Cellulitis

Do not put a needle through infected skin - The failure mode is seeding the epidural space. Spinal epidural abscess arrives either by direct extension from a contiguous site or by hematogenous and lymphatic spread from a remote one, and a quarter to half of cases are hematogenous — most of those from skin or soft tissue. Direct instrumentation is itself a risk factor, and diabetes, the commonest comorbidity behind cellulitis, is also the commonest risk factor for epidural abscess. A block site remote from the infection is a different conversation from a block site through it.

Decide first whether this is local or systemic - The threshold for hospitalization and parenteral therapy is two or more of: temperature above 38 degrees C, heart rate above 90, respiratory rate above 20, white count above 12,000 or below 4,000, or bands at or above 10 percent. Meeting those alongside infection is what gets called sepsis, and it turns a skin infection having an I&D into a septic patient having source control.

Rule out necrotizing fasciitis before you settle in - Fever, erythema, edema, pain out of proportion to the exam, and crepitus. Subcutaneous gas in soft tissue on CT is highly specific, but imaging must not delay the trip to the operating room. That patient is a resuscitation with an emergent debridement, not an add-on case.

Examine the limb yourself - If an extremity is involved, confirm intact sensation and palpable pulses; compartment syndrome sits on the same differential. The same exam decides tourniquet and positioning and gives you the pre-anesthetic neurologic baseline you will want if a block goes in.

Antibiotic choice tracks the host, not just the rash - Mild disease without systemic signs is covered for streptococci. Immunocompromised patients needing parenteral therapy get broad coverage — vancomycin plus piperacillin-tazobactam, or a carbapenem. Blood cultures are worth drawing when there is systemic toxicity, treatment failure, immunocompromise, an animal bite, or an immersion injury.

Cellulitis of the floor of the mouth is an airway case - Ludwig angina involves the sublingual, submental, and submandibular spaces, usually from an infected lower second or third molar, and it progresses rapidly toward obstruction. Cervicofacial cellulitis is the presentation where tracheostomy becomes the endpoint. Settle the airway plan with the surgeon in the room before anything removes spontaneous ventilation.

Know which orbital compartment - Periorbital (preseptal) cellulitis sits anterior to the orbital septum. Orbital (postseptal) cellulitis involves the muscle and fat inside the orbit and shows proptosis, chemosis, ophthalmoplegia, pain with eye movement, and reduced vision. Optic disc swelling or retinal artery thrombi on fundoscopy suggest intracranial extension. The distinction changes the urgency and changes what the surgeon is about to do.

The comorbidity is the anesthetic - Diabetes, venous insufficiency, peripheral arterial disease, and lymphedema are why this patient is in front of you. Look at glycemic control, the peripheral pulse exam, and the condition of the skin everywhere you plan to place a line.

Site vascular access away from involved skin - IV puncture sites are a listed portal for cellulitis in the first place. Keep new lines out of erythematous or edematous territory and out of a lymphedematous limb.

Positioning and edema - Elevating the affected area above heart level reduces edema, and treating the underlying cause of the edema is what prevents the next episode. Build that into how you pad and position rather than leaving it as a ward instruction.

Cellulitis is acute bacterial infection of the deep dermis and surrounding subcutaneous tissue without abscess or purulent drainage — a poorly demarcated warm, erythematous, edematous, tender area. Beta-hemolytic streptococci cause most of it, usually group A Streptococcus pyogenes, followed by methicillin-sensitive Staphylococcus aureus. Immunocompromised patients, MRSA carriers, animal-bite wounds, and diabetics draw a wider range of organisms, and diabetic foot ulcers raise the Pseudomonas question.

The skin is a barrier, so the pathogenesis is always a breach of it: skin injury, surgical incision, an IV puncture site, fissures between the toes, insect or animal bites, or another skin infection. Diabetes mellitus, venous insufficiency, peripheral arterial disease, and lymphedema all raise risk. The erythema and swelling are a cytokine and neutrophil response, and untreated the infection can reach the bloodstream and produce bacteremia, endocarditis, or osteomyelitis.