Asymptomatic bacteriuria in nursing home patients

Asymptomatic bacteriuria in nursing home patients

This learning project was stimulated by an article (1) which looked at why urine cultures are ordered and why antibiotics are prescribed for institutionalized elderly. The article concluded that because there was no evidence for an association between nonspecific signs and symptoms and the presence or absence of bacteriuria, using those nonspecific signs and symptoms as the basis for ordering cultures and antibiotics is not warranted. The authors base this on two articles (2, 3).

Looking at the abstracts for these two articles is instructive. Whereas the nonspecific signs and symptoms reported by nurses and physicians in the Walker study were typically based on observation of the residents who frequently have cognitive impairment and are unable to articulate their symptoms, the Boscia study questioned patients about both specific and nonspecific symptoms such as anorexia, difficulty in falling asleep, difficulty in staying asleep, fatigue, malaise, weakness. Such self-reported symptoms may have little to do with observations of increased restlessness or confusion, irritability, crying, aggression, agitation, uncooperativeness, falling, or eating less that were identified by the Walker study clinicians.

The Berman paper involved institutionalized elderly veterans. They looked carefully for signs of infection when there was functional decline, and in fact found infection (and we assume treated those infections) in 50 out of 65 instances of functional decline during the 6-month surveillance period. The death rate dropped during the 6 months and returned to baseline afterwards, which supports the idea that looking for and treating infection is a good idea when there is functional decline. It should be noted that the Walker article refers to the infections in the Berman study as being urinary tract infections, but the type of infection is not mentioned in the title or abstract of the Berman paper.

The Walker paper also refers to five studies which purport to provide “compelling evidence to support not treating asymptomatic bacteriuria in elderly residents of long-term care facilities” (4-8).

Let’s look at each of these articles in turn. The Boscia paper looked at elderly ambulatory nonhospitalized women, and showed that antibiotic therapy for nonsymptomatic bacteriuria halved the rate at which symptomatic UTI developed in the subsequent 6 months.

The Ouslander article studied nursing home residents with chronic urinary incontinence, who had otherwise asymptomatic bacteriuria. Eradication of the bacteriuria had no effect on the severity of the chronic incontinence.

The Abrutyn article looked at elderly ambulatory women in retirement communities without urinary catheters. An observational study using urine cultures every 6 months showed that infected residents had almost double the mortality rate compared to uninfected residents; however, infected residents were also older and sicker. The infected residents were divided into a treatment group and a no-treatment group; no mention is made in the abstract of randomization or of blinding, or of placebo controls. Nevertheless, although treated residents had a slightly lower mortality (13.8 per 100,000 vs 15.1 per 100,000) the difference was not statistically significant.

The Nicolle study on 50 institutionalized elderly women (I have the full article) found a high incidence (about 50%) of bacteriuria based on monthly urine cultures over 12 months. Half of the 50 women were randomly assigned to receive antibiotic treatment for positive urine cultures; the other half received no treatment, unless symptoms developed. The treated group had a rate of 0.67 incidents per patient-year of genitourinary morbidity, vs 0.92 for the no-therapy group (non-significant difference) but had a significantly higher rate of adverse drug effects. Nine of 23 treated patients died during the study year, compared to 4 of 22 untreated patients (non-significant difference). The study certainly demonstrates that there is no benefit to a protocol which screens all residents for bacteriuria regardless of symptoms, functional decline, or other triggers for testing, and then treats positive culture results. No benefit, and likely there is harm. But the study does not address outcomes if testing is based on whether there are clinical triggers such as increased confusion or falling.

Finally, the earlier Nicolle study which looked at all noncatheterized male residents on two geriatric wards over a 2-year period. Monthly urine samples were obtained. Positive cultures were treated with single doses of either trimethoprim/sulfamethoxazole or tobramycin. 36 of 88 men who had were re-infected or failed the single-dose treatment were randomized to either eradication therapy or no treatment. The rates of mortality and infectious morbidity were similar in the two groups. Again, this study is based on screening all residents rather than testing only residents where there is some justification for it.

Lindsay Nicolle is a very prolific writer: a medline search on her name and the term “bacteriuria” turned up 52 hits. However, there is only one additional study involving treatment in institutionalized elderly (9). This article appears to be a report on 26 of the patients previously reported in (7).

I failed to turn up any studies of treatment in institutionalized elderly who were found to be bacteriuric when testing was inititiated in response to nonspecific symptoms such as increased restlessness or confusion, irritability, crying, aggression, agitation, uncooperativeness, falling, or eating less.

I propose we do such a study, perhaps together with Maimonides, and making use of our new linkage with McGill.

Walker, S., A. McGeer, A. E. Simor, M. Armstrong-Evans, and M. Loeb (2000) CMAJ 163:273-277.

Why are antibiotics prescribed for asymptomatic bacteriuria in institutionalized elderly people? A qualitative study of physicians’ and nurses’ perceptions.

