Penicillins/Beta-Lactams

Deck 1

What is the mechanism of action of penicillin antibiotics?

Penicillins are beta-lactam antibiotics that inhibit bacterial cell-wall synthesis

They bind to penicillin-binding proteins that interfere with peptidoglycan cross-linking, weakening the cell and causing bacterial death

They are bactericidal

What are the major penicillin medications you should recognize?

Penicillin G

Penicillin V

Amoxicillin

Ampicillin

Nafcillin

Oxacillin

Piperacillin

Amoxicillin/clavulanate (Augmentin)

Ampicillin/sulbactam (Unasyn)

What is penicillin G primarily used to treat?

Serious infections caused by susceptible organisms. A particularly important indication is syphilis

What is penicillin V primarily used to treat?

Susceptible bacterial infections, especially streptococcal infections such as strep throat

What is amoxicillin commonly used to treat?

Susceptible respiratory, ENT, skin, urinary, and other bacterial infections

It is also used in combination regimens for H. pylori

What is ampicillin commonly used to treat?

Susceptible respiratory, GI, GU, and systemic bacterial infections

IV ampicillin may be used for more serious infections

What is the mechanism of action of amoxicillin?

Amoxicillin inhibits bacterial cell-wall synthesis, making it bactericidal against susceptible organisms

What is the major reason clavulanic acid is combined with amoxicillin?

Clavulanic acid inhibits beta-lactamase enzymes, protecting amoxicillin from being destroyed by certain resistant bacteria

What is Augmentin?

Amoxicillin + clavulanic acid

Amoxicillin = antibacterial drug

Clavulanate = beta-lactamase inhibitor

What is Unasyn?

Ampicillin + sulbactam

Ampicillin = antibacterial drug

Sulbactam = beta-lactamase inhibitor

What is the purpose of sulbactam?

It inhibits certain beta-lactamase enzymes, allowing ampicillin to remain effective against bacteria that produce those enzymes

What is beta-lactamase?

A bacterial enzyme that can destroy the beta-lactam portion of certain antibiotics, making the antibiotic ineffective

What is the most important serious adverse effect of penicillins?

Hypersensitivity reactions, including potentially life-threatening anaphylaxis

What should the nurse assess before administering a penicillin?

Ask about:

Previous penicillin allergy

Allergy to other beta-lactams

What symptoms occured

How quickly the reaction occured

Whether the reaction required emergency treatment

A vague history ode to “allergy” should be clarified rather than simply ignored

What are signs of a mild hypersensitivity reaction to penicillin?

Rash, itching, or urticaria (hives)

The patient should be assessed because an allergic reaction can potentially progress

What are signs of anaphylaxis after receiving a penicillin?

Wheezing

Bronchospasm

Difficulty breathing

Throat/tongue/facial swelling

Angioedema

Hives

Hypotension

Tachycardia

Shock

A patient develops wheezing, facial swelling, and hypotension after receiving IV penicillin. What is the priority?

Stop the medication and treat as anaphylaxis

The priority medication is IM epinephrine, along with airway, breathing, and circulatory support and emergency assistance

What is cross-sensitivity between penicillins and cephalosporins?

Because both are beta-lactam antibiotics with related structures, some patients with a penicillin allergy may also react to certain cephalosporins

The risk varies based on the specific drugs and the nature of the previous reaction

What are common adverse effects of penicillins?

Nausea

Vomiting

Diarrhea

Abdominal discomfort

Rash

Serious concerns include anaphylaxis, severe skin reactions, and C. difficile-associated diarrhea

A patient taking amoxicillin develops frequent watery diarrhea. What should the nurse suspect?

C. difficile infection, particularly if the diarrhea is severe or persistent

Antibiotics can disrupt normal intestinal flora and allow C. difficile to proliferate

What are common adverse effects of amoxicillin?

Nausea, vomiting, diarrhea, abdominal discomfort, and rash

Serious reactions include hypersensitivity/anaphylaxis and C. difficile infection

What should a patient taking amoxicillin report immediately?

Difficulty breathing, facial/throat swelling, severe rash, or signs of severe allergic reaction

Severe or persistent watery/bloody diarrhea should also be reported

What is an important teaching point for patients taking amoxicillin?

Take it exactly as prescribed and at every spaced intervals when possible

Do not share of save antibiotics

Report significant allergic reactions or severe diarrhea

What is an important adverse effect associated with amoxicillin/clavulanate (Augmentin)?

GI upset, especially diarrhea

It can also cause hepatic injury, including cholestatic liver problems

Why does Augmentin cause more GI upset than amoxicillin alone in some patients?

