Urinary tract infections and asymptomatic bacteriuria in older adults Abstract: Overuse of urinalysis in older adults to investigate vague changes in condition such as confusion, lethargy, and anorexia, has led to overtreatment of asymptomatic bacteriuria and associated antibiotic resistance.
rinary tract infections (UTIs) are some of the most commonly diagnosed bacterial infections in older adults and pose a significant clinical and financial burden to patients and healthcare providers alike.1 Symptomatic UTI is defined as the presence of bacteria in the urine at defined quantitative levels (generally 105 colony forming units per milliliter [CFU/mL]), with concomitant symptoms attributable to the genitourinary tract, such as dysuria, frequency, urgency, and flank or suprapubic pain.2 It is important to accurately identify UTI in older adults to
U
avoid complications, such as falls, sepsis, and death.3-5 However, diagnosis is often complicated by communication difficulties and cognitive impairment in this population, and clinicians frequently rely on urinalysis to diagnose infections.6 This is not an accurate method of diagnosis due to the prevalence of asymptomatic bacteriuria (ASB) in older adults.1,7 Urine culture should instead be used to guide antibiotic selection in the presence of UTI symptoms.6 ASB is defined as the presence of bacteriuria on microscopy or in urine culture from a patient who does not
Keywords: asymptomatic bacteriuria, older adults, urinary tract infection
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The Nurse Practitioner • August 2015 43
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By Joan M. Nelson, DNP, ANP and Elliot Good, MS, AGNP
Urinary tract infections and asymptomatic bacteriuria in older adults
have symptoms attributable to the genitourinary tract.8 The incidence of ASB increases with age to nearly 20% of community-dwelling women and 15% of communitydwelling men over the age of 75. 8 This number is even higher in long-term care facilities, where nearly 50% of female residents and 40% of male residents have ASB.9 Symptomatic UTIs occur relatively infrequently in comparison, with a point-prevalence rate estimated at 1.1%.10 Unfortunately, the diagnosis of UTI is often made in the setting of a positive urine culture and absence of a positive clinical history of genitourinary symptoms, resulting in misdiagnosis and overtreatment.8,11,12 ■ Testing and treatment Testing and treatment of ASB is not recommended in the general older-adult population, as it has not been shown to reduce risk and may instead contribute to poor outcomes.9,11 Randomized controlled trials have shown that treatment of ASB may, in fact, increase the risk of developing symptomatic UTI.7 In addition, treating ASB does not improve incontinence rates, reduce the risk of recolonization of the urinary tract, or lower the rate of hospitalization and death.8 Instead, the inappropriate treatment of ASB contributes to the overuse of antibiotics, which is a well-recognized problem among older adults. Antibiotic treatment can have profound effects on natural intestinal flora and lead to the development of antibiotic-associated diarrhea, including Clostridium difficile infection and pseudomembranous colitis, which are leading causes of morbidity and mortality in older patients.11,13 In addition, inappropriate antibiotic-prescribing practices have contributed to the growing emergence of antibiotic-resistant organisms, which complicate therapeutic options, lead to greater illness, and increase cost of treatment. 14 Escherichia coli (E. coli), the bacterium most frequently implicated in UTI, is becoming increasingly
suffering, increases cost to the healthcare system, and is a significant public-health concern that warrants both close attention to prescribing practices and careful adherence to medication regimens. When a symptomatic UTI does warrant treatment, the judicious choice of a narrow-spectrum antibiotic, guided by local antibiograms, can further reduce the risk of unnecessary antibiotic exposure and the development of antimicrobial resistance.8,11,14 Clinicians must avoid the empirical use of broad-spectrum antibiotics in the treatment of UTI.11,16 Despite the strong evidence against treatment of ASB, studies have suggested that, in practice, patients often get treated for bacteriuria in the absence of urinary symptoms.8,9 In fact, one-third to one-half of patients who test positive for ASB receive antibiotic treatment.16,17 Reasons for treatment include the diagnostic challenges posed by the sometimes vague presentation of UTI in the older adult.18 Several diagnostic algorithms aimed at preventing the inappropriate treatment of ASB have been developed, and studies have shown that implementation of antibioticstewardship programs can have a positive effect on the reduction of overtreatment of ASB and improve patient outcomes.19-21 However, treatment of ASB is still common, and increased quality measures are needed to raise clinical practice to the level of evidence-based standards in the diagnosis and management of UTI.9,11
■ Etiology In the younger-adult population, UTI occurs significantly more often among women than among men.1 Reasons include the proximity of the urethral opening in women to the perianal area and the relative ease of bacterial migration. The female urethra is also shorter in length, which eases bacterial transit to the bladder. UTI in the younger adult male is rare and is usually related to some degree of anatomical abnormality or immunological defect.22 As they age, both men and women face increased prevalence of ASB and symptomatic The incidence of ASB increases to nearly 20% UTI. There are a number of physiologic, cognitive, and behavioral reasons for of community-dwelling women and 15% of this increase. Neurologic abnormalities, community-dwelling men over age 75. such as Alzheimer disease, Parkinson disease, or cerebrovascular disease can result in impaired bladder emptying, urinary retention, and incontinence, which can require resistant to first-line antibiotic treatment. Patients infected 6 catheterization. The use of catheters and urine-collection with antibiotic-resistant strains of E. coli are more likely to be hospitalized and are at greater risk of complication and devices can introduce bacteria into the bladder. Patients with death from infection.15 When pathogens become resistant diabetes mellitus, particularly those with poor glycemic control, are also at greater risk.23 Urological conditions that to first-line treatment, second- and third-line treatments must be used and are often less effective, more toxic, and result in obstruction of urine flow, such as urolithiasis or more expensive.11 Antibiotic resistance worsens patient tumor, lead to urine stasis and growth of bacteria.6
44 The Nurse Practitioner • Vol. 40, No. 8
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Urinary tract infections and asymptomatic bacteriuria in older adults
