ADVERTISEMENT

Departments

UroGyn Update
Urinary Tract Infection 101: Diagnosis and Therapy
Minkin MJ
The Female Patient.2011;36(10):14-18.

 Although urinary tract infections (UTIs) are seldom serious, they do pose a burden of discomfort and proper medical evaluation is warranted. Safe therapies are available but require vigilant knowledge of prevailing drug resistance patterns for optimal care.

Urinary tract infections (UTIs) are among the most common problems encountered by gynecologists. The estimated lifetime risk for experiencing a UTI is above 60% in women.1 One-third of women are diagnosed with a UTI by age 24 years, and onehalf by age 35 years. Outpatient prescriptions for UTIs in 1995 exceeded 11 million.

UTIs were described long before the antibiotic era, and herbal remedies were suggested in China as early as 3000 BCE.1 Introduced in 1953, the first antibiotic that was both well tolerated and effective (and is ironically among the current mainstays of treatment) is nitrofurantoin.

back to top


 

DIAGNOSIS

Classic symptoms of cystitis include dysuria, urgency, increased frequency, and occasionally suprapubic pain and fullness.2 Indeed, the best predictor of diagnosing a UTI is self-diagnosis.1 The reference standard for confi rming a UTI is a quantitative laboratory culture of a properly collected specimen. Not only does this diagnose the infecting bacteria, but it also provides information on antibiotic susceptibility. However, cultures are costly and take at least 48 hours to provide defi nitive information.

Several dipstick urine tests have been developed to further evaluate women with symptoms. These tests assess markers for UTIs, such as leukocyte esterase and nitrites. However, many clinicians believe that their limited positive predictive value (75% sensitivity; 82% specificity3) limits their usefulness.

Because of these issues, The American College of Obstetricians and Gynecologists (ACOG) recommends that for women without a history of laboratory-confi rmed UTI, a urinalysis or dipstick test be performed. 4 Women with recurrences (with previously confirmed infection) may be empirically treated. All women who present with suggestions of upper tract disease or pyelonephritis should have a urine culture taken. Symptoms of upper tract disease include fl ank pain, chills, fever, nausea or vomiting, and costovertebral angle tenderness.2

Risk factors for UTIs are many. Among the risk factors for premenopausal women are history of a UTI; frequent or recent sexual activity; use of a diaphragm or spermicidal agents; increasing parity; diabetes mellitus; obesity; sickle cell trait; anatomic congenital anomalies; urinary stones; and neurologic conditions requiring indwelling or frequent bladder catheterization.4

What pathogens are we seeing?
In all epidemiologic studies, Escherichia coli predominates as the leading pathogen, with most studies noting that it accounts for 75% to 80% of infections.1,5 Staphylococcus saprophyticus accounts for 4% to 15% of infections and Enterococcus, Group B streptococci, Proteus, and Klebsiella account for most other infections.

Perhaps even more important than knowing which organisms are the likeliest culprits for causing UTIs is understanding resistance patterns in your region. In a recent 9-nation European study, E coli had only a 75% sensitivity to trimethoprim- sulfamethoxazole (TMP-SMX) and 45% sensitivity to ampicillin. Clearly, resistance patterns change with time and region. Checking in with your local hospitals and outside laboratories will keep you updated on resistance patterns in your area. Resistance rates higher than 15% to 20% generally lead to a recommendation of alteration in choice of first-line therapy.5

Resistance rates to ciprofloxacin are constantly climbing. One recent study from Korea reports a 20% resistance rate of E coli to ciprofl oxacin, causing community-acquired pyelonephritis.6 In Turkey, 17% of E coli strains isolated from uncomplicated UTIs were ciprofloxacin-resistant as of 2005.7

How do we choose an antibiotic and how long should therapy last?
ACOG guidelines published in 2008 represented the first major shift in therapy in many years. Prior to that time, most gynecologists recommended a course of 7 to 10 days of therapy. However, studies show that a 3-day course of many antibiotics eradicate infections in more than 90% of patients. Recommended agents include TMP-SMX (160 mg TMP; 800 mg SMX), twice daily for 3 days, or ciprofl oxacin, 250 mg twice daily for 3 days. A 3-day course of other quinolones also may be prescribed.

If you choose to use nitrofurantoin monohydrate macrocrystals, a 100-mg dose, twice daily for 7 days, is the recommended schedule.

Recently, fosfomycin tromethamine has become available as a single dose, 3-g powder packet. It has the advantages of single-dose therapy, and resistance patterns in general show a favorable pattern in most regions, with most urinary pathogens susceptible. Another advantage is safety in pregnancy; it is a category B drug. Its major drawback is cost as it is more expensive than several other available regimens.8

Women who have pyelonephritis often require hospitalization. Even for those initially treated with outpatient therapy, most experts recommend a 14-day course of antibiotic therapy.

back to top

What if a patient experiences a recurrence?
Recurrent UTI is defined as at least 3 episodes of symptomatic uncomplicated UTI with 1 or more documented positive cultures in a 12-month period. Relapse is defined as infection with the same organism as the previous UTI. Reinfection is when cure (ie, negative follow-up culture after a symptomatic infection) is followed by further symptoms or infection. Unfortunately, up to 50% of women will develop a reinfection within 1 year of the initial UTI, and 5% will experience recurrent UTIs.2

There is little evidence that modification of patient habits will decrease the risk for recurrence. Although changes in wiping techniques, postcoital voiding, avoiding use of hot tubs, and discontinuation of wearing panty hose have been advocated for many years, these do not reduce recurrent UTIs.4 Urologists do recommend evaluation for modifiable problems, such as congenital abnormalities, obstructive issues, or prolapse. Control of diabetes and weight loss may help reduce recurrence.

