SKIN INFECTIONS

SKIN INFECTIONS 

SKIN INFECTIONS:
Skin infections are characterized by lesions and rashes but they don’t necessarily be just skin infections and many times are manifestations of some disease of internal organs.
Rashes on the skin are called EXANTHEM and those present on the mucous membrane are called ENANTHEM.

BASED ON THEIR APPEARANCE,  following are the types of skin lesion:
VESICLES are small fluid-filled lesions.
When vesicles grow in size of greater than 1 cm diameter then they are called BULLA.
Flat reddened lesions are called MACULES.
When macules are raised then they are called PAPULES.
When papules are filled with pus ,then they are called PUSTULES.

STAPHYLOCOCCI & STREPTOCOCCI are frequent causes of skin infections. Actually, they are well adapted to living in conditions present on skin ,but at the same time are harmful because of enzymes and toxins they produce which makes them pathogenic. Both are gram-positive bacteria and are treated by PENICILLIN antibiotics.

STAPHYLOCOCCAL SKIN INFECTIONS :
For all clinical purposes, staphylococci are divided in to COAGULASE-POSITIVE & COAGULASE -NEGATIVE based on their ability to produce coagulase.

STAPHYLOCOCCUS EPIDERMIDIS-it is a coagulase-negative bacteria and forms 90 % of the normal microbiota of skin. They become pathogenic on getting access to broken skin.

STAPHYLOCOCCUS AUREUS-IT is coagulase positive and forms fibrin clots in blood which protects it from phagocytes and other immune defenses.
Pathogenicity has been seen to be highly correlated to the ability of coagulase production

S.AUREUS also becomes a problem in hospital infections because of extreme use of antibiotics there which makes them resistant and able to cause infection.

Even if the skin is not broken ,then S.AUREUS can enter the body through NASAL PASSAGES & HAIR FOLLICLES.

ĎEPENDING ON IT'S SEVERITY ,INFECTION OF HAIR FOLLICLES IS OF VARIOUS TYPES:

 Simple  infection of hair follicles is called FOLLICULITIS.(it occur as pimples).
When folliculitis gets more serious then it is called FURUNCLE or BOIL. Furuncle is a type of abscess, which contains pus surrounded by inflamed tissues. It is generally difficult to treat by antibiotics as they cant penetrate it. So,draining pus from the abscess is needed before  taking antibiotics for the treatment to be successful.

When furuncle is not treated well then ,neighbouring tissues can be invaded giving rise to CARBUNCLE; which is a hard and deep inflammation of tissues under the skin.

●Infected follicles of an eyelash is called a STY.

IMPETIGO OF THE NEWBORN- it occurs in newborn babies and symptoms are visible as vesicles on the skin. It is treated by HEXACHLOROPHENE  containing skin lotions.

■staphylococcal infections often infect underlying tissues and  enter the bllod stream where they produce toxins and cause diseases, two of them are discussed below:

●SCALDED SKIN SYNDROME - it is a manifestation of EXFOLIATIVE toxin.It first appears as a lesion sround nose and mouth and rapidly develops and spreads as a bright red area .
Within 48 hours, the skin starts peeling off when touched. It is frequent in kids under 2 years age and  vigorous antibiotic therapy is done to protect them.

●TOXIC SHOCK SYNDROME- it is a life-threatening condition  and it's symptoms are fever,rashes ,vomiting  followed by shock and sometimes organ failure esp. Of kidneys.

It was first discovered in case of staphylococcal growth which occured due to use of a new type of highly adsorbent vaginal tampon.
It is especially high for  cases in which tampons remain in place for too long.
Symptoms are caused due to TSST-1 toxin which forms at the growth site and  circulates in the blood stream.
Nonmenstrual TSS occurs in cases of  women who have recently given birth and nasal surgery because adsorbent packing is used in this case