Non-tuberculous mycobacteria and homeaquariums

Abstract

Aquarium water is generally recycled and filtered but rarely treated or renewed; this stagnation in a medium rich in organic compounds makes it a significant potential reservoir of micro-organisms. We investigated the potential airborne dispersion of mycobacterium strains into a home aquarium's immediate environment, by taking air samples using a Sartorius® membrane biocollector (Figure 1): next to the aquarium, first closed (A1 and A2), then open (A3 and A4); simulating fish feeding; and at a distance from the aquarium, before handling the aquarium filter (A5) and while cleaning and changing it (A6). Water samples were taken on the same occasion from the household water supply system (W1, W2, W3) and from the aquarium filter collector (F1 and F2). Samples were then processed using standard mycobacteria isolation methods used in our laboratory for environmental testing, cultures being examined for bacterial growth every day for three months. We found that the water from the public supply system was colonized by Mycobacterium gordonae (sample W1 before the household filter). We did not detect any mycobacteria in several water samples taken beyond this (W2 and W3), but a shower was contaminated with M. gordonae and Mycobacterium fortuitum (W4). Testing for mycobacteria in the aquarium water was positive, with a heavy M. fortuitum growth from the third day. The two air samples taken next to the closed aquarium (A1 and A2) did not yield mycobacteria, but opening the lid (A3 and A4) and handling the filter (A6) produced aerosols contaminated, respectively, by Mycobacterium peregrinum and both M. peregrinum and M. fortuitum.