SSTIs Flashcards
(130 cards)
1
Q
Purulent SSTIs
A
- Impetigo
- Cutaneous abcesses
- Inflamed epidermoid cysts
- Furuncles
- Carbuncles
2
Q
What is Impetigo?
A
- Highly contagious infection of epidermis
- Typically transmitted through direct contact
- Occurs most commonly in children
- Most frequently affects face and extremities
3
Q
What are the two types of Impetigo?
A
Nonbullous (~70% of cases)
Bullous
4
Q
What are the predisposing factors of Impetigo?
A
- Group A Strep skin colonization or S. aureus nasal colonization.
- Hot, humid summer weather
- Areas with poor hygiene and in crowded living conditions
- Minor trauma (insect bite, abrasion)
5
Q
What is Nonbullous Impetigo?
A
- Caused by: Strep pyogenes (Group A) or Staph aureus
- Small, fluid filled vesicles → pustules → pustules rupture → golden yellow crusts over an erythematous base
6
Q
What is Bullous Impetigo?
A
- Caused by: Staphylococcus aureus
- Vesicles → bullae with clear, yellow fluid → bullae rupture, forming thin, light brown crusts
- Usually affects neonates and children < 5 yo
7
Q
Ecthyma
A
- Ulcerative form of impetigo causing painful fluid- or pus-filled sores; heals with scarring
- Requires abx tx
8
Q
Topical Treatment of Impetigo
A
- Topical therapy is as effective as systemic therapy
- Mupirocin or retapamulin applied to lesions
9
Q
Duration of Topical Treatment of Impetigo
A
5 days
10
Q
Systemic Treatment of Impetigo (suspicion or confirmation of MRSA)
A
- Clindamycin
- Doxycycline
- TMP/SMX
11
Q
Systemic Treatment of Impetigo (no suspicion of MRSA)
A
- Dicloxacillin
- Cephalexin
12
Q
Duration of Systemic Treatment of Impetigo
A
7 days
13
Q
What is Folliculitis?
A
- Pyoderma located within hair follicles
- Small (<5mm), erythematous (sometimes pruritic) papules usually covered by central pustule
- Develops in areas of friction and perspiration (armpits, groin, etc.)
14
Q
What are the causative organisms of Folliculitis?
A
- S. aureus (most common)
- P. aeruginosa (swimming pools, hot tubs, whirlpools)
- Candida spp (prolonged antibiotics or corticosteroids)
15
Q
What is the treatment for Folliculitis?
A
- Saline compresses (promotes drainage)
- Topical therapy with antibacterials or antifungals sufficient
16
Q
What are Furuncles (Boils)?
A
- Deep inflammatory nodule that typically develops from preceding folliculitis.
- Lesions often rupture and drain spontaneously
17
Q
What is the treatment for Furuncles?
A
Application of moist heat to promote drainage
18
Q
What are Carbuncles?
A
- When infection extends to involve several adjacent follicles producing a coalescing inflammatory mass with pus draining from multiple follicular orifices.
- Progression from furuncles
- Typically found at nape of neck, face, armpits, buttocks
- Fever and malaise usually present
19
Q
What is the causative organism of Furuncles and Carbuncles?
A
S. aureus
20
Q
What are the predisposing factors for Furuncles and Carbuncles?
A
- Diabetes, obesity
- Inadequate personal hygiene
- Close contact with others with furuncles
- Anterior nares colonization with S. aureus (recurrent cases)
21
Q
What is the treatment for Furuncles and Carbuncles?
A
- Incision and drainage (I&D)
- Systemic antibiotics rarely required unless fever or multiple furuncles/carbuncles
22
Q
Causative Organism of Cutaneous Abcesses and Inflamed Epidermoid Cysts
A
S. aureus
23
Q
Treatment of Cutaneous Abcesses and Inflamed Epidermoid Cysts
A
- Incision and evacuation of pus and debris
- Systemic antibiotics usually NOT recommended
24
Q
When to use systemic abx for purulent SSTI
A
- Systemic signs of infection (fever, etc.)
- Multiple abcesses
- Lack of response to I & D
- Immunocompromised
25
Duration of Systemic Abx Therapy for Purulent SSTI
5 days
26
When is MRSA coverage warranted for purulent SSTI?
