Distribution of Bacterial Contamination in Partial Penetration Surrogate Ballistic Wounds

With the rise in use of IEDs during armed conflicts, there has been an increase in the number of injuries to the extremities. Shrapnel and debris ejected during the explosion become high-speed projectiles capable of penetrating soft tissues, bringing bacterial contamination into the wound. If not properly treated, that contamination could lead to infection. Studies aimed at understanding the distribution of bacterial contamination along the permanent cavity could provide useful information to improve treatment protocols for these types of injuries. In this paper, a lower extremity surrogate model was used to investigate bacterial distribution in partial penetration ballistic wounds. The targets used were ballistic gelatin blocks that had an Escherichia coli-laden filter paper placed on their front face. Spherical projectiles were fired into the targets adjusting their speed to obtain three different partial penetration depths. After each shot, a gelatin strip containing the permanent cavity was extracted and segmented. The permanent cavity was removed from each segment, placed in a test tube with buffer solution, and heated in a water bath to melt the gelatin. Standard microbiology protocols were followed to determine the number of colony forming units (CFUs) in each segment. The bacteria distribution was represented by percent of total CFU in the permanent cavity versus segment number. In addition, bacterial contamination as a function of projectile penetration depth was explored. For the cases considered, most of the bacterial contamination occurred in the segments closer to the projectile entry point.

Influence of distance to depth shot of a CO2-powered airsoft gun with lead shot ammunition and shape of the temporary and permanent cavity in ballistic gelatine.

The increasing aggression in the population, which is undoubtedly associated with the onset of narcissism, also entails an increase in the number of assaults in society. Of course, the number of clashes when a Weapon is used is also increasing. In most cases, these are weapons classified as weapons of category D (according to the Czech legislation), especially air guns, expansion weapons, and airsoft guns. This fact needs to be addressed, not by impulsive bans under duress, but by subjecting these weapons to the investigation, especially in the field of wounding ballistics, which answers the questions about the wounding potential of these weapons. This paper deals with one of these weapons, specifically airsoft gun with used ammunition lead shot. The depth of the shot and the size of the temporary and permanent cavity in relation to the distance were investigated, the contact distance was measured, and then the distance of 5 m.

Influence of rib impact on thoracic gunshot trauma

IntroductionThe influence of rib impact on thoracic gunshot trauma remains unclear, despite its high occurrence. This study therefore investigates the effect of rib impact on a bullet’s terminal properties and injury severity.MethodsTwo bullets were used: 5.56×45 mm (full charge and reduced charge) and 7.62×51 mm (full charge). For each bullet, three impact groups were tested: (1) plain 10% ballistic gelatin (control) conditioned at 4°C, (2) intercostal impact, and (3) rib impact, the latter two tested with samples of porcine thoracic walls embedded in gelatin. Analysis included penetration depth, trajectory change, yaw, fragmentation, velocity reduction, energy deposition and temporary and permanent cavity characteristics.ResultsNo significant differences were observed for most variables. Differences were found between rib (and intercostal) impact and the control groups, suggesting that the inclusion of thoracic walls produces an effect more significant than the anatomical impact site. Effects were ammunition specific. For the 7.62×51 mm round, rib impact caused an earlier onset of yaw and more superficial permanent gelatin damage compared with plain gelatin. This round also formed a larger temporary cavity on rib impact than intercostal impact. Rib (and intercostal impact) created a smaller temporary cavity than the control for the 5.56×45 mm round. For the reduced-charge 5.56×45 mm round, rib and intercostal impact produced greater velocity reduction compared with plain gelatin.ConclusionsThis study provides new insights into the role of rib impact in thoracic gunshot injuries, and indicates that the effects are ammunition dependent. Unlike the 5.56×45 mm rounds, rib impact with the 7.62×51 mm rounds increases the risk of severe wounding.

Distribution of Bacteria in Simplified Surrogate Extremities Shot With Small Caliber Projectiles

Experiments were conducted to determine bacteria distribution trends in wound cavities of simplified surrogate extremities shot using small caliber projectiles. Two different shapes of targets, cylindrical and square, were used in this study. Cylindrical targets are more representative of an extremity but create difficulties while conducting tests due to inconsistent cavity lengths and optical distortions. Square targets, which are not as susceptible to the problems mentioned above, could be used in place of cylindrical ones if their shape does not significantly affect the distribution of bacteria within the wound cavity. Surface contamination of the targets in the experiments was represented using a circular piece of filter paper moistened with a solution with a known amount of Escherichia coli strain K-12. The projectiles used were 11.43-mm (0.45-in) caliber round nose projectiles shot from a commercially available air rifle. The permanent cavities were extracted from the targets and sliced into small, evenly spaced segments and the area surrounding the permanent cavities was removed with a biopsy punch. The radial tears that were made by the formation of the temporary cavity and surround the permanent cavity were removed using a scalpel. The permanent cavity and radial tears for each section were processed and plated on agar plates. Commercial software was used to count the number of colony forming units on each plate and the percentage of the total bacterial colony count per segment was determined. High speed video and motion analysis software was used to qualitatively and quantitatively compare the temporary cavities in the cylindrical and square targets. The data from the experiments showed that the bacteria distribution trends for the cylindrical and square targets were similar even though the maximum openings of the temporary cavity at the entrance and exit locations were higher for the cylindrical ones. For both target shapes, the bacterium was evenly distributed between the permanent cavity and the radial tears in the middle sections of the “wound tracks.” In addition, significantly higher amounts of bacterium were found in the entrance and exit segments compared with the rest of the segments in the “wound tracks”.

Effect of Projectile Caliber and Speed on Bacterial Distribution in a Leg Surrogate

This paper examines the relationship between ballistic factors and bacterial distribution along a surrogate wound channel using ballistic gelatin cylinders with dimensions representative of the calf region of an average human leg. The ballistics factors considered were projectile caliber and speed, and Escherichia coli (E. coli) was used as the representative bacteria. In order to reduce the possibility of contamination by outside bacteria, the E. coli first underwent a transformation protocol to express Green Fluorescent Protein (GFP) and become resistant to the antibiotic ampicillin. A set volume of bacteria was pipetted onto a small piece of filter paper which was placed on the surface of a ballistic gelatin cylinder and a projectile was shot through the bacteria saturated filter paper. The ‘wound track’ was divided into slices, and the area surrounding the permanent cavity was removed with a biopsy punch, liquefied, and grown on selective LB media containing ampicillin. Examination of the bacterial colony count along the permanent cavity segments allowed comparison of how variations in projectile caliber and speed affected contamination distribution along the ‘wound track’. Initial results indicate that larger calibers may result in higher contamination distribution at the projectile entrance and exit regions and higher speeds compress the distribution and result in a drop in contamination level near the exit.