As postmenopausal women experience a loss of estrogen, the pH of the vaginal and urethral tissues rises, thus, reducing lactobacillus levels and increasing susceptibility to bacterial colonization.24 Cystoceles are associated with an increase in recurrent UTI related to a rise in post-void residual. In addition, impaired voiding patterns and changes in hygiene increase the risk of UTI in older women.6 Older male patients are at increased risk for UTI related to the development of benign prostatic hyperplasia (BPH) and bladder retention. 2 The prevalence of BPH increases with age so that 60% of 60-year olds and over 80% of 80-year-old males have this condition.25 A lifetime history of UTI is also a significant predictor of UTIs in later life.1
Proteus mirabilis, Pseudomonas aeruginosa, Klebsiella, yeast, and Enterobacter.1 ■ Clinical presentation Lower UTIs are confined to either the bladder (cystitis) or the urethra (urethritis) and often present with dysuria, frequency, urgency, and occasionally, suprapubic tenderness. UTIs involving the upper urinary tract and kidneys (pyelonephritis) are accompanied by more severe symptoms, such as fever, chills, nausea, vomiting, and flank pain.26 Older adults with cognitive dysfunction are, unfortunately, often unable to accurately report these symptoms. UTIs can lead to serious complications. Up to 8% of falls in residential care facilities were linked to symptomatic UTIs in one study, perhaps due to the presence of urinary urgency and frequency.5 Gau and colleaues reported falls in 24% of hospitalized older adults with UTI versus only 4% of those with ASB.4 About 5% of cases of sepsis are caused by UTIs.27 Risk factors for the development of sepsis from a UTI include female gender, structural or functional condition that obstructs the flow of urine, impaired immunity, or comorbid disease.27 Because of the importance of correctly distinguishing UTI from ASB, a minimum set of criteria to guide urinalysis-ordering in long-term care settings, the McGeer criteria was identified/
■ Pathogenesis Urine is normally sterile but can become a good medium for growth when bacteria invade the bladder and are not eliminated. The most common means of bacterial entry into the urinary tract is ascension from the urethral opening.2 Bacteria are normally present around the urethral opening in both men and women, and the lower third of the urethra is frequently contaminated with bacteria.1 These bacteria are normally flushed out with micturition and do not ascend far enough to cause symptoms. The female urethra is relatively short and proximal to the vagina and rectum, which have abundant microbial Lower UTIs are confined to either the bladder or communities. In the presence of an anatomical or functional abnormality—or the urethra and present with dysuria, frequency, following sexual activity, urethral masurgency, and occasionally, suprapubic tenderness. sage, or catheterization—bacteria travel up the urethra toward the bladder and upper urinary tract structures.6 In men, developed in 1989 and updated/revised 11 years later by prostatic hypertrophy contributes to urinary retention and Loeb.28,29 These infection-surveillance definitions were impaired voiding patterns, which lead to urine stasis and the 2 subsequent growth of bacteria. developed for long-term care residents who had impaired cognition and functional status or required skilled nursing The most commonly isolated organism in 80% to 90% care.30 These criteria were reviewed and updated in 2009 of ASB and symptomatic UTI is Gram-negative, uropatho1 genic E. coli. These uropathogenic strains of E. coli are based on a literature review and updated consensus opinions.30 Change in urine characteristics, which had been different from the strains that normally colonize the gastrointestinal tract in that they have enhanced ability to included in both the original McGeer and Loeb criteria, colonize the urinary tract and evade the host’s immune was removed from the updated recommendations because response. For example, uropathogenic E. coli have virulence it does not distinguish UTI from ASB. Likewise, altered factors that enhance fimbrial adhesions to urethral mental status, which was one of the Loeb criteria, was epithelial tissue, facilitating the establishment and persisfound poorly to distinguish true infection from ASB and tence of colonization. These strains of E. coli are highly has been removed from the updated criteria. This update heterogeneous, and as of yet, there is no test available to emphasizes the need to ensure that symptoms of UTI are determine E. coli uropathogenicity unless the sample is new or worsened, alternative explanations for the signs and obtained directly from the urinary tract. Other than E. symptoms are evaluated, and microbiologic and clinical coli, the remaining 10% to 20% of UTIs are caused by evidence are combined in making a diagnosis of infection.30 microorganisms such as Staphylococcus saprophyticus, (See The updated UTI-surveillance criteria.) www.tnpj.com
The Nurse Practitioner • August 2015 45
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Urinary tract infections and asymptomatic bacteriuria in older adults
McGeer and Loeb criteria have been widely adopted for use in long-term care, but they remain merely expert opinion without much supporting evidence. JuthaniMehta and colleagues correlated clinical symptoms with microbiologic findings of bacteriuria and pyuria, reporting sensitivities of both the original McGeer criteria and the Loeb criteria to be poor (McGeer 30%, Loeb 19%).31 Falsepositive tests were uncommon, but specificity was likely overestimated because lab testing is a poor gold standard for infection. Most of these criteria rely on older adults’ reports of subjective symptoms; however, this information is not obtainable in older adults who are cognitively impaired, and it is difficult to assess in those with underlying urinary incontinence. The updated UTI-surveillance criteria30 The updated UTI-surveillance criteria require the following for diagnosis of UTI in patients without an indwelling catheter: At least one of the following signs or symptoms: • Acute dysuria or acute pain, swelling, or tenderness of the testes, prostate, or epididymis • Fever or leukocytosis AND at least one of the following - Acute costovertebral angle (CVA) tenderness or pain - Suprapubic pain - Gross hematuria - Marked increase in or new-onset incontinence, urinary urgency, or frequency OR • If no fever or leukocytosis, at least two of the following: - Suprapubic pain - Hematuria - Marked increase in or new-onset incontinence, urinary urgency, or frequency AND • At least 105 CFU/mL of no more than two species of bacteria in a voided urine specimen • At least 102 CFU/mL of any number of microorganisms in a straight catheter-obtained urine sample Patients with urinary catheters must demonstrate at least one of the following: • Fever, chills, or new-onset hypotension without alternate site of infection • Acute change in mental status or functional decline AND leukocytosis without alternate site of infection • New-onset suprapubic pain or CVA pain/tenderness • Purulent discharge from the catheter site OR acute pain, swelling, or tenderness in the testes, prostate, or epididymis AND • At least 105 CFU/mL of any organism cultured from catheter specimen after replacement of catheter if it has been in place for more than 2 weeks.
