Fosfomycin for the Treatment of Cystitis in the Abdominal Solid Organ Transplant Population.

STUDY OBJECTIVES

To evaluate the use of fosfomycin (FOS) at the single-dose regimen approved by the U.S. Food and Drug Administration as well as off-label multidose regimens for the treatment of cystitis after abdominal solid organ transplant (aSOT).

DESIGN

Retrospective study.

SETTING

Tertiary academic medical center.

PATIENTS

Adult inpatients with history of aSOT receiving FOS between January 1, 2009, and April 30, 2015, for the treatment of cystitis.

MEASUREMENTS AND MAIN RESULTS

Seventy-six courses of FOS were identified in 64 patients. Overall treatment success was 85.5%, with 11 failed treatment courses. Enterococcus was isolated in 59.3% of courses, of which 72.2% were vancomycin-resistant enterococci (VRE). Gram-negative organisms comprised a quarter of isolated bacteria, with most resistant to three or more antimicrobial classes. In the 11 failed treatment courses, 90% were targeted against enterococcus, of which 82% were VRE. Six of these failures (54%) were successfully retreated with uroselective therapy (FOS or nitrofurantoin). No significant difference in the success rate of single-dose versus multidose therapy was seen (80.6% vs 90%, p=0.33). Concomitant systemic antibiotics for other indications were present in 36.8% of courses, and they were significantly more frequent in the multidose group (67.5% vs 47.2%, p=0.04). However, multivariable logistic regression analysis found that after adjustment for broad-spectrum antibiotic use, no statistically significant difference in failure rates was found between the two regimens (p=0.42).

CONCLUSION

FOS appears to be successful in the treatment of cystitis in aSOT recipients. Multidose therapy did not significantly improve success over a single-dose regimen. Further prospective studies are needed to elucidate the true efficacy of FOS in the aSOT population.