| Bacteria and other microorganisms |
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Skin and Soft Tissue Infection
Many important diseases manifest themselves such symptoms as rashes, vesicles, and other lesions that mainly affect the
skin
Bacterial Diseases of the skin
Two genera of bacteria Staphylococcus and Streptococcus are frequently causes of skin related diseases.
Cellulitis
Definition:
An acute noncontagious inflammation of the connective tissue of the skin, resulting from staphylococcus, streptococcus, or
other bacterial infection (aerobic gram negative bacilli eg. Escherichia coli, pseudompnas aeruginosa, Pasteurella multocida,
Aerominas hydrophila, Vibrio Vulnificus).
Causes, incidence, and risk factors:
The skin normally has many types of bacteria on it, but intact skin is an effective barrier that keeps bacteria from entering
and growing within the body. When there is a break in the skin, bacteria can enter the body and grow there, causing
infection and tissue reaction to injury (inflammation). The skin tissues in the infected area become red, hot, and painful.
Cellulitis is most common on the face and lower legs although skin on other areas of the body may be involved.
Risk factors for cellulitis include insect bites and stings, animal bite, or human bite; injury or trauma with a break in the skin
(skin wounds).
Lymphadenitis and lymphangitis
Alternative names:
infection - lymph glands; lymph gland infection
Definition:
An infection of the lymph glands and lymph channels.
Causes, incidence, and risk factors:
The lymphatic system is a network of vessels (channels), glands (nodes) and organs. It functions as part of the immune
system to protect against and fight infection, inflammation, and cancers. It also functions in the transport of fluids, fats,
proteins, and other substances within the body. The lymph glands, or lymph nodes, are small structures that filter the lymph
fluid. There are many white blood cells in the lymph nodes to help fight infection.
Lymphadenitis and lymphangitis are common complications of bacterial infections. Lymphadenitis involves inflammation of
the lymph glands. This may occur if the glands are overwhelmed by bacteria, virus, fungi, or other organisms and infection
develops within the glands. It may also occur as a result of circulating cancer cells or other inflammatory conditions. The
location of the affected gland(s) is usually associated with the site of the underlying infection, tumor, or inflammation. It
commonly is a result of a cellulitis or other bacteria infection (usually infection by streptococci or staphylococci).
Lymphangitis involves the lymph vessels/channels, with inflammation of the channel and resultant pain and systemic and
localized symptoms. It commonly results from an acute streptococcal or staphylococcal infection, such as from an insect or
animal bite or sting.
The infection of lymphadenitis and lymphangitis may include formation of abscesses and cellulitis. It may progress rapidly,
spread to the bloodstream within hours, and may be fatal. Lymphangitis may resemble thrombophlebitis.
Symptoms:
LYMPHADENITIS
lymph nodes may be swollen, tender, and hard
lymph nodes feel smooth or irregular to touch, or soft and "rubbery" (fluctuant) if an abscess has formed
the skin over a node may be reddened and hot
LYMPHANGITIS
Erysipelas
Alternative names:
cellulitis - streptococcal; facial infection; infection - face
Definition:
An acute inflammation of the connective tissues of the skin, usually on the face, caused by infection with streptococcus
bacteria.
Causes, incidence, and risk factors:
Erysipelas is a severe form of cellulitis in which the infection is caused by streptococcus (strep) or occasionally with
staphylococcus (staph), both of which are normal skin bacteria. Erysipelas is uncommon, affecting 1 out of 10,000 people.
The skin normally has many types of bacteria on it, but intact skin is an effective barrier that keeps bacteria from entering
and growing within the body. When there is a break in the skin, bacteria can enter the body and grow there, causing
inflammation and infection.
The inflammation of erysipelas occurs most commonly on the cheeks. The infection is characterized by systemic illness,
pain, and a fever. A bright red spot appears, often near the tip of the nose. It quickly spreads to the cheeks and tends to
enlarge rapidly. It may follow a respiratory infection such as a cold, when the nose may become raw or chapped.
Abscess
Definition:
A localized collection of pus in any part of the body that is the result of the displacement or disintegration of tissue.