■ Diagnostic testing UTIs are frequently classified according to location, presence or absence of complicating factors, and frequency of infection. A complicated UTI is an infection that occurs in the presence of an underlying condition that increases the risk of therapeutic failure.8 The majority of the time, cystitis and pyelonephritis in an otherwise healthy woman are considered uncomplicated, though some regard older female patients as complicated due to functional or structural abnormalities of the urinary tract that are common in this population.8 UTIs in men have traditionally been considered complicated, but recently, it has been acknowledged that healthy men can occasionally develop acute, uncomplicated UTIs (most often related to anal intercourse).32 The diagnosis of recurrent UTI is made following two or more infections in 6 months or three or more infections in 1 year. For uncomplicated lower UTIs, there is no evidence that recurrence leads to chronic health problems, including kidney disease.6 Recurrent pyelonephritis is uncommon. When urine is tested in asymptomatic patients and found to be contaminated with bacteria, a diagnosis of ASB is made. The diagnosis of ASB for noncatheterized older women is based on a culture of two consecutive clean, midstream catches of urine that demonstrate bacterial counts of greater than 10 5 CFU/mL of the same organism. Men require only one urinary sample with this quantity of a single bacterial organism to be diagnosed with ASB.8 Lab data are ineffective in distinguishing ASB from UTI because bacterial counts, cultures, and the presence of pyuria do not distinguish between these conditions.8 Pyuria, without infection, is present in 90% of institutionalized older adults. E. coli is the most common organism associated with the urinary tract and is found in both UTIs and ASB. Urine dipstick testing has been found to be of little value in the diagnosis of UTI in older adults.6 The positive and negative predictive values of urine dipstick tests are no better than those based on evaluation of clinical symptoms using either Loeb or McGeer criteria.6 The use of urine culture combined with assessment of clinical symptoms is the best way to diagnose UTI in older adults.8 ■ Treatment The Infectious Disease Society of America has developed guidelines for treatment of uncomplicated UTI in women, catheter-associated UTI, and ASB.33 The uncomplicatedUTI guideline (which specifically excludes postmenopausal women) recommends trimethoprim-sulfamethoxazole (TMP-SMX), nitrofurantoin, and fosfomycin as first-line empiric therapies for uncomplicated infections.33
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Urinary tract infections and asymptomatic bacteriuria in older adults
E. coli species cultured from long-term care residents have acquired a great deal of resistance to many of the antibiotics used to treat UTIs in practice.34 Twenty-five percent of isolates from this population were resistant to TMP-SMX, and 60% were resistant to fluoroquinolones.34 More than 90% of organisms were susceptible to nitrofurantoin, but use of this medication is limited to adults with a glomerular filtration rate greater than 60.34 To minimize development of antibiotic resistance, narrow-spectrum antibiotics should be used to treat infection, and the choice of the agent should be guided by the urine culture and antibiograms, which show local patterns of microbial resistance. Three days of therapy for infection in older women has been shown to be sufficient.35 Prevention of recurrence is an important part of the treatment plan. Daily intake of cranberry juice or tablets may be effective in helping to prevent UTIs, especially in cases of recurrent infection, though the exact strength of the tablet or amount of juice required has not been established.36 Vaginal estrogen and increasing fluid consumption have been found to prevent UTI recurrence in postmenopausal women.24,37 Good perineal care and frequent changing of incontinence briefs can reduce the incidence of UTIs because skin chafing and rashes compromise an important barrier to infection and because fecal soiling introduces infectious organisms to the urinary tract. This article has focused on noncatheter-associated UTI, but the use of indwelling catheters poses a high risk for UTI. Catheterization should be avoided when possible, and duration of use should be limited. ■ Implications for practice Pharmaceutical companies have dramatically slowed development of new antibiotics, yet antibiotic resistance to pathogens is increasing.14 UTIs are one of the leading causes of antibiotic use among older adults and are associated with the development of sepsis from a UTI and hospitalizations.9 On the other hand, the prevalence of ASB ranges from 23% to 50% in institutionalized older adults.38 Mistaking ASB for symptomatic UTI can lead to inappropriate antibiotic use and increased risk for C. difficile infection, drug allergies/adverse drug reactions, and antibiotic resistance. This article focused on older adults, especially those living in long-term care facilities, because this population has very high rates of ASB and is most at risk for complications developing from antibiotic overuse. One-third of antibiotic prescriptions for a presumed UTI are actually given inappropriately for ASB.38 Implementation of UTI-surveillance criteria can help decrease inappropriate use of antibiotics by at least 30%.38 Appropriate selection of antibiotic therapies and duration of www.tnpj.com
treatment can further help to avoid infection recurrence and multiple drug resistance. REFERENCES 1. Foxman B. The epidemiology of urinary tract infection. Nat Rev Urol. 2010; 7(12):653-660. 2. Genao L, Buhr GT. Urinary tract infections in older adults residing in longterm care facilities. Ann Longterm Care. 2012;20(4):33-38. 3. Søgaard M, Sch¯nheyder HC, Riis A, S¯rensen HT, N¯rgaard M. Short-term mortality in relation to age and comorbidity in older adults with communityacquired bacteremia: a population-based cohort study. J Am Geriatr Soc. 2008; 56(9):1593-1600. 4. Gau JT, Shibeshi MR, Lu IJ, et al. Interexpert agreement on diagnosis of bacteriuria and urinary tract infection in hospitalized older adults. J Am Osteopath Assoc. 2009;109(4):220-226. 5. Kallin K, Jensen J, Olsson LL, Nyberg L, Gustafson Y. Why the elderly fall in residential care facilities, and suggested remedies. J Fam Pract. 2004;53(1): 41-52. 6. Beveridge LA, Davey PG, Phillips G, McMurdo ME. Optimal management of urinary tract infections in older people. Clin Interv Aging. 