Pseudomonas aeruginosa and Burkholderia cenocepacia infections in patients affected by cystic fibrosis: serum resistance and antibody response.

Pseudomonas aeruginosa and Burkholderia cenocepacia are opportunistic pathogens causing important chronic pulmonary infections in patients affected by cystic fibrosis (CF). The interplay of bacterial and host factors involved in the establishment and evolution of these infections needs further clarification. We investigated the susceptibility of P. aeruginosa and B. cenocepacia derived from CF patients or from the environment to hyperimmune sera obtained from the same CF patients and evaluated the amount of specific antibodies present in these sera. Our data indicate that the bactericidal activity of human serum against these two bacteria is mostly complement-mediated, and that the mucous layer probably confers serum-resistance to B. cenocepacia. The mean amount of antibodies against P. aeruginosa was higher than that against B. cenocepacia. The contribution of these data to the assessment of the importance of the humoral immune response in CF pulmonary infections by Pseudomonas and Burkholderia is briefly discussed.

DNA ploidy by image cytometry in urothelial carcinomas. Comparison of touch imprints and paraffin-embedded biopsies from 31 patients.

OBJECTIVE: To compare DNA content measured by image cytometry from touch imprints and formalinfixed, paraffin-embedded samples in bladder carcinomas. STUDY DESIGN: Thirty-one biopsies of urothelial carcinomas were selected for a prospective study. Imprints of fresh specimens were performed. Cell suspensions were obtained from dewaxed samples by the procedure of Hedley. Sections 7 microns thick were used for carcinoma in situ and small biopsies. The DNA ploidy index was measured on Feulgen-stained slides using an image cytometer. RESULTS: From imprint analysis, seven grade 1 carcinomas (n = 9) were found to be diploid (78%). Nine grade 2 carcinomas (n = 12) exhibited aneuploidy (75%), as did all grade 3 and in situ carcinomas (n = 10). Multiploidy was demonstrated from imprints in four cases instead of the two detected from dewaxed tissue. In 27 cases (87%), G0/G1 peaks obtained from paraffin blocks showed a shift to the left. In five cases (16%), variations in the DNA index were responsible for discrepancies in the DNA ploidy evaluation between fresh imprints and dewaxed samples of the same tumors. CONCLUSION: Image cytometry on Feulgen-stained imprints of bladder biopsies is a simple and reliable procedure for assessing DNA ploidy in urothelial carcinomas, providing great sensitivity for detecting small aneuploid peaks and multiploid tumors. DNA image analysis of touch preparations is especially useful for carcinoma in situ and small biopsies unsuitable for Hedley's technique.