Risk Factors For Bacterial Infection Research Articles

Risk factors for infection and immunoglobulin replacement therapy in adult nephrotic syndrome.

Infection has been recognized as an important cause of morbidity and mortality in children with nephrotic syndrome. However, the incidence and severity of infection and the mechanisms responsible for the increased susceptibility to infection are still unclear in adults. We studied 86 consecutive adult patients with nephrotic syndrome but no diabetic nephropathy. Risk factors for infection were evaluated by logistic regression analysis. Infections were found in 16 patients (19%), of whom six died of infection and two developed end-stage renal failure associated with infection. The relative risk for bacterial infection among patients with serum immunoglobulin G (IgG) levels below 600 mg/dL was 6.74 compared with that for patients with serum IgG levels over 600 mg/dL (95% confidence interval, 1.22 to 36.32; P = 0.029). In patients with serum creatinine levels over 2.0 mg/dL, the relative risk of bacterial infection was 5.31 compared with patients with serum creatinine levels below 2.0 mg/dL (95% confidence interval, 1.08 to 26.09; P = 0.040). Intravenous immunoglobulin (10 to 15 g) was administered prospectively every 4 weeks to 18 patients with serum IgG levels below 600 mg/dL until serum IgG levels increased to over 600 mg/dL. Administration of immunoglobulin resulted in a decreased rate of bacterial infections to a level equal to that in patients with endogenous levels over 600 mg/dL. These data indicate that hypogammaglobulinemia and renal insufficiency are independent risk factors for bacterial infection in adult patients with nephrotic syndrome. The effects of intravenous immunoglobulin suggest that maintenance of serum IgG levels over 600 mg/dL may reduce the risk of infection.

Serum C‐reactive protein is a useful marker for congenital infection

Serial quantitative measurements of C‐reactive protein (CRP) were performed by reaction rate nephelometry on cord blood and scrum of 70 babies (60 preterm and 10 full term). There were 41 babies born to mothers with no risk factors for bacterial infection (Group 1) and 29 babies born to mothers with risk factors (Group 2), Maternal risk factors for congenital infection were: a history of prolonged rupture of membranes, maternal treatment with antibiotics, chorioamnionitis or positive cultures from high vaginal swabs. Twelve babies had raised CRP levels (>10 mg/1), 2 from Group 1 and 10 from Group 2, 9 of whom were subsequently found to have bacterial infections. One of the 2 babies without suspected infection had severe birth asphyxia. Specificity, sensitivity, positive and negative predictive values were calculated for CRP levels and total white cell counts (TWCC). Within Group 2, the specificity of raised CRP for diagnosis of congenital bacterial infection was 95% and the sensitivity was 100%, compared to the specificity of TWCC 95% and sensitivity 55%. CRP can be used as a marker for congenital bacterial infection and appears to be more sensitive than TWCC.

Complement Deficiency and Neutrophil Dysfunction as Risk Factors for Bacterial Infection in Newborns and the Role of Granulocyte Transfusion in Therapy

The similarity in the susceptibility to bacterial infections of newborns and older patients with complement deficiencies, neutropenia, or neutrophil function defects has suggested that neutrophils and/or complement might also be defective in newborns. Although no individual element of the phagocytic host defense system is severely deficient, several partial deficiencies have been identified. These involve important amplification pathways of complement and neutrophil activation and may combine to cause significant decreases in phagocyte activity at sites of infection. Because of decreased specific antibody, initial activation of the classical complement pathway is decreased. Low levels of C3 and factor B decrease amplification by the alternative pathway and result in marked decreases in opsonization and generation of chemotactic activity from C5. There are also quantitative and qualitative neutrophil defects. The recent observations that newborns' neutrophils are relatively deficient in membrane expression of their major adherence protein/C3bi receptor help explain the decreased mobility and phagocytic activity of these cells. Thus, several partial deficiencies combine to cause severe impairments in delivery of neutrophils to sites of infection and contribute to the increased susceptibility of the newborn to infection.