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. 2014 Jul 16;14:394. doi: 10.1186/1471-2334-14-394

Table 4.

Risk factors associated with Legionella isolation in univariate analysis

Risk factors
 Parameters
 Legionella isolation no. (%)
  
    Yes No OR 95% CI p-value
Water temperature°C
 ≥20°C - ≤ 45°C
 48 (13.3)
 314 (86.7)
 1.98
 1.30 - 3.03
 < 0.001
vs.
 <20°C or > 45°C
 47 (7.2)
 609 (92.8)
Residual free chlorine concentration mg/L
 < 0.5
 90 (12.9)
 610 (87.1)
 5.3
 2.63 - 10.65
 < 0.001
vs.
 ≥ 0.5
 9 (2.7)
 323 (97.3)
Potability of water according to regulation
 Not potable water
 9 (25.0)
 27 (75.0)
 4.48
 1.87 - 10.74
 0.001
vs.
 Potable water
 21 (6.9)
 282 (93.1)
No continuous vs. continuous hyperchlorination
 No continuous hyperchlorination
 15 (27.3)
 40 (72.7)
 6.41
 3.10 - 13.26
 < 0.001
vs.
 Continuous hyperchlorination
 23 (5.5)
 393 (94.5)
Before vs. shock hyperchlorination at 15 days
 Before shock hyperchlorination
 43 (21.1)
 161 (78.9)
 3.17
 1.70 - 5.92
 < 0.001
vs.
 Shock hyperchlorination at 15 days
 15 (7.8)
 178 (92.2)
Before vs. shock hyperchlorination at 30 days
 Before shock hyperchlorination
 43 (21.1)
 161 (78.9)
 7.43
 3.08 - 17.94
 < 0.001
vs.
 Shock hyperchlorination at 30 days
 6 (3.5)
 167 (96.5)
Before vs. continuous hyperchlorination
 Before shock hyperchlorination
 43 (21.1)
 161 (78.9)
 4.56
 2.66 - 7.82
 < 0.001
vs.
 Continuous hyperchlorination
 23 (5.5)
 393 (94.5)
Continuous vs. shock hyperchlorination at 30 days
 Continuous hyperchlorination
 23 (5.5)
 393 (94.5)
 1.63
 0.65 - 4.07
 0.15
vs. Shock hyperchlorination at 30 days 6 (3.5) 167 (96.5)