Co-occurrence of Heavy Metal and Antibiotics Resistance Traits in Bacteria Isolated from Poultry Droppings and Soil in Badagry, Lagos

Abstract

Background: Heavy metal and antibiotic resistance are two pressing global concerns affecting the agri-cultural and food sectors. Moreover, heavy metals tend to select antibiotic resistance in the absence of antibiotics. This study aimed to isolate, screen and identify heavy metal-resistant bacteria that can resist multiple antibiotics in agricultural settings. Methods: Using standard cultural techniques, twenty-six heavy metal tolerant bacteria were isolated from poultry droppings and soil samples collected from Lagos State Food Processing Centre located at Badagry, Lagos. The isolates were presumptively identified by their morphological characteristics and subjected to antibiotics sensitivity test using the disc diffusion method. The identities of isolates exhib-iting multi-drug resistance (MDR) among the metal tolerance isolates were authenticated using 16S rRNA gene sequence analysis. Results: All isolates recovered from the soil sample tolerated 3 mM of lead and nickel, while isolates from poultry droppings recorded the least tolerable concentrations of 1 mM and 2 mM of cadmium and lead, respectively. Each isolate exhibited resistance to at least a group of antibiotics phenotypically. Resistance to colistin (42.31%) was the highest among the isolates, closely followed by chlorampheni-col (23.08%), while gentamicin (3.85%) was the lowest among the isolates. However, six isolates were shown to be MDR strain, and they were identified as Bacillus pumilus, Bacillus cereus, Brevundimonas naejangsanensis, Pseudochrobactrum asaccharolyticum, Pseudochrobactrum saccharolyticum and Lysinibacillus xylanilyticus. Conclusion: This study further draws attention to the increasing dual resistance of bacteria to heavy metals and antibiotics, which may hinder the fight against antimicrobial resistance in agricultural set-tings