- Long-term care facility
- IV drug abuse
- HIV
- MSM
- Incarceration
- Military
- Native American
- Sharing razors or sports equipment
- History of MRSA infection/colonization
- Current MRSA infection elsewhere
- Failed initial abx therapy
- Penetrating trauma
- Markedly impaired host defenses
- Severe infection with systemic sxs and/or hypotension
27
Duration of Therapy for Purulent SSTI if concern for MRSA
5-7 days
28
PO Antibiotics for MSSA Purulent SSTI
- Dicloxacillin
- Cephalexin
29
IV Antibiotics for MSSA Purulent SSTI
- Nafcillin/Oxacillin
- Cefazolin
- Clindamycin (if pt has beta-lactam allergy)
30
PO Antibiotic Therapy for MRSA Purulent SSTI
- Doxycycline
- TMP/SMX
- Clindamycin (need to do D-test first to check susceptibility)
31
IV Antibiotics for MRSA Purulent SSTI
- Vancomycin (**DOC**)
- Linezolid
- Ceftaroline
- Daptomycin
- Oritavancin (**preferred for outpatient**)
- Dalbavancin (**preferred for outpatient**)
- Tedizolid
32
Treatment of Recurrent S. aureus SSTI
- Nasal decolonization: Mupirocin 2% intranasal x 5-10 days
- Topical decolonization: Chlorhexidine or bleach bath
33
What is Cellulitis?
- Acute, spreading infection of skin that involves epidermis and dermis.
- Local tenderness/pain, swelling, warmth, erythema
34
What is the location of Cellulitis?
Commonly on lower legs
35
What are the systemic manifestations of Cellulitis?
Fever, tachycardia, confusion, hypotension, leukocytosis
36
Erysipelas
Superficial form of cellulitis with clearly defined borders of inflammation
37
What are the predisposing factors for Cellulitis?
- Previous trauma (laceration, puncture wound)
- Conditions that cause skin to be more fragile or local host defenses less effective (obesity, diabetes, previous cutaneous damage, edema (from venous insufficiency or lymphatic obstruction), surgical procedures, eczema)
38
Common Pathogens Causing Cellulitis
- S. pyogenes (Group A) - **most common**
- S. aureus
39
How to Differentiate Between Cellulitis Caused by S. pyogenes or S. aurues
S. aureus infection usually has pus, purulence, or abcess
S. pyogenes infection does not
40
Diagnosis of Cellulitis
- Done by physical exam
- Routine diagnostic testing NOT recommended
41
Symptoms of Mild Cellulitis
- No purulence
- No systemic sxs, AMS, or hemodynamic instability
42
Treatment of Mild Cellulitis
- Outpatient tx
- Penicillin
- Augmentin
- Cephalexin
- Clindmycin (if beta-lactam allergy)
43
Signs/Symptoms of Mederate-Severe Cellulitis
- Deeper infection
- Poor adherence
- Systemic sxs
- Failed outpatient therapy
- Immunocompromised
44
Treatment of Moderate-Severe Cellulitis
- Inpatient tx
- Penicillin IV
- Cefazolin or ceftriaxone
- Clindamycin (if beta-lactam allergy)
45
Duration of Cellulitis Treatment (regardless of severity)
5 days
46
When is MRSA coverage indicated for cellulitis?
- Penetrating trauma
- Evidence of MRSA infection elsewhere
- Nasal colonization with MRSA
- Injection drug use
- Purulent drainage
- Severe infection (necrotizing)
47
PO Treatment for MRSA Cellulitis
- TMP/SMX
- Doxycycline
- Clindamycin
48
IV treatment for MRSA Cellulitis
- Vancomycin (**DOC**)
- Linezolid
- Daptomycin
- Ceftaroline
- Tigecycline
- Telavancin
- Tedizolid
- Oritavancin
- Dalbavancin
49
Cellulitis Treatment if Coverage for Strep and MRSA Needed
- Clindamycin
- TMP/SMX + Beta-Lactam
- Doxycycline + Beta-Lactam
50
Non-Medication therapy for Cellulitis
Elevation of affected area
51
Adjunctive Treatment for Cellulitis
Systemic corticosteroids x 7 days in non-diabetic adults
52
Recurrent Cellulitis
- 2+ discrete SSTIs over a 6 month period
- 3-4 SSTIs/year
53
Prophylactic antibiotics for Recurrent Cellulitis
- Penicillin V
- Erythromycin
- Benzathine penicillin
54
Duration of Cellulitis Prophylaxis
Continue therapy for as long as predisposing factors are present
55
What is some general information about Bite Wounds?
