Effect of lidocaine on the growth of Mycobacterium tuberculosis in liquid culture medium

Pneumologists use topical anesthetic agents such as lidocaine during bronch oscopic examinations or to collect samples for mycobacterial research. The authors have assessed the effect of lidocaine on the growth of Mycobacteriu m tuberculosis inoculated in liquid culture medium, using a radiometric met hod. A high concentrations of lidocaine (5 %) inhibits mycobacterial growth . Lower concentrations (0.5 % and I %) increase the delay of growth, and a 1 % concentration of lidocaine inhibits the lower inocula growth. Lidocaine concentrations that are recovered in bronchoscopic specimens are inferior to I %. After direct inoculation into the culture medium, the lidocaine con centration is inferior to 0.05 % and only the growth delay increases.