2011;6:173-180. 7. Bengtsson C, Bengtsson U, Bjˆrkelund C, Lincoln K, Sigurdsson JA. Bacteriuria in a population sample of women: 24-year follow-up study. Results from the prospective population-based study of women in Gothenburg, Sweden. Scand J Urol Nephrol. 1998;32(4):284-289. 8. Nicolle LE, Bradley S, Colgan R, Rice JC, Schaeffer A, Hooton TM. Infectious Diseases Society of America guidelines for the diagnosis and treatment of asymptomatic bacteriuria in adults. Clin Infect Dis. 2005;40 (5):643-654. 9. Lin K, Fajardo K, Force USPST. Screening for asymptomatic bacteriuria in adults: evidence for the U.S. Preventive Services Task Force reaffirmation recommendation statement. Ann Intern Med. 2008;149(1):W20-W24. 10. Tsan L, Davis C, Langberg R, et al. Prevalence of nursing home-associated infections in the Department of Veterans Affairs nursing home care units. Am J Infect Control. 2008;36(3):173-179. 11. Gross PA, Patel B. Reducing antibiotic overuse: a call for a national performance measure for not treating asymptomatic bacteriuria. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2007;45(10):1335-1337. 12. Woodford HJ, George J. Diagnosis and management of urinary tract infection in hospitalized older people. J Am Geriatr Soc. 2009;57(1):107-114. 13. Dethlefsen L, Huse S, Sogin ML, Relman DA. The pervasive effects of an antibiotic on the human gut microbiota, as revealed by deep 16S rRNA sequencing. PLoS Biol. 2008;6(11):e280. 14. Spellberg B, Guidos R, Gilbert D, et al. The epidemic of antibiotic-resistant infections: a call to action for the medical community from the Infectious Diseases Society of America. Clin Infect Dis. 2008;46(2):155-164. 15. Hoban DJ, Nicolle LE, Hawser S, Bouchillon S, Badal R. Antimicrobial susceptibility of global inpatient urinary tract isolates of Escherichia coli: results from the Study for Monitoring Antimicrobial Resistance Trends (SMART) program: 2009-2010. Diagnostic microbiology and infectious disease. 2011;70(4):507-511. 16. McMurdo ME, Gillespie ND. Urinary tract infection in old age: overdiagnosed and over-treated. Age Ageing. 2000;29(4):297-298. 17. Nicolle LE. Asymptomatic bacteriuria: when to screen and when to treat. Infect Dis Clin North Am. 2003;17(2):367-394. 18. Chant C, Dos Santos CC, Saccucci P, Smith OM, Marshall JC, Friedrich JO. Discordance between perception and treatment practices associated with intensive care unit-acquired bacteriuria and funguria: a Canadian physician survey. Crit Care Med. 2008;36(4):1158-1167. 19. Buhr GT, Genao L, White HK. Urinary tract infections in long-term care residents. Clin Geriatr Med. 2011;27(2):229-239. 20. Chowdhury F, Sarkar K, Branche A, et al. Preventing the inappropriate treatment of asymptomatic bacteriuria at a community teaching hospital. J Community Hosp Intern Med Perspect. 2012;2(2). 21. File TM Jr., Solomkin JS, Cosgrove SE. Strategies for improving antimicrobial use and the role of antimicrobial stewardship programs. Clin Infect Dis. 2011;53(suppl 1):S15-S22. 22. Griebling T. Urinary tract infection in men. In: Disease NIoDaDaK, ed. Urologic Diseases in America. Washington, DC: Government Printing Office; 2007.
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Urinary tract infections and asymptomatic bacteriuria in older adults
23. Zhanel GG, Nicolle LE, Harding GK. Prevalence of asymptomatic bacteriuria and associated host factors in women with diabetes mellitus. The Manitoba Diabetic Urinary Infection Study Group. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 1995;21(2):316-322. 24. Perrotta C, Aznar M, Mejia R, Albert X, Ng CW. Oestrogens for preventing recurrent urinary tract infection in postmenopausal women. Cochrane Database Syst Rev. 2008;(2):CD005131. 25. Cunningham G, Kadmon D. Epidemiology and pathogenesis of benign prostatic hypertrophy. http://www.uptodate.com/contents/epidemiologyand-pathogenesis-of-benign-prostatic-hyperplasia. 26. McCance KL HS, Brashers VL, Rote NS. Pathophysiology: The Biological Basis for Disease in Adults and Children. 6th ed. Maryland Heights, MO: Elsevier; 2010. 27. Kalra OP, Raizada A. Approach to a patient with urosepsis. J Glob Infect Dis. 2009;1(1):57-63. 28. McGeer A. Definitions of infection for surveillance in long-term care facilities. 1996. https://www.premierinc.com/safety/topics/guidelines/ downloads/25_itcdefs-91.pdf. 29. Tal S, Guller V, Levi S, et al. Profile and prognosis of febrile elderly patients with bacteremic urinary tract infection. J Infect. 2005;50(4):296-305. 30. Stone, ND. Surveillance definitions of infections in long-term care facilities: revisiting the McGeer Criteria. Infection Control Hospital Epidemiology. 2012;33(10):965-977. 31. Juthani-Mehta M, Tinetti M, Perrelli E, Towle V, Van Ness PH, Quagliarello V. Diagnostic accuracy of criteria for urinary tract infection in a cohort of nursing home residents. J Am Geriatr Soc. 2007;55(7):1072-1077.
34. Das R, Perrelli E, Towle V, Van Ness PH, Juthani-Mehta M. Antimicrobial susceptibility of bacteria isolated from urine samples obtained from nursing home residents. Infect Control Hosp Epidemiol. 2009;30(11):1116-1119. 35. Vogel T, Verreault R, Gourdeau M, Morin M, Grenier-Gosselin L, Rochette L. Optimal duration of antibiotic therapy for uncomplicated urinary tract infection in older women: a double-blind randomized controlled trial. CMAJ. 2004;170(4):469-473. 36. Jepson RG, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2008;(1):CD001321. 37. Burgio KL, Newman DK, Rosenberg MT, Sampselle C. Impact of behaviour and lifestyle on bladder health. Int J Clin Pract. 2013;67(6):495-504. 38. Loeb M, Bentley DW, Bradley S, et al. Development of minimum criteria for the initiation of antibiotics in residents of long-term-care facilities: results of a consensus conference. Infection Control and Hospital Epidemiology. 2001; 22(2):120-124. Joan M. Nelson University of Colorado at Anshutz Medical Campus College of Nursing, Aurora, Colo. Elliot Good is an adult-geriatric NP at Physician Housecalls, Wheat Ridge, Colo. The authors would like to thank Jason Weiss, Research Coordinator, Office of Research and Scholarship, University of Colorado at Anshutz Medical Center, for his help with editing and formatting of this manuscript.
32. Hooton TM, Stamm WE. Diagnosis and treatment of uncomplicated urinary tractinfection. Infect Dis Clin North Am 1997; 11:551–581.
The authors have disclosed that they have no financial relationships related to this article.
