RESISTANCE OF THE NORMAL HUMAN MICROFLORA TO MERCURY AND ANTIMICROBIALS AFTER EXPOSURE TO MERCURY FROM DENTAL AMALGAM FILLINGS

The concentrations of mercury in saliva and feces and the resistance p attern of the gastrointestinal microflora were investigated for 20 sub jects. Ten patients, with a mean number of 19 amalgam surfaces, had al l amalgam fillings removed during one dental session. Ten subjects wit hout amalgam fillings served as a control group, Saliva and fecal samp les were collected before amalgam removal and 2, 7, 14, and 60 days af terward. Mercury levels in saliva and feces correlated significantly w ith the number of amalgam surfaces. No differences in the resistance p attern of the oral microflora were detected between the two groups. In the amalgam group there was an increase in the relative number of int estinal microorganisms resistant to mercury, ampicillin, cefoxitin, er ythromycin, and clindamycin on days 7-14. This was not statistically s ignificant in light of the normal variations of the control group. A s ignificant correlation between the prevalence of mercury resistance an d multiple antimicrobial resistance in intestinal bacterial strains wa s observed.