Moderate -> Fever ( 39 C ) , Abnormal WBC ( 14.2 X 10^9 )

Systemic signs of infection -> Fever, chills, shortness of breath

• Reduction in redness, swelling, warmth, and tenderness

• Decrease in pain score

• Reduction in lesion size

• Normalization of vital signs (fever, HR)

• Decrease in inflammatory markers (WBC, CRP)

  2. Safety

     • Monitor allergic reactions

1. Biotechfront: Type 1 Hypersensitivity - Pathogenesis and Clinical Menifestations

2. Type I Hypersensitivity Reaction - StatPearls - NCBI Bookshelf

3. B Cell Activation and Plasma Cell Differentiation | Immunopaedia

4. B Cells, Memory B Cells and Plasma Cells: B Cell Activation, Development and the B Cell Receptor | Technology Networks

5. Memory Cells vs. Plasma Cells - What's the Difference? | This vs. That

Type of hypersensitivity

1. Penicillin allergy: A practical guide for clinicians

2. Drug allergy - PMC

3. Mechanisms of Drug-Induced Allergy - PMC

4. Penicillin Allergy: Mechanisms, Diagnosis, and Management - ScienceDirect

In fact, it was estimated that about 10% of infections-related hospital admission in the US, and up to 14 million outpatients’ visits annually were due to cellulitis.

add on : people who are more at risk need to treat athlete's foot promptly

A weakened immune system cannot fight bacteria effectively. Diabetes also causes nerve damage, poor wound healing, and high blood sugar, which feeds bacterial growth.

 https://pmc.ncbi.nlm.nih.gov/articles/PMC6303460/

Ref : ·       https://www.ncbi.nlm.nih.gov/books/NBK549770/

Ref : https://www.ncbi.nlm.nih.gov/books/NBK579762/

Ref : https://www.ncbi.nlm.nih.gov/books/NBK459320/

1. Discoloration on his left calf (colored red)

2. Swelling / Edema

3. Warmth feeling on the skin

-> Type 1 hypersensitivity

-> discontinue the cloxacillin immediately

2) According to NAG guidelines

-> pic attached , kindly refer

-> NAG suggested cephalexin

-> in this case, we don't choose this as alternative treatment , it is NOT SAFE for pt

-> why? I will explain shortly

3) what are the safe alternatives?

-> I refer to NAG, medscape and ncbi (pubmed)

-> choose antibiotic with no beta lactic structure for severe penicillin allergy

-> the choices of antibiotic :

• Clarithromycin 500mg BD PO

• Climdamycin 600mg - 1.2 g IV qds

• Doxycycline 100mg BD PO

• IV vancomycin

NAG recommend : Clindamycin 600mg IV q6h

1. Breach of Skin Barrier

• Entry point: trauma, ulcers, bites, fissures, or surgical wounds.

• Allows normal flora (esp. Group A Streptococcus) and other pathogens to penetrate the epidermis.

2. Innate Immune Response

• Keratinocytes detect bacteria → release cytokines (IL-1, IL-6, TNF-α) and chemokines.

• Recruitment of neutrophils, macrophages, dendritic cells to infection site.

• Neutrophils release proteolytic enzymes and reactive oxygen species → tissue inflammation and damage.

3. Vascular Changes

• Local vasodilation → increased blood flow → erythema and warmth.

• Increased vascular permeability → plasma proteins leak into interstitial space → edema.

• Sensitization of nociceptors by cytokines/prostaglandins → pain and tenderness.

4. Epidermal & Dermal Response

• Keratinocyte proliferation and production of antimicrobial peptides (defensins, cathelicidins).

• Formation of inflammatory exudate in dermis and subcutaneous tissue.

5. Bacterial Virulence Factors (Group A Streptococcus)

• M protein: inhibits phagocytosis.

• Hyaluronidase & streptokinase: break down connective tissue, aiding spread.

• Streptolysins: lyse host cells.

• Pyrogenic exotoxins (A, B, C, F) & superantigens: trigger massive cytokine release → systemic toxicity, invasive disease.

6. Clinical Manifestations from Pathophysiology

• Erythema & warmth → due to vasodilation and increased perfusion.

