Análise microbiológica in vitro da dispersão de doxiciclina impregnada a membranas absorvíveis utilizadas nos procedimentos regenerativos periodontais e implantares

Abstract

The aim of this study was to evaluate, by means of microbiological in vitro analyses, the capacity and the inhibition period of bacterial growth of the resorbable membranes of bovine bone doxycycline loaded and to compare them with the tetracycline hydrochloride loaded ones. Three variations of the resorbable membrane of bovine bone from the Biochemist laboratory of USPBauru were tested: conventional (C), tetracycline loaded (T) and doxycycline loaded (D). Microbiological analyses based in tests of in vitro sensibility to antimicrobials were made. Aerobic bacteria (Escherichia coli and Staphylococcus aureus) and a pool of nonaerobic bacteria were sown in plates with appropriate media cultures proceeding from the material collected into periodontal pockets. Each plate was divided in four regions and 3 standardized samples of the membranes were deposited, keeping an area without sample to confirm the bacterial growth. It was used a conventional membrane (C) to verify if it presented antimicrobial properties and in the other two regions it was placed (D) and (T) samples. Three plates (1, 2 and 3) were made for each bacterial group, being the doxycycline and tetracycline hydrochloride fragments called (C1/D1/T1; C2/D2/T2; C3/D3/T3) respectively. The aerobic plates were kept into a greenhouse at 35 °C and the nonaerobic ones were kept into a specific anaerobic storage jar. Weekly analyses exchanging the fragments for new plates were made and the capacity of the membranes in inhibiting the evaluated bacterial growth from the formation of inhibition halos around of each sample, which had its diameters surveyed with a digital caliper. The halos presence and the integrity of the samples determined the time of the experiment. The results showed that in all plates of the three bacterial groups, where the samples of (C) were present, did not occur an inhibition of the bacterial growth, thus presenting no halo. In the areas where the membrane was placed (D), as for the E.coli and S.aureus culture, it was observed inhibition halos up to 35 days. It was observed inhibition halos in the membrane (T) areas up to 28 days, except for E.coli (14 days). For both membranes (D) and (T), the maximum inhibition period for the anaerobic pool was 21 days, except for sample (D) present in plate 2, where the halo was present at the 28th day.