Broader antibiotic coverage when systemic features present
Purulent and nonpurulent mimics
Purulent and nonpurulent mimics
Cellulitis without abscess
Diffuse erythema without focal fluctuance
POCUS without drainable collection
Furuncle and carbuncle
Follicular origin
Multiple draining points in carbuncle
Inflamed epidermoid cyst
Punctum
Keratinous material
Hidradenitis suppurativa flare
Axillary or groin distribution
Sinus tracts or scarring
Hematoma
Trauma history
POCUS heterogeneous clot appearance
Septic bursitis
Over bursa location
Preserved joint range compared with septic arthritis
Septic arthritis
Pain with passive range of motion
Effusion
Pyomyositis
Deep muscle pain
Systemic features
Necrotizing soft tissue infection
Rapid progression
Disproportionate pain
Herpes simplex or zoster
Vesicles
Dermatomal distribution
Coding alignment
Coding alignment
Cutaneous abscess ICD 10
L02 category by anatomic site
Cellulitis ICD 10
L03 category by anatomic site
Hidradenitis suppurativa ICD 10
L73.2
Necrotizing fasciitis ICD 10
M72.6
Fournier gangrene ICD 10
N49.3
When labs add value
When labs add value
Mild localized abscess without systemic features
Routine labs usually not required
Focus on source control
Systemic features or high risk host
Broader evaluation for sepsis
Baseline renal function for antibiotic selection
Necrotizing infection concern
Labs support risk stratification
Labs never exclude necrotizing infection
Core labs for complicated presentations
Core labs for complicated presentations
Complete blood count
Leukocytosis support for systemic infection
Neutropenia in immunocompromised host
Basic metabolic panel
Creatinine for dosing adjustment
Sodium for severe infection risk context
Serum glucose
Hyperglycemia as severity marker
Undiagnosed diabetes signal
C reactive protein
Trend support in severe infection
Limited specificity
Lactate
Elevated lactate supports hypoperfusion concern
Normal lactate does not exclude severe infection
Microbiology
Microbiology
Abscess material culture
Recurrent infection
Severe infection
Immunocompromise
Treatment failure
Blood cultures
Systemic toxicity
Immunocompromise
Suspected endovascular source
MRSA colonization testing
Recurrent disease evaluation context
Limited acute management impact
Scoring Systems
Scoring systems
SIRS criteria for infection severity
Temperature abnormality
Tachycardia
Tachypnea
White blood cell abnormality
qSOFA for sepsis risk stratification
Altered mentation
Systolic blood pressure 100 mmHg or less
Respiratory rate 22 or more
LRINEC for necrotizing infection risk context
C reactive protein
White blood cell count
Hemoglobin
Sodium
Creatinine
Glucose
LRINEC limitations
Low sensitivity in early disease
Not a rule out tool
Surgical evaluation priority over score
MRI
MRI indications and limits
Deep soft tissue infection mapping
Suspected pyomyositis
Suspected osteomyelitis near chronic wound
Necrotizing infection evaluation adjunct
Fascial edema patterns
Delay risk if unstable
Contraindications and barriers
Hemodynamic instability
Implanted device restrictions
Limited availability
CT
CT indications and limits
Deep space infection concern
Perirectal abscess mapping
Neck deep space infection mapping
Hand deep space infection mapping
Gas in soft tissues evaluation
Necrotizing infection concern
Clostridial myonecrosis concern
Contrast considerations
Renal dysfunction risk assessment
Allergy history context
CT limitations
Early necrotizing infection can have normal imaging
Imaging does not replace surgical consultation when high suspicion
Ultrasound
Ultrasound applications
POCUS for abscess versus cellulitis
Hypoechoic or anechoic collection
Cobblestoning pattern for cellulitis
Procedural guidance
Vessel and nerve avoidance
Deep collection localization
Foreign body detection
Radiolucent foreign bodies
Surrounding fluid collection
Ultrasound limitations
Overlying gas limits view
Operator dependence
Discharge criteria
Discharge criteria
Adequate source control
Successful drainage
No concern for deep extension
Clinical stability
Normal blood pressure
No persistent tachycardia after analgesia and fluids
No altered mental status
Pain control
Oral analgesia effective
Reliable follow up
Wound check in 24 to 48 hours when packing or high risk
Return precautions understood
Admission and higher level care criteria
Admission and higher level care criteria
Systemic toxicity
Persistent fever
Hypotension
Rising lactate
Rapid progression or extensive cellulitis
Expanding erythema despite initial therapy
Lymphangitis with systemic symptoms
High risk host
Significant immunocompromise
Uncontrolled diabetes
Neutropenia
