The Effect of Under-Dosing Prophylactic Antibiotics in the Care of Open Tibial Fractures.

Abstract

OBJECTIVES:

To determine the frequency and effect of under-dosing prophylactic weight-based antibiotics in patients with open tibial fractures. We hypothesized that patients who did not receive appropriate weight-based dosing of prophylactic antibiotics would have higher rates of infection.

DESIGN:

Retrospective cohort study.

SETTING:

Level 1 Trauma Center.

PATIENTS/PARTICIPANTS:

Patients 18 years of age or older with high-grade (Gustilo-Anderson type IIIA or IIIB) open extraarticular tibial fractures over a 5-year period.

MAIN OUTCOME:

The primary outcome was deep infection within one year of initial injury. Appropriate weight-based dosing of cefazolin was defined as: at least 1 g for patients <80 kg, 2 g for patients between 80 and 120 kg, and 3 g for patients >120 kg.

RESULTS:

Sixty-three patients met the inclusion criteria; 21 (33%) were under-dosed with cefazolin at the time of initial presentation. Among the 20 patients who subsequently developed deep infection, only 55% were appropriately dosed with cefazolin; of the patients who did not develop deep infection, 72% were appropriately dosed with cefazolin (P = 0.18). Univariate analysis revealed that hypertension was associated with infection (P = 0.049). Multivariable logistic regression analysis of infection due to all organisms did not reveal a statistically significant reduction in the odds of infection with appropriate weight-based dosing of cefazolin [Odds ratio = 0.42 (95% confidence interval, 0.12-1.48), P = 0.177]. Five of 7 (71%) of the gram positive, non-methicillin-resistant Staphylococcus aureus, infections occurred in patients who were under-dosed with cefazolin. Five (23.8%) of 21 patients who were under-dosed with cefazolin had gram-positive, non-methicillin-resistant S. aureus infections, compared to 2 (4.8%) of 42 patients who were appropriately dosed (P = 0.036).

CONCLUSIONS:

Under-dosing of weight-based antibiotics in the treatment of open fractures is common. Appropriate weight-based dosing of cefazolin for prophylaxis in high-grade open tibial fractures reduces the frequency of infection due to cefazolin-sensitive organisms. Interestingly, organisms not susceptible to cefazolin were responsible for the majority of infections. The effect of under-dosing of cefazolin and other weight-based antibiotics deserves further investigation in larger studies.

LEVEL OF EVIDENCE:

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

• Authors: Catherine R Olinger, David Christopher Carver, Vikki G Nolan, John C Weinlein
• Journal: Journal of orthopaedic trauma (J Orthop Trauma) Vol. 32 Issue 7 Pg. 322-326 (07 2018) ISSN: 1531-2291 [Electronic] United States
• PMID: 29634602 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Cefazolin

Topics

• Adolescent
• Adult
• Aged
• Antibiotic Prophylaxis
• Cefazolin (administration & dosage)
• Cohort Studies
• Dose-Response Relationship, Drug
• Female
• Fracture Fixation, Internal (adverse effects, methods)
• Fractures, Open (diagnostic imaging, therapy)
• Humans
• Injury Severity Score
• Logistic Models
• Male
• Middle Aged
• Reference Values
• Retrospective Studies
• Surgical Wound Infection (epidemiology, prevention & control)
• Tibial Fractures (diagnostic imaging, drug therapy, surgery)
• Trauma Centers
• Treatment Outcome
• Young Adult