33. Infectious Diseases Society of America. Infections by organ system. 2013. http://www.idsociety.org/Organ_System.
DOI-10.1097/01.NPR.0000460855.44987.c1
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rinary tract infections (UTIs) are some of the most commonly diagnosed bacterial infections in older adults and pose a significant clinical and financial burden to patients and healthcare providers alike.1 Symptomatic UTI is defined as the presence of bacteria in the urine at defined quantitative levels (generally 105 colony forming units per milliliter [CFU/mL]), with concomitant symptoms attributable to the genitourinary tract, such as dysuria, frequency, urgency, and flank or suprapubic pain.2 It is important to accurately identify UTI in older adults to
U
avoid complications, such as falls, sepsis, and death.3-5 However, diagnosis is often complicated by communication difficulties and cognitive impairment in this population, and clinicians frequently rely on urinalysis to diagnose infections.6 This is not an accurate method of diagnosis due to the prevalence of asymptomatic bacteriuria (ASB) in older adults.1,7 Urine culture should instead be used to guide antibiotic selection in the presence of UTI symptoms.6 ASB is defined as the presence of bacteriuria on microscopy or in urine culture from a patient who does not
Keywords: asymptomatic bacteriuria, older adults, urinary tract infection
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The Nurse Practitioner • August 2015 43
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Rob Byron / Shutterstock ©
By Joan M. Nelson, DNP, ANP and Elliot Good, MS, AGNP
Urinary tract infections and asymptomatic bacteriuria in older adults
have symptoms attributable to the genitourinary tract.8 The incidence of ASB increases with age to nearly 20% of community-dwelling women and 15% of communitydwelling men over the age of 75. 8 This number is even higher in long-term care facilities, where nearly 50% of female residents and 40% of male residents have ASB.9 Symptomatic UTIs occur relatively infrequently in comparison, with a point-prevalence rate estimated at 1.1%.10 Unfortunately, the diagnosis of UTI is often made in the setting of a positive urine culture and absence of a positive clinical history of genitourinary symptoms, resulting in misdiagnosis and overtreatment.8,11,12 ■ Testing and treatment Testing and treatment of ASB is not recommended in the general older-adult population, as it has not been shown to reduce risk and may instead contribute to poor outcomes.9,11 Randomized controlled trials have shown that treatment of ASB may, in fact, increase the risk of developing symptomatic UTI.7 In addition, treating ASB does not improve incontinence rates, reduce the risk of recolonization of the urinary tract, or lower the rate of hospitalization and death.8 Instead, the inappropriate treatment of ASB contributes to the overuse of antibiotics, which is a well-recognized problem among older adults. Antibiotic treatment can have profound effects on natural intestinal flora and lead to the development of antibiotic-associated diarrhea, including Clostridium difficile infection and pseudomembranous colitis, which are leading causes of morbidity and mortality in older patients.11,13 In addition, inappropriate antibiotic-prescribing practices have contributed to the growing emergence of antibiotic-resistant organisms, which complicate therapeutic options, lead to greater illness, and increase cost of treatment. 14 Escherichia coli (E. coli), the bacterium most frequently implicated in UTI, is becoming increasingly
suffering, increases cost to the healthcare system, and is a significant public-health concern that warrants both close attention to prescribing practices and careful adherence to medication regimens. When a symptomatic UTI does warrant treatment, the judicious choice of a narrow-spectrum antibiotic, guided by local antibiograms, can further reduce the risk of unnecessary antibiotic exposure and the development of antimicrobial resistance.8,11,14 Clinicians must avoid the empirical use of broad-spectrum antibiotics in the treatment of UTI.11,16 Despite the strong evidence against treatment of ASB, studies have suggested that, in practice, patients often get treated for bacteriuria in the absence of urinary symptoms.8,9 In fact, one-third to one-half of patients who test positive for ASB receive antibiotic treatment.16,17 Reasons for treatment include the diagnostic challenges posed by the sometimes vague presentation of UTI in the older adult.18 Several diagnostic algorithms aimed at preventing the inappropriate treatment of ASB have been developed, and studies have shown that implementation of antibioticstewardship programs can have a positive effect on the reduction of overtreatment of ASB and improve patient outcomes.19-21 However, treatment of ASB is still common, and increased quality measures are needed to raise clinical practice to the level of evidence-based standards in the diagnosis and management of UTI.9,11
■ Etiology In the younger-adult population, UTI occurs significantly more often among women than among men.1 Reasons include the proximity of the urethral opening in women to the perianal area and the relative ease of bacterial migration. The female urethra is also shorter in length, which eases bacterial transit to the bladder. UTI in the younger adult male is rare and is usually related to some degree of anatomical abnormality or immunological defect.22 As they age, both men and women face increased prevalence of ASB and symptomatic The incidence of ASB increases to nearly 20% UTI. There are a number of physiologic, cognitive, and behavioral reasons for of community-dwelling women and 15% of this increase. Neurologic abnormalities, community-dwelling men over age 75. such as Alzheimer disease, Parkinson disease, or cerebrovascular disease can result in impaired bladder emptying, urinary retention, and incontinence, which can require resistant to first-line antibiotic treatment. Patients infected 6 catheterization. The use of catheters and urine-collection with antibiotic-resistant strains of E. coli are more likely to be hospitalized and are at greater risk of complication and devices can introduce bacteria into the bladder. Patients with death from infection.15 When pathogens become resistant diabetes mellitus, particularly those with poor glycemic control, are also at greater risk.23 Urological conditions that to first-line treatment, second- and third-line treatments must be used and are often less effective, more toxic, and result in obstruction of urine flow, such as urolithiasis or more expensive.11 Antibiotic resistance worsens patient tumor, lead to urine stasis and growth of bacteria.6
44 The Nurse Practitioner • Vol. 40, No. 8
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Urinary tract infections and asymptomatic bacteriuria in older adults
