Table 2

Univariate and multivariate analysis of risk factors associated with intestinal colonization of imipenem-resistant Gram-negative bacillia

Characteristic or outcomeNo. of individuals or parameter value (%, unless range is specified)Univariate ORbUnivariate PcMultivariate ORd
Carrier patients (n = 36)Controls (n = 36)
Sociodemographic characteristics
    Age, yr [avg (range)]58.3 (30–86)59.9 (37–86)0.57
    Sex ratio (F/M)e0.330.640.31
Characteristics at admission
    Type of ICU1.00
        Surgical14 (38.9)14 (38.9)1.0
        Medical22 (61.1)22 (61.1)1.0 (0.3–2.9)
    Origin0.69
        Home8 (22.2)10 (27.8)1.0
        Hospital27 (75.0)24 (66.7)1.4 (0.4–4.8)
        Other1 (2.8)2 (5.6)0.6 (0.1–14.4)
    Cancer2 (5.6)2 (5.6)1.0 (0.1–14.5)1.00
    HIV3 (8.3)4 (11.1)0.7 (0.1–4.7)1.00
    Respiratory failure7 (19.4)3 (8.3)2.6 (0.5–17.2)0.31
    Renal failure6 (16.7)1 (2.8)6.8 (0.8–330.4)0.11
    Cardiac failure3 (8.3)4 (11.1)0.7 (0.1–4.7)1.00
    Obesity6 (16.7)6 (16.7)1.0 (0.2–4.2)1.00
    Pulmonary transplantation3 (8.3)2 (5.6)1.5 (0.2–19.5)1.00
    Diabetes mellitus4 (11.1)5 (13.9)0.8 (0.1–4.0)1.00
    Cirrhosis2 (5.6)2 (5.6)1.0 (0.1–14.5)1.00
    McCabe scores0.07
        07 (19.4)15 (41.7)1.0
        ≥129 (80.6)21 (58.3)2.9 (0.9–10.0)
    SAPS II [median (range)]48.5 (13–120)41 (13–104)0.36
ESBL carriage8 (22.2)6 (16.7)1.4 (0.4–5.7)0.77
Surveillance period,f days [median (range)]13.5 (3–52)12.5 (3–52)0.97
Antibiotic treatments
    Exposure time to antibiotics, days [median (range)]11.5 (0–51)9.0 (0–37)0.84
    Penicillin exposure8 (22.2)16 (44.4)0.4 (0.1–1.1)0.080.3 (0.1–0.8)
    Penicillin and β-lactamase inhibitor exposure17 (47.2)20 (55.6)0.7 (0.3–2.0)0.64
    Cephalosporin exposure20 (55.6)17 (47.2)1.4 (0.5–3.9)0.64
    Imipenem exposure28 (77.8)14 (38.9)5.4 (1.8–17.8)<0.01
    Days of imipenem exposure<0.01
        08 (22.2)22 (61.1)1.01.0
        1 to 310 (27.8)6 (16.7)4.4 (1.1–20.5)5.9 (1.5–25.7)
        4 to 2118 (50.0)8 (22.2)6.0 (1.7–23.3)7.8 (2.4–29.8)
    Fluoroquinolone exposure9 (25.0)8 (22.2)1.2 (0.3–4.0)1.00
    Aminoglycoside exposure25 (69.4)21 (58.3)1.6 (0.6–4.8)0.46
    Glycopeptide exposure20 (55.6)11 (30.6)2.8 (1.0–8.4)0.06
    Metronidazole exposure5 (13.9)6 (16.7)0.8 (0.2–3.6)1.00
    Macrolide exposure5 (13.9)3 (8.3)1.8 (0.3–12.3)0.71
    Colistin exposure5 (13.9)2 (5.6)2.7 (0.4–30.4)0.43
Outcome
    ICU stay, days [median (range)]33.5 (4–173)15.5 (5–137)0.14
    Death13 (36.1)11 (30.6)1.3 (0.4–3.9)0.80
  • a Imipenem-resistant Gram-negative bacilli including Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Enterobacteriaceae, and Acinetobacter baumannii.

  • b Odds ratios (ORs) are given with the 95% confidence intervals in parentheses.

  • c Bivariate analysis was performed using Pearson's chi-squared, Fisher's exact, Wilcoxon, or Welch test (α = 0.05).

  • d Variables with univariate P value of <0.15 were included for multivariate analysis, which was performed using descending stepwise logistic regression.

  • e F, female; M, male.

  • f Period of surveillance, period between admission and acquisition of imipenem-resistant Gram-negative bacilli.