When Antibiotics May Not Be the Best Course of Treatment for Suspected UTI

Patients who have positive urine cultures within 48 hours of catherization following pelvic reconstructive surgery are more likely to have non-E. coli uropathogens, with 1 out of 3 cultures being not susceptible to commonly used first line antibiotics, according to a Cleveland Clinic research study recently presented at the American Urogynecologic Society (AUGS) 2018 conference. Results of the study also will be published in Female Pelvic Medicine & Reconstructive Surgery.

“We conducted a retrospective review to determine whether or not bacterial uropathogens (UP) in individuals who have been catheterized close to pelvic reconstructive surgery differs from patients who have not been catheterized,” says Cecile A. Ferrando, MD, an Ob/Gyn in the Center for Urogynecology in Pelvic Reconstructive Surgery.

According to some studies, the postoperative urinary tract infection (UTI) rate can be as high as 40 percent, so the protocol in most urogynecologic practices is to treat the suspected UTI immediately with antibiotics like Macrodantin®, Bactrim or Cefazolin, Dr. Ferrando explains.

“However, our suspicion was that patients who had been recently catheterized after their surgery may be growing different bacteria. Our question was: Are antibiotics for those patients appropriate or should we be waiting on urine cultures before we prescribe medication?”

Data collected

The research team collected data looking at 427 positive urine cultures from 317 unique patients who had had pelvic reconstructive surgery from 2010 to 2014 at a single tertiary care referral center. Cases were divided into two groups — patients who had been catheterized after surgery and patients who had not been catheterized.

“We then examined every urine culture to determine what bacteria were growing and how susceptible those bacteria were to certain antibiotics,” Dr. Ferrando says.

Results: 247 (77.9%) patients had a single urine culture. Mean age and BMI were 62.2 ± 12.1 years and 28.9 ± 5.6 kg/m2, respectively. Forty (12.6%) patients had diabetes mellitus, 70 (22.1%) used vaginal estrogen, and 26 (8.2%) were on systemic estrogen therapy. Baseline patient characteristics were similar between non-catheterized (NC) and catheterized (C) patients except for vaginal estrogen use: NC patients were more likely to use vaginal estrogen (27.7% vs. 11.5%, P = 0.0005).

Positive urine cultures from catheterized patients were less likely to contain E. coli (47.1% NC vs. 29.2% C, P = 0.0009), with enterococcus being the most common non-E. coli UP found in this group. After adjusting for age, menopausal status, BMI, diabetes mellitus, and vaginal estrogen use, catheterized patients were twice as likely to have only non-E. coli UP (adj OR 2.16 [95% CI 1.35, 3.47], P = 0.0013) than NC patients. Cultures from catheterized patients were more likely to have a UP NS to sulfamethoxazole/trimethoprim (20.5% NC vs. 32.1% C: adj OR 2.14 [95% CI 1.17, 3.91], P = 0.01), nitrofurantoin (19.2% NC vs. 34.6% C: adj OR 2.14 [95% CI 1.35, 3.81], P = 0.002), and cefazolin (18.1% NC vs. 49.4% C: adj OR 4.55 [95% CI 2.52, 8.18], P < 0.0001). There was no difference in susceptibility to ciprofloxacin based on catheterization status.

Implications

“Patients who had been catheterized were less likely to have the common E. coli bacteria, compared to those who weren’t catheterized, which was an interesting finding,” says Dr. Ferrando. “The odds of not having E. coli were even higher for diabetics and as patients got older.

“To be clear, our conclusion is not that all patients who are catheterized and had positive cultures are not susceptible to antibiotics; they were just less likely to be susceptible compared to patients who had not had a catheter after surgery,” says Dr. Ferrando. “Our guidance would be that if a patient has a urinary tract infection after pelvic reconstructive surgery, prescribe an antibiotic, but get a culture, too. You’re more likely to have to change the antibiotic if your patient was catheterized than if they weren’t, particularly if she is diabetic or of an older age.”

Also authoring the study: Rachael C. Baird, BS, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University; Ellen Romich, BS, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University; Emily Holthaus, MD, Cleveland Clinic; and Matthew D. Barber, MD, MHS, Duke University Medical Center.