Cellulitis

Question 1

What are the causative pathogens of cellulitis?

Answer 1

G+ organisms (79% of cases)

• Staph. Aureus
• Group A Strep
• Group B Strep
• Viridans Strep
• Enterococcus faecalis

G- organisms

• Enterobacteriaceae (e.g. Klebsiella)
• Haemophilus influenzae
• Pasteurella multocida
• Pseudomonas aeruginosa
• Acinetobacter species

Question 2

What is cellulitis?

Answer 2

bacterial entry via skin breaches causing local infection in the dermis and subcutaneous fat manifesting as erythema, oedema, warmth

Question 3

What are sources of infection of cellulitis?

Answer 3

• trauma (surgery, insect bites, injection drug use)
• inflammation (eczema)
• infection (impetigo, tinea pedis, varicella)
• lymphodema/ chronic leg oedema
• previous cellulitis
• BM >30

example of surgeries: liposuction, radical mastectomy, breast conservation therapy, coronary artery bypass

Question 4

how does cellulitis present?

Answer 4

area is tender, warm, erythematous and swollen, lacking sharp demarcation from uninvolved skin

Question 5

what are the pathogens that cause crepitant cellulitis?

Answer 5

clostridia or non-spore forming anaerobes (Bacteroides, peptostrep, peptococci), either alone or w facultative bac esp E coli, Klebsiella, Aeromonas)

Question 6

What are the complications of cellulitis?

Answer 6

• Necrotizing fasciitis
• Toxic shock syndrome
• Gas gangrene
• Skin abscess

Question 7

how is cellulitis diagnosed?

Answer 7

specimens for microbiology analysis not useful in mild infection; but cultures of blood/ pus/ bullae useful in setting of moderate/ severe infection

Question 8

how is cellulitis managed?

Answer 8

Management includes elevation of affected area (gravity drainage of oedema/ inflammatory substances), hydration (prevent skin cracking), targeting predisposing factors (tinea pedis, lymphoedema, chronic venous insufficiency)

Patients with peripheral edema are predisposed to recurrent cellulitis. Support stockings, good skin hygiene, and prompt treatment of tinea pedis can prevent recurrences.

•Antimicrobial options are B-lactams, clindamycin, bactrim, tetracycline, linezolid (non B lactam agents relevant in likely MRSA infection)

Question 9

what are the differentials for cellulitis

Answer 9

Unilateral redness

1) infective
- acute necrotising soft tissue infection
- deep subacute/ chronic infection
- septic arthritis/ bursitis
2) non infective
- vascular disease
- crystal arthropathies

bilateral redness

1) infective
- bilateral true cellulitis
- infected ulcers
2) non infective
- vascular disease
- systemic inflammatory disease