High risk location or complexity
Face with orbital risk
Hand deep space concern
Perineal involvement
Perirectal abscess
Inadequate source control
Unable to drain at bedside
Multiloculated large abscess needing operative management
Failure of outpatient management
Worsening after 48 hours
Persistent or recurrent abscess despite appropriate therapy
Source control procedures
Source control procedures
Incision and drainage indications
Fluctuant abscess
POCUS confirmed fluid collection
Spontaneously draining abscess with retained cavity
Contraindications to bedside drainage
Pulsatile mass concern
Overlying vascular graft
Proximity to critical structures without imaging guidance
Technique essentials
Skin antisepsis
Adequate local anesthesia
Linear incision over point of maximal fluctuance
Blunt dissection to break loculations
Copious irrigation consideration
Drainage adjuncts
Loop drainage for select abscesses
Pediatric friendly option
Less packing discomfort
Packing considerations
Large cavity
Significant loculations
Avoid routine packing for small simple abscesses when not needed
Culture collection when indicated
Recurrent infection
Severe infection
Immunocompromise
Procedural analgesia and sedation
Regional block option by location
Digital block for finger lesions
Field block for larger lesions
Procedural sedation consideration
Large abscess
Severe pain or anxiety
Pediatric cooperation limitation
Antibiotics decision framework
Antibiotics decision framework
Incision and drainage alone often sufficient for uncomplicated abscess
Small localized abscess
No systemic features
Antibiotics adjunct indications
Systemic signs of infection
Extensive surrounding cellulitis
Multiple abscesses
Immunocompromise
Extremes of age
Difficult to drain location
Inadequate drainage or concern for deep extension
Recurrent abscess
Pathogen coverage targets
Community acquired MRSA coverage when purulent infection
Streptococcal coverage when significant nonpurulent cellulitis component
Polymicrobial coverage when perineal or bite associated infection
Oral antibiotics for outpatient therapy
Oral antibiotics for outpatient therapy
MRSA active options for purulent infection
Trimethoprim sulfamethoxazole
Adult dosing
Pediatric dosing
Key cautions
Doxycycline
Adult dosing
Pediatric dosing
Key cautions
Clindamycin
Adult dosing
Pediatric dosing
Key cautions
Streptococcal coverage when prominent cellulitis
Cephalexin
Adult dosing
Pediatric dosing
Amoxicillin
Adult dosing
Pediatric dosing
Combined strategy when both MRSA and streptococcal coverage needed
Trimethoprim sulfamethoxazole plus beta lactam
Trimethoprim sulfamethoxazole dosing as above
Cephalexin dosing as above
Doxycycline plus beta lactam
Doxycycline dosing as above
Cephalexin dosing as above
Clindamycin monotherapy option
Use when local MRSA susceptibility supports
C difficile risk context
Intravenous antibiotics for severe infection
Intravenous antibiotics for severe infection
MRSA coverage
Vancomycin
Initial dosing
Monitoring
Linezolid
Adult dosing
Key cautions
Daptomycin
Adult dosing
Key cautions
Ceftaroline
Adult dosing
Key cautions
Broad spectrum coverage when polymicrobial risk or necrotizing infection concern
Piperacillin tazobactam
Adult dosing
Key cautions
Cefepime plus metronidazole option
Cefepime
Metronidazole
Add clindamycin for toxin suppression when necrotizing infection concern
Adult dosing
Adjunctive care
Adjunctive care
Analgesia
Acetaminophen dosing per age and weight
NSAID use when no contraindication
Short course opioid only if severe pain and appropriate
Tetanus prophylaxis
Update based on immunization status and wound classification
MRSA decolonization for recurrent disease context
Intranasal mupirocin course consideration
Chlorhexidine body wash course consideration
Household hygiene measures
Wound follow up plan
Packing removal timing
Recheck timing 24 to 48 hours when high risk
Evidence levels and guideline style statements
Evidence levels and guideline style statements
Incision and drainage as primary therapy for uncomplicated cutaneous abscess
ACEP Level B recommendation
Adjunct antibiotics after drainage improve cure for some uncomplicated abscesses
ACEP Level B recommendation
Antibiotics indicated for abscess with systemic signs or extensive cellulitis
Class I recommendation
Ultrasound improves identification of drainable collections in equivocal exam
ACEP Level B recommendation
Necrotizing infection concern requires immediate surgical evaluation without imaging delay
Class I recommendation
Pregnancy
Pregnancy
Diagnostic considerations
Lower threshold for systemic evaluation when febrile
POCUS preferred when imaging needed
