Table 1. Open in new tab...

Variable

All patients, n = 287

Low MIC (≤4 mg/L), n = 248

Borderline MIC (8–16 mg/L), n = 27

P^a

High MIC (≥32 mg/L), n = 12

Age (years), median (IQR)

73 (64–80)

73 (64–81)

69 (60–83)

0.53

68 (65–77)

Male

188 (65.5)

160 (64.5)

19 (70.4)

0.55

9 (75.0)

Hospital-acquired infection

178 (62.0)

146 (58.9)

21 (77.8)

0.05

11 (91.7)

Comorbidities

diabetes mellitus

88 (30.7)

80 (32.3)

5 (18.5)

0.14

3 (25)

chronic pulmonary disease

36 (12.5)

32 (12.9)

3 (11.1)

1 (8.3)

congestive heart failure

17 (5.9)

14 (5.6)

2 (7.4)

0.66

1 (8.3)

malignancy

83 (28.9)

72 (29.0)

9 (33.3)

0.64

2 (16.7)

renal failure (end-stage renal disease)

24 (8.4)

22 (8.9)

2 (7.4)

0 (0)

liver cirrhosis

8 (2.8)

6 (2.4)

1 (3.7)

0.52

1 (8.3)

immunocompromised

22 (7.6)

22 (8.9)

0 (0)

0.14

0 (0)

ultimately or rapidly fatal disease (McCabe classification)

103 (35.9)

92 (37.1)

10 (37.0)

0.99

1 (8.3)

age-weighted Charlson comorbidity index, median (IQR)

2 (0–3)

0.8

1 (0–2)

Pitt score, median (IQR)

1 (0–2)

0 (0–2)

0.28

1.5 (0–2)

Invasive procedures

mechanical ventilation

10 (3.5)

9 (3.6)

0 (0)

0.61

1 (8.3)

major surgery

41 (14.3)

36 (14.5)

3 (11.1)

0.78

2 (16.7)

severe sepsis or septic shock

95 (33.1)

84 (34.0)

8 (29.6)

0.65

3 (25.0)

Source of bacteraemia

urinary tract

74 (25.8)

65 (26.2)

6 (22.2)

0.65

3 (25.0)

biliary tract

138 (48.1)

119 (48.0)

14 (51.9)

0.7

5 (41.7)

intra-abdominal

30 (10.5)

25 (10.1)

2 (7.4)

3 (25.0)

vascular catheter

12 (4.2)

9 (3.6)

3 (11.1)

0.1

0 (0)

respiratory tract

16 (5.6)

15 (6.0)

0 (0)

0.38

1 (8.3)

others

17 (5.8)

15 (6.0)

2 (7.4)

0.68

0 (0)

Aetiology

Escherichia coli

183 (63.8)

160 (64.5)

14 (51.9)

0.19

9 (75.0)

Klebsiella pneumoniae

49 (17.1)

43 (17.3)

4 (14.8)

2 (16.7)

Klebsiella oxytoca

8 (2.8)

7 (2.8)

1 (3.7)

0.57

0 (0)

Enterobacter cloacae

17 (5.9)

14 (5.6)

3 (11.1)

0.23

0 (0)

Enterobacter aerogenes

8 (2.8)

5 (2.0)

2 (7.4)

0.14

1 (8.3)

Citrobacter freundii

3 (1.0)

2 (0.8)

1 (3.7)

0.27

0 (0)

Proteus mirabilis

4 (1.4)

4 (1.6)

0 (0)

Morganella morganii

3 (1.0)

3 (1.2)

0 (0)

Serratia marcescens

12 (4.2)

10 (4.0)

2 (7.4)

0.33

0 (0)

ESBL producer

14 (4.9)

11 (4.4)

2 (7.4)

0.37

1 (8.3)

Piperacillin/tazobactam dose

4.5 g/8 h bolus

174 (60.6)

149 (60.1)

16 (59.3)

0.93

9 (75.0)

4.5 g/8 h extended infusion

51 (17.8)

42 (16.9)

6 (22.2)

0.59

3 (25.0)

others

62 (21.6)

57 (23.0)

5 (18.5)

0.59

0 (0)

fT_>MIC

(n = 251)

(n = 220)

(n = 21)

(n = 10)

50% fT_>MIC

242 (96.4)