As postmenopausal women experience a loss of estrogen, the pH of the vaginal and urethral tissues rises, thus, reducing lactobacillus levels and increasing susceptibility to bacterial colonization.24 Cystoceles are associated with an increase in recurrent UTI related to a rise in post-void residual. In addition, impaired voiding patterns and changes in hygiene increase the risk of UTI in older women.6 Older male patients are at increased risk for UTI related to the development of benign prostatic hyperplasia (BPH) and bladder retention. 2 The prevalence of BPH increases with age so that 60% of 60-year olds and over 80% of 80-year-old males have this condition.25 A lifetime history of UTI is also a significant predictor of UTIs in later life.1
Proteus mirabilis, Pseudomonas aeruginosa, Klebsiella, yeast, and Enterobacter.1 ■ Clinical presentation Lower UTIs are confined to either the bladder (cystitis) or the urethra (urethritis) and often present with dysuria, frequency, urgency, and occasionally, suprapubic tenderness. UTIs involving the upper urinary tract and kidneys (pyelonephritis) are accompanied by more severe symptoms, such as fever, chills, nausea, vomiting, and flank pain.26 Older adults with cognitive dysfunction are, unfortunately, often unable to accurately report these symptoms. UTIs can lead to serious complications. Up to 8% of falls in residential care facilities were linked to symptomatic UTIs in one study, perhaps due to the presence of urinary urgency and frequency.5 Gau and colleaues reported falls in 24% of hospitalized older adults with UTI versus only 4% of those with ASB.4 About 5% of cases of sepsis are caused by UTIs.27 Risk factors for the development of sepsis from a UTI include female gender, structural or functional condition that obstructs the flow of urine, impaired immunity, or comorbid disease.27 Because of the importance of correctly distinguishing UTI from ASB, a minimum set of criteria to guide urinalysis-ordering in long-term care settings, the McGeer criteria was identified/
■ Pathogenesis Urine is normally sterile but can become a good medium for growth when bacteria invade the bladder and are not eliminated. The most common means of bacterial entry into the urinary tract is ascension from the urethral opening.2 Bacteria are normally present around the urethral opening in both men and women, and the lower third of the urethra is frequently contaminated with bacteria.1 These bacteria are normally flushed out with micturition and do not ascend far enough to cause symptoms. The female urethra is relatively short and proximal to the vagina and rectum, which have abundant microbial Lower UTIs are confined to either the bladder or communities. In the presence of an anatomical or functional abnormality—or the urethra and present with dysuria, frequency, following sexual activity, urethral masurgency, and occasionally, suprapubic tenderness. sage, or catheterization—bacteria travel up the urethra toward the bladder and upper urinary tract structures.6 In men, developed in 1989 and updated/revised 11 years later by prostatic hypertrophy contributes to urinary retention and Loeb.28,29 These infection-surveillance definitions were impaired voiding patterns, which lead to urine stasis and the 2 subsequent growth of bacteria. developed for long-term care residents who had impaired cognition and functional status or required skilled nursing The most commonly isolated organism in 80% to 90% care.30 These criteria were reviewed and updated in 2009 of ASB and symptomatic UTI is Gram-negative, uropatho1 genic E. coli. These uropathogenic strains of E. coli are based on a literature review and updated consensus opinions.30 Change in urine characteristics, which had been different from the strains that normally colonize the gastrointestinal tract in that they have enhanced ability to included in both the original McGeer and Loeb criteria, colonize the urinary tract and evade the host’s immune was removed from the updated recommendations because response. For example, uropathogenic E. coli have virulence it does not distinguish UTI from ASB. Likewise, altered factors that enhance fimbrial adhesions to urethral mental status, which was one of the Loeb criteria, was epithelial tissue, facilitating the establishment and persisfound poorly to distinguish true infection from ASB and tence of colonization. These strains of E. coli are highly has been removed from the updated criteria. This update heterogeneous, and as of yet, there is no test available to emphasizes the need to ensure that symptoms of UTI are determine E. coli uropathogenicity unless the sample is new or worsened, alternative explanations for the signs and obtained directly from the urinary tract. Other than E. symptoms are evaluated, and microbiologic and clinical coli, the remaining 10% to 20% of UTIs are caused by evidence are combined in making a diagnosis of infection.30 microorganisms such as Staphylococcus saprophyticus, (See The updated UTI-surveillance criteria.) www.tnpj.com
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Urinary tract infections and asymptomatic bacteriuria in older adults
McGeer and Loeb criteria have been widely adopted for use in long-term care, but they remain merely expert opinion without much supporting evidence. JuthaniMehta and colleagues correlated clinical symptoms with microbiologic findings of bacteriuria and pyuria, reporting sensitivities of both the original McGeer criteria and the Loeb criteria to be poor (McGeer 30%, Loeb 19%).31 Falsepositive tests were uncommon, but specificity was likely overestimated because lab testing is a poor gold standard for infection. Most of these criteria rely on older adults’ reports of subjective symptoms; however, this information is not obtainable in older adults who are cognitively impaired, and it is difficult to assess in those with underlying urinary incontinence. The updated UTI-surveillance criteria30 The updated UTI-surveillance criteria require the following for diagnosis of UTI in patients without an indwelling catheter: At least one of the following signs or symptoms: • Acute dysuria or acute pain, swelling, or tenderness of the testes, prostate, or epididymis • Fever or leukocytosis AND at least one of the following - Acute costovertebral angle (CVA) tenderness or pain - Suprapubic pain - Gross hematuria - Marked increase in or new-onset incontinence, urinary urgency, or frequency OR • If no fever or leukocytosis, at least two of the following: - Suprapubic pain - Hematuria - Marked increase in or new-onset incontinence, urinary urgency, or frequency AND • At least 105 CFU/mL of no more than two species of bacteria in a voided urine specimen • At least 102 CFU/mL of any number of microorganisms in a straight catheter-obtained urine sample Patients with urinary catheters must demonstrate at least one of the following: • Fever, chills, or new-onset hypotension without alternate site of infection • Acute change in mental status or functional decline AND leukocytosis without alternate site of infection • New-onset suprapubic pain or CVA pain/tenderness • Purulent discharge from the catheter site OR acute pain, swelling, or tenderness in the testes, prostate, or epididymis AND • At least 105 CFU/mL of any organism cultured from catheter specimen after replacement of catheter if it has been in place for more than 2 weeks.
