Cellulitis is usually caused by a bacterial infection.The bacteria can infect the deeper layers of your skin if it's broken, for example, because of an insect bite or cut, or if it's cracked and dry.Sometimes the break in the skin is too small to notice.You cannot catch cellulitis from another person, as it affects the deeper layers of the skin.You're more at risk of cellulitis if you:have poor circulation in your arms, legs, hands or feet, for example, because you're overweightfind it difficult to move aroundhave a weakened immune system, for example, because of chemotherapy treatment or diabeteshave , which causes fluid build-up under the skininject drugshave a wound from surgeryhave had cellulitis beforePeople who are more at risk of cellulitis should treat promptly., Cellulitis is a type of infection that affects the skin and the tissue underneath. The bacteria, most commonly Group A Streptococcal bacteria, enter the skin through an opening, such as a cut, scrape, burn, or surgical incision. It can even happen through a bug bite or sting. Cellulitis can trigger sepsis for some., Conditions such as cellulitis (inflammation of your skin’s connective tissue). Is sepsis contagious? Sepsis itself isn’t contagious — you can’t spread it to other people. But you can spread the infections that can cause sepsis..