TABLE 1.
Association between Patient Characteristics and Acquisition of Extended-Spectrum β-Lactamase (ESBL)–Producing Bacteria
| Patient characteristic | Acquired ESBL-producing bacteria (n = 267) | Did not acquire ESBL-producing bacteria (n = 9,104) | P |
|---|---|---|---|
| Prior room occupant positive for ESBL-producing | |||
| Klebsiella species or Escherichia coli | 32 (4.9) | 235 (2.7) | <.01 |
| Age, mean years (± SD) | 57.1 (15.2) | 55.6 (15.6) | .11 |
| Male sex | 161 (60.3) | 5,033 (55.3) | .10 |
| Admission to the MICU | 175 (65.5) | 4,619 (50.7) | <.01 |
| ICU total length of stay, median days (IQR) | 11 (5–24) | 4 (2–8) | <.01 |
| ICU time at risk, median days (IQR) | 8 (4–15) | 4 (2–8) | <.01 |
| Prior room occupant length of stay, median days (IQR) | 3 (1–5) | 2 (1–5) | .85 |
| Colonization pressure, median value (IQR) | 0.13 (0.06–0.13) | 0.07 (0.01–0.14) | <.01 |
| Comorbidity | |||
| AIDS | 10 (3.8) | 439 (4.8) | .42 |
| Malignancy | 35 (13.1) | 1,998 (21.9) | <.01 |
| Cerebrovascular disease | 18 (6.7) | 1,170 (12.8) | <.01 |
| Chronic pulmonary disease | 49 (18.4) | 1,920 (21.1) | .28 |
| Diabetes | 47 (17.6) | 1,964 (21.6) | .12 |
| Cardiovascular disease | 68 (25.5) | 2,337 (25.7) | .94 |
| Liver disease | 29 (10.9) | 887 (9.7) | .54 |
| Renal disease | 65 (24.3) | 1,148 (12.6) | <.01 |
| Charlson comorbidity index, mean (IQR) | 2 (1–3) | 2 (1– 4) | .11 |
| ICU chronic disease score, mean (± SD) | 8.9 (3.9) | 8.6 (4.2) | .23 |
| ICU antibiotic use | |||
| Any antibiotic exposure | 259 (97.0) | 7,713 (84.2) | <.01 |
| Piperacillin-tazobactam | 158 (59.2) | 3,536 (38.8) | <.01 |
| First-generation cephalosporins | 28 (10.5) | 1,316 (14.9) | .07 |
| Second-generation cephalosporins | 6 (2.3) | 313 (3.4) | .29 |
| Third-generation cephalosporins | 23 (8.6) | 1,031 (11.2) | .17 |
| Cefepime | 52 (19.5) | 724 (7.9) | <.01 |
| Antifungal therapy | 85 (31.8) | 2,188 (20.0) | <.01 |
| A ntipseudomonal β-lactam | 232 (86.7) | 5,107 (56.1) | <.01 |
| Macrolides | 33 (12.4) | 900 (9.9) | .18 |
| Quinolones | 66 (24.7) | 1,910 (20.9) | .14 |
| Anti-MRSA therapy | 189 (70.8) | 3,447 (37.9) | <.01 |
note. Data are no. (%) of patients, unless otherwise indicated. Antimicrobial drug exposure was defined as antibiotic therapy ordered during the period between ICU admission and ICU discharge for patients who did not acquire an ESBL-producing pathogen and between ICU admission and date on which a positive culture specimen was collected for patients who acquired an ESBL-producing pathogen. Colonization pressure was defined as the daily proportion of patients positive for an ESBL-producing pathogen. For each patient, colonization pressure was calculated as the average of the daily proportion of patients positive for an ESBL-producing pathogen during their time at risk. ICU, intensive care unit; IQR, interquartile range; MICU, medical ICU; MRSA, methicillin-resistant Staphylococcus aureusr, SD, standard deviation.