The anti-inflammatory drug Diclofenac retains anti-listerial activity in vivo

Aims: The interactions between nonsteroidal anti-inflammatory drugs (NSAID) and Listeria monocytogenes have not been sufficiently documented to date. The aim of this study was to investigate the possible effects of Diclofenac (Dc) in a murine listerial infection model. Methods and Results: Dc was administered orally at 2.5 mu g g(-1) to female albino strain of laboratory mouse (BALB/c) thrice postinfection (1 x 10(8) CFU ml(-1) oral challenge with L. monocytogenes ATCC 51774), which resulted in significantly (P < 0.01) reduced bacterial counts in liver and spleen, decreased (10-fold, P < 0.05) hepatic colonization and necrosis, and caused up-regulation of the expression of inflammatory cytokines (interferon-gamma, interleukin-1 beta, tumour necrosis factor-alpha), compared with drug-free control. Conclusions: Dc may be useful as a promising adjuvant to the existing therapies in controlling systemic listerial infection. Further, quantitative structure-activity relationship studies might contribute in manipulating it as a lead compound for the synthesis of new, more effective nonantibiotics, perhaps, devoid of side-effects that could be recommended as a compassionate therapy for listeriosis. Significance and Impact of the study: This is the first in vivo study designed to evaluate the antilisterial effect of the NSAID Dc with special emphasis on the immunological mechanism of action of the drug.