Skin And Soft Tissue Infections

Front 1

What are the Group I simplified classification system features?

Back 1

1.) superficial, localized infections
2.) superficial, diffuse involvement
3.) multiple, discrete, superficial lesions
4.) microbial etiologies and host predispositions vary
5.) most forms usually respond to antimicrobial therapy alone

Front 2

What are the group 2 classification features?

Back 2

1.) necrosis of subq tissues +/- fascia
2.) necrosis of subq tissue, fascia, and muscle
3.) microbial etiologies and host predispositions vary
4.) require surgical and medical therapy

Front 3

Group 1 Infections: A. Impetigo: features (5)

Back 3

1.) common disease in young children, warm climates
2.) superficial infection in epidermidis, exposed areas
3.) causes vesiculo-pustular lesion; "honey-colored" crust
4.) caused by S. aureus or Group A Streptococci +/- S. aureus
5.) non-suppurative complications:
a.) acute post-streptococcal glomerulonephritis
and
b.) associated with nephritogenic strains

Front 4

Group 1 Infections: B. Bullous impetigo:

Back 4

1.) large, tense fluid-filled bullae
2.) caused by exfoliative toxin-producing S. aureus

Front 5

Group 1 Infections: C. Folliculitis (4 features):

Back 5

1.) infection within hair follicles
2.) small (2-5 mm) papular pruritic lesions
3.) S. aureus is a common cause
4.) pseudomonas aeruginosa related to hot tub and whirl pools

Front 6

Group 1 Infections: D. furuncles and carbuncles: (3 features)

Back 6

1.) s. aureus invades base of hair follicle or sebaceous gland
2.) Localized small abscess in subq tissue (furuncle)
3.) infection may spread ot several hair follicles with formation of a large subQ abscess (carbuncle)

Front 7

Group 1 Infections: E. acute lymphadenitis (5 features)

Back 7

1.) acute suppurative infection of lymph nodes
2.) may involve submaxillary, cervical, axillary, or inguinal lymph nodes
3.) S. aureus and group A strep are common causes
4.) cat-scratch disease, tularemia, lyme disease, plague, LGV, nocardia
5.) M. tuberculosis and M. scrofulaceum

Front 8

Group 1 Infections: F. SSSS (4 features)

Back 8

1.) synonym: Ritters' disease
2.) usually occurs in children: mild systemic component
3.) phage group II S. aureus with exfoliative toxin
4.) widespread, confluent erythematous rash with subsequent peeling (desquamation) of skin that mimics a 2nd degree burn

Front 9

Group 1 Infections: G. Toxic shock syndrome: (5 features)

Back 9

1.) caused by S. aureus strains producing TSST-1 (Toxic shock syndrome toxin-1) or streptococci;
2.) causes fever and shock, sunburn-like rash with desquamation, especially palms and soles
3.) GI, renal, muscular, hematologic, hepatic, mucous membrane and CNS involvement in varying combos; must meet case definition criteria
4.) post surgical, traumatic, foreign body associated, tampon users
5.) patients require aggressive fluid replacement and supportive care

Front 10

Group 1 Infections: H.) Erysipelas: (5 features)

Back 10

1.) involves dermis and epidermis
2.) skin is hot, red, edematous
3.) systemic toxicity is common
4.) affected area has well-defined elevated margins ("shelf" or "step off" on exam)
5.) S. pyogenes is most common and less often is S. aureus

Front 11

Group 1 Infections: I.) Cellulitis: (4 features):

Back 11

1.) epidermis and subcutaneous tissue is involved but may extend to deeper tissues and difficult bedside distinction with some infections; requires serial clinical assessments
2.) erythema, edema, and warmth of affected area
3.) margins are poorly defined; not elevated
4.) most common causes in adults are S. aureus and Beta-hemolytic streptococci (Group A, B, C, F, G)

Front 12

Group 1 Infections: J.) invasive group A streptococcal disease

Back 12

1.) reported with increasing frequency
2.) risk factors: trauma, varicella, wounds, IDU
3.) clinically, pain out-of-proportion to findings, +/- dusky erythema, bullae
4.) may initially be limited to superficial tissues extend to deeper tissues
5.) life and/or limb threatening

Front 13

Group 1 Infections: K.) Bite-related cellulitis (4 diff features)

Back 13

1.) likelihood of infection: human bites > cats > dogs
2.) bacterial etiology based on extant mouth flora: streptococci, S. aureus, anaerobes Eikenella (humans), P. multocida (cats), capnocytophaga (dogs)
3.) often develops less than 24 hours after bite, especially when due to P. multocida
4.) focal complications occur in 30% of patients (e.g. tenosynovitis, septic arthritis, osteomyelitis, enocarditis, etc).

