EXPERIMENTAL-INFECTION BY HAEMOPHILUS-INFLUENZAE TYPE-B IN INBRED MICE

The epidemiological situation of bacterial meningitis is increasing dr amatically, There is no doubt that the lack of proper animal models ha s hampered the achievement of effective prophylactic and therapeutic m eans. We report the characterization of the experimental disease cause d by Haemophilus influenzae type b (Hib) in mice, taking into account its importance as an etiological agent of such a type of meningitis. T he high resistance of C57BL/6, CBA/J and BALB/cJ mice to Hib infection was proven. LD(50) of Hib using trypsin or iron dextran as virulence enhancement factors (VEF), both being similar and more than 1000 times lower than that without any VEF, were determined. Lesions of CNS comp atible with meningitis were found in about one third of specimens. Hai r bristling, conjunctivitis, diarrhea, depression and prostration were the most characteristic symptoms. The proportion of animals which die is highest on the first day, lower on the second and almost zero afte r 48 h of infection. Water and food intake was higher in control than in infected animals; nevertheless, there were no differences in body w eight increase among the mice after 5 days post-infection. Microorgani sms were isolated from CSF and blood after 6 h of infection and positi ve results remained according to the size of the inoculum. Despite the acuteness of the experimental disease, antibiotic treatment with inte rnationally recommended drugs was shown to be effective. Similar resul ts were achieved when hyperimmune serum vs. Hib was applied.