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Antibiotic Therapy in Gunshot Wound Injuries

Simpson, Bonnie, M.; Wilson, Robert, H.; Grant, Richard, E.

Clinical Orthopaedics and Related Research: March 2003 - Volume 408 - Issue - p 82-85
SECTION I SYMPOSIUM: Current Concepts and Principles of Gunshot Musculoskeletal Injuries
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Protocols for antibiotic prophylaxis in the treatment of fractures caused by gunshots have not been delineated clearly in the literature to date. The current review of the literature reveals that antibiotic therapy for treatment of these fractures is predicated on the muzzle velocity of the weapon used to inflict the fracture. General consensus has been reached regarding the requirement of at least 24 hours of intravenous antibiotic treatment in fractures caused by high-velocity weapons in conjunction with the appropriate wound and fracture care. Similarly, in fractures caused by shotguns, thorough wound debridement and 24- to 48-hour administration of intravenous antibiotics is necessary. However, in fractures caused by low-velocity weapons, there is not a preponderance of the evidence showing that there is a distinct advantage to using antibiotic prophylaxis in these injuries. Special clinical consideration must be given regarding the use of antibiotics in fractures caused by gunshots that are intraarticular and those about the hand, foot, and ankle.

From the Division of Orthopaedic Surgery, Howard University Hospital, Washington, DC.

Reprint requests to Bonnie M. Simpson, MD, 1160 Varnum Street, NE Suite 104, Washington, DC 20017. Phone: 202-269-7383; Fax: 202-269-7319; E-mail rgrantwa@aol.com.

DOI: 10.1097/01.blo.0000053167.71678.cf

Although gunshot injuries are defined by the rapid entry of an unsterile missile into a region of the body, the literature does not provide consistent guidelines on the use of antibiotics in the treatment of fractures caused by gunshots. The literature does not clearly show that there is a definite risk of infection after fractures caused by low-velocity gunshots. There also is no universal antibiotic treatment protocol for the treatment of fractures caused by gunshots. The severity of gunshot injuries is highly variable rendering the identification of a specific pathogen or development of a universal protocol difficult. The lack of consensus regarding the use of antibiotics in the treatment of fractures caused by gunshots will be addressed. In addition, recommendations based on the types of gunshot injuries will be proposed.

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Background

An important consideration in the treatment of fractures caused by gunshots is the decision to categorize all such injuries as open fractures. In reference to low-velocity injuries, earlier theories reported that the missile tract of a low-velocity missile is sterilized by the thermocapacity of the bullet at the time of firing. 8,13 However, Thoresby and Darlow 14 documented the contamination of wounds from bacteria and foreign bodies that were drawn into the wound by the temporary cavitation or vacuum effect caused by low-velocity bullet as it passed through tissues. Bacteriologic counts must reach 105 to 106 organisms per gram of tissue or per milliliter of fluid to classify as an infection. Tian et al, 15 in a canine study, showed that immediately after injury by a low-velocity missile, cultured bacteriologic counts were approximately 102. Cultures of the missile tracks at 12 and 24 hours after injury showed counts 1.1 × 105 and 4.8 × 105, respectively, showing that the critical level of bacteria is reached in missile tracks of lowvelocity gunshot wounds within 24 hours of injury. None of the specimens were treated with antibiotics before or after wounding.

Fractures caused by gunshot injuries are caused by multiple types of firearms that can be classified as low-velocity, high-velocity, or shotguns. 6,8,13 Missiles with a muzzle velocity less than 2000 feet per second generally are defined as low-velocity, and those with a muzzle velocity greater than 2000 feet per second are classified as high-velocity. 13 Shotgun blasts have muzzle velocities that often are greater than 2000 feet per second. However, shotgun injuries often are classified separately because of the variable composite ammunition.

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Low-Velocity Gunshot Injuries

Controversy exists about the use of antibiotics in patients with injuries caused by low-velocity gunshots. Prior recommendations concerning the antibiotic prophylaxis of low-velocity injuries range from the use intravenous antibiotics for several days to no antibiotic use. In 1974, Patzakis et al 12 recommended the use of antibiotics in patients with low-velocity gunshot injuries. This was a prospective, randomized study of 78 fractures. More recently, Knapp et al 9 reported a 2% infection rate in patients with fractures caused by low-velocity gunshots that were treated with either intravenous cephapirin and gentamicin or with oral ciprofloxacin. They concluded that patients with fractures caused by low-velocity gunshots that involved extraarticular long bones, except those of the distal tibia, can be treated effectively with oral antibiotics. Similarly, Hollman and Horowitz 7 found no perioperative infections and no cases of osteomyelitis in a retrospective study of 19 patients with femoral fractures caused by low-velocity missile injuries who were treated for 48 hours with a first generation cephalosporin. Geissler et al 4 reported no statistically significant difference in the incidence of infection between the two groups of patients with low-velocity gunshot injuries, one of which received one intramuscular dose of cefonicid, a first-generation cephalosporin, and the other was treated with a 48-hour course of intravenous antibiotics. These authors reported that the cost of treatment in the former group was substantially lower.

