Skin infections & Quinolones -4
Types of Skin Infections - Cont.
  • Impetigo
  • Impetigo is a common bacterial infection of the upper layers of the skin caused by Streptococcus pyrogenes and Staphylococcus aureus. It is highly contagious and usually treated with a topical antibiotic.

Cause of Impetigo
In industrialized countries most cases of impetigo are caused by Staphylococcus aureus, but in developing countries Streptococcus pyogenes is the main causitive agent. Mixed infections caused by both bacteria are common and result when a primary infection is invaded by the other bacteria.

Factors that Make Impetigo Worse
Impetigo tends to occur in areas of minor breaks in the skin such as insect bites, cuts, or abrasions. Impetigo can also occur in breaks in the skin caused by skin conditions such as eczema, scabies, herpes, chickenpox, or contact dermatitis.
Often people harbor the Staphylococcus bacteria inside their nose and don't even know it because it does not cause an infection inside the nose. However, direct contact with infected nasal fluid can infect other parts of the body or other people.

The following are common contributing factors:
  • Traumatized skin
  • Over-crowding
  • Poor hygiene
  • Nasal colonization with bacteria
  • Warm, humid climate or environment

Impetigo is classified as bullous or non-bullous. Both types have a distinct appearance and cause.

Non-Bullous Impetigo

More common - 70% of impetigo infections
Caused by either Streptococcus or Staphylococcus species
Hallmark of appearance is a thick "honey-colored" crust
Occurs mainly on face or limbs
Only large lesions are painful
Generally does not cause a fever
Heals without scarring

Bullous Impetigo

Less common form of impetigo
Occurs mainly in newborns and younger children
Caused by a specific sub-group of Staph. aureus
Blisters form in response to a toxin produced by the bacteria
Occurs on face, trunk, hands, and buttocks
Generally does not cause a fever
Heals without scarring

Non-bullous impetigo is treated with the topical antibiotic mupirocin applied to the lesion four times a day until the lesion is gone for three days.
Bullous impetigo and resistant non-bullous infections are treated with oral antibiotics. Penicillin and amoxicillin are not good antibiotics to use because of increasing resistance rates. Antibiotic classes that are effective include the macrolides (erythromycin, azithromycin, or clarithromycin) and the cephalosporins (cephalexin, cefprozil, or cefdinir).

How Impetigo is Diagnosed
Impetigo is often diagnosed clinically, based on the characteristic appearance. However, because impetigo can be confused with several other skin conditions, certain tests may be needed to make the diagnosis.

The most common diagnostic tests performed are a
gram stain'A gram stain is a method of identifying bacteria. A cotton swab is usually used to take a sample of infected fluid'
bacterial culture'A culture is a medical tool used to test material (pus, skin cells, blood, sputum, etc.) from an individual with a suspected infection.It is used to determine if a rash is caused by an infection, and if so, the organism that causing the infection, and possibly what medication will kill the infection.'
obtained by swabbing the base of a lesion with a cotton swab.

How to Prevent Impetigo?
The following measures may help prevent impetigo from developing:
  • Frequently wash areas of minor skin trauma with soap and water
  • Avoid overcrowded living conditions
  • People with recurrent impetigo should have the inside of the nose cultured to determine if they are a carrier of Staphylococcus aureus
  • Staph carriers should be treated with topical mupirocin inside the nose.

  • Erythrasma
  • Erythrasma is a bacterial infection caused by the bacteria Corynebacterium minutissimum. It occurs most often between the third and fourth toes, but it can also frequently be found in the groin, armpits, and under the breasts. Because of it's color and location, it's often confused with a fungal infection like jock itch.
Erythrasma is more common in the following populations:
  • Diabetics
  • Elderly
  • Overweight people
  • People in warm, moist climates

Erythrasma Appearance
Erythrasma starts as a pink to red patch with well-defined edges. This patch has a finely wrinkled appearance with a very fine scale on it. After some time, the rash fades from pink to a uniform brown color. This consistent brown color with the fine scale distinguishes it from jock itch or other fungal infections which are typically more red around the edges with thicker scaling on the edges.

Other Rashes Like Erythrasma
Even though erythrasma is often confused with jock itch, other skin conditions can look similar. These include:
  • Inverse psoriasis' is an unusual type of psoriasis that occurs in skin folds. These patches look different than other types of psoriasis. They are usually smooth, deep red, and glistening without any scale. Sometimes there is a crease in the center of the patch that may be cracked open.'

  • Tinea Versicolor
  • Intertrigo'is an inflammation (rash) of the body folds (adjacent areas of skin).An intertrigo sometimes refers to a bacterial, fungal, or viral infection that has developed at the site of broken skin due to such inflammation.'

Erythrasma Diagnosis

  • Typical appearance
  • Performing tests to help make the diagnosis & to diffrenciate between erythrasma and a fungal infection through Wood's Lamp examination on the rash. Under the UV light of a Woods Lamp, erythrasma turns a bright coral red, but fungal infections do not. Other tests that may help include:
  • Gram Stain: A way to identify bacteria from a sample of the scale. Unfortunately, this bacteria is difficult to get to stick to the slide so it requires a special technique.
  • KOH Test: This is a test used to identify fungal elements. This test might be done to confirm that there is no fungus present.
  • Skin Biopsy: A sample of tissue is removed and evaluated under a microscope. In erythrasma, the bacteria can be seen in the upper layer of the specimen.

Erythrasma Treatment
Since this is a bacterial infection, erythrasma is best treated with antibiotics, and fortunately several antibiotics fit the bill. The following are antibiotics that are typically prescribed for erythrasma:

  • Erythromycin 250 mg four times a day for 5 days
  • Clarithromycin 1gm once
  • The antifungal creams miconazole, clotrimazole and econazole, but not ketoconazole
  • Topical antibiotics like clindamycin or erythromycin twice a day for 2 weeks

  • Acrodermatitis
  • Acrodermatitis enteropathica is a skin condition peculiar to children that may be accompanied by mild symptoms of fever and malaise.
    It may also be associated with hepatitis B infection or other viral infections. The lesions appear as small coppery-red, flat-topped firm papules that appear in crops and sometime in long linear strings, often symmetric.

The cause of acrodermatitis is poorly understood, but its link with other infections is well- documented.
In Italian children, acrodermatitis is seen frequently with hepatitis B, but this link is rarely seen in the United States. In addition to hepatitis B, acrodermatitis has also been associated with Epstein-Barr virus infections (EBV, mononucleosis), cytomegalovirus, coxsackie viruses, parainfluenza virus, respiratory syncytial virus (RSV), and some live virus vaccines.

  • Generally not itchy
  • Rash or patch on skin
  • String of bumps may appear in a line
  • Rash looks the same on both sides of the body
  • Brownish-red or copper-colored patch that is firm and flat on top
  • Rash may appears on the palms and soles-it does not occur on the back, chest, or belly area
Other symptoms that may appear include:
  • Swollen abdomen
  • Swollen lymph nodes
  • Tender lymph nodes