Impact of antibiotic utilization measures on acquisition rate of extended spectrum β-lactamase enzymes producing bacteria

Introduction

Antibiotic resistance patterns are continually changing; a new problem has been the emergence of Gram-negative bacteria, primarily Escherichia coli and Klebsiellae pneumoniae, producing extended spectrum β-lactamase enzymes (ESBL). Antibiotic use measures are presumably the most important intervention in preventing their clonal outbreak, and the risk factors for ESBL include intensive antibiotic exposure (especially third-generation cephalosporin monotherapy). The present study was performed to determine the impact of using piperacillin/tazobactum in reducing the acquisition rate of ESBL producing Gram-negative bacteria in the ICU.

Methods

This open-label, prospective study was carried out in 140 adult patients admitted to the ICU over a period of 9 months, and was divided into two phases. Phase I (pre-intervention phase, 0–3 months): upon admission to the ICU, besides standard investigations, additional rectal swab cultures were taken for detection of ESBL within and after 48 hours of admission, and were repeated every 7 days of the stay in the ICU. Routinely prescribed antibiotics were allowed. Phase II (intervention phase, 4–9 months): this was subdivided into (a) first 3 months (4–6 months): piperacillin/tazobactum was the primary antibiotic used (more than 50% replacement of cephalosporins), and (b) last 3 months (7–9 months): here again, rectal swab cultures were taken and piperacillin/tazobactum was the primary antibiotic used. McNemar's test and Fisher's exact test were used for statistical analysis.

Results

Eighty-five patients in phase I and 55 patients in phase II were enrolled. Third-generation cephalosporins were the primary antibiotic in 75.2% of cases in phase I and in 1.8% of cases in phase II (P < 0.001). The incidence of ESBL was 62.3% in phase I and it came down to 34.5% in intervention phase II (P < 0.01).

Conclusion

Data from this intervention study support the concept that third-generation cephalosporins are of substantial importance in the emergence of ESBL; by decreasing the level of third-generation cephalosporin use and increasing the piperacillin/tazobactum use, their was a notable reduction in the acquisition rate of ESBL producing E. coli.