Antibiotic selection
Avoid doxycycline
Fetal tooth and bone effects concern
Trimethoprim sulfamethoxazole precautions
First trimester folate antagonism concern
Near term neonatal jaundice risk context
Preferred options when appropriate
Clindamycin when susceptible
Beta lactams for streptococcal coverage
Disposition considerations
Lower threshold admission with systemic features
Obstetric coordination when severe infection
Geriatric
Geriatric
Presentation differences
Blunted fever response
Atypical mental status changes
Medication considerations
Renal dosing adjustment need
Higher adverse effect risk
Disposition considerations
Lower threshold admission with frailty
Home wound care feasibility assessment
Pediatrics
Pediatrics
Procedure considerations
Topical anesthetic adjunct options
Sedation readiness for large painful lesions
Antibiotic dosing
Weight based dosing with max adult caps
Local MRSA susceptibility relevance
Return precautions emphasis
Worsening fever
Decreased intake
Lethargy
Disposition considerations
Lower threshold observation in infants with fever
Epidemiology
Epidemiology
Common emergency presentation within skin and soft tissue infections
Community acquired MRSA as frequent pathogen in purulent infections
Recurrent disease common in household clusters
Anatomic patterns
Follicular origin common in furuncles
Axillary and groin clustering in hidradenitis
Complication risk groups
Diabetes mellitus
Immunocompromise
Peripheral vascular disease
Pathophysiology
Pathophysiology
Localized collection of pus in dermis or subcutaneous tissue
Neutrophil accumulation
Liquefaction necrosis
Surrounding cellulitis
Inflammatory edema and bacterial spread in dermis
Lymphangitic involvement possible
Progression pathways
Spontaneous drainage
Extension to deeper fascia or muscle in severe cases
Microbiology patterns
Staphylococcus aureus common in purulent abscess
Streptococci common in nonpurulent cellulitis component
Polymicrobial organisms in perineal and bite associated infections
Therapeutic Considerations
Therapeutic considerations
Source control as key determinant of cure
Antibiotics alone inadequate for many abscesses without drainage
Antibiotic benefit strongest in selected groups
Systemic signs
Extensive cellulitis
High risk hosts
Larger lesions
Resistance and stewardship
Local antibiogram relevance
Narrowing therapy after culture when available
Procedure choices impact comfort and follow up needs
Loop drainage may reduce packing related pain
Routine packing not always beneficial for small simple abscesses
Harm prevention
Avoid incision over critical neurovascular structures
Imaging guidance for deep or high risk locations
Copy discharge instructions
Copy discharge instructions
Wound care
Keep dressing clean and dry for first 24 hours
Daily gentle washing after 24 hours
Warm compresses 10 to 15 minutes several times daily
Drainage expectations
Continued mild drainage for 24 to 72 hours can be normal
Sudden increase in swelling or pain after initial improvement needs reassessment
Packing or loop care when used
Follow up for recheck and removal in 24 to 48 hours
Do not remove at home unless instructed
Medications
Complete prescribed antibiotic course if given
Take pain medications as directed
Return to emergency care now for red flags
Fever or chills
Rapidly spreading redness
Worsening pain
Red streaking up the limb
New numbness or weakness near the site
Persistent vomiting or inability to keep fluids down
Confusion or fainting
Black or purple skin change
Severe pain out of proportion
Follow up
Primary care or wound check in 24 to 48 hours if packing used or high risk
Earlier follow up if symptoms worsen
Prevention
Avoid sharing towels or razors
Cover draining wounds
Hand hygiene
Clean high touch surfaces during outbreaks in household
Clinical guidelines and key sources
Clinical guidelines and key sources
Infectious Diseases Society of America guideline for skin and soft tissue infections
Purulent infection management with incision and drainage as primary therapy
Antibiotic selection based on severity and MRSA risk
Emergency medicine clinical policy topics for skin and soft tissue infection evaluation
Ultrasound utility for abscess identification
Antibiotics role after drainage in selected patients
Surgical principles for necrotizing soft tissue infections
Early surgical exploration priority when suspected
Broad spectrum antibiotics plus MRSA coverage when suspected
Antimicrobial stewardship principles for outpatient SSTI
Use local antibiogram for empiric choices
Narrow therapy when culture results available
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.