Environmental heavy metals and Staphylococcus aureus resistance: insights from Nigerian cities

Growing evidence suggests that antimicrobial resistance may be influenced by environmental pollutants, particularly heavy metals such as lead (Pb), cadmium (Cd), and copper (Cu), which exert co-selective pressures that favor the emergence of resistant strains. This study explored the relationship between environmental heavy metal exposure and nasal colonization by MRSA and methicillin-susceptible Staphylococcus aureus (MSSA) in urban Nigerian communities. Eighty participants provided blood samples and nasal swabs. Staphylococcus aureus strains were isolated and identified using standard microbiological techniques. Blood samples were analyzed for Pb, Cd, and Cu concentrations using atomic absorption spectrophotometry. Port Harcourt recorded the highest Cu levels, whereas Aba showed the highest blood concentrations of Pb and Cd (0.042 ± 0.006 and 0.041 ± 0.004 mg dL^-1, respectively). A significant gender-specific difference in Cu exposure was observed, with male participants in Aba exhibiting notably higher levels (0.071 ± 0.030 mg dL^-1, P = 0.002). Strong positive associations were identified between MRSA colonization and blood Pb (r = 0.72, P < 0.01) and Cd levels (r = 0.68, P < 0.01). Conversely, MSSA colonization was negatively associated with heavy metal concentrations (r = -0.54, P < 0.05), suggesting that metal pollution may preferentially support the proliferation of resistant strains.