The addition of clavulanate can increase GI adverse effects, particularly diarrhea

What should the nurse monitor in a patient receiving prolonged penicillin therapy?

Depending on the drug and clinical situation:

Renal function

Liver funciton

CBC

Signs of superinfection

Signs of hypersensitivity

Therapeutic response

What is nafcillin?

A penicillinase-resistant penicillin used primarily for susceptible MSSA (methicillin-sensitive Staphylococcus aureus) infections

What is oxacillin?

Another penicillinase-resistant penicillin used for susceptible MSSA and other susceptible staphylococcal infections

Why would nafcillin or oxacillin be chosen instead of ordinary penicillin for MSSA?

Some strains of S. aureus produce penicillinase, which destroys ordinary penicillin

Nafcillin and oxacillin resist this enzyme

What is piperacillin?

An extended-spectrum penicillin with activity against many gram-negative organisms, including Pseudomonas aeuginosa

What combination is commonly used with piperacillin?

Piperacillin/tazobactam (Zosyn)

What does tazobactam do in piperacillin/tazobactam?

It is a beta-lactase inhibitor that protects piperacillin from certain beta-lactamase enzymes

What important organism should you associate with piperacillin/tazobactam?

Pseudomonas aeruginosa

What is a major nursing concern with IV penicillins?

Monitor for immediate hypersensitivity/anaphylaxis, especially after administration

Also monitor IV site and overall therapeutic response

What is the relationship between penicillin allergy and anaphylaxis?

A previous severe immediate hypersensitivity reaction to a penicillin increases concern for a potentially serious reaction with re-exposure

What is the difference between a side effect and an allergic reaction to penicillin?

A side effect is unwanted pharmacologic effect, such as nausea or diarrhea

An allergic reaction involves the immune system and may cause hives, angioedema, bronchospasm, or anaphylaxis

A patient says, “Penicillin makes me nauseated, so I’m allergic.” How should the nurse interpret this?

Nausea alone is generally an adverse effect-intolerance rather than a true allergy

The patient’s reaction should still be documented accurately

What patient teaching is important regarding antibiotic-associated diarrhea?

Mild diarrhea can occur, but severe, persistent, watery, or bloody diarrhea should be reported because it may indicate C. difficile infection

Why should patients not share leftover penicillin with another person who has similar symptoms?

The other person may have a different infection that requires a different treatment-or a viral infection that does not require antibiotics

Sharing promotes inappropriate therapy and resistance and can cause adverse reactions

What are the highest-yield penicillin drug combinations to recognize on an exam?

Amoxicillin + clavulanate = Augmentin

Ampicillin + sulbactam = Unasyn

Piperacillin + tzobactam = Zosyn

In each combination, the second drug is a beta-lactamase inhibitor

What is the main therapeutic effect you expect from a penicillin?

Resolution of the bacterial infection:

Decreased fever, pain, inflammation, drainage, and other infection symptoms, with improvement in relevant laboratory findings

What should the nurse assess before giving a beta-lactam antibiotic to a patient with a reported allergy?

Determine:

Which drug caused the reaction

What symptoms occured

How quickly symptoms appeared

Whether there was respiratory or cardiovascular involvement

Whether emergency treatment was required

Why is the type of previous allergic reaction important?

A history of anaphylaxis, angioedema, or respiratory compromise indicates a much more serious immediate hypersensitivity reaction than an isolated, non-specific side effect

What should a nurse do if a patient has a documented severe penicillin allergy and a new penicillin order appears?

Do not administer the medication without clarification

Verify the allergy and contact the prescriber/pharmacist for an appropriate alternative

What is the most important emergency medication for severe beta-lactam anaphylaxis?

Epinephrine, typically administered IM in the outer thigh for anaphylaxis

Why should airway and breathing be assessed immediately during anaphylaxis?

Anaphylaxis can rapidly cause airway edema and bronchospasm, leading to respiratory failure

What is a possible consequence of prolonged broad-spectrum penicillin therapy?

Superinfection, because normal flora may be disrupted, allowing organisms such as Candida or C. difficile to overgrow

What symptoms suggest a Candida superinfection during antibiotic therapy?

Oral thrush, white plaques in the mouth, vaginal itching/discharge, or other fungal symptoms

Why can antibiotics cause Candida infections?

Antibiotics can eliminate normal bacterial flora that normally help keep candida growth under control

What should a patient taking antibiotics know about alcohol?

