Figure 9From: Expression of urease by Haemophilus influenzaeduring human respiratory tract infection and role in survival in an acid environmentHuman antibody response to urease. Results of ELISAs measuring serum IgG to purified recombinant urease C in serum samples from adults with COPD who experienced exacerbations due to H. influenzae. Patient numbers (N = 18) are noted on the X-axis. The per cent changes from pre exacerbation to post exacerbation are shown on the Y-axis. The cutoff value (dotted line) for a significant increase in antibody level was determined by averaging the difference between 8 control pairs of sera from patients who had negative sputum cultures and were clinically stable (see text).Back to article page