Brucella vertebral osteomyelitis misidentified as an Ochrobactrum anthropi infection

Abstract

Ochrobactrum anthropi is a Gram-negative bacillus widely distributed in nature. It is a low virulence and low pathogenic microorganism and human infection by this agent is considered rare. This microorganism can cause bacteremia and in some cases can lead to osteomyelitis and endocarditis. Included in Brucellaceae family, this bacterium is phenotypically and genetically closely related to the Brucella genus and may be misidentified by rapid identification systems. The authors describe a patient admitted to the Infectious Diseases Department with vertebral osteomyelitis initially identified as Ochrobactrum anthropi. Despite appropriate antimicrobial therapy, the blood cultures remained positive and there were no signs of clinical improvement. This raised suspicion of a possible misidentification. It was decided to initiate antimicrobial therapy to include the Brucella genus, with slow but progressive clinical improvement. Samples were sent to Instituto Nacional de Saúde Doutor Ricardo Jorge (INSA) for genotyping, confirming the initial suspicion of misidentification and identifying Brucella melitensis as the causal agent. Timely diagnosis of brucellosis is essential for the correct management and prevention of its consequences for the patient and for safe handling of the laboratory samples, preventing laboratory-acquired infection

Ochrobactrum anthropi – An Emerging Opportunistic Pathogen in Musculoskeletal Disorders – A Case Report and Review of Literature

“…In 1988, Holmes et al described the genus Ochrobactrum and its subtype species O. anthropi [ 13 ]. O. anthropi is recognized as belonging to the new genus Ochrobactrum, which was also called Brucella anthropi and Achromobacter that occasionally causes human infection [ 14 ]. The genus Ochrobactrum was named after the Greek word “Ochros” meaning yellow color [ 2 ].…”

“…3 ) [ 10 ]. API 20NE automated system misidentify O. anthropi as Brucella species because of its close relation [ 8 , 14 ]. Hence, a confirmation is required with negative serum Brucella species antibodies in a patient with severe infections caused by O. anthropi bacteremia without any proper primary focus of infection and refractory to standard treatment [ 3 ].…”

“…Till date, two reports were mentioned without any risk factor for O. anthropi infection in the musculoskeletal system in the literature and the present case is the third such case [ 19 , 28 ]. In the musculoskeletal system, O. anthropi causes osteomyelitis, septic arthritis, osteochondritis, and soft tissue abscess [ 3 , 4 , 5 , 6 , 12 , 13 , 14 , 15 ]. The review of O. anthropi infection in the musculoskeletal system is tabulated in ( Table 1 ).…”

“…A few reports have been published in the literature stating the misidentification of Brucella group of organisms due to low homology with O. anthropi [ 8 , 14 , 37 , 38 ]. Gopalsamy et al reported misidentification of O. anthropi in Brucellosis infection as both the organisms are close phylogenetic relatives which result in cross-reactivity on Western blot and 16s ribosomal RNA sequence signatures [ 8 ].…”

The Genus Ochrobactrum as Major Opportunistic Pathogens

“…There have been cases of misdiagnosis of Ochrobactrum anthropi (subsequently confirmed by VITEK) as Shewanella putrefaciens [ 48 ]. Of course, the opposite has also been reported where a Brucella suis bacteraemia was mistakenly identified as Ochrobactrum anthropi by the VITEK 2 system [ 49 , 50 ]. These studies underscore the difficulty encountered in identifying unusual Gram-negative, non-fermentative bacteria such as Ochrobactrum .…”