O. C. UDINYIWE

Clays have been utilized for centuries across various cultures for their therapeutic and medicinal properties, ranging from wound healing to antibacterial applications, owing to their adsorptive and chemical properties that inhibit pathogens and support tissue regeneration. This study was aimed at investigating the physicochemical and antibacterial properties of Okpepe clay, Uzala black clay and the combined effect of both clays on clinical isolates against some clinical isolates. Clay samples were processed into suspensions, physicochemical analysis was carried out to determine the pH, electrical conductivity (EC), total dissolved solids (TDS), heavy metal content and organic carbon. Uzala black clay had a higher pH (7.85), CEC (25.90 cmol/kg), and organic matter (2.80 %), while OKC was more acidic (pH 6.12) with higher EC and TDS. Antibacterial activity was tested against some clinical isolates such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Bacillus spp. using agar well diffusion at concentrations of 100 %, 75 %, 50 % and 25 %. Uzala black clay demonstrated superior antibacterial activity with larger zones of inhibition and lower MIC values (6.25 mg/mL against Staphylococcus aureus) compared to Okpekpe clay. Uzala black clay was bactericidal (MBC/MIC ≤ 2) against all isolates, while Okpekpe clay was often bacteriostatic. The clay combination (1:1) showed a remarkable synergistic effect, particularly at 75 % concentration, producing the largest zones of inhibition (42 mm against Pseudomonas aeruginosa). Uzala Black Clay is a potent, broad-spectrum bactericidal agent. The combination with Okpekpe Clay results in a significant synergistic enhancement of antibacterial efficacy. Its efficacy against clinical isolates, including those resistant to common antibiotics, highlights its potential as a source for developing new antimicrobial strategies against drug-resistant bacteria and its novel antimicrobial strategies.