BACKGROUND: Antibiotic therapy for asymptomatic bacteriuria in institutionalized elderly people has not been shown to be of benefit and may in fact be harmful; however, antibiotics are still frequently used to treat asymptomatic bacteriuria in this population. The aim of this study was to explore the perceptions, attitudes and opinions of physicians and nurses involved in the process of prescribing antibiotics for asymptomatic bacteriuria in institutionalized elderly people. METHODS: Focus groups were conducted among physicians and nurses who provide care to residents of long-term care facilities in Hamilton, Ont. A total of 22 physicians and 16 nurses participated. The focus group discussions were tape-recorded, and the transcripts of each session were analysed for issues and themes emerging from the text. Content analysis using an open analytic approach was used to explore and understand the experience of the focus group participants. The data from the text were then coded according to the relevant and emergent themes and issues. RESULTS: We observed that the ordering of urine cultures and the prescribing of antibiotics for residents with asymptomatic bacteriuria were influenced by a wide range of nonspecific symptoms or signs in residents. The physicians felt that the presence of these signs justified a decision to order antibiotics. Nurses played a central role in both the ordering of urine cultures and the decision to prescribe antibiotics through their awareness of changes in residents’ status and communication of this to physicians. Education about asymptomatic bacteriuria was viewed as an important priority for both physicians and nurses. INTERPRETATION: The presence of non-urinary symptoms and signs is an important factor in the prescription of antibiotics for asymptomatic bacteriuria in institutionalized elderly people. However, no evidence exists to support this reason for antibiotic treatment. Health care providers at long-term care facilities need more education about antibiotic use and asymptomatic bacteriuria.

Berman, P., D. B. Hogan, and R. A. Fox (1987) Age Ageing 16:201-207.

The atypical presentation of infection in old age.

A study was designed to determine the incidence of atypical or geriatric presentation of infection in a long-term-care-hospital population of aged veterans. During the 6-month period of surveillance there were 65 instances of functional decline among the 143 veterans, with 50 episodes of infection. Although the symptoms and signs of infection were attenuated in many patients, a diagnosis was reached by careful examination and investigation. The majority of patients had a temperature of at least 38 degrees C in the presence of infection and it is concluded that the afebrile response to infection is rare in this population. During the course of this study the death rate in this institution dropped to about half of what was anticipated, and returned to previous levels following completion of the study. Infection can be recognized at a very early stage despite an atypical geriatric presentation and early treatment reduces morbidity and mortality.

Boscia, J. A., W. D. Kobasa, E. Abrutyn, M. E. Levison, A. M. Kaplan, and D. Kaye (1986) Am J Med 81:979-982.

Lack of association between bacteriuria and symptoms in the elderly.

In a study of bacteriuria in elderly (mean age 85 years, range 69 to 101), mostly middle- and upper-class Jewish subjects, attempts were made to determine if bacteriuria without dysuria is otherwise asymptomatic. Seventy-two subjects (59 women and 13 men) without dysuria were questioned about other urinary symptoms (incontinence, frequency, urgency, suprapubic pain, flank pain, fever) and symptoms indicating a lack of well-being (anorexia, difficulty in falling asleep, difficulty in staying asleep, fatigue, malaise, weakness) when they were with and without bacteriuria. Twenty-two subjects had bacteriuria that resolved spontaneously; bacteriuria subsequently developed in 24 nonbacteriuric subjects; and 26 subjects had bacteriuria that resolved with antimicrobial therapy. Subjects occasionally reported urinary symptoms (especially incontinence) and commonly reported symptoms indicating a lack of well-being when they were with and/or without bacteriuria. However, no differences in symptoms were found when bacteriuric subjects were compared with themselves when they were nonbacteriuric. Thus, bacteriuria without dysuria in the elderly appears to be asymptomatic.

Boscia, J. A., W. D. Kobasa, R. A. Knight, E. Abrutyn, M. E. Levison, and D. Kaye (1987) JAMA 257:1067-1071.

Therapy vs no therapy for bacteriuria in elderly ambulatory nonhospitalized women.

This prospective randomized study was undertaken to determine the efficacy of antimicrobial therapy compared with no therapy for bacteriuria in elderly ambulatory nonhospitalized women. Sixty-one women (mean age, 85.8 years) with bacteriuria were in the no therapy control group and 63 women (mean age, 85.8 years) with bacteriuria were in the therapy group; none had symptoms of urinary tract infection. One short course of antimicrobial therapy achieved a cure rate of 68.3% (43 of 63 women cured) two weeks after treatment. During the six-month follow-up period, ten (16.4%) of 61 women in the no therapy group and five (7.9%) of 63 women in the therapy group developed symptomatic urinary tract infection. At the time of six-month follow-up, 19 (34.5%) of 55 women in the no therapy group and 35 (63.6%) of 55 women in the therapy group did not have bacteriuria. We conclude that for asymptomatic bacteriuria in elderly ambulatory nonhospitalized women, short-course antimicrobial therapy is effective at two-week follow-up and that antimicrobial therapy can eliminate bacteriuria in most of these women for at least a six-month period.

