Section 25- Bacterial Infections Flashcards
Most important defense against invasion of pathogenic bacteria
Intact stratum corneum
What strain of MRSA is the major cause of skin and soft tissue and more invasive infections in the community and health care settings?
MRSA USA300
Bacteria most commonly known for causing Erythrasma
Corynebacterium minutissimum
- asymptomatic except for discoloration
- patches sharply marginated
- tan or pinkish
- occuring intertriginous skin and other occluded sites
Erythrasma
Wood’s lamp fluorescence that differentiates Erythrasma from intertriginous psoriasis
Bright coral red fluorescence
Most common site for Erythrasma in temperate climates
Webspaces
Treatment for Erythrasma
Benzoyl peroxide wash
Sanitizing alcohol gel
Clindamycin lotion
Erythomycin
Bacteria that causes Pitted Keratolysis
Kytococcus sedentarius
- punched out pits in stratum corneum
- may become confluent
- more apparent with hyperhidrosis and maceration
- seen in pressure bearing areas
Pitted Keratolysis
Treatment for Pitted Keratolysis
Benzoyl peroxide wash
Sanitizing alcohol gel
Topical antibiotics- clinda, erythro
Aluminum chloride solution
Superficial colonization of hair shaft in sweaty regions
Trichomycosis
Etiology of trichomycosis
Corynebacterium tenuis
- malodorous granular concretions
- hair appears thickened, beaded and firmly adherent
Trichomycosis
Treatment for trichomycosis
Benzoyl peroxide wash
Sanitizing alcohol gel
Antiperspirant
Shaving
Cause of impetigo
S. aureus
GAS
Honey colored crusted lesions
Impetigo
Superficial blisters containing clear yellow or slightly turbid fluid with erythematous halo
Rupture easily
More common in intertriginous sites
Bullous impetigo
Ulceration with thick adherent crust
Lesions may be tender, indurated
Usually occurs at occluded sites
Common in homeless or soldiers
Ecthyma
Portal of entry of S aureus in folliculitis, furuncle and carbuncle
Ostium of hair follicle
Variant of folliculitis that is deep and extends beneath the infundibulum
Sycosis
Treatment for resistant bacterial folliculitis
Minocycline
TMP-SMX
Quinolones
Treatment for gram negative folliculitis
Discontinue antibiotics (for acne)
Benzoyl peroxide wash
Ampicillin 250mg QID
TMP SMX QID
Treatment for abscess, furuncle, carbuncle
Incision and drainage
Systemic antibiotics for immunocompromised or if there is systemic infection
Acute spreading infection of dermal and subcutaneous tissues
Red, hot and tender area of the skin
S. aureus
Cellulitis
Variant of cellulitis involving cutaneous lymphatics
Erysipelas
Usual cause of erysipelas
Beta hemolytic streptococci
Most common site of cellulitis in adults
Lower leg
Acute peripheral lesion with proximal tender or painful red linear streaks leading toward regional lymph nodes
Lymphangitis
Most common parhogen in wound infections
S aureus
Macular scarlatiniform rash
Face neck axillae groin initially
Positive Nikolsky sign
Desquamation occurs with healinf
Mucous membrane uninvolved
Staphylococcal scalded skin syndrome
- Fever, hypotension
- Generalized and blanching scarlatiniform erythroderma
- “painless sunburn”
- mucosal erythema or ulcers
- desquamation after 1 week of onset
Toxic Shock Syndrome
Cause of scarlet fever
Group A beta hemolytic strep
(S. pyogenes)
Exfoliative toxin producing S.aureus
High fever, fatigue sore throat
- face flushed with perioral pallor
- finely punctate erythema uppr part of trunk
- linear petechiae (Pastia sign)
- pharynx beefy red
- Small red macules on soft palate (Forchheimer spots)
- strawberry tongue
Scarlet fever
-palms and soles usually spared in this infection by GABHS
Scarlet fever
Drug of choice for Scarlet fever
Penicillin
Nondescript painless pruritic papule, 3-5 days after inoculation