- Most bites are due to dogs or cats
- Cat bite wounds are usually more severe and have higher proportion of osteomyelitis and septic arthritis
- Human bite wounds are typically more serious than animal bites
- Predominant pathogens: oral flora, skin flora
56
What are the complications caused by bite wounds?
Septic arthritis, osteomyelitis, subcutaneous abscess formation, tendonitis, bacteremia (rarely)
57
What is the bacteriology of Dog/Cat bite wounds?
- Pasteurella - most common
- Capnocytophaga canimorsus: causes bacteremia and fatal sepsis especially in asplenia or underlying hepatic disease patients
58
What is the bacteriology of Human bite wounds?
- Strep (esp. viridans)
- Staph
- Eikenella corrodens - most common
- Anaerobes present in \> 60% of cases
59
What are some vaccines that can be used for Bite Wounds?
Tetanus. Rabies (for all feral, wild animal bites, areas with high prevalence of rabies)
60
Drug of Choice for Treatment of Bite Wounds
Beta-lactam + Beta-lactamase inhibitor
- Augmentin
- Ampicillin/sulbactam
- Piperacillin/tazobactam
61
When should IV therapy be used for bite wounds?
- Failed initial oral abx
- Bite involves hand, head, joint
- Presence of lymphatic spread
62
Bite Wound Treatment (**beta-lactam allergy**)
2nd or 3rd generation cephalosporin, TMP/SMX, levofloxacin, ciprofloxacin
PLUS
Metronidazole
OR
Single-Agent Options: carbapenem, moxifloxacin, doxycycline
63
Duration of Treatment for Bite Wounds
5 days
64
What should be avoided in the treatment of Bite Wounds?
1st generation CEPHs and Penicillinase-Resistant PCNs (oxacillin, nafcillin, dicloxacillin), Macrolides, Clindamycin
65
Wound closure for Bite Wounds
Wound closure is NOT recommended unless affected area involves face
66
What are Necrotizing Skin and Soft Tissue Infections?
- Aggressive subcutaneous infection of the fascial and/or muscle compartments
- Can cause major tissue destruction and death
- Usually develops from an initial skin break from trauma or surgery
- **Life threatening emergency** - requires surgery and broad spectrum abx
67
What are the clinical features of Necrotizing Fasciitis
- Severe pain disproportional to clinical findings
- Hard, wooden feel of subcutaneous tissue
- Crepitus (including gas in tissue)
68
Type II (Monomicrobial) Necrotizing Fasciitis
- Commonly affects lower extremities
- Common cause: **S. pyogenes**
69
Type I (Polymicrobial) Necrotizing Fasciitis
- Common in IV drug users (at injection site)
- Originates from **bowel** or **genitourinary** flora
- **Polymicrobial**: average of 5 pathogens per wound
70
Diagnosis of Necrotizing Fasciitis
- Definitive diagnosis via **surgical exploration**
- Culture and gram stain of deep tissue sample from surgery
71
Treatment of Necrotizing Fasciitis
Emergent surgery intervention followed by debridement every 24-36 hours
72
Empiric Therapy for Nectrotizing Fasciitis
- Broad spectrum (including MRSA and anaerobes)
- Vanco PLUS piperacillin/tazobactam (or carbapenem)
73
Directed Therapy for Necrotizing Fasciitis (**Strep**)
PCN + clindamycin
74
Directed Therapy for Necrotizing Fasciitis (**Staph**)
- MSSA: 1st generation cephalosporin or oxacillin
- MRSA: Vanco
75
Duration of Treatment for Necrotizing Fasciitis
Until debridement is no longer necessary
76
Clinical Features of Infectious Gangrene
- Gas production leading to crepitus
- Muscle necrosis
- Progression within hours
77
What is Trauma-Associated Clostridial Gas Gangrene?
