Isolation of the strains:
Antibiotics resistant strains were obtained by the method of ten-fold serial dilution and screened
by inoculating on to Mueller–Hinton agar media added with 1.0 µg/mL of antibiotics
(tetracycline or amoxicillin or norfloxacin or cefradine) and heavy metals (10 µg/mL of Pb2+ or Cr(VI) or Hg2+ or Cu2+ or Zn2+). After an incubation of 24 h at 37°C, morphological observations were recorded
and biochemical tests were done on bacterial isolates.