219 (99.5)

18 (87.5)

0.002

5 (50.0)

100% fT_>MIC

196 (78.1)

189 (85.9)

7 (33.3)

<0.0001

0 (0)

Outcome at day 21

clinical cure

227 (79.1)

200 (80.6)

19 (70.4)

0.21

8 (66.7)

improvement

34 (11.8)

26 (10.5)

6 (22.2)

0.11

2 (16.7)

failure

26 (9.1)

22 (8.9)

2 (7.4)

2 (16.7)

Outcome at the end of treatment with piperacillin/tazobactam

clinical cure

57 (19.9)

47 (19.0)

7 (25.9)

0.39

3 (25.0)

improvement

185 (64.5)

162 (65.3)

18 (66.7)

0.89

5 (41.7)

failure

45 (15.7)

39 (15.7)

2 (7.4)

0.39

4 (3.3)

Mortality at day 30

31 (10.8)

26 (10.5)

3 (11.1)

2 (16.7)

Variable

All patients, n = 287

Low MIC (≤4 mg/L), n = 248

Borderline MIC (8–16 mg/L), n = 27

P^a

High MIC (≥32 mg/L), n = 12

Age (years), median (IQR)

73 (64–80)

73 (64–81)

69 (60–83)

0.53

68 (65–77)

Male

188 (65.5)

160 (64.5)

19 (70.4)

0.55

9 (75.0)

Hospital-acquired infection

178 (62.0)

146 (58.9)

21 (77.8)

0.05

11 (91.7)

Comorbidities

diabetes mellitus

88 (30.7)

80 (32.3)

5 (18.5)

0.14

3 (25)

chronic pulmonary disease

36 (12.5)

32 (12.9)

3 (11.1)

1 (8.3)

congestive heart failure

17 (5.9)

14 (5.6)

2 (7.4)

0.66

1 (8.3)

malignancy

83 (28.9)

72 (29.0)

9 (33.3)

0.64

2 (16.7)

renal failure (end-stage renal disease)

24 (8.4)

22 (8.9)

2 (7.4)

0 (0)

liver cirrhosis

8 (2.8)

6 (2.4)

1 (3.7)

0.52

1 (8.3)

immunocompromised

22 (7.6)

22 (8.9)

0 (0)

0.14

0 (0)

ultimately or rapidly fatal disease (McCabe classification)

103 (35.9)

92 (37.1)

10 (37.0)

0.99

1 (8.3)

age-weighted Charlson comorbidity index, median (IQR)

2 (0–3)

0.8

1 (0–2)

Pitt score, median (IQR)

1 (0–2)

0 (0–2)

0.28

1.5 (0–2)

Invasive procedures

mechanical ventilation

10 (3.5)

9 (3.6)

0 (0)

0.61

1 (8.3)

major surgery

41 (14.3)

36 (14.5)

3 (11.1)

0.78

2 (16.7)

severe sepsis or septic shock

95 (33.1)

84 (34.0)

8 (29.6)

0.65

3 (25.0)

Source of bacteraemia

urinary tract

74 (25.8)

65 (26.2)

6 (22.2)

0.65

3 (25.0)

biliary tract

138 (48.1)

119 (48.0)

14 (51.9)

0.7

5 (41.7)

intra-abdominal

30 (10.5)

25 (10.1)

2 (7.4)

3 (25.0)

vascular catheter

12 (4.2)

9 (3.6)

3 (11.1)

0.1

0 (0)

respiratory tract

16 (5.6)

15 (6.0)

0 (0)

0.38

1 (8.3)

others

17 (5.8)

15 (6.0)

2 (7.4)

0.68

0 (0)

Aetiology

Escherichia coli

183 (63.8)

160 (64.5)

14 (51.9)

0.19

9 (75.0)

Klebsiella pneumoniae

49 (17.1)

43 (17.3)

4 (14.8)

2 (16.7)

Klebsiella oxytoca

8 (2.8)

7 (2.8)

1 (3.7)

0.57

0 (0)

Enterobacter cloacae

17 (5.9)

14 (5.6)

3 (11.1)

0.23

0 (0)

Enterobacter aerogenes

8 (2.8)

5 (2.0)

2 (7.4)

0.14

1 (8.3)

Citrobacter freundii

3 (1.0)

2 (0.8)

