Clinical impact and risk factors for colonization with extended-spectrum β-lactamase-producing bacteria in the intensive care unit

The changed epidemiology of extended spectrum beta-lactamases (ESBL), the spread to the community and the need for prudent use of carbapenems require updated knowledge of risk factors for colonization with ESBL-producing enterobacteriaceae (ESBL-PE).

An 8-month prospective study in the medical ICU of an 850-bed general and university-affiliated hospital.

Of 610 patients admitted, 531 (87 %) had a rectal swab obtained at admission, showing a 15 % (82 patients) ESBL-PE carriage rate, mostly of E. coli (n = 51, 62 %); ESBL-PE caused 9 (3 %) infections on admission. By multivariable analysis, transfer from another ICU (OR = 2.56 [1, 22]), hospital admission in another country [OR = 5.28 (1.56-17.8)], surgery within the past year [OR = 2.28 (1.34-3.86)], prior neurologic disease [OR = 2.09 (1.1-4.0)], and prior administration of third generation cephalosporin (within 3-12 months before ICU admission) [OR = 3.05 (1.21-7.68)] were independent predictive factors of colonization by ESBL-PE upon ICU admission. Twenty-eight patients (13 % of those staying for more than 5 days) acquired ESBL carriage in ICU, mostly with E. cloacae (n = 13, 46 %) and K. pneumoniae (n = 10, 36 %). In carriers, ESBL-PE caused 10 and 27 % of first and second episodes of ICU-acquired infections, respectively.

We found a high prevalence of ESBLE-PE colonization on admission to our ICU, even in the subgroup admitted from the community, but few first infections. Identifying risk factors for ESBL-PE colonization may help identifying which patients may warrant empiric ESBL-targeted antimicrobial drug therapy as a means to limit carbapenem use.