Causes, incidence, and risk factors:
Abscesses occur when a small area of tissue becomes infected and the body is able to "wall off" the infection and keep it
from spreading. White blood cells, the body's defense against some types of infection, migrate through the walls of the
blood vessels in the area of the infection and collect within the damaged tissue. During this process "pus" forms which is an
accumulation of fluid, living and dead white blood cells, dead (necrotic) tissue, and bacteria or other foreign invaders or
materials.
Abscesses can form in almost every part of the body and may be caused by bacteria, parasites, and foreign materials.
Abscesses in the skin are readily visible, red, raised and painful. Abscesses in other areas of the body may not be obvious
but if they involve vital organs they may cause significant damage.
Necrotizing Subcutaneous Infection
Alternative names:
Flesh-eating bacteria; fasciitis - necrotizing; infection - necrotizing subcutaneous; subcutaneous infection - bacterial;
necrotizing fasciitis
Definition:
A type of tissue infection involving skin, subcutaneous fat, the muscle sheath (fascia) and the muscle. It causes gangrenous
changes, tissue death, systemic disease, and frequently death.
Causes, incidence, and risk factors:
Necrotizing subcutaneous infection or fasciitis can be caused by a variety of bacteria including oxygen-using bacteria
(aerobic) or oxygen-avoiding bacteria (anaerobic). A very severe and usually fatal fasciitis is caused by a virulent specie of
streptococcus that is often referred to as the Flesh-eating bacteria by the press.
This type of infection develops when bacteria enter the body, usually through a minor skin injury or abrasion. The bacteria
begin to grow and release toxins that:
Folliculitis
Alternative names:
barber's itch; pseudofolliculitis barbae; tinea barbae
Definition:
A group of superficial common infections of the hair follicle.
Causes, incidence, and risk factors:
The usual cause is the bacteria Staphylococcus (staph) or by a fungus. It may occur anywhere on the skin, as a result of
injury or damage to the hair follicle caused by friction from clothing, by blockage of the follicle, or by such things as shaving.
Barber's itch is a staph infection of the hair follicles in the bearded area of the face, usually the upper lip. Shaving
aggravates the condition. Tinea barbae is similar to barber's itch, but the infection is caused by a fungus.
Pseudofolliculitis barbae is a disorder occurring primarily in Black men where the hair of the beard grows into the adjacent
hair follicle and forms a small curled mass (aggregation of cells) within the follicle. This becomes chronically infected with any
of a variety of bacteria. It is aggravated by shaving.
Carbunculosis and furunculosis are 2 other forms of folliculitis caused by infection with staph. They may occur anywhere on
the body.
Furuncle
Alternative names:
infection - hair follicle; hair follicle infection; boils
Definition:
An infection of the hair follicles. Also see carbunculosis.
Causes, incidence, and risk factors:
A furuncle (boil) is a skin infection involving the entire hair follicle and the adjacent subcutaneous tissue. Almost everyone
experiences boils at some time. Staph bacteria are normally found on the skin surface. Damage to the hair follicle allows the
bacteria to enter deeper into the tissues of the hair follicle and the subcutaneous tissue. Furuncles may occur in the hair
follicles anywhere on the body, but they are most common on the face, neck, armpit, buttocks, and thighs.
Furuncles are generally caused by Staphylococcus aureus but may be caused by other bacteria or fungi. They may begin as a
tender red subcutaneous nodule but ultimately become fluctuant (feel like a water-filled balloon). A furuncle may drain
spontaneously, producing pus and a solid core. More often they are opened by the individual, a parent, or a physician.
Furuncles can be single or multiple. Some people have recurrent bouts with abscesses and little success at preventing them.
Furuncles can be very painful if they occur in areas like the ear canal or nose. Furuncles by the nose should be treated by a
health care provider. Furuncles that develop close together may expand and join together, a condition called carbunculosis.
Note: Itching (pruritus) of the skin may occur before the skin lesions develop.
Carbunculosis
Alternative names:
staph skin infection; skin infection - staphylococcal; infection - skin - staph; carbuncles
Definition:
A local staphylococcal skin infection involving deep subcutaneous fascia.
Causes, incidence, and risk factors:
A carbuncle consists of several furuncles (see furuncle) that develop close together. They expand and join together to form
a larger mass (aggregation of cells) with multiple drainage points. This mass may be deeper beneath the skin surface than
simple furuncles. They develop slowly, and may be so deep that they do not drain on their own. Carbuncles may develop
anywhere, but they are most common on the back and the nape of the neck. Carbuncles are less common than boils. Men
are more prone to carbuncles than women.
