FIG 2.

Antibiotic susceptibilities of CF-derived bacterial pathogens are impacted by cooperative community interactions. MICs of six antibiotics were determined for P. aeruginosa (a) and anaerobic bacterial enrichments isolated from sputum (b). Daggers indicate bacterial growth at the highest concentration of antibiotic tested. Bar shading represents the predicted growth (gray) or predicted lack of growth (black) of each subpopulation in the coculture tube assay (c). Growth predictions were determined by comparing individual MICs to the preselected concentration of antibiotic used in the coculture assay (indicated by a dashed line). (c) qPCR was used to quantify the growth of sputum bacterial communities from which P. aeruginosa and anaerobes were derived in the presence of each antibiotic. Growth is expressed as the percent 16S rRNA gene copy number relative to the copy number of an untreated control. Community growth was considered impaired if total 16S rRNA gene copies were less than 50% of the control (dashed line). Data shown are mean qPCR measures from at least three replicate measurements for each coculture tube.