Neutrophil bactericidal function is defective in patients with recurrent urinary tract infections

Urinary tract infection (UTI), most frequently caused by Escherichia coli, is one of the most common bacterial infections in humans. It is a host inflammatory response to bacterial invasion in which large numbers of neutrophils are recruited into the bladder in response to cytokines secreted by the infected bladder epithelium. We hypothesise that an impaired host neutrophil response leads to susceptibility to recurrent UTI (rUTI). Therefore, the neutrophil inflammatory response of patients with a history of rUTI was compared to healthy controls. No difference in neutrophil adhesion receptor expression or complement receptor expression following bacterial stimulus was detected between the two groups. However, the expression of the IgG receptor CD16, bacterial phagocytosis and reactive oxygen intermediate (ROI) production were significantly reduced in UTI patient neutrophils compared to controls. Neutrophils from rUTI patients have a significantly reduced bactericidal function when compared to healthy controls, with the former showing a reduced capacity for activation. This reduced neutrophil function may result in defective bacterial clearance and lead to susceptibility to recurrent infection.