Legionella gormanii and L. pneumophila, serogroup 3 are in our hospital water supply. In a newly constructed hospital (280 beds) we have detected the presence of Legionella in the hot water system only after a few months. The results of the samples collected immediately after commissioning were negative.
After 5 months, the routine surveillance of the water quality revealed a weak contamination of the hot water distribution system with L. pneumophila serogroup 3 (< 1000 cfu/l). To our surprise we found Legionella gormanii (concentrations between 1500 and 12000 cfu/l) on several water outlets in patient rooms (like wallmount faucets and thermostatic shower valves).
We have never heard of this species. By reviewing the literature, we found only 2 articles: First isolation of Legionella gormanii from human disease – Griffith et al. – 02/1988. Legionella gormanii sp. Nov. – Morris et al. – 11/1980. Is the virulence of L. gormanii comparable to that of Legionella pneumophila?
Legionella gormanii is one of the avirulent Legionella species, although cases of infection have been described. Isolation of this species from your water supply is not a major cause of concern. L. pneumophila serogroup 3 is also a species that has rarely been implicated in disease. So, you probably need not disinfect your system if the only organisms are L. pneumophila serogroup 3 and L. gormanii. Ideally, all patients with hospital-acquired pneumonia should be cultured for Legionella. The urinary antigen will detect only L. pneumophila, serogroup 1, and cannot detect L. pneumophila, serogroup 3, or L. gormanii. If Legionella cultures are unavailable, perhaps a quinolone should be added to cases of hospital-acquired pneumonia that do not have a clear-cut etiologic diagnosis.
Two reviews of Legionella gormanii are in the Publication Sections of www.legionella.org
Fang GD. Disease due to the legionellaceae (other than L. pneumophila): historical, microbiological, clinical, and epidemiological review. Medicine 1989;68:116-132.
7 cases of L. gormanii are reviewed in this article.