Diseases of the Skin - Exam 4

What are the layers of the skin?

epidermis, dermis, subcutaneous layer

What are the points of entry?

wounds, pores, and circulation

Skin defenses: physical blockage

-keratin

-cell sloughing(cells that are dying) (desquamation)

Skin defenses: unfavorable environment for microbes

-high salt

-oils (sebum)

What are the normal flora of the skin?

-Staphylococcus epidermidis

-Corynebacterium diphtheriae

-Propionibacterium acne

-Candida sp. (fungus)

-Staphylococcus aureus

What are lesions?

changes to skin caused by infection

What do lesions include?

-rashes

-pustules

-warts

-abscesses

What are diagnostic indicators?

diseases that have specific signs

What is a macule?

a flat and discolored lesion

What is a papule?

a raised and solid lesion (bump)

What is a vesicle?

lesion filled with clear fluid

What is a pustule?

lesion filled with pus

When a fluid contains pus, how is it described?

purulent

What is an abscess?

-has decreased blood flow because theres a lot of pressure

What are important treatment considerations for abscesses?

1. antibiotics don't penetrate well

-need to travel in blood and there is decreased blood flow

2. must drain to improve blood flow

Considerations for treatment regarding the layers of the skin

the deeper in the skin the infection goes, the more serious it is

-itis

infection or inflammation of

-emia

in the blood

Oversimplified view of diagnostic lab testing

For bacterial skin specimens

1. Culture on appropriate media (observe characteristics)

-TSA, MacConkey, blood

2. Gram stain

3. Virulence factor tests

4. Identify via flowchart

The gram positive flow chart indicates what kind of bacteria?

gram positive cocci

The gram negative flow chart indicates what kind of bacteria?

gram negative rods

6 bacterial infections of the skin

1. Acne

2. Dermatitis

3. Impetigo, folliculitis, cellulitis, necrotizing fasciitis

4. MRSA

5. Toxemias caused by S. aureus

6. Cutaneous anthrax

What is the organism that causes acne?

Propionibacterium acne

-opportunistic pathogen

What is the treatment for acne?

antibiotics - topical and systemic

Epidemiology of acne

adults and adolescents

What is the organism that causes dermatitis or "hot tub rash"?

pseudomonas aeruginosa

Pseudomonas aeruginosa causing dermatitis is a _______

gram-negative rod

How is dermatitis transmitted?

contact with contaminated water/soil

Treatment of dermatitis

naturally resistant to many antibiotics, select carefully

Impetigo to Necrotizing Fasciitis

different bacterial strains will cause different diseases

Epidermis/less serious

Impetigo

Folliculitis

Cellulitis

Necrotizing fasciitis

Subcutaneous layer/more serious

What is the organism causing impetigo, folliculitis, cellulitis, and necrotizing fasciitis?

staphylococcus aureus

What are the virulence factors for impetigo, folliculitis, cellulitis, and necrotizing fasciitis caused by S. aureus?

-Coagulase

-Capsule

-Protein A

-Exfoliative toxin

-TSST-1

What is Protein A?

strong Fc-binding ability = antibody now can't do anything

Treatment for impetigo, folliculitis, cellulitis, and necrotizing fasciitis caused by S.aureus?

antibiotics

What is the organism that causes MRSA?

methicillin-resistant staphylococcus aureus

Virulence factors for MRSA

-capsule

-coagulase

-hemolysins

Treatment of MRSA

HA: vancomycin

CA: other antibiotics

Epidemiology of MRSA

HA: nursing homes, inpatient

CA: children-young adult

What are the 2 strains of MRSA?

HA-MRSA (hospital-associated)

CA-MRSA (community-associated)

Hospital-Associated MRSA

-mecA gene present

- HAVE to treat with vancomycin

Community-Associated MRSA

-mecA gene present

-resistant to methicillin but sensitive to many others

-contains PVL gene as extra virulence factor

-treat with antibiotic other than vancomycin

What is a toxemia?

toxin enters bloodstream to cause disease

-bacteria are not present at site of symptoms

-bacteria are not in the blood

Examples of toxemias caused by S. aureus

Scalded skin syndrome (SSS) and toxic shock syndrome (TSS)

What toxin causes scalded skin syndrome?

exfoliative toxin

What happens to someone who has scalded skin syndrome?

- in intestine of newborns and children

- skin peels off in sheets

What toxin causes toxic shock syndrome?

