BACTERIAL SKIN AND WOUND INFECTIONS
Wounds may occur following: surgery, trauma or injections
Wound infections may occur mainly after surgical procedures
Wound sepsis is the result of cross infection from human sources and from other outside sources.
Many bacteria are associated with wound infection.
The normal flora may also cause infection.
The most common bacteria of the skin are: staphylococci, and various streptococci, Sarcina spp, anaerobic Diphtheroids, gram negative rods and others
The nutrition is derived from 1. sweat, 2. aminoacids and peptides from the skin, 3. fatty acids from the sebaceous glands of the skin.
1. The climate: The temperature and humidity
2. The effect of free fatty acids
3. Other bacterial inhibitors
4. Maintenance of the flora by products of skin secretions
1. Intact skin. Normal uninterrupted skin provides protection against invasion by bacteria
2. Lysozyme in sweat: The enzyme lysozyme provides protection against gram positive bacteria by lysing the cell wall.
3. Ig A antibodies in the sweat and secretions provide first line of defense against infection
4. Inhibitors like unsaturated fatty acids provide protection against bacteria
5. Bacteriocins produced by the normal flora prevent the establishment of other bacteria
he following factors help the organisms tosurvive and produce the infections
1. Extremes of age
2. Diabetes mellitus
3. Steroid therapy
6. Immunocompromised individual
7. Presence of remote infection at the time of surgery
1. Use of un sterile instruments
2. Surgeons hands / from health workers
3. Air / Hospital environments
1. Wound contamination from the patient source: from the normal flora
2. Wound penetrating through structures containing normal flora
3. Surgical procedures involving mucous membranes harboring normal flora
4. Patients carrying pathogens in their nose, throat, axilla etc.
Member of enterobacteriaceae
Gas gangrene organisms
Wounds may occur following: surgery, trauma or injections. Wound infections may occur mainly after surgical procedures. Wound sepsis is the result of cross infection from human sources and from other outside sources.
1. Organisms enter through the skin, multiply there and pro-duce the disease in the skin. For example, impetigo, abscess and cellu-litis are caused by Staphylococcus aureus and Streptococcus pyogenes. As soon as the organisms enter the skin they multiple and produce various toxins that kill the cells and produce cellulites. Further damage leads to necrosis and ulcer formation.
2. Organisms multiply in the skin and produce disease in inter-nal organs. For example some group A streptococci multiply in the skin and produce disease known as acute glomerulo nephritis causing damage to the kidneys. Some times C.diphtheriae may multiply in the skin and affect the heart due to the toxin.
3. Some times organism may multiply in the skin and produce the toxin which affect the CNS and the effects are seen. In the case of Clostridium tetani, convulsions and paralysis occur due to the pro-duction of a powerful toxin
Pus and wound swabs are cultured for the aerobic and anaero-bic organisms and are identified using appropriate biochemical tests.