L15: Infections of Skin and Soft Tissues! Flashcards by Katlyn Heneghan

Which of the following biochemical tests is used to differentiate between E. coli (-) and P. aeruginosa (+)?
A. Coagulase
B. Oxidase
C. Catalse

B. Oxidase

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True or False: Coagulase is a biochemical test used to differentiate between staphylococcus aureus (+) and staphylococcus (-)

True
- Converts fibrinogen to fibrin

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Which biochemical test is used to differentiate between staphylo (+) and strepto (-)?
A. Coagulase
B. Oxidase
C. Catalase

C. Catalase

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True or False: Staphylococcus is catalase (+), pseudomonas aeruginosa is oxidase (+) and staphylococcus aureus is coagulase (+)

True

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Which three bacteria make up NF?

Cutibacterium acnes
Diptheroids (aerobic, gram + bacilli)
Staphylococcus epidermis
- staphylococcus negative

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In addition two HSV (most common viral agent), bacteria and fungi can cause direct infection of skin.

Give three examples of bacterial pathogens that can cause direct skin infection:

Give one example of a fungi that can cause direct skin infection:

Bacteria
- S. aureus
- Strep pyrogenes
- Cutbacterium acnes

Fungi
- T. rubrum

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Describe cutibacterium acnes:
-Gram (+) or (-)?
-Shape
-O2 or no?

Cutibacterium Acnes
- Gram (+)
- Rod
- Anaerobic
- Diptheroids

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____ is the predominant anaerobic member of the normal skin flora that colonizes hair follicles
A. S. aureus
B. Cutibacterium acnes
C. Streptococcus pyogenes

B. Cutibacterium acnes

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How does Cutibacterium acnes degrade sebum into inflammatory substance, which attracts WBC’s
A. Produces protease
B. Produces lipase
C. Produces degradative enzyme

B. Produces lipase

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___ is the most common skin disease (primarily in teens) and is initially caused by alteration in the physiology of subaceous glands and hair follicles

Acne Vulgaris

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What are three of the ways that Acne Vulgaris can present?

1) Comedome -
(non-inflammatory lesion)
2) Inflammatory Lesion
3) Both

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How does inflammatory acne happen?

Overgrowth of NF (like C. acnes)

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What are two factors that cause the microcomedome to form?

1) Increased sebum produced
2) Follicular canal becomes plugged due to either
a - hyperproliferization of keratin
b - desquamation of cell lining the canal

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True or False: Acne is a non-infectious process when C. acnes is absent

True

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Microcomedomes may evove into non-inflammatory comedones, with the surface pore of follicular canal being either open or closed.

What is another name for an Open Comedone?

What is another name for a Closed Comedone?

Open Comedone - Black Heads

Closed Comedone - White Heads

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The plug of comedome disrupts the normal movement of ___ and ___ cells, as well as sebum.

This leads to enlarged and pressurized follicle, which eventually ruptures

hair and skin cells

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A ruptured hair follicle either heals or….

Sebum leaks out
Formation of papule/pustule (inflammatory acne)

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Inflammatory lesions (infected/colonized by C. acnes) may progress into ___ => _____ => _____

papules => pustules => nodules

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True or False: S. aureus is NF of the skin and nares that can cause skin infection by gaining entry to breaks in skin

True

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True or False: S. aureus is gram negative cocci, as well as catalase and coagulase (-).

When plated on blood agar, it is beta-hemolytic

False - while S. aureus is B-hemolytic, it is…
- Gram (+)
- Catalase/Coagulase (+)

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True or False: Bound Coagulase causes bacteria to clump together while Free Coagulase causes a protective fibrin clot to form around bacteria

True

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S. aureus can cause either: Non-Toxic Mediated Diseases (4) or Toxin Mediated Diseases (2)

List them

Non-Toxic Mediated Diseases
1. Folliculitis
2. Furuncles
3. Carbuncles
4. Epidemic Impetigo

Toxin Mediated Diseases
1. Bullous Impetigo
2. SSSS (Staphylococcal Scalded Skin Syndrome)

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True or False: Bullous Impetigo is described as a toxemia from focal infection that is usually not necessary at the skin

False - this describes SSSS

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True or False: SSSS is describe as a toxin made by pyodermic infection at the same focal infection; it is NOT toxemia!!

