Importância do controle de micro-organismos no processo de produção de próteses de valvas cardíacas de origem biológica

Abstract

Prosthetic heart valves are used to surgery replace heart valves which have an abnormality or problem that prevents its normal operation. The bioprosthetic heart valve preserved in low concentration glutaraldehyde solutions first appeared in 1974 and since then its use is growing. With the increased use of prosthetic valves, the number of reported infections related to these devices also increased. In these cases, the main isolated microorganisms are Staphylococcus spp., Streptococcus spp., Gram-negative bacteria, including Pseudomonas spp. and fungi. However, in recent years, the number of cases of infective endocarditis caused by mycobacteria in patients with bioprosthetic heart valve has increased. Despite the major sources of prosthetic heart valves contamination continues to be inoculation of microorganisms from the skin microbial flora or adjacent region during surgery; pathogen inoculation by the hands of the medical staff members or instrumental and pathogens dissemination through hematogenous via, recent reports alert to the possibility of patient contamination with the material used to manufacture the bioprosthetic heart valve. To elaborate this monograph, we follow the process of bioprosthetic heart valve production in a manufacturer to evaluate the presence of microorganisms in steps that involve the production of these devices, the identification and tests to verify the susceptibility of microorganisms in 0.2% glutaraldehyde solution and 10% formaldehyde, used during the process. We found that 84.3% of a total of 51 pre sterilization samples tested showed growth of microorganisms and 100% of the microorganisms isolated were rapidly growing mycobacterium M. chelonae / M. abscessus. It was observed that as greater the processing time of the prosthetic heart valves, greater were the microbial load and the resistance of the isolated microorganisms to 0.2% glutaraldehyde solution. Mycobacterium isolated from prosthetic heart valves, which were less time in processing (up to 08 days) also showed sensitivity to lower concentration of glutaraldehyde (0.1%). No microorganism isolated was resistant to the treatment with 10% formaldehyde solution, the final step of the assembly process. Thus, it is necessary that manufacturers of bioprosthetic heart valves assess the tissue microbial load along its assembly lines, as well as their procedures for screening and sterilization since mycobacteria contamination is characterized by slow growth and difficulty of detection.