Outbreak of nonfermentative Gram-negative bacteria (Ralstonia pickettii and Stenotrophomonas maltophilia) in a hemodialysis center.

We report a case series of seven patients with nonfermentative Gram-negative bacteria infections in a single dialysis center; four patients with Ralstonia pickettii and three patients with Stenotrophomonas maltophilia. Two of the seven patients were admitted to hospital for intravenous antibiotic treatment, while the rest were treated with oral antibiotics at home. Both the admitted patients had temporary vascular catheter infections from the aforementioned pathogens. We conclude that the outbreak is due to colonization of treated reverse osmosis water, presumably through contamination via polluted filters and compounded by the usage of reprocessed dialysers in the dialysis center. This is especially relevant because contaminated treated water is directly introduced into the blood compartment of the dialysers during reprocessing. In addition, there seems to be a propensity for both organisms to cause prolonged febrile reactions in patients with temporary vascular catheters, likely through the early development of biofilm. Intensification of general sterilization procedures, servicing and replacement of old decrepit components of the water treatment system and temporary cessation of dialyser reuse practice seem to have halted the outbreak. Due to the virulent nature and difficult resistant profile of nonfermentative Gram-negative bacteria, we strongly recommend meticulous vigilance in the surveillance of culture isolates in routine microbiological specimens from dialysis centers, especially if there is a senescent water treatment system and a practice of reprocessing dialysers.