Table 1. Number of residents colonised with extended-spectrum beta-lactamase-producing Escherichia coli at various study points in a long-term care facility, the Netherlands, March 2013 to April 2014 (n=296).

Organism category	Residents colonised at start of the survey (number positive during entire surveya)	Residents with colonisation acquired during study period (number with presumed in-ward transmission)	Residents colonised when admitted during the study period	Total number colonised at any point
ESBL-ST131b	24 (10)	14 (12)	3	41
Other ESBL-ECc	11 (1)	17 (10)	5	33
Total	35 (11)	29d (22)	8	69d,e

EC: Escherichia coli; ESBL: extended-spectrum beta-lactamase.

^a Only residents who remained in the facility for the entire study period could be positive during the entire survey; this in contrast to residents who were lost to follow-up.

^b ESBL-ST131: ESBL-producing E. coli isolates belonging to sequence type ST131.

^c Other ESBL-EC: ESBL-producing E. coli isolates not belonging to ST131.

^d Two residents acquired both an ESBL-ST131 and a non-ST131 ESBL-EC.

^e Three residents were positive with ESBL-ST131 at the start of the survey, and acquired a non-ST131 ESBL-EC later.