False - this describes Bullous Impetigo

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True or False: Folliculitis, Furuncles, Carbuncles, and Epidemic Impetigo are all contagious

True - A person exposed to a lesion will be colonized with virulent strain but will not necessarily develop disease

How do carbuncles develop? A. Folliculitis => Carbuncle B. Folliculitis => Furuncle => Carbuncle

B. Folliculitis => Furuncle => Carbuncle

____: Superficial infection of an individual hair follicle and apocrine region A. Folliculitis B. Furuncles C. Carbuncles D. Epidemic Impetigo

A. Folliculitis - Can occur on any hair bearing site on the body!

An infection of hair follicle and subcutaneous tissue suggests which Non-Toxic Mediated Disease/s? A. Folliculitis B. Furuncles C. Carbuncles D. Epidemic Impetigo

B. Furuncles C. Carbuncles Ages 3-15

____: An infection of INDIVIDUAL hair follicle that is associated with lesions that are necrotic, pyogenic abscesses. There are NO systemic signs!!! A. Folliculitis B. Furuncles C. Carbuncles D. Epidemic Impetigo

B. Furuncles

____: An infection of SEVERAL hair follicles that lead to lesions. There are systemic signs of FEVER and malaise!! A. Folliculitis B. Furuncles C. Carbuncles D. Epidemic Impetigo

C. Carbuncles

Which layer of the skin does cellulitis affect? A. Stratum corneum B. Dermis C. Epidermis D. Fat

D. Fat

Which layer of the skin does Erysipelas affect? A. Stratum corneum B. Dermis C. Epidermis D. Fat

B. Dermis

Which layer of the skin does Ecthyma affect? A. Stratum corneum B. Dermis C. Epidermis D. Fat

C. Epidermis

Which layer of the skin does Impetigo affect? A. Stratum corneum B. Dermis C. Epidermis D. Fat

A. Stratum corneum

____: Contagious superficial bacterial infection observed mostly frequently in children A. Folliculitis B. Furuncles C. Carbuncles D. Impetigo

D. Impetigo

What is the difference between Nonbullous Impetigo vs. Bullous Impetigo?

Nonbullous Impetigo - Non-toxin Bullous Impetigo - Toxin mediated

Classic Nonbullous Impetigo (Epidemic Impetigo) is caused by which two agents?

- S. aureus - S. pyogenes

_____: common infectious disease in kids (2-5 years old). Auto-inoculation causes spread. A. Nonbullous Impetigo B. Bullous Impetigo C. Epidemic Impetigo (Classic Nonbullous Impetigo)

C. Epidemic Impetigo (Classic Nonbullous Impetigo)

In what case will classic nonbullous impetigo NOT scar?

If lesion occurs in superficial epidermis

True or False: Systemic symptoms are usually present in Classic Nonbullous Impetigo and not contagious

False - systemic symptoms are NOT usually present and IS contagious!

How does Classic Nonbullous Impetigo occur? Where?

Where - superficial epidermis How - small vesicles forms => pustule forms and ruptures => thick, amber colored crest

Pathology of toxin mediated diseases of S. aureus is caused by an infection with a strain that produces sufficient quantities of ETA/ETB, also known as....

Exfoliatin Exotoxin (ETA/ETB)

What signs + symptoms are associated with ETA/ETB?

