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Effect of Intrawound Vancomycin Powder on the Pathogen Spectrum and Antimicrobial Susceptibility of Postoperative
Lukas F Panzenboeck1, Damian L Duerrschnabel1, Jennyfer A Mitterer2
1Department of Spine Surgery, Orthopaedic Hospital Speising, Vienna, Austria.
Study Design:
Secondary microbiological analysis of a patient-blinded, single-center randomized controlled trial.
Objective:
To determine whether intrawound vancomycin powder alters the surgical site infection (SSI) pathogen spectrum and gram-status distribution, selects for vancomycin- or methicillin-resistant organisms, or affects the rate of non-wound infections after elective posterior lumbar interbody fusion.
Summary Of Background Data:
Intrawound vancomycin powder is widely used to prevent SSI after lumbar fusion, but retrospective data raise concerns about a gram-negative pathogen shift and resistance selection; randomized evidence is limited.
Methods:
Adults undergoing elective posterior lumbar interbody fusion were enrolled between August 2015 and April 2019. Of 308 randomized, 292 were analyzed (Control, n=152; Vancomycin, n=140). All received intravenous cefuroxime; Vancomycin patients additionally received 1 g vancomycin powder before closure. We assessed the SSI pathogen spectrum and gram-status distribution, vancomycin and methicillin susceptibility, and non-wound infection rates. Wound cultures were tested to EUCAST breakpoints; Fisher's exact test with Wilson 95% CIs was used.
Results:
Gram-positive organisms dominated both groups (7 of 8 [88%] vs. 3 of 3 [100%]) with no gram-negative shift; isolates included Cutibacterium acnes (n=4), MSSA, MRSE (n=2 each), S. saccharolyticus, E. cloacae, plus one polymicrobial case. Vancomycin susceptibility was preserved in 9 of 9 (100%); no VRE, VRSA, or MRSA occurred; both MRSE isolates were Control. Non-SSI events were equivalent (8 of 152 [5.3%] vs. 6 of 140 [4.3%]; P=0.788), dominated by urinary-tract pathogens.
Conclusions:
Intrawound vancomycin powder did not alter the gram-positive-dominated SSI spectrum, did not select for vancomycin- or methicillin-resistant organisms, and had no systemic effect on non-wound infections. These randomized data support empiric regimens retaining gram-positive coverage when SSI is suspected after lumbar fusion.
Level Of Evidence:
Level of Evidence: 1b.
Insights
Intrawound vancomycin powder did not change the types of bacteria causing surgical site infections (SSIs) after lumbar fusion. This randomized trial found no increase in resistant organisms or non-wound infections.
Area of Science:
- Spinal surgery
- Infectious disease
- Microbiology
Background:
- Intrawound vancomycin powder is frequently used to prevent surgical site infections (SSIs) after lumbar fusion.
- Concerns exist regarding a potential shift towards gram-negative pathogens and resistance selection, but robust randomized evidence is limited.
Purpose of the Study:
- To investigate the impact of intrawound vancomycin powder on SSI pathogen spectrum and resistance.
- To assess effects on gram-status distribution and non-wound infections following elective posterior lumbar interbody fusion.
Main Methods:
- A patient-blinded, single-center randomized controlled trial involving 292 adults undergoing elective posterior lumbar interbody fusion.
- Patients received either cefuroxime alone (Control) or cefuroxime plus 1g vancomycin powder (Vancomycin) before wound closure.
- Analysis included SSI pathogen spectrum, gram-status, vancomycin/methicillin susceptibility, and non-wound infection rates.
Main Results:
- Gram-positive organisms predominated in both groups, with no shift to gram-negative pathogens observed.
- All tested isolates remained susceptible to vancomycin; no vancomycin- or methicillin-resistant organisms (VRE, VRSA, MRSA) were detected.
- The rate of non-SSI events was similar between groups (5.3% vs. 4.3%), primarily involving urinary tract pathogens.
Conclusions:
- Intrawound vancomycin powder did not alter the SSI pathogen profile or select for resistant organisms in this study.
- No significant systemic effect on non-wound infections was observed.
- These findings support current empiric treatment guidelines for suspected SSIs after lumbar fusion, emphasizing gram-positive coverage.
