Making Sense of Antimicrobial Resistance Surveillance: A successful intervention

Abstract

Background: The intensive care units are epicenters for the emergence of antibiotic resistant Gram-negative bacteria because of the high use of antibiotics, prolonged hospital stay, reduced patient immunity, use of medical devices, and the frequent contact between healthcare workers and patients. Surveillance of bacterial resistance is the key element to understand the size of the problem, drive interventions, and measures the effect of these measures. Several reports have linked the use of third generation cephalosporins with β-lactam resistance in gram-negative bacteria. Several strategies were introduced by the Antibiotic Stewardship Programs to reduce antibiotic resistance but the efficacies of these interventions are not well studied. Methods: The Microbiology Laboratory of Hamad Medical Corporation (HMC) monitors antimicrobial resistance by continuous surveillance using the National Committee for Clinical Laboratory Standards (NCCLS) - currently Clinical Laboratory Standards Institute interpretive criteria. Surveillance data were released annually and shared with clinicians and policy makers for review of the antibiotic policy and the antibiotic formulary. Results: Surveillance data in 2001 showed high level β-lactam antibiotics resistance and high level production of extended spectrum β-lactamases (ESBL) among gram-negative bacteria. As a result, the Hospital Antibiotic Policy Committee decided to withdraw ceftazidime a third –generation cephalosporin known to be a strong inducer of ESBL, from the hospital formulary. Subsequent resistance surveillance over the following three years in the Medical Intensive Care unit (MICU) demonstrated a gradual drop in the resistance of Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli; the commonest isolated gram negative bacteria from MICU), not only to third and fourth generation cephalosporins, but also to Piperacillin – Tazobactam in spite of the increased use of the later drug in the MICU. Discussion and conclusion: Antibiotic resistance is an increasing global problem. Surveillance studies are needed to monitor resistance development, to guide local empirical therapy, and to implement timely and adequate countermeasures. Since resistance development is an evolutionary process, constant surveillance is necessary to gain insight into the problem in a timely fashion. Several measures were taken including antibiotic cycling, antibiotic rotation and restriction. Restriction of the use of Ceftazidime resulted in a significant drop in the resistance of the common Gram-negative bacteria to the betalactam antibiotics. The sustainability and efficacy of these measures need to be monitored over time.