FIG 3.

Molecular network analysis of all six lungs from three patients afflicted with CF. (a) The molecular network is color coded by patient as follows: blue, patient 1; green, patient 2; orange, patient 3. The network clusters corresponding to antibiotics are highlighted in boxes. (b) The numbers of samples that contained a given set of consensus MS/MS spectra (represented as nodes in panel a) are plotted. The frequency of occurrence of antibiotics detected in this data set is highlighted on the plot. The number of nodes in a cluster is reflective of the number of transformations of the parent compound that were detected. The node of each parent compound is highlighted an asterisk. The fragmentation patterns of the most frequently observed drugs, azithromycin and its analogs, are shown in Fig. S4; the large number of nodes shown in the piperacillin cluster stems from its structural similarity to small peptidic compounds abundant in biological samples and its inherent chemical reactivity with biological molecules (48). (c) Venn diagram of the overlap of consensus fragmentation spectra between three patients.