The severity of an infection is a function of the resistance of the host and the virulence of the infecting strain. Infections of the urinary tract can be caused by a wide range of gram-negative and gram-positive bacteria, which also are constituents of the normal flora. Indeed, most uropathogens originate from the intestinal tract. Still, the virulence concept implies that bacteria associated with urinary tract infections differ from members of the indigenous flora not causing infections. This review attempts to summarize the mechanisms known to contribute to bacterial virulence in the urinary tract and their relevance in different patient groups.
Endotoxin [lipopolysaccharide (LPS)] from Gram-negative bacteria is found in amniotic fluid in intrauterine infections that associate with the risk for spontaneous premature birth, bronchopulmonary dysplasia (BPD), and respiratory distress syndrome. Toll-like receptor 4 (TLR4) is the signaling receptor for LPS. The aim was to investigate the primary inflammatory response in mice shortly after administration of LPS to the dam (14 and 17 d of pregnancy), to the newborn, or into the amniotic fluid. The expression levels of TLR4, IL-1, tumor necrosis factor-alpha, IL-6, IL-10, macrophage inflammatory protein-2, and IL-1 receptor 1 were studied with ribonuclease protection assay. In addition, TLR4 protein was analyzed with Western blotting. The fetal membranes expressed TLR4 mRNA and protein and showed an acute cytokine response to LPS when LPS was administrated into the amniotic fluid. There was distinct ontogeny in the responsiveness of fetal lung to LPS: on fetal day 14 (term 20 d), both the expression of TLR4 and the acute cytokine response were undetectable 5 h after LPS; they became detectable by fetal day 17. TLR4 and the cytokine response further increased after birth. In maternal lung, the TLR4 expression was strongest and up-regulated in parallel with the induction of the cytokines. We propose that TLR4 controls the magnitude of the LPS-induced cytokine response during the perinatal period.
Analysis of the immunological reactivity conditions of burned children was conducted. The factors witch have influence on the functional activity of blood leucocytes were studied. The decrease of immunological reactivity proportionale to the grave of the trauma was discovered. The secondary immunodeficiency in T-indepent type developed. The protein fraction of the blood serum influenced on the T-lymphocytes to the highest degree. Simultaneously decrease of the toleranse to the autologus erytrocytes with the hyperproduction of antibodies was discovered.