Urinary Tract Infections: Opportunities for Clinical and Stewardship Pharmacists

A urinary tract infection (UTI) is a common diagnosis in acute and outpatient care settings.¹ The high volume of antibiotics for UTIs has led to a heavy burden on the health care system, creating an opportunity for antimicrobial stewardship pharmacists to offer recommendations on appropriate therapy, duration of treatment, and unnecessary use of antibiotics.

An important aspect of the UTI diagnosis involves the presence of symptoms. Asymptomatic bacteriuria is indicative of colonization, and its treatment is not recommended, because of increased resistance and unnecessary antibiotic use.² The exceptions to this last general principle are patients who are pregnant or undergoing a urologic procedure that will involve mucosal bleeding, such as a transurethral resection of the prostate.² UTI symptoms can vary based on the location of the infection (lower or upper urinary tract). For acute cystitis, the classic symptoms are dysuria, frequency and/or urgency, and suprapubic tenderness.³ For upper UTIs, such as pyelonephritis, patients may experience any of the symptoms of cystitis, in addition to flank pain, fever, chills, nausea, and vomiting.³

Another component in the diagnosis is interpreting the urinalysis results.^4,5 For the urinalysis, a midstream, clean-catch urine sample should be collected. The urinalysis dipstick can be a useful and quick diagnostic tool for identifying UTIs. When positive, the leukocyte esterase has a positive predictive value (PPV) of about 50% (43%-56%) for the detection of a UTI, while a positive nitrite result has a PPV of about 65% (50%-83%) for infection.⁵ Another important aspect of the urinalysis is the white blood cell (WBC) count. Typically, a WBC of more than 5 to 10 per high-power field is classified as pyuria.⁴ Pyuria represents inflammation due to various causes, including infection and acute kidney injury.⁴ The absence of pyuria on urinalysis has a negative predictive value of nearly 90% (83%-95%),⁵ making infection an improbable diagnosis. Finally, pharmacists should ensure that the presence of squamous epithelial cells is not above the normal reference value, as this could lead to a contaminated urine culture. If squamous epithelial cells are high, the pharmacist should recommend a repeat urinalysis.^4,5 Once a UTI diagnosis has been established, treatment is stratified based on an uncomplicated versus complicated pathophysiology. Generally, most uncomplicated UTIs can be treated for a shorter period, compared with complicated cases, eg; 3 days instead of 7 days.³ Most of the uncomplicated cases are attributed to Escherichia coli (75%-95%),³ a gram-negative bacterium, thereby precluding the need for gram-positive coverage. For example, if a patient is prescribed both vancomycin and ceftriaxone for a UTI, the pharmacist can quickly intervene to stop vancomycin, given the unlikelihood that it would be caused by a gram-positive pathogen.

First-line treatments for uncomplicated UTIs include nitrofurantoin (Macrobid) 100 mg orally twice a day for 5 days; trimethoprim/sulfamethoxazole (Bactrim) 1 double-strength tablet orally twice a day for 3 days, if the local resistance to the latter is less than 20%; and fosfomycin 3 g orally for a one-time dose.³ If first-line options cannot be used, consider recommending an oral beta-lactam, such as cefdinir or cefpodoxime, in a regimen of 3 to 7 days or a fluoroquinolone (FQ) (examples mentioned in guidelines are ciprofloxacin, ofloxacin, and levofloxacin) for a 3-day course.³ Because of adverse effects, collateral damage, and a high risk of Clostridium difficile infection, FQs are reserved for patients who cannot tolerate any of the other treatments.^3,6 If FQs are prescribed, consider recommending narrow-spectrum ciprofloxacin 250 mg taken orally twice a day for 3 days over levofloxacin, which has a narrower spectrum of coverage.

For complicated UTIs, such as catheter-associated UTIs (CA-UTIs), the duration of treatment is usually 7 to 14 days, depending on the severity.⁷ The shortest length of treatment should always be chosen if the patient has a mild infection and/or is responding favorably to treatment.⁷ Infectious Diseases Society of America CA-UTI guidelines recommend that a 5-day course of levofloxacin 750 mg intravenously or orally daily be considered for most patients with a mild CA-UTI.⁷ If the diagnosis of a CA-UTI is made, it is recommended that the catheter be removed as soon as possible or replaced with a new one if removal is not an option and the catheter has been in place for more than 2 weeks.⁷

Leonor Rojas, PharmD, BCPS, is an antimicrobial stewardship pharmacist at Valley Hospital Medical Center in Las Vegas, Nevada.

References

• Flores-Mireles AL, Walker JN, Caparon M, Hultgren SJ. Urinary tract infections: epidemiology, mechanisms of infection and treatment options. Nat Rev Microbiol. 2015;13(5):269-284. doi: 10.1038/nrmicro3432.
• Nicolle LE, Bradley S, Colgan R, et al. Infectious Diseases Society of America guidelines for the diagnosis and treatment of asymptomatic bacteriuria in adults. Clin Infect Dis. 2005;40(5):643-654. doi: 10.1086/427507.
• Gupta K, Hooton TM, Naber KG, et al; Infectious Diseases Society of America; European Society for Microbiology and Infectious Diseases. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: a 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis. 2011:52(5);e103-120. doi: 10.1093/cid/ciq257.
• Bates BN. Interpretation of urinalysis and urine culture for UTI treatment. US Pharm. 2013;38(11):65-68. uspharmacist.com/article/interpretation-of- urinalysis-and- urine-culture- for- uti-treatment. Accessed November 15, 2017.
• Simerville J, Maxted WC, Pahira JJ. Urinalysis: a comprehensive review. Am Fam Physician. 2005;71(6):1153-1162.
• Fasugba O, Gardner A, Mitchell BG, Mnatzaganian G. Ciprofloxacin resistance in community- and hospital-acquired Escherichia coli urinary tract infections: a systemic review and meta-analysis of observational studies. BMC Infect Dis. 2015;15:545. doi: 10.1186/s12879- 015-1282- 4.
• Hooton, TM, Bradley SF, Cardenas DD, et al. Diagnosis, prevention, and treatment of catheter-associated urinary tract infection in adults: 2009 International Clinical Practice Guidelines from the Infectious Diseases Society of America. Clin Infect Dis. 2010;50(5):625- 663.