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E2- Bacterial Skin Infection Flashcards

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1
Q

What kind of infections raise concerns over colonization with resistant bacterial or underlying issees?

A

Recurrent infections

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2
Q

What bacteria is apart of normal skin and mucous membrane inhabitants and is often introduced through breaks in skin?

A

Staphylococci
(inoculum is usually not large, meaning proper cleansing and disinfection with germicidal soap or other agents will prevent disease in persons of normal health)

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3
Q

If a foreign body is present (splinter, stitches, surgery) what does this mean for probability of infection?

A

Infectious dose drops dramatically (takes less bacteria to cause an infection, because the bacteria can hide better)

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4
Q

What is a disease of sebaceous follicles and is a noninfectious form of folliculitis?

A

Acne Vulgaris

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5
Q

What can trigger acne vulgaris?

A

Androgen hormones

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6
Q

Is Propionibacterium acne gram positive/negative? Shape? Oxygen tolerance?

A

Gram positive anaerobic rod (normal skin flora)

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7
Q

When does inflammatory acne vulgaris develop?

A

Develops when follicular contents rupture into the dermis

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8
Q

What is primary causative agent of Folliculitis?

A

Staph. aureus (majority of abscess-type infections)

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9
Q

What causes mild pain, itching/irritation with pustules or nodules surrounding hair follicles?

A

Folliculitis

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10
Q

What should you do if 1st line treatments are not working for tx of Folliculitis?

A

Gram stain to rule or gram- negative etiology or MRSA

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11
Q

What is secondary causative agent of Folliculitis?

A

Pseudomonas aeruginosa

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12
Q

Is Staph. aureus gram positive/negative? Shape?

A

Gram positive cocci

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13
Q

Is Pseudomonas aeruginosa gram positive/negative? Shape?

A

Gram negative rod

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14
Q

Where are Pseudomonas aeruginosa infections commonly acquired? How does t appear?

A

Hot tubs

Itchy maculopapular rash, some pustules

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15
Q

What is the causative agent of most furuncles?

A

Staph. aureus

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16
Q

What is an accesses that involves a hair follicle and surrounding tissue?

A

Furuncle (boil)

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17
Q

What is a cluster of furuncles with subcutaneous connections, that extend into dermis and subcutaneous tissue?

A

Carbuncle

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18
Q

Can furuncles or carbuncles cause systemic effects like fever and prostrations (exhaustion)?

A

Carbuncle

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19
Q

What populations commonly get furuncles/carbuncles?

A

Obese, immunocompromised, diabetic and elderly

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20
Q

How are furuncles and carbuncles treated?

A

Abscesses are incised and drained
Hot compresses
Abx if > 5 mm, do not resolve with drainage, on evidence of spreading, or occur in immunocompromised or subjects at risk of endocarditis

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21
Q

What kind of abx should you use to tx furuncles or carbuncles?

A

Use antibiotics that are effective against MRSA

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22
Q

What kind of abx should you use to tx furuncles or carbuncles if pt has fever or multiple abscesses?

A

Aggressive combination therapy with rifampin

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23
Q

How can you prevent recurrent furuncles?

A

Liquid soap containing chlorhexidine/isopropyl alcohol and maintenance antibiotics.

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24
Q

What is a superficial skin infection with crusting or bullae?

A

Impetigo (Pyoderma)

