Visualization of doxycycline in lung tissue and sinus secretions by fluorescent techniques.

The two studies which are reviewed in this paper demonstrate the value of fluorescent microscopic observations in the studying of the distribution of antibiotics in lung tissue and in sinus secretions. In the lung tissue study, the standard microbiologic assay data on doxycycline concentrations in respiratory tissue take on greater meaning when one is able to visualize the relative distribution of doxycycline-derived fluorescence among bronchiolar, vascular and parenchymal sites. In the sinus secretions study, doxycycline was shown to pass into the sinus secretions in concentrations, in most instances, which are significantly greater than the relevant MICs. These therapeutic levels were achieved and assayed in sinus secretions, even though a corresponding fluorescence was not always demonstrated. When fluorescence was shown, the wide homogeneous distribution of doxycycline throughout the aspirate of purulent maxillary sinus mucus was striking. Fluorescent microscopy can provide a dynamic visualization of doxycycline's presence in human tissue and secretions. Fluorescent microscopy, together with standard microbiological assay methods, affords both qualitative and quantitive data on the drug's biologic activity.