Screening of Heavy Metals Tolerance among Beta-Lactamase Producing Bacteria from Contaminated Soil and Waste Water of Some Abattoirs in Adamawa State

Bacterial adaptability enables them to tolerate various stresses, including those from antibiotics and heavy metals. This study aims to investigate the tolerance to heavy metals, as well as the production of beta-lactamase and metallo-beta-lactamase, in bacterial isolates from abattoir-contaminated sites in Adamawa State. Samples were analyzed using standard microbiological techniques. Bacterial isolates with a MAR index above 0.4 were screened for tolerance to heavy metals (Cu, Zn, Fe, Co, and Pb) at concentrations of 50, 150, and 300 ppm, respectively. Extended-spectrum β-lactamase activity (ESBL) was detected on Mueller-Hinton agar using the Kirby-Bauer double disk diffusion method. Metallo-beta lactamase activity was determined using Imipenem (IMP) – EDTA Combine disc. All isolates exhibited varying levels of growth, except for Chromobacterium spp., which showed no growth at any concentration. However, Pseudomonas aeruginosa and Escherichia coli were able to grow in the presence of all heavy metal concentrations, except for zinc at concentrations of 150 and 300 ppm. Extended-spectrum β-lactamase (ESBL) production and the detection of metallo-β-lactamase activity showed that the isolates were positive for the test at different intensities, with respect to the clarity of the zones; however, Pseudomonas aeruginosa and Escherichia coli had the highest zones (> 5 mm) with amoxicillin-clavulanic acid. Some were positive for metallo-β-lactamase activity, but at different levels with respect to the clarity of the zones. E. coli showed the highest increase in zone with an Imipenem (IMP) EDTA disk of> 7 mm, followed by P. aeruginosa. These potentials can give prior information about the two isolates with respect to the hazard they present in the immediate environment.