Ouslander, J. G., M. Schapira, J. F. Schnelle, G. Uman, S. Fingold, E. Tuico, and J. G. Nigam (1995) Ann Intern Med 122:749-754.

Does eradicating bacteriuria affect the severity of chronic urinary incontinence in nursing home residents?

OBJECTIVE: To determine the effects of eradicating otherwise asymptomatic bacteriuria on the severity of chronic urinary incontinence among nursing home residents. DESIGN: Residents were categorized as nonbacteriuric or bacteriuric on the basis of urine cultures. Bacteriuric residents were then randomly assigned to immediate and delayed treatment groups. The delayed treatment group was included to control for spontaneous changes in the severity of incontinence. The immediate treatment group received antimicrobial therapy for 7 days; after outcome measures had been repeated, the delayed treatment group was treated. SETTING: 6 community-based nursing homes. PATIENTS: Nursing home residents with chronic urinary incontinence. MEASUREMENTS: The frequency and volume of urinary incontinence were determined by physical checks for wetness by trained research aides hourly between 7 a.m. and 7 p.m. for 3 days in all patient groups (non-bacteriuric, bacteriuric with immediate treatment, and bacteriuric with delayed treatment) at baseline, after the immediate treatment group was treated, and again after the delayed treatment group was treated. RESULTS: 191 residents were enrolled, and 176 completed the study. Bacteriuria was eradicated by antimicrobial therapy in 71 residents (40%), and 17 residents (10%) had bacteriuria before and after therapy. The percentage of hourly checks at which the residents were found wet and other measures of incontinence severity remained essentially the same after bacteriuria was eradicated. In the nonbacteriuric group, the percentage of checks that were wet increased from 29% (95% CI, 26% to 32%) at baseline to 30% (CI, 27% to 34%) on repeated measurement. In the bacteriuric groups, the percentage increased from 34% (CI, 30% to 38%) before treatment to 35% (CI, 31% to 39%) after bacteriuria was eradicated. The presence of pyuria did not affect the results. CONCLUSION: Eradicating bacteriuria has no short-term effects on the severity of chronic urinary incontinence among nursing home residents. Our data support the practice of not treating asymptomatic bacteriuria in this population and validate the recommendations in the Health Care Financing Administration’s Resident Assessment Protocol for urinary incontinence.

Abrutyn, E., J. Mossey, J. A. Berlin, J. Boscia, M. Levison, P. Pitsakis, and D. Kaye (1994) Ann Intern Med 120:827-833.

Does asymptomatic bacteriuria predict mortality and does antimicrobial treatment reduce mortality in elderly ambulatory women?

OBJECTIVE: To determine whether asymptomatic bacteriuria in elderly ambulatory women is a marker of increased mortality and, if so, whether it is because of an association with other determinants of mortality or because asymptomatic bacteriuria is itself an independent cause, the removal of which might improve longevity. DESIGN: A cohort study and a controlled clinical trial of the effect of antimicrobial treatment. SETTING: A geriatric center and 21 continuing care retirement communities. PARTICIPANTS: Women without urinary tract catheters. MEASUREMENTS: Urine cultures every 6 months (the same organism at 10(5) colony-forming units or more per mL on two midstream urine specimens defined asymptomatic bacteriuria), comorbidity, and mortality. RESULTS: In the observational study, infected residents (n = 318) were older, and sicker, and had higher mortality (18.7 per 100,000 resident-days) than uninfected residents (n = 1173; 10.1 per 100,000 resident-days). However, in a multivariate Cox analysis, infection was not related to mortality (relative risk, 1.1; P > 0.2), whereas age at entry and self-rated health (score 1 [excellent] to 4 [bad or poor]) were strong predictors. In the clinical trial, mortality in 166 treated residents (13.8 per 100,000 resident-days) was comparable to that of 192 untreated residents (15.1 per 100,000 resident-days); the relative rate was 0.92 (95% CI, 0.57 to 1.47). The cure rates among treated and untreated residents were 82.9% and 15.6%, respectively. CONCLUSION: Urinary tract infection was not an independent risk factor for mortality, and its treatment did not lower the mortality rate. Screening and treatment of asymptomatic bacteriuria in ambulatory elderly women to decrease mortality do not appear warranted.

Nicolle, L. E., W. J. Mayhew, and L. Bryan (1987) Am J Med 83:27-33.

Prospective randomized comparison of therapy and no therapy for asymptomatic bacteriuria in institutionalized elderly women.

Fifty elderly (mean age, 83.4 +/- 8.8 years) institutionalized women with asymptomatic bacteriuria were randomly assigned either to receive therapy for treatment of all episodes of bacteriuria identified on monthly culture or to receive no therapy unless symptoms developed. Subjects were followed for one year. The therapy group had a mean monthly prevalence of bacteriuria 31 +/- 15 percent lower than those in the no-therapy group, but periods free of bacteriuria lasting six months or longer were documented for only five (24 percent) subjects