Inhibition of Blastomyces dermatitidis by topical lidocaine.

This study was designed to determine if lidocaine inhibited growth of Blastomyces dermatitidis and thereby reduced recovery of the fungus from bronchoscopy specimens. Case records of 36 patients with pulmonary blastomycosis showed that when the fungus was present at microscopy, whether the specimen was sputum or bronchial washings, culture of the bronchoscopic specimen was more frequently negative than the culture of the sputum specimen (p less than .05). In addition, lidocaine was shown to inhibit growth of B dermatitidis in vitro, with the inhibition depending on the concentration of the drug and the duration of exposure (p less than .01). High concentrations of lidocaine for topical anesthesia appear to adversely affect the recovery of B dermatitidis from bronchoscopic specimens.