Biofilm Removal Efficacy after Manual and Automated Cleaning of Cardiac Catheters

Background: The removal of biofilm is a challenge when reprocessing cardiac catheters.

Objective: To compare the efficacy of manual and automated cleaning methods using two enzymatic detergents.

Methods: Experimental study involving 36 cardiac catheters that were inoculated with Artifical Soil Test contaminated with 10⁶CFU/ml of P. aeruginosa, E. faecalis e C. albicans during two hours. Each catheter was connected in a line with trypticase soy broth (560ml) during 22h inside and incubator at 35^oC.   The enzymatic detergents were diluted with sterile water at 45^oC for the detergent 1 and room temperature for the detergent 2.In the manual cleaning catheter was immersed in the detergent for 5 minutes when the solution was flush with a 10ml syringe. Sterile gauze was used to dry external surface. The rinsing was performed with sterile water by immersion for 5 minutes using the same technique. They were dried using three air flushes of a syringe. The automated cleaning was performed using a pump with lines connected to the catheters by luer-lock under 2Kgf pressure during 5 minutes. The rinsing was performed with sterile water during 5 minutes and dried with compressed air during 5 minutes and wipped off the external surface with gauze. One cut (1cm) of the medial and distal part of the catheter were collected to perform a microbial load counts in trypticase soy agar plate and incubated at 35^oC for 48 hours. Others cuts of the same region were collected to perform scanning electron microscopy. The fragments was fixed by placing them into 5% glutaraldehyde in cacodylate buffer (0.067M, pH 6.2). Then dehydrated in a graded series of ethanol (30, 50, 70, 90 and 100%) for 10 min each at room temperature and immersed in hexamethyldisilazane overnight at room temperature. The specimens were  mounted on aluminum stubs with silver paint, sputter coated with 25-nm gold particles, and examined with a Zeiss-DSM 950. Positive and negative controls were performed.

Results: After manual cleaning with detergent 1, was detected 5,8 UFC log₁₀/cm² and after automated process 0,8 UFC log₁₀/cm² of P.aeruginosa. Related the same bacteria with the detergent 2, was detected 6,8 UFC log₁₀/cm²  and 1,8 UFC log₁₀/cm² , respectively. After manual cleaning with detergent 1, was detected 2,6 UFC log₁₀/cm² and after automated process 0,4 UFC log₁₀/cm² of S.faecalis. Related the same bacteria with the detergent 2, was detected 6,5 UFC log₁₀/cm²  and 1,4 UFC log₁₀/cm² , respectively. It was not recovered C. albicans in both processes. The electron microscopy showed similar results.

Conclusions: The detergent 1 seems better and the automated process too.