- **C. perfringens** most frequent cause
- Skin initially pale --\> bronze --\> purplish red.
- Signs of systemic toxicity: tachycardia, fever, diaphoresis --\> shock and multiple organ failure
78
What is Spontaneous Clostridial Gas Gangrene?
- **C. septicum** most frequent cause
- Neutropenic and GI malignancy patients
79
Diagnosis of Infectious Gangrene
Diagnosis by **surgical exploration** during emergent debridement
80
Treatment of Infectious Gangrene
Emergent surgical debridement + appropriate abx
81
Empiric Antibiotic Therapy for Infectious Gangrene
- Broad spectrum (including MRSA and anaerobes)
- Vanco PLUS piperacillin/tazobactam
82
Directed Antibiotic Therapy for Infectious Gangrene (**Clostridial**)
PCN + Clindamycin
83
What are the general characteristics of Diabetic Foot Infections?
Usually arise from a **skin ulceration** that occurs as a consequence of peripheral neuropathy or wound from trauma
84
Risk Factors for Diabetic Foot Infections
- Peripheral neuropathy
- Peripheral vascular disease
- Poor glycemic control
- Foot deformities
- Ulcer present \> 30 days
- History of recurrent foot infections
- Previous lower extremity amputation
- Walking barefoot
85
Diagnosis for Diabetic Foot Infections
Purulent secretions OR
**2 classic signs or symptoms of inflammation**: erythema, warmth, tenderness, pain, or induration
**Definitive Diagnosis**: culture and sensitivity
**MRI** to rule out abscess or osteomyelitis
**Labs** - WBC, ESR, CRP, Procal
86
What organisms cause the acute/superficial (typically monomicrobial) diabetic foot infections?
- S. aureus
- S. epidermidis
- Beta-hemolytic strep (Group A, B, C, G)
87
What organisms cause chronic/deep (typically polymicrobial) diabetic foot infections?
- S. aureus
- Strep
- Enterococcus
- Enterobacteriaceae
- Pseudomonas
- Anaerobes
88
What organisms cause necrosis, gangrene, or malodorous drainage in diabetic foot infections?
- Anaerobic Strep
- Bacteroides
- Clostridium
89
Mild Diabetic Foot Infection
- Local infection
- Erythema **0.5-2 cm**
90
Moderate Diabetic Foot Infection
- Local infection
- Erythema **\> 2 cm**
- Deeper infections
91
Severe Diabetic Foot Infection
Local infection with **systemic** signs of infection
92
Diabetic Foot Infections Requiring Hospitalization
- Severe infection
- Moderate infection with complicating features (severe PAD, poor social support)
- Poor compliance with or failing outpatient therapy
93
Treatment of Diabetic Foot Infections
Debridement, proper wound care, + appropriate abx
94
Uninfected diabetic foot ulcers
**Avoid** antibiotic use
95
Mild-moderate diabetic foot infections
- Narrow spectrum agent: aerobic GPC coverage
- High bioavailability PO agents may be sufficient (Augmentin)
96
Severe or chronic diabetic food infections
- Broad spectrum agents: GPC (+MRSA), GNR, anaerobes
- Vanco PLUS Zosyn, Carbapenem, Cefepime, Ceftazidime, or Aztreonam
- Parenteral therapy (may switch to PO when stable)
97
Duration of treatment be for mild diabetic foot infections
1-2 weeks
98
Treatment duration for moderate-severe diabetic foot infections
2-3 weeks
99
Wound care for diabetic foot infections
- Dressed in a manner that allows daily inspection and encourages a moist wound-healing environment.
- Removal of pressure from foot wound is necessary for healing.
- Accuzyme: topical debriding agent
100
Need for surgery with diabetic foot infections
-I/D of necrotic tissue
Revascularization of lower extremity
-Urgent amputation for extensive necrosis or life-threatening infection
101
What is Osteomyelitis?
