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1 Title of Guideline (must include the word Guideline (not protocol, policy, procedure etc) Contact Name and Job Title (author) Directorate & Speciality Guideline for the management of skin and soft tissue infection Dr P Venkatesan Consultant in Infectious Diseases DIRC Infectious Diseases Date of submission Date on which guideline must be reviewed Before Explicit definition of patient group to which it applies (e.g. inclusion and exclusion criteria, diagnosis) Adult patients under the care of Infectious Diseases Abstract This guideline describes the management of skin and soft tissue infection, including cellulitis. Key Words Cellulitis, Necrotising Fasciitis Statement of the evidence base of the guideline has the guideline been peer reviewed by colleagues? Evidence base: (1-5) 1a meta analysis of randomised controlled trials 1b at least one randomised controlled trial 2a at least one well-designed controlled study without randomisation 2b at least one other type of well-designed quasiexperimental study 3 well designed non-experimental descriptive studies (ie comparative / correlation and case studies) 4 expert committee reports or opinions and / or clinical experiences of respected authorities 5 recommended best practise based on the clinical experience of the guideline developer Consultation Process Target audience Grade 1b Reviewed within Infectious Diseases and Microbiology Drafts circulated amongst Consultants in above specialties. Infectious Diseases team This guideline has been registered with the trust. However, clinical guidelines are guidelines only. The interpretation and application of clinical guidelines will remain the responsibility of the individual clinician. If in doubt contact a senior colleague or expert. Caution is advised when using guidelines after the review date.

2 Clinical guidelines are guidelines only. The interpretation and application of clinical guidelines will remain the responsibility of the individual clinician. If in doubt contact a senior colleague or expert. Caution is advised when using guidelines after the review date. The most up to date version of this guideline is on the Infectious Diseases Website. GUIDELINE FOR THE DIAGNOSIS AND MANAGEMENT OF SKIN AND SOFT TISSUE INFECTION A. INTRODUCTION There is a range of manifestations of skin and soft tissue infection (SSTI). The most common form is cellulitis an acute, diffuse and suppurative inflammation of dermis and subcutaneous tissue. The diagnosis of cellulitis implies an infectious aetiology. When assessing a patient with cellulitis, a high index of suspicion for deeper necrotising conditions such as necrotising fasciitis must be maintained. Prompt surgical debridement is essential for necrotising soft tissue infections. B. ASSESSMENT AND DIAGNOSIS 1. Clinical Assessment The clinical assessment should consider the patient s susceptibility, exposures and clinical features. Susceptibility Features to be considered include - Obesity, oedema (including lymphoedema), diabetes, neutropaenia, immunosuppression. - Portal of entry such as injury, bites or fungal infection (particularly tinea pedis), ulcers, IVDU injection sites, indwelling devices. Exposures A portal of entry may be exposed to endogenous skin flora or exogenous organisms from bites or the environment. Travel abroad adds an extra dimension. Clinical features There should be an assessment of - local clinical features. - the systemic inflammatory response (pulse / temp / BP) and The former should include an assessment of the duration, onset, progression and extent of infection. The affected area should be marked with a water insoluble marker to allow for later comparison. Any history of prior antibiotics, their dose and effect should be recorded. The precise clinical form of SSTI should be defined. 2. Clinical forms of SSTI The clinical forms of SSTI vary by anatomical location, tissue injury in addition to tissue inflammation and the rapidity of progression. Anatomical location Infection may affect dermal, sub dermal and / or associated tissues.

