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.

Identification and assessment of a biocontrol agent, Ochrobactrum intermedium I-5, for management of alfalfa root rot caused by Fusarium tricinctum

Alfalfa root rot caused by Fusarium tricinctum is one of the most important soil-borne diseases resulting in significant losses to alfalfa agriculture worldwide. Fungicides used in management of disease affect the environment and human health. In this study, a strain of Ochrobactrum intermedium (I-5), isolated from alfalfa rhizosphere soil, exhibited strong antifungal activity against a number of causative pathogens of alfalfa root rot, and showed the strongest antagonistic activity against F. tricinctum (the longest radius/shortest radius ratio of 3.09). When applied at 10%, a filtrate of I-5 liquid culture significantly reduced the spore production and germination and mycelial growth of F. tricinctum, and the inhibition rate was 76.67%, 78.93% and 55.77%, respectively. Furthermore, a filtrate and suspension of the strain, when applied at 10%, reduced alfalfa root rot by more than 73%. The strain clearly promoted the activities of invertase, urease, cellulose, and neutral phosphatase in alfalfa rhizosphere soil and significantly reduced the damage to rhizosphere soil quality attributable to alfalfa root rot. Moreover, the strain clearly promoted the growth of alfalfa, without causing any evident damage to plants. The active substance produced by the strain was relatively insensitive to heat and ultraviolet irradiation and displayed optimal efficacy at pH 8. To the best of our knowledge, this is the first study describing the use of O. intermedium for the biological control of alfalfa root rot. O. intermedium (I-5) has considerable potential for application in the control of alfalfa root rot and improvement of the quality of cultivated alfalfa.

Functional analysis of the ocnE gene involved in nicotine-degradation pathways in Ochrobactrum intermedium SCUEC4 and its enzymatic properties

The SCUEC4 strain of Ochrobactrum intermedium is a newly isolated bacterium that degrades nicotine can use nicotine as the sole carbon source via a series of enzymatic catalytic processes. The mechanisms underlying nicotine degradation in this bacterium and the corresponding functional genes remain unclear. Here, we analyzed the function and biological properties of the ocnE gene involved in the nicotine-degradation pathways in strain SCUEC4. The ocnE gene was cloned by PCR with total DNA of strain SCUEC4 and used to construct the recombinant plasmid pET28a-ocnE. The overexpression of the OcnE protein was detected by SDS–PAGE analysis, and study of the function of this protein was spectrophotometrically carried out by monitoring the changes of 2,5-dihydroxypyridine. Moreover, the effects of temperature, pH, and metal ions on the biological activities of the OcnE protein were analyzed. The optimal conditions for the biological activities of OcnE, a protein of approximately 37.6 kDa, were determined to be 25 °C, pH 7.0, and 25 μmol/L Fe2+, and the suitable storage conditions for the OcnE protein were 0 °C and pH 7.0. In conclusion, the ocnE gene is responsible for the ability of 2,5-dihydroxypyridine dioxygenase. These findings will be beneficial in clarifying the mechanisms of nicotine degradation in O. intermedium SCUEC4.

Reclassification of Brucella ciceri as later heterotypic synonyms of Brucella intermedia

Recently Hördt et al. 2020 proposed to merge Ochrobactrum and Brucella genera based on up to date phylogenomic evidence and overall genomic divergence among Brucella-Ochrobactrum clade. This led to the description of the new combinations Brucella ciceri comb. nov., basonym: Ochrobactrum ciceri Imran et al. 2010 and Brucella intermedia comb. nov., basonym: Ochrobactrum intermedium Velasco et al. 1998. However, the type species for Brucella ciceri DSM 22292T and Brucella intermedia LMG 3301T show whole-genome coherence at the species level (ANI = 98.21 %, Mash D = 0.0154006, dDDH relatedness >70%), suggesting that may belong to the same genomospecies. Also, both taxa formed a single clade in the phylogenomic tree based on single-copy gene sequences. Previously reported phenotypic data offer a context where both taxa are highly related supporting this synonymy. Therefore, Brucella ciceri should be reclassified as later heterotypic synonyms of Brucella intermedia, which has priority. The species description is consequently amended.