There are several medical protocols that have been shown to reduce recurrent infections. Prescribing a fi rst-line agent at a reduced dosage level either daily or 3 times a week for a 6-month period has been proved effective in reducing recurrence of UTIs. Many women also succeed with use of an antibiotic prophylactically with intercourse.

Patients who prefer to not take an antibiotic routinely may benefi t from earlysymptom- stage self-administration of a course of a fi rst-line antibiotic. As noted above, self-diagnosis is a reliable screen for infections. These patients should have a course of first-line therapy available to them at all times.

Our patients ask about cranberry therapy. What should we tell them?
The belief that cranberries can prevent UTIs has existed for many years.

The Cochrane Database conducted a review of data available before January 2007 and concluded that cranberry juice may decrease the number of symptomatic UTIs over a 12-month period, especially in women with recurrent UTIs.9 However, all studies had a signifi cant number of drop-outs, possibly showing that the cranberry approach may not be well accepted over a long period of time.

Regarding mechanism of action, most studies attribute benefi cial effects of cranberry extract to its antiadhesive activity on uropathogenic E coli.10,11 The specific antiadhesion moieties are believed to be anthocyanidin derivatives, inhibiting adhesion of type 1 and P-fi mbriated uropathogens to the uroepithelium. All researchers in this area do not recommend cranberry therapy for acute treatment but suggest the possibility of therapy as prophylaxis for recurrent infections.

What about UTIs in postmenopausal women?
Many bladder symptoms, including frequency, urgency, and incontinence, increase in postmenopausal women. As with most menopausal symptoms, there is a debate about etiology as it relates to estrogen decline versus aging. The bladder is rich in estrogen receptors.12 With estrogen withdrawal and increasing atrophic vaginal symptoms, the vaginal fl ora changes and pH gradually increases, favoring the predominance of potential bladder pathogens.

Local estrogen therapy (ET) is the recommended approach to treating symptomatic atrophy in postmenopausal women with recurrent UTIs. All forms of vaginal ET, including vaginal tablets, creams, and rings, can be used. As the systemic absorption is minimal, most women are appropriate candidates for vaginal therapy.

Should women be periodically screened for asymptomatic bacteriuria?
Asymptomatic bacteriuria is defined as the presence of 100,000 microorganisms per milliliter of urine without clinical symptoms. In general, treatment is not recommended in asymptomatic cases. This, however, is not the case for pregnant women for whom first-trimester screening is recommended and therapy given for positive cultures.

back to top


 

SUMMARY

UTIs are extremely common in female patients. They are seldom serious and rarely lead to compromised renal function. UTIs do pose a burden of signifi cant discomfort on patients. Although initial medical evaluation is warranted, with at least a urinalysis and/or culture for noncomplicated recurrences, specific medical testing is not necessary. Safe treatment options are available, but knowledge of prevailing drug resistance patterns is required for optimal patient care.

Follow-up and communication with patients is helpful in continuing care for women with recurrent infections. Different management options are available, and we need to choose a regimen with which an individual patient is comfortable.

Menopausal women may require topical ET in addition to proper antibiotic management for optimum care.

The author is a consultant for Bayer, Enzymatic Therapy, Noven, Novo Nordisk, and Pfizer.

back to top


Mary Jane Minkin, MD, is Clinical Professor, Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine; and Obstetrics, Gynecology and Menopause Physician, PC, New Haven, CT.

References

  1. Foster RT Sr. Uncomplicated urinary tract infections in women. Obstet Gynecol Clin North Am. 2008;35(2):235- 248.
  2. Litza JA, Brill JR. Urinary tract infections. Prim Care. 2010;37(3):491-507.
  3. Fihn SD. Acute uncomplicated urinary tract infection in women. N Engl J Med. 2003;349(3):259-266.
  4. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 91: Treatment of urinary tract infections in nonpregnant women. Obstet Gynecol. 2008;111(3):785-794.
  5. Wagenlehner FM, Weidner W, Naber KG. An update on uncomplicated urinary tract infections in women. Curr Opin Urol. 2009;19(4):368-374.
  6. Lee SS, Kim Y, Chung DR. Impact of discordant empirical therapy on outcome of community-acquired bacteremic acute pyelonephritis. J Infect. 2011;62(2):159-164.
  7. Arslan H, Azap OK, Ergönül O, Timurkaynak F; Urinary Tract Infection Study Group. Risk factors for cipro oxacin resistance among Escherichia coli strains isolated from community-acquired urinary tract infections in Turkey. J Antimicrob Chemother. 2005;56(5):914-918.
  8. Ceran N, Mert D, Kocdogan FY, et al. A randomized comparative study of single-dose fosfomycin and 5-day ciprofl oxacin in female patients with uncomplicated lower urinary tract infections. J Infect Chemother. 2010;16(6):424-430.
  9. Jepson RG, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2008;(1):CD001321.
  10. Tempera G, Corsello S, Genovese C, Caruso FE, Nicolosi D. Inhibitory activity of cranberry extract on the bacterial adhesiveness in the urine of women: an ex-vivo study. Int J Immunopathol Pharmacol. 2010;23(2):611-618.
  11. Guay DR. Cranberry and urinary tract infections. Drugs. 2009;69(7):775-807.
  12. Hillard T. The postmenopausal bladder. Menopause Int. 2010;16(2):74-80.

ADVERTISEMENT
ADVERTISEMENT

Breaking News

More Headlines