"Mercury released from dental fillings provokes an increase in mercury and antibiotic resistant bacteria in oral and intestinal floras of primates", Antimicrobial agents and chemiotherapy

Summers AO, Wrieman J, Vimy MJ, Lorscheider FL, Martshall B, Levy SB,
Bennet S, Billard L,

"Mercury released from dental fillings provokes an increase in mercury and
antibiotic resistant bacteria in oral and intestinal floras of primates",
Antimicrobial agents and chemiotherapy, 37(4):825-834, 1993

ABSTRACT: In a survey of 640 human subjects, a subgroup of 356 persons without recent exposure to antibiotics demostrated that those with a high prevalence of Hg resisstance in their intestinal  floras were significantly more likely to also have resistance to two or more antibiotics. 

Resistances to mercury and to several antibiotics were examined in the oral and intestinal floras of six adult monkeys prior to the installation of amalgam fillings, during the time they were in place, and after replacement of the amalgam fillings with glass ionomer fillings (in four of the monkeys). The monkeys were fed an antibiotic free diet, and fecal mercury concentrations were monitorered. There was a statistically siginficant increase in the incidence of mercury-resistant bacteria  during the 5 weeks following installation of the amalgam fillings and during the 5 weeks immediately following their replacement. These peaks in incidence of mercuryresistant bacteria correlated with peaks of Hg elimination (as high as 1mM in the feces) immediately following amalgam placement and immediately after replacement of the amalgam fillings. Representative mercury-resistant isolates of three selected bacterial families (oral streptococci, enterobacteriaceae, and enterococcci) were also resistant to one or more antibiotics, including ampicillin.

Many of the enterobacterial strains were able to transfer mercury and antibiotic resistances together to laboratory bacterial recients, suggesting that the loci for these resistances are genetically linked. Our findings indicate that mercury released from amalgam fillings can cause an enrichment of mercury resistance plasmides in the normal bacterial floras of primates. many of these plasmids also carry antibiotic resistance, implicating the exposure to mercury from dental amalgams in an increased incidence of multiple antibiotics resistance plasmids in the non floras of non-medicated subjects.
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