• Edema → from vascular leakage and inflammatory cell infiltration.

• Tenderness/pain → activation of local pain receptors by inflammatory mediators.

• Systemic features (fever, chills, malaise) → cytokine-induced acute phase response.

·    Respiratory distress (difficulty breathing, RR 35 bpm)

·    Angioedema (swollen throat)

·    Flushing (cutaneous manifestation of allergic reaction)

·    Hypotension (BP 90/65 mmHg)

·    Fever (Temp 38.5°C, though this may also relate to infection)

Based on the vital signs above, the first step taken is for the provider to stop/withdraw the use of Cloxacillin.

Then, we can proceed with the appropriate drug treatment for HU's allergy, which is:

·    Intramuscular [I.M.] Epinephrine (Adrenaline)

o Dose: 0.3–0.5 mg IM (0.01 mg/kg in children), repeated every 5–15 minutes as needed

o Site of administration: Mid-anterolateral thigh

o Mechanism of action: Reverses bronchospasm, vasodilation, and reduces mucosal Edema

Adjunctive therapies (Antihistamines & H2 Blockers) can be included:

·    I.V. Diphenhydramine 25 mg to 50 mg. For symptomatic relief such as rashes & itching.

·    I.V. Ranitidine 50 mg. Blocks effects of histamine on H2 receptors, which can help with symptoms like hypotension, and vasodilation, seen in severe allergic reactions.

Source:

https://www.ncbi.nlm.nih.gov/books/NBK459320/ - Penicillin allergy

-Elevated C-reactive protein

-Also an inflammatory marker

-on going inflammation

-Glucose and HbA1c level elevated (age 63 yrs normal 7.1-8%)à slightly higher might be due to stress induce where hormone are release such as cortisol and epinephrine to fight illness

-High temperature (36.5-37.5)

-Medical professional will check medical condition such as:

-No fever for 24-48 hrs

-Improvement in clinical status in hemodynamic status, no respiratory distress, general well being

-Symptoms like swollen throat and flushing face subside

-Tolerate the oral antibiotics and compliance with the oral medication

-Able to manage home care such as cleaning wound and elevatethe affected limb

-No worsening of symptoms

https://www.cdc.gov/dengue/training/cme/ccm/page53639.html

• BP: 90/65 mmHg → hypotension

• RR: 35 bpm → tachypnea/dyspnea

• PR: 102 bpm → tachycardia

• Temp: 38.5°C → fever

1. Blood Pressure: 90/65 mmHg (Low)

   • Normal: 120/80 mmHg

   • Significance: Hypotension indicates systemic vasodilation and fluid shift from blood vessels into tissues due to histamine release in anaphylaxis.

2. Respiratory Rate: 35 breaths/min (High)

   • Normal: 12–20 breaths/min

   • Significance: Fast breathing shows respiratory distress. This is likely due to throat swelling (laryngeal edema) and possible bronchospasm, making it harder to breathe.

3. Pulse Rate: 102 bpm (High)

   • Normal: 60–100 bpm

   • Significance: Mild tachycardia due to the body compensating for low blood pressure. The heart pumps faster to maintain cardiac output.

4. Temperature: 38.5°C (Elevated)

   • Normal: 36.5–37.5°C

   • Significance: Likely related to the underlying wound infection (not directly from the allergic reaction).

Types of Cellulitis suitability for usage of Cloxacillin:

- Mild cellulitis (no systemic signs):

• Cloxacillin 500 mg PO every 6 h, OR cephalexin 1,000 mg PO every 12 h, OR amoxicillin 500 mg PO every 8 h

  - Moderate cellulitis (presence of SIRS but no hypotension):

  • Cloxacillin 1–2 g IV every 6 h

• The foremost objective is to eliminate the causative pathogens, typically Staphylococcus aureus and Streptococcus pyogenes.

• Empirical antibiotic therapy is recommended based on severity (e.g., oral or IV cloxacillin), with adjustments (de-escalation) once culture results are available.

2. Prevent Progression to Severe Disease

• Prompt administration of the appropriate route—oral antibiotics for mild cases, intravenous therapy for moderate disease, and broad-spectrum coverage for severe presentations—is emphasized to avoid complications such as necrotizing fasciitis or systemic involvement.

