Prophylactic antibiotics in patients with skin wounds

The term prophylactic antibiotics implies the use of such antibiotics as a preventive measure in the absence of an established infection. Although virtually all traumatic wounds can be considered contaminated with bacteria to some extent, only a small percentage eventually become infected. Accordingly, it is possible that only a subset of high-risk wounds or patients stand to benefit from prophylactic antibiotics. Estimates of the incidence of traumatic wound infection vary widely, depending on the method of study and the population examined, but most studies have found an incidence of 4.5% to 6.3%. In a meta-analysis of seven studies, the wound infection rates in the control populations ranged from 1.1% to 12% with a mean of 6%.

When considering the role of antibiotics in preventing wound infection, it is important to consider the risk factors for infection. These factors relate to the nature of the host, the characteristics of the wound, and the treatment used. The host risk factors include extreme young or old age; medical problems, such as diabetes mellitus, chronic renal failure, obesity, malnutrition, and immunocompromising illnesses; and such therapies as corticosteroids and chemotherapeutic agents. Wound factors that increase risk include high bacterial counts in the wound; oil contamination; and crush injury. Risk of infection also varies according to wound depth, configuration, and size. Wounds associated with tendons, joints, and bones; puncture wounds; intraoral wounds; and most mammalian wounds are also considered at high risk for infection. Certain treatments, such as the use of epinephrine-containing solutions, may also increase the risk of infection. Furthermore, risk of infection increases with the number of sutures. Finally, risk of infection may be higher with an inexperienced treating doctor than with an experienced one.

When antibiotics are used to prevent infections in traumatic wounds, certain indications are often cited. Such indications include wounds associated with open joints or fractures, human or animal bites, and intraoral lacerations. Despite limited evidence, antibiotics also are recommended for heavily contaminated wounds (eg, those involving soil, feces, saliva, vaginal secretions, or other contaminants). Prophylactic antibiotics also are advocated for traumatic wounds in patients who have prosthetic devices and for preventing bacteremia in patients at risk for developing endocarditis. Systemic antibiotics also are recommended when there is a lapse of more than 3 hours since injury, when there is lymphedematous tissue involvement, and when the host is immunocompromised.

According to the principles of presurgical prophylaxis, antibiotics, if they are to be given at all, should be administered as soon as possible after the injury, if possible within the first 3 hours, and continued for 3 to 5 days. The antibiotic therapy should also be directed against the most common skin pathogens, Staphylococcus aureus and Streptococci . Cloxacillin and first-generation cephalosporins are appropriate as first-line therapy.

Despite the frequent use of prophylactic antibiotics to prevent traumatic wound infections, some clinicians still have reservations about the effectiveness of their use. Some investigators argue that most uncomplicated wounds heal without systemic antibiotic therapy. In addition, in many situations, prophylactic antibiotics not only fail to reduce the overall rate of infection, but also may skew the bacteriology toward more unusual or resistant pathogens. In fact, clinical studies fail to demonstrate a lower infection rate among patients with uncomplicated wounds treated with prophylactic antibiotics than among control subjects, and no randomized trials have shown a clear benefit of antibiotic prophylaxis for simple wounds in immunocompetent patients. Furthermore, a meta-analysis of randomized trials found no benefit from the use of prophylactic antibiotics for simple wounds.

Several randomized, controlled studies have examined the ability of antibiotics to prevent infection of simple nonbite wounds managed in the emergency department. A meta-analysis of seven of these studies showed that wound infection rates in the control populations ranged from 1.1% to 12%, with a mean of 6%, with patients treated with antibiotics having a slightly greater risk of infection than untreated controls. More detailed analysis of several subgroups looked at whether or not the wounds were sutured, whether the wounds were located on the hands or elsewhere, what was the route of antibiotic administration (oral vs intramuscular), and what antibiotic type was employed. This analysis also failed to show any benefit for the use of systemic prophylactic antibiotics. In 1995, Cummings and Del Becaro concluded that there was little justification for the routine administration of antibiotics to patients who had simple nonbite wounds managed in the emergency department. However, these investigators were unable to examine the potential benefits of antibiotics in high-risk groups because most of these were excluded from their clinical trials. Accordingly, selection bias remains a problematic issue, with most of the published studies looking at the role of antibiotics in management of traumatic wounds in the emergency department.

Use of prophylactic antibiotics for prevention of infection of intraoral wounds

Intraoral wounds, including tongue lacerations and orocutaneous wounds, are commonly encountered in the emergency department. Such wounds can involve the mucosa only or the mucosa and adjacent skin, so-called “through-and-through” lacerations. These wounds are often the result of penetration of the lips by the patient’s teeth following minor or major trauma or seizures. Most emergency medicine textbooks consider larger mucosal wounds, particularly those that are through-and-through wounds, to be dirty wounds and at high risk for infection because of the oral bacterial flora. These books generally recommend a course of prophylactic antibiotics to prevent infection after these wounds are repaired. Infection has been reported in up to 12% of wounds involving the mucosa only and in up to 33% of through-and-through lacerations Altieri and colleagues studied the benefits of 3 days of penicillin prophylaxis in a randomized, controlled trial of 100 intraoral lacerations managed in a pediatric emergency department. The overall infection rate was found to be 6.4%, with no statistically significant difference between the control (8.5%) and the penicillin (4.4%) groups. Although this study had a limited number of patients enrolled, it concluded that routine antibiotic prophylaxis is unwarranted for simple intraoral lacerations in children, although it may be beneficial in sutured wounds. Steel and colleagues conducted a prospective, randomized, double-blind, controlled study of 5 days of oral penicillin versus placebo therapy in adults. They found a statistically significant difference in the infection rates between compliant patients in the two groups (6.7% for penicillin vs 18.8% in the placebo group). In a subgroup of those patients who had through-and-through lacerations, 7% of the treatment group versus 27% of the control group developed wound infections. These investigators could not conclusively recommend prophylactic penicillin for adults with intraoral lacerations treated within 24 hours after injury. However, the investigators felt that noncompliant patients and those who had through-and-through lacerations may benefit from a course of prophylactic penicillin. Penicillin-allergic patients should receive clindamycin.

