Ch1 Flashcards
(78 cards)
1
Q
What are skin and soft tissue infections (SSTIs)?
A
SSTIs constitute a major infectious syndrome affecting the skin and soft tissues.
2
Q
How can SSTIs arise?
A
Through invasion of microorganisms via skin breaches or hematogenous routes.
3
Q
What are primary skin lesions?
A
Direct results of an underlying disease process, important for diagnosis.
4
Q
Name examples of primary skin lesions.
A
- Macule
- Papule
- Nodule
- Plaque
- Vesicle
- Bulla
- Pustule
- Abscess
- Purpura
- Petechiae
- Echymosis
5
Q
What are secondary skin lesions?
A
Evolve from primary lesions due to self-trauma or altered keratinization.
6
Q
Name common examples of secondary skin lesions.
A
- Scales
- Ulcers
- Eschars
- Crusted lesions
7
Q
What does the skin comprise?
A
- Epidermis
- Dermis
- Subcutaneous tissue
- Hair follicles
- Sebaceous glands
- Sweat glands
8
Q
What are the classifications of SSTIs?
A
- Infection of dermis and epidermis
- Infection of skin appendages
- Infection of fascia
- Wound infections
- SSTI due to vascular injury and neuropathy
- Lymphadenitis and lymphangitis
9
Q
What are examples of infections of the dermis and epidermis?
A
- Erysipelas
- Erythrasma
- Erysipeloid
- Impetigo
- Cellulitis
10
Q
What infections are associated with skin appendages?
A
- Infection of sebaceous gland
- Folliculitis
- Furuncle
- Carbuncle
- Hidradenitis
- Onychomycosis
11
Q
How do infections of subcutaneous tissues manifest?
A
As abscesses, ulcers, or boils.
12
Q
What can happen when infections of the epidermis and dermis extend deeper?
A
They may become subcutaneous infections, such as cellulitis.
13
Q
True or False: SSTIs can be caused by systemic diseases.
A
True
14
Q
Fill in the blank: The fascial layer is present below the _______.
A
[subcutaneous tissue]
16
Q
What is a macule?
A
Flat, nonpalpable discoloration of skin (≤ 5 mm size). If size exceeds 5 mm, it is called a patch.
17
Q
What is a papule?
A
Elevated palpable solid lesion, usually ≤ 5 mm in size.
18
Q
What is a nodule?
A
Elevated palpable solid lesion, usually > 5 mm in size. If size is > 2 cm, it is called a plaque.
19
Q
What is a vesicle?
A
Fluid-filled blister of size < 5 mm.
20
Q
What is a bulla?
A
Fluid-filled blister of size > 5 mm.
21
Q
What is a pustule?
A
Pus filled lesion of size ≤ 5 mm.
22
Q
What is an abscess?
A
Pus filled lesion of size > 5 mm.
23
Q
What are petechiae?
A
Extravasation of blood into skin, of size < 2 mm.
24
Q
What is purpura?
A
Extravasation of blood into skin, of size 2 mm - 1 cm.
25
Q
What is ecchymosis?
A
Extravasation of blood into skin, of size > 1 cm.
26
What are scales?
Flakes arising from the horny layer.
27
What is an ulcer?
A lesion with loss of epidermis and dermis.
28
What is eschar?
It is black dead tissue formed in a full-thickness wound.
29
What are crusted lesions?
Scale-like lesion, composed of dried blood and tissue fluid.
30
What are primary skin lesions?
They are the direct result of underlying disease processes and are of diagnostic importance. Examples include macule, papule, nodule, plaque, vesicle, bulla, pustule, abscess, purpura, petechiae, and ecchymosis.
31
What are secondary skin lesions?
They evolve from primary lesions by self-trauma or altered keratinization. Common examples include scales, ulcers, eschars, and crusted lesions.
32
What infections are associated with fascia?
Examples include necrotizing fasciitis, molluscum contagiosum, scabies, warts (human papillomavirus), and others.
33
What infections are associated with skin appendages?
Infections include folliculitis, furuncle, carbuncle
Infections of sebaceous glands
Inf of sweat glands
Infections of nails
34
What are common organisms implicated in SSTIs?
Common organisms include S. aureus, S. pyogenes, HSV, VZV, and various mycobacteria.
35
What are common infections of the epidermis?
Common infections of the epidermis include ringworm (tinea infection), impetigo, and erysipelas.
36
What are the infections of deep epidermis and dermis?
Infections of deep epidermis and dermis include erythrasma, erysipeloid, cellulitis, folliculitis, furuncle, and carbuncle.
37
What characterizes ringworm infections?
Ringworm infections appear as annular or ring-shaped, pruritic, scaly lesions with central clearing and raised edges.
38
What are the symptoms of impetigo?
Impetigo presents as erythematous lesions that may be non-bullous or bullous, developing into honey-colored crusts.
39
What is onychomycosis?
Onychomycosis is a fungal infection of the nail characterized by discolored, thick, fragile, or cracked nails.
40
What are the symptoms of cellulitis?
Cellulitis is characterized by painful, red, swollen lesions with a distinct border, and may include fever and regional lymphadenopathy.
41
What is hidradenitis?
Hidradenitis is a chronic infection of obstructed apocrine glands in areas like the axilla, genital, or perianal regions.
42
What are the common organisms causing skin infections?
Common organisms include S. pyogenes, S. aureus, and Corynebacterium minutissimum.
43
What is the most common etiologic agent of subcutaneous abscess?
