Resistance to antibiotics of heavy metal‐tolerant and heavy metal‐sensitive bacterial strains

Abstract

Seventy‐three bacterial isolates from polluted streams as well as 157 of their heavy metal‐tolerant (HM‐tolerant) derivatives were tested for their sensitivity to ampicillin, ticarcillin, gentamicin, cephalexin, sul‐famethoxazole, tetracycline and colistin. Among the parent strains 19% were sensitive to all antibiotics tested and 70% were multiple resistant. The mean resistance of parent strains was 227 antibiotics per isolate. Mean resistance was increased to 2.82 for silver‐, 3.32 for gold‐, 3.48 for copper‐, 3.78 for nickel‐, and 3.79 for cadmium‐tolerant subcultures. A statistically significant increase in resistance was demonstrated for tetracycline and sulfamethoxazole in all HM‐tolerant subcultures, for cephalexin in gold‐, nickel‐ and cadmium‐ tolerant strains, for ampicillin in gold‐tolerant isolates and for ticarcillin in cadmium‐tolerant strains.