3 - In cellulitis there is infection involving the dermis and subcutaneous tissue. Cellulitis exhibits the hallmarks of inflammation with tenderness, warmth, erythema and swelling, but without sharp demarcation from surrounding tissue. - Erysipelas is typically an erythematous patch with well demarcated, raised borders due to local oedema and often lymphatic involvement. The responsible organism for erysipelas is usually Group A Streptococcus. For practical purposes both erysipelas and cellulitis are treated similarly. - Impetigo is classically due to Staphlyococcus aureus, and is predominantly an infection of the dermis, with exudate and crusting on the skin surface. - A boil or furuncle may start in a dermal structure, extends into the subcutaneous tissue but may point out through the dermis. - A carbuncle is a collection of boils which cross connect in subcutaneous tissue. - Associated tissues which may be secondarily or primarily infected are lymphatics (lymphangitis), tendon sheaths (tenosynovitis), muscle (myositis), connective tissue plains (e.g. fasciitis), bursae (bursitis), joints and bone. Tissue injury There are three key forms of tissue injury - blistering (due to skin damaging toxins or local ischaemia) - abscess formation and - tissue necrosis. Tissue necrosis arises from bacterial necrotic toxins (e.g. Bacillus anthracis) or local ischaemia from local intravascular coagulation (e.g. ecthyma) or vascular compression from tense oedema and inflammation. The latter occurs in necrotising fasciitis in which tension in deep tissues comprises blood flow to the overlying skin. What is apparent on the surface may not be in proportion to the extent of deep tissue inflammation and injury. Necrotising soft tissue infection is possible in the presence of the following features (percentages specifically apply to necrotising fasciitis, which has a mortality of 20 40%): - Tense oedema (23% 80%) particularly if present beyond the margin of erythema - Purplish skin discolouration due to infarction (10% 70%) - Cutaneous haemorrhage due to the breakdown of vessel walls - Bullae (12 45%) - Sloughing of the skin - Pain disproportionate to physical findings - Sensory or motor deficit due to neural injury (13%) - Gas in the tissue with crepitus when infection is due to gas forming organisms (7 25%) - Rapid progression despite the presence of antibiotics

4 It is important to identify potential polymicrobial necrotising infection, as this would affect antibiotic therapy. Necrotising infection in the following settings is suggestive of polymicrobial infection: - Abdominal surgery or trauma - Necrotising infection associated with a pressure ulcer or an abscess - Injection site of IVDU - In association with a Bartholin abscess or vulvovaginal infection Rapidly progressive forms of SSTI Evolution of extensive inflammation within 24 hours is regarded as rapidly progressive and is more often seen with the following pathogens - Group A Streptococcus (rapidity related to toxin production and erythema) - Staphylococcus aureus - Clostridium spp amongst IVDUs - Pasteurella spp related to bites - Aeromonas hydrophila - Vibrio spp in fish handlers 3. Pathogens Susceptibilities, exposures and clinical features may suggest particular pathogens e.g. - Diabetic foot ulcer (mixed Gram negative organisms, S aureus, Group B Streptococcus and anaerobes) - Neutropaenic patients (Gram negative organisms, Pseudomonas) - Dog or cat bites (Pasteurella) - Human bites (organisms of the oral flora) - Exposure to fresh or sea water (Aeromonas, Vibrio vulnificus) - Travel history (wide differential: eg Rickettsial infection, Leishmania) - IVDU (Staphylococcus aureus, Clostridia) - Recurrent boils / abscesses (PVL Staphylococcus aureus) - Unusual clinical features such as black eschar or nodules (e.g. Bacillus anthracis, particularly in conjunction with travel history). 4. Differential diagnosis The following features should prompt the consideration of alternative diagnoses: - Bilateral involvement - Lack of change in inflammatory markers - Joint involvement (note septic arthritis is a differential) Differential diagnoses include - bilateral oedema with a change in skin colour due to sluggish blood flow - varicose eczema related to venous insufficiency, epithelial breakdown, plasma exudate and skin irritation (characteristically with this there may be itch, history of venous insufficiency, vesicles and crusting, with no fever or leucocytosis, although swabs may be positive for colonising organisms) - DVT

5 - Less common differential diagnoses include arthritis (where joints are involved), erythema nodosum, pyoderma gangrenosum, and Sweet s syndrome. In a US series of 145 patients hospitalised for cellulitis other diagnoses were made in 28%, usually varicose eczema / stasis dermatitis. 5. Investigations Laboratory investigations should include the following - FBC, U&E, CRP, Glucose. - MRSA screen. - Blood cultures are positive in <5% of patients with non complicated cellulitis, and should be reserved for patients with systemic toxicity or unusual features. - A superficial swab cannot distinguish between colonisation and infection. - Imaging is not usually indicated for non complicated cellulitis, although there may be a place for ultrasound or MRI if there is concern about abscess formation and deep tissue involvement. Cellulitis with unusual features More aggressive microbiological investigation should be considered in cellulitis with unusual features. Methods to obtain samples include tissue aspirate and tissue biopsy. - The microbiological yield of a tissue aspirate is between <5 40%. This involves injecting and aspirating 0.5 1ml of sterile saline (mixed with air) from the intradermal layer, using a syringe attached with a needle. - The microbiological yield of a skin biopsy is 20 30%. Biopsy samples should be divided and sent to histopathology (in a formalin pot) and microbiology (in a sterile universal, without formalin, but containing some sterile saline). - Any subcutaneous collection should be aspirated to dryness and the pus sent to microbiology. Cellulitis associated with recurrent boils or abscesses should raise the suspicion of PVL Staphylococcus aureus infection. A nose, groin and perineal swab should be taken for PVL Staphylococcus aureus. The swabs could be taken in a manner similar to that for MRSA colonisation screening, but the request form should be clearly labelled recurrent boils, surveillance screen for PVL Staphylococcus aureus. The microbiology laboratory should be notified prior to sample collection if unusual pathogens such as Rickettsia, cutaneous anthrax or Leishmania are suspected, so that the samples are inoculated in the appropriate culture media and biosafety measures undertaken. Investigations when necrotising soft tissue infection is suspected Where necrotising infection is suspected, management should be initiated without delay. Additional investigations should include

