A 49 year old man with stage IIIB colon cancer currently undergoing chemotherapy with 5-fluorouracil and oxaliplatin was referred to the emergency department (ED) for gram negative rod bacteremia. The day prior to admission the patient reported to his infusion center for his 10th cycle of oxaplatin. The patient developed sudden onset rigors shortly after his port was accessed and flushed and had a temperature of 102.5F at that time. He was given acetaminophen and one set of blood culture was obtained from his central line. When his blood culture returned positive for gram negative rods the next day he was told to come to the emergency department.
In the ED his vital signs were all within normal limits and physical exam was unremarkable. He had a port in the left chest wall that did not have any associated erythema, warmth, or tenderness. Laboratory studies were remarkable for leukocytosis (26000/mm3,). His blood culture from the infusion center grew Ralstonia mannitolilytica (resistant to amikacin, cefepime, ceftazidime, gentamicin, meropenem, and tobramycin and sensitive to ceftriaxone, ciprofloxacin, imipenem, levoflocacin, piperacillin/tazobactam, and trimethoprim plus sulfamethoxazole). He was started on piperacillin/tazobactam and was clinically stable during his entire hospitalization. Despite appropriate antibiotics, the patient failed to clear his blood cultures after 72 hours of appropriate antibiotics. His port was removed and subsequent blood cultures were negative. The patient was discharged on ciprofloxacin and completed a 2 week total course of antibiotics with full recovery.
The genus Ralstonia are aerobic Gram-negative, non-fermentative rods that are thought to be of low virulence although recent evidence indicates that Ralstonia may be a more clinically significant pathogen than previously assumed. The genus was established in 1995 and initially contained only one recognized pathogen, Ralstonia picketti (formerly Pseudomonas then Burkholderia, picketti) although a number of species have recently been added including Ralstonia mannitolilytica.
Ralstonia spp has been linked to several outbreaks likely secondary to contamination of high purity water used in the manufacturing of medicinal solutions. The most important means of contamination is likely due to the ability of Ralstonia spp to penetrate the 0.02 μm filters that are used for the sterilization of these solutions. Ralstonia spp has also been shown to form biofilm and both R. picketti and R. mannitoliltyica have been associated with catheter-related bacteremia. The genus has also been linked to pseudo outbreaks due to the contamination of solutions used in laboratory testing. These pseudo outbreaks have led to unnecessary treatment with antibiotics and removal of indwelling devices.
A literature investigation of Ryan et al revealed 86 cases of Ralstonia spp infections (mostly R. Picketti) including severe invasive infections. Similar to the patient in this case, the populations at greatest risk of infection from this genus are immunocompromised patients and patients with indwelling devices.
Hospitalists care for patients with bacteremia frequently. Certain patient populations, such as immunocompromised patients, patients receiving chemotherapy and patients with central lines, are at particular risk of infection with atypical organisms whose pathogenic potential has only recently been recognized.
To cite this abstract:Madut D, Sharma P. Ralstonia: Crossing the Line. Abstract published at Hospital Medicine 2015, March 29-April 1, National Harbor, Md. Abstract 602. Journal of Hospital Medicine. 2015; 10 (suppl 2). https://www.shmabstracts.com/abstract/ralstonia-crossing-the-line/. Accessed December 7, 2019.