Evaluation of Bacterial Contamination of Equine Cadaver Skin Following Injections Using Different Needle Types and Skin Preparation Methods

To assess bacterial translocation through needle punctures and the impact of preparation protocols using equine cadaver skin and different needle sizes and types. Nonprepared, disinfected, clipped and disinfected, and clipped and antiseptically washed skin specimens were sampled sterilely using swabs and biopsies to compare disinfection efficacy. The skin specimens were punctured using 18G hollow needles (18G), 18G needles with stylet (18GM), and 22G hollow needles (22G) and were flushed with sterile saline solution. The saline was collected in blood culture systems or homogenization test tubes and processed for qualitative (ql) or semiquantitative microbiologic evaluation. Disinfection and antiseptic preparation of skin specimens led to a significant reduction of bacteria (P < .05) sampled with swabs and biopsies, whereas clipping did not produce further significant differences. Bacteria were detected in many needle punctures, depending on the preparation protocols and needle types and sizes used. The highest amount of bacteria was detected with 18GM and the lowest with 22G (ql; nonprepared; nonsignificant). Disinfection and antiseptic preparation reduced bacterial translocation significantly in 18G punctures (ql; P < .05), whereas clipping did not result in any further significant difference. Overall, more bacteria were detected after 18G needle punctures when samples were processed qualitatively. Disinfection before injections reduces the number of bacteria translocated into deeper tissue. Larger needles and needles with stylet increase the number of bacteria translocated through the skin.