Legionella in clinical specimens and hospital water supply facilities: molecular detection and genotyping of the isolates

ABSTRACT

To evaluate genus- and species-specific polymerase chain reactions [PCRs] for the detection of the genus Legionella and the species Legionella pneumophila in clinical specimens and hospital water supplies, and to establish a simple and reproducible random amplification of polymorphic DNA [RAPD]-PCR technique for genotyping of Legionella. A total of 70 respiratory tract specimens [bronchoalveolar lavage n = 46; endotracheal secretions n = 9; sputum n = 15] from patients with atypical pneumonia, and 283 environmental samples [water 20; swabs 263] collected from water storage and supply facilities of the Mubarak Al-Kabeer Hospital, Kuwait, were tested by culture and genus-specific PCR for the detection of Legionella. The L pneumophila isolates were subsequently typed by serology and RAPD-PCR using serotype-specific sera and arbitrary primers, respectively. Of the 70 clinical samples, culture yielded 2 [2.9%] whereas genus-specific PCR detected Legionella in 20 [28.6%] samples. The 2 culture-positive specimens were also positive for L.-pneumophila-specific PCR. Testing of swab and water samples by culture and genus-specific PCR yielded 61 [21.6%] and 67 [23.7%] positive samples, respectively. All of the 61 culture-positive samples were also positive by genus-specific PCR and 45 of them were positive for L.-pneumophila-specific PCR. Serological typing of 43 L pneumophila isolates showed that 8 of these belonged to serotype 1 and 35 to serotype 3; however, RAPD-PCR analyses demonstrated polymorphisms among the isolates of both serotypes. A higher association between PCR and culture was observed for the environmental samples than for the clinical samples. The application of genus- and species-specific PCRs and RAPD is useful in the detection and typing of Legionella in clinical and environmental samples