1. Epidermal Necrosis 2. Desquamination/Exfoliation of Intra-Epidermal Layers of skin produce.... A. Epidermal Necrosis B. Painful bullae => rupture => denuded skin C. Both

____: Toxin associated with ETA/ETB, which splits the intracellular bridges in the stratum granulosum of epidermis

Exfoliative Toxin

The lesions of Bullous Impetigo contain ___-producing strains of S. aureus

exfoliatin toxin (ET)

What causes the lesion in Bullous Impetigo? Do toxin and agent disseminate?

1) The toxin 2) No !

Which of the Toxin Mediated Diseases is associated with dissemination of exfoliatin exotoxin but NOT the dissemination of S. aureus? A. Bullous Impetigo B. Ritter's C. SSSS

C. SSSS

True or False: In both SSSS and Bullous Impetigo, the toxin causes the bullae.

False - SSSS: Toxin causes STERILE BULLAE Bullous Impetigo: Toxin causes LESION

True or False: SSSS is usually a SINGLE, focal infection by strains of S. aureus that produces sufficient ETA and ETB + it IS CONTAGIOUS (!!!)

True

How do you differentiate between SSSS and Bullous Impetigo?

No bacteria/growth = SSSS

_____: Most severe form of SSSS + same manifestations

Ritter's Disease of the Newborn

S. Pyogenes is GAS (group A strep), as well as: - Gram (+) or (-)? - Shape? - B-hemolytic? - Sensitive/insensitive bacitracin?

- Gram (+) - Chain forming cocci - B-hemolytic - Bacitracin sensitive

Which pathogen is sensitive to bacitracin? A. S. aureus B. Staphylococcus C. S. pyogenes D. Cutibacterium acnes

C. S. pyogenes

Which pathogen can give rise to: 1) Epidemic Impetigo / 2) Cellulitis / 3) Scarlet Fever? A. S. aureus B. Staphylococcus C. S. pyogenes D. Cutibacterium acnes

C. S. pyogenes

___ is a form of cellulitis associated with blocked lymphatics

Cellulitis

A patient is infected with S. pyogenes and develops Epidemic Impetigo. Following this, the patient begins have difficulties with urination. What complication may have arisen?

Acute Glomerulonephritis

True or False: Impetigo due to S. pyogenes infection is unrelated to pharyngeal streptococcal infections

True

Which of the following can be caused by GAS strains that are lysogenized thus these strains are capable of elaborating SPE (streptococcal pyrogenic exotoxin)? A. Epidemic Impetigo B. Cellulitis C. Scarlet Fever

C. Scarlet Fever - transduction

True or False: Streptococcal pyrogenic exotoxin (SPE's) that associated with Scarlet Fever are superantigens (Type 1) and potent immunomodulators

True

True or False: Scarlet Fever is NOT a complication of either GAS Pharyngitis or GAS Impetigo

False - Scarlet Fever *IS* a complication of either GAS Pharyngitis or GAS Impetigo

Scarlet Fever can arise as a result of which two conditions?

Impetigo and Pharyngitis

True or False: Scarlet Fever is associated with systemic signs

True - because SPE is a potent immunomodulator

____, a hyperemia, is associated with Scarlet Fever A. Enanthem B. Exanthem

A. Enanthem

What is the progression of Enanthem, as seen in Scarlet Fever?

White strawberry tongue => red strawberry tongue => red rasberry tongue Note: can occur in any mucus membrane

Scarlet Fever is associated with ____, a scarlatiniform (sandpaper-like rash) that first appears on the TRUNK then spreads PERIPHERALLY to cover whole body. A. Enanthem B. Exanthem

B. Exanthem

True or False: Enanthem is associated with Pastia's bleeding lines in folds of skin

False - this is the case with Exanthem

How does Exanthem (rash) resolve?

Desquamation!!! - of sheets of skin (palms and soles) - occurs 1-2 weeks s/p onset of illness

What are complications of Scarlet Fever/Exanthem?