3. Resolve Clinical Signs and Symptoms

• Treatment aims to resolve erythema, edema, pain, and systemic signs (e.g., fever, tachycardia)—typically within 5–10 days, extending until at least 3 days after acute inflammation subsides.

4. Enable Safe Switch from IV to Oral Therapy

• For hospitalized moderate cases, once clinical improvement is noted, the guideline supports an IV-to-oral (IV-to-PO) switch to promote earlier discharge and reduce healthcare burden.

5. Support Antimicrobial Stewardship

• The guideline underscores the use of narrow-spectrum, Access-group antibiotics whenever possible (e.g., cloxacillin) to minimize antimicrobial resistance.

• De-escalation based on microbiology results is strongly encouraged.

6. Guide Empirical Therapy and Promote Clinical Judgment

• Recommendations provide empirical choices based on severity but explicitly position them as guidance—able to be refined based on individual patient response and laboratory findings

Source: National Antimicrobial Guideline (NAG), Ministry of Health Malaysia - NAG : WHO IS IT MEANT FOR?

Provide medication counseling to patients and caregivers on the correct use of antibiotics (e.g., cloxacillin) and analgesics (e.g., celecoxib), including dosage, frequency, and duration.

Explain the importance of adherence to prevent relapse, resistance, or incomplete treatment.

Educate on side effects (e.g., rash, diarrhea, GI upset, renal effects with NSAIDs) and what actions to take if they occur.

Guide on lifestyle/adjunct measures, such as skin hygiene, limb elevation, and monitoring for signs of worsening infection.

Reinforce antimicrobial stewardship, encouraging patients to complete the prescribed course and not to self-medicate with leftover antibiotics.

2. Raise Awareness on Medicine Allergy

• Identify and document drug allergy history during dispensing, screening for previous penicillin or NSAID reactions.

• Educate patients about common allergy signs (rash, swelling, breathing difficulty, anaphylaxis) and when to seek urgent care.

• Alert healthcare teams about patients’ allergy risks to avoid inadvertent re-prescription of the offending drug.

• Conduct patient education sessions or awareness campaigns in wards, clinics, or community settings to increase understanding of medicine allergies.

• Promote reporting of adverse drug reactions through the Malaysian Adverse Drug Reactions Advisory Committee (MADRAC).

3. Providing Allergy Card

• Issue allergy cards or bracelets to patients with confirmed drug allergies (e.g., penicillin allergy → cloxacillin contraindication).

• Ensure details are recorded on the card: name of drug, type of reaction, date of event, and issuing facility/pharmacist.

• Counsel patients to carry the card at all times and present it to any healthcare professional before receiving treatment.

• Update electronic medical records so that allergy alerts are visible during prescribing and dispensing.

• Promote safety and continuity of care, especially when patients visit different clinics, hospitals, or pharmacies.

4. Cross-Checking and Verification

• Verify allergy status before dispensing — especially high-risk antibiotics like cloxacillin or cephalosporins.

• Act as a final safety checkpoint between prescribers and patients.

• Communicate with prescribers if prescribed medication conflicts with recorded allergy profile.

5. Policy and System Development

• Advocate for mandatory allergy status checks in electronic prescribing systems before order submission.

• Collaborate in developing standard operating procedures (SOPs) for allergy documentation and verification.

• Support integration of national electronic health records that link allergy history across different facilities.

6. Systematic Medication History Taking

• Perform comprehensive medication reconciliation during hospital admission, transfer, and discharge to ensure accurate allergy status is carried forward.

• Ask specific, open-ended questions about prior drug reactions (e.g., “Have you ever had swelling, rash, or difficulty breathing after taking antibiotics?”).

• Differentiate between true drug allergy vs. intolerance/side effects (e.g., nausea from NSAIDs is not an allergy).

7. Staff and Interprofessional Training

• Educate doctors, nurses, and pharmacy staff on the importance of allergy history documentation.

• Provide updates on drug cross-reactivity (e.g., penicillin vs. cephalosporin allergy).

• Conduct in-service training and hospital-wide awareness campaigns on allergy prevention.