John R. Tkach, M.D.
300 North Willson, Suite 203B
Bozeman, MT 59715
(406) 587-5442

Impetigo, Cellulitis, & Ecthyma Skin Infections

Patient Information Sheet

These are itchy and or painful bacterial infections of the skin. They are contagious. You get it from someone else. You can give it to others. More importantly, you can spread the infection on yourself by scratching. The germs are counting on you to do just that.

The progression is: Impetigo -> Cellulitis -> Ecthyma -> Septicemia

  1. Impetigo is an infection limited to the almost paper-thin outer living layer of growing skin cells that make up the epidermis. Two hallmarks are itching and honey crust. If a rash develops what looks like a thin layer of dried honey and becomes progressively and intensively more itchy, it has probably become infected.
  2. Cellulitis is the next deeper layer of infection going into the dermis below the epidermis.
  3. Ecthyma is an infection that is so severe it has eaten away enough skin that there is a hole there, an ulcer. This is especially important on the ankle and lower leg in the elderly. Repeated ulcers on the lower legs and ankles can also be a sign of a disorder in blood clotting.
  4. Septicemia is a spread of the infection into the blood stream where it can be disseminated all over the body. It is serious.

There are some odd variants of impetigo such as bullous (blisters) impetigo and Staphylococcal Scalded Skin Syndrome (a potentially life threatening emergency), in which the skin peels off in sheets.


Impetigo, cellulitis, and ecthyma usually are curable with antibiotic pills. Septicemia may require hospitalization and intravenous antibiotics.

There are two aspects to this problem. What is the bacterium causing the infection? What antibiotics is it sensitive to. A good way to answer these questions is to do a culture and sensitivity laboratory study. I do not mean that all cases need culture, but it is never a wrong thing to do. The reason for it is that bacteria have become more complicated and sneaky. It is harder now than it was 30 years to figure out the right treatment.

I have developed a fastidious culturing technique that I have not heard anyone else talk about using. The problem is that often the standard swab wipe method of collecting the specimen fails to grow the offending bacteria. This is especially true with Beta Strep. Infections.

I wet the sterile swab tip in thioglycolate broth, swab the infected area, and put that into the broth. Thisadds a day to the culture process, but that loss of time is offset by getting more reliable culture results.

From swabbing to identifying the best antibiotic to use takes about 4 days. While waiting for the results, we may want to take a guess and start antibiotic treatment. By guess, I mean based on the current prevalent antibiotic resistance and sensitivity patterns in our lab. It's not a wild guess. For example, as of 2009, minocycline and Bactrim or Septra were 98% likely to work for Staph aureus including MRSA, methicillin resistant staph aureus.

If you are allergic to an antibiotic, you must let me know that before we start treatment.

Topical antibiotics

Generally, antibiotic pills are the mainstay of treating impetigo. But, if you only have a small area of infection, why take a drug that is going to go through you whole body in areas that are not infected? Well, the antibiotic pills are more reliable. There may be infection in areas you do not detect yet, as in atopic dermatitis.

Two effective topical antibiotics are Bactroban and Altabax ointment. These are applied twice a day for 10 days. They are helpful for small areas of infection limited to the epidermis, impetigo. When Bactroban first came out, we were told it is impossible to Staph aureus to become resistant to it. Well, it turned out that bacteria are a lot smarter than doctors.

Do not underestimate impetigo. It is very easy for it to go unrecognized and untreated. Be suspicious if your rash is very itchy, persistent, and is not getting better with topical cortisone treatments.

The information provided in these patient information sheets is offered for general informational and educational purposes only; it is not offered as and does not constitute medical advice. In no way are any of the materials presented meant to be a substitute for professional medical care or attention by a qualified practitioner, nor should they be construed as such.

Schedule your appointment today.