Cellulitis is a frequent medical skin infection caused by bacteria that can spread through the skin and connective tissues.

The disease is an acute, painful and potentially severe infection of the skin and subcutaneous tissues.

The borders of cellulitis are poorly demarcated.

Erysipelas

This is essentially a superficial form of cellulitis that involves the upper subcutaneous tissues and dermis.

This makes it very difficult to differentiate cellulitis from erysipelas medically.

In erysipelas, borders of infection are clearly demarcated.

The appearance is that of a fiery red rash that can be painful.

Erysipelas is also called St Anthony's fire.

This name is from the Egyptian healer of the middle Ages who had been able to cure it.

What are the causes of Cellulitis?

Risk factors for infection

They are more frequent and more severe in patients with underlying diseases such as:

1. Diabetes,

2. Cancer

3. Immunodeficiency

Other risk factors for cellulitis are:

1. Cracks or peeling skin between the toes

2. Venous insufficiency or history of peripheral vascular disease

3. Injury or trauma with a break in the skin or skin wounds or abrasions

4. Insect bites and stings, animal bites, or human bites

5. Ulcers from certain diseases including diabetes and vascular disease

6. Use of corticosteroid medications or medications that suppress the immune system

7. Wound from a recent surgery

8. Previous erysipelas or cellulitis.

9. Elderly age.

10. Alcoholism

11. Intravenous drug use.

12. Lymph edema.

13. Obesity.

14. Inflammatory dermatoses.

15. Pregnancy.

Causative organisms

Cellulitis

Majority of infections that involve intact skin are believed to caused by streptococci, although many other micro-organisms may be responsible if the skin integrity is compromised

Infrequently, Gram-negative bacteria, anaerobes or fungi may produce cellulitis.

These organisms are more frequent causes in children, people with immuno-compromised patients and in diabetes.

Cellulitis happening around surgical wounds less than 24 hours post-operatively may result from group A beta-hemolytic streptococci or Clostridium perfringens.

The latter produces gas gangrene, resulting in crepitus on examination.

Erysipelas

Majority of infections are with group A streptococci but Streptococcus pneumoniae, Klebsiella pneumoniae, Yersinia enterocolitica, Hemophilus influenzae type b, and Moraxella spp. have been found.

Rarer causative organisms

Infrequently, cellulitis or erysipelas may be produced by other organisms:

1. H. influenzae type b - in children less than 6 years of age.

2. Pasteurella multocida, Streptococcus anginosus (formerly known as Streptococcus milleri), and

3. Capnocytophaga canimorsus - following cat or dog bites.

4. Vibrio vulnificus, Aeromonas hydrophila - following sea or fresh-water exposure.

5. Erysipelothrix rhusiopathiae - in butchers, vets or fish handlers.

6. Mycobacterium marinum - in aquarium keepers.

It is therefore important to find out the patients' occupations in poorly healing infections.

The most frequent causative organisms are Streptococcus or Staphylococcus species but they can be due to a wide range of both aerobic and anaerobic bacteria

Normal skin has many forms of bacteria living on it.

When there is a break in the skin, these bacteria can produce a skin infection.

The most frequent locations of cellulitis were the legs and toes, followed by the feet, hands, face,...