6 - CK and - Clotting and Group & Save, in preparation for emergency surgical debridement. - Gas may be demonstrated in up to a third of patients with plain a X Ray. - CT and MRI could also demonstrate the involvement of deeper tissue. However pursuing imaging may cause unacceptable delay to debridement, thus necrotising soft tissue infection remains a clinical diagnosis in practise. C. MEDICAL MANAGEMENT 1. Referrals - The diabetes and endocrinology team should be informed of all patients admitted with cellulitis associated with diabetic foot ulcers. - A referral to the infectious diseases team should be considered for patients admitted with cellulitis associated with unusual clinical features detailed above (except for patients with diabetic foot ulcers). - A referral to the plastic surgeons should be considered for patients affected by animal or human bites, particularly in clench fist injuries. - An urgent referral to a senior plastic surgeon is mandatory for all patients suspected of having a necrotising soft tissue infection. 2. Antibiotic therapy Cellulitis and simple SSTI Antibiotic guidance for cellulitis can be found on the Antibiotic website ( nsofttissuemain.aspx ). The antibiotic choices include - Flucloxacillin (ranging from 2 g qds iv to 500 mg qds orally) - Clarithromycin (500 mg bd orally, if allergic to penicillin and mild cellulitis) - Clindamycin mg oral or iv - Vancomycin The most common organisms causing cellulitis are Streptococcus pyogenes and Staphylococcus aureus. There is considerable variation in the rates of MRSA worldwide, thus published empirical antibiotic regimes in the literature are not necessarily appropriate for local practise. The traditional practise of administering benzylpenicillin and flucloxacillin concurrently is not supported by trial evidence, as the spectrum of the latter covers the spectrum of the former, but not vice versa (II B). Antibiotics should be administered for 7 10 days. Parenteral antibiotic treatment beyond four days is often unnecessary. The duration of therapy was 7 14 days in most drug trials, but a study found five days of treatment was as effective as ten days of treatment.

7 Lack of improvement Consider the following if the patient does not improve after two days of effective treatment: - resistant organism such as MRSA, - factors leading to slow response such as general frailty or lymphoedema, - alternative diagnosis, - progression to necrotising infection. In the absence of other complications, consider the addition of clindamycin ( mg po qds) if the patient does not improve on flucloxacillin monotherapy (III C). Clindamycin is well absorbed so the oral route is usually adequate, except when the patient is vomiting. The use of clindamycin is associated with the development of Clostridium difficile diarrhoea and the patient should be told to report diarrhoeal symptoms promptly. Bites Antibiotic guidance for simple animal or human bites are to be found on the intranet. The spectrum of pathogens differs. Antibiotics for animal bite wounds should cover Pasteurella for which first generation cephalosporins, macrolides and clindamycin have little activity and should be avoided as monotherapy (III D). Coamoxiclav is the usual first line choice. Other antibiotic options include metronidazole + doxycycline, metronidazole + fluoquinolone, metronidazole + cefuroxime or cotrimoxazole. Infection from deeper bite wounds penetrating the synovium or injuring bone requires 3 4 weeks of therapy for tenosynovitis / arthritis or 4 6 weeks of therapy for osteomyelitis. There are special considerations for bites from monkeys which carries a risk of transmission of B virus (also known as herpes virus saimiri). B virus infection in human has a high fatality. Prophylaxis with valaciclovir (1gram tds 14 days) should be given with high risk exposures. Patients with bite wounds from animals in rabies endemic countries should be considered for rabies prophylaxis (link). Necrotising infection Discuss the antibiotic treatment of all patients with necrotising soft tissue infection with the Consultant Microbiologist or Consultant in Infectious Diseases urgently. The antibiotic regime depends on whether the infection is likely to be polymicrobial or monmicrobial. Suggested regimes for polymicrobial necrotising infection (III A) include - Tazocin (4.5gram tds) AND clindamycin (600mg qds) AND ciprofloxacin (500mg bd) - Meropenem (1 gram tds) OR ertapenem (1 gram od)

