Pharmacology

Skin and Soft Tissue Infections-Impetigo

Case Study

Patient Profile

Name: Sammy

Age: 2 years old

Gender: female

Current Medications

None

History of Present Illness

Sammy is a two-year-old girl with benign medical history who attends day care and presents today with concern for a rash on her face. The rash is under her nose and on her upper lip. The mother reports that there are children at the day care who she saw with a similar rash when she picked her daughter up yesterday. The rash appeared rapidly; there are tiny blisters on a pink–toned rash. Where blisters have broken, there is a honey-colored crusty appearance. Figure 1 shows a picture of a similar rash.

Young girl with red, itchy initially fluid filled vesicles around nose and mouth that burst and drain fluid that dries with a yellow crust.
Figure 1. Impetigo rash

Sammy has been playing, eating, drinking, and urinating as usual. There has been no diarrhea or constipation. Sammy has received all recommended immunizations.

Relevant Assessment

Vital signs: Afebrile. Heart rate and respiratory rate within normal range.

HEENT: Normocephalic, atraumatic. Eyes: EOMI. PERRLA. No injection or drainage. Ears: Canals clear. TMs intact, bony landmarks visible, cone of light visible bilaterally. No effusions, injection, erythema, bulging or retractions bilaterally. Nose: Patent bilaterally. Mucosa: No erythematic, pale, or evidence of epistaxis. Throat: Tonsils 2+ bilaterally, no erythema or exudate. Posterior oropharynx: No erythema or exudate.

Integumentary: Vesicular rash on erythematous base on upper lip under nose. Some vesicles are intact, others are ruptured and moist. Other lesions are ruptured but with honey-colored crusted drainage.

No other expanded review of system (subjective data) or examination (objective data) has an impact on the diagnosis reviewed in this case.

Differentials

Non-bullous, bullous impetigo, chicken pox, herpes labialis, atopic dermatitis (eczema), Steven Johnson’s syndrome, tinea infection, thermal burn, chemical burn

Diagnosis

Impetigo

Diagnostic Testing

None at this time

Referrals

None at this time

Patient/Provider Collaborative Goals

The rash will be substantially improved or clear by time of planned follow-up.

Therapeutic Interventions

  1. Describe a first-line pharmacologic treatment: Include drug name, dose and formulation, frequency, and length of treatment at this dose.
    Answer:

    One option is mupirocin cream 2% topically to rash around nose and upper lip every 8 hours for 10 days.

    • Drug Mechanism of Action:
      Answer:

      Mupirocin (Bactroban) inhibits protein synthesis by binding to bacterial isoleucyl transfer-RNA synthetase.

    • Contraindications if applicable:
      Answer:

      Hypersensitivity to mupirocin (Bactroban) or any of the formulation’s components.

  1. Therapeutic advisement and monitoring: (include any specific instructions that apply, such as when to take the medication, if there are foods to avoid, storage issues, etc; include what laboratory/other (i.e., EKG) test monitoring to expect and how often and monitoring for adverse effects both common and serious)
    Answer:

    Patients should also be advised to call with any questions or concerns.

    • Therapeutic Monitoring: There is no recommendation for specific monitoring of mupirocin (Bactroban) therapy.
    • Monitor Side/Adverse Effects: There are no documented side/adverse effects that have an occurrence rate of 10% of the time or greater.
  1. Planned follow-up should consider adverse effect monitoring, dose adjustment considerations, and decisions about continuing versus discontinuing. In this case, planned follow-up would be:
    Answer:

    NP or designated office staff should initiate a follow-up by phone call 48-72 hours after starting treatment. If the rash shows no improvement in 48-72 hours, the patient should return to the office for culture for MRSA and switch to antibiotics that are appropriate for MRSA infection. Otherwise, the follow-up office visit should be in five days to re-evaluate the rash.

Review Questions

Click the arrow to expand the section and view the correct answers.

  1. What is the first-line medication treatment for limited non-bullous impetigo?
    1. Ozenoxacin
    2. Bacitracin
    3. Neomycin
    4. Mupirocin
Answer:

D. Mupirocin

Feedback: Limited non-bullous impetigo can be treated with topical mupirocin. More extensive impetigo may require treatment with oral antibiotics.

  1. Which of the following is not an acceptable treatment for impetigo?
    1. Azithromycin
    2. Mupirocin
    3. Cephalexin
    4. Clindamycin
Answer:

A. Azithromycin

Feedback: Azithromycin is an antibiotic medication and is not Food and Drug Administration-approved to treat impetigo. Approved treatments include mupirocin (Bactroban), cephalexin (Keflex), dicloxacillin, clindamycin (Cleocin), and amoxicillin/clavulanate (Augmentin).

  1. Impetigo is very contagious; therefore, in addition to the treatment with medication, education should include daily showering or bathing with antibacterial soap, avoiding sharing towels, and diligent handwashing. (True or False)
    1. True
    2. False
Answer:

A. True

Feedback: Impetigo is very contagious; therefore, in addition to the treatment with medication, measures to reduce the spread of the infection should include education about daily showering or bathing with antibacterial soap, avoiding sharing towels, and diligent handwashing.

