Cellulitis Bacteria and Their Characteristics


Microorganisms are the common cause of cellulitis. They are found everywhere and are also part of our body’s natural flora. Some bacteria can cause skin infection if given the opportunity to enter the body. Skin openings such as cuts, wounds, scrapes, lesions, blisters, insect or animal bites, tattoos, surgical wounds, and ulcers may be the entry point of these bacteria.

Common symptoms of cellulitis are redness, swelling and tenderness in the infected area. Read streaks may appear from the infected area and lymph node swelling may also be observed. If the cellulitis bacteria have gone deep into the skin and has infected the blood, fever and chills may also manifest as accompanying symptoms.

Cellulitis bacteria include the following:

One of the most common cellulitis bacteria are Staphylococcus aureus. These are cluster-shaped, facultatively anaerobic, gram-positive bacteria that are a part of the natural flora found in the skin and nose. Aside from humans, these bacteria are also found in cats, dogs, and horses. Once staphylococci invade the skin layers, it produces virulent enzymes. Most of the time, infection caused by these bacteria are easily traced to the source. However, there are cases when the infection will not form any abscess therefore the point of entry may not always be clear. Cure is usually with the use of penicillin, erythromycin or other antibiotic that target gram-positive bacteria.

Other common cellulitis bacteria are the Group a beta-hemolytic Streptococcus where an example is Streptococcus pyogenes. These bacteria grow in log chains and are also gram-positive. These bacteria cause a rapid progressing cellulitis and spreads laterally in the deep layers of the skin. Streptococci release hemolytic enzymes that destroy erythrocytes and disrupt the production of hemoglobin. Most often, it is an infective component of the sin’s natural flora. Streptococcus pneumoniae has also been one of the types of these bacteria to cause cellulitis. However, upon the discovery of vaccination against these bacteria, cases have been rarely reported. Penicillin and penicillin derivatives are usually used to stop this kind of infection. Erythromycin may also be given for penicillin allergic patients. However, if penicillin is used, another antibiotic that kills gram-positive bacteria should be added since erythromycin only stops bacteria multiplication.

Another type of cellulitis bacteria are the Hemophilus influenzae type B. This type of bacteria is gram-negative and non-motile. It used to rampantly cause cellulitis in children but cases of this has decreased since the advent of vaccination against flu.

Pasteurella multocida is also a gram-negative and non-motile bacterium that is highly sensitive to penicillin though some strains of this organism have developed penicillin resistance. It causes a kind of cellulitis that spreads and progresses rapidly. These cellulitis bacteria are mostly found in the upper respiratory tract of domesticated animals such as dogs and cats. Infection from this bacterium may be carried out through scratches, bites or licks from pets. Since bites from pets may bring in other microorganisms into the human skin, broad spectrum antibiotics are usually used to cure cellulitis from this bacterium.

Eikenella corrodens are gram-negative bacteria whose pathogenesis originate from the human oral cavity and may cause infection if exposed to trauma or through the spread of an infected sinus, middle ear or the oral cavity itself. It may be treated with penicillin and cephalosporins but is highly resistant to erythromycin.

These bacteria may not occur singly in cellulitis infection. Several may infect the skin at the same time so broad spectrum antibiotics that target both gram-negative and gram-positive bacteria are often used in severe cellulitis cases.