Isolation of silver- and antibiotic-resistant Enterobacter cloacae from teeth

Oral Microbiol Immunol. 2005 Jun;20(3):191-4. doi: 10.1111/j.1399-302X.2005.00218.x.


Antibiotic-resistant bacteria pose a serious threat to human health; hence the mechanisms that lead to their selection need to be investigated. One possible mechanism is that the silver and mercury in amalgam dental restorations may select for bacteria that contain heavy metal and antibiotic-resistance determinants, leading to the spread of these resistances, particularly if they are contained on the same mobile genetic element. The incidence of silver-resistant bacteria on teeth is investigated in this work. Two silver-resistant Enterobacter cloacae isolates were isolated from infected teeth containing dental restorations. Both isolates were also resistant to ampicillin, erythromycin, and clindamycin. The silE gene, which is encoded on the silver resistance operon, has been sequenced from both isolates. Results suggest that the silver resistance operon is encoded on plasmid DNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Dental Amalgam / chemistry
  • Drug Resistance, Bacterial* / genetics
  • Enterobacter cloacae / drug effects*
  • Humans
  • Silver / pharmacology*
  • Tooth / microbiology*


  • Silver
  • Dental Amalgam