Abstract

Background

Bites by mammals are a common problem and they account for up to 1% of all visits to hospital emergency rooms. Dog and cat bites are the most common and people are usually bitten by their own pets or by an animal known to them. School‐age children make up almost a half of those bitten. Prevention of tetanus, rabies and wound infection are the priorities for staff in emergency rooms. The use of antibiotics may be useful to reduce the risk of developing a wound infection.

Objectives

To determine if the use of prophylactic antibiotics in mammalian bites is effective in preventing bite wound infection.

Search methods

Relevant RCTs were identified by electronic searches of MEDLINE, EMBASE, LILACS and the Cochrane Controlled Trials Register databases in November 2000.

Selection criteria

We included randomised controlled trials which studied patients with bites from all mammals. Comparisons were made between antibiotics and placebo or no intervention. The outcome of interest was the number of infections at the site of bite.

Data collection and analysis

Two reviewers extracted the data independently. All analyses were performed according to the intention‐to‐treat method.

Main results

Eight studies were included. The use of prophylactic antibiotics was associated with a statistically significant reduction in the rate of infection after bites by humans. Prophylactic antibiotics did not appear to reduce the rate of infection after bites by cats or dogs. Wound type, e.g. laceration or puncture, did not appear to influence the effectiveness of the prophylactic antibiotic. Prophylactic antibiotics were associated with a statistically significant reduction in the rate of infection in hand bites (OR 0.10, 95% CI 0.01 to 0.86; NNT = 4, 95% CI 2 to 50).

Authors' conclusions

There is evidence from one trial that prophylactic antibiotics reduces the risk of infection after human bites but confirmatory research is required. There is no evidence that the use of prophylactic antibiotics is effective for cat or dog bites. There is evidence that the use of antibiotic prophylactic after bites of the hand reduces infection but confirmatory research is required.

Author(s)

Iara Marques Medeiros, Humberto Saconato

Abstract

Plain language summary

Antibiotics for reducing the rate of infection after bites by mammals such as humans

Bite wounds may become infected due to the transfer of bacteria from the mouth of mammals into the skin. There was a decrease in the risk of developing an infection after a human bite when given antibiotics. Antibiotics also decreased the chance of developing a wound infection after a bite on the hand. Further studies are required to confirm these findings.

Author(s)

Iara Marques Medeiros, Humberto Saconato

Reviewer's Conclusions

Authors' conclusions 

Implications for practice 

There is insufficient evidence that the use of prophylactic antibiotic is effective for dog bites, because most of the studies included were methodologically deficient and had small sample sizes. There is evidence that the use of antibiotic prophylactic after bites of the hand reduces infection. Weak evidence suggests that antibiotic prophylaxis after bites by humans reduces infection.

Implications for research 

New randomised controlled trials of good quality are necessary to evaluate the effectiveness of prophylactic antibiotics after mammalian bites. Future randomised controlled trials should address the following aspects:

• OBJECTIVES:

1. Evaluate the effectiveness of antibiotic prophylaxis for mammalian bites to prevent wound infection. 
 2. To establish possible predictors of infection risk, such species of animal aggressor, location and severity of wound, age, previous morbidity of victims (diabetes mellitus, immunodeficiency disorders, peripheral vascular diseases).

• INCLUSION CRITERIA: Adults and children with mammalian‐bite wounds who present to an emergency room within 24 hours of injury.
• EXCLUSION CRITERIA: superficial abrasions, clinical signs of infection, those having other medical problems requiring antibiotic treatment or allergies to antibiotic.
• TYPES OF INTERVENTION: The choice of antibiotics should be based on the flora of the oral cavity of mammalian aggressors (sensitivity obtained by swabbing the wound).
• OUTCOME MEASURES:

1. Incidence of infection, analysed and presented according to location and type of wound. Infection criteria described by Talan (Talan 1999) could be used. Wound should be considered infected if meets one of three major criteria:

• fever
• abscess
• lymphangitis.

Alternatively ‐ they could be considered infected if they show four of five minor criteria:

• wound associated with erythema that extends more than 3 cm from the edge of the wound
• tenderness at the wound site
• swelling at the site
• purulent drainage
• a peripheral white‐cell count of more than 12,000 per cubic millimeter.

2. Incidence of adverse events

Get full text at The Cochrane Library