Spatial patterns in antibiotic resistance among stream bacteria: Effects of industrial pollution

The spatial distribution of antibiotic resistance to streptomycin and kanam ycin was examined in natural bacterial communities of two streams. The prop ortion of resistant bacteria was substantially higher (P < 0.05) in the mid reaches of an industrially perturbed stream, but no such pattern was appare nt in an undisturbed reference stream, The highest relative frequency of re sistance was found at the confluence of a tributary draining a nuclear reac tor and industrial complex. Antibiotic resistance increased with distance u pstream from the confluence and was positively correlated (r(2) = 0.54, P = 0.023) with mercury concentrations in the sediments. When the data for two gears were compared, this pattern was stable for streptomycin resistance ( paired t test, P < 0.05) but not for kanamycin resistance (P > 0,05), Our r esults imply that heavy metal pollution may contribute to increased antibio tic resistance through indirect selection.