Ordinary penicillins do not have the classic disulfiram-like alcohol interaction associated with metronidazole

Patients should follow medication-specific instructions and avoid alcohol if it worsens GI symptoms or is otherwise contraindicated

What is an. important concern with penicillins in patients with renal impairment?

Some penicillins are substantially eliminated by the kidneys, so renal function and dosing may need to be monitored/adjusted depending on the specific drug

Why might kidney function be monitored during antibiotic therapy?

Reduced renal function can cause certain medications or metabolites to accumulate, increasing risk of toxicity

What is the relationship between culture results and penicillin therapy?

Cultures can identify the organism and susceptibility pattern, allowing therapy to be narrowed or changed to the most appropriate antibiotic

If a culture shows that the bacteria are resistant to the prescribed penicillin, what should the nurse anticipate?

The provider will likely change the antibiotic to one which the organism is susceptible

Why is it undesirable to keep a patient on an unnecessarily broad-spectrum antibiotic?

It can increase adverse effects, disruption of normal flora, superinfection, and antimicrobial resistance

What is a major teaching point for patients receiving antibiotics for infection?

Take doses on schedule and follow the prescribed duration/instructions

Do not independently stop, extend, or restart therapy

What should a patient do if symptoms improve after only a few doses of an antibiotic?

Continue the medication according to the prescribed treatment plan rather than independently stopping because they feel better

What should the nurse teach a patient about signs that the antibiotic is working?

The patient should expect gradual improvement in the infection, such as less fever, pain, swelling, redness, drainage, or other infection symptoms

What is one important difference between penicillin G and penicillin V?

Penicillin G is commonly administered parenterally, while penicillin V is an oral formulation used for susceptible infections

A patient receiving a penicillin develops hives but has normal blood pressure and no breathing difficulty. What is the priority?

Stop/hold the medication and assess the patient and notify the provider because hives can indicate an allergic reaction

Monitor closely for progression to anaphylaxis

Which penicillin is especially associated with treatment of syphilis?

Penicillin G (specifically berzathine penicillin G for most uncomplicated syphilis treatment)

What is berzathine penicillin G?

A long-acting IM formulation of penicillin G used for certain infections, most notably syphilis

Why is berzathine penicillin G given IM rather than IV?

Its formulation is designed for slow absorption and prolonged exposure

It should not be administered IV

What is amoxicillin’s relationship to ampicillin?

Both are aminopenicillins with similar mechanisms and activity

Amoxicillin has better oral absorption and is commonly used orally

What is a common indication for amoxicillin in combination with other drugs?

H. pylori eradication as part of combination therapy with other medications

Why are multiple antibiotics sometimes used together to treat an infection?

Combination therapy may provide broader coverage, treat polymicrobial infections, prevent resistance in certain situations, or provide synergistic activity against specific organisms

What does synergistic antibiotic therapy mean?

Two drugs work together so that their combined antibacterial effect is greater than the effect expected from either drug along

Does combining antibiotics always improve treatment?

No

Unnecessary combinations can increase toxicity, drug interactions, cost, disruption of normal flora, and resistance

What is piperacillin/tazobactam especially useful for?

Serious infections requiring broad coverage, including infections involving pseudomonas and certain polymicrobial infections

What is a major nursing concern with piperacillin/tazobactam?

Assess for beta-lactam allergy, monitor renal function when appropriate, assess the infection response, and monitor for diarrhea/superinfection and other adverse effects

Why is piperacillin/tazobactam considered broad-spectrum?

It provides activity against a wide range of organisms, including many gram-positive, gram-negative, and anaerobic organisms, with activity against pseudomonas

What is the significance of a patient receiving piperacillin/tazobactam who has a history of severe penicillin anaphylaxis?

This is a major safety concern because piperacillin is a penicillin

The allergy must be addressed before administration

What should the nurse do if a patient develops severe watery diarrhea after several days of piperacillin/tazobactam?

Suspect possible C. difficile infection, notify the provider, and follow appropriate testing and infection-control procedures

What is a superinfection?

An infection that develops because antimicrobial therapy alters normal flora or selects for organisms resistant to the original antibiotic

Which two superinfections should you especially associate with broad-spectrum antibiotics?

Candida overgrowth and C. difficile infection

What patient teaching helps reduce the risk of antimicrobial resistance?

Use antibiotics only when prescribed, take them exactly as directed, don’t share them, don’t use leftovers, and don’t pressure providers for antibiotics when they aren’t indicated

What should a patient do with leftover antibiotics?

