Bacterial contamination rate and associated factors during bone and tendon allograft procurement from Spanish donors: exploring the contamination patterns.

Background: Allograft contamination during extraction represents a major limiting factor for tissue bank availability. Contamination rates remain persistently high independent of the hospital, country or year considered.

Aim: To analyse the factors associated with contamination of bone and tendon samples extracted from Spanish donors.

Methods: Data for 1162 bone and tendon samples extracted from 102 donors between 2014 and 2017 were collected retrospectively from the hospital database. Descriptive statistics, potentially associated factors and correlation of contamination between samples extracted from different anatomical locations of the same donor were analysed.

Findings: In total, 227 (19.54%) of the extracted samples [131 (18.49%) bone samples and 96 (20.92%) tendon samples] rendered positive cultures and were discarded. Male sex [odds ratio (OR) 2.023; P=0.019], extraction of >10 samples per donor (OR 1.997; P<0.001) and extraction time >240 min (OR 1.755; P=0.001) were factors independently associated with a higher contamination rate. Meanwhile, the tissue sample type 'bone-patellar tendon-bone' was associated with a significantly lower contamination rate (OR 0.446; P=0.001). Significant correlation between certain localization of contaminated samples and the concordance of bacterial species was also observed.

Conclusion: Factors related to the extraction procedure, such as total extraction time, extraction sequence, number of samples extracted and anatomical location of extracted samples, play a major role in allograft contamination. Further optimization of procedures, guided by the contamination patterns analysed in this study, should help to increase tissue bank availability.