What signs of infection would be seen on physical exam?

Physical Examination Findings in Infection

The physical examination of a patient with infection will typically reveal signs of inflammation including fever, tachycardia, tachypnea, local warmth, redness (erythema), swelling (induration), tenderness, and purulent discharge at the site of infection. 1

Systemic Signs of Infection

Vital Signs

• Fever (temperature >38°C or >100.4°F) or hypothermia (<36°C)
• Tachycardia (heart rate >100 beats/min)
• Tachypnea (respiratory rate >20 breaths/min)
• Hypotension (systolic blood pressure <90 mmHg or >20 mmHg below baseline) - indicates potential septic shock 1

General Appearance

• Altered mental status or confusion
• Weakness or fatigue
• Diaphoresis (sweating)
• Malaise
• Rigors or chills 2

Local Signs of Infection

Skin and Soft Tissue Infections

• Erythema (redness) - often extending >0.5 cm around a wound in infection 1
• Calor (warmth) at the affected area
• Tumor (swelling or induration)
• Dolor (pain or tenderness)
• Purulent drainage - definitive sign of infection 1
• Skin breakdown or wound dehiscence 1
• Friable or discolored granulation tissue
• Foul odor from wound 1

Warning Signs of Severe Infection

• Pain disproportionate to physical findings
• Violaceous bullae (purple fluid-filled blisters)
• Cutaneous hemorrhage
• Skin sloughing
• Skin anesthesia (loss of sensation)
• Rapid progression of symptoms
• Gas in tissue (crepitus on palpation) 1

Specific Infection Types

Intra-abdominal Infections

• Abdominal pain and tenderness
• Abdominal distension
• Decreased or absent bowel sounds
• Rebound tenderness or guarding
• Rigidity 1

Diabetic Foot Infections

• Local swelling or induration
• Erythema around the wound
• Local tenderness
• Local warmth
• Purulent discharge 1

Fracture-Related Infections

• Wound breakdown
• Purulent drainage
• Sinus tract formation
• New-onset joint effusion
• Persistent or increasing wound drainage 1

Laboratory Findings Associated with Infection

While not physical examination findings, these are often evaluated alongside the physical exam:

• Leukocytosis (WBC >12,000/mm³) or leukopenia (<4,000/mm³)
• Left shift (>10% immature neutrophil forms)
• Elevated C-reactive protein (CRP)
• Elevated erythrocyte sedimentation rate (ESR)
• Elevated procalcitonin 1

Diagnostic Approach

When infection is suspected based on physical examination:

1. Assess severity using vital signs and systemic manifestations
2. Determine the extent of local inflammation
3. Consider specific infection types based on location and presentation
4. Obtain appropriate laboratory tests and imaging studies
5. Collect specimens for microbiological analysis when indicated 1

High-Risk Factors

Certain findings on physical examination should prompt immediate concern:

• Signs of systemic inflammatory response syndrome (SIRS)
• Evidence of organ dysfunction
• Rapidly spreading infection
• Crepitus or necrotic tissue
• Severe pain despite minimal findings 1

Remember that immunocompromised patients, elderly individuals, and those with diabetes may present with atypical or muted signs of infection, making diagnosis more challenging 1.