[Usefulness of MALDI-TOF mass spectrometry in infections by infrequent microorganisms such as Ochrobactrum intermedium]

The first case of Ochrobactrum intermedium bacteremia in a pediatric patient with malignant tumor

BACKGROUND

Ochrobactrum spp. are non-fermenting, Gram-negative bacilli that are regarded as emerging human pathogens of low virulence that can cause infections. The first identified case of Ochrobactrum intermedium was reported in 1998 in a liver transplantation patient with liver abcess. There are no reports of infections in pediatric patients. Here, we report the first case of O. intermedium bacteremia in a pediatric patient.

CASE PRESENTATION

A two and a half years old male was admitted with fever, chills and nausea. He had been diagnosed as pineoblastoma and underwent surgical resection and chemotherapy. O. intermedium was isolated from his blood cultures and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), however, the Vitek II automated system failed to identify the organism. Then the pathogen was confirmed by 16S rDNA sequencing and average nucleotide identity result (ANI) confirmed the precise identification of O. intermedium at genomic level. In addition, the patient recovered well after antibiotic combined therapy.

CONCLUSIONS

This, to our knowledge, is the first case of O. intermedium bacteremia in a pediatric patient with malignant tumor. Traditional biochemical identification methods such as API 20NE or VITEK2 system cannot differentiate O. anthropi and O. intermedium. MALDI-TOF may be a promising tool for rapid identification of microorganisms such as O. intermedium.

A Case of Ochrobactrum intermedium Bacteremia Secondary to Cholangitis With a Literature Review

Ochrobactrum species are gram-negative, non-lactose fermenting, aerobic bacilli closely related to Brucella genus. Ochrobactrum intermedium (O. intermedium) is an emergent human pathogen that is difficult to differentiate from other Ochrobactrum species by conventional methods. It is known to infect immunocompromised hosts, has the propensity for abscess formation, and is known for its multidrug resistance. We describe the case of an 84-year-old woman with a background of primary sclerosing cholangitis who presented with fatigue, fever, and syncope. Blood cultures grew O. intermedium. Magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography were consistent with cholangitis. Cultures from the biliary duct confirmed the same microorganism. The patient was successfully treated with minocycline. Although rare, O. intermedium should be considered as a differential diagnosis in patients with biliary and gut pathology, particularly in immunocompromised patients.