Estudo da patogênese das infecções urinárias por Streptococcus agalactiae em modelo murino de diabetes induzida

Abstract

Streptococcus agalactiae, also known as group B Streptococus (GBS), are Gram-positive cocci that grows in pairs or in chains. GBS has emerged as an important cause of invasive infection in non-pregnant adults, although the reasons for the increased incidence of GBS disease are not fully understood. Medical conditions, including changes in the immune response, are the major risk factors for the GBS infections, particularly diabetes. The prevalence of diabetes among patients with invasive GBS disease is higher (44.4%) than the non-diabetic population. Urinary tract infections are the most common bacterial infections in humans, causing a great expense to public and private health systems. GBS is responsible for 11 million consultations/year in the United States with annual costs of 6 billion dollars. Therefore, the present study aimed to standardize intraperitoneal and intranasal infection of diabetic murine model by GBS, analyzing the development of pathogenesis in the urinary tract. The diabetes induction was performed through the intraperitoneal administration of streptozotocin drug, after confirmation of hyperglycemia, the animals were infected intranasally by GBS90356 strain and intraperitoneally with GBS90356, COH1, GBS90356bspC strains (1x107 UFC/mL). The animals were euthanized in the chronic infection model (5 weeks) and after in the acute infection model (5 days) for the removal of target organs (kidney and bladder), as well as urine and blood to count viable colonies (CFU/mL) for dissemination analysis, growth and bacterial persistence. In the chronic model, bacterial growth was higher in diabetic infected (DI) group than in the non-diabetic infected (NDI) group. In the same way, this infection model showed a significant CFU/mL count in fluids, urine and blood; in contrast, the acute model, presented bacterial count only in the kidney and bladder. In addition, GBS90356 strain showed amplification for all virulence factor genes tested, with exception for PI-2a. The biofilm formation of GBS strains recovered from diabetic animals changed in the presence of hyperglycemic environmen. Therefore, both infection models tested were successful, presenting bacterial counts in different animal groups, demonstrating that the models are replicable for urinary tract infection due to GBS in a murine model of induced diabetes