29. Bacterial Infections Flashcards
What is this bacterial infection? Describe it and where it is commonly located
Superficial bacterial infection: Impetigo
Small vesicles that burst–> replaced by thick honey colored crusts
Most in mouth, nose and extremeties
What is the causitive agent in this infection?
Often Staph. Aureus. Sometimes Strep. pyogenes
IMpetigo HE… What do we expect to see?
Crust in the stratum corneum have lots of neutrophils
What happens to the skin in Bullous Impetigo?
Toxins cause blistering… keritinocytes are destroyed
Awww…. whats going on with this little nugget?
Scalded Skin Syndrome
Agent responsible for this:
How does it cause this?
Staph aureus
exotoxins: Epidermolytic toxin A and Toxin B cause intraepidermal splitting through granular layer
What is destroyed froma cellular standpoing in Scalded Skin?
The desmosomes jnxs in the stratum granulosum are destroyed
Baby comes in with tender skin and macular eruption–> they quickly turn into flacid bullae. Its all over the face, neck, trunk and groin. Ddx?
Scalded skin syndrome
good prognosis in kids
may go to septicemia in adults
Describe the expected HE of scalded skin syndrome
Bullae at surface of skin… surface of epidermis and keritinocytes are destroyed.
Pt comes in with diffuse weepy inflammation on the shins. You test it and find its B-hemolytic steptococci.. Dx
Cellulitis (deep pyogenic infection)
Describe Cellulits
Diffuse inflammation of CT of skin and deeper soft tissues
B-hemolytic strep/coagulase + staph
more common on legs with expanding erythema (tender)
Pt presents with sharpy outlined edematous, erythematous and tender plaque with elevated borders. Your attending says this is often seen in the elderly, but more often on the legs. Dx?
Erysipelas
Causitive agent of Erysipelas
S. pyrogenes
Describe what organs systems/vasculature are involved in this.
Erysipelas
Bacterial skin infection involving the upper dermis and superfical cutaneous lymphatics
-sharply outlined edema, erythema, tender, painful plaque
Describe the HE of Eryipselas and how its different then Scalded skin
Both have lots of edema and neutrophils, but this is located deeper in the upper dermis while SSS is more superficial and involves the epidermis/keritinocytes
Pathology of Verrucae (image is verrucae vulgaris)
Epidermal hyperplasia
Koilocytosis (cytoplasmic vaculoization) of upper epidermal layer. See infected cells show keratohyaline granules with intracytoplasmic aggregates
What do we notice about the HE of verrucae ?
See infected cells show keratohyaline granules with intracytoplasmic aggregates
What is the dominant feature of this HE?
Koilocytosis: cytoplasmic vaculozation of the upper epidermis
YUUUCK… what is this?
Causitive agent?
Condyloma Accuminatum
HSV 6 or 11 most of the time for STD
High risk HPV
16, 18, 31, 33
(most are 6 and 11)
General charactestics of condyloma accuminatum
single or multiple paplular lesions, pearly, filiform, fungating, cauliflower or plaque like
Defining feature of condyloma accuminata?
from HPV
See the koiliocytes
HSV more common in kids, seen on lips (coldsores or gingivomatitis)
-lesions in group of clear vesicles that heal w/out scarring
HSV1
Mom brings her infant to clinic because her daughter had a diffuse rash with bumps all over and now some are blistering. You notice a mix of macules, vesicles and pustules all over.
Dx?
Varicella Zoster Vius
You just informed a dad that his daughter has chicken pox. He said he’s been giving his daughter meds to help with the pain and that none of the kids touched any of the vesicles, so he doesn’t think the other kids will get it…. set him straight on a few points
DO NOT give child Asprin (Reyes) and tell him it spreads via respiratory route so it doesn’t matter if they didn’t touch them.
Woman comes in with a rash on one side that is burning and painful.. Dx?
Herpes Zoster— shingles
Recurrace of VZV; latent rxn seen in elderly and immunocompromsed
Unilateral distribution
Explain the pathology of this virus
Acantholysis of epidermis, see multinucleated keratinocytes with intranuclear inclusions
Perineurial and intraneurial inflammation
Notice the large cells that are multinucleated keritinocytes with intranuclear inclusions… what are these and when do we see them
cowdry type A includions seen in HSV
Where does acantholysis occur in HSV
acantholysis of epiderms
What is this indicative of?
Tzank smear
use to make rapid diagnosis of HSV when taking sample from open vesicle then stain with Giemsa stain. Not as sensitive
Cutaneous infection d/t large brick shaped DNA
Molluscum contagiousum
Who gets mol.contagiousum and how and where
acquired infection from close contact of eyelids, face, axilla
Children, see in immunosuppresed pts such as HIV
SUPER contagious
Also STD–on penis, vulva, groin
Pathology of Molluscum Contagiousum
Inverted nodule… crater like
Eosinophilic cytoplasmic bodies = Hernderso-patterson bodies
Very itchy papulovesicular eruption on the hands (other sites are the fingers, penis, umbilicus, waistband and axilla)
Scabies
How is scabies contacted and when does it present
From prolounged direct human contact (not really fomites) see the eruption 4 weeks after infestation
YOu suspect dermatophytosis infection in pts nail, what test do you perform?
KOH rapid prep– see branching of septae
Common apperance of dermatophytosis
Scaly, erythematous plaques, often annular
What stain do we need to identify a dermatophyotosis (tinea) infection in the superfical stratum corneum?
PAS stain; note the fungal elements in the stratum corneum
Dx?
Tinea versicolr… superficial infeciton, seen in tropical climates caused by Malassezia globosa
See hyperpigmentation