■ Diagnostic testing UTIs are frequently classified according to location, presence or absence of complicating factors, and frequency of infection. A complicated UTI is an infection that occurs in the presence of an underlying condition that increases the risk of therapeutic failure.8 The majority of the time, cystitis and pyelonephritis in an otherwise healthy woman are considered uncomplicated, though some regard older female patients as complicated due to functional or structural abnormalities of the urinary tract that are common in this population.8 UTIs in men have traditionally been considered complicated, but recently, it has been acknowledged that healthy men can occasionally develop acute, uncomplicated UTIs (most often related to anal intercourse).32 The diagnosis of recurrent UTI is made following two or more infections in 6 months or three or more infections in 1 year. For uncomplicated lower UTIs, there is no evidence that recurrence leads to chronic health problems, including kidney disease.6 Recurrent pyelonephritis is uncommon. When urine is tested in asymptomatic patients and found to be contaminated with bacteria, a diagnosis of ASB is made. The diagnosis of ASB for noncatheterized older women is based on a culture of two consecutive clean, midstream catches of urine that demonstrate bacterial counts of greater than 10 5 CFU/mL of the same organism. Men require only one urinary sample with this quantity of a single bacterial organism to be diagnosed with ASB.8 Lab data are ineffective in distinguishing ASB from UTI because bacterial counts, cultures, and the presence of pyuria do not distinguish between these conditions.8 Pyuria, without infection, is present in 90% of institutionalized older adults. E. coli is the most common organism associated with the urinary tract and is found in both UTIs and ASB. Urine dipstick testing has been found to be of little value in the diagnosis of UTI in older adults.6 The positive and negative predictive values of urine dipstick tests are no better than those based on evaluation of clinical symptoms using either Loeb or McGeer criteria.6 The use of urine culture combined with assessment of clinical symptoms is the best way to diagnose UTI in older adults.8 ■ Treatment The Infectious Disease Society of America has developed guidelines for treatment of uncomplicated UTI in women, catheter-associated UTI, and ASB.33 The uncomplicatedUTI guideline (which specifically excludes postmenopausal women) recommends trimethoprim-sulfamethoxazole (TMP-SMX), nitrofurantoin, and fosfomycin as first-line empiric therapies for uncomplicated infections.33
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Urinary tract infections and asymptomatic bacteriuria in older adults
E. coli species cultured from long-term care residents have acquired a great deal of resistance to many of the antibiotics used to treat UTIs in practice.34 Twenty-five percent of isolates from this population were resistant to TMP-SMX, and 60% were resistant to fluoroquinolones.34 More than 90% of organisms were susceptible to nitrofurantoin, but use of this medication is limited to adults with a glomerular filtration rate greater than 60.34 To minimize development of antibiotic resistance, narrow-spectrum antibiotics should be used to treat infection, and the choice of the agent should be guided by the urine culture and antibiograms, which show local patterns of microbial resistance. Three days of therapy for infection in older women has been shown to be sufficient.35 Prevention of recurrence is an important part of the treatment plan. Daily intake of cranberry juice or tablets may be effective in helping to prevent UTIs, especially in cases of recurrent infection, though the exact strength of the tablet or amount of juice required has not been established.36 Vaginal estrogen and increasing fluid consumption have been found to prevent UTI recurrence in postmenopausal women.24,37 Good perineal care and frequent changing of incontinence briefs can reduce the incidence of UTIs because skin chafing and rashes compromise an important barrier to infection and because fecal soiling introduces infectious organisms to the urinary tract. This article has focused on noncatheter-associated UTI, but the use of indwelling catheters poses a high risk for UTI. Catheterization should be avoided when possible, and duration of use should be limited. ■ Implications for practice Pharmaceutical companies have dramatically slowed development of new antibiotics, yet antibiotic resistance to pathogens is increasing.14 UTIs are one of the leading causes of antibiotic use among older adults and are associated with the development of sepsis from a UTI and hospitalizations.9 On the other hand, the prevalence of ASB ranges from 23% to 50% in institutionalized older adults.38 Mistaking ASB for symptomatic UTI can lead to inappropriate antibiotic use and increased risk for C. difficile infection, drug allergies/adverse drug reactions, and antibiotic resistance. This article focused on older adults, especially those living in long-term care facilities, because this population has very high rates of ASB and is most at risk for complications developing from antibiotic overuse. One-third of antibiotic prescriptions for a presumed UTI are actually given inappropriately for ASB.38 Implementation of UTI-surveillance criteria can help decrease inappropriate use of antibiotics by at least 30%.38 Appropriate selection of antibiotic therapies and duration of www.tnpj.com
treatment can further help to avoid infection recurrence and multiple drug resistance. REFERENCES 1. Foxman B. The epidemiology of urinary tract infection. Nat Rev Urol. 2010; 7(12):653-660. 2. Genao L, Buhr GT. Urinary tract infections in older adults residing in longterm care facilities. Ann Longterm Care. 2012;20(4):33-38. 3. Søgaard M, Sch¯nheyder HC, Riis A, S¯rensen HT, N¯rgaard M. Short-term mortality in relation to age and comorbidity in older adults with communityacquired bacteremia: a population-based cohort study. J Am Geriatr Soc. 2008; 56(9):1593-1600. 4. Gau JT, Shibeshi MR, Lu IJ, et al. Interexpert agreement on diagnosis of bacteriuria and urinary tract infection in hospitalized older adults. J Am Osteopath Assoc. 2009;109(4):220-226. 5. Kallin K, Jensen J, Olsson LL, Nyberg L, Gustafson Y. Why the elderly fall in residential care facilities, and suggested remedies. J Fam Pract. 2004;53(1): 41-52. 6. Beveridge LA, Davey PG, Phillips G, McMurdo ME. Optimal management of urinary tract infections in older people. Clin Interv Aging. 2011;6:173-180. 