Anti-bacterial and anti-fungal effect of several anti-rheumatic drugs.

The strong microbicidal activity of gold compounds towards Helicobacter pylori (HP) has been recently demonstrated in vitro, raising its potential clinical therapeutic application. Accordingly, we investigated the in vitro activity against fungi and bacteria of anti-rheumatic drugs (auranofin, GST, d-penicillamine, bucillamine, and salazosulfapyridine) . For the assessment of anti-bacterial and anti-fungal activity, an agar dilution test was performed. In brief, 25.6mg of each drug was dissolved in 1 ml of dimethyl sulf oxide, and then the minimum bactericidal concentration and the minimum fungicidal concentration (MIC) were determined by inhibition of the visible growth of organisms during subsequent incubation for 48hrs at 37°C.Auranofin was found to show some activity against 3 strains of Staphylococcus (S) (S. aureus 1, ug/ml, MRSA 8μg/ml, S. epidermidis 0.5μg/ml), 7 strains of Streptococcus, 2 strains of Enterococcus, 4 strains of clostridium and Candida albicans (4 μg/ml) . A weak activity of GST against gram (-) bacterias was also recognized, but the other antirheumatic drug did not show any anti-bacterial activity.The mechanism of the antibacterial and antifungal activity of gold compounds is not known, but it is possible to speculate that gold compounds usually combined with active chemical sulfhydryl groups on proteins including enzyme and these binding caused the death of bacteria.