Do no save them for future illnesses or give them to someone else

Follow local medication-disposal instructions

Why should patients not skip antibiotic doses?

Inadequate exposure can contribute to treatment failure and selection of resistant organisms

What should the nurse assess to determine whether a penicillin is effectively treating an infection?

Compare baseline and current:

Temperature

WBC count

Pain

Swelling/redness

Drainage

Vital signs

Culture results when available

Patients overall clinical condition

A patient taking amoxicillin says, “My fever is gone, so I stopped taking it yesterday.” What is the best nursing response?

Explain that improvement does not necessarily mean the infection has been completely treatmed

The patient should follow the prescribed treatment plan and contact the prescriber if there are concerns about stopping or adverse effects

What is the most important reason to obtain a detailed allergy history before giving a penicillin?

Penicillins can cause IgE-mediated hypersensitivity and anaphylaxis, which can be rapidly life-threatening

What is the difference between an immediate and delayed hypersensitivity reaction to a penicillin?

Immediate: can occur rapidly and may cause hives, angioedema, bronchospasm, hypotension, and anaphylaxis

Delayed: may appear later, often as a rash or other immune-mediated reaction

What should the nurse do if a patient reports a previous penicillin reaction but cannot remember what happened?

Clarify the reaction if possible:

What symptoms occurred, how soon after the medication, and whether the treatment was required

Do not automatically assume the reaction was or wasn’t a true allergy

What is the priority assessment after giving IV penicillin?

Assess for hypersensitivity, particularly during and shortly after administration, including airway, breathing, skin findings, and blood pressure

Why is IV administration of a beta-lactam potentially more concerning for an immediate reaction?

IV administration provides rapid systemic exposure, so a severe hypersensitivity reaction can develop quickly

What are common GI effects of beta-lactam antibiotics?

Nausea, vomiting, abdominal discomfort, and diarrhea

What makes antibiotic-associated diarrhea particularly concerning?

Frequent, watery, severe, persistent, or bloody diarrhea, especially with abdominal cramping or fever, may indicate C. difficile infection

Why shouldn’t a patient automatically take an antidiarrheal medication for severe diarrhea after antibiotics?

The diarrhea may be caused by C. difficile

Suppressing intestinal motility without evaluation can be inappropriate and potentially harmful

What is a key sign that a patient may be developing a superinfection?

A new infection develops during therapy, such as oral thrush, vaginal candidiasis, or significant new diarrhea

What should the nurse assess if a patient develops oral thrush while taking a broad-spectrum penicillin?

Assess the oral lesions, discomfort, swallowing/nutritional status, and notify the provider because the patient may have a Candida superinfection

Why can broad-spectrum penicillins increase the risk of superinfection?

They affect a larger variety of bacteria, including normal protective flora, allowing opportunistic organisms to overgrow

What does “spectrum of activity” mean?

The range of microorganisms against which an antimicrobial is effective

Why would a provider initially use a broad-spectrum antibiotic?

When the causative organism is unknown and prompt treatment is needed against the likely pathogens

What should happen to antibiotic therapy after culture and susceptibility results become available?

When clinically appropriate, therapy should be narrowed or changed to the most targeted effective antibiotic

What does “culture and sensitivity” tell the healthcare team?

The culture identifies the microorganism, while susceptibility testing helps determine which antimicrobial drugs are likely to be effective

Patient is receiving empiric piperacillin/tazobactam. The culture later identifies a susceptible organism that can be treated with a narrow-spectrum drug. Why might the provider change therapy?

To reduce unnecessary broad-spectrum exposure and decrease the risks of resistance, superinfection, and adverse effects

What is the significance of renal function when administering many beta-lactam antibiotics?

Many beta-lactams are substantially eliminated by the kidneys

Renal impairment may require dose adjustment and increases the risk of drug accumulation

What should the nurse do if a patient’s renal function worsens while receiving a renal cleared beta-lactam?

Notify the appropriate provider/pharmacist and anticipate dose or interval adjustment based on the specific drug and renal function

What are the most important patient-teaching points for oral penicillin therapy?

Take exactly as prescribed

Take doses at the appropriate intervals

Don’t share or save medication

Report severe allergic symptoms

Report severe/persistent diarrhea

Complete/follow the prescribed treatment plan

Understand that antibiotics don’t treat viral infection

A patient taking amoxicillin develops facial swelling, wheezing, and a blood pressure of 82/48 mmHg. What should the nurse recognize and do?

This is anaphylaxis

Stop the antibiotic, call for emergency assistance, administer IM epinephrine promptly, and support airway, breathing, and circulation