1. Average susceptibility
Effects of A Multi-faceted Antimicrobial Stewardship Model on Clinical, Microbiological and Antibiotic Utilisation Outcomes in Hospitalised Patients
T. M. Ng, D. Kee, A. Chow, C. B. Teng, M. Tan, H. L. Tay, E. L. Lew, S. H. Tan, E. Rowe, L. M. Ling, B. Ang, D. C. Lye
K-1043
Tan Tock Seng Hospital
11 Jalan Tan Tock Seng Singapore
Abstract
Results
Background: Antibiotic resistance is a major global public health concern. We describe an antimicrobial stewardship program (ASP) initiated in January 2009 which comprises of (a) persuasive interventions: hospital guidelines, prospective audit and feedback, (b) restrictive interventions: expert approval for restricted antibiotics and (c) structural interventions: computerized decision support system. The effects of these interventions on antibiotic utilisation, clinical and microbiological outcomes were analysed.
Methods: A longitudinal study was conducted from January 2007 to December Monthly data on antibiotic utilisation, hospital mortality rates (clinical outcome) and incidence of multi-drug resistant organisms (MDRO) (microbiological outcome) were collected. Segmented regression analysis on an interrupted time series was performed to determine the influence of the ASP.
Results: Use of amoxicillin-clavulanate increased with a reduction in the usage of quinolones (ciprofloxacin: mean difference; -1.20, 95% confidence interval (CI) -1.22, DDD/1000 patient days) and 3rd generation cephalosporins (ceftriaxone %CI -1.93, -1.40). Overall mortality rate decreased ( -0.11/100 deaths and discharges, 95% CI: -0.17, -0.05). There were significant reduction in incidence density of methicillin-resistant S. aureus (-2.91/ 1000 patient days, 95%CI -4.57, -1.86) and carbapenem-resistant P. aeruginosa (-2.18, 95%CI -2.51, -1.88). There were improvement of S. aureus susceptibilities to penicillin (27% to 33%); E.coli to ceftriaxone and ciprofloxacin and P. aeruginosa to ceftazidime and ciprofloxacin.
Conclusion: Our multifaceted ASP model contributed in reduction of MDROs incidence and improvement in the antibiograms of key nosocomial pathogens. There was reduction in use of selected antibiotic as well as overall mortality
Table 1. Antimicrobial utilization rate (DDD/1000 patient days),
Log-transformed IV antibiotic utilisation rate (DDD/1000 patient days),
Antibiotic
Mean difference
95% CI
Amoxicillin clavulanate
0.75
0.66, 0.85
Ceftazidime
-0.46
-0.59, -0.34
Ceftriaxone
-0.61
-0.66, -0.57
Ciprofloxacin
-0.18
-0.20, -0.15
Levofloxacin
-0.21
-0.26, -0.16
Ertapenem
0.57
-0.26, 1.40
Imipenem
-0.17
-0.32, -0.02
Meropenem
-0.002
-0.16, 0.15
Piperacillin tazobactam
STATA statistical error
Polymixin B
0.64
0.47, 0.81
Vancomycin
0.18
-0.04, 0.40
Table 2. . Change in incidence of Multi-Drug Resistant Organisms (MDRO), post-intervention
Log-transformed incidence density (first lab-confirmed isolate per patient/1000 patient days)
MDROs
Mean difference
95% CI
Methicillin-resistant S. aureus
-1.07
-1.52, -0.62
Vancomycin-resistant Enterococcus sp.
0.01
-0.04, 0.07
Carbapenem-resistant A. baumannii
0.26
-0.11, 0.70
Carbapenem-resistant P. aeruginosa
-0.78
-0.92, -0.63
ESBL E. coli
0.02
-0.74, 0.79
ESBL K. pneumoniae
-0.64, 0.68
C. difficile
-0.01
-1.20, 1.17
Introduction
Antibiotic resistance increases mortality and prolonged hospitalization.
Antimicrobial stewardship limits inappropriate use and optimizes antibiotic therapy
Our ASP program which comprises of (a) persuasive interventions: dissemination of hospital guidelines, audit and feedback, (b) restrictive interventions; expert approval for restricted antibiotics by infectious disease specialist and (c) structural interventions; computerized decision support system.
Table 3. Changes in antibiogram of selected organisms
Bold >5% change, * * signifies data not a good fit to possion model.
Objective
Average susceptibility
Specimen type
Blood
All sites
Pre-ASP
Post-ASP
S. aureus
Penicillin
26.5
25.0
33.0
25.7
Ciprofloxacin
95.0
95.5
88.0
91.7
E. coli
Ceftriaxone
77.0
71.0
78.0
73.7
66.5
50.5
69.0
53.3
Amoxicillin clavulanate
79.0
68.3
Piperacillin-tazobactam
98.0
97.3
94.7
Ertapenem
100.0
99.7
K. pneumoniae
69.5
55.0
72.3
61.3
67.0
48.5
67.3
57.0
Amoxicillin-clavulanate
73.0
61.0
70.0
58.0
84.0
74.0
84.7
78.3
P. aeruginosa
Ceftazidime
75.0
74.5
73.3
84.3
92.5
86.0
92.7
88.3
Imipenem
82.0
85.3
85.7
71.5
70.5
83.7
79.3
A. baumannii
48.0*
31.5
31.3*
19.3
46.0*
25.5
30.7*
16.0
45.0*
26.0
29.0*
17.3
Describe the effect our ASP interventions on antibiotic utilisation, clinical and microbiological outcomes.
Methods
A longitudinal study was conducted from January 2007 to December 2011
All aspects of ASP program implemented from January 2009 to September 2009 and continued through December 2011
All data was obtained from in-house surveillance database which received data feeds from pharmacy, microbiology and hospital administration databases
Segmented regression analysis using ARIMA models on an interrupted time series was performed to determine the influence of ASP on antibiotic utilization and incidence of mullet-drug resistance organisms
Poisson regression was used to measure the change in mortality rate and the expected difference in log count of antibiotic susceptibility for comparisons of annual antibiograms
Figure 1. Mortality per 100 deaths and discharges in TTSH between Jan Dec 2011
Conclusion
Our multifaceted ASP model contributed in reduction of MDROs incidence and improvement in the antibiograms of key nosocomial pathogens.
There was reduction in use of selected antibiotic as well as overall mortality