Lecture 2: Infectious Diseases Affecting Skin, Soft, Tissue, and Eyes Flashcards
Dysbiosis
sustained alteration of microbiota resulting in overt inlammation
Functions of skin
protects uderlying tissues from microbial colonization
Each layer with specific activities
epidermal with keratinocytes (producted in stratum basal, die in stratum corneium, dry & waterproof) with dendritic langerhang cells
Dermal: sweat glands, sebceous glands
Skin microbiota
protects deeper tissues from infections
Sebaceous sites of skin have…
…the lowest bacterial diversity
Moist sites of skin colony examples
Staph and coryneobacterium (gram +)
Dry sites of skin colony examples
highest diversity, s epidermidis, and gram - species
Acne
most common skin disease in world
chronic, inflammatory condition sometimes involving cutibacterium acnes
c. acnes part of normal microbiota
Pilosebacceous unit
hair follicle + sebaceous gland
*plugged sebaceous glands can deveop into papules or nodules
sebum+ c.acnes in pores can lead to acne
Biofilms
endogenous microbiota can form biofilms
biofilm=any group of microorganisma in which cells stick together and adhere to a surface
thrive in warm, humid climates
Staphylococci
Gram + spheres form clustered arrangements
several species cause disease: S. aureus (MRSA, MSSA), S. epidermidis, S. Saprophyticus (UTIs)
makes coagulase- if it is coagulase + that is indicitive of S. aureus
produce catalase, converts h2o2 to water and o2. Catalase test is useful to distinguish staph from streptococci and enterococci
MRSA
caused by staph aureus
-resistant to all beta-lactams/cephalosporins (*EXCEPT: ceftobiprole & ceftaroline)
Staphylococcal Contact Diseases 2 types
- Localized skin infections: abcess, folliculitis, furnuncle
- toxin generated diseased: impetigo, scalded skin syndrome, toxic shock syndrome (TSS)
Abcess
Pus-filled lesion on skin normally in dermis
Folliculitis
puss-filled pocket at base of hair folliclue
caused by Grp A streptococcus
Furnuncle
infection further down hair follicle, carbuncle group of furnucles
large, warm, painful
caused by grp A streptococcus
Streptococci
gram-positive
normal skin inhabitant
grow in chains
Streptococci classification systems
Hemolytic groups: behavior on blood agar
- aplha- olive green
- beta-clear
- gamma- no change
Variants of cell wall carbs:
- Grp A= s. pyogenes
- Grp B= s. agalactiae
*important because each species treated diff
Cellulitis
pathogen
morphology
P: Grp A Streptococci
M: Non purulent (no puss associated)
severe infection of dermis and SQ tissue
skin erythema, edema, warmth
Streptococcal pharyngitis pathogen
P: Grp A Streptocci
“strep throat”
ErySipelas
Pathogen
morphology
P: Grp A Streptococci
M: superficial form of celluitis of dermis
upper dermis with clear demarcation between involved and uninvolved
Stretococcal TSS
pathology
prognosis
smyptoms
risk factor
P: Grp A Streptococci
PG: high mortality w/o treatment
S: high fever, low BP, vomiting, rash
Rx: recent sx, open wounds, super absorbent tamptons
Necrotizing fasciitis
Pathogen
P: caused by Grp. A streptococcus
M: erythema, edema, severe pain, fever, skin bullae, necrosis usually involving extremetites
Gas gangrene/ myonecrosis
Pathogen & characteristics
Morphology
Treatment
P/C: clostridium perfringens
anaerobic, gram +, spore forming rod
M: foul odor, intense pain, swelling, black skin
Tx: treat with antitoxin, and antibiotics
Cutaneous Anthrax
Pathogen & Characteristics
Treatment
Morphology
P/C: B. anthracis
aerobic, gram positive rod
Tx: treat with antibiotics
*normally for people who work with sheep
M: begins as small pruruitc papuale but formes into central vesicle or bulla
*eschar with with extensive surrounding edema is the hallmark
Wound cellulitis
Pathogen/characteristics
treatment
risk factor
P/C: psuedomonas aeruginose
aerobic, gram-negative
tx: debridement and antibiotis
rx: can happen especially after burns
Pasteurellosis
Pathogen/characteristics
risks
treatment
P: pasterurella multocida
aerobic, gram-,
Rx: dog or cat bites
tx: treat with penicillin
Cat scratch disease
Pathogen
Morphology/Symtoms
treatment
P: bartonella henselae
M/S: red-crusted blisters, headaches, malaise and low grade fever, swollen lymph nodes
tx: antibiotics for 2-4 months
Cold Sores
HSV-1, simplexvirus family of herpesviridae
after primary infection, virus becomes latent in sensory ganglia near spine, and travels back to skin along nerves to form blisters
recurrent cold sores occur when viruses are reactivates and move to the epithelium
chicken pox
Pathogen
Transmission
Morphology
Complications
P: varicella-zoster virus from varicellovirus family of herpesviridae
infection in sensory nerve ganglia
can become shingles
**not longer prevalent in US due to vaccine that became available in 1995
T: transmitted from skin to skin contact and respiratiory droplets
M: red, itchy rash turns into fluid filled blisters- which have highly infectious virus laden fluid
C: most common complication is a bacterial infection of the skin
-pneumonia, encephilits, or reyes syndrome can also occur
Shingles
caused by same virus as chicken pox
VZV remains latent in nerve cells for many years
if reactivated they can travel to the body trunk and cause blisters and patches of red
can also cause facial paralysis and severe ice tick pains
can occur repeatedly?