- transmitted through contact with animals
- evolve to vesicle to ulcer to dry eschar
Cutaneous anthrax
Drug of choice for cutaneous anthrax
Systemic penicillin
Tache noir occurs in all spotted fevers except
Rocky Mountain spotted fever
All spotted fevers pattern of distribution of erythematous macules and papules except for RMSF
Centrifugal
Drug of choice for rickettsial disorders
Doxycycline 100mg BID
Triad of Rocky Mountain spotted fever
Rash
Fever
History of tick bite during 1st 3 days of illness
2-6mm pink blanchable macules that evolve to deep red papules then become hemorrhagic
Rash begins on wrists forearms and ankles then spreads to trunk thighs and face
Fever chills headache myalgia
Rocky Mountain spotted fever
Fulminant meningococcal septicemia
High fever shock widespread purpura DIC thrombocytopenia adrenal insufficiency
Waterhouse- Friderichsen Syndrome
Respiratory droplet spread
Small pink blanchable macules and papules
Petechiae and ecchymoses then
Hemorrhagic bullae that undergo necrosis and ulcerate
Meningococcemia
Maplike gray to black areas of cutaneous infarction in meningococcal infection
Purpura fulminans
Bacteria that causes cat scratch disease
Bartonella henselae
Innocuous looking small papule vesicle or pustule
With regional lymphadenopathy 2-3 weeks after inoculation
With cat contact
Cat scratch disease
Treatment for cat scratch disease
None- spontaneous resolution
Pruritic papule after insect bite
Regional lymphadenopathy
High fever
Animal reservoir rabbits squirrel beaver
Tularemia
Treatment of choice for tularemia
Streptomycin
Immunologic response to M leprae:
Acute or insidious tenderness and pain along affected nerve
Associated with loss of function
Lepra Type 1
Immunologic response to M leprae:
Erythema nodosum leprosum- seen in half of LL patients within 2 years of treatment
Most common in face and extensor limbs
Lepra Type 2
Immunologic response to M leprae:
Shallow large polygonal sloughing ulcerations on the legs
Diffuse LL individuals
Lucio reaction
What spectrum of leprosy:
Few well defined hypopigmented hypesthetic macules with raised edges covering trunk
Advanced lesions anesthetic and devoid of skin appendage
Large peripheral nerve enlargement frequent
Tuberculoid
TT, BT
What spectrum of leprosy:
Lesions are intermediary and composed of macules, papules and plaques
Anesthesia and decreased sweating
Borderline BB
What spectrum of leprosy:
Skin colored or slightly erythematous papules or nodules
Loss of hair and leonine favors
Bilateral symmetric involvement of earlobes face arms buttocks
More extensive nerve involvement
Others: upper respiratory tract, anterior chamber of eye, testes
Lepromatous
LL,BL
Key hallmarks of lepromatous leprosy
Diffuse skin infiltration
Multiple nodular lesions
Sensory loss
This stain is used for slit skin smears in leprosy
Ziehl Neelsen stain
Dermatopathology of this type of leprosy shows epitheloid cell granulomas around dermal nerves
AFB are sparse or absent
Tuberculoid
Dermatopathology of this type of leprosy shows
Extensive cellular inflitrates
Skin appendages destroyed
Macrophages filled with M leprae
Lepromatous
Treatment for tuberculoid leprosy
Dapsone plus rifampin
Treatment for lepromatous leprosy
Dapsone
Clofazimine
Rifampin
Localized infection in Lyme disease
Erythematous papule or macule expanding centrifugally with a distinct red border on bite site
May be targetoid
Most common sites: thigh axilla groin
Erythema migrans
Advanced stage of Lyme disease
Localized violaceous erythema extends centrifugally over months to years
Leaves central areas of atrophy
Acrodermatitis chronica atrophicans
Treatment for Lyme disease
Doxycycline 100mg BID for 7-14 days for early localized and disseminated disease
14-28 days for late stage
