Adaptation of Brucella melitensis Antimicrobial Susceptibility Testing to the ISO 20776 Standard and Validation of the Method.

Brucellosis, mainly caused by Brucella (B.) melitensis, is associated with a risk of chronification and relapses. Antimicrobial susceptibility testing (AST) standards for B. melitensis are not available, and the agent is not yet listed in the EUCAST breakpoint tables. CLSI recommendations for B. melitensis exist, but they do not fulfill the requirements of the ISO 20776 standard regarding the culture medium and the incubation conditions. Under the third EU Health Programme, laboratories specializing in the diagnostics of highly pathogenic bacteria in their respective countries formed a working group within a Joint Action aiming to develop a suitable method for the AST of B. melitensis. Under the supervision of EUCAST representatives, this working group adapted the CLSI M45 document to the ISO 20776 standard after testing and validation. These adaptations included the comparison of various culture media, culture conditions and AST methods. A Standard Operation Procedure was derived and an interlaboratory validation was performed in order to evaluate the method. The results showed pros and cons for both of the two methods but also indicate that it is not necessary to abandon Mueller-Hinton without additives for the AST of B. melitensis.

Blackbirds Turdus merula as competent reservoirs for Borrelia turdi and Borrelia valaisiana in Portugal: evidence from a xenodiagnostic experiment.

To confirm that thrushes, such as blackbirds Turdus merula, play a role as reservoir for some Borrelia genospecies, we performed a xenodiagnostic experiment with blackbirds captured in a mixed wood located in Western Portugal where Borrelia turdi, an uncommon genospecies in Europe, was the most prevalent genospecies associated with birds. Two out of five birds harboured B. turdi infected Ixodes frontalis at the time of capture. Four out of five birds transmitted spirochaetes to Ixodes ricinus xenodiagnostic ticks: two birds transmitted Borrelia valaisiana to 25.7% and 10.5% of ticks, and two transmitted B. turdi to 6.4% and 5.4% of ticks. Our results showed that blackbirds transmit B. valaisiana and B. turdi to I. ricinus feeding larvae, acting as reservoir hosts for these genospecies in nature.

A portuguese isolate of Borrelia lusitaniae induces disease in C3H/HeN mice.

A low-passage, Portuguese isolate of Borrelia lusitaniae, strain PotiB2, was inoculated into C3H/HeN mice and disease was monitored by histopathology at 8 weeks after spirochaete challenge. Ear, heart, bladder, femoro-tibial joint, brain and spinal cord were examined. B. lusitaniae strain PotiB2 (6 of 10 mice) and B. burgdorferi sensu stricto strain N40 (9 of 10 mice) induced similar lesions in the bladder of infected mice characterised as a multifocal, lymphoid, interstitial cystitis. Moreover, both B. lusitaniae PotiB2 and B. burdorferi N40 induced lesions in the heart of infected mice. The lesions induced by B. lusitaniae PotiB2 (2 of 10 mice) were characterised as a severe, necrotising endarteritis of the aorta, with a minimal, mixed inflammatory infiltrate (neutrophils, macrophages and lymphoid cells) extending into the adjacent myocardium. In contrast, B. burgdorferi N40 induced a periarteritis of the pulmonary artery (7 of 10 mice), with no involvement of the endothelium and more extensive inflammation and subsequent necrosis of the adjacent myocardium. This infiltrate was composed entirely of mononuclear cells, predominantly mature lymphocytes and plasma cells. No lesions were noted in the joints or central nervous system with inoculation of strains N40 or PotiB2, and co-inoculation of either strain with Ixodes ricinus salivary gland lysate did not affect the resulting pathology. Serology, examined 8 weeks after inoculation, indicated a different reactivity in mice infected with B. lusitaniae PotiB2 compared with B. burgdorferi N40. Immunoblot analysis demonstrated that mice with lesions resulting from infection with B. lusitaniae PotiB2 reacted only to the flagellin protein (41 kDa) or to flagellin and OspC, whereas mice infected with B. burgdorferi N40 reacted with multiple high and low mol. wt proteins, including flagellin, p93, p39, OspA, OspB and OspC. These results indicate that B. lusitaniae PotiB2 induced pathology similar to B. burgdorferi N40 when inoculated into susceptible mice. Moreover, these results establish the first animal model of disease with B. lusitaniae. This mouse model can be used to characterise the immunopathogenesis of B. lusitaniae infection and to delineate the proteins responsible for disease induction in susceptible mice.