1. Do Copper Jacketed Bullets Auto-Sterilize When Fired? Abstract Several doctors at York Hospital (Hoffer, M. et. al) had noticed a high rate of bacterial infection in the wounds of gunshot patients. Modern ammunition is jacketed in copper, which has intrinsic antibacterial properties. It is also fired at a very high muzzle velocity (approximately 400 m/s), which produces a high temperature. The question asked in this study was, “Does modern ammunition auto- sterilize while being fired?” The two weapons tested were a Glock Model 19 semi- automatic pistol chambered in 9mm Parabellum round, and a Heckler and Koch USP40C semi- automatic pistol chambered in.40 caliber. Three bullet treatments were tested for each weapon; cleaned with 70% isopropyl alcohol, off shelf, and inoculated with Staphylococcus aureus (SA). Cultures were taken before and after each bullet was fired. Bullets were fired into a gelatin trap. Results indicate that bacteria can survive being fired from both weapons. Introduction Three emergency-room doctors at York hospital noticed that gunshot patients had a higher rate of infection than most other injury types (stab wounds, scrapes, etc). The reason for this had never been explained. The only prior studies involving fired copper jacketed bullets investigated the immune response at gunshot sites on canines (Zhang et al. 2001). These studies did not test for bacterial colonies, or how they were brought into the body. One possible reason for the high rate of bacterial infections in gunshot patients includes the transmission of bacteria from the bullet into the body. Since no research on the topic existed, a test would be needed to determine whether or not bacteria could survive a gunshot. Modern ammunition is very often copper jacketed, which has bactericidal properties. Gunshots also produce a significant amount of heat, which is often used to kill bacteria. A study was then proposed, and carried out at York College of Pennsylvania and at the Isaac Walton League firing range. The purpose of this study was to determine if the bacteria could overcome the antibacterial properties that heat and copper possess. Methods Results Discussion The type of bacteria in each trial was determined by morphology and gram reaction. The experimental group of bullets (inoculated with SA) showed that 90% of the traps with bacterial growth specifically had SA as the only type of bacteria in them. Also, the inoculated trials that showed bacteria in barrels after firing all had SA as the only type of bacteria growing (100%). 50% of the inoculated bullets that had bacteria on them after firing had SA as the only type of bacteria. In total, 70% of all inoculated trials that had bacterial growth after firing showed SA as the only form of bacteria growing. All other bacteria present in trials appeared to be normal flora. Using the sign test (Ostle 1963), the trap bacteria % correlated significantly with expected results (p < 0.01). The bullet bacteria % correlated less significantly (p < 0.25). Literature Cited Ostle, B. 1963. Statistics in Research, The Iowa State Press: 466-469 Zhang XH, Pei GX, Wei Kh, Zhou XJ, 2001. Dynamic changes of TNF-alpha content in dogs after gunshot wound in the limbs in hot and humid environment, Di Yi Jun Yi Da Xue Xue Bao, 21: 913-916 Gary Petruzzelli Department of Biological Sciences, York College of Pennsylvania Hypotheses H: Copper jacketing and high firing temperature do not kill bacteria. H o : Copper jacketing and high firing temperature do kill bacteria. The gun barrels and cleaned bullets were cleaned with 70% isopropyl alcohol. The off shelf bullets were taken directly from the bullet box, and the inoculated bullets were inoculated with 15  L of SA before being loaded. Sterile gloves were used in all treatments. Each treatment had five trials per weapon (15 shots for each gun). Shots were fired from a range of 12 feet. Swabbing was standardized, using a predetermined culturing technique for each type of culture. Once fired, the bullet was stopped in a non-bactericidal trap that was designed for this experiment (see figure 2). This trap was housed in PVC piping approximately four inches in diameter, and three feet in length. Inside the pipe, three layers were created. First, sterile sand was poured to a height of two feet inside the pipe. Next, Knox  Gelatin was poured to the top. This created a layer of pure sand, a layer of gelatin/sand mixture, and finally a pure gelatin layer at the top of the trap. The sand end of the trap was sealed with cardboard and tape, the gelatin top was left exposed for bullet entry. The bullet entered the trap and traveled to the sand/gelatin layer, where it stopped. This created a tract in the gelatin layer, which simulated a bullet tract in a gunshot patient. After this tract was swabbed, the trap was emptied and the bullet was collected. Figure 3 Figure 3. Graphs showing the % of trials with bacteria for each treatment and each object cultured (barrel, bullet, or tract). Bullet to tract p < 0.01. Bullet to bullet p < 0.25. Take Home Bacteria can survive a gunshot. Hypothesis is supported. H o is rejected. Future Work Tagged bacteria: - Antibiotic Resistant - GFP or similar marker Different bacteria species: - Spore former - Gram negative Different gun types Indoor firing range Figure 2 Figure 2. Bullet trap diagram showing three layers; sand (A), sand/gelatin (B), and gelatin (C). ABC Bullet Entry Figure 1 12 Figure 1. Pictures of a 9 mm (1) and.40 caliber (2) bullet. Acknowledgments Dr. David Goff Dr. Liam Holtzman Mrs. Barbara Taylor Dr. Bruce Smith Dr. Carolyn Mathur Dr. Karl Kleiner Dr. Michael Hoffer