  1. Which of the following medications are used to treat atopic dermatitis (eczema) (Select all that apply)?
    1. Calcitriol (Vitamin D)
    2. Dupilumab (Dupixent)
    3. Crisaborole (Eucrisa)
    4. Pimecrolimus (Elidel)
    5. Methotrexate
Answer:

B. Dupilumab (Dupixent); C. Crisaborole (Eucrisa); D. Pimecrolimus (Elidel)

Feedback: Options to treat atopic dermatitis (eczema) include PDE-4 inhibitors, topical immunosuppressants, and immunomodulators. An example of a PDE-4 inhibitor is crisaborole (Eucrisa). Topical immunosuppressants include pimecrolimus (Elidel) and tacrolimus (Protopic). An example of an immunomodulator is dupilumab (Dupixent).

  1. You have a patient being treated with an immunomodulator for atopic dermatitis (eczema) presenting for a sick visit with complaints of fever, nausea, vomiting, diarrhea, and rash. The patient is tachycardic, hypotensive, tachypneic, and not thinking clearly. Which of the following may be the explanation for this presentation?
    1. Anaphylaxis
    2. Gastrointestinal toxicity
    3. Hepatoxicity
    4. Cytokine release syndrome
Answer:

D. Cytokine release syndrome

Feedback: Immunomodulators may stimulate the release of proinflammatory cytokines from leukocytes. Symptoms may include fever, nausea, vomiting, diarrhea, and rash. More severe symptoms are delirium, seizures, tachycardia, tachypnea, and hypotension. Treatment is supportive, which may include hospitalization for initial stabilization.

  1. Ryan is a 15-year-old male wrestler. He presents with an erythematic annular well demarcated rash on his arms and neck. The rash developed about five days after a long weekend of a wrestling tournament. It is itchy without any drainage. Your diagnosis is tinea corporis. Which of the following could treat this skin condition?
    1. Fluconazole (Diflucan)
    2. Oteseconazole (Vivjoa)
    3. Miconazole (Lotrimin)
    4. Voriconazole (Vfend)
Answer:

C. Miconazole (Lotrimin)

Feedback: Treatment for tinea corporis (ring worm) includes antifungal drugs. Medications approved by the Food and Drug Administration to treat tinea corporis include azole antifungals (such as miconazole, clotrimazole, and ketoconazole) and allylamines (such as terbinafine).

  1. You are seeing a 25-year-old female for concern of development of a rash after being started on a medication for simple cystitis (urinary tract infection). You note there are erythematic lesions with vesicular lesions on the lips and the palmar surface of both hands. Which medication used to treat simple cystitis, and pelvic discomfort associated with it, is most likely to have caused what you believe to be Steven Johnson Syndrome?
    1. Trimethoprim/sulfamethoxazole (Bactrim)
    2. Phenazopyridine (Pyridium)
    3. Acetaminophen (Tylenol)
    4. Ibuprofen (Advil)
Answer:

A. Trimethoprim/sulfamethoxazole (Bactrim)

Feedback: Antibiotics known to cause Steven Johnson Syndrome include sulfonamides, penicillins, cephalosporins, fluoroquinolones, and macrolides; the most common are sulfonamides.

  1. A 74-year-old female presents for a sick visit with complaint of pain, redness, and swelling of the right lower leg after having accidentally hit her lower leg on the corner of a picnic table bench three days prior. She denies fever, chills, swollen lymph nodes, nausea, vomiting, or drainage from the wound. You diagnose her with cellulitis, however due to the localized nature and lack of systemic symptoms and signs you feel she can be treated outpatient with by-mouth antibiotics. She has no known medication allergies and no history of intravenous drug use or methicillin resistant staphylococcus aureus (MRSA) infection or colonization. Which of the following options is appropriate?
    1. Amoxicillin
    2. Mupirocin (Bactroban)
    3. Cephalexin (Keflex)
    4. Trimethoprim/sulfamethoxazole (Bactrim)
Answer:

C. Cephalexin (Keflex)

Feedback: Localized cellulitis, without abscess or drainage, suggesting methicillin resistant staphylococcus aureus (MRSA), can be treated outpatient with oral antibiotics. While cephalexin (Keflex) and trimethoprim/sulfamethoxazole (Bactrim) are both Food and Drug Administration-approved for skin and soft tissue infections, trimethoprim/sulfamethoxazole (Bactrim) is only appropriate if MRSA is suspected, and in this case it is not. Cephalexin (Keflex) or dicloxacillin are medication options for this scenario. If the patient has severe beta lactam allergy, then trimethoprim/sulfamethoxazole (Bactrim) would be an appropriate option.

References

Condina Leik, M. T. (2025). Integumentary system review. In FNP Certification Intensive Review (pp. 123–160). Springer Publishing.

Rosenthal, L. D., & Burchum, J. R. (2026). Drugs for disorders of the skin. In Lehne’s pharmacotherapeutics for advanced practice nurses and physician assistants (3rd ed., pp. 830–854). Elsevier.

Rosenthal, L. D., & Burchum, J. R. (2026). Introduction to immunomodulators. In Lehne’s pharmacotherapeutics for advanced practice nurses and physician assistants (3rd ed., pp. 779–781). Elsevier.

Up To Date®. (2025). Mupirocin: Drug information. Lexidrug™. Retrieved June 9, 2025 from https://www.uptodate.com/contents/mupirocin-drug-information

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Be Prepared for Your Nurse Practitioner Clinical Readiness Exam Copyright © 2026 by Elizabeth Heavey, Renee Biedlingmaier, Colleen Burgoyne and Carnel C. Jackson is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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