Staph skin infections are contagious. They may spread to other areas of the body, and may spread to other people. It is not
uncommon for several family members to be affected at the same time. Poor hygiene, run-down physical condition, friction
from clothing or shaving, and similar factors may make them more likely. Diabetics and people with suppressed immune
systems are more prone to development of staph skin infections, as are people with dermatitis, pernicious anemia, and
other disorders. Often, however, no direct cause is found for furunculosis or carbunculosis.
Erythema multiforme
Alternative names:
Stevens-Johnson syndrome; toxic epidermal necrolysis; Lyell's syndrome
Definition:
A skin disorder resulting from an allergic reaction.
Causes, incidence, and risk factors:
Erythema multiforme is a type of hypersensitivity (allergic) reaction that occurs in response to medications, infections, or
illness. Medications associated with erythema multiforme include sulfonamides, penicillins, barbiturates, and phenytoin.
Associated infections include herpes simplex and mycoplasma infections.
The exact cause is unknown. The disorder is believed to involve damage to the blood vessels of the skin with subsequent
damage to skin tissues. Approximately 90% of erythema multiforme cases are associated with herpes simplex or Mycoplasma
infections. The disorder occurs primarily in children and young adults.
Erythema multiforme may present with a classic skin lesion with or without systemic (whole body) symptoms. In Stevens-
Johnson syndrome, the systemic symptoms are severe and the lesions are extensive, involving multiple body areas
(especially the mucous membranes). Toxic epidermal necrolysis (TEN syndrome, or Lyell's syndrome) involves multiple large
blisters (bullae) that coalesce, followed by sloughing of all or most of the skin and mucous membranes.
Many important diseases manifest themselves such symptoms as rashes, vesicles, and other lesions that mainly affect the
skin
Bacterial Diseases of the skin
Two genera of bacteria Staphylococcus and Streptococcus are frequently causes of skin related diseases.
Cellulitis
Definition:
An acute noncontagious inflammation of the connective tissue of the skin, resulting from staphylococcus, streptococcus, or
other bacterial infection (aerobic gram negative bacilli eg. Escherichia coli, pseudompnas aeruginosa, Pasteurella multocida,
Aerominas hydrophila, Vibrio Vulnificus).
Causes, incidence, and risk factors:
The skin normally has many types of bacteria on it, but intact skin is an effective barrier that keeps bacteria from entering
and growing within the body. When there is a break in the skin, bacteria can enter the body and grow there, causing
infection and tissue reaction to injury (inflammation). The skin tissues in the infected area become red, hot, and painful.
Cellulitis is most common on the face and lower legs although skin on other areas of the body may be involved.
Risk factors for cellulitis include insect bites and stings, animal bite, or human bite; injury or trauma with a break in the skin
(skin wounds).
Lymphadenitis and lymphangitis
Alternative names:
infection - lymph glands; lymph gland infection
Definition:
An infection of the lymph glands and lymph channels.
Causes, incidence, and risk factors:
The lymphatic system is a network of vessels (channels), glands (nodes) and organs. It functions as part of the immune
system to protect against and fight infection, inflammation, and cancers. It also functions in the transport of fluids, fats,
proteins, and other substances within the body. The lymph glands, or lymph nodes, are small structures that filter the lymph
fluid. There are many white blood cells in the lymph nodes to help fight infection.
Lymphadenitis and lymphangitis are common complications of bacterial infections. Lymphadenitis involves inflammation of
the lymph glands. This may occur if the glands are overwhelmed by bacteria, virus, fungi, or other organisms and infection
develops within the glands. It may also occur as a result of circulating cancer cells or other inflammatory conditions. The
location of the affected gland(s) is usually associated with the site of the underlying infection, tumor, or inflammation. It
commonly is a result of a cellulitis or other bacteria infection (usually infection by streptococci or staphylococci).
Lymphangitis involves the lymph vessels/channels, with inflammation of the channel and resultant pain and systemic and
localized symptoms. It commonly results from an acute streptococcal or staphylococcal infection, such as from an insect or
animal bite or sting.
The infection of lymphadenitis and lymphangitis may include formation of abscesses and cellulitis. It may progress rapidly,
spread to the bloodstream within hours, and may be fatal. Lymphangitis may resemble thrombophlebitis.
