Ppt chapter 39

Chapter 39
Antibiotics Affecting the
Bacterial Cell Wall
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Physiology
• Bacteria are surrounded by a rigid cell wall that is
responsible for maintaining the integrity of the internal
cellular environment.
• The interior of the cell has a high osmotic pressure.
• If the bacterial cell wall is not intact, the internal osmotic
pressure draws fluid into the cell until it bursts.
• Even when the cell wall is breached by an antibiotic,
bacterial death may not occur because of bacterial
resistance.

Physiology (cont.)
• Drugs that affect the bacterial cell wall must be able to
penetrate the cell wall to bind to molecular targets on the
cell.
• Beta-lactamases are enzymes that disrupt the beta-lactam
ring.
• This mechanism inactivates beta-lactam drugs.

Cytoplasmic Membrane

Pathophysiology
• Bacteria may cause infections in any body organ,
structure, or fluid.
• In addition to the original bacterial infection, the loss of
certain “good” bacteria may result in a superinfection.

Penicillins
• Penicillins were the first antibiotics introduced for clinical
use.
• Alexander Fleming derived them from Penicillium molds
in 1929.
• Subsequent versions of penicillin have been developed to
decrease the adverse effects of the drug and to modify
its ability to act on resistant bacteria.
• Penicillins are also called beta-lactam antibiotics because
their chemical structure contains a beta-lactam ring that
is essential for antibacterial activity.
• Penicillins are classified as narrow spectrum.
• Prototype drug: penicillin G

Penicillin G: Core Drug Knowledge
• Pharmacotherapeutics
– Infections caused by susceptible gram-positive
bacteria
• Pharmacokinetics
– Administered: IM or IV. Highly protein bound.
Excreted: kidneys.
• Pharmacodynamics
– Inhibits the third and final stage of bacterial cell wall
synthesis

Penicillin G: Core Drug Knowledge (cont.)
• Contraindications and precautions
– Known allergies to penicillin, cephalosporins, or
imipenem
• Adverse effects
– GI upset, rash, fever, wheezing, possibly anaphylaxis
and death
• Drug interactions
– Tetracyclines, aminoglycosides, and probenecid

Penicillin G: Core Patient Variables
• Health status
– Assess health history and allergies.
• Life span and gender
– The drug counteracts the effects of an oral
contraceptive.
• Lifestyle, diet, and habits
– Administer the drug around the clock.
• Environment
– Assess the environment where the drug will be given.

Penicillin G: Nursing Diagnoses and
Outcomes
• Risk for Injury related to drug-related allergic reactions
– Desired outcome: The patient will recognize
symptoms of allergy and contact the prescriber
immediately to minimize ill effects.
• Imbalanced Nutrition: Less than Body Requirements
related to drug-induced GI effects, such as diarrhea, GI
upset, altered taste sensation, or superinfection
– Desired outcome: The patient will maintain
consistent body weight and consult the prescriber
about persistent adverse effects that affect
nutritional status.

Penicillin G: Nursing Diagnoses and
Outcomes (cont.)
• Diarrhea related to drug therapy
– Desired outcome: The patient will avoid
dehydration, maintain fluid intake, and contact the
prescriber about persistent diarrhea.
• Risk for Infection related to overgrowth of nonsusceptible
organisms
– Desired outcome: The patient will report signs of
superinfection to the prescriber.

Penicillin G: Planning and Interventions
• Maximizing therapeutic effects
– Review culture and sensitivity reports to make sure
that penicillin G is appropriate for the patient.
– Optimally, drug therapy should continue for at least 7
to 10 days.
• Minimizing adverse effects
– Provide small, frequent meals; mouth care; and ice
chips.
– Notify the prescriber if a substantial change develops
in the intake-to-output ratio.

Penicillin G: Teaching, Assessment, and
Evaluations
• Patient and family education
– Stress the importance of completing the full course of
antibiotics.
– Emphasize the need to take penicillin G exactly as
prescribed at evenly spaced intervals.
• Ongoing assessment and evaluation
– Monitor for signs of allergic reaction and for
resolution of the presenting symptoms of infection.

Question
• Penicillin G is given via which of the following route(s)?
– A. Oral
– B. IM
– C. IV
– D. Both B and C
– E. All of the above

Answer
• D. Both B and C
• Rationale: Penicillin G is absorbed rapidly from the
gastrointestinal (GI) tract but is unstable in gastric
acid. Because of this instability, penicillin G is not
given orally.

