Long-term use of selective digestive decontamination in an ICU highly endemic for bacterial resistance

Table 6 Evolution of rates of resistance to colistin and tobramycin in ICU, by 1000 days

	Resistance	Period
		1st year	2nd year	3rd year	4th year
		(n = 59)	(n = 56)	(n = 69)	(n = 101)
Patient-days		9228	8583	10,731	9315
Colistin	At admission	5 (8.5)	17 (30.4)	30 (43.5)	61 (60.4)
	Acquired in ICU	3 (5.1)	8 (14.3)	7 (10.1)	12 (11.9)
	Acquired in ICU, by 1000 days	0.325	0.932	0.652	1.288
	Acquired in ICU, by 1000 days and adjusted by rate of resistance at admission^a	0.278	0.228	0.187	0.153
Tobramycin	At admission	17 (6.0)	32 (11.2)	34 (11.9)	68 (23.9)
	Acquired in ICU	1 (0.4)	3 (1.1)	15 (5.3)	11 (3.9)
	Acquired in ICU, by 1000 days	0.108	0.350	1.398	1.181
	Acquired in ICU, by 1000 days and adjusted by rate of resistance at admission^a	0.144	0.162	0.182	0.205

ICU Intensive care unit
The increasing rate of colistin- and tobramycin-acquired colonization resistance in the ICU by 1000 days and adjusted by the rate of resistance at admission was 0.82 (95% CI, 0.56 to 1.95; not statistically significant [NS]). P value for the goodness-of-fit test was 0.427. For tobramycin, the increasing rate was 1.13 (95% CI, 0.75 to 1.70; nonsignificant). P value for the goodness-of-fit test was 0.159
^aAdjusted for values corresponding to first year, namely number of patients, number of resistances at admission, and exposure days

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