Isolation of Klebsiella pneumoniae from lake water

The question of the importance of aquatic borne Klebsiella pneumoniae to public health has been argued as the organism has appeared often in both polluted effluents and oligotrophic systems. Using a selective medium, double violet agar, which also differentiates K. pneumoniae from other organisms found in aquatic systems, we sampled water from three ponds and a large man-made lake, over a 3-month period. Results indicate that K. pneumoniae can be isolated consistently and in high numbers from eutrophic waters even when environmental stress reduces total numbers, but that isolations from cleaner waters are erratic. We conclude that mere isolation of the organism as an occasional contaminant probably does not present a hazard to public health.