How long should we keep clinical isolates involved in bone and joint infections in microbiology laboratories?

Bone and joint infections (BJI), particularly periprosthetic joint infections (PJI), remain major postoperative complications. Although international guidelines have clarified diagnostic criteria, recommendations on clinical strain preservation remain scarce. Microbiology laboratories routinely store isolates from severe infections, but protocols and storage duration vary widely. This narrative review synthesizes international and national guidelines (ICM, EBJIS, IDSA, SPILF), French regulatory texts, and published data on bacterial preservation techniques. Methods of conservation (serial subculture, preservation media, freezing at various temperatures, desiccation, and lyophilization) and their impact on strain viability and genetic stability were examined. Most guidelines recommend preserving strains involved in BJI or infective endocarditis for molecular comparison, follow-up, or medico-legal purposes, yet few specify concrete duration or storage conditions. French SPILF guidelines require at least one year at - 80 °C. Preservation methods differ in cost, practicality, and long-term genetic integrity, with - 80 °C-- 130 °C offering optimal stability. Inadequate storage conditions-temperature fluctuations, humidity, oxygen exposure-may lead to contamination, DNA degradation, or genetic drift. Given the clinical, epidemiological, and medico-legal value of archived isolates, long-term standardized storage in dedicated biobanks is essential. A minimum five-year preservation period appears both feasible and beneficial to strengthen diagnostic reliability, outbreak investigations, and future research.