Open Fractures: Are We Still Treating the Same Types of Infections?

Background: To analyze the rate of methicillin-resistant Staphylococcus aureus (MRSA), gram-negative, and polymicrobial infections in open fractures, measure the efficacy of the current open fracture antibiotic regimen against these infections, identify the most effective agent(s) to cover these infections, and analyze risk factors for infection. Methods: We examined retrospectively 451 patients with open fractures from January 2008 to December 2012 who were treated at our facility. Positive cultures during surgical debridement after wound closure defined an infection. Infecting organisms and their antibiotic sensitivities were identified through microbiology culture reports. Rates of MRSA, gram-negative, and polymicrobial infections were determined. The efficacy of the current regimen (cefazolin and gentamicin) was calculated against gram-positive and gram-negative organisms. Efficacy profiles against infectious organisms were calculated for all commonly tested antibiotics. Patient factors, injury characteristics, and treatment options were analyzed to determine risk factors for infection. Results: Ninety patients (20%) were identified as infected at surgical debridement. Of those 90, 21 (23.3%) were diagnosed with MRSA, 56 (62.2%) were found to have a gram-negative infection, and 46 (51.1%) had polymicrobial infections. Cephalosporins and ß-lactam agents had a 59.2% efficacy rate against gram-positive bacteria and gentamicin showed a 94% sensitivity rate against gram-negative bacteria. Vancomycin (95.8% sensitivity) demonstrated the highest sensitivity for all gram-positive organisms. Amikacin (98.8% sensitivity), meropenem (96.3% sensitivity), and gentamicin (94.2% sensitivity) demonstrated excellent efficacy for all gram-negative organisms. Immuno-compromised status and Gustilo-Anderson type were the only independently predictive risk factors for infection in a multivariable model. Conclusions: Based on this analysis, the rate of MRSA, gram-negative, and polymicrobial infections in open fractures is high and increasing compared with historical cohorts. With the sensitivity of early generation cephalosporins being relatively poor against gram-positive organisms, the present antibiotic regimen for open, long-bone fractures may need to be reconsidered with these emerging trends.