Exam 2 - Skin Pathogens

Bacillus anthracis - description

Gram +

aerobic

endospore former

(bacteria)

Bacillus anthracis - disease

cutaneous anthrax (spores enter through cuts in skin)

cutaneous anthrax - symptom

painless black eschar (necrotic) lesion

bacillus anthracis/cutaneous anthrax - signature

called “wool sorters disease”

bacillus anthracis virulence factors

polypeptide capsule

anthrax exotoxin

differences between bacillus and clostridium

bacillus: central endospores / clostridium: terminal endospores

bacillus: catalase + / clostridium: catalase -

bacillus: aerobes / clostridium: anaerobes

Clostridium perfringens - description

Gram +

anaerobic

endospore former

Clostridium perfringens - disease

gas gangrene (spores enter body through deep wound)

gas gangrene - symptom

cool black anaerobic wound

crepitus from release of gas in bacteria metabolism

Clostridium perfringens/gas gangrene - signature

alpha toxin causes cell death

Clostridium perfringens virulence factor

alpha toxin which lyses the membranes of RBCs and surrounding tissue to maintain anaerobic environment and give nutrients

Mycobacterium leprae - description

stains acid fast

Gram +

bacillus (long, clump in clusters called cords)

aerobes that prefer cooler temps

Mycobacterium leprae - disease

leprosy

leprosy - symptom

loss of pain perception (bc the bacteria typically grows in cooler tissues of nerves and skin)

Mycobacterium leprae/leprosy - signature

this long-feared disease isn’t actually very contagious

Variola virus - description

DNA virus with a complex capsid that looks like a brick

Variola virus - disease

smallpox

smallpox - symptom

eruptive blisters or pocks (can leave depressed scars when healed)

Variola virus/smallpox - signature

eradicated from nature through vaccination

Varicella-Zoster virus - description

Herpes Virus group of DNA viruses

Varicella-Zoster virus - initial disease

chickenpox

chickenpox - symptom

eruptive blisters or pocks

Varicella-Zoster virus/chickenpox - signature

goes latent in nerves after the first infection

Varicella-Zoster virus - secondary disease

shingles

shingles - symptom

painful lesions along a dermatome (the skin serviced by a single nerve)

Varicella-Zoster virus/shingles - signature

reactivation of this virus is due to lowered immunity

Measles virus - description

extremely contagious RNA virus

Measles virus - disease

measles

measles - symptom

red rash with spots in the mouth (Koplik’s spots)

Measles virus/measles - signature

extremely contagious and requires high vaccination compliance to prevent

MMR vaccine

Rubella virus - description

RNA virus

Rubella virus - disease

rubella

rubella - symptom

milder red rash

Rubella virus/rubella - signature

most dangerous to a fetus where it can cause birth defects

MMR vaccine

Human Papilloma virus - description

DNA virus that goes into latency in skin cells

Human Papilloma virus - disease

warts

warts - symptom

painless skin-colored bumps

Human Papilloma virus/warts - signature

recurrent infections can occur, genital warts increase risk of various cancers

Molloscum contagiosum virus - description

in the pox family with smallpox but MUCH milder than others in the family

Molloscum contagiosum virus - disease

molluscum contagiosum

molluscum contagiosum - symptom

small painless waxy looking bumps

Molluscum Contagiosum virus / molluscum contagiosum - signature

no latency here but it is often acquired through sexual contact

Malassezia - description

commensal skin fungus that feeds on oil

Malassezia - disease

Pityriasis versicolor

Pityriasis versicolor - symptom

mottled looking skin with patches of different shades

Malassezia/pityriasis versicolor - signature

look for “spaghetti and meatballs” under a UV black light

Dermatophytes - description

superficial fungus that digests the keratin in skin and hair

Dermatophytes - disease

“Ringworm” / tinea

ringworm - symptom

itchy raised areas between the toes or on the scalp or other places

Dermatophytes/ringworm - signature

also causes “athlete’s foot” and “jock itch”