Clinical characteristics of patients with Ochrobactrum anthropi bloodstream infection in a Chinese tertiary-care hospital: A 7-year study

Ochrobactrum anthropi sepsis in a 15-month-old child: A case report

Key Clinical Message

Ochrobactrum anthropi (O. anthropi), a rare opportunistic pathogen, caused sepsis in a malnourished 15-month-old African child. Early detection and appropriate antibiotics led to full recovery, highlighting the importance of robust surveillance for emerging pathogens in vulnerable populations.

Abstract

While rarely causing infections, O. anthropi, a non-fermenting, obligately aerobic, flagellated gram-negative bacillus, demonstrates oxidase positivity and indole negativity. Traditionally, Ochrobactrum spp is considered a low threat due to its environmental abundance and mild virulence. It is, however, a multidrug-resistant bacteria known for causing opportunistic infections in humans. O. anthropi is typically associated with catheter-related bloodstream infections. The first documented case was in 1998; most cases have been reported in developed countries. We present a case of O. anthropi sepsis in a malnourished child in sub-Saharan Africa. We report a case involving a 15-month-old African female who presented with symptoms and signs of protein-energy malnutrition and sepsis. The blood culture revealed O.anthropi. We treated the child with the empirical first-line antibiotics per the national guidelines, intravenous ampicillin and gentamicin for a week, and the child fully recovered. This report describes a rare case of O. anthropi sepsis with malnutrition in an African female child. O. anthropi is an emerging pathogen causing opportunistic infections in both immunocompetent and immunocompromised patients. We report that early bacterial detection, appropriate antibiotic susceptibility and antimicrobial management based on local antibiogram data may be essential for excellent patient outcomes. Additionally, we recommend more robust surveillance to detect such rare emerging pathogens.

Ochrobactrum Anthropi; an Unusual Cause of Bacteremia and Pneumonia: A Case Report and a Brief Review of the Literature

Background: Ochrobactrum anthropi spp. is a non-enteric, aerobic gram-negative bacillus that has been reported to cause sepsis and occasionally bacteremia in both immunocompetent and immunocompromised hosts. This bacterium is capable of surviving in various habitats, but due to its affinity for aqueous environments, O. anthropi is hypothesized to have an affinity for indwelling plastic devices and other foreign bodies.

Case Presentation: We report a case of a 66 y/o male with a history of polysubstance abuse disorder admitted for toxic metabolic encephalopathy and found to have bronchopneumonia and bacteremia secondary to O. anthropi infection resulting in sepsis and cardiopulmonary arrest.

Discussion: Ochrobactrum spp. is an unusual pathogen of low virulence and has been noted to cause bacteremia and occasionally sepsis in both immunocompetent and immunosuppressed patients. Isolation of this pathogen in the appropriate setting should be considered a true pathogen and treated as such to avoid sequela of this infection.

Conclusion: This case report and literature review suggest that Ochrobactrum anthropi appears more frequently as a pathogen in nosocomial infections than suggested in the literature.

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Two Case Reports of Ochrobactrum anthropi Bacteremia: An Overlooked Pathogen

Ochrobactrum anthropi, due to its robust survival abilities, has been known to cause nosocomial and opportunistic infections, posing both diagnostic and therapeutic challenges. Low virulence, indolent clinical presentation, and lack of awareness on their clinical significance attribute to the underreporting of the same. We report two cases of bacteremia in oncology patients presented to us in a short span of 6 months, which indicates that such infections might be quite common in immunocompromised hosts. Both our strains were susceptible to carbapenems, trimethoprim/sulfamethoxazole, and minocycline, and recovered with monotherapy. More vigilant and accurate diagnostic techniques need to be followed not to miss such pathogens. Early identification and administration of appropriate antibiotics have been associated with a good outcome.

Pathogenicity and Its Implications in Taxonomy: The Brucella and Ochrobactrum Case

The intracellular pathogens of the genus Brucella are phylogenetically close to Ochrobactrum, a diverse group of free-living bacteria with a few species occasionally infecting medically compromised patients. A group of taxonomists recently included all Ochrobactrum organisms in the genus Brucella based on global genome analyses and alleged equivalences with genera such as Mycobacterium. Here, we demonstrate that such equivalencies are incorrect because they overlook the complexities of pathogenicity. By summarizing Brucella and Ochrobactrum divergences in lifestyle, structure, physiology, population, closed versus open pangenomes, genomic traits, and pathogenicity, we show that when they are adequately understood, they are highly relevant in taxonomy and not unidimensional quantitative characters. Thus, the Ochrobactrum and Brucella differences are not limited to their assignments to different "risk-groups", a biologically (and hence, taxonomically) oversimplified description that, moreover, does not support ignoring the nomen periculosum rule, as proposed. Since the epidemiology, prophylaxis, diagnosis, and treatment are thoroughly unrelated, merging free-living Ochrobactrum organisms with highly pathogenic Brucella organisms brings evident risks for veterinarians, medical doctors, and public health authorities who confront brucellosis, a significant zoonosis worldwide. Therefore, from taxonomical and practical standpoints, the Brucella and Ochrobactrum genera must be maintained apart. Consequently, we urge researchers, culture collections, and databases to keep their canonical nomenclature.

The Genus Ochrobactrum as Major Opportunistic Pathogens

Ochrobactrum species are non-enteric, Gram-negative organisms that are closely related to the genus Brucella. Since the designation of the genus in 1988, several distinct species have now been characterised and implicated as opportunistic pathogens in multiple outbreaks. Here, we examine the genus, its members, diagnostic tools used for identification, data from recent Ochrobactrum whole genome sequencing and the pathogenicity associated with reported Ochrobactrum infections. This review identified 128 instances of Ochrobactrum spp. infections that have been discussed in the literature. These findings indicate that infection review programs should consider investigation of possible Ochrobactrum spp. outbreaks if these bacteria are clinically isolated in more than one patient and that Ochrobactrum spp. are more important pathogens than previously thought.

Ochrobactrum anthropi Infection of the Hand

Ochrobactrum anthropi is an opportunistic, low-virulence pathogen occasionally associated with human infections and found largely in immunocompromised patients and those with intravascular devices. We report the case of a healthy 70-year-old man who presented with an infection of the hand, who had no history of trauma but had been gardening for 4 months. Despite surgical debridement and empirical antibiotics, the infection could not be controlled. Cultures revealed O anthropi. Antibiotic treatment was adapted to intravenous cefepime for 15 days and the infection was finally controlled after a second surgery. Oral cotrimoxazole was continued for another 2 weeks. Ochrobactrum anthropi infection of the hand must be considered not only in immunosuppressed patients but also in healthy patients without intravascular devices. Local debridement and empiric antibiotic may be insufficient. Antibiotic therapy should follow susceptibility testing, but usually includes a broad-spectrum intravenous beta-lactam such as imipenem–cilastatin or cefepime, or oral cotrimoxazole or ciprofloxacin.