7. Bengtsson C, Bengtsson U, Bjˆrkelund C, Lincoln K, Sigurdsson JA. Bacteriuria in a population sample of women: 24-year follow-up study. Results from the prospective population-based study of women in Gothenburg, Sweden. Scand J Urol Nephrol. 1998;32(4):284-289. 8. Nicolle LE, Bradley S, Colgan R, Rice JC, Schaeffer A, Hooton TM. Infectious Diseases Society of America guidelines for the diagnosis and treatment of asymptomatic bacteriuria in adults. Clin Infect Dis. 2005;40 (5):643-654. 9. Lin K, Fajardo K, Force USPST. Screening for asymptomatic bacteriuria in adults: evidence for the U.S. Preventive Services Task Force reaffirmation recommendation statement. Ann Intern Med. 2008;149(1):W20-W24. 10. Tsan L, Davis C, Langberg R, et al. Prevalence of nursing home-associated infections in the Department of Veterans Affairs nursing home care units. Am J Infect Control. 2008;36(3):173-179. 11. Gross PA, Patel B. Reducing antibiotic overuse: a call for a national performance measure for not treating asymptomatic bacteriuria. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2007;45(10):1335-1337. 12. Woodford HJ, George J. Diagnosis and management of urinary tract infection in hospitalized older people. J Am Geriatr Soc. 2009;57(1):107-114. 13. Dethlefsen L, Huse S, Sogin ML, Relman DA. The pervasive effects of an antibiotic on the human gut microbiota, as revealed by deep 16S rRNA sequencing. PLoS Biol. 2008;6(11):e280. 14. Spellberg B, Guidos R, Gilbert D, et al. The epidemic of antibiotic-resistant infections: a call to action for the medical community from the Infectious Diseases Society of America. Clin Infect Dis. 2008;46(2):155-164. 15. Hoban DJ, Nicolle LE, Hawser S, Bouchillon S, Badal R. Antimicrobial susceptibility of global inpatient urinary tract isolates of Escherichia coli: results from the Study for Monitoring Antimicrobial Resistance Trends (SMART) program: 2009-2010. Diagnostic microbiology and infectious disease. 2011;70(4):507-511. 16. McMurdo ME, Gillespie ND. Urinary tract infection in old age: overdiagnosed and over-treated. Age Ageing. 2000;29(4):297-298. 17. Nicolle LE. Asymptomatic bacteriuria: when to screen and when to treat. Infect Dis Clin North Am. 2003;17(2):367-394. 18. Chant C, Dos Santos CC, Saccucci P, Smith OM, Marshall JC, Friedrich JO. Discordance between perception and treatment practices associated with intensive care unit-acquired bacteriuria and funguria: a Canadian physician survey. Crit Care Med. 2008;36(4):1158-1167. 19. Buhr GT, Genao L, White HK. Urinary tract infections in long-term care residents. Clin Geriatr Med. 2011;27(2):229-239. 20. Chowdhury F, Sarkar K, Branche A, et al. Preventing the inappropriate treatment of asymptomatic bacteriuria at a community teaching hospital. J Community Hosp Intern Med Perspect. 2012;2(2). 21. File TM Jr., Solomkin JS, Cosgrove SE. Strategies for improving antimicrobial use and the role of antimicrobial stewardship programs. Clin Infect Dis. 2011;53(suppl 1):S15-S22. 22. Griebling T. Urinary tract infection in men. In: Disease NIoDaDaK, ed. Urologic Diseases in America. Washington, DC: Government Printing Office; 2007.
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Urinary tract infections and asymptomatic bacteriuria in older adults
23. Zhanel GG, Nicolle LE, Harding GK. Prevalence of asymptomatic bacteriuria and associated host factors in women with diabetes mellitus. The Manitoba Diabetic Urinary Infection Study Group. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 1995;21(2):316-322. 24. Perrotta C, Aznar M, Mejia R, Albert X, Ng CW. Oestrogens for preventing recurrent urinary tract infection in postmenopausal women. Cochrane Database Syst Rev. 2008;(2):CD005131. 25. Cunningham G, Kadmon D. Epidemiology and pathogenesis of benign prostatic hypertrophy. http://www.uptodate.com/contents/epidemiologyand-pathogenesis-of-benign-prostatic-hyperplasia. 26. McCance KL HS, Brashers VL, Rote NS. Pathophysiology: The Biological Basis for Disease in Adults and Children. 6th ed. Maryland Heights, MO: Elsevier; 2010. 27. Kalra OP, Raizada A. Approach to a patient with urosepsis. J Glob Infect Dis. 2009;1(1):57-63. 28. McGeer A. Definitions of infection for surveillance in long-term care facilities. 1996. https://www.premierinc.com/safety/topics/guidelines/ downloads/25_itcdefs-91.pdf. 29. Tal S, Guller V, Levi S, et al. Profile and prognosis of febrile elderly patients with bacteremic urinary tract infection. J Infect. 2005;50(4):296-305. 30. Stone, ND. Surveillance definitions of infections in long-term care facilities: revisiting the McGeer Criteria. Infection Control Hospital Epidemiology. 2012;33(10):965-977. 31. Juthani-Mehta M, Tinetti M, Perrelli E, Towle V, Van Ness PH, Quagliarello V. Diagnostic accuracy of criteria for urinary tract infection in a cohort of nursing home residents. J Am Geriatr Soc. 2007;55(7):1072-1077.
34. Das R, Perrelli E, Towle V, Van Ness PH, Juthani-Mehta M. Antimicrobial susceptibility of bacteria isolated from urine samples obtained from nursing home residents. Infect Control Hosp Epidemiol. 2009;30(11):1116-1119. 35. Vogel T, Verreault R, Gourdeau M, Morin M, Grenier-Gosselin L, Rochette L. Optimal duration of antibiotic therapy for uncomplicated urinary tract infection in older women: a double-blind randomized controlled trial. CMAJ. 2004;170(4):469-473. 36. Jepson RG, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev. 2008;(1):CD001321. 37. Burgio KL, Newman DK, Rosenberg MT, Sampselle C. Impact of behaviour and lifestyle on bladder health. Int J Clin Pract. 2013;67(6):495-504. 38. Loeb M, Bentley DW, Bradley S, et al. Development of minimum criteria for the initiation of antibiotics in residents of long-term-care facilities: results of a consensus conference. Infection Control and Hospital Epidemiology. 2001; 22(2):120-124. Joan M. Nelson University of Colorado at Anshutz Medical Campus College of Nursing, Aurora, Colo. Elliot Good is an adult-geriatric NP at Physician Housecalls, Wheat Ridge, Colo. The authors would like to thank Jason Weiss, Research Coordinator, Office of Research and Scholarship, University of Colorado at Anshutz Medical Center, for his help with editing and formatting of this manuscript.
32. Hooton TM, Stamm WE. Diagnosis and treatment of uncomplicated urinary tractinfection. Infect Dis Clin North Am 1997; 11:551–581.
The authors have disclosed that they have no financial relationships related to this article.
33. Infectious Diseases Society of America. Infections by organ system. 2013. http://www.idsociety.org/Organ_System.
DOI-10.1097/01.NPR.0000460855.44987.c1
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