Front 14

Group 1 Infections: L.) Recurrent cellulitis with lymphedema;

Back 14

-1.) occurs months to years after surgery (CABG, mastectomy, etc).
2.) often involves extremity due to altered lymphatic drainage (e.g. saphenous venous harvest site)
3.) beta-hemolytic streptococci often involved
4.) recurrences are common if tinea pedis or other portal of entry/breach present

Front 15

Group 1 Infections: M.) Skin/soft tissue lesions as a result of systemic infection (i.e. metastatic infection)

Back 15

1.) endogenous source
2.) infective endocarditis, ecthyma gangrenosum, meningococcemia, RMSF, candidemia, DGI, smallpox, etc.
3.) treat the underlying systemic infection

Front 16

Group 2 infections: A.) synergistic necrotizing cellulitis / gangrene: (6 features)

Back 16

1.) risk factors: diabetes mellitus, alcoholism, advanced age, malignancy, peripheral vascular disease, trauma (may be quite minor)
2.) extremities, perineal area, decubiti, infections spread rapidly along natural tissue planes
3.) clinical clues: edema (beyond extent of erythema); skin changes, tissue air on plain films, skin anesthesia, ecchymosis/ necrosis/ systemic progression
4.) high index of suspicion necessary as may appear as cellulitis early in course
5.) streptococci, enteric rods, bacteroides, S> aureus, pllymicrobial
6.) tissue gram stain, cultures, blood cultures

Front 17

Group 2 Infections: B.) necrotizing fascitis (5 features)

Back 17

1.) involves epidermidis, dermis, subq and superficial fascia +/- deep fascia and muscle
2.) portal of entry: = site of trauma (may be minor)
3.) group A streptococci: difficult Dx early in course; severe pain (out of proportion to findings) +/- fever, +/- GI symptoms are hallmark; leas to overwhelming systemic infection
4.) skin color changes from red-purple to patches of blue/gray hemorrhagic bullae, crepitus, soft tissue air on xray, burn-like appearance, hypesthesia, gangrene, +/- compartment syndrome
5.) MRI to delineate extent

Front 18

Group 2 Infections: C.) diffuse myositis, including clostridial myonecrosis (Gas gangrene): 5 features

Back 18

1.) most cases assoc. with deep, penetrating trauma, crush injuries, injecting drug use; spontaneous or recurrent cases may occur (e.g. assoc with GI lesions esp. due to clostridium septicum)
2.) presents with septic picture shock and multi-organ system failure
3.) involves skin, subcutaneous fascia, and muscle tissue
4.) pain, bronze discoloration of skin, watery discharge, hemorrhagic bullae, gas in tissues, gangrene
5.) mixed aerobic/ anaerobic organisms, streptococci, C. perfringens, other clostridial sp.

Front 19

Group 2 Infections: D.) focal pyomyositis (4 features)

Back 19

1.) acute focal infection of skeletal muscle; HIV-infected individuals
2.) causes fever and induration of affected muscle
3.) MRI
4.) usually s. aureus; blood cultures seldom positive

Front 20

Group 2 Infections: E.) vibrio infections: V. vulnificus V. parshemolyticus (5 features)

Back 20

1.) preceding exposures to salt water or shellfish, eg, US Gulf Coast and Chesapeake Bay
2.) severe cellulitis, edema, intense pain
3.) hemorrhagic bullae may ocur in area of cellulitis
4.) secondary bacteremia and metastaic bullae are common
5.) underlying liver disease; immune suppression

Front 21

Group 2 Infections: F.) Aeromonas myonecrosis:

Back 21

1.) follows injury sustained in fresh water or by fish, medicinal leeches, etc.
2.) marked by edema, bullae, gas in tissues, bacteremia

Front 22

6 types of therapy for Group I infections:

Back 22

a.) oral antimicrobials (targeted against gram positive organisms) i.e. pyogenic streptococci, S. auresu in mildly ill outpatietns
b.) topical antimicrobials (neosporin, mupirocin in impetigo or antifungals to treat tinea pedis portal of entry)
c.) targeted therapy if pathogen is identified (e.g. pseudomonas in whirlpool-associated folliculitis)
d.) some grou pI infections require drainage: carbuncle, bite-related infeciton, superficial abscess
e.) toxin-mediated disease requires supportive care as well (e.g. TSS)
f.) moderately or severely-ill patients with infections should be admitted and treated with parenteral antimicrobials initially

Front 23

4 types of therapy for Group II infections:

Back 23

a.) typically require some form of surgical treatment as well as systemic antimicrobials
b.) surgery is primary and generally involves debridement (often multiple and extensive)
c.) combination antimicrobial therapy to cover potential pathogens
d.) clindamycin useful in clostridial and group A streptococcal necrotizing infections due to protein synthesis inhibitory effects that interfere with toxin synthesis