Bacterial Analysis of Hamstring Autograft With Vancomycin Presoaking in Primary Anterior Cruciate Ligament Reconstruction Shows High Incidence of Colonization Without Early Clinical Infection

Purpose: To determine the incidence of autograft bacterial colonization (BC) in anterior cruciate ligament reconstruction (ACLR) and to identify any bacteria type at the genus level. Methods: This prospective descriptive study included patients aged 18 years or older undergoing ACLR with hamstring autograft. Thirty-one patients (21 male and 10 female patients), with a mean age of 32.2 years, were included, with a mean follow-up period of 150 days (range, 90-208 days). Three samples were taken from every surgical procedure: a sample from the graft at the time it was obtained, a sample from the graft after tibial fixation, and a sample from the saline solution receptacle on the instrument table (control). All grafts underwent vancomycin presoaking. Bacterial composition was determined by next-generation sequencing of the 16S ribosomal RNA coding gene. Descriptive statistics were used to summarize data. The Fisher exact test was used to compare group samples (with P < .05 considered significant). Results: BC was detected in 11 of 31 patients (35.4%). BC was found in the first sample (sample from the graft at the time it was obtained) in 1 patient and in the third sample (control) in another. All 11 patients showed BC in the second sample (sample from the graft after tibial fixation), with statistical significance (P = .003). In these samples with BC, 47 types of gram-negative bacteria (GNB) were identified, averaging 6.8 bacteria per sample, with 3.97% relative abundance per bacterium. Pseudomonas was present in 5 of 11 samples, with 6.76% relative abundance. Additionally, 33 types of gram-positive bacteria (GPB) were found, averaging 6 bacteria per sample, with 9.62% relative abundance per bacterium; Streptococcus was present in 8 of 11 samples, with 26.23% relative abundance. All colonized samples exhibited both GPB and GNB. Conclusions: Bacterial contamination during ACLR is frequent, with the presence of both GNB and GPB. Although such colonization was common, no early clinical infections were noted in our patient cohort. Level of Evidence: Level III, prospective descriptive study.