It can be difficult to differentiate cellulitis from non-infectious mimics, like venous stasis. One way of determining the difference is feeling skin surface temperature. However, this is a subjective measure that is inherently unreliable. It might be possible to objectify this measurement by using a non-contact infrared thermometer at the bedside.

The goal of this study is therefore to assess whether objective difference in skin surface temperature in an area of suspected cellulitis, relative to non-affected skin, has diagnostic utility. It will use the diagnosis of cellulitis by an infectious diseases physician as the gold standard and compare blinded temperature difference between affected and unaffected limbs to that standard. It is hypothesized that measurement of skin surface temperature by non-contact infrared thermometer will help differentiate cellulitis from many non-infectious conditions that mimic cellulitis.

For patients who are hospitalized, the study also plans to see whether a change in this temperature difference is predictive of response to treatment when compared to the FDA standard for early response and patient reported symptoms.

This is a pragmatic, prospective cohort study. Patients with suspected cellulitis who receive an infectious diseases consult (in the emergency room or urgent clinic) will be approached for consent and enrollment. The goal is to enroll approximately 50 patients with a minimum of 10-15 cases of non-cellulitis.

These measurements will not be made available to the treating teams. This is an observational study only comparing the potential value of these measurements to usual clinical care.

Inclusion Criteria:

• Age 18 years or older;
• English or French-speaking;
• Received an infectious diseases consultation to evaluate proven or suspected cellulitis of the upper or lower extremity, either unilaterally or bilaterally;
• Either no empiric antimicrobials received or, at most, antimicrobials begun within 24 hours of notification for enrollment.

Exclusion Criteria:

• Presumptive diagnosis of a soft tissue infection of the trunk, head or neck that does not also involve a limb;

• Patients with only one limb;

• Patients with significant neuropathies or autonomic syndromes that might affect thermoregulation, such as severe diabetic neuropathy or diabetic dysautonomia, neurologic neoplasms and known vitamin deficiencies;

• Soft tissue infections requiring definitive surgical source control, such as abscesses or necrotizing fasciitis.

  • Septic arthritis

As above, our patient population includes patients aged 18 years and older who can communicate in English or French who receive an infectious diseases consultation for cellulitis of a limb.