Cochin Cardiac Club

Health Blog by Dr.Uday Nair


Cellulitis is a skin infection caused by bacteria. Normally, your skin helps protect you from infection. But if you have a cut, sore, or insect bite, bacteria can get into the skin and spread to deeper tissues. If it is not treated with antibiotics, the infection can spread to the blood or lymph nodes. This can be deadly.

Some people can get cellulitis without having a break in the skin. These include older adults and people who have diabetes or a weak immune system. These people are also more likely to develop dangerous problems from cellulitis. And they are more likely to get cellulitis again.


The skin is a good barrier against infection. However, a break in the skin from a cut, skin ulcer, injection, athlete's foot, scratch, etc, is a way in which bacteria (germs) can get into and under the skin. A tiny cut is all that is needed to allow bacteria in.

We all have some bacteria that live on our skin which normally do not cause any problems. However, if your skin is damaged or broken in some way, the bacteria can get in. The bacteria may then multiply and spread along under the skin surface to cause an infection. A cut, graze, etc, is found in many cases to be the root cause. However, sometimes the infection occurs for no apparent reason with no break in the skin found. Various different types of bacteria can cause cellulitis.

Signs and symptoms

Nonpurulent cellulitis is associated with the 4 cardinal signs of infection, as follows:
  • Erythema
  • Pain
  • Swelling
  • Warmth
Physical examination findings that suggest the most likely pathogen include the following:
  • Skin infection without underlying drainage, penetrating trauma, eschar, or abscess is most likely caused by streptococci; Staphylococcus aureus,often community-acquired MRSA, is the most likely pathogen when these factors are present.
  • Violaceous color and bullae suggest more serious or systemic infection with organisms such as Vibrio vulnificus or Streptococcus pneumoniae
The following findings suggest severe infection:
  • Malaise, chills, fever, and toxicity
  • Lymphangitic spread (red lines streaking away from the area of infection)
  • Circumferential cellulitis
  • Pain disproportionate to examination findings
Indications for emergent surgical evaluation are as follows :
  • Violaceous bullae
  • Cutaneous hemorrhage
  • Skin sloughing
  • Skin anesthesia
  • Rapid progression
  • Gas in the tissue

Diagnosis is usually fairly straightforward and does not generally require any complicated tests. A GP (general practitioner, primary care physician) can do this. The doctor will examine the patient and assess the symptoms. The number of cases where Lyme disease has been misdiagnosed as staph- or step-induced cellulitis is growing. 

It is important to discard the possibility that some other condition may have caused the symptoms, such as varicose eczema

The doctor may take a swab (sample) if there is an open wound. This will help him/her find out what type of bacteria it is. 


Cellulitis treatment usually is a prescription oral antibiotic. Within three days of starting an antibiotic, let your doctor know whether the infection is responding to treatment. You'll need to take the antibiotic for up to 14 days. In most cases, signs and symptoms of cellulitis disappear after a few days. If they don't clear up, if they're extensive or if you have a high fever, you may need to be hospitalized and receive antibiotics through your veins (intravenously).
Usually, doctors prescribe a drug that's effective against both streptococci and staphylococci. Your doctor will choose an antibiotic based on your circumstances.
No matter what type of antibiotic your doctor prescribes, it's important that you take the medication as directed and that you finish the entire course of medication, even if you start feeling better.
Your doctor also might recommend elevating the affected area, which may speed recovery.
After treatment the patient needs to come back for a follow-up so that the doctor can confirm that the treatment has worked.

Points to remember

  • Cellulitis is a spreading, acute inflammation of the dermis and subcutaneous tissue, sometimes involving muscle. Hallmarks are erythema, edema, tenderness, and warmth
  • Risk factors include diabetes mellitus (type 1 and type 2), immunocompromised state, alcoholism, intravenous drug abuse, and a prior history of cellulitis. A history of surgery resulting in disrupted lymphatic drainage predisposes to recurrent episodes (eg, saphenous vein harvesting for coronary artery bypass grafting or mastectomy and axillary node dissection)
  • The infectious agent is most frequently Streptococcus pyogenes orStaphylococcus aureus
  • First-line therapy includes oral antibiotics with good coverage of Gram-positive organisms
  • Outpatients placed on oral antibiotic therapy should be re-evaluated 24 to 48 hours after starting therapy to assess response to therapy
  • Suspected necrotizing infection, deep or quickly spreading infection (particularly on the face and hands), and orbital cellulitis require referral for further investigation and treatment
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