HLTH 2501: skin infections Flashcards
what can skin infections be caused by?
bacteria, viruses, fungi, or other types of microorganisms including parasites
primary bacterial infections
are caused by resident flora
secondary bacterial infections
develop in wounds or pruritic lesions
what can deeper bacterial infections cause?
the formation of a mass of pus in the tissue which is referred to as an abscess
what does pus consist of?
living and dead WBCs and bacteria, along with tissue debris and serum
what is acne?
a staphylococcal infection
cellulitis
is an infection of the dermis and subcutaneous tissue, usually resulting secondary to an injury, a furuncle (boil) or an ulcer
what is the causative organism of cellulitis?
S aureus or streptococcus
where does cellulitis typically occur?
in the lower trunk and legs
who does cellulitis typically develop in?
those with restricted circulation or immunocompromised
signs of cellulitis
reddened area, edema, pain, and red streaks running along the lymph vessels
how is cellulitis treated?
antibiotics and analgesics for pain
furuncle
is a boil that is an infection that begins in a hair follicle and spreads into the surronding dermis
what are furuncles caused by?
S aureus
common locations for furuncles
face, neck, and back
signs of furuncles
firm, red lesion, painful nodule which develops into a abscess, and large amounts of purulent exudate
what can squeezing boils result in?
the spread of infection by autoinoculation
autoinculation
the transfer of microbes from one site of infection to another site, most likely by fingers
furuncles in the nasal area
can lead to thrombi or infection that spreads to the brain
carbuncles
are a collection of furuncles that coalesce to form a large, infected mass, which may drain through several sinuses or develop into a single large abscess
treatment for furuncles
warm compresses will promote drainage, analgesics for pain, and it can also be cut and drained
impetigo
is a bacterial infection common in children and very contagious
what causes impetigo?
S aureus but also by group A beta-hemolytic streptococci
signs of impetigo
small, red vesicle lesions on the face, yellowish-brown crusty masses formed by rupture of the vesicles, and pruritus which may spread the infection
treatment for impetigo
topical antibiotics
acute necrotizing fasciitis
‘flesh eating disease’ because the bacteria rapidly invades tissues and causes reduced blood supply to the tissues, as well as the secretion of protease enzymes that destroy tissues
what microorganism causes acute necrotizing fasciitis?
gram-positive, group A, beta-hemolytic streptococcus pyogenes (same bacteria responsible for strep throat)
what infection can toxic shock occur in?
acute necrotizing fasciitis
signs of acute necrotizing fasciitis
infected area appears inflamed and is very painful, infected area grows in size, dermal gangrene is apparent, and systemic toxicity causes fever, tachycardia, hypotension, mental confusion and disorientation, and possible organ failure
what are the signs of acute necrotizing fasciitis similar to?
cellulitis
treatment for acute necrotizing fasciitis
antimicrobial therapy, fluid replacement, excision of infected tissue, high O2 flow in hyperbaric chambers, and possibly amputation
leprosy microorganism
mycobacterium leprae
prevalence of leprosy
not as common today but still exists in Africa Asia, the South Pacific and some areas of South America
how is leprosy transmitted?
extended contact with a source
why is leprosy hard to study?
because the organism cannot easily be grown in a culture media
two types of leprosy
paucibacillary and multibacillary
paucibacillary leprosy
limited disease with fewer, less-widespread lesions
multibacillary leprosy
disease much more widespread with significant lesions and tissue damage
what does leprosy typically affect?
the skin, mucous membranes, and peripheral nerves
signs of leprosy
formation of macules (flat skin lesions with no distinct borders) and loss of feeling owing to nerve damage (can be dangerous because the individual is not aware of injuries)
diagnosis for leprosy
microscopic examination of a skin biopsy
treatment for leprosy
antibiotics (rifampicin or ofloxacin) and rehabilitation and education
bacterial infections
leprosy, cellulitis, acute necrotizing fasciitis, impetigo, and furuncles
most common cause of cold sores
herpes simplex 1
where do cold sores develop?