8 - Cefotaxime (2gram qds) AND metronidazole (500mg qds) AND clindamycin (600mg qds) Suggested regimes for infection with a single organism (II A) include - Benzylpenicillin AND clindamycin 3. Adjunctive therapy Interdigital fungal infection should be treated with topical terbinafine bd for one week (III B). D. NURSING ISSUES Patients with cellulitis should have observations as per Trust guidance. Patients with suspected necrotising infection can deteriorate precipitously and should be observed closely; 2 4 hourly observation should be maintained. Patients with recurrent skin abscesses might be colonised with PVL St. aureus. When PVL St. aureus carriage is confirmed, the patient should be isolated and given decolonisation treatment. The preferred decolonisation treatment is five days of aquasept/chlohexidine body wash/ shampoo and nasal bactroban (identical to MRSA eradication therapy). E. DISCHARGE AND FOLLOW UP Afebrile patients who are otherwise healthy do not require admission. Early discharge with daily attendance to Nightingale ward for further parenteral antibiotics should be considered for patients with no unstable co morbidities who responded to initial treatment. However, patients with bite wounds, infection in periorbital area, joints, scrotum or neck are not suitable candidates for early discharge. Patients with simple cellulitis do not require routine follow up. There is no good quality evidence supporting the use of antibiotic prophylaxis. However, both the CREST guideline development group and British Lymphology Society recommend antibiotics prophylaxis for patients with recurrent cellulitis. Patients with more than two episodes of cellulitis at the same site and recognised predisposing factors (e.g. local lymphoedema) may be considered for long term prophylactic antibiotic therapy. Suitable regimes include penicillin V 250mg bd or erythromycin 250mg bd. Patients with complicated cellulitis should be followed up at the discretion of the attending physician. F. REFERENCES AND EXTERNAL GUIDELINES External guidelines Fulton R. et al

9 Guidelines on the Management of Cellulitis in Adults. (Guidelines from Clinical Resource Efficiency Support Team, Northern Ireland) Stevens DL. et al. Practice Guidelines for the diagnosis and management of skin and soft tissue infections. (These are guidelines from the IDSA) Clinical Infectious Diseases 2005;41: (link) References Dryden MS. Complicated skin and soft tissue infection. Journal of Antimicrobial Chemotherapy 2010;65:suppl3:iii Cohen JI et al. Recommendations for Prevention of and Therapy for Exposure to B virus (Cercopithecine herpesvirus 1). Clinical Infectious Diseases ;35: David CV et al. Diagnostic accuracy in patients admitted to hospitals with cellulitis. Dermatology Online Journal 2011;17:1. Eron LJ et al. Managing skin and soft tissue infections: expert panel recommendations on key decision points. Journal of Antimicrobial Chemotherapy. 2003;52(S1):i3 i17 Hepburn MJ et al. Comparison of short course (5 days) and standard (10 days) treatment for uncomplicated cellulitis. Arch Intern Med 2004;164: Shimizu T and Tokuda Y. Necrotizing fasciitis. Internal Medicine 2010;49: Sultan HY et al. Necrotising fasciitis. British Medical Journal 2012:345:43 5 Swartz MN. Cellulitis. New England Journal of Medicine 2004;350: (link) Vinh DC, Embil JM. Rapidly progressive soft tissue infections.

10 Lancet Infectious Diseases 2005;5:

11 AUDIT FORM Date : Please print off the guideline together with this audit form. Place the audit form on the front of the notes and complete the form at discharge or when dictating the discharge summary. On completion please return this audit form to Dr Venkatesan. Hospital number : Diagnosis : Cellulitis / Other SSTI (please state) : History and examination adequate Yes No (please detail) Investigations as per guideline Yes No (please detail) Management as per guideline Yes No (please detail) Discharge and follow up as per guideline Yes No (please detail) Outcomes Full recovery Complications (please state) Death (please give details) Near misses / Serious incidents Yes (please detail) No Could we have done better? Yes (please detail) No