Summary: This article is a systematic review and meta-analysis that aims to establish the pooled rate of unexpected intraoperative positive culture (UIPC) in presumed aseptic revision spine surgery. The authors conducted a literature search and identified 12 relevant studies that met the inclusion criteria. They assessed the quality of the included studies using the Agency for Healthcare Research and Quality (AHRQ) tool and evaluated publication bias using a funnel plot and Egger's regression test.
The primary findings of the review are as follows:
Pooled Rate of UIPC: The pooled rate of UIPC in presumed aseptic revision spine surgery was found to be 24.3% in adult patients.
Microbiological Profile: The most commonly isolated organisms were Propionibacterium acnes (C. acnes) and coagulase-negative Staphylococcus species (CNS). C. acnes accounted for 45.4% of positive cultures, followed by CNS at 38.4%.
Prevalence in Pediatric Patients: The prevalence of UIPC was higher in pediatric patients compared to adults (43.2% vs. 24%). C. acnes was more frequently isolated in pediatric patients than in adults (57.73% vs. 42.52%).
Culture Techniques: Studies using both sonication and conventional wound culture reported a pooled UIPC rate of 28.9%. Studies using sonication alone reported a pooled rate of 23.6%, while those using conventional wound culture alone reported a rate of 15.5%.
Risk Factors: Male patients and longer fusion constructs were associated with a higher incidence of UIPC. However, there were no significant differences between the UIPC and non-UIPC groups regarding BMI, smoking history, diabetes mellitus, time from index surgery, number of previous surgeries, and preoperative C-reactive protein (CRP) level.
Treatment and Recommendations: Antibiotic treatment for 4-6 weeks was the most common approach in the included studies. However, there were no clear recommendations on how to treat UIPC or whether it led to surgical site infection (SSI).
Based on these findings, the authors conclude that UIPC is common in presumed aseptic revision spine surgery, and C. acnes is the most commonly isolated organism. They suggest that further research is needed to determine the clinical implications of UIPC and develop standardized treatment protocols.
GRADE Level 2-3
Risk of Bias: The quality assessment of the included studies indicates that some of them were of moderate and low quality.
Inconsistency: The authors mention significant heterogeneity between the studies, which could downgrade the level of evidence. However, sensitivity analyses showed that the results were stable and not dependent on a single study.
Indirectness: The included studies directly addressed the research question.
Imprecision: The precision of the results is limited by the small number of studies and variability in the reported rates of UIPC.
Publication Bias: There's some evidence of publication bias according to the funnel plot, which can also downgrade the level of evidence. However, the authors note that the size effect remained stable, and no imputed studies were found when applying the Duvall trim method.