Synergistic increase in antibiotic resistance with tolerance to cadmium and lead in environmental bacteria isolated from the San Cristobal River, Laguna De Bay, Philippines
Kikongo Marie-Médiatrice Ntabugi, Bahati J. Manegabe, John Barr Dewar, Jessica Simbahan, Maxima E. Flavier, Christian B. Sekomo
Abstract
Pollution increases bacterial tolerance to heavy metals and antibiotic resistance. San Cristobal River sediment and water samples were analysed for Cadmium (Cd) and Lead (Pb). Isolates of Salmonella spp. and Vibrio spp. were tested for tolerance to metals and resistance to five different classes of antibiotics. Isolates showing tolerances to Cd were linked to increased resistance to antibiotics (76.5%) compared to Pb-tolerant isolates (66%). Tolerance to both Cd and Pb further increased antibiotic resistance (p < 0.05). Cd-tolerance correlated with resistance to Amp, Sxt and Cip while Pb tolerance correlated with resistance to C, Amp and Cip. These results support a bacterial mechanism whereby transfer of plasmids expressing metal tolerance promotes increased antibiotic resistance.