Within the notifiable animal diseases in companion animals such as brucellosis (Brucella canis), psittacosis (Chlamydia psittaci) and tuberculosis (Mycobacterium bovis), there is no legal framework for antibiotic use. Antibiotic treatments are not always effective and can lead to new ones
outgrowth of the bacteria, resulting in recurring complaints and contagiousness. Why this happens is unknown. In addition, such inefficient treatments can lead to resistance development. There is little insight into antibiotic resistance in B. canis and C. psittaci, although this exists
described for other species such as Brucella melitensis and Chlamydia suis.
Bacteria respond differently to exposure to antimicrobials. Sensitive bacteria
are quickly killed. However, a bacterium can also develop resistance. In this case, the bacteria are insensitive to the drug and continue to grow despite the presence of the antibiotic. This involves a genetic modification of a gene that is directly involved in the antibiotic used. Regrowth of B. canis, C. psittaci or M. bovis after treatment may indicate survival bacteria under antibiotic pressure. After removal of antibiotic treatment (end of treatment), tolerant or persistent bacteria resume growth. The survival of tolerant bacteria can then be achieved be a source for resistance development. At this time there is both human and animal indoors screened for the presence of antimicrobial resistance for a small number of pathogens. However, resistance development has already taken place here and all that remains is to intervene
on limiting spread. Ideally, resistance development is prevented and this is possible through timely detection of tolerance.

Treating infections with antibiotics is not always effective. This means that during
treatment not all bacteria are killed by the antibiotic. This allows bacteria
grow again after a course of treatment is repeated and again for complaints and contagiousness
to assure. This also includes the notifiable infectious diseases, Brucella canis in dogs, Chlamydia
psittaci in birds and Mycobacterium bovis in cats. A possible explanation for this is tolerance:
During antibiotic pressure, some bacteria stop growing but remain alive. This
bacteria are also called tolerant bacteria. The presence of tolerance is also
associated with the development of antibiotic resistance. That is why we want to do this in this project
Brucella researchers can accept this under antibiotic pressure and whether this makes a contribution
contributes to resistance development. We also want to investigate which genes are responsible
are for adjustment to a tolerant state. This knowledge is necessary for correct and effective use
antibiotics in both humans and animals.