Erysipelas and Cellulitis Flashcards
What is the difference beween erysipelas and cellulitis?
Both usually present with the classic signs of inflammation, dolor(pain), calor(heat), rubor(erythema), and tumor (swelling).
Erysipelas affects the superficial dermis, including the superficial lymphatic system. Erysipelas (the actual redness of the infection) tends to be sharply demarcated and slightly raised and on the face and extremities.
Cellulitis however involves the deeper reticular dermis and subcutaneous fat. Cellulitis usually has diffuse borders and tends to be redder in the center of the infection with that redness decreasing as the border of the infection approaches.
Cellulitis can also include dilated and edematous skin (secondary to involvement of the lymphatic system) and bullae formation. It is usually on the lower extremities but can occur anywhere.
Describe when erysipelas and cellulitis typically occur?
These infections occur when bacteria breach the surface of the skin, especially in patients with fragile skin or decreased local host defenses from such conditions as obesity, previous trauma (including surgery), prior episodes of cellulitis, and edema from venous insufficiency or lymphedema. Often the “focus” of the infection is obvious, such as trauma, ulceration, and preexisting skin inflammation, but many times the breaks in the skin are small and clinically unapparent.
Why might cultures taken from needle aspiration or biopsy not be done? What are about blood culture?
When should cultures be considered?
- Usually, cultures taken from needle aspiration or biopsy yield inconclusive results, so they should probably not be done. The yield for a blood culture can be less than 5% so in typical cellulitis cases, cultures of any kind do not need to be completed.
- An exception to this rule is that it should be considered in those with, malignancy on chemotherapy, severe systemic features (such as high fever and hypotension), patients with neutropenia, severe cell-mediated immunodeficiency, traumatic injuries, and animal bites. Blood cultures should be obtained and cultures of skin biopsy or aspirate in this population.
Which two bacteria should be covered in erysipelas and cellulitis?
Group A Streptococci (Strep pyogenes)
Staph aureus
The microbiology of erysipelas and cellulitis is contentious. Most clinician assume that erysipelas is caused by group A streptococci (Streptococcus pyogenes), the same is true with cellulitis with Staph aureus a less common cause. Staph aureus can be seen in those with traumatic wounds, open wounds, or drug-injection sites. Microbiologic studies have not been able to definitely prove causative agents. As a result, most therapy is empiric covering the pathogens mentioned above.
What types of agents (and examples) should non-purulent cellulitis with out systemic signs be treated with?
Antistreptococcal agents such as cephalexin, cloxacillin, penicillin VK, amoxicillin/clavulanate, or, in cases of penicillin allergy, clindamycin. Luckily, most of these agents also cover Staphylococcus as well, the exception being Pen VK.
Does Pen VK cover Staph Aureus?
NO!
Presence of systemic symptoms such as: temperature greater than 38°C or less than 36°C, heart rate greater than 90/min, respiratory rate greater than 20/min, or white blood cell count greaterthan12 000 cells or less than 4000 cells/µL, make things more complicated.
In Non-Puruluent Cellulitis:
What do we do if only one of the above is present (Oral or IV)?
What do we do if one or more of the above is present? (Oral or IV)?
If they have one of these the cellulitis is considered moderate (still non-purulent) where oral therapy is acceptable.
If 2 or more of the above symptoms are present or they have failed oral therapy, the cellulitis is considered severe and usually IV antibiotics such as cefazolin, ceftriaxone, penicillin G, or, in cases of penicillin allergy, clindamycin is needed.
What bacteria is typically implicated if it is puruluent cellulitis?
Which antibiotics wouldn’t be used?
S. Aureus!
Penicillin
If the cellulitis is purulent (erysipelas is usually not purulent), then Staph aureus now becomes part of the problem. It follows the same for non-purulent from a severity perspective. The only change is in therapy. You would not use penicillin VK or penicillin G but cloxacillin instead. Long story short, you will probably not see a lot of penicillin used for erysipelas or cellulitis. In the real world, most clinicians will err on the side of caution and provide an antimicrobial that covers off staphylococcus.
What situations do we worry about MRSA?
MRSA should be considered for purulent infections in known high risk populations, such as athletes, children, men who have sex with men, prisoners, military recruits, residents of long-term care facilities, individuals with previous MRSA exposure, and intravenous drug users.
What antibiotics are used for MRSA cellulitis?
Typical antibiotics used include intravenous drugs,* (vancomycin, daptomycin, or linezolid) or *
oral therapy with doxycycline, clindamycin, or SMX-TMP.
If you need both strep and MRSA coverage, then clindamycin alone or combining either** SMX-TMP or doxycycline with a β-lactam (e.g., penicillin, cephalexin, or amoxicillin). Can be done**. Vancomycin will cover off MRSA when IV is needed.
How long should cellulitis be treated for?
The duration of treatment should always be based on response. Treatment durations for outpatient cellulitis/erysipelas range from 5 to 10 days while in the immunocompromised patients may require 7 to 14 days. It is probably best to reassess therapy at 24-48 hours of treatment looking for improvement in pain, redness, swelling, or warmth.
Basically, upon diagnosis, you use a marker and draw a line around the cellulitis. If in a day or two, it is retreating from the line, things are going well. If the cellulitis grows beyond the line, then adjusting antibiotic selection should be considered for possible resistant pathogens such as MRSA or alternative diagnoses should be sought as many syndromes can pass for a cellulitis or erysipelas
What is the rate of recurrence of cellulitis?
about 8%–20% in a year
What are local risk factors for recurrenence of cellulitis?
The infection usually occurs in the same area as the previous episode. Edema, (especially lymphedema) and other local risk factors such as venous insufficiency, prior trauma (including surgery) to the area, and feet fungal infections or foot abnormalities (anatomical, toe webs space abnormalities) can increase the possibility of recurrences.
Other predisposing conditions include obesity, tobacco use, a history of cancer, and homelessness
What are some preventative measure that could be done?
Regular foot examinations; dry skin care; treatment of fungal infections of the feet/toe, or other chronic dermatoses; use of support stockings and other tools for lymphedema control; weight loss; stop smoking; and intensive wound care for ulceration can help prevent primary and recurrent cellulitis. You can even volunteer at a homeless shelter to help check people’s feet!
What is the word about prophylactic antibiotics?
Prophylactic antibiotics, for recurrent cellulitis is controversial, but could be a possibility in patients with 3 to 4 episodes of cellulitis per year who are in control of risk factors.
Prophylaxis could be cost-effective if it works, but this has to be balanced against allergy development, drug reaction, drug resistance, and
Clostridioides difficile infection. Proposed regimens include oral penicillin 250 mg or 1 g twice daily, erythromycin 250 mg twice daily, cloxacillin 500 mg orally twice daily, clindamycin 150 mg orally every day, and intramuscular benzathine penicillin 1.2 million U/month for durations from anywhere of 4 to 52 weeks.
Decolonization of the causative bacteria is generally not successful.
