Infectious diseases and the kidney in children

Abstract

The kidney is involved in a wide range of bacterial, viral, fungal, and parasitic diseases. In most systemic infections, renal involvement is a minor component of the illness, but in some, renal failure may be the presenting feature and the major problem in management. Although individual infectious processes may have a predilection to involve the renal vasculature, glomeruli, interstitium, or collecting systems, a purely anatomic approach to the classification of infectious diseases affecting the kidney is rarely helpful because most infections may involve several different aspects of renal function. In this chapter, a microbiological classification of the organisms affecting the kidney is adopted. Although they are important causes of renal dysfunction in infectious diseases, urinary tract infections and hemolytic uremic syndrome (HUS) are not discussed in detail because they are considered separately in chapters XX and XX, respectively. The kidney is involved in a wide range of bacterial, viral, fungal, and parasitic diseases. In most systemic infections, renal involvement is a minor component of the illness, but in some, renal failure may be the presenting feature and the major problem in management. Although individual infectious processes may have a predilection to involve the renal vasculature, glomeruli, interstitium, or collecting systems, a purely anatomic approach to the classification of infectious diseases affecting the kidney is rarely helpful because most infections may involve several different aspects of renal function. In this chapter, a microbiological classification of the organisms affecting the kidney is adopted. Although they are important causes of renal dysfunction in infectious diseases, urinary tract infections and hemolytic uremic syndrome (HUS) are not discussed in detail because they are considered separately in Chaps.​ 47, “Renal Involvement in Children with HUS,” and 53, “Urinary Tract Infections in Children,” respectively. Elucidation of the cause of renal involvement in a child with evidence of infection must be based on a careful consideration of the geographic distribution of infectious diseases in different countries. A history of foreign travel; exposure to animals, insects, or unusual foods or drinks; outdoor activities such as swimming or hiking; and contact with infectious diseases must be sought in every case. The clinical examination should include a careful assessment of the skin and mucous membranes and a search for insect bites, lymphadenopathy, and involvement of other organs. A close collaboration with a pediatric infectious disease specialist and hospital microbiologist will aid the diagnosis and management of the underlying infection. A tantalizing clue to the pathogenesis of glomerular disease is the marked difference in the incidence of nephrosis and nephritis in developed and underdeveloped areas of the world. In several tropical countries, glomerulonephritis (GN) accounts for up to 4 % of pediatric hospital admissions; the incidence in temperate climates is 10- to 100-fold less. This difference might be explained by a complex interaction of several different factors, including nutrition, racial and genetically determined differences in immune responses, and exposure to infectious diseases. A growing body of evidence, however, suggests that long-term exposure to infectious agents is a major factor in the increased prevalence of glomerular diseases in developing countries. Renal involvement in infectious diseases may occur by a variety of mechanisms: direct microbial invasion of the renal tissues or collecting system may take place in conditions such as staphylococcal abscess of the kidney occurring as a result of septicemic spread of the organism; ascending infection commonly occurs due to infection in the urinary tract; damage to the kidney may be caused by the systemic release of endotoxin or other toxins and activation of the inflammatory cascade during septicemia or due to a focus of infection distant from the kidney; ischemic damage may result from iuate perfusion induced by septic shock; the kidney may be damaged by activation of the immunologic pathways or by immune complexes resulting from the infectious process. In many conditions, a combination of these mechanisms may be operative. In the assessment of renal complications occurring in infectious diseases, the possibility of drug-induced nephrotoxicity caused by antimicrobial therapy should always be considered. The nephrotoxic effects of antibiotics and other antimicrobial agents are not addressed in this chapter but are covered in Chap.​ 67, “Handling of Drugs in Children with Abnormal Renal Function”.