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25
What causes Impetigo (Pyoderma)?
Staphylococci, streptococci or both.
26
What is severe form of impetigo featuring deep invasion of dermis caused by same agent producing non-bullous impetigo?
Ecthyma
27
What are risk factors for Impetigo and Ecthyma?
Moist environment, poor hygiene or chronic nasopharyngeal carriage of agents
28
What is the most common cause of non-bollous impetigo?
S. aureus - currently #1 cause, with MRSA in about 20% of recent cases
29
What is often co-infected with S. aureus impetigo?
Streptococcus pyogenes – (group B, β-hemolytic)
30
What are vesicles that enlarge to form bacteria-colonized fluid-filled bullae created by action of exfoliative toxin that disrupts epidermal cell connections?
Bullous Impetigo
31
What is another name for Staphylococcal Scalded Skin Syndrome?
Ritter's Disease
32
What is an acute and extensive epidermolysis due to action of staphylococcal toxin (exfoliatin) that splits the skin just beneath the granule cell layer?
Staphylococcal Scalded Skin Syndrome
33
What is unique about the bullae in Staphylococcal Scalded Skin Syndrome?
Bullae are sterile – no bacteria or leukocytes, this is due to toxin
34
Staphylococcal Scalded Skin Syndrome is positive for what sign?
Positive Nikolsky’s sign, skin peels easily, desquamated areas look scalded
35
What are acute bacterial infections of the skin and (sometimes) deeper subcutaneous tissues?
Erysipelas and cellulitis
36
What is superficial cellulitis with focal dermal lymphatic involvement? What are the causative agents?
Erysipelas | Group A Streptococcus pyogenes
37
What is another name for erysipelas?
St. Anthony's Fire
38
Patient presents with Erythematous, raised lesions with distinct borders (demarcation), rash, lymphadenopathy, fever, and chills. What do you suspect?
Erysipelas (St. Anthony's Fire)
39
What is a unilateral infection involving deeper dermis and subcutaneous tissues?
Cellulitis
40
Patient presents with areas of heat, erythema, edema, and tenderness (HEET) unilaterally on the lower leg, localized sunburn-like area with indistinct borders that blend in elevation and color to surrounding tissue. What do you suspect?
Cellulitis - Wound may not be evident
41
What are the causative agents of cellulitis?
S. aureus and S. pyogenes
42
What should you avoid in the tx of cellulitis?
NSAIDS – may mask pain of developing myonecrosis and interfere with response to agent
43
Why do cultures rarely ID the pathogen in cellulitis infection?
Too many options to test for
44
Besides the major two, what are other agents known to produce cellulitis?
``` Acinetobacter baumannii Pasteurella multocida Capnocytphaga species Aeromonas hydrophilia Vibrio vulnificus ```
45
What pathogen is associated with cat bite infections?
Pasteurella multocida
46
What pathogen is associated with cuts from an oyster or salt water injury?
Vibrio vulnificus
47
What are signs of MRSA infection?
``` Redness, swelling, warmth, pain with: Fluctuance Yellow or white center Central point (head) Draining pus or ability to aspirate pus with syringe ```
48
How is MRSA dx?
PCR assay to detect mecA gene or latex agglutination assay
49
What part of the body do necrotizing infections affect?
Subcutaneous tissue, fascia, and/or muscle
50
How does Necrotizing fasciitis present?
``` HEET Pain out of proportion* Rapid progression over several days Skin changes color (red-purple to patches of blue-gray) Thick pink/purple fluid fulled bullae Cutaneous anesthesia ```
51
What makes dx of necrotizing fasciitis difficult?
Initially overlying tissue appears unaffected | Makes diagnosis difficult without surgical intervention
52
What will determine blood supply in a necrotizing fasciitis infection?
Involvement of muscle tissue
53
What type of Necrotizing fasciitis is most common? How is it characterized?
Type 1 | Polymicrobic, one anaerobe plus one facultative anaerobe or aerobe
54
What is a major risk factor for Type 1 necrotizing fasciitis?
Diabetes
55
What is the mildest form of acne vulgaris that forms small firm pink bumps?
Papules
56
What form of acne vulgaris is clearly inflamed and contains visbable pus?
Pustule
57
What form of acne vulgaris is large, painful, inflamed, pus-filled lodged deep within the skin?
Nodule- most severe form
58
How should you treat extensive scalded skin syndrome? Does this syndrome have high or low mortality rates?
Treat as for burns | Mortality rate is low and often due to secondary infections
59
What type of Necrotizing fasciitis is "flesh-eating?"
Type 2
60
What is the causative agent of Type 2 Necrotizing fasciitis?
Group A Strep (monomicrobic)
61
How does the fascia present in Necrotizing fasciitis? Is there pus?
Fascia appears swollen and dull gray | No true pus anywhere, only thin brownish excudate
62
What differentiates Necrotizing fasciitis from Cellulitis?
Failure to respond to abx therapy | Cellulitis will typically respond in 24-48 hrs
63
What is another name for Clostridal myonecrosis?
Gas gangrene
64
What are the majority of Gas gangrene cases caused by?
Clostridium perfiringens type A
65
What type of organism is Clostridium perfiringens type A?
Spore forming, gram positive anaerobic bacillus
66
In a Gas gangrene infection, what promotes split and invasion of nearby tissue?
Production of exotoxins and insoluble H2 gas
67
Patient presents with rapid onset of pain. The skin has a bronze appearance, tense edema, is intensely tender, and crepitant. There is overlying bullae. What do you suspect?
Gas gangrene
68
How is Gas gangrene dx?
Tissue biopsy and presentation ** biopsy gram stain will show muscle necrosis, gram-variable rods, and tissue destruction
69
What is shown on a gram stain of a Gas gangrene tissue biopsy?
Muscle necrosis | Gram-variable rods and tissue destruction
70
What are the two causative agents of Toxic Shock Syndrome?
Staph aureus and Strep pyogenes
71
Patient presents with soft tissue inflammation at the site of skin infection that leads to bacteremia and necrotizing fasciitis. What do you suspect?
Streptococcal Toxic Shock Syndrome
72
What pathogen is responsible for toxic shock syndrome associated with tampon use?
Staphylococcus aureus
73
What triggers the immune response in toxic shock syndrome?
Non-specific binding of toxin to receptors
74
What treatment is usually sufficient for folliculitis?
Topical Clindamycin ointment or Benzoyl peroxide wash
75
What is the management of scalded skin syndrome?
Prompt diagnosis and therapy with penicillinase-resistant anti-staph antibiotics.
76
What is the treatment of erisepelas?
Oral or IV antibiotics targeted against the most likely agent
77
Is the treatment for cellulitis?
Empiric Abx treatment, but be aware infections may be mixed etiology
78
What is the causative agent of Type 1 necrotizing fasciitis?
Group A strep (pyogenes) and anaerobes
79
What is the treatment for necrotizing fasciitis?
- Surgical debridement - Amputation - IV antibiotics
80
What is the common way to get gas gangrene?
Direct introduction of anaerobic cells or spores into a wound
81
How is gas gangrene treated?
IV antibiotics, hyperbaric oxygen therapy, and surgical debridement/amputation *** on surgery, infected muscle wil be dark red/black, noncontactile, and will not bleed

Microbiology (23 decks)

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