Mark and Granquist reviewed the literature on the use of prophylactic oral antibiotics for treatment of intraoral wounds. Only four clinical research articles fulfilled their criteria for inclusion in the review. They concluded that prophylactic oral antibiotics play an inconclusive role in the treatment of intraoral wounds. They also concluded that all published randomized studies to date have failed to demonstrate a statistically significant difference in wound infection rates when antibiotics are compared with placebo or routine wound care. The only placebo-controlled, double-blind, randomized clinical trial evaluating the efficacy of oral prophylactic antibiotic use in simple intraoral wounds had small enrollment numbers and accordingly failed to conclusively demonstrate a statistically significant benefit of such use. Mark and Granquist recommended that until a larger clinical trial is performed, treatment decisions on the use of prophylactic antibiotics for intraoral wounds should be guided by clinical judgment of the practitioner.

The value of antibiotic prophylaxis for lacerations of the tongue is less well studied, although one underpowered study reported no infections in 28 children managed without antibiotics. Accordingly, there is insufficient evidence to make any definitive recommendations with regard to antibiotic prophylaxis for tongue or intraoral lacerations in children.

Use of prophylactic antibiotics for prevention of infection of intraoral wounds

Intraoral wounds, including tongue lacerations and orocutaneous wounds, are commonly encountered in the emergency department. Such wounds can involve the mucosa only or the mucosa and adjacent skin, so-called “through-and-through” lacerations. These wounds are often the result of penetration of the lips by the patient’s teeth following minor or major trauma or seizures. Most emergency medicine textbooks consider larger mucosal wounds, particularly those that are through-and-through wounds, to be dirty wounds and at high risk for infection because of the oral bacterial flora. These books generally recommend a course of prophylactic antibiotics to prevent infection after these wounds are repaired. Infection has been reported in up to 12% of wounds involving the mucosa only and in up to 33% of through-and-through lacerations Altieri and colleagues studied the benefits of 3 days of penicillin prophylaxis in a randomized, controlled trial of 100 intraoral lacerations managed in a pediatric emergency department. The overall infection rate was found to be 6.4%, with no statistically significant difference between the control (8.5%) and the penicillin (4.4%) groups. Although this study had a limited number of patients enrolled, it concluded that routine antibiotic prophylaxis is unwarranted for simple intraoral lacerations in children, although it may be beneficial in sutured wounds. Steel and colleagues conducted a prospective, randomized, double-blind, controlled study of 5 days of oral penicillin versus placebo therapy in adults. They found a statistically significant difference in the infection rates between compliant patients in the two groups (6.7% for penicillin vs 18.8% in the placebo group). In a subgroup of those patients who had through-and-through lacerations, 7% of the treatment group versus 27% of the control group developed wound infections. These investigators could not conclusively recommend prophylactic penicillin for adults with intraoral lacerations treated within 24 hours after injury. However, the investigators felt that noncompliant patients and those who had through-and-through lacerations may benefit from a course of prophylactic penicillin. Penicillin-allergic patients should receive clindamycin.

Mark and Granquist reviewed the literature on the use of prophylactic oral antibiotics for treatment of intraoral wounds. Only four clinical research articles fulfilled their criteria for inclusion in the review. They concluded that prophylactic oral antibiotics play an inconclusive role in the treatment of intraoral wounds. They also concluded that all published randomized studies to date have failed to demonstrate a statistically significant difference in wound infection rates when antibiotics are compared with placebo or routine wound care. The only placebo-controlled, double-blind, randomized clinical trial evaluating the efficacy of oral prophylactic antibiotic use in simple intraoral wounds had small enrollment numbers and accordingly failed to conclusively demonstrate a statistically significant benefit of such use. Mark and Granquist recommended that until a larger clinical trial is performed, treatment decisions on the use of prophylactic antibiotics for intraoral wounds should be guided by clinical judgment of the practitioner.

The value of antibiotic prophylaxis for lacerations of the tongue is less well studied, although one underpowered study reported no infections in 28 children managed without antibiotics. Accordingly, there is insufficient evidence to make any definitive recommendations with regard to antibiotic prophylaxis for tongue or intraoral lacerations in children.

Topical antibiotics for treatment of traumatic wounds

Application of topical antibiotic ointments has often been proposed to help reduce infection rates and prevent scab formation. Ointments containing bacitracin, neomycin, or polymyxin have been routinely used on simple lacerations by many emergency physicians in the United States. Animal studies have shown that topical antimicrobials inside the wound before closure may reduce the infection rate in contaminated wounds. One double-blind, randomized human trial found a 5% infection rate with antibiotic ointment compared with an unexpectedly high 17.6% rate with a petrolatum jelly control. Other studies, however, have found no significant reduction in infection rates with topical antibiotics. Because of the higher risk of infection with crush injuries when compared with sharp lacerations, some experts recommend topical antibiotics only for stellate wounds with abraded skin edges, but this is not based on comparative trial data. So far, the effectiveness of topical antibiotic ointments in managing minor wounds has not been properly investigated. Moreover, despite the frequent use of topical antibiotics, surprisingly few studies have assessed their efficacy after suture wound closure.