on or near the lips
herpes simplex
primary infection is asymptomatic as the virus remains in a latent stage in the trigeminal nerve sensory ganglion; it is then activated via an infection, sun exposure, or stress and the virus spreads
potential complications of herpes simplex
it can spread to the eyes causing keratitis or to the fingers, called herpetic whitlow
keratitis
can be a complication of herpes simplex and if infection and ulceration of the cornea
reactivation signs of herpes
a preliminary burning or tingling along the nerve and at the site of the lip and the development of a painful vesicle that will rupture and form a crust
treatment for herpes simplex
includes antiviral medication like Acyclovir, Valacyclovir, Famciclovir, and Penciclovir
another name for warts
verrucae
what are verrucae caused by?
human papillomaviruses (HPV); plantar warts are types 1-4, genital warts are 6 and 11, and cervical cancer is 16 and 18
plantar warts
commonly occur on the soles of the feet, but also on the hands and fingers
signs of verrucae
a papule, which is a solid, raised lesion with distinct margins that have rough surfaces (often white or tan); they are sometimes painful
treatment for verrucae
laser, freezing with liquid nitrogen, and topical medications that have aminosalicylic acid
how are fungal infections diagnosed?
from scrapings of the skin processed with potassium hydroxide to accentuate the spores and hyphae which becomes fluorescent in UV light
examples of viral infections
herpes simplex and warts
where are most fungal infections and why?
on the superficial skin and because the fungi live off the dead, keratinized cells of the epidermis
what may tinea cause?
dermatophytosis or ringworm
tinea capitis
is a fungal infection of the scalp that is common in school-aged children
microorganisms causing tinea capitis
microsporum canis (transmitted by dogs and cats) or trichophyton tonsurans (transmitted by humans)
signs of tinea capitis
a circular bald patch as hair is broken off above the scalp and erythema or scaling
treatment for tinea capitis
oral antifungal agents such as griseofulvin
tinea corporis
is a fungal infection on the non-hairy body parts
signs of tinea corporis
round, erythematous rings of vesicles or papules with clear centres (ringworm) and pruritus or a burning sensation
treatment for tinea corporis
topical antifungal agents such as tolnaftate or ketoconazole
tinea pedis
aka athletes foot which is a fungal infection on the feet, particularly the toes
causative microorganism for tinea pedis
trichophyton mentagrophytes or trichophyton rubrum
where is tinea pedis often found?
swimming pools and gyms
signs of tinea pedia
skin between the toes becomes inflamed and macerated, painful and pruritic fissures appear, and feet may have a foul odor
treatment for tinea pedia
topical tolnaftate
tinea unguium another name
onychomycosis
tinea unguium
is an infection of the nails, particularly the toenails; infection begins at the tipis or one or two nails, with the nail turning white then brown; the nail can then thicken and crack, and the infection spreads
what is scabies the result of?
a mite called sarcoptes scabiei
how does scabies develop?
the female mite burrows into the epidermis saying eggs in the stratum corneum; the larvae then migrate to the skin surface and then burrow into the skin in surface of nutrients; as the larvae mature, this cycle is repeated
signs of scabies
burrows appear on the skin as tiny, light brown lines, small vesicles are often apparent, erthem, and inflammation and pruritus occur
common areas for scabies
the areas between fingers, the wrist, the inner surfaces of elbows and the waistline
treatment for scabies
topical treatment with lindane
another name for lice
peciculosis
three forms of lice in humans
pediculus humanus corporis, pediculus humanus capitis, and pediculus pubis
pediculus humanus corporis
body lice
pediculus humanus capitis
head lice
pediculus pubis
pubic lice
what are lice?
small, brownish parasites that feed off human blood
how do lice develop?
female lice lay eggs on hair shafts, cementing the egg firmly to the scalp; the egg or nit appears as small and white and are attached to hairs
signs of lice
a macule or papule forms and the infected area is highly pruritic
what does itching occur in lice infections?
the saliva of the lice have excoriations that are pruritic
lice treatment
topical permethrin , malthoid, or pyrethrin or a fine-toothed comb; clothing and linen should also be washed
