Scope
This guideline covers the assessment and treatment of cellulitis in both adults and children within forward medical environments and in the deployed hospital environment. It includes guidance on distinguishing uncomplicated from complicated cellulitis.
Antibiotic choice should be guided by the Deployed Antimicrobial Guidance CGO.
Since resistance patterns vary widely around the world and with different nationalities, discussion with DMS Microbiology via clinical reach back is advised if initial treatment is failing.
For advanced management of severe soft tissue infections such as necrotising fasciitis, follow the Severe Soft Tissue Infection CGO (link to follow).
Initial Assessment & Management
Clinical Features
Localized erythema, warmth, swelling, and tenderness. Commonly affects lower limbs but may occur anywhere. May be accompanied by systemic symptoms: fever, malaise, rigors.
History
Onset and duration of symptoms.
Recent trauma, bites, injections, surgery, tattoos, piercings or skin conditions.
Previous episodes of cellulitis.
Comorbidities: diabetes, peripheral vascular disease, immunosuppression.
Recent travel or aquatic exposure (may suggest unusual pathogens).
Examination
Mark (and date) the border of erythema. If possible take photo on MedIS or similar.
Check for systemic involvement: fever, hypotension, tachycardia.
Assess for abscess or fluctuance. (Consider PVL infection)
Evaluate for lymphangitis or regional lymphadenopathy.
Check interdigital spaces for fungal infection.
Cellulitis in special areas (face, ear, groin – see 'special presentations' in accordion content below).
If trained and competent, consider ultrasound imaging for abscess / deep infection.
Assess Severity
Mild: No systemic features
Moderate: Systemic features present but no confusion, hypotension, or immunosuppression
Severe: significant systemic features present (e.g. acute confusion, hypotension). Treat as Necrotising Soft Tissue Infections.
Differential Diagnoses to consider:
Dermatological:
Contact Dermatitis – typically very itchy, minimal pain, exposed areas
Erysipelas – Bright red, swollen, finely dimpled (like an orange)
Guttate Psoriasis – small, red, inflamed patches which later appear scaly.
Vascular:
Deep Vein Thrombosis – recent immobility, tender along veins, calf swelling
Thrombophlebitis – hard cord like vessel with distal redness
Travel / Environmental:
Cutaneous Larva Migrans – itchy, linear/serpentigious due to hookworm
Cutaneous Leishmaniasis – Painless papule becoming ulcer, slow progression
Scabies – very itchy, worse at night, 5-10mm burrows, can become generalised
Other:
Septic Joint / Gout – single isolated red, hot joint with limited range of motion
Start Treatment
- Elevate affected limb if possible +/- application of splint immobilisation if possible and appropriate.
- Address any underlying cause (e.g., tinea pedis with foot hygiene, Clotrimazole 1% TDS)
- Commence antimicrobial therapy, refer to DMS Deployed Antimicrobial Guidance CGO:
- Mild: Oral antibiotics suitable.
- Moderate: Bed patient down (if able). Consider once only IV antibiotic regime. Aim for switch to oral agents after 48hrs.
- Severe: treat as a potential necrotizing soft tissue infection. Urgent IV antibiotics, IV fluid resuscitation, urgent surgical/orthopaedic review for consideration of necrotising fasciitis.
If severe cellulitis / necrotising soft tissue infection is suspected, ensure: basic medical management for sepsis is delivered (IAW Immediate Management of the Septic Patient CGO - link to follow): oxygen, IV fluid resuscitation, IV antibiotics.
Necrotising soft tissue infections are time-critical medical emergencies. Prioritise these patients for evacuation to a setting where surgical assessment and management can be delivered as soon as possible.
Abscess Management
Start antimicrobial therapy IAW the Deployed Antimicrobial Guidance CGO
If trained and competent to do so, incise and drain the abscess.
If access to microbiology testing is available, take a swab of pus (skin swabs without pus have low diagnostic yield). Ensure that testing specifically for PVL is included in the request.
Adjunctive Treatments
Analgesia and antipyretics (ibuprofen and / or paracetamol). Ibuprofen has been shown to speed resolution of redness in cellulitis as well as decrease pain.
In patients who must return to duty urgently there is some evidence that a single dose of 60mg of oral Prednisolone speeds resolution and decreases discomfort.
Splinting and immobilising the affected limb (if practical) can contribute to pain-management.
Monitoring
Mild: Review patient in 48-72 hours and expect to see visible improvement. Reassess for any collections.
Moderate: Review patient at 12 and 24 hours to ensure not becoming more systematically unwell. Cellulitis itself may look redder and extend slightly over the first 24 hours compared to the initial marking.
Severe: Switch to oral therapy when clinically improving (fever & rigors gone, redness receding significantly).
The area of redness can be marked on the patient's skin to aid assessment of resolution/progression.
Complications
Abscess formation – may require incision and drainage.
Recurrent cellulitis – consider prophylactic antibiotics for ≥2 episodes/year.
Sepsis – early identification and management crucial. Refer to the Immediate Management of the Septic Patient CGO - link to follow
Lymphoedema – long-term complication of repeated cellulitis.
Thrombophlebitis – especially with lower limb involvement.
Advanced Assessment & Management
Patients attending deployed hospital settings with cellulitis should be managed in accordance with the recommendations in 'Initial Assessment & Management' above.
Patients with only mild illness generally do not require laboratory tests. In patients with signs of systemic illness, perform the following investigations in a deployed hospital setting, if available:
- Serum biochemistry: to include renal profile, LFTs and CRP.
- Blood cultures: perform in all patients requiring deployed hospital treatment, and in patients without systemic symptoms if atypical organisms are suspected (e.g immersion injury) or who are immunocompromised.
- Clinical imaging (depending on availability):
- Xray, ultrasound and MRI may all help confirm a diagnosis of osteomyelitis, local abscess or necrotising soft tissue infection. Only perform if osteomyelitis, necrotising soft tissue infection or abscess is suspected. Imaging must not delay surgical assessment.
For surgical management of soft tissue infections see the specialty-specific CGO [link to follow].
Paediatric Considerations
The principles of managing cellulitis in children are the same as for adult patients.
Specific differentials to consider in the paediatric population include:
- Allergic/contact dermatitis: if itchy and non-tender, cellulitis is unlikely.
- Impetigo: well-defined lesions, often crusting, systemically well.
- Staphylococcal scalded skin syndrome: blistering exfoliative rash triggered by exotoxin release from Staph aureus bacteria. Rare. Predominantly seen in children under 5, with a peak onset of 2.5yrs. Usually spares the mucous membranes (unlike toxic epidermal necrolysis). A paediatric medical emergency requiring IV antibiotics and treatment in a specialist paediatric setting.
- Septic arthritis or osteomyelitis: in young infants with erythema over a joint or bone.
Ensure pain is adequately treated in children – refer to the analgesia CGO (link to follow)
