Legionella pneumophila in rainwater on roads.
Bottom Line: During rain, transient puddles form on roads, and this water is splashed into the air by moving vehicles.To determine whether this water contains Legionella pneumophila, we collected samples from roads.We found that L. pneumophila are abundant in these puddles, especially during warm weather.
Affiliation: Kyoto University, Japan.
During rain, transient puddles form on roads, and this water is splashed into the air by moving vehicles. To determine whether this water contains Legionella pneumophila, we collected samples from roads. We found that L. pneumophila are abundant in these puddles, especially during warm weather.
Mentions: We took samples from puddles at 18 points as a primary survey. Simultaneously, as fixed-point observations, we set 4 points on a road and collected samples when puddles were formed. In the primary survey, L. pneumophila were detected by culture in 7 of 18 samples taken from puddles. Acanthamoeba spp. were detected by PCR in 4 of 18 puddles. L. pneumophila were not detected by culture of swab samples obtained from asphalt surfaces on sunny days, although they were detected in 2 of 12 samples tested by the LAMP method. Acanthamoeba spp. were also detected by PCR from 2 of 12 swab samples (Table). In the fixed-point observations, 16 (35.6%) of 45 puddle samples were positive by culture. According to serogroup typing of 150 strains of L. pneumophila isolated, the most prevalent serogroup was serogroup 1 (n = 56 [37.3%]) (Table). L. pneumophila were detected by culture in 3 (15.8%) of 19 samples from puddles when mean temperature was <20°C, in 6 (42.9%) of 14 samples when mean temperature was 20°C–25°C, and in 7 (58.3%) of 12 samples when mean temperature was >25°C (p = 0.043) (Figure 1). With regard to molecular typing by repetitive-element PCR, organisms of lanes 1–5 were all detected on the same day in the same puddle and identified as L. pneumophila serogroup 1. Although lanes 1–3 appeared to have different patterns, lanes 1 and 4 and lanes 3 and 5 appeared indistinguishable (Figure 2).