Análise da microbiota de feridas cirúrgicas em maxilas de ratos sob terapia com bisfosfonatos

Abstract

Bisphosphonates are drugs widelly used to treat diseases characterized by intense bone resorption. Although very efficacious, they are also associated with cases of osteonecrosis in jaw bones called bisphosphonate-related osteonecrosis of the jaws (BRONJ). The disease is difficult to treat and its etiology is considered multifactorial but it has not yet been completely understood. Among other etiologic factors, the major or secondary role of microorganisms in BRONJ has been discussed. The aim of this work was to evaluate by means of histomorphometry in Gram, Gomori-Grocott and immunohistochemistry (IHC) the microorganisms found in surgically induced wounds in maxillae of rats subjected to bisphosphonate therapy. Thirty-four rats were allocated into three groups according to the treatment received: (1) zoledronic acid group (n=12); (2) clodronate group (n=12); and (3) control group (n=10, normal saline). Sixty days after started the treatment, tooth extractions and surgical wounds in soft tissue were performed. Forty-two days after surgeries, rats were euthanized, the specimens were processed and histological analysis performed. At the tooth extraction site, the zoledronic acid group had higher prevalence of Actinomyces than the clodronate and control, whereas at the soft tissue wound, both test groups showed higher values than control. Candida occurrence did not significantly differ between the groups. At the tooth extraction site, single Gram-positive cocci were more prevalent in the zoledronic acid, whereas at the soft tissue wound, they were more prevalent in both test groups than controls. Single Gram-negative cocci did not show any significant difference between the groups at the tooth extraction site; at the soft tissue wound, they were more prevalent in the zoledronic acid group. At the tooth extraction site, bacilli did not differ between the groups, whereas at the soft tissue wound site, they were significantly higher in the test groups. Diplococci, streptococci and staphylococci were rarely found, without significant difference between the groups. Actinomyces was the most prevalent microorganism, followed by single cocci and bacilli. Streptococci, staphylococci, Candida and diplococci do not seem to play a significant role in such lesions whereas the anatomical site seems to be a determinant of the microorganisms involved.