Figure 6

NTHi mutants are attenuated in the chinchilla otitis media model. Chinchillas (4–5 animals representing 8–10 middle ears per challenge strain) were transbullarly injected with 100 μl (~ 1000 CFU) of the 86-028NP wild type, ΔvapBC-1, ΔvapXD, or the ΔvapBC-1 ΔvapXD mutant strain, respectively. On day 4 post-challenge, the middle ears were washed and bacterial CFU counts were obtained. Data are expressed as mean ± SD.