Abstract Background and Objectives ABO blood group antigens with carbohydrate molecules are found on the surface of uroepithelial cells, which influence human susceptibility to infectious diseases. The present study tries to determine the relation between these antigens and the type of the urinary tract pathogens. Materials and Methods In this descriptive study, 250 patients whose urinary tract infection had been confirmed by pyoria and positive urine culture were studied. Sampling method was continued until at least 30 patients from different blood groups were involved. A questionnaire addressing age, sex, blood group type, and type of UTI pathogen was filled out for each patient. Data were analyzed by SPSS 13, chi-sqaure, and fisher test. Results The results showed E.coli as the most prevalent type of the urinary tract pathogen in B and O blood groups with the rates of 72.7% (CI95%= 54.08 - 91.32 ) and 52.3% (CI95% = 41.54 - 63.06), respectively. Staphylococcus saprophyticus was also the most prevalent pathogen in blood groups A and AB with the rates of 43% (CI95%= 30.1 - 50.9) and 39% (CI95%= 16.48 - 61.52), respectively. The correlation between urinary tract pathogens and blood groups was significant (p<0.05). However, urinary tract pathogens had no significant correlation with sex and age. Conclusions E.Coli is the most common known cause of UTI however, it is Staphylococcus saprophyticus being the most common pathogen in blood groups A and AB. � Key words : Blood group antigens, UTI, E.coli, Staphylococcus saprophyticus |