Age Does Not Influence the Disease Course in a Mouse Model of Serotype 3 Meningitis
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In order to elucidate the causes for the increased mortality of aged patients with bacterial central nervous system (CNS) infections, we compared the course of () meningitis in aged and young mice. Aged (21.2 ± 3.1 months, = 40) and young (3.2 ± 0.9 months, = 42) C57BL/6N and B6/SJL mice were infected by intracerebral injection of 50-70 CFU serotype 3 and monitored for 15 days. Aged and young mice did not differ concerning mortality (35% versus 38%), weight loss, development of clinical symptoms, bacterial concentrations in cerebellum and spleen as well as the number of leukocytes infiltrating the CNS. In contrast to results from our geriatric mouse model of () meningitis, where aged mice showed a higher mortality and an impaired elimination of bacteria, we did not find any differences between aged and young mice after intracerebral infection with serotype 3. This indicates that the increased susceptibility of aged mice to bacterial CNS infections is pathogen-specific: It appears less prominent in infections caused by hardly phagocytable pathogens with thick capsules like serotype 3, where the age-related decline of the phagocytic capacity of microglia and macrophages has a minor influence on the disease course.