Abstract
The mercury and antibiotic resistance of 338 strains of Escherichia coli isolated from hospital patients was determined. Resistance to mercury was found in 58.6% of the isolates. The frequencies of resistance to streptomycin (Sm), tetracycline (Tc), chloramphenicol (Cm), kanamycin (Kan), cephaloridine (Cer), and gentamicin (Gm) were 66.3, 60.3, 56.5, 42.9, 32.1, and 1.5%, respectively. Among the above, 198 mercury- and antibiotic-resistant isolates were selected and tested for their ability to transfer the resistance to susceptible strains of E. coli K-12 and Klebsiella pneumoniae JK5. R plasmids carrying mercury resistance were demonstrated in 89.9% of the mercury-resistant strains of E. coli. Furthermore, R(Hg,Sm,Tc,Cm) plasmids were demonstrated most frequently, followed by R(Hg,Sm,Tc,Cm,Kan), R(Hg,Cm,Kan), and R(Hg,Sm,Tc,Cm,Kan,Cer) plasmids.