Several authors have recommended against the routine use of intravenous or oral antibiotics in the treatment of patients with fractures caused by low-velocity gunshots. For example, Howland and Ritchey, 8 based on a retrospective review of 72 patients with fractures caused by low-velocity gunshots who were treated operatively and nonoperatively, did not recommend the routine use of antibiotics, provided that wound debridement had been satisfactory and that the injured extremity was immobilized. Those authors documented two infections in 42 patients. In a retrospective review, Marcus et al 11 reported similar infection rates in patients with injuries caused by low-velocity gunshots who did and did not receive antibiotics; the infection rates were 4.2% and 3.8%, respectively, regardless of whether the patient had surgery. This study also showed that the more serious infections occurred in patients who had been treated with antibiotics, leading the authors to conclude that routine antibiotics were not necessary for patients with wounds that were not grossly contaminated and patients who could be immobilized properly. Similarly, in a randomized, prospective study of patients with fractures caused by low-velocity gunshots, all of whom were treated nonoperatively, Dickey et al 2 reported no statistically significant difference in the infection rates between the 36 patients treated with 24 hours of intravenous cefazolin and the 37 patients who received no antibiotics. Two infections developed in patients in this study; both patients had low-velocity gunshot fractures about the ankle. One patient had been treated with intravenous antibiotics, and the other patient did not receive antibiotic treatment.

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High-Velocity Gunshot and Shotgun Injuries

Injuries caused by high-velocity missiles, greater than 2000 feet per second, have notoriously high rates of infection. 8,12 The standard recommendations for treatment of such injuries include wide and thorough wound debridement with the removal of foreign material, fracture stabilization, and administration of 48 to 72 hours of intravenous antibiotics. 6 Benzyl penicillin was the antibiotic of choice during the wartime era. 6,13 It continues to be useful because of its effectiveness against clostridia and beta-hemolytic streptococci. However, with the emergence of penicillin-resistant bacteria, cephalosporin prophylaxis has been recommended in the treatment of injuries caused by high-velocity gunshots. 1

Patzakis et al 12 reported infections in four of 78 patients with fractures caused by gunshots. Three of the four infections were in patients with fractures caused by high-velocity gunshots. The remaining infection was in a patient who had a fracture caused by a lowvelocity gunshot indicating that the speed of the missile is pivotal in predicting the possibility of infection. These authors also found a statistically significant decrease in the rates of infection in patients with open fractures treated with cephalothin versus patients treated with penicillin and streptomycin.

Of particular importance is the environment in which many high-velocity gunshot injuries occur. The use of rifles and shotguns in rural or wooded areas must alert the physician to the possibility of gross contamination with fecal material. These situations require broader antibiotic coverage, namely a third-generation cephalosporin, an aminoglycoside and penicillin, as recommended for treatment of Grade III open fractures in the Gustilo and Anderson 5 classification.

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Special Circumstances

Information regarding antibiotic treatment of intraarticular gunshot injuries has been reported sparsely. It is agreed that the removal of bullet fragments is appropriate treatment to avoid lead poisoning. 13 Ganocy and Lindsey 3 devised a treatment protocol for low-velocity intraarticular fractures in which the decision whether to use antibiotics was based on the extent of wound contamination. For patients with skin or material contamination, they recommended 24 to 48 hours of prophylactic antibiotics. Long et al 10 recommended as many as 72 hours of intravenous cefazolin and gentamicin for patients sustaining intraarticular hip fractures. They recommended that patients with grossly contaminated wounds, including those with bowel communication or with grossly dirty skin or clothing, should receive 1 to 2 weeks of broad-spectrum antibiotics. Also, the location of the gunshot injury deserves special attention. Several studies have shown that there is a slightly higher rate of rate of infection in gunshot injuries to the hands and feet than in injuries to other anatomic locations. 4 Patients sustaining fractures caused by low-velocity gunshots about the ankle have shown an increased propensity to have an infection develop. 2,9 The relatively poor soft tissue envelope, muscle coverage, and limited blood supply are possible reasons for higher rates of infection about the hand, foot, and ankle.

