Impact of the MIC of Piperacillin-Tazobactam on the Outcome of Patients with Bacteremia Due to Extended-Spectrum-β-Lactamase-Producing Escherichia coli

Pilar Retamar; Lorena López-Cerero; Miguel Angel Muniain; Álvaro Pascual; Jesús Rodríguez-Baño; the ESBL-REIPI/GEIH Group

doi:10.1128/AAC.00135-13

DOI: 10.1128/AAC.00135-13

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Fig 1
Mortality of patients with bacteremia due to ESBL-producing Escherichia coli treated empirically with piperacillin-tazobactam, according to source and MIC. ^aOne had severe sepsis/shock (survived). ^bOne had severe sepsis/shock (survived). ^cTwo had severe sepsis/shock (one died). ^dThree had severe sepsis/shock (two died).

Table 1

Mortality among patients with bacteremia due to ESBL-producing E. coli who were treated empirically with piperacillin-tazobactam, according to MIC and other variables of interest

Variable and group	Mortality in patients in each group^a
Variable and group	All patients (n = 39)	Low MIC (≤2 mg/liter) (n = 18)	Intermediate MIC (4 to 8 mg/liter) (n = 10)	High MIC (≥16 mg/liter) (n = 11)
All patients	7/39 (17.9)	0/18 (0)^b	3/10 (30)	4/7 (57.1)
Age
≤65 years	4/20 (20)	0/9 (0)	1/5 (20)	3/6 (50)
>65 years	3/19 (15.8)	0/9 (0)	2/5 (40)	1/5 (20)
Onset
Community	2/21 (9.5)	0/10 (0)	1/5 (20)	1/6 (16.7)
Nosocomial	5/18 (27.8)	0/8 (0)	2/5 (40)	3/5 (60)
Charlson index
≤2	4/24 (16.7)	0/12 (0)	3/8 (37.5)	1/4 (25)
>2	3/15 (20)	0/6 (0)	0/2 (0)	3/7 (42.9)
Source
Urinary tract	0/11 (0)	0/7 (0)	0/2 (0)	0/2 (0)
Other	7/28 (25)	0/11 (0)^c	3/8 (37.5)	4/9 (44.4)
Severe sepsis or shock
No	4/32 (12.5)^d	0/16 (0)	2/8 (25)	2/8 (25)
Yes	3/7 (42.8)	0/2 (0)	1/2 (50)	2/3 (66.7)
Definitive therapy^e
PTZ	0/10	0/5 (0)	0/4 (0)	0/1 (0)
Carbapenem	5/24 (20.8)	0/10 (0)	1/4 (25)	4/10 (40)
Other	0/3 (0)	0/3 (0)

↵a Data are expressed as number of patients who died/number of patients in each category (percentage). PTZ, piperacillin-tazobactam.
↵b Low MIC versus intermediate MIC, P = 0.08; low MIC versus high MIC, P = 0.005. P values were obtained by Fisher's test; only those <0.1 are shown.
↵c Low MIC versus intermediate MIC, P = 0.05; low MIC versus high MIC, P = 0.02. P values were obtained by Fisher's test; only those <0.1 are shown.
↵d Presentation without versus with severe sepsis or shock, P = 0.09. P values were obtained by Fisher's test; only those <0.1 are shown.
↵e Only patients who survived long enough to receive definitive therapy were included. Other sources included biliary tract (6), unknown and spontaneous peritonitis (2 each), and secondary peritonitis (1) for low MIC, biliary tract (4) and respiratory tract, skin and skin structure, catheter, and unknown (1 each) for intermediate MIC, and biliary tract (3), spontaneous peritonitis and skin and skin structure (2 each), and respiratory tract and secondary peritonitis (1 each) for high MIC.