Ralstonia mannitolilytica sepsis in neonatal intensive care unit – Be(a)ware of the multidrug resistant nosocomial bug

To the editor,

We read with interest the recent article by Chaturvedi et al. ¹ on the infections and sensitivity pattern of the organisms in an intensive care unit. We would like to share our recent experience in managing outbreak of Ralstonia mannitolilytica sepsis in our neonatal intensive care unit with four neonates deteriorating over a span of five days. This has been rarely reported in the literature till now.^2–4 Ralstonia species are Gram-negative bacilli found in soil, water and plants and can thrive in low-nutrient conditions in various types of hospital water supplies leading to outbreaks. ⁵

We had six babies in level III of our neonatal intensive care unit during the outbreak. Four suffered secondary clinical deterioration due to R. mannitolilytica sepsis. Their median gestational age was 27 (27–38) weeks and their birth weight was 990 (750–2800) g. The median age at clinical deterioration was 8 (4–12) days of life. Three were extremely low birth weight babies requiring non-invasive respiratory support. These three had respiratory distress syndrome at admission and received surfactant for the same. Umbilical lines were removed a week before their deterioration. The term baby who developed R. mannitolilytica sepsis was admitted for meconium aspiration syndrome and was on minimal oxygen support. The preterm babies had secondary clinical deterioration in the form of recurrent apnea requiring intubation and the term baby had decreased activity with mottling. All four babies had thrombocytopenia with counts ranging from 60–130 × 10⁹/m³. C-reactive protein was grossly elevated in all; smears from blood culture broth revealed Gram-negative bacilli. Non-haemolytic grey white colonies were seen in blood agar culture plate and non-lactose fermenting dry colonies in MacConkey’s agar plate (Figure 1). These colonies were oxidase positive. Growth was identified as R. mannitolytica using the matrix-assisted laser desorption/ionisation-time-of-flight mass spectrometer: MALDI-TOF (Vitek MS, Biomerieux) and automated antibiotic susceptibility testing with Minimum inhibitory concentration was performed (ITEK2, Biomerieux). OPEN IN VIEWER

Sensitivity of R. mannitolilytica is shown in Table 1. The first three cases were started on meropenem or piperacillin-tazobactam and amikacin while awaiting culture report. However, the fourth baby was started with co-trimoxazole even before culture report owing to the similar pattern of clinical deterioration. Cerebrospinal fluid analysis was found to be normal in all babies. Tap water, water and swabs from water purifiers, hand rub, liquid soap, dextrose solutions, sterile water, parenteral lipids and amino-acids were sent for culture, but R. mannitolilytica was not isolated. All the neonates were subsequently treated with co-trimoxazole for 10 days and all recovered.

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Table 1.

Sensitivity pattern of Ralstonia mannitolilytica.

Sensitive to	MIC	Intermediate sensitivity to	MIC
Cefepime	≤1	Ceftazidime	16
Ciprofloxacin	≤0.25	Imipenem	8
Levofloxacin	≤0.12	Resistant to	MIC
Minocycline	≤1	Amikacin	≥64
Tigecycline	≤0.5	Gentamicin	≥16
Co- trimoxazole	≤20	Meropenem	≥16
Cefoperazone/Sulbactam	≤8	Piperacillin/Tazobactam	≥128

Quinolones though effective, are known to have short-term reversible musculoskeletal side effects, QT prolongation, hepatotoxicity and dysglycemia in neonates. ⁶ We opted for co-trimoxazole because of our previous experience.^2,4 R. mannitolilytica has been isolated from vapour transfer cartridges of Vapotherm machines, ² but we were unable to trace its source. There were no positive cases after these four neonates.

In summary, Ralstonia spp. are emerging opportunistic multidrug resistant organisms known to have a favourable outcome when treated with appropriate antibiotics. Even after all efforts to identify contaminated source responsible for outbreak, it may not be possible to identify the source of this organism.