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 nu cleotomy or microsurgery, in a private hospital. Contaminated tap water, us ed for rinsing surgical devices after disinfection, was identified as the s ource of the outbreak. Several cases were recorded in the 4 years after imp lementation of effective control measures because of the long time between discectomy and case detection. The national health authorities decided to l aunch a retrospective investigation in patients who were exposed to M xenop i contamination in that hospital. Methods Mailing and media campaigns were undertaken concurrently to trace e xposed patients for spinal infections. Patients we re screened by magnetic resonance imaging (MRI), and the scans were reviewed by a radiologist who w as 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 i nfection 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 year s). Multivariate analysis showed that the risk of M xenopi spinal infection was related to nucleotomy and high number of patients per operating sessio n. Interpretation Failures in hygiene practices could result in an uncontrolle d outbreak of nosocomial infection. Patients who have been exposed to an ia trogenic infectious hazard should be screened promptly and receive effectiv e information.