ANTIBIOTIC SENSITIVITY PROFILE OF HYDROCARBONOCLASTIC BACTERIA ISOLATED FROM SOIL CONTAMINATED WITH SPENT PETROLEUM PRODUCTS

The unregulated release of spent petroleum products (SPPs) into the environment, particularly prevalent in developing nations like Nigeria, has led to extensive soil pollution, disrupting native microbial populations and encouraging the development of antibiotic resistance. This research examined the antibiotic susceptibility patterns of hydrocarbon-degrading bacteria isolated from SPP-polluted soils in Agbor, Delta State. Soil samples were obtained from both vehicle repair sites and uncontaminated (control) areas to allow comparative evaluation. The results showed that heterotrophic bacterial counts were significantly elevated in contaminated soils, indicating microbial adaptation to hydrocarbon-laden conditions. A broad spectrum of bacterial genera was identified, including Pseudomonas, Bacillus, Staphylococcus, Proteus, Shigella, and Enterococcus, with many isolates exhibiting multidrug resistance (MDR) to frequently administered antibiotics such as amoxicillin, streptomycin, and chloramphenicol. Resistance indices (R.I.) ranged between 0.3 and 0.8, surpassing the benchmark value of 0.2, which implies prior exposure to antibiotics or other selective agents in the environment. Plasmid profiling revealed that all isolates exhibiting high resistance carried large plasmids (greater than 10 kbp), suggesting that resistance traits may be plasmid-encoded. The study emphasizes the compounded risks posed by SPP contamination both in terms of long-term environmental degradation and the spread of antibiotic-resistant pathogens. These findings advocate for the implementation of stricter waste disposal policies, routine monitoring of environmental antibiotic resistance, and increased public education on the ecological and public health implications of uncontrolled hydrocarbon pollution.