1. Rheumatic Fever 2. AGN (acute glomerular nephritis)

____ is associated with honey erosions or vesicles ___ is associated with red, tender plaque ____ is associated with tender, red plaque with SHARP borders

- Impetigo - Cellulitis - Erysipelas

True or False: Cellulitis can be caused by gram (+) or gram (-) cocci

False - can be caused by gram (+) cocci or gram (-) rods

True or False: Both facultative anaerobes + obligate anaerobes—which are Gram (-) Rods—can cause Cellulitis

True

Which three Gram (+) cocci can cause cellulitis?

1. S. pyogenes (GAS) 2. S. aureus 3. S. pneumoniae

In Cellulitis, Necrotizing Skin Lesions are caused by which three atypical mycobacteria?

1. Mycobacterium ulcerans (Bruruli Ulcer) 2. Mycobacterium marinum 3. M. fortuitum

Exposure to water (freshwater or seawater) predisposes one to cellulitis with ____ as a common complication

bacteremia

Exposure to water (freshwater or seawater) predisposes one to cellulitis, which are caused by which three groups of bacteria?

1. Facultative anaerobic; Gram (-) Rods 2. Atypical Mycobacterium 3. Vibrio Vulnificus (salt water)

Anaerobic Gram (-) Rods AND Facultative, Anaerobic, Gram (-) Rods from animal bite can cause cellulitis. Which pathogens in particular (3)?

Facultative, Anaerobic, Gram (-) Rods - P. pestis and multocida - C. canimorsus

True or False: If an animal bites you and you develop cellulitis, it may be due to a gram (+) cocci or diptheroid

True

True or False: NF of mucosal surfaces, gram (-) rods, and facultative anaerobes are often caused by E. corrodens

True

Infections detected within 72 hrs after surgery is most likely due to: A. Staphylococci B. S. aureus C. B-hemolytic streptococci D. C. perfringens E. Enterococci

B. S. aureus C. B-hemolytic streptococci D. C. perfringens

Post-op infections detected 10-30 days (most common) is most apt due to: A. Gram (-) Rods B. Gram (+) Cocci - strep, staphylo, entero C. S. aureus D. Enterococci

A. Gram (-) Rods B. Gram (+) Cocci - strep, staphylo, entero

True or False: Post-op wound infections detected within 2-3 months could be caused by diptheroids/staphylococci that is Coagulase (-) Note: more prone if you have prostheses

True

___: Infections of skin (deep dermis) and may also involve SC fat

Cellulitis

True or False: Cellulitis develops within a few days and has both local inflammation and systemic signs (fever!!!!!!)

True

If there is a lesion that appears to be inflammed, may/may not be elevated, and is NOT sharply demarcated, what condition is like likely to be?

Cellulitis

True or False: Sharply demarcated edge of a lesion suggests erysipelas

True

True or False: Cellulitis may be accompanied by abscess, necrosis of overlaying skin => suppurative lesions

True

How is cellulitis treated?

Anti-microbial

Erysipelas, a specific form of cellulitis that may NOT include SC tissues and DOES include cutaneous lymphatics, is also known as...

St. Anthony's Fire

Etiologic agent that causes St. Anthony's Fire

Erysipelas

Recurrent St. Anthony's Fire suggests?

Lymphatic blockage

How do the clinical manifestations of St. Anthony's differ from regular cellulitis?

In St. Anthony's Fire... 1) Illness starts w/ systemic signs - burn, itch 2) Then: rapidly spreading erythema forms - RAISED BORDER - sharply demarcated - Indurated

What's the difference between aerotolerant/facultative anaerobe vs. obligate aerobe

Anaerobes are the predominant NF in the ___, __, and ___

mouth (gingiva); GI (colon); female genital tract

True or False: Anaerobes are commonly weak pathogen and usually a result of endogenous strains

True

True or False: Poor blood supply + Tissue necrosis can lead to Anaerobic Infections

Tru

L15: Infections of Skin and Soft Tissues! Flashcards

(96 cards)