Hemodialysis International 2019 CASE REPORT Outbreak of nonfermentative Gram-negative bacteria (Ralstonia pickettii and Stenotrophomonas maltophilia) in a hemodialysis center May K. THET, 1 Ma. Lourdes F. PELOBELLO, 1 Milton DAS, 1 Mohammed M. ALHAJI, 2 Vui Heng CHONG, 3 Muhammad Abdul Mabood KHALIL, 1 Terence CHINNIAH 4 , Jackson TAN 2 1 Department of Renal Medicine, RIPAS Hospital, Bandar Seri Begawan, Brunei Darussalam; 2 PAPRSB Institute of Health Sciences, Universiti Brunei Darussalam, Brunei Darussalam; 3 Department of Medicine, RIPAS Hospital, Bandar Seri Begawan, Brunei Darussalam; 4 Department of Microbiology, RIPAS Hospital, Bandar Seri Begawan, Brunei Darussalam Abstract 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 vas- cular 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 iso- lates in routine microbiological specimens from dialysis centers, especially if there is a senescent water treatment system and a practice of reprocessing dialysers. Keywords: Outbreak, hemodialysis, Ralstonia Pickettii, Stenotrophomonas maltophilia INTRODUCTION Nonfermentative Gram-negative bacteria (NFGNB) is an emerging and threatening problem in hospitals. It is reported to be present in up to 5% of water sources in hos- pital wards and more than half the isolates showed anti- biotic resistance. 1 Most are opportunistic pathogens that cause infections in debilitated and immunosuppressed hos- pital patients. Previous reports have focused on Pseudomo- nas spp. and Acinetobacter spp. because of their higher isolation rates in microbiological specimens. 2 Rarer bacteria like Ralstonia pickettii and Stenotrophomonas maltophilia have recently generated greater interests because of their flourish- ing prevalence and difficult resistant profiles. Nosocomial Correspondence to: M. A. M. Khalil, Department of Renal Medicine, RIPAS Hospital, Bandar Seri Begawan BA1710, Brunei Darussalam. E-mail: doctorkhalil1975@hotmail.com Conflict of Interest : All authors have declared no competing interest. Disclosure of grants or other funding: None. © 2019 International Society for Hemodialysis DOI:10.1111/hdi.12722 1