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Recommendations

Based on the current review of the literature, antibiotic prophylaxis in high-velocity, shotgun, and intraarticular gunshot fractures is recommended. The recommendation for treatment of high-velocity gunshot injuries is intravenous administration of at least 48 hours of a first-generation cephalosporin. Gentamicin should be added in cases of soft tissue defects or cavitary lesions. Patients with shotgun injuries may be treated likewise. Penicillin must be added in patients with gross contamination. As for fractures caused by low-velocity gunshots, the literature shows no distinct advantage in administering prophylactic antibiotics. Therefore, antibiotic prophylaxis in injuries caused by low-velocity gunshots is not clearly recommended although proper wound care and fracture treatment are essential to achieving a satisfactory result. Additional prospective studies are required to conclusively establish the guidelines for the possible use of antibiotics in the treatment of low velocity gunshot injuries.

There are exceptions to the current recommendations. Patients with intraarticular injuries and injuries sustained in specific locations require antibiotic prophylaxis regardless of missile velocity. Patients with intraarticular gunshot injuries require a minimum of 24 to 48 hours of intravenous of antibiotic prophylaxis; as many as 72 hours are needed for patients with contaminated wounds. First-generation cephalosporin, with or without gentamicin, is the antibiotic of choice. It is recommended that at least 24 hours of intravenous antibiotic prophylaxis with a third-generation cephalosporin be administered to patients with low-velocity gunshot fractures about the ankle.

The administration of tetanus prophylaxis is mandatory in all patients who sustain gunshot injuries. Patients who have received a tetanus booster within the past 5 years should receive 0.5 mL of tetanus toxoid. Those patients who have not had a tetanus booster within 5 years, or patients who have an unknown immunization history, should receive 0.5 mL of tetanus toxoid and 250 units of tetanus immunoglobulin.

Universally accepted protocols for antibiotic prophylaxis in fractures caused by gunshots do not exist. Therapeutic recommendations for high-velocity gunshot wounds and shotgun injuries have approached consensus by requiring surgical debridement and intravenous antibiotics. Patients with low-velocity injuries may require superficial debridement and appropriate fracture treatment, but mandatory antibiotics are not clearly necessary. Contrastingly, patients with grossly contaminated and intraarticular gunshot injuries require intravenous antibiotic coverage. Careful clinical judgment is required in treatment of gunshot injuries involving areas such as the hand, foot, and distal tibia. Intuitively, antibiotic prophylaxis is recommended in these patients.

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References

1. Bowyer GW, Rossiter ND: Management of gunshot wounds of the limbs. J Bone Joint Surg 79B:1031–1036, 1997.
2. Dickey RL, Barnes BC, Kearns RJ, Tullos HS: Efficacy of antibiotics in low-velocity gunshot fractures. J Orthop Trauma 3:6–10, 1989.
3. Ganocy K, Lindsey RW: The management of civilian intra-articular gunshot wounds: Treatment considerations and proposal of a classification system. Injury 29(Suppl 1):SA1–SA6, 1998.
4. Geissler WB, Teasdall RD, Tomasin JD, Et al: Management of low-velocity gunshot-induced fractures. J Orthop Trauma 4:39–41, 1990.
5. Gustilo R, Anderson J: Prevention of infection in the treatment of one thousand twenty-five open fractures of long bones. J Bone Joint Surg 58A:453–458, 1976.
6. Hennessey MJ, Banks HH, Leach RB, Quigley TB: Extremity gunshot wound and gunshot fracture in civilian practice. Clin Orthop 114:296–303, 1976.
7. Hollmann M, Horowitz M: Femoral fractures secondary to low-velocity missiles: Treatment with delayed intramedullary fixation. J Orthop Trauma 4:64–69, 1990.
8. Howland WS, Ritchey SJ: Gunshot fractures in civilian practice. J Bone Joint Surg 53A:47–55, 1971.
9. Knapp TP, Patzakis MJ, Lee J: Comparison of intravenous and oral antibiotic therapy in the treatment of low-velocity gunshots: A prospective randomized study of infection rates. J Bone Joint Surg 78A:1167–1171, 1996.
10. Long WT, Brien EW, Boucree JB, Et al: Management of civilian gunshot injuries to the hip. Orthop Clin North Am 26:123–131, 1995.
11. Marcus NA, Blair WF, Shuck JM, Omer GE: Low-velocity gunshot wounds to the extremities. J Trauma 12:1061–1064, 1980.
12. Patzakis MJ, Harvey JP, Ivler D: The role of antibiotics in the management of open fractures. J Bone Joint Surg 56A:532–541, 1974.
13. Russotti GM, Sim FH: Missile wounds of the extremities: A current concepts review. Orthopedics 8:1106–1116, 1985.
14. Thoresby FP, Darlow HM: The mechanisms of primary infection of bullet wounds. Br J Surg 54:359–61, 1967.
15. Tian HH, Deng GG, Huang MJ, Et al: Quantitative bacteriological study of the wound track. J Trauma 28(Suppl):S215–S216, 1988.

Section Description

Richard E. Grant, MD; and Bonnie M. Simpson, MD—Guest Editors

© 2003 Lippincott Williams & Wilkins, Inc.