Mycobacterium xenopi and Drinking Water Biofilms

Abstract

The ability of Mycobacterium xenopi to colonize an experimental drinking water distribution system (a Propella reactor) was investigated. M. xenopi was present in the biofilm within an hour following its introduction. After 9 weeks, it was always present in the outlet water (1 to 10 CFU 100 ml ؊1 ) and inside the biofilm (10 2 to 10 3 CFU cm ؊2 ). Biofilms may be considered reservoirs for the survival of M. xenopi.Mycobacteria have no usual adherence factors such as pili, fimbriae, and slime, but the hydrophobic properties of the cell wall appear to contribute to the adherence process. The glycopeptidolipids present in the outermost layer of the cell walls of mycobacteria play an important role in surface colonization and biofilm formation (3,7,10). The biofilms represent an important risk of contamination for water distribution systems (8,9,12,13). Lately, a nosocomial outbreak of vertebral osteomyelitis due to Mycobacterium xenopi (5) has been reported by a French surgical center (2). These infections were associated with invasive medical procedures and related to the presence of M. xenopi in the tap water distribution network. However, the role of M. xenopi in the biofilm formation process has not yet been investigated. The aim of this study was to evaluate the ability of M. xenopi to colonize an experimental water supply system.A model biofilm reactor, the Propella reactor (with a distribution pipe 90 mm in diameter and 500 mm long), was used to simulate a drinking water distribution system (1). The inner surface of the pipe was covered with high-density polyethylene (HDPE), which is commonly used in drinking water pipes. The reactor had a volume of 2,080 ml and an HDPE pipe surface of 1,413 cm 2 . It was continuously supplied with tap water (from a local drinking water network) at a flow rate of 83.5 ml h Ϫ1 . The water velocity (0.2 m s Ϫ1 ) was controlled with a marine propeller, which pulsed the water through an inner pipe, giving a flux parallel to the pipe wall. The formation of a biofilm on the pipe wall and the concentration of embedded bacterial cells could be studied by using 20 coupons (1.7 cm 2 ) inserted into the inner surface of the pipe. A special device allowed the removal of the coupons without any flow interruption.M. xenopi (CIP 104035) was subcultured on LowensteinJensen medium at 40°C (optimal growth temperature). A suspension was prepared in sterile distilled water and centrifuged (4,300 ϫ g for 30 min at 20°C). The pellet was washed twice in sterile distilled water to limit carbon contamination from culture media and suspended in sterile distilled water. The suspension was calibrated to a density equivalent to a McFarland standard of 1 and serially diluted (10 Ϫ1 to 10 Ϫ9 ) in sterile distilled water; for the enumeration of mycobacteria, 0.2 ml of each dilution was plated on Lowenstein-Jensen medium (catalog no. 55246; Bio-Rad). Media were incubated at 40°C. Five weeks later, the colonies were counted.The investigation was performed in duplicate with two similar Propella reactors (A an...

From source to filter: changes in bacterial community composition during potable water treatment

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Mycobacterium xenopiClinical Relevance and Determinants, the Netherlands

“…Its survival in fl owing water systems and resistance to common disinfectants enables M. xenopi to contaminate laboratory samples and medical devices such as bronchoscopes, thus causing healthcare-acquired (pseudo) infections and laboratory cross-contaminations (3,6,8,9). Differentiating true infection from pseudoinfection is of paramount importance because treatment of M. xenopi infections is time-consuming and often complicated.…”

Interactions of Cryptosporidium parvum , Giardia lamblia , Vaccinal Poliovirus Type 1, and Bacteriophages φX174 and MS2 with a Drinking Water Biofilm and a Wastewater Biofilm

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