Symptoms:
LYMPHADENITIS
lymph nodes may be swollen, tender, and hard
lymph nodes feel smooth or irregular to touch, or soft and "rubbery" (fluctuant) if an abscess has formed
the skin over a node may be reddened and hot
LYMPHANGITIS
- Red streaks from infected area to the armpit or groin
- may be faint, absent, or obvious
- throbbing pain along the affected area (common)
- may involve the lymph nodes (see above)
- fever of 100 to 104 degrees Fahrenheit
- chills
- loss of appetite
- headache
- general ill feeling (malaise)
- muscle aches
Erysipelas
Alternative names:
cellulitis - streptococcal; facial infection; infection - face
Definition:
An acute inflammation of the connective tissues of the skin, usually on the face, caused by infection with streptococcus
bacteria.
Causes, incidence, and risk factors:
Erysipelas is a severe form of cellulitis in which the infection is caused by streptococcus (strep) or occasionally with
staphylococcus (staph), both of which are normal skin bacteria. Erysipelas is uncommon, affecting 1 out of 10,000 people.
The skin normally has many types of bacteria on it, but intact skin is an effective barrier that keeps bacteria from entering
and growing within the body. When there is a break in the skin, bacteria can enter the body and grow there, causing
inflammation and infection.
The inflammation of erysipelas occurs most commonly on the cheeks. The infection is characterized by systemic illness,
pain, and a fever. A bright red spot appears, often near the tip of the nose. It quickly spreads to the cheeks and tends to
enlarge rapidly. It may follow a respiratory infection such as a cold, when the nose may become raw or chapped.
Abscess
Definition:
A localized collection of pus in any part of the body that is the result of the displacement or disintegration of tissue.
Causes, incidence, and risk factors:
Abscesses occur when a small area of tissue becomes infected and the body is able to "wall off" the infection and keep it
from spreading. White blood cells, the body's defense against some types of infection, migrate through the walls of the
blood vessels in the area of the infection and collect within the damaged tissue. During this process "pus" forms which is an
accumulation of fluid, living and dead white blood cells, dead (necrotic) tissue, and bacteria or other foreign invaders or
materials.
Abscesses can form in almost every part of the body and may be caused by bacteria, parasites, and foreign materials.
Abscesses in the skin are readily visible, red, raised and painful. Abscesses in other areas of the body may not be obvious
but if they involve vital organs they may cause significant damage.
Necrotizing Subcutaneous Infection
Alternative names:
Flesh-eating bacteria; fasciitis - necrotizing; infection - necrotizing subcutaneous; subcutaneous infection - bacterial;
necrotizing fasciitis
Definition:
A type of tissue infection involving skin, subcutaneous fat, the muscle sheath (fascia) and the muscle. It causes gangrenous
changes, tissue death, systemic disease, and frequently death.
Causes, incidence, and risk factors:
Necrotizing subcutaneous infection or fasciitis can be caused by a variety of bacteria including oxygen-using bacteria
(aerobic) or oxygen-avoiding bacteria (anaerobic). A very severe and usually fatal fasciitis is caused by a virulent specie of
streptococcus that is often referred to as the Flesh-eating bacteria by the press.
This type of infection develops when bacteria enter the body, usually through a minor skin injury or abrasion. The bacteria
begin to grow and release toxins that:
- directly kill tissue
- interfere with the blood flow to the tissue
- digest materials in the tissue which then allows the bacteria to spread rapidly
- cause widespread systemic effects such as shock
- Infection may begin as a small reddish painful spot or bump on the skin. This quickly changes to a painful bronzed or
purplish patch that expands rapidly. The center may become black and dead (necrotic). The skin may break open.
Visible expansion of the infection may occur in less than an hour. - Systemic symptoms may include fever, sweating, chills, nausea, dizziness, profound weakness and finally shock.
Without treatment death can occur rapidly.
Folliculitis
Alternative names:
barber's itch; pseudofolliculitis barbae; tinea barbae
Definition:
A group of superficial common infections of the hair follicle.
Causes, incidence, and risk factors:
The usual cause is the bacteria Staphylococcus (staph) or by a fungus. It may occur anywhere on the skin, as a result of
injury or damage to the hair follicle caused by friction from clothing, by blockage of the follicle, or by such things as shaving.
