EBQ:Antibiotic prophylaxis for mammalian bites

Under Review Journal Club Article

Medeiros I., Saconato H.. "Antibiotic prophylaxis for mammalian bites". Cochrane Database Syst Rev. 2001. 2(CD001738):.
PubMed Full text PDF

Clinical Question

Is the use of prophylactic antibiotics for mammalian bites effective in preventing wound infections?

Conclusion

Antibiotic prophylaxis after human bites and bites of the hand may decrease the risk of wound infection but further evidence is needed. No evidence shows effectiveness in the use of antibiotic prophylaxis after cat or dog bites.

Major Points

• Prophylactic antibiotics were associated with statistically significant reduction of infection rate for the following type of bites:
  • bites by humans
  • bites located on the hand (NNT=4)
• Prophylactic antibiotics did not appear to reduce rate of infection after bites by cats or dogs
• Wound type (e.g. lac vs puncture) did not influence effectiveness of prophylactic antibiotics
• Prevention of tetanus/rabies, together with adequate cleansing of the wounds are the cornerstone of infection prevention in mammalian bites. In select patients, with concerning bite location (e.g. hand) and type of mammal (e.g. human) prophylactic antibiotics may be beneficial

Study Design

• Systematic review of randomized and quasi-randomized controlled trials
• Studies were reviewed by two reviewers
• 8 studies included

Population

Patient Demographics

• Two studies included only children
• Two studies included only adults
• Three studies included both children and adults

Inclusion Criteria

• RCT's included which studied patient's with mammalian bites
  • Compared abx vs. placebo OR no intervention
  • Ability to determine infection at bite site
• Patients who present for medical care within 24 hours of bite AND no signs of infection

Exclusion Criteria

• The studies excluded patients whose bites violated the joint capsule or tendon

Interventions

• Of the studies included, patients were randomized to either antibiotics vs. placebo OR no intervention
• Large antibiotic heterogeneity across the trials:
  • Phenoxymethyl penicillin (2 trials)
  • Oxacillin (2 trials)
  • Dicloxacillin (2 trials)
  • Co-trimoxazole (1 study)
  • Cephalexin OR Erythromycin (1 study)
  • Ceclor, Kefzol or Pen G (1 study)

Outcomes

Primary Outcome

• When looking at all mammalian bites, prophylactic antibiotics did not significantly reduce the rates of infection (OR 0.49, 95% CI 0.15 to 1.58)

Subgroup analysis

Animal Species

• Human bites:
  • Infection rate was significantly reduced in antibiotic group 0% (0/33) vs. the control group 47% (7/15)
  • (OR 0.02, 95% CI 0.00 to 0.33)
• Dog Bites:
  • No statistically significant reduction of infection rate
  • 4% (10/225) for antibiotic group vs to 5.5% (13/238) for control
• Cat Bites:
  • Only 1 study with 11 patients
  • Higher infection rate reported in the control group 67% (4/6) vs treatment group 0% (0/5)

Wound Type

Wound type did not significantly influence the effect of prophylactic antibiotics

• Punctures: 7% (1/14) vs 31% (5/16)
• Lacerations: 3% (2/63) vs 6% (4/66)
• Avulsions: 5% (2/41) vs 3% (1/30)

Location of Wound

Significant reduction of infection rate was seen in hand bites

• Hand: 2% in antibiotic group vs 28% in control (OR 0.10, NNT=4)
• Trunk: Infection occurred in only 1 patient in control group, none in antibiotic group
• Head/Neck: Infection occurred in only 1 patient in control group, none in antibiotic group
• Arms: No infection recorded in either group

Funding

Funding for Cochrane Review's come from internal sources within the Cochrane Collaboration, primarily from proceeds from The Cochrane Library.