Mycobacterium xenopi spinal infections after discovertebral surgery: Investigation and screening of a large outbreak

Background: Mycobacterium xenopi spinal infections were diagnosed in 1993 in patients who had undergone surgical microdiscectomy for disc hernia, by nucleotomy or microsurgery, in a private hospital. Contaminated tap water, used for rinsing surgical devices after disinfection, was identified as the source of the outbreak. Several cases were recorded in the 4 years after implementation of effective control measures because of the long time between discectomy and case detection. The national health authorities decided to launch a retrospective investigation in patients who were exposed to M xenopi contamination in that hospital. Methods: Mailing and media campaigns were undertaken concurrently to trace exposed patients for spinal infections. Patients were screened by magnetic resonance imaging (MRI), and the scans were reviewed by a radiologist who was unaware of the diagnosis. Suspected cases had discovertebral biopsy for histopathological and bacteriological examination. Findings: Of 3244 exposed patients, 2971 (92%) were informed about the risk of infection and 2454 (76%) had MRI. Overall, 58 cases of M xenopi spinal infection were identified (overall cumulative frequency 1.8%), including 26 by the campaign (mean delay in detection 5.2 years, SD 2.4, range 1-10 years). Multivariate analysis showed that the risk of M xenopi spinal infection was related to nucleotomy and high number of patients per operating session. Interpretation: Failures in hygiene practices could result in an uncontrolled outbreak of nosocomial infection. Patients who have been exposed to an iatrogenic infectious hazard should be screened promptly and receive effective information.