RESUMO
Dermatologists may be over-ordering mycobacterial tissue cultures when performing the broad work-up of skin infection. The objective of this study was to determine mycobacterial tissue culture positivity in the work-up of suspected skin infection. This was a retrospective cohort study including patients biopsied for mycobacterial tissue cultures performed by dermatology providers from 2006 to 2020 in a large Midwestern US rural healthcare system. Main outcomes and measures were mycobacterial tissue culture positivity rates by body location, immunocompromised status, clinical setting, and exposure history. There were 552 mycobacterial tissue culture results from 515 patients, resulting in mycobacterial culture positivity in 13 cases (2.4%). Of these, 12 (92.3%) were outpatients, 9 occurred in immunocompromised patients (69.2%, P = 0.02), and 8 (61.5%) were from upper extremity lesion biopsies (P = 0.007). Lower extremity lesions were significantly associated with decreased mycobacterial culture positivity (P = 0.038). Trauma and environmental water exposures were not associated with mycobacterial tissue culture positivity. The rate of mycobacterial tissue culture positivity is low. Mycobacterial tissue cultures should particularly be targeted in patients who are immunocompromised and patients with upper extremity lesions. Automatic inclusion of mycobacterial tissue culture for skin infection work-up may not be necessary.
