HEAVY METAL RESISTANCE AND ANTIBIOTIC RESISTANCE IN HOSPITAL ISOLATES OF STAPHYLOCOCCUS AUREUS FROM KARACHI
One hundred and five hospital strains of Staphylococcus aureus isolated from in-patients and out-patients were examined for sensitivity to heavy-metal ions i.e. cadmium and mercury. Strains were also tested for resistance to antibiotics and the nucleic-acid-binding compounds, ethidium bromide. In the hospital strains of S. aureus, resistance to cadmium ion at 50µg/mL was found to be 77% and resistance to mercury at 10µg/mL was found 20%. No strain was found to be resistant to mercury at 50µg/mL. Mercury resistance was found to be low as compared to cadmium. A high number of ethidium bromide resistance isolates were found which have been classified as multi-drug resistances as well on antibiotic resistance. Majority of these strains were resistance to more than three different classes of antibiotics and antibiotype KTPG was most prevalent. The curing studies showed the association of cadmium resistance to plasmid but not for the ethidium bromide resistance. Resistance found to be frequently cured among the tested strains was kanamycin followed by gentamicin. As the heavy metal resistance microorganisms has significant role in the detoxification of polluted environment but the spread of this resistance to the multidrug resistance S. aureus is alarming.