19 Microbial Diseases of the Skin and Wounds Flashcards
Describe three reasons why the skin is not well suited for the growth of most microbes.
Multilayered, dry, salty, and acidic.
Describe the normal microbiota (microbiome/flora) of the human skin.
diphtheroid, staphylococci, and fungu
Name two reasons why Cutibacterium acnes is well suited to growing in hair follicles.
uses sebum as metabolite and produces propionic acid which decreases the pH so it can grow well.
What enzyme do most pathogenic Staphylococci produce?
coagulase
Name one species of Staphylococcus that is typically referred to as a CNS (coagulase negative Staphylococcus).
S. epidermidis
pimple
clogged pore
sty
infection of eye lash follicle
furuncle
localized pocket of pus surrounded by inflamed tissue
carbuncle
fusion of 2 or more furuncles, rounded and deeper
Describe some physical and growth characteristics of Staphylococcus.
facultative anaerobic Gram-positive coccus, grow in clusters, pairs and occasionally in short chains.
vesicles and bullae
thin walled inflammations that are close to the surface. Bullae are larger
pustules
deep pocket of pus
staphylococcal scalded skin syndrome
a. the causative agent, bacterial group
b. method of transmission
c. what causes the exfoliation associated with this disease?
a. staph aureus
b. nosocomial, person to person or fomites
c. exfoliative toxin produced by some strains which is released when the bacteria is lysogenized by a phage
What genus and species is synonymous with group A (beta-hemolytic) streptococci?
Streptococcus pyogenes
Describe the virulence factors that contribute to the pathogenicity of streptococci.
M protein- antiphagotic
capsule made of hyaluronic acid
erythogenic toxins that cause rash and fever
streptolysin S lyses neutrophils and RBC
pyoderma and erysipelas:
a. the causative agent(s), bacterial group
b. signs and symptoms
c. mechanism of transmission
a. staph aureus and sometimes strep pyrogenes
b. pustules and pus-filled vesicles that break open and crust over w/o healing
c. person to person in breaks in the skin (insect bites or cold sores)
necrotizing fasciitis:
a. causative agent, bacterial group
b. alternate name
c. signs and symptoms
a. strep pyrogenes
b. flesh eating bacteria
c. intense pain and blackening of tissues, open wounds
cellulitis:
a. causative agent, bacterial group
b. mechanism of transmission
c. signs and symptoms
a. staph aureus and strep pyrogenes
b. not transmitted, deep tissue infection
c. red inflamed skin on lower limbs
cat scratch disease:
a. causative agent
b. transmission
c. signs and symptoms
a. Bartonella henselae
b. bite, lick, or scratch from infected cat
c. pustule at site of entry, swollen lymph nodes, headache and fever
Describe some infections caused by Pseudomonas and key characteristics.
otitis externa and opportunistic infections
green discharge
Rocky Mountain Spotted Fever (RMSF):
a. the causative agent and bacterial group
b. method of transmission (common name for the vector)
c. signs and symptoms
a. rickettsia ricketsii
b. tick bite
c. headache, joint/muscle pain, fever, rash begins on hands and feet
anthrax:
a. causative agent
b. various forms of the disease
a. bacillus anthracis
b. inhalation, cutaneous, and intestinal
gas gangrene:
a. the causative agent, bacterial group
b. treatment
a. Clostridium perfringens
b. debridement, amputation, hyperbaric chamber
Compare and contrast HHV-1 (HSV-1) and HHV-2 (HSV-2).
HHV1: cold sores, transmission by saliva or direct contact, usually above waist, latent in trigeminal ganglion
HHV2: genital, sometimes oral, sexually transmitted, below the waist, latent in sacral ganglion
warts:
a. causative agent
b. transmission and pathogenesis
c. treatments
a. HPV
b. transmitted through fomites, direct contact, or autoinoculation. Multiples in skin cells and sheds in dead skin cells.
smallpox:
a. transmission
b. signs and symptoms
a. droplet or direct contact
b. fever, headache, and skin lesions that leave severe scars
chicken pox:
a. transmission
b. conditions that increase the risk of Reye’s syndrome
a. direct contact, inhalation of aerosols from vesicular fluid of skin lesions of acute varicella or zoster, and possibly through infected respiratory secretions that also may be aerosolized.
b. aspirin ingestion increases risk
Explain how varicella-herpes zoster causes shingles.
virus lays dormant in dorsal root ganglia and travels along peripheral nerve to face or torso resulting in severe pain
List some other “childhood” rashes caused by viruses that we immunize against.
measles and rubella
Distinguish between the various tineas (cutaneous mycoses) caused by dermatophytes.
tinea pedis (athlete’s foot)
tinea corporis (whole body)
tinea capitis (ring worm)
tinea cruris (jock itch)
tinea unguium (nail bed)
leishmaniasis:
a. causative agent
b. transmission
c. signs and symptoms of the various forms of the disease
a. leishmania genus
b. sandfly bite
c. visceral disease: reoccurring fever, enlarged spleen and liver, weight loss
cutaneous disease: disfiguring sores
scabies:
a. causative agent
b. transmission
c. signs and symptoms
d. a common secondary infection
a. sarcoptes scabiei mite
b. shared fomites or sexual contact
c. raised pimple like rash that blisters
d. impetigo