postherpetic neuralgia is persistence of pain for years after blisters have disappeared
human herpes virus 6
causes what diseases?
spread by…
family of beta-hyperseviridae primarily occur in infancy
causes roseola infantum; high rever, subsequent rash
spread through contact with respiratory secretions or saliva
many bone marrow transplant recipients suffer form HHV-6B viremia after transplantation
some researchers believe HHV-6A virus lies dormant for years and may be associated with multiple sclerosis later in life
EBV
Causes MONO
in BV and HHV-8 family: oncogenic viruses
sore throat, enlarged lymph nodes
more serious in immuncompormised patients, tumor formation formed from continues proliferation of infected B cells
Kaposi Sarcoma
characteristic
rx
pathogen
c: angiogenic tumor of blood vessle walls
rx: most commonly seen in immmunocompromised patiens and AIDS patients
P: caused by HHV-8, forming dark or purple skin lesions
Measles
highly contagious disease caused by member of paramyxoviridae family
transmission through respiratory droplets
Koplik spots are red pached with grain-lik centers along gum line
Rash on hairline to face, trunk, extremeties
complications inclue: bacterial disease in respiraoty tisssue, panancephalitis
Rubella (german measles)
Pathogen
transmission
symptoms
Caused by virus of Togaviridae family
transmitted through respiratoy droplets or contact
symptoms include fever, pale pink musculopapular rash
recovery prompt, relapses can occur
congenital rubells occurs when fetus is affected through placenta and children may be born with problems in eye, ear, heart
Fifth Disease
caused by member of parvoviridae
transmitted through respiratory droplets
fiery red rash on cheeks, ears, and trunks
adults can eperience symptoms similary to those of RA
HPV
common warts are benign skin growths results in a specific strain of HPS
Planta warts- on soles of feet
transmitted by contact with affected person of contaminated object
Poxviruses
small pox (variola) contagious and sometime fata
macules appear and become papules and fluid-filled vesicles
focal infection of skin, intestines, lungs, kidneys , and brain
Dermatophytosis
fungal infecition of skin, hair and nails
Sporotrichosis
fungus sporothrix schenkii forms subcutaneous lesions
Leishmania
fungus that can cause cutaneous infections
Dermatophytes
group of fungi that require keratin form growth
cause cutaneous mycoses
cause dermatophytosis as a disease
clinical presentation: classic appearance surrounded by red, scaly, elevated border
tinea capitis
dermatophyte ringworm of scalp: of skin and hair follicle
tinea coporus
dermatophytosis of skin on trunks and extremity
tinea cruris
dermatophytosis of prxomimal thigh/ buttocks
Tines Pedis
dermatophytosis of foot
Tinea unguium
infection of nail, dermatophyte
defense mechanism of eye
tears and conjuctiva
eye may contain endogenous microbiota
staphylococci, streptococci, cutibacterium
trachoma
sexually transmitted bacterial eye infection
gonorrhea
bacterial eye infection, sexually transmitted
Viral and parasite eye infections involve conjuctiva or cornea
viral pink eye
acute conjuctivitis
pharyngoconjunctival fever
acanthamoeba keratitis
ochocerciasis (river blindness)
- intermediate host is fly
- definitive host is person
