Pyelonephritis and Bacteriuria

Abstract

The changing pattern of infectious disease is well illustrated in the problem of pyelonephritis. In the past, clinically important infections were due largely to microorganisms that were "caught," that is, were not indigenous to the host. Socioeconomic patterns played important roles in determining the prevalence and pathogenesis of such infections. Now, increasing numbers of infections are due to gram-negative rods, staphylococci, enterococci, and similar microorganisms that are not "caught" in the usual sense of the word, but are constantly present within the host. The presence of such organisms, and their capacity to cause clinical disease, seem to be influenced less by specific socio-economic circumstances than by subtle changes in the equilibrium between host and parasite. The very fact that this equilibrium is constantly operative and constantly subject to change makes it especially likely that autochthonous organisms will be associated with chronic infections as well as with acute symptomatic disturbances. The nature of chronic disease presupposes that relatively asymptomatic states of disease will precede the appearance of clinically manifest illness, and that, therefore, there are likely to be many more instances of chronic disease in the population at large than would be recognized in hospitals on the basis of arbitrary clinical criteria. The exploration of bacteriuria and of pyelonephritis using the simple colony count of voided urine as a tool has led to many more problems than it has solved. However, there is now clear evidence that bacteriuria is one of the commonest human infections, that it may be chronic and persistent, that it may influence structure and function outside of the urinary tract, and that it plays an important role in disease from the cradle to the grave- from prematurity to hypertension and renal failure.