Staphylococcus aureus is the most common etiologic agent of subcutaneous abscess.
44
What are the characteristics of a furuncle?
A furuncle begins as a red nodule and becomes painful and full of pus.
45
What is Meleney's ulcer?
A slowly progressive chronic infection of the subcutaneous tissue, usually beginning as an ulcer following trauma or surgery, potentially leading to subcutaneous necrosis.
## Footnote
Also known as progressive synergistic gangrene.
46
What types of organisms are involved in Meleney's ulcer?
Microaerophilic streptococci growing synergistically with S. aureus and other facultative or anaerobic organisms.
47
Where should specimens be taken from for better recovery of microaerophilic streptococci?
From the advancing outer edge of the lesion, not from the central portion of the wound.
48
What is anaerobic cellulitis?
An infection associated with the production of a large amount of gas by organisms present in the subcutaneous tissue, often located in extremities and common in diabetics.
49
What is necrotizing fasciitis?
A serious life-threatening condition involving infection of the fascia and often the overlying soft tissue.
50
What are the common organisms associated with necrotizing fasciitis?
* Group A streptococci
* S. aureus
* Anaerobic bacteria (especially Bacteroides and Clostridium species)
51
What is Fournier's gangrene?
A rare and often fulminant necrotizing fasciitis of the perineum and genital region due to synergistic polymicrobial infections.
52
What are surgical site infections (SSI)?
Among the most common healthcare-associated infections, occurring after nearly 3% of all surgical procedures.
53
What are common sources of infection in SSI?
* Patient's own flora (e.g., S. aureus, E. coli)
* Environmental sources (e.g., Pseudomonas, Acinetobacter)
54
What infections can arise from bite wounds?
Infections ranging from cellulitis at the site of the bite to systemic infections such as bacteremia or encephalitis (e.g., rabies).
55
What are common organisms transmitted by dog bites?
* Pasteurella
* Capnocytophaga
* Rabies
56
What complications are associated with burn wounds?
Infectious complications are major causes of morbidity and mortality in serious burn injuries.
57
How is the burn wound initially colonized?
With gram-positive bacteria (e.g., streptococci and staphylococci) from the surrounding tissue.
58
What is an eschar in the context of burn wounds?
A formed avascular covering over the burn wound due to damaged blood vessels.
59
What organisms are commonly implicated in burn wound infections by day 7?
* P. aeruginosa
* Acinetobacter
* Escherichia coli
* Klebsiella
* S. aureus
* Fungi (e.g., Candida, Aspergillus)
* Agents of mucormycosis
* Herpes simplex virus
60
What are the clinical presentations of burn wound infections?
* Burn wound impetigo
* Surgical site wound infection
* Cellulitis
* Invasive infection in unexcised burn wounds
61
What is the significance of green discoloration of a burn wound?
It points towards P. aeruginosa infection.
62
What specimens are appropriate for laboratory diagnosis of burn wound infections?
* Purulent wound exudates
* Tissue biopsy specimens
* Blood cultures
63
What is the role of the laboratory in diagnosing SSIs?
To identify the causative organism(s) and guide antimicrobial therapy.
64
What does a result of >10 CFU/g of tissue indicate?
A potentially serious infection
## Footnote
CFU stands for Colony Forming Units, a measure of viable bacterial numbers.
65
List the components of successful burn wound management.
* Early surgical excision of burned tissue
* Extensive debridement of necrotic tissue
* Grafting of skin or skin substitutes
* Topical antimicrobial agents
* Systemic antibiotics if signs of systemic involvement are present
66
True or False: Prophylactic systemic antibiotics are recommended in burn management.
False
## Footnote
Prophylactic antibiotics can lead to colonization with resistant bacteria.
67
Define a sinus tract.
A deep-seated infection that develops a channel to the skin surface for draining fluid and pus.
68
Which organisms are frequently involved in sinus tract formation associated with osteomyelitis?
* S. aureus (most common)
* Gram-negative bacilli
* Anaerobes
69
What conditions may lead to chronic draining sinuses?
* Tuberculosis
* Nontuberculous mycobacteria infection
* Nocardia infection
* Actinomycosis
* Infections associated with implanted foreign bodies
70
What are fistulas?
Abnormal channels connecting epithelial surfaces, either between two internal organs or between an organ and the skin.
71
Fill in the blank: The specimen of choice for fistula infections is _______.
biopsy
72
What are common cutaneous manifestations of systemic infections?
* Petechiae in meningococcemia
* Skin lesions from various organisms
73
Name some organisms capable of producing cutaneous lesions in systemic infections.
* S. aureus
* Meningococci
* Streptococci
* Gram-negative bacilli
* M. tuberculosis
* Fungi such as Candida and Cryptococcus
74
What is the pathogenesis of diabetic foot ulcers?
Excess blood glucose leading to impaired microvascular circulation and peripheral motor neuropathy.
75
What specimens may be subjected to culture for diabetic foot ulcers?
* Aspirated fluid or pus from the wound
* Debrided infected tissue
76
Which bacteria are most commonly isolated from diabetic foot ulcers?
* S. aureus
* Group B streptococci
* Enterobacteriaceae
* Pseudomonas aeruginosa
* Anaerobes like Bacteroides fragilis
77
What is another name for decubitus ulcers?
Bed sores or pressure sores.
78
Who is most prone to develop decubitus ulcers?
Elderly or chronically ill, bedridden patients.
79
What is the most frequent organism infecting decubitus ulcers?
Gastrointestinal flora, such as Bacteroides.
