Table 3.

Summarization of environmental screening data according to acquisition group

	P. aeruginosa acquisition (n = 20)	No P. aeruginosa acquisition (n = 106)	Total (n = 126)
Cumulative patient-induced environmental pressure*
From the same ward	1.2 (0.6 to 1.8)	0.8 (0 to 1.7)	1 (0.1 to 1.8)
From the ICU	4.8 (3.6 to 5.6)	4.7 (3.3 to 5.6)	4.7 (3.3 to 5.6)
Cumulative tap water-induced environmental pressure*
From the patients' wards	0.1 (0 to 0.7)	0 (0 to 0.6)	0 (0 to 0.6)
From the ICU	1.9 (1.1 to 2.3)	1.6 (0 to 3)	1.8 (0 to 2.9)
From shared rooms	1 (0.7 to 2.3)	0.8 (0 to 1)	1 (0 to 1)
Patient-induced environmental pressure**
≥1 colonized patient on the same ward
yes	20	79	99
no	0	27	27
≥1 colonized patient on the ICU
yes	20	106	126
no	0	0	0
Tap water-induced environmental pressure**
≥1 colonized tap water on the same ward
yes	10	51	61
no	10	55	65
≥1 colonized tap water on the ICU ¤
yes	18	68	86
no	2	38	40
≥1 colonized tap water in shared rooms
yes	17	70	87
no	3	36	39

Values shown are: median (1^st to 3^rd quartile), or n.

*Cumulative patient/tap water-induced environmental pressure represents the number of contaminated patients/tap water samples since admission.

**Patient/tap water-induced environmental pressure represents the number of patient that were exposed to a contaminated patient/tap water at least one time during their ICU stay.

^¤ Excluding tap water in shared rooms.