1 (3.7)

0.27

0 (0)

Proteus mirabilis

4 (1.4)

4 (1.6)

0 (0)

Morganella morganii

3 (1.0)

3 (1.2)

0 (0)

Serratia marcescens

12 (4.2)

10 (4.0)

2 (7.4)

0.33

0 (0)

ESBL producer

14 (4.9)

11 (4.4)

2 (7.4)

0.37

1 (8.3)

Piperacillin/tazobactam dose

4.5 g/8 h bolus

174 (60.6)

149 (60.1)

16 (59.3)

0.93

9 (75.0)

4.5 g/8 h extended infusion

51 (17.8)

42 (16.9)

6 (22.2)

0.59

3 (25.0)

others

62 (21.6)

57 (23.0)

5 (18.5)

0.59

0 (0)

fT_>MIC

(n = 251)

(n = 220)

(n = 21)

(n = 10)

50% fT_>MIC

242 (96.4)

219 (99.5)

18 (87.5)

0.002

5 (50.0)

100% fT_>MIC

196 (78.1)

189 (85.9)

7 (33.3)

<0.0001

0 (0)

Outcome at day 21

clinical cure

227 (79.1)

200 (80.6)

19 (70.4)

0.21

8 (66.7)

improvement

34 (11.8)

26 (10.5)

6 (22.2)

0.11

2 (16.7)

failure

26 (9.1)

22 (8.9)

2 (7.4)

2 (16.7)

Outcome at the end of treatment with piperacillin/tazobactam

clinical cure

57 (19.9)

47 (19.0)

7 (25.9)

0.39

3 (25.0)

improvement

185 (64.5)

162 (65.3)

18 (66.7)

0.89

5 (41.7)

failure

45 (15.7)

39 (15.7)

2 (7.4)

0.39

4 (3.3)

Mortality at day 30

31 (10.8)

26 (10.5)

3 (11.1)

2 (16.7)

Table 1.

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Characteristics, clinical features and outcomes of patients with bloodstream infections caused by Enterobacteriaceae treated with piperacillin/tazobactam; data are expressed as number of patients (%) except where specified

