Abstract
Ralstonia mannitolilytica is a non-fermentative, Gram-negative bacillus increasingly recognized as an opportunistic pathogen in healthcare settings, particularly among immunocompromised individuals. Its resilience in aqueous environments and resistance to standard sterilization methods make it a formidable nosocomial pathogen. This article explains our management of Ralstonia mannitolytica infection in our ICU.
Introduction
Ralstonia mannitolilytica, formerly classified as Pseudomonas mannitolilytica, is an aerobic, Gram-negative bacillus that has emerged as a significant opportunistic pathogen particularly in intensive care units (ICUs)(1). Its ability to thrive in low-nutrient environments, form biofilms, and exhibit resistance to multiple antibiotics and disinfectants makes it a formidable challenge in critical care. It is commonly seen in patients on Hemodialysis(2).
Case report
A 31 years old female, known case of beta thalassemia trait has undergone elective LSCS in outside hospital in outside hospital, and has been referred to our ER with history of abdominal distension and hypotension in POD 1. On arrival in ER she was hemodynamically unstable. USG abdomen revealed hemoperitoneum with drop in Hb. She was taken up for emergency laparotomy. There was a haematoma in uterine adnexa which was removed and hemostasis was achieved. 4 units of PRBC, 4 units of FFP and 4 units of RDP were transfused during surgery. She was shifted to ICU with post operative elective ventilation. She was gradually weaned and extubated on POD 1. She developed new onset fever from POD 3. Cultures were taken and started on meropenam. USG abdomen revealed no free fluid in abdomen. Blood cultures grew ralstonia mannitolytica resistant to meropenam and hence antibiotics were changed to levofloxacin. Her fever spikes started to settle. She improved and she was discharged with oral ciprofloxacin for 7 days.
Discussion
Ralstonia mannitolytica was first reported in 1995, following which few case were reported in oncological, dialysis and post transplant patients(3). Most common sources were water used for dialysis and oxygen delivery systems(4). The critical aspects of Ralstonia Mannitolytica infection including epidemiology, clinical features, diagnostic challenges and treatment complexities will be discussed in this study
Epidemiology
R. mannitolilytica infections are rare but increasingly reported, particularly in immunocompromised or critically ill patients. The pathogen is ubiquitous in environmental sources such as soil, water, and moist surfaces, which facilitates its introduction into healthcare settings. Outbreaks have been linked to contaminated medical solutions, including sterile water, saline, and disinfectants, as well as medical devices like ventilators and catheters(5). The increasing recognition of R. mannitolilytica as a nosocomial pathogen underscores the need for heightened awareness in high-risk settings.
Pathogenesis
R. mannitolilytica’s pathogenicity stems from its ability to form biofilms, which enhance its survival on medical devices and resistance to antimicrobial agents(6). Biofilm formation likely contributed to the persistence of infection in this case, as evidenced by positive repeat blood cultures despite initial antibiotic therapy. The pathogen’s capacity to survive in low-nutrient solutions, such as saline, explains its association with contaminated medical fluids.
Clinical manifestations
R.Mannitolytica can cause sepsis ranging from mild fever to septic shock. Main manifestations include central line associated infections, peritonitis associated with peritoneal dialysis, systemic bacteremia, pneumonia and meningitis(7).
Diagnostic challenges
Accurate identification of R. mannitolilytica poses significant challenges due to its biochemical similarity to other non-fermentative Gram-negative bacilli, such as Pseudomonas aeruginosa, Burkholderia cepacia complex, and Cupriavidus spp. Conventional biochemical tests often misidentify R. mannitolilytica, leading to diagnostic delays(8). In this case, the use of matrix-assisted laser desorption/ionization time-offlight mass spectrometry (MALDI-TOF MS) was pivotal in confirming the diagnosis, highlighting the critical role of advanced diagnostic tools in modern microbiology. Misidentification can lead to inappropriate
antibiotic therapy, exacerbating patient outcomes, particularly in the context of R. mannitolilytica’s variable resistance profile. Clinicians must maintain a high index of suspicion for uncommon pathogens like R. mannitolilytica in ICU patients with persistent or atypical infections
Antimicrobial resistance
R.Mannitolytica shows resistance to different types of antibiotics including gentamycin, tobramycin, colistin, aztreonam & meropenam. Data on mechanism of resistance on β-Lactum antibiotics and carbapenams were still not clearly understood. Presence of OXA βLactamases like OXA-443, OXA-444 have been reported as primary mechanism(9).
Treatment
This resistance profile complicates empirical therapy, as standard regimens for Gram-negative sepsis (e.g., meropenem) may be ineffective. There is no clear treatment guidelines for R.Mannitolytica infections. Most of strains were found to be sensitive to ceftazidime, cefeperazone-sulbactum and fluroquinolones.
Infection control The identification of contaminated saline as the infection source underscores the critical role of environmental reservoirs in R.mannitolilytica outbreaks. The pathogen’s ability to survive in disinfectants and form biofilms on medical equipment necessitates rigorous infection control measures. Routine testing of medical solutions and water systems, as well as regular maintenance of medical devices, can mitigate the risk of outbreaks. Furthermore, healthcare facilities must ensure proper training of staff in infection control practices to minimize the introduction and spread of environmental
pathogens.
Conclusion
This case of R. mannitolilytica bloodstream infection illustrates the multifaceted challenges posed by this emerging pathogen in ICU settings. Its environmental resilience, diagnostic complexity, and antimicrobial resistance necessitate a coordinated approach involving advanced diagnostics, tailored therapy, and stringent infection control
Referances
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Dr. Dhineshraj
DrNB Critical Care Medicine
Kauvery Hospital, Chennai