The influence of heavy metals and antimicrobial on Staphylococcus aureus and Pseudomonas aeroginosa isolates

Abstract EN

Two isolates of Staphylococcus aureus and Pseudomonas aeroginosa of bacteria were exposed to different concentrations (5, 10 or 25 mg / l ) of heavy metals ions ( Silver Ag2+, Cobalt Co2+ or Lead Pb2+) for different exposure periods (0, 1, 2, 24 and 48 hrs.).

The results showed that the inhibitory effect of these metals on the growth of the two isolates were in the following sequences : Pb < Co < Ag Some of these metals caused an elongation of lag phase in liquid medium for these isolates.

Whene antibiotic discs (chloramphenicol 30 mcg, clindamycin 2 mcg, erythromycin 15 mcg, gentamycin 10 mcg, tetracycline 30 mcg and vancomycin 30 mcg) were added to solid medium which was previously supplemented with the above heavy metals ions, a synergestics effect was observed between antibiotics and heavy metals ions (specially silver ions at 25 mg / l) to increase the inhibition zone significantly (P < 0.01) for both isolates.