Bovine mastitis is one of the most important diseases in the dairy industry and has detrimental impact on the economy and welfare of the animals. Further, treatment failure results in increased antibiotic use in the dairy industry, as some of these mastitis cases for unknown reasons are not resolved despite standard antibiotic treatment. Chronic biofilm infections are notoriously known to be difficult to eradicate with antibiotics and biofilm formation could be a possible explanation for mastitis cases that are not resolved by standard treatment. This paper reviews the current literature on biofilm in bovine mastitis research to evaluate the status and methods used in the literature. Focus of the current research has been on isolates from milk samples and investigation of their biofilm forming properties in vitro. However, in vitro observations of biofilm formation are not easily comparable with the in vivo situation inside the udder. Only two papers investigate the location and distribution of bacterial biofilms inside udders of dairy cows with mastitis. Based on the current knowledge, the role of biofilm in bovine mastitis is still unclear and more in vivo investigations are needed to uncover the actual role of biofilm formation in the pathogenesis of bovine mastitis.

Macrophages play a key role in the inflammatory response in Lyme arthritis (LA) and could be a target for diagnosing and monitoring active Borrelia burgdorferi sensu lato (Bb) infection. Therefore, we evaluated the potential of macrophage imaging using 64Cu-DOTATATE PET/CT for detection of Bb activity in a murine model of LA. LA was established in C3H/HeNRj mice infected with Bb B31 strain ML23 pBBE22luc. Bioluminescence imaging was performed to detect migration of spirochetes and inflammatory phagocytes to the joints. Three weeks post-infection 64Cu-DOTATATE PET/CT imaging was performed at an early (3 h) and late (48 h) time point. Plasma levels of a systemic macrophage marker in plasma CD163 were measured. 64Cu-DOTATATE uptake in infected joints was increased at the early (p < 0.0001) and late time points (p = 0.0005) compared with uptake in non-infected controls. No significant difference in plasma levels of CD163 was measured. 64Cu-DOTATATE PET allows for in vivo detection and quantification of LA locally in the joints through non-invasive visualization of macrophages. In contrast, measurement of a systemic macrophage marker in plasma, CD163, did not allow to detect disease. We suggest that 64Cu-DOTATATE PET could become a valuable diagnostic tool for in situ detection of Bb infection-related inflammation.

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