An Outbreak of Ralstonia mannitolilytica Septicaemia at a Tertiary Care Hospital: An Observational Cross-sectional Study

Abstract

Introduction: Ralstonia spp. is an emerging non fermenting Gram negative bacillus implicated in cases of bloodstream infections in immunocompromised individuals. It is commonly found as an environmental contaminant in hospital settings. Several sporadic outbreaks have been reported from different parts of the world due to Ralstonia spp. This study reports a similar outbreak at a tertiary care hospital in Northern India. Aim: To determine the source of Ralstonia septicaemia in affected patients at a tertiary care centre. Materials and Methods: The present observational crosssectional study was conducted at the Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences (SGPGIMS), Lucknow, Uttar Pradesh, India from February 2020 until the end of March 2020 (two months). A total of 2,650 blood cultures were received during the study period; of these, 53 (2%) patients were found to have Ralstonia mannitolilytica infection over a two month period. All patients from various wards whose blood cultures showed growth of Ralstonia species were included in this study. The organism was identified using both biochemical tests and Matrix-Assisted Laser Desorption Ionisation-Time of Flight Mass Spectrometry (MALDI-TOF MS). Antibiotic sensitivity testing was conducted using the Kirby-Bauer disk diffusion assay. Environmental surveillance was conducted to detect the source of origin. Patients’ age, sex, duration of hospital stay, co-morbidities, and other clinical parameters were recorded. Statistical analysis was performed using Microsoft Excel. Results: There were 52 cases of septicaemia due to Ralstonia mannitolilytica, and one Ralstonia isolate was obtained from intraoperative pus. Most of the Ralstonia isolates obtained were Multidrug-Resistant (MDR), showing resistance to imipenem, meropenem, amikacin, aztreonam, and sensitivity to first-line drugs such as ceftazidime, piperacillin-tazobactam, cefoperazone-sulbactam, levofloxacin, and trimethoprimsulfamethoxazole, resulting in successful treatment. Out of 53 cases, one patient succumbed to death due to surgical complications. Environmental sampling did not yield any organisms resembling Ralstonia spp. Conclusion: The environmental source of the Ralstonia bacteraemia outbreak could not be identified in this study. All patients except one were successfully treated with antibiotics. Clinicians and microbiologists should remain vigilant in case any such case arises to prevent further outbreaks.