TSST-1

What happens to someone who has toxic shock syndrome?

- symptoms of skin shedding

- occurs in adults

Group A Streptococcus

causes various skin infections

What are the virulence factors for impetigo, folliculitis, cellulitis, and necrotizing fasciitis caused by GAS?

-capsule

-M protein

-SPE

-SLO

What is M protein?

virulence factor for GAS

-fuzzy layer of the capsule that inhibits phagocytosis and causes self-reactive antibodies

Treatment for impetigo, folliculitis, cellulitis, and necrotizing fasciitis caused by GAS?

antibiotics are a priority

GAS necrotizing fasciitis

"flesh eating disease" with a rapid disease course

-requires debridement

-toxemia associated with SPE A and SLO

What is one example of sequelae?

rheumatic fever

What is the organism that causes cutaneous anthrax?

bacillus anthracis

-results in large black lesions

How is cutaneous anthrax transmitted?

direct contact with endospores

Treatment for cutaneous anthrax

antibiotics

-if untreated, 20% mortality rate

8 viral infections of the skin

1. measles

2. rubella

3. roseola

4. chickenpox/shingles

5. fifth disease

6. cold sores and skin herpes

7. hand, foot, and mouth disease

8. warts

What are exanthems?

group of viral diseases characterized by a rash

-all respiratory viruses

-if there's a vaccine, it is live attenuated

Exanthems include these diseases....

1. Measles

2. Rubella

3. Roseola

4. Chickenpox

5. Fifth disease

What organism causes measles (Rubeola)? (Ruby has Koplik spots)

measles virus

How is measles transmitted?

respiratory

Culture/diagnosis of measles

-macular rash, fever, cough

-diagnostic indicator: Koplik spots

What are Koplik spots?

red patches with white centers

Epidemiology of measles

children, immunocompromised, and elderly

What is the organism that causes Rubella (german measles)? (Bella is German and pregnant)

rubella virus

How is rubella transmitted?

respiratory

Signs/symptoms of rubella

macular rash

Epidemiology of rubella

dangerous for 1st trimester pregnancies may cause miscarriage, still birth, or birth defects

What is the organism that causes Roseola? (Rosy is no big deal)

Human herpesvirus 6 (HHV 6)

How is Roseola transmitted?

respiratory

What is another name for chickenpox?

varicella

What is another name for shingles?

zoster

What organism causes chickenpox and shingles?

varicella zoster virus

-a herpesvirus

How is chickenpox transmitted?

respiratory

Epidemiology of chickenpox

more common in children

Chickenpox (Varicella) culture/diagnosis

vesicular rash

Chickenpox will always be the primary disease. However, it goes latent in nerve cells and can be reactivated as ___________

shingles

How is shingles transmitted?

can only get from yourself (stored in dormant nerve), but can transmit to others and cause chickenpox

Culture/diagnosis of shingles

vesicular rash in path of nerve

Epidemiology of shingles

most cases in older adults

Transmission of fifth disease

respiratory

Culture/diagnosis of fifth disease?

"slapped cheek" rash

Epidemiology of fifth disease

common in children but can be serious in adults and fetuses

What organism causes cutaneous herpes?

usually HSV-1

Virulence factors of cutaneous herpes

latency

-virus goes latent in nerve ganglion : hides

Cold sores (sores near mouth) is what type of herpes?

HSV-1

What organism causes hand, foot, and mouth disease (HFMD)?

Coxsackievirus16

Culture/diagnosis of HFMD

vesicular rash on hands, feet, and mouth

Epidemiology of HFMD

common in children, daycares

Hand, Foot, and Mouth Disease is a _______

enterovirus

-infects the gut

What organism most commonly causes warts?

HPV

Culture/diagnosis of warts

rough papules

Fungal diseases are called _________

mycoses

What are 2 fungal infections of the skin?

1. Ringworm (Tinea)

2. Candidiasis

What organism causes ringworm?

dermatophytes

-love moisture : caused by fungus rather than a parasite!

What organism causes Candidiasis?

candida albicans

-opportunistic infection

Epidemiology of candidiasis

prevalent after antibiotic use and in immunocompromised people

What are the 2 parasitic infections?

1. Leishmaniasis

2. Hookworm

What are 2 infections caused by insects?

1. Scabies

2. Lice

What organism causes Leishmaniasis?

Leishmania species

-protozoan parasite