Ed Beatty Case Study: IM Penicillin G, Renal Insufficiency, Anaphylaxis and Cardiac Arrest (Nursing Answers)

Key pharmacology background

Penicillins are beta-lactam antibiotics that kill bacteria by inhibiting cell wall synthesis. Group A Streptococcus remains reliably sensitive to penicillin, and penicillin or amoxicillin is the treatment of choice for streptococcal pharyngitis. A single intramuscular (IM) dose of benzathine penicillin G is an option when adherence to a 10-day oral course is a concern, because it provides long-acting blood levels for about three to four weeks (Shulman et al., 2012). Three features of the drug matter for Mr. Beatty: it is cleared mainly by the kidneys, it can cause severe allergic reactions including anaphylaxis, and the long-acting benzathine form must never be given intravenously.

Answers and rationales

1. Information to collect before giving penicillin G

• Allergy history: any previous reaction to penicillins, amoxicillin, cephalosporins or carbapenems, including what happened (rash, hives, swelling, breathing difficulty, anaphylaxis). About 10% of people report a penicillin allergy, although most are not truly allergic; a history of anaphylaxis is a contraindication (Burchum & Rosenthal, 2022). Also ask about allergy to procaine if a procaine-containing product is ordered.
• Renal function: most recent serum creatinine, estimated glomerular filtration rate (eGFR), BUN and potassium, because penicillin G is excreted by the kidneys and can accumulate, increasing the risk of neurotoxicity (including seizures) and electrolyte disturbances.
• Current medications: including probenecid (raises penicillin levels), anticoagulants, potassium-sparing diuretics, ACE inhibitors or potassium supplements, and other nephrotoxic drugs.
• Baseline assessment: vital signs, oxygen saturation, lung sounds, weight, and throat and lymph node findings to compare after the injection.
• Other history: asthma or other allergies (which increase the severity of allergic reactions), cardiac history, bleeding disorders (relevant to IM injection), and any prior reactions to injections.
• Verification: confirm the exact product ordered (benzathine penicillin G versus a procaine combination or aqueous penicillin G), the dose and route, and that the order is adjusted for renal function if needed.

2. Why not an oral medication?

The nurse should explain that oral penicillin or amoxicillin is also an effective treatment for strep throat, but it must be taken several times a day for a full 10 days to eradicate the bacteria and prevent complications such as rheumatic fever. A single long-acting IM injection guarantees a complete course of treatment in one visit and keeps antibiotic levels in the blood for several weeks (Shulman et al., 2012). The provider may have chosen the injection because of concerns about completing a 10-day oral course or absorption. The nurse should support informed decision-making: if Mr. Beatty prefers oral therapy and can reliably complete it, the nurse should communicate his question and preference to the provider rather than simply dismissing it.

3. Equipment needed before administration, and why

• Correct medication and supplies: verified benzathine penicillin G prefilled syringe; an appropriate needle length and gauge for a deep IM injection (for example, 1 to 1.5 inches, 21–22 gauge, depending on body size); alcohol swabs, gloves, gauze and bandage; sharps container.
• Emergency equipment for anaphylaxis: epinephrine 1 mg/mL for IM injection (auto-injector or vial with syringe), diphenhydramine, and access to IV supplies and fluids, corticosteroids and an inhaled bronchodilator.
• Airway and resuscitation equipment: oxygen and delivery devices, suction, a bag-valve-mask, an emergency cart with an automated external defibrillator (AED) or defibrillator, and a way to call emergency responders.
• Monitoring equipment: blood pressure cuff, pulse oximeter and stethoscope.

Why: anaphylaxis can develop within minutes of a penicillin injection and can progress to airway obstruction, shock and cardiac arrest. Because the drug is injected IM and is long-acting, it cannot be removed once given, so the nurse must be ready to treat a reaction immediately. Patients should be observed for at least 30 minutes after a penicillin injection.

4. Potential causes of the cardiac arrest

• Anaphylaxis: a type I (IgE-mediated) hypersensitivity reaction causing massive histamine release, vasodilation, capillary leak, bronchospasm and airway swelling. The resulting hypotension and hypoxia can cause cardiovascular collapse. This is the most likely cause.
• Inadvertent intravascular injection: benzathine penicillin G is a suspension that must be given by deep IM injection only. Accidental injection into a vein or artery has been associated with cardiorespiratory arrest and death, as well as severe tissue damage. This is why the manufacturer’s labeling carries a warning against intravenous administration (Burchum & Rosenthal, 2022).
• Hyperkalemia: some penicillin G preparations, such as aqueous penicillin G potassium, contain potassium. In a patient with chronic renal insufficiency, reduced potassium excretion could lead to hyperkalemia and fatal dysrhythmias.
• Procaine reaction (Hoigné syndrome): if a product containing procaine penicillin was used, procaine toxicity can cause anxiety, hallucinations, seizures and, rarely, cardiovascular collapse.
• Medication error: wrong product, dose or route, especially confusion between benzathine and procaine formulations or between long-acting and aqueous penicillin G.
• Underlying conditions: preexisting cardiac disease or electrolyte imbalances related to kidney disease could increase vulnerability.

5. Discharge teaching related to penicillin G

• Allergy documentation: Mr. Beatty should be told clearly that he had a serious reaction and must avoid penicillins; the allergy should be recorded in his health record and he should wear a medical alert bracelet. He should inform every provider, pharmacist and dentist, and discuss with his provider possible cross-reactivity with cephalosporins and carbapenems.
• Emergency plan: if prescribed, how and when to use an epinephrine auto-injector, and to call 911 for symptoms such as hives, swelling of the face or throat, wheezing, dizziness or chest tightness.
• Delayed reactions: report rash, fever, joint pain or swelling over the next one to two weeks (possible serum sickness-like reaction), and injection site pain, swelling or color changes.
• Infection follow-up: because the antibiotic was given as one dose, he does not need to take pills at home, but he should report persistent sore throat, fever or swelling. If treatment was interrupted by the reaction, the provider will prescribe an alternative antibiotic that is safe for him and appropriate for his kidney function.
• Kidney health: keep follow-up appointments for kidney function and potassium checks, stay hydrated as directed, and ask before taking any new medications, including NSAIDs, which can harm the kidneys.
• Preventing spread: he is generally no longer contagious after 24 hours of antibiotic therapy; he should wash hands, avoid sharing utensils and replace his toothbrush.

Use teach-back to confirm that Mr. Beatty can state his allergy, the warning signs of a reaction and when to seek help.

Frequently asked questions

Related reading: clinical reasoning case studies series and subjective vs. objective nursing data.

References

Burchum, J. R., & Rosenthal, L. D. (2022). Lehne’s pharmacology for nursing care (11th ed.). Elsevier.

Shulman, S. T., Bisno, A. L., Clegg, H. W., Gerber, M. A., Kaplan, E. L., Lee, G., Martin, J. M., & Van Beneden, C. (2012). Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clinical Infectious Diseases, 55(10), e86–e102. https://doi.org/10.1093/cid/cis629