Incidence of fluoroquinolone-resistant and extended-spectrum β-lactamase-producing escherichia coli at a comprehensive cancer center in the United States

Background: Quinolones are used extensively for prophylaxis in high-risk cancer patients; however, increasing quinolone resistance is being reported. Extended-spectrum β-lactamase (ESBL)-producing E. coli may be associated with increased morbidity and mortality particularly in neutropenic cancer patients. Methods: We conducted a retrospective study of consecutive E. coli isolates from January 2009 to August 2009 at our institution. Data on antimicrobial susceptibility of E. coli isolates to commonly used antimicrobial agents and the frequency of ESBL production and fluoroquinolone resistance were gathered based on CLSI guidelines. Results: There were 443 isolates of E. coli recovered. The majority were from urine cultures (308 isolates, 69.5%). Forty-one (9.2%) isolates were ESBL producing. Nine (18.3%) of the 49 isolates recovered from blood stream infections were ESBL producing. Quinolone resistance was present in 204 isolates (46%). Carbapenems and aminoglycosides retained excellent activity. E. coli resistance to quinolones increasedfrom 13 to 46% in a period of 13 years (p = 0.001). Conclusion: The incidence of resistance to quinolones at our center may be increasing as a consequence of widespread use of quinolones as prophylaxis for neutropenic patients. ESBL-producing E. coli are frequent at our center and are associated with blood stream infections.