Occurrence of Heavy Metal and Antibiotic Resistant Bacteria in Soils from Selected Mechanic Workshops in Ibadan Metropolis, Nigeria

Aim: This study investigated the occurrence of antibiotic and heavy metal co - resistance in bacteria indigenous to mechanic workshops.

Study Design: The study is an experimental study.

Place: Samples were collected at mechanic workshop.

Methodology: Soil samples were collected from three mechanic workshops and tested for the presence of heavy metals. Hydrocarbon-utilizing bacteria was also isolated from the soils using Bushnell Haas medium supplemented with 1% engine oil or petrol. Isolates obtained were subjected to antibiotic resistance test and those that showed extensive drug resistance to the tested antibiotics were further tested for heavy metal resistance. Selected isolates were then identified using 16S rRNA gene sequence.

Results: The soil samples contained excessive amounts of Lead, Iron, Copper and Zinc, while the concentrations of Nickel, Cobalt, Cadmium and Chromium were within WHO permissible limit. A total of 10 hydrocarbon-degrading isolates were obtained from the soil samples, seven of which were gram negative and three were gram positive. Three of the isolates showed extensive drug resistance to 14 of the tested antibiotics. Three isolates were then subjected to heavy metal resistance test and all of them showed resistance to the tested heavy metals. They were identified and given ascension numbers as Stenotrophomonas maltophilia MW392903, Achromobacter xylosoxidans MW392904 and Pseudomonas aeruginosa MW392905.

Conclusion: It was observed that heavy metal resistance and antibiotic resistance can be selected for simultaneously as organisms adapt ways to cope with man’s activities in the environment, and while traits like hydrocarbon utilization and heavy metal resistance make the organisms promising in bioremediation, the inadvertent possession of antibiotic resistance by these environmental isolates poses a challenge to the health sector.