What is the Bartonella tribocorum pathogen?
Bartonella tribocorum is a bacterium that belongs to the Bartonella genus. Like other Bartonella species, B. tribocorum can cause disease in the animal. The bacterium was first isolated from the blood of wild rats. The Bartonella tribocorum pathogen appears to be genetically related to B. elizabethae, which was isolated from a patient with endocarditis. So far, it has not been observed that the Bartonella tribocorum pathogen is a human pathogen.
What are the histological characteristics of the Bartonella tribocorum pathogen?
The Bartonella tribocorum pathogen could be isolated from living wild rats (Rattus norvegicus) in a rural environment. The pathogen differed from the previously known Bartonella species, with regard to its phenotypic and genotypic characteristics. The Bartonella tribocorum pathogen was characterised by its trypsin-like activity. In addition, the bacterium lacked the ability to hydrolyse proline and tributyrin. It consists of16S rRNA and citrate synthase gene sequences. Its strain type is IBS 506. Bartonella tribocorum pathogen lacks flagella but has polar fimbriae, is aerobic and catalase, oxidase and urease negative.
Bartonella tribocorum was named after the strains mentioned by Caesar (51 BC) in his "Commentarii de Bello Gallico". These were tribes that lived near the Rhine in the eastern part of present-day France. This is exactly where the wild rats from which the Bartonella tribocorum pathogen could be isolated were caught .
How was the Bartonella tribocorum pathogen diagnosed?
For the diagnosis of the Bartonella tribocorum pathogen, two Bartonella strains could be isolated from the blood of two wild rats (Rattis norvegicus) . The two strains differed from all Bartonella species known so far . The rats were already dead at the time of diagnosis . Their breed was determined on the basis of morphology and their dentition.
To diagnose the Bartonella tribocorum pathogen, the blood of the wild rats was collected by intracardiac puncture and poured into a Pediatric Isolator 1.5 tube (Wampole Laboratories) to dissolve the red blood cells (haemolysis). A drop of blood was spread on the glass slide without prior centrifugation. Incubation of the glass slides took place at 35 °C in a humid atmosphere with 5 per cent CO2 content.
Two of the four plates coated with rat blood had to be discarded due to heavy bacterial contamination, as various bacterial colonies grew within 24 hours. The other two plates showed small bacterial colonies ten days after inoculation. The two strains were given the names IBS 500 and IBS 506 T.
Meanwhile the Bartonella tribocorum pathogen was also detected in rats at various sites in Flanders/Belgium. Studies suggest that the rat appears to be an important reservoir host for zoonotic Bartonella tribocorum in Belgium. As these rodents inhabit buildings and sometimes households, and are generally more likely to be in close contact with humans, especially in suburban and urban regions, further research should be sought. In particular, this should focus on monitoring vector-borne pathogens in which rat populations could serve as hosts and reservoirs. In this way, an important contribution could be made with regard to surveillance, prevention as well as risk control in the context of public health management .
How did the Bartonella tribocorum pathogen differ from other Bartonella species?
The Bartonella tribocorum strains isolated from the blood of the two wild rats had similar phenotypic characteristics to other Bartonella species. They could previously be detected in red blood cells (erythrocytes). In addition to slow growth they were conspicuous by their appearance as a small aerobic, fastidious, oxidase-negative, gram-negative rod. The pathogen thrived best on a blood-enriched medium in an atmosphere that contained 5 per cent CO2. Similar to Bartonella doshiae, a negative proline aminopeptidase activity was also found for B. trobocorum. However, the pathogens Bartonella tribocorum and B. doshiae can be distinguished from each other in that B. doshiae hydrolysed tributyrin and B. tribocorum did not.
The 16S rRNA gene sequence of Bartonella tribocorum resembled those of other known Bartonella species. The type strain of B. elizahethae showed 99.6 percent similarity to the B. trobocorum type strain, while B. bacilliformis and B. clarridgeiae showed the strongest divergent sequences from B. tribocorum with 97.9 percent. A distinction between Bartonella tribocorum and B. elizahethae can be made with regard to their hybridisation rates. This ranged from 36 to 46 per cent, indicating that B. elizahethae and B. tribocorum belong to two different species.
What role do rates play in the transmission of the Bartonella tribocorum pathogen?
Researchers know that the Bartonella tribocorum pathogen is adapted to rats and persists in infected red blood cells (erythrocytes). This does not affect the natural lifespan of the erythrocytes, which is between 54 and 65 days. Bartonella tribocorum is released again into the bloodstream after the apoptosis of the erythrocytes in order to penetrate new erythrocytes in this way in order to multiply here. In this way, the Bartonella tribocorum pathogen manages to infect just under one percent of the erythrocytes in rats. B. tribocorum also remains in the host for a long time without seriously damaging it. Studies have shown that rats of the species Rattus norvegicus are an important reservoir host for Bartonella tribocorum.
There are only a few case reports of Bartonella tribocorum infection in humans. The infection manifests itself through rather unspecific symptoms such as fever and apathy. To date, there is one study from France that describes six patients suffering from different symptoms. B. tribocorum was detected in two of them.