin) is mixed with clavulanic acid
(destroys beta-lactamase) to destroy the penicillin-resistant bacteria in a
formulation named amoxicillin/clavulanate potassium.
Distribution
For antibiotics to work, they need to enter the body, get to the site where
bacteria is present, and destroy the bacteria. How the antibiotics get to this
point is determined by the administration route (e.g., oral, injectable, topical)
and how easy it is to get to the site where the bacteria is present.
For example, if the infection is on the skin, a topical antibiotic may get to the
area faster than one taken by mouth.
Antibiotic allergies are common
Important to check allergy band or chart to ensure there are no known
antibiotic allergies.
Antibiotics can interact with food
It is important to review possible food or medication interaction with
patient.
Antibiotic resistance can occur if not used for full course
Important to finish course of antibiotics to reduce possible resistance
being created.
Antibiotics and expectation for many provider visits
Important to use antibiotics wisely and promote safe use to reduce
resistance.
Check for kidney or liver dysfunction before starting
Some antibiotics hurt the kidneys or liver. Dosages are often adjusted
in kidney and liver failure. Important to monitor kidney and liver
function before starting.
, Antibiotic Classes
Each antibiotic class has a way of destroying or reducing the replication of
bacteria:
Reducing the replication means they are bacteriostatic.
Destroying the bacteria makes the antibiotic bactericidal.
These antibiotic classes also may include subclasses and combinations.
Natural Penicillin
Mechanism of Action (MOA): Binds to proteins that inhibit
peptidoglycan interfering with bacterial wall synthesis
Drug Example: penicillin VK
Penicillinase-Resistance Penicillin
Mechanism of Action (MOA): Interferes with bacterial wall synthesis
and protects against penicillinase (a penicillin-destroying enzyme
produced by some bacteria)
Drug Example: nafcillin
Cephalosporins
There are 5 different generations of cephalosporins.
Mechanism of Action (MOA): Inhibits peptidoglycan, interfering with
bacterial wall synthesis
Drug Examples:
cefazolin – first generation
ceftaroline – fifth generation