Table 3

Univariate and multivariate analysis of risk factors associated with intestinal colonization of imipenem-resistant Pseudomonas aeruginosa

Characteristic or outcomeNo. of individuals or parameter value (%, unless range is specified)Univariate ORaUnivariate PbMultivariate ORc
Carrier patients (n = 22 (%)Controls (n = 22)
Sociodemographic characteristics
    Age, yr [avg (range)]57.3 (30–74)60.9 (37–80)0.28
    Sex ratio (F/M)d0.570.290.31
Characteristics at admission
    Type of ICU1.00
        Surgical8 (36.4)8 (36.4)1.0
        Medical14 (63.6)14 (63.6)1.0 (0.2–4.1)
    Origin1.00
        Home6 (27.3)5 (22.7)1.0
        Hospital16 (72.7)17 (77.3)0.8 (0.2–3.8)
        Other
    Cancer1 (4.5)2 (9.1)0.5 (0.1–10.0)1.00
    HIV3 (13.6)1 (4.5)3.2 (0.2–182.0)0.61
    Respiratory failure5 (22.7)2 (9.1)2.9 (0.4–33.8)0.41
    Renal failure3 (13.6)1 (4.5)3.2 (0.2–182.0)0.61
    Cardiac failure2 (9.1)3 (13.6)0.6 (0.1–6.2)1.00
    Obesity4 (18.2)5 (22.7)0.8 (0.1–4.2)1.00
    Pulmonary transplantation
    Diabetes mellitus2 (9.1)4 (18.2)0.5 (0.1–3.6)0.66
    Cirrhosis1 (4.5)1 (4.5)1.0 (0.1–82.1)1.00
    McCabe scores0.12
        05 (22.7)11 (50.0)1.01.0
        ≥117 (77.3)11 (50.0)3.3 (0.8–15.8)5.0 (1.1–29.0)
    SAPS II (median [range])55 (15–120)41 (13–86)0.05
ESBL carriage3 (13.6)5 (22.7)0.5 (0.1–3.3)0.70
Surveillance period,e days [median (range)]13 (4–37)13 (3–37)0.91
Antibiotic treatments
    Exposure time to antibiotics, days [median (range)]10.5 (2–23)8.5 (0–37)0.52
    Penicillin exposure6 (27.3)8 (36.4)0.7 (0.1–2.8)0.75
    Penicillin and β-lactamase inhibitor exposure8 (36.4)12 (54.5)0.5 (0.1–1.9)0.36
    Cephalosporin exposure13 (59.1)12 (54.5)1.2 (0.3–4.7)1.00
    Imipenem exposure17 (77.3)10 (45.5)3.9 (0.9–18.9)0.06
    Days of imipenem exposure0.09
        05 (22.7)12 (54.5)1.01.0
        1 to 38 (36.4)6 (27.3)3.1 (0.6–18.3)5.3 (1.0–38.4)
        4 to 219 (40.9)4 (18.2)5.1 (0.9–35.1)6.8 (1.2–50.2)
    Fluoroquinolone exposure6 (27.3)4 (18.2)1.7 (0.3–9.6)0.72
    Aminoglycoside exposure14 (63.6)12 (54.5)1.4 (0.4–5.8)0.76
    Glycopeptide exposure12 (54.5)5 (22.7)3.9 (0.9–18.9)0.06
    Metronidazole exposure4 (18.2)3 (13.6)1.4 (0.2–10.9)1.00
    Macrolide exposure2 (9.1)1 (4.5)2.1 (0.1–129.6)1.00
    Colistin exposure4 (18.2)2 (9.1)2.2 (0.3–26.9)0.66
Outcome
    ICU stay, days [median (range)]27.5 (9–173)15.0 (5–137)0.25
    Death11 (50.0)7 (31.8)2.1 (0.5–8.8)0.36
  • a ORs are given with the 95% confidence intervals in parentheses.

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

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

  • d F, female; M, male.

  • e Period of surveillance, period between admission and acquisition of imipenem-resistant P. aeruginosa.