Legionella and refrigerated water fountains?

Have you heard of any linkage to Legionella associated with refrigerated portable water fountains or coolers? Is there any information or guidance about flushing refrigerated water fountains on a routine basis to decrease risks?

Many years ago, there was a dramatic increase in the concentration of Legionella (and a shift in species) isolated from our chilled drinking water system. Our usual experience was to find low concentrations of L. bozemanii (blue-white fluorescing species rarely associated with infection). Then one day our water fountain cultures were covered with (>3000 cfu) with Legionella pneumophila, serogroup 1. The compressor/chiller had malfunctioned a few weeks previously and that a new one was on order. This system was a recirculating system with 2-3 fountains/floor on this system. After the chiller failed, the water was no longer cold enough to inhibit Legionella pneumophila from growing in the system. We did try to hyperchlorinate the system, with the expected result-recolonization after a few weeks. Ultimately, we replaced the old recirculating system with stand-alone units. Now we rarely have a positive culture from these units and the water is very cold.