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Table 2 Association of physical, chemical, and microbiological water characteristics with Legionella spp. concentration of hot and cold water samples on ferries water distribution systems

From: Legionella species colonization of water distribution systems, pools and air conditioning systems in cruise ships and ferries

  No of positive samples for Legionellaspp.
  Water characteristics
Legionella spp. pH     Sample Temp    
  pH ≥7.8 (%) pH <7.8 (%) RR P ≥ 55°C (%) < 55°C (%) RR P
Legionella spp. 32 (32.0) 40 (27.2) 1.17 0.25 7 (14.9) 74 (35.7) 0.41 0. 003
L. pneumophila sg 1 17 (17.0) 25 (17.0) 0.99 0.5 2 (4.3) 40 (19.3) 0.22 0.006
L. pneumophila sg 2–14 22 (22.0) 14 (9.5) 2.30 0.005 3 (6.4) 41 (19.8) 0.32 0.01
Legionella non pneumophila 1 (1.0) 7 (4.8) 0.21 0.09 2 (4.3) 7 (3.4) 1.25 0.5
  Free chlorine Total plate count
  ≥ 0.2 mg/L (%) < 0.2 mg/L (%) RR P ≥400 CFU/L (%) <400 CFU/L (%) RR P
Legionella spp. 8 (12.5) 10 (34.5) 0.36 0.01 26 (53.1) 56 (25.7) 2.09 0.0002
L. pneumophila sg 1 6 (9.4) 6 (20.7) 0.45 0.1 13 (26.5) 30 (13.8) 1.92 0.02
L. pneumophila sg 2–14 2 (3.1) 4 (13.8) 0.22 0.07 13 (26.9) 31 (14.2) 1.86 0.03
Legionella non pneumophila 0 (0.0) 2 (6.9) 0.00 0.09 3 (6.1) 6 (2.8) 2.22 0.2