Hospital Pharmacy - February 2020 - 46

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Hospital Pharmacy 55(1)
Table 2. Microbiology and Urinary-Related Characteristics.
PTZ
(n = 39)
Organism isolateda, n (%)
Escherichia coli
36 (92.3%)
Klebsiella pneumoniae
4 (10.3%)
Klebsiella oxytoca
0 (0%)
Proteus mirabilis
0 (0%)
Urinary instrumentation, n (%)
Foley catheter
12 (30.8%)
Intermittent catheter
3 (7.7%)
4 (10.3%)
Otherb
No instrumentation
22 (56.4%)
Documented UTI characteristics, n (%)
Pyelonephritis
0 (0%)
Prostatitis
0 (0%)

Carbapenem
(n = 141)

P
value

111 (78.7%)
30 (21.3%)
1 (0.71%)
1 (0.71%)

.06
.17
1
1

47 (33.3%)
5 (3.6%)
8 (5.7%)
84 (59.6%)

.85
.37
.29
.72

10 (7.1%)
1 (0.71%)

.12
1

Note. PTZ = piperacillin-tazobactam; UTI = urinary tract infection.
a
Some patients had urine cultures with multiple organisms.
b
Includes stents, urostomy, nephrostomy, and bladder sling.

Figure 1. Patient enrollment.
a

Piperacillin-tazobactam.

Table 1. Baseline Characteristics.
PTZ
(n = 39)
Female, n (%)
ICU admission, n (%)
Age (years), mean ± SD
Weight (kg), mean ± SD
Tmaxa (°C), mean ± SD
WBCb (×109/L), mean ± SD
Comorbidities
Immunosuppressive agents
Solid organ transplant
Renal disease
Diabetes
Neurogenic bladder
Benign prostatic hyperplasia
History of urinary
incontinence
Chronic catheter
History of UTIs

Carbapenem
P
(n = 141)
value

25 (64.1%)
24 (61.5%)
71.4 ± 16.9
79.8 ± 21.3
37.4 ± 0.83
12.0 ± 6.5

106 (75.2%)
56 (39.7%)
71.1 ± 15.1
81.3 ± 25.7
37.3 ± 0.94
12.1 ± 7.0

.22
.02
.90
.71
.56
.88

1 (2.6%)
0 (0%)
12 (30.8%)
14 (35.9%)
5 (12.8%)
5 (12.8%)
2 (5.1%)
5 (12.8%)
12 (30.8%)
3 (7.7%)

9 (6.4%)
5 (3.6%)
51 (36.2%)
67 (47.5%)
11 (7.8%)
10 (7.1%)
9 (6.4%)
16 (11.4%)
50 (35.5%)
26 (18.4%)

.69
.59
.58
.21
.34
.32
1
.78
.70
.14

Figure 2. Primary outcome.

Note. PTZ = piperacillin-tazobactam; ICU = intensive care unit;
WBC = White blood cell; UTIs = urinary tract infections.
a
Maximum temperature at presentation (date of urine culture collection)
b
WBC count at presentation (date of urine culture collection)

Baseline characteristics were overall similar between the
two treatment groups, with the majority of patients being
female and mean age of approximately 71 years old (Table 1).
Approximately 62% of patients in the PTZ group required
admission to the intensive care unit (ICU) at some point
during their hospital stay compared to 40% of patients in
the carbapenem group. Table 2 describes the microbiologic

findings between the two groups with Escherichia coli representing the majority of organisms isolated, followed by
Klebsiella pneumoniae. Comorbidities in general and urinary-related comorbidities specifically were also similar
between the two groups.
No significant difference was observed between PTZ and
carbapenem for the primary outcome as clinical response
occurred in 74.4% and 80.9% of patients, respectively
(P = .38) (Figure 2). Furthermore, the groups did not differ
when comparing the incidence of repeat admissions for the
same UTI within 6 months, repeat positive urine cultures
with the same organism within 6 months, or change in antimicrobial regimen due to subjective failure as determined by
the ordering provider (Table 3).
The majority of isolates treated with PTZ had a piperacillin MIC of ≤ 4 μg/mL (Table 4). All of the cases where isolates had piperacillin MICs of 16 μg/mL and 32 μg/mL
reported met criteria for clinical response.
There was no significant difference in the mean duration
of antimicrobial therapy (5.0 vs 7.53 days; P = .32) or the mean
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