Aderência bacteriana: estudo in vitro de superfície de aço inoxidável e liga de titânio-alumínio-vanádio de uso ortopédico

Abstract

BASSO, A. C. Bacterial adherence: an in vitro study of stainless steel and titanium-aluminium-vanadium alloy surfaces of orthopedic use. 2009. 102 f. Dissertacao (Mestrado) – Programa de Pos-Graduacao Interunidades em Bioengenharia – EESC/FMRP/IQSC-USP, Sao Carlos, 2009. The utilization of metals in the manufacture of orthopedic implants started in first decades of twentieth century. The increased use of implantable biomaterials increased also infection cases. Biomaterial surface colonization can start at the moment of foreign body insertion in the organism and is usually caused by microorganisms of skin microbiota or adjacent region to the implant. This study aimed to evaluate microbiological methods and scanning electron microscopy (SEM), the bacterial adhesion to surface of stainless steel and titanium alloy of medical use, as well as the surface wetability of these metals. The used bacteria were Staphylococcus epidermidis-ATCC 12228 and Staphylococcus aureus ATCC 25923. The stainless steel (15,0mm diameter x 2,0mm thick) and titanium alloy (12,0mm diameter x 2,0mm thick) discs were inserted, aseptic and individually, into tubes containing 15,0mL Mueller Hinton broth and 200,0 μL of bacterial suspension with 10CFU/mL concentration. Each bacterium was individually studied. The tubes were incubated for 1, 6, 24, 48 and 72 hours under agitation at 37oC. After incubation periods, the discs were removed from culture broth and submitted to the ultrasound bath in 5,0mL of sterile saline. From this liquid were realized dilutions of 10 to 10 to quantify the viable cells. Values were expressed in CFU/mL. S. epidermidis over titanium alloy viable cells number was in 1 hour: 7,20x10; 6 hours: 3,90 x 10; 24 hours: 3,80 x 10; 48 hours: 9,70 x 10 and 72 hours: 1,00 x 10. Over stainless steel viable cells number was in 1 hour: 3,00 x 10; 6 hour: 2,90 x 10; 24 hour: 3,20 x 10; 48 hour: 1,41 x 10 and 72 hour: 1,88 x 10. To S. aureus over titanium alloy viable cells number was in 1 hour: 2,00 x 10; 6 hours: 1,00 x 10; 24 hours: 3,10 x 10; 48 hours: 4,30 x 10 and 72 hours: 5,80 x 10 and over stainless steel viable cells number was in 1 hour: 6,00 x 10; 6 hours: 2,00 x 10; 24 hours: 1,50 x 10; 48 hours: 3,20 x 10 and 72 hours: 6,00 x 10. Both metal surfaces were characterized as medium wetability, where the contact angle of titanium alloy was mean ± standard deviation 39,016 ± 11,267 and stainless steel 58,083 ± 7,165. Both S. aureus as S. epidermidis adhered to surfaces of biomaterials studied, as observed by SEM. Based on the results we concluded that two microorganisms are able to adhere to metal surfaces. This increases the concern about the pathogenesis of infections related to orthopedic implants, since these microorganisms are present in human skin and provide the risk of infection and inflammatory reactions, furthering implant loss to effective cure.