Cephalosporins
• The cephalosporins were first introduced in the 1960s.
• They are similar to the penicillins in structure and in
activity and are also considered beta-lactam antibiotics.
• Four generations of cephalosporins have been
introduced, each group with its own spectrum of activity.
• Selecting an antibiotic from this class depends on the
sensitivity of the involved organism.
• The major differences between the generations include
their activity against gram-negative bacteria, their
resistance to beta-lactamases, and their ability to
distribute into cerebrospinal fluid.
• Prototype drug: cefazolin (Ancef, Kefzol)

Cefazolin: Core Drug Knowledge
– Treats many kinds of infections
– Administered: IM. Peak: 1.5 to 2 hours.
– Binds with PBPs, which disrupts bacterial cell wall
synthesis

Cefazolin: Core Drug Knowledge (cont.)
– Known allergy to cephalosporins
• Adverse effects
– Maculopapular rash, GI symptoms, headache,
dizziness, lethargy, paresthesias, and nephrotoxicity
– Aminoglycosides

Cefazolin: Core Patient Variables
• Health status
– Assess history and allergies.
– Assess for pregnancy and lactation.
• Lifestyle, diet, and habits
– Assess lifestyle to ensure ability to comply with
therapy.
• Environment

Cefazolin: Nursing Diagnoses and
Outcomes
• Diarrhea related to drug effects
– Desired outcome: The patient will avoid dehydration,
maintain fluid intake, and contact the prescriber if
diarrhea persists.
• Imbalanced Nutrition: More or Less than Body Requirements
related to GI effects, alteration in taste, superinfections
– Desired outcome: The patient will maintain body weight
and contact the prescriber if persistent adverse effects
alter nutritional status.
organisms

Cefazolin: Planning and Interventions
– Review culture and sensitivity tests to evaluate the
efficacy of treatment.
– Oral suspensions should be kept in the refrigerator.
– Cefazolin may be taken with food or fluids to
decrease GI distress.
– Evaluate the patient for CNS effects and use safety
precautions.

Cefazolin: Teaching, Assessment, and
Evaluations
– Because cefazolin and the other cephalosporins are
similar to penicillins, follow the same guidelines for
providing patient and family education to a patient
receiving penicillin.
– Monitor the patient for any signs of superinfection
and notify the prescriber immediately to arrange for
treatment if superinfection does occur.

Question
• First-generation cephalosporins are effective at treating
gram-negative infections.
– A. True
– B. False

Answer
• B. False
• Rationale: The first-generation cephalosporins have
little activity against gram-negative bacteria.

Vancomycin
• Vancomycin (Vancocin) is a complex and unusual tricyclic
glycopeptide antibiotic.
• It is the only drug in its class.
• The use of vancomycin is limited by its ability to produce
toxic effects.
• Vancomycin is used only when other antibiotics fail to
resolve an infection.
• It has been touted as being able to eradicate most gram-positive
pathogens.

Vancomycin: Core Drug Knowledge
– Treating bacterial septicemia, endocarditis, bone and
joint infections
– Administered: oral or IV. Excreted: kidneys and
feces. Peak: 1 hour.
– Inhibits cell wall synthesis by altering the cell’s
permeability

Vancomycin: Core Drug Knowledge (cont.)
– Hypersensitivity and pregnancy
• Adverse effects
– Ototoxicity and nephrotoxicity
– Antihyperlipidemic drugs and nondepolarizing muscle
relaxants

Vancomycin: Core Patient Variables
• Health status
– Assess for contraindications to therapy.
– Assess pregnancy and lactation status.
• Environment

Vancomycin: Nursing Diagnoses and
Outcomes
• Risk for Injury related to drug-induced histamine-release
reactions
– Desired outcome: The patient will experience no
preventable reaction related to vancomycin.
• Disturbed Sensory Perception (auditory) related to drug-induced
ototoxicity
– Desired outcome: The patient will report any
unusual auditory sensations and have periodic
audiograms to detect early ototoxicity.

Vancomycin: Nursing Diagnoses and
Outcomes (cont.)
• Excess Fluid Volume related to nephrotoxicity from drug
therapy
– Desired outcome: The patient will remain
normovolemic throughout therapy.
organisms

Vancomycin: Planning and Interventions
– Ensure that the patient receives the full course of
vancomycin as prescribed.
– Culture and sensitivity results should be monitored.
– Administer vancomycin over at least 60 minutes.
– Assess the IV site frequently for signs of phlebitis.

Vancomycin: Teaching, Assessment, and
Evaluations
– Advise the patient of the importance of completing
therapy.
– Explain the potential adverse effects and need for
periodic blood monitoring.
– Monitor for signs of ototoxicity.
– For patients receiving long-term or high-dose
therapy, coordinate periodic audiometric testing and
lab tests.

Question
• The oral form of vancomycin is used to treat
– A. Gastric ulcers
– B. Prostatitis
– C. Rupture of diverticulum
– D. Pseudomembranous colitis

Answer
• D. Pseudomembranous colitis
• Rationale: Oral administration is used in treating
some GI infections, such as pseudomembranous
colitis.

Ppt chapter 39

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