The Impact of General Laboratory Animal Health on Experimental Models in Antimicrobial Chemotherapy

This chapter describes how the poor health of a laboratory animal can adversely the experimental models used in antimicrobial research. Concerns for the health of laboratory animals have mostly focused on spontaneous infections, although disease in laboratory animals may also be caused by genetic or environmental determinants. The presence of various pathogenic microorganisms may cause changes in the organs, resulting in difficulties in the interpretation of the pathological diagnosis included in the evaluation of many microbiological models. The immune system may be modulated by spontaneous infections in the absence of clinical disease. This effect may be either suppressive or activating or both at the same time, but on different parts of the immune system. Some microorganisms have a specific effect on enzymatic, haematological, and other parameters, which are monitored in the animal during an experiment. Organic function disturbances may change the outcome of the experiment without the knowledge of the scientist. Spontaneous infections in an experimental infection model may also compete with the experimental infection, which in the worst cases may fail. Microorganisms present in the animal may contaminate samples and tissue specimens, such as cells and sera. This may complicate the in vitro maintenance of cell lines, and may interfere with experiments performed on cell cultures or isolated organs. To avoid disease, microbial interference, and zoonoses, laboratory animals are produced according to a three-step principle, which include rederivation, barrier protection, and health monitoring. Rederivation means the production of animals to initiate breeding colonies by either caesarian section or embryo transfer.