Epidemiology and risk factors for extended-spectrum β-lactamase-producing organisms: A case control study at a tertiary care center in Lebanon

Background Infections caused by extended-spectrum β-lactamase (ESBL)-producing gram-negative bacilli constitute a growing problem worldwide. At the American University of Beirut Medical Center (AUBMC), we have observed a significant rise in the rates of ESBL-producing organisms over the past 5 years. Methods Using a case control study design, we compared 99 patients with infections caused by ESBL-producing Escherichia coli and Klebsiella species and 99 frequency-matched controls from which ESBL-nonproducing isolates were recovered at AUBMC. Results The most notable risk factor for acquiring infections with ESBL-producing organisms was antibiotic consumption within 30 days of the infection (OR, 7.06; 95% CI: 3.27-15.24), with third-generation cephalosporins being associated with the highest risk (OR, 28.4; 95% CI: 3.7-215.8). Other risk factors included recent surgery, presence of a urinary catheter, and need for mechanical ventilation. Moreover, cases had a longer mean duration of hospitalization and were more likely to have relapse of their infection than controls. Conclusions Recent antibiotic use is by far the most important predisposing factor to infection with ESBL-producing organisms. Such infections are associated with prolonged hospital stay and increased morbidity. Attention should be redirected toward the unjustified liberal use of broad-spectrum antibiotics both in the hospital and in the community.