Barber's itch is a staph infection of the hair follicles in the bearded area of the face, usually the upper lip. Shaving
aggravates the condition. Tinea barbae is similar to barber's itch, but the infection is caused by a fungus.
Pseudofolliculitis barbae is a disorder occurring primarily in Black men where the hair of the beard grows into the adjacent
hair follicle and forms a small curled mass (aggregation of cells) within the follicle. This becomes chronically infected with any
of a variety of bacteria. It is aggravated by shaving.
Carbunculosis and furunculosis are 2 other forms of folliculitis caused by infection with staph. They may occur anywhere on
the body.
Furuncle
Alternative names:
infection - hair follicle; hair follicle infection; boils
Definition:
An infection of the hair follicles. Also see carbunculosis.
Causes, incidence, and risk factors:
A furuncle (boil) is a skin infection involving the entire hair follicle and the adjacent subcutaneous tissue. Almost everyone
experiences boils at some time. Staph bacteria are normally found on the skin surface. Damage to the hair follicle allows the
bacteria to enter deeper into the tissues of the hair follicle and the subcutaneous tissue. Furuncles may occur in the hair
follicles anywhere on the body, but they are most common on the face, neck, armpit, buttocks, and thighs.
Furuncles are generally caused by Staphylococcus aureus but may be caused by other bacteria or fungi. They may begin as a
tender red subcutaneous nodule but ultimately become fluctuant (feel like a water-filled balloon). A furuncle may drain
spontaneously, producing pus and a solid core. More often they are opened by the individual, a parent, or a physician.
Furuncles can be single or multiple. Some people have recurrent bouts with abscesses and little success at preventing them.
Furuncles can be very painful if they occur in areas like the ear canal or nose. Furuncles by the nose should be treated by a
health care provider. Furuncles that develop close together may expand and join together, a condition called carbunculosis.
Note: Itching (pruritus) of the skin may occur before the skin lesions develop.
Carbunculosis
Alternative names:
staph skin infection; skin infection - staphylococcal; infection - skin - staph; carbuncles
Definition:
A local staphylococcal skin infection involving deep subcutaneous fascia.
Causes, incidence, and risk factors:
A carbuncle consists of several furuncles (see furuncle) that develop close together. They expand and join together to form
a larger mass (aggregation of cells) with multiple drainage points. This mass may be deeper beneath the skin surface than
simple furuncles. They develop slowly, and may be so deep that they do not drain on their own. Carbuncles may develop
anywhere, but they are most common on the back and the nape of the neck. Carbuncles are less common than boils. Men
are more prone to carbuncles than women.
Staph skin infections are contagious. They may spread to other areas of the body, and may spread to other people. It is not
uncommon for several family members to be affected at the same time. Poor hygiene, run-down physical condition, friction
from clothing or shaving, and similar factors may make them more likely. Diabetics and people with suppressed immune
systems are more prone to development of staph skin infections, as are people with dermatitis, pernicious anemia, and
other disorders. Often, however, no direct cause is found for furunculosis or carbunculosis.
Erythema multiforme
Alternative names:
Stevens-Johnson syndrome; toxic epidermal necrolysis; Lyell's syndrome
Definition:
A skin disorder resulting from an allergic reaction.
Causes, incidence, and risk factors:
Erythema multiforme is a type of hypersensitivity (allergic) reaction that occurs in response to medications, infections, or
illness. Medications associated with erythema multiforme include sulfonamides, penicillins, barbiturates, and phenytoin.
Associated infections include herpes simplex and mycoplasma infections.
The exact cause is unknown. The disorder is believed to involve damage to the blood vessels of the skin with subsequent
damage to skin tissues. Approximately 90% of erythema multiforme cases are associated with herpes simplex or Mycoplasma
infections. The disorder occurs primarily in children and young adults.
Erythema multiforme may present with a classic skin lesion with or without systemic (whole body) symptoms. In Stevens-
Johnson syndrome, the systemic symptoms are severe and the lesions are extensive, involving multiple body areas
(especially the mucous membranes). Toxic epidermal necrolysis (TEN syndrome, or Lyell's syndrome) involves multiple large
blisters (bullae) that coalesce, followed by sloughing of all or most of the skin and mucous membranes.