- Progressive infectious process that can involve one or multiple components of bone
- Characterized by inflammatory destruction of bone, necrosis, and new bone formation
102
Signs and Symptoms of Osteomyelitis
- Dull pain at involved site
- Local inflammation (tenderness, warmth, erythema, swelling)
- Systemic symptoms may be present
103
Cierny and Mader Stage 1
- Medullary: likely seen on MRI
- Hematogenous seeding
- Can be treated with antimicrobial therapy alone
104
Cierny and Mader Stage 2
- Superficial
- Contiguous spread
- Requires surgical intervention + systemic abx
105
Cierny and Mader Stage 3
- Localized
- Hematogenous or contiguous
- Requires surgical intervention + systemic abx
- Resection required
106
What is Cierny and Mader Stage 4?
- Diffuse osteo
- Requires surgical intervention + systemic abx
- Resection required
107
How is Osteomyelitis diagnosed?
Confirmation by imaging studies +/- growth of microorganism from bone biopsy or surgical sampling
108
What labs are abnormal in Osteomyelitis?
ESR and CRP elevated
109
What imaging studies are done for Osteomyelitis?
X-ray: quickest
MRI: gold-standard
110
Acute Osteomyelitis
- Onset: days to weeks
- Necrotic bone usually absent
111
Chronic Osteomyelitis
- Onset: weeks to months (may persist for years)
- Necrotic bone present
112
Age of Onset for Contiguous Osteomyelitis
Adults \> 50 yo
113
What is the age of onset like for Osteomyelitis due to vascular insufficiency?
Adults \> 40 years
114
What is the age of onset like for Hematogenous Osteomyelitis?
Mostly in children (age \< 20 yrs), adults \> 50 yrs
115
Sites of Infection in Contiguous Osteomyelitis
Femur, tibia, skull, mandible
116
What are the sites of infections for Contiguous Osteomyelitis?
Femur, tibia, skull, mandible
117
What are the sites of infections for Hematogenous Osteomyelitis?
Long bones (tibia and femur) in children
Vertebrae (spondylodiskitis) in adults
118
What are the risk factors for Contiguous Osteomyelitis?
- Trauma
- Surgery
- Insertion of joint prosthesis
- Cellulitis
119
What are the risk factors for Osteomyelitis due to vascular insufficiency?
- DM \> 10 yrs
- Poor glucose control
- Peripheral neuropathy
- Peripheral vascular disease
120
What are the risk factors for Hematogenous Osteomyelitis?
Bacteremia or endocarditis
121
What are the typical microorganisms that cause Contiguous Osteomyelitis?
Usually **polymicrobial**
Most common: **S. aureus**
122
What are the typical microorganisms that cause Osteomyelitis due to vascular insufficiency?
Usually **polymicrobial**
Most common: **S. aureus** and **Beta-Hemolytic Strep**
123
What are the typical microorganisms that cause Hematogenous Osteomyelitis?
Usually **monomicrobial**
**Neonates**: S. aureus, Group B Strep, E. coli
**Children**: S. aureus and S. pneumoniae
**Adults**: S. aureus and S. epidermidis
**Elderly**: GNRs
**IVDU**: P. aeruginosa
124
Duration of Antimicrobial Therapy for Osteomyelitis (**no surgical intervention**)
At least 6 weeks of IV abx
125
Duration of Antimicrobial Therapy for Osteomyelitis (**following radical resection of infected tissue of diabetic foot osteomyelitis)**
2-5 days
126
Duration of Antimicrobial Therapy for Osteomyelitis (**persistent infected or necrotic bone**)
At least 4 weeks
127
Duration of Antimicrobial Therapy for Osteomyelitis (**acute, hematogenous infection**)
At least 4-6 weeks of IV abx
128
Duration of Antimicrobial Therapy for Osteomyelitis (**chronic infection**)
Months (IV followed by PO)
129
What is the treatment for Hematogenous osteomyelitis like?
- S. aureus: cefazolin or oxacillin
- MRSA or S. epidermidis: Vancomycin
- GNB: 3rd gen ceph
130
What is the treatment for Contiguous or vascular insufficiency osteomyelitis like?
- Polymicrobial: Pip/tazo OR 3rd gen ceph + metronidazole or clindamycin
- Pseudomonas coverage: Pip/tazo, Ceftazidime or cefepime, Ciprofloxacin
