Aim: The current study investigated the prevalence and molecular relatedness between Escherichia coli O157:H7 isolated from water, meat and meat products and vegetables and from stools of confirmed and non-confirmed Human Immune Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS) patients with diarrhoea. Methods and Results: Culture-based and polymerase chain reaction techniques were used to identify E. coli O157:H7. Thirty-five per cent of meat products, 25.5% of water, 21.7% of vegetables as well as 56.5% and 43.5% of stools of confirmed and non-confirmed HIV/AIDS patients, respectively, were presumptively positive with E. coli O157. Molecular results indicated that 10.3%, 8.6% and 7.8% of the vegetables, water and meat products examined carried E. coli O157:H7, which had homologous fliC(H7), rfbE(O157) and eaeA genetic loci to the genes of some E. coli O157:H7 isolated from 12.2% and 8.8% of the stools of confirmed and non-confirmed HIV/AIDS patients, respectively. Conclusions: Water, meat and meat products and vegetables are potential sources of E. coli O157:H7 that are potentially capable of causing diarrhoea in humans especially HIV/AIDS patients. Significance and Impact of the Study: Great care should be exercised to ensure that water and foods consumed by HIV/AIDS patients are safe, as contaminated water and foods can cause secondary infections in these patients.