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Evidence for a staphylococcal-like mercury resistance gene in Enterococcus faecalis
1Program in Infectious Diseases and Clinical Microbiology, University of Texas Medical School, Houston 77030.
Antimicrobial Agents and Chemotherapy
|June 1, 1990
Summary
Mercury resistance was studied in Enterococcus faecalis clinical isolates. Eleven strains showed resistance, with mercury resistance genes transferable via plasmids, indicating potential spread.
Area of Science:
- Microbiology
- Environmental Health
- Genetics
Background:
- Enterococcus faecalis is a common cause of nosocomial infections.
- Mercury compounds are environmental pollutants with antimicrobial properties.
- Understanding mercury resistance mechanisms in bacteria is crucial for public health.
Purpose of the Study:
- To investigate the prevalence of mercury resistance (Hgr) in clinical isolates of Enterococcus faecalis.
- To determine if mercury resistance in these isolates is plasmid-mediated.
- To assess the transferability of mercury resistance genes.
Main Methods:
- Collection of 52 clinical Enterococcus faecalis isolates from two geographical regions.
- Testing isolates for resistance to mercury(II) chloride (HgCl2).
- Hybridization of plasmid DNA with a known staphylococcal mercury resistance gene probe.
- Conjugative transfer experiments to assess Hgr gene mobility.
Main Results:
- Eleven out of 52 (21%) Enterococcus faecalis isolates exhibited resistance to HgCl2.
- Plasmid DNA from mercury-resistant strains hybridized with the staphylococcal mercury resistance gene probe, suggesting genetic homology.
- Mercury resistance was successfully transferred from 5 of the 11 resistant strains to recipient strains via conjugation.
- Transfer frequencies ranged from approximately 2 X 10(-7) to 2 X 10(-3).
Conclusions:
- A significant proportion of clinical Enterococcus faecalis isolates harbor mercury resistance.
- Mercury resistance in these strains is likely plasmid-borne and transferable.
- The findings highlight the potential for mercury resistance genes to disseminate within bacterial populations, possibly contributing to broader antibiotic resistance.