Pseudo-Outbreak of “Mycobacterium paraffinicum” Infection and/or Colonization in a Tertiary Care Medical Center

Abstract

Objective.To investigate a pseudo-outbreak of “Mycobacterium paraffinicum” (unofficial taxon) infection and/or colonization, using isolates recovered from clinical and environmental specimens.Design.Outbreak investigation.Setting.University-affiliated, tertiary-care hospital.Methods.M. paraffinicum, a slow-growing, nontuberculous species of mycobacteria, was recovered from 21 patients and an ice machine on a single patient care unit over a 2.5-year period. The clinical, epidemiological, and environmental investigation of this pseudo-outbreak is described.Results.Twenty-one patients with pulmonary symptoms and possible risk factors for tuberculosis were admitted to inpatient rooms that provided airborne isolation conditions in 2 adjacent hospital buildings. In addition, 1 outpatient had induced sputum cultured for mycobacteria in the pulmonary function laboratory. Of the samples obtained from these 21 patients, 26 isolates from respiratory samples and 1 isolate from a stool sample were identified asM. paraffinicum. Environmental isolates obtained from an ice machine in the patient care unit where the majority of the patients were admitted were also identified asM. paraffinicum.Conclusions.An epidemiological investigation that used molecular tools confirmed the suspicion of a pseudo-outbreak ofM. paraffinicuminfection and/or colonization. The hospital water system was identified as the source of contamination.