Monitoring for Methylobacteria in Water Systems

Methylobacteria are slow-growing, pink-pigmented organisms that have been reported to be opportunistic pathogens in immunocompromised patients (3, 7, 8, 9). Methylobacterium mesophilicum and Methylobacterium zatmanii have been the two most commonly reported species isolated in clinical samples. Tap water has been implicated as a possible mode of transmission for these bacteria in the hospital environment. Methylobacteria have been reported to exhibit resistance to chlorination (6) and have been isolated from tap water in various clinical settings, including an investigation of a pseudo-outbreak (4), water from dental units (2), and blood bank purification units (11). The association of these organisms with tap water recently prompted Hornei et al. (7) to suggest that it may be helpful to monitor for these organisms in water distribution systems in hospital units for immunocompromised patients.