Wound Infection and Infection Control
(Content lasted reviewed - July 28, 2000)Question #301
What causes Wound Infection
Wound infection is caused by the invasion and multiplication of microorganisms in viable wound tissue, causing local tissue damage.
Question #302
How is wound infection diagnosed?
Wound infection is difficult to diagnose. The definitive method for diagnosing wound infection is through quantitative cultures of viable wound tissue or wound fluid. Wounds with greater than 105 organisms per gram of tissue or ml of fluid or with virulent organisms, such as B-hemolytic Streptococci, are considered infected. Unfortunately, these cultures are difficult to obtain and process. Growth of organisms from a simple swab culture of the wound surface is not indicative of infection. The culture specimen must be of "tissue" or "tissue" fluid, not surface fluid or exudate.
Clinical signs and symptoms are often used in the clinical setting to diagnose infection or to trigger the acquisition of wound cultures.
Question #303
What are the clinical signs and symptoms of localized infection?
The clinical signs and symptoms of local infection include increasing pain in the wound, erythema, edema, and heat of the periwound area, foul odor, and purulent drainage. These are localized signs and symptoms of infection, not systemic signs of infection.
Question #304
What are the signs and symptoms of advancing wound infection?
In addition to the localized signs identified above, elevated white blood cell count and body temperature are signs of systemic infection, such as cellulitis, osteomyelitis, and bacteremia. When localized infection is present always assess the patient for signs of systemic infection.
Question #305
Does the presence of these signs and symptoms indicate infection?
The presence of these signs and symptoms indicates that the wound may be infected. Because many of these signs (i.e., erythema, edema, and pain) are a part of the inflammatory response to injury, wound re-injury (e.g., prolonged pressure or friction) may cause these signs to present despite low organism levels. Whether or not these signs are indicative of organism invasion is a clinical judgement that must be made in light of pertinent wound variables (i.e., is there recurring wound injury?) and the number of signs and symptoms present. Purulent exudate may be the by-product of a successful response to control the growth of organisms, and, therefore, it may be present in non-infected wounds. Cloudy or milky appearing fluid under semi-occlusive or occlusive dressings is not a sign of infection.
Question #306
Is necrotic tissue a sign of infection?
Not necessarily. However, necrotic tissue does support microorganism growth and should be debrided from the wound as a first step in managing a non-healing wound. The only exception is the dry eschar on the heel, which can be left intact, but should be regularly assessed for infection.
Question #307
Does the absence of these signs and symptoms indicate the wound is NOT infected?
No. Individuals with pressure ulcers, or other types of chronic wounds, may not express the signs of infection even when their wound has significant numbers of microorganisms because they are unable to mount an adequate inflammatory response. If the ulcer does not contain necrotic tissue, the AHCPR guideline on pressure ulcer treatment recommends treating a pressure ulcer that does not exhibit signs of healing with topical antibiotics. If the ulcer does not respond within two weeks, the AHCPR guideline recommends the wound be quantitatively cultured.
Wound infection is difficult to diagnose. The definitive method for diagnosing wound infection is through quantitative cultures of viable wound tissue or wound fluid. Wounds with greater than 105 organisms per gram of tissue or ml of fluid or with virulent organisms, such as B-hemolytic Streptococci, are considered infected. Unfortunately, these cultures are difficult to obtain and process. Growth of organisms from a simple swab culture of the wound surface is not indicative of infection. The culture specimen must be of "tissue" or "tissue" fluid, not surface fluid or exudate. Clinical signs and symptoms are often used in the clinical setting to diagnose infection or to trigger the acquisition of wound cultures.
Question #303
What are the clinical signs and symptoms of localized infection?
The clinical signs and symptoms of local infection include increasing pain in the wound, erythema, edema, and heat of the periwound area, foul odor, and purulent drainage. These are localized signs and symptoms of infection, not systemic signs of infection.
Question #304
What are the signs and symptoms of advancing wound infection?
In addition to the localized signs identified above, elevated white blood cell count and body temperature are signs of systemic infection, such as cellulitis, osteomyelitis, and bacteremia. When localized infection is present always assess the patient for signs of systemic infection.
Question #305
Does the presence of these signs and symptoms indicate infection?
The presence of these signs and symptoms indicates that the wound may be infected. Because many of these signs (i.e., erythema, edema, and pain) are a part of the inflammatory response to injury, wound re-injury (e.g., prolonged pressure or friction) may cause these signs to present despite low organism levels. Whether or not these signs are indicative of organism invasion is a clinical judgement that must be made in light of pertinent wound variables (i.e., is there recurring wound injury?) and the number of signs and symptoms present. Purulent exudate may be the by-product of a successful response to control the growth of organisms, and, therefore, it may be present in non-infected wounds. Cloudy or milky appearing fluid under semi-occlusive or occlusive dressings is not a sign of infection.
Question #306
Is necrotic tissue a sign of infection?
Not necessarily. However, necrotic tissue does support microorganism growth and should be debrided from the wound as a first step in managing a non-healing wound. The only exception is the dry eschar on the heel, which can be left intact, but should be regularly assessed for infection.
Question #307
Does the absence of these signs and symptoms indicate the wound is NOT infected?
No. Individuals with pressure ulcers, or other types of chronic wounds, may not express the signs of infection even when their wound has significant numbers of microorganisms because they are unable to mount an adequate inflammatory response. If the ulcer does not contain necrotic tissue, the AHCPR guideline on pressure ulcer treatment recommends treating a pressure ulcer that does not exhibit signs of healing with topical antibiotics. If the ulcer does not respond within two weeks, the AHCPR guideline recommends the wound be quantitatively cultured.
In addition to the localized signs identified above, elevated white blood cell count and body temperature are signs of systemic infection, such as cellulitis, osteomyelitis, and bacteremia. When localized infection is present always assess the patient for signs of systemic infection.
Question #305
Does the presence of these signs and symptoms indicate infection?
The presence of these signs and symptoms indicates that the wound may be infected. Because many of these signs (i.e., erythema, edema, and pain) are a part of the inflammatory response to injury, wound re-injury (e.g., prolonged pressure or friction) may cause these signs to present despite low organism levels. Whether or not these signs are indicative of organism invasion is a clinical judgement that must be made in light of pertinent wound variables (i.e., is there recurring wound injury?) and the number of signs and symptoms present. Purulent exudate may be the by-product of a successful response to control the growth of organisms, and, therefore, it may be present in non-infected wounds. Cloudy or milky appearing fluid under semi-occlusive or occlusive dressings is not a sign of infection.
Question #306
Is necrotic tissue a sign of infection?
Not necessarily. However, necrotic tissue does support microorganism growth and should be debrided from the wound as a first step in managing a non-healing wound. The only exception is the dry eschar on the heel, which can be left intact, but should be regularly assessed for infection.
Question #307
Does the absence of these signs and symptoms indicate the wound is NOT infected?
No. Individuals with pressure ulcers, or other types of chronic wounds, may not express the signs of infection even when their wound has significant numbers of microorganisms because they are unable to mount an adequate inflammatory response. If the ulcer does not contain necrotic tissue, the AHCPR guideline on pressure ulcer treatment recommends treating a pressure ulcer that does not exhibit signs of healing with topical antibiotics. If the ulcer does not respond within two weeks, the AHCPR guideline recommends the wound be quantitatively cultured.
Not necessarily. However, necrotic tissue does support microorganism growth and should be debrided from the wound as a first step in managing a non-healing wound. The only exception is the dry eschar on the heel, which can be left intact, but should be regularly assessed for infection.