Fig. 2. Symptomatic infections and asymptomatic bacteriuria.
a | Acute pyelonephritis is a severe bacterial infection localized to the kidneys with systemic involvement and considerable mortality. Spread of bacteria to the blood stream (urosepsis), occurs in about 30% of adults20–23. Infection gives rise to an innate immune response and local inflammation in the kidneys, as well as systemic spread of pro-inflammatory mediators, which cause fever, general malaise and activate the acute phase response. b | Acute cystitis is an infection of the urinary bladder and lower urinary tract. An often potent, inflammatory response causes bladder oedema, hyperaemia and pyuria, and patients experience pain, dysuria and increased frequency. c | However, bacteriuria is not always accompanied by inflammation and disease. In asymptomatic bacteriuria, the urinary tract is colonized by bacteria without evidence of disease. This condition is defined by repeated positive urine cultures in an asymptomatic patient. CRP, C-reactive protein.