TABLE 2.
Comparison between the Brucella and Ochrobactrum generaa
| Divergent property | Finding for: |
|
|---|---|---|
| Brucella | Ochrobactrum | |
| Genome size (Mb) | 3.1–3.4 | 4.7–8.3 |
| Pangenome type (no. of genes) | Closed (~11,000) | Open (>74,000) |
| No. of genes in core genome | ~1,000 | ~75 |
| DNA-DNA hybridization (%) | ~20–30b | |
| No. of RNA genes | 54 | 78–85 |
| Presence of IS711 insertion sequences | In all species and strains | Absent |
| No. and type of plasmids | None | Variable (up to 6) and conjugative |
| Phylogeny | Monophyletic | Polyphyletic |
| No. of lysogenic phages | None | >4 (present in at least in some species) |
| Lateral gene transfer | Absent | Present |
| Speciation type | Allopatric | Sympatric |
| Overall cell envelope properties | Permeable to hydrophobic probes and resistant to polycationic peptides | Impermeable to hydrophobic probes and sensitive to polycationic peptides (O. anthropi and O. intermedium) |
| No. of transport reactions | ~47 | ~111 |
| Metabolic redundancy | Low | High |
| No. of metabolic pathways | 254 (35 unique for the genus) | 313 (94 unique for the genus) |
| Removal of toxic metals | No | Yes (species/strains) |
| Degradation of phenolic compounds, petroleum wastes, and xenobiotics | No | Yes (species/strains) |
| Capable of root nodulation | No | Yes (species/strains) |
| Lifestyle | Pathogen | Saprophyte |
| Natural habitat | Intracellular | Soil and root plant surfaces |
| Transmission to humans | Host-host interaction/animal products | Mostly iatrogenicb |
| Virulence | Finely tuned | Fortuitous/opportunisticb |
| Virulence mechanisms | Escape from the immune response/deviation of intracellular trafficking | No true virulence mechanisms (virulence depends on the host's immune status) |
| Type IV secretion system | Required for intracellular trafficking and lifestyle | Devoted to plasmid conjugation with a different origin |
| Infection dynamics | Long-lasting infection and low proinflammatory response | Acute proinflammatory/pyogenic; self-limiting in immunocompetent hostsb |
| Animal disease | Globally distributed and prioritized in many countries (20); about 1.25 billion and 1.9 billion susceptible cattle and small ruminants, respectively, in nonindustrialized countries (with endemic disease)c | Not reported as agents of contagious disease |
| Human health | Present in at least 101 countries worldwide (in 2018) and hugely underreported (21); based on fragmentary (but valid) seroprevalence studies, the annual number of cases may be in the range of 330,000–19,000,000 cases (22) | A total of 288 cases published between 1998 and 2020 (9) |
| Diagnosis | Well-standardized serological methods | No serological tests are available or necessary |
| Treatment | WHO-recommended long bitherapy in uncomplicated cases (doxycycline and streptomycin or doxycycline and rifampin) | Depending on antibiotic resistance, short-term broad-spectrum intravenous monotherapy with β-lactams, such as imipenem-cilastatin or cefepime, or oral therapy with co-trimoxazole or ciprofloxacin (9) |
| Acquired antibiotic resistance | Not reported for doxycycline and streptomycin, including isolates from relapse cases; reported rifampicin resistance in a few strains, possibly due to in vitro overestimation (23), and very rarely confirmed by ropB mutations (24) | Plasmid-encoded resistance to different families of antibiotics, such as β-lactams (penicillins and cephalosporins, with emerging cases of carbapenem resistance) (9) |
| Vaccine | Available (for domestic ruminants) and critically important to control disease | Not available or recommended |
| WHO/OIE/FAO recommendations/regulations | Detailed, as follows: (i) humans: diagnosis, treatment, and prophylaxis; (ii) animals: diagnostic procedures/protocols (with emphasis on prescribed tests for international trade) and vaccination | None |
| WHO biosafety risk group (human disease) | RG3 (high individual risk and low community risk) | RG1 (no or low individual and community risk) |
a
Data extracted from reference 3 (copyright owned by the authors).
b
Compared with the O. anthropi/O. intermedium group, the closest phylogenetic relatives of Brucella species (6).
c
Figures were calculated by totaling FAOSTAT population data for 2013 for the European Union, North America, Australia, and New Zealand (industrialized countries) and subtracting this value from the world sheep and goat population (https://www.fao.org/faostat/es/#data [accessed 6 June 2023]).