Short-course Methenamine Hippurate for Prevention of Post-operative UTI

Prevention of post-operative urinary tract infections (UTI) is becoming important for both
the individual patient and the health system. Complications of UTI include pyelonephritis and
bacteremia, requiring hospitalization and parenteral antibiotics. Additionally, recurrent
exposure to antibiotics commonly given for UTIs increases the risk of antibiotic resistance
to uropathogens. UTIs also increase economic burdens on the health care system, with each
episode costing nearly 600 dollars. UTIs associated with catheterization are particularly
costly for hospitals, resulting in decreased hospital quality measures and lack of
compensation.

This is particularly important after pelvic reconstructive surgery, as reported rates of UTI
reach up to 20-25%. Urinary retention requiring short-term indwelling catheterization, common
in these women, contributes to the risk of UTIs by increasing the risk of bacteriuria by
5-10% per day and through the dislodging of bacterial colonies during catheter removal.
Balancing prevention and resistance and cost is key. A meta-analysis by Marschall et al
indicated the benefit of a short dose of antibiotic prophylaxis at catheter removal in
general post-surgical patients. However, data is lacking on the effects of daily antibiotic
prophylaxis on resistance and cost.

A possible alternative to antibiotics presents itself in methenamine hippurate, a urinary
antiseptic which forms formaldehyde in the presence of acidic urine. It is relatively
inexpensive, and does not induce resistance in vivo. Prior studies have shown that daily use
of methenamine can decrease the risk of post-operative UTI.

The purpose of our study was to investigate the efficacy of a short course of methenamine
hippurate at catheter removal to that of a short course of ciprofloxacin in prevention of
UTIs after short-term indwelling catheterization. Additionally, we investigated factors that
influence post-operative UTIs, the rate of culture-proven UTIs after prophylaxis, the
antibiotic resistance profile of those undergoing prophylaxis, and the cost effectiveness of
prophylaxis.

Inclusion Criteria:

- female;

- patients who are able to read and write English;

- 18 years of age or older;

- underwent surgery for pelvic organ prolapse, urinary incontinence, or both;

- require post-operative short-term transurethral catheterization for greater than 24
hours.

Exclusion Criteria:

- patients undergoing surgical intervention for sacral neuromodulation, or mesh
excision;

- patients requiring long-term catheterization secondary to injury to the urinary tract;

- patients who pass their post-operative trial void and thus, do not require additional
catheterization;

- patients requiring catheterization for less than 24 hours;

- pregnant patients;

- patients who are breast-feeding;

- allergy to methenamine hippurate or fluroquinolones (either ciprofloxacin or
levofloxacin);

- impaired renal or hepatic function;

- pre-operative urinary retention;

- patients who are currently using sulfonamides;

- patients who have severe dehydration;

- patients using tizanidine;

- patients sensitive to quinolones class;

- patients using theophylline; patients with myasthenia gravis;

- patients with prolongation of QT interval.