UTI: Antibiotics for ESBL

Oral Antibiotics:

• There are limited oral options for the treatment of ESBL-EC cystitis. 

Fosfomycin

•  Fosfomycin is an oral antibiotic agent that has broad activity against multi-drug resistant pathogens including ESBL-EC. 
• Fosfomycin achieves very high concentrations within the urine and is therefore an excellent agent for cystitis, but should not be used for pyelonephritis or patients with bacteremia due to inadequate concentrations within the bloodstream 
• While fosfomycin is currently only FDA-approved for the treatment of uncomplicated cystitis in women as a one-time dose of 3 grams, several studies have shown clinical efficacy in the treatment of ESBL-EC cystitis when the dosing is extended to 3 grams every 48 to 72 hours for 3 doses.
• One of the major issues with the use of fosfomycin is that susceptibility testing may not be readily available at many institutions 

Nitrofurantoin

• One study showed clinical cure rates of 69% in patients with ESBL-EC cystitis in which all isolates were also resistant to SMX/TMP and ciprofloxacin.
• should only be used for lower UTI and avoided in patients with a creatinine clearance less than 60 mL/minute as reduced renal function results in decreased active drug within the urine

References:

1. Complicated urinary tract infections: practical solutions for the treatment of multiresistant Gram-negative bacteria. J Antimicrob Chemother 2010; 65 Suppl 3: iii25–33
2. Oral Treatment Options for Ambulatory Patients with Urinary Tract Infections Caused by Extended-Spectrum-β-Lactamase-Producing Escherichia coli. Antimicrob. Agents Chemother. September 2010 vol. 54 no. 9 4006-4008
3. http://www.pharmacytimes.com/publications/health-system-edition/2013/november2013/treatment-of-esbl-producing-e-coli-lower-urinary-tract-infection