Variable	All patients, n = 287	Low MIC (≤4 mg/L), n = 248	Borderline MIC (8–16 mg/L), n = 27	P^a	High MIC (≥32 mg/L), n = 12
Age (years), median (IQR)	73 (64–80)	73 (64–81)	69 (60–83)	0.53	68 (65–77)
Male	188 (65.5)	160 (64.5)	19 (70.4)	0.55	9 (75.0)
Hospital-acquired infection	178 (62.0)	146 (58.9)	21 (77.8)	0.05	11 (91.7)
Comorbidities
diabetes mellitus	88 (30.7)	80 (32.3)	5 (18.5)	0.14	3 (25)
chronic pulmonary disease	36 (12.5)	32 (12.9)	3 (11.1)	1	1 (8.3)
congestive heart failure	17 (5.9)	14 (5.6)	2 (7.4)	0.66	1 (8.3)
malignancy	83 (28.9)	72 (29.0)	9 (33.3)	0.64	2 (16.7)
renal failure (end-stage renal disease)	24 (8.4)	22 (8.9)	2 (7.4)	1	0 (0)
liver cirrhosis	8 (2.8)	6 (2.4)	1 (3.7)	0.52	1 (8.3)
immunocompromised	22 (7.6)	22 (8.9)	0 (0)	0.14	0 (0)
ultimately or rapidly fatal disease (McCabe classification)	103 (35.9)	92 (37.1)	10 (37.0)	0.99	1 (8.3)
age-weighted Charlson comorbidity index, median (IQR)	2 (0–3)	2 (0–3)	2 (0–3)	0.8	1 (0–2)
Pitt score, median (IQR)	1 (0–2)	1 (0–2)	0 (0–2)	0.28	1.5 (0–2)
Invasive procedures
mechanical ventilation	10 (3.5)	9 (3.6)	0 (0)	0.61	1 (8.3)
major surgery	41 (14.3)	36 (14.5)	3 (11.1)	0.78	2 (16.7)
severe sepsis or septic shock	95 (33.1)	84 (34.0)	8 (29.6)	0.65	3 (25.0)
Source of bacteraemia
urinary tract	74 (25.8)	65 (26.2)	6 (22.2)	0.65	3 (25.0)
biliary tract	138 (48.1)	119 (48.0)	14 (51.9)	0.7	5 (41.7)
intra-abdominal	30 (10.5)	25 (10.1)	2 (7.4)	1	3 (25.0)
vascular catheter	12 (4.2)	9 (3.6)	3 (11.1)	0.1	0 (0)
respiratory tract	16 (5.6)	15 (6.0)	0 (0)	0.38	1 (8.3)
others	17 (5.8)	15 (6.0)	2 (7.4)	0.68	0 (0)
Aetiology
Escherichia coli	183 (63.8)	160 (64.5)	14 (51.9)	0.19	9 (75.0)
Klebsiella pneumoniae	49 (17.1)	43 (17.3)	4 (14.8)	1	2 (16.7)
Klebsiella oxytoca	8 (2.8)	7 (2.8)	1 (3.7)	0.57	0 (0)
Enterobacter cloacae	17 (5.9)	14 (5.6)	3 (11.1)	0.23	0 (0)
Enterobacter aerogenes	8 (2.8)	5 (2.0)	2 (7.4)	0.14	1 (8.3)
Citrobacter freundii	3 (1.0)	2 (0.8)	1 (3.7)	0.27	0 (0)
Proteus mirabilis	4 (1.4)	4 (1.6)	0 (0)	1	0 (0)
Morganella morganii	3 (1.0)	3 (1.2)	0 (0)	1	0 (0)
Serratia marcescens	12 (4.2)	10 (4.0)	2 (7.4)	0.33	0 (0)
ESBL producer	14 (4.9)	11 (4.4)	2 (7.4)	0.37	1 (8.3)
Piperacillin/tazobactam dose
4.5 g/8 h bolus	174 (60.6)	149 (60.1)	16 (59.3)	0.93	9 (75.0)
4.5 g/8 h extended infusion	51 (17.8)	42 (16.9)	6 (22.2)	0.59	3 (25.0)
others	62 (21.6)	57 (23.0)	5 (18.5)	0.59	0 (0)
fT_>MIC	(n = 251)	(n = 220)	(n = 21)		(n = 10)
50% fT_>MIC	242 (96.4)	219 (99.5)	18 (87.5)	0.002	5 (50.0)
100% fT_>MIC	196 (78.1)	189 (85.9)	7 (33.3)	<0.0001	0 (0)
Outcome at day 21
clinical cure	227 (79.1)	200 (80.6)	19 (70.4)	0.21	8 (66.7)
improvement	34 (11.8)	26 (10.5)	6 (22.2)	0.11	2 (16.7)
failure	26 (9.1)	22 (8.9)	2 (7.4)	1	2 (16.7)
Outcome at the end of treatment with piperacillin/tazobactam
clinical cure	57 (19.9)	47 (19.0)	7 (25.9)	0.39	3 (25.0)
improvement	185 (64.5)	162 (65.3)	18 (66.7)	0.89	5 (41.7)
failure	45 (15.7)	39 (15.7)	2 (7.4)	0.39	4 (3.3)
Mortality at day 30	31 (10.8)	26 (10.5)	3 (11.1)	1	2 (16.7)

Variable	All patients, n = 287	Low MIC (≤4 mg/L), n = 248	Borderline MIC (8–16 mg/L), n = 27	P^a	High MIC (≥32 mg/L), n = 12
Age (years), median (IQR)	73 (64–80)	73 (64–81)	69 (60–83)	0.53	68 (65–77)
Male	188 (65.5)	160 (64.5)	19 (70.4)	0.55	9 (75.0)
Hospital-acquired infection	178 (62.0)	146 (58.9)	21 (77.8)	0.05	11 (91.7)
Comorbidities
diabetes mellitus	88 (30.7)	80 (32.3)	5 (18.5)	0.14	3 (25)
chronic pulmonary disease	36 (12.5)	32 (12.9)	3 (11.1)	1	1 (8.3)
congestive heart failure	17 (5.9)	14 (5.6)	2 (7.4)	0.66	1 (8.3)
malignancy	83 (28.9)	72 (29.0)	9 (33.3)	0.64	2 (16.7)
renal failure (end-stage renal disease)	24 (8.4)	22 (8.9)	2 (7.4)	1	0 (0)
liver cirrhosis	8 (2.8)	6 (2.4)	1 (3.7)	0.52	1 (8.3)
immunocompromised	22 (7.6)	22 (8.9)	0 (0)	0.14	0 (0)
ultimately or rapidly fatal disease (McCabe classification)	103 (35.9)	92 (37.1)	10 (37.0)	0.99	1 (8.3)
age-weighted Charlson comorbidity index, median (IQR)	2 (0–3)	2 (0–3)	2 (0–3)	0.8	1 (0–2)
Pitt score, median (IQR)	1 (0–2)	1 (0–2)	0 (0–2)	0.28	1.5 (0–2)
Invasive procedures
mechanical ventilation	10 (3.5)	9 (3.6)	0 (0)	0.61	1 (8.3)
major surgery	41 (14.3)	36 (14.5)	3 (11.1)	0.78	2 (16.7)
severe sepsis or septic shock	95 (33.1)	84 (34.0)	8 (29.6)	0.65	3 (25.0)
Source of bacteraemia
urinary tract	74 (25.8)	65 (26.2)	6 (22.2)	0.65	3 (25.0)
biliary tract	138 (48.1)	119 (48.0)	14 (51.9)	0.7	5 (41.7)
intra-abdominal	30 (10.5)	25 (10.1)	2 (7.4)	1	3 (25.0)
vascular catheter	12 (4.2)	9 (3.6)	3 (11.1)	0.1	0 (0)
respiratory tract	16 (5.6)	15 (6.0)	0 (0)	0.38	1 (8.3)
others	17 (5.8)	15 (6.0)	2 (7.4)	0.68	0 (0)
Aetiology
Escherichia coli	183 (63.8)	160 (64.5)	14 (51.9)	0.19	9 (75.0)
Klebsiella pneumoniae	49 (17.1)	43 (17.3)	4 (14.8)	1	2 (16.7)
Klebsiella oxytoca	8 (2.8)	7 (2.8)	1 (3.7)	0.57	0 (0)
Enterobacter cloacae	17 (5.9)	14 (5.6)	3 (11.1)	0.23	0 (0)
Enterobacter aerogenes	8 (2.8)	5 (2.0)	2 (7.4)	0.14	1 (8.3)
Citrobacter freundii	3 (1.0)	2 (0.8)	1 (3.7)	0.27	0 (0)
Proteus mirabilis	4 (1.4)	4 (1.6)	0 (0)	1	0 (0)
Morganella morganii	3 (1.0)	3 (1.2)	0 (0)	1	0 (0)
Serratia marcescens	12 (4.2)	10 (4.0)	2 (7.4)	0.33	0 (0)
ESBL producer	14 (4.9)	11 (4.4)	2 (7.4)	0.37	1 (8.3)
Piperacillin/tazobactam dose
4.5 g/8 h bolus	174 (60.6)	149 (60.1)	16 (59.3)	0.93	9 (75.0)
4.5 g/8 h extended infusion	51 (17.8)	42 (16.9)	6 (22.2)	0.59	3 (25.0)
others	62 (21.6)	57 (23.0)	5 (18.5)	0.59	0 (0)
fT_>MIC	(n = 251)	(n = 220)	(n = 21)		(n = 10)
50% fT_>MIC	242 (96.4)	219 (99.5)	18 (87.5)	0.002	5 (50.0)
100% fT_>MIC	196 (78.1)	189 (85.9)	7 (33.3)	<0.0001	0 (0)
Outcome at day 21
clinical cure	227 (79.1)	200 (80.6)	19 (70.4)	0.21	8 (66.7)
improvement	34 (11.8)	26 (10.5)	6 (22.2)	0.11	2 (16.7)
failure	26 (9.1)	22 (8.9)	2 (7.4)	1	2 (16.7)
Outcome at the end of treatment with piperacillin/tazobactam
clinical cure	57 (19.9)	47 (19.0)	7 (25.9)	0.39	3 (25.0)
improvement	185 (64.5)	162 (65.3)	18 (66.7)	0.89	5 (41.7)
failure	45 (15.7)	39 (15.7)	2 (7.4)	0.39	4 (3.3)
Mortality at day 30	31 (10.8)	26 (10.5)	3 (11.1)	1	2 (16.7)

^aLow versus borderline MIC.

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