[Legionella contamination in warm water systems of a large German city]

Since 1988 the Frankfurt City Health Department examined the hot water systems of all public indoor swimming pools, old age homes and hospitals, and made subsequent checks on the corrective measures introduced. In the 6 public indoor swimming pools the percentage of positive legionella findings, after corrective measures has dropped since 1988: at the central hot-water supply units from 47% to 23%, and at the peripheral tap connections from 66% to 22%. The number of negative samples rose from 43% to 77%. Thus the favourable effect of the corrective measures is demonstrated. Since 1988 samples have been taken from the shower water at old age homes. An increase in negative findings could be shown (from 58% to 70%). From 1990, however, an increase of high-level legionella contamination (> 10,000 Legionella colonies per litre) was detected as well. In one home with a generally high legionella contamination level (up to 75,000 legionella colonies per litre) an investigation of the legionella antibodies was done in the blood of 44 residents whose medical history included fever or bronchial symptoms. In no case a previous infection could be demonstrated. However, there was one patient with a definite legionella pneumonia in the home: this patient usually had been showering for at least 20 minutes a day. Legionella were found in the hot water systems of 16 of the 17 hospitals in Frankfurt. In 1991 more than half to the 204 samples were legionella positive. 5% of the samples had legionella contamination levels of more than 100,000 per litre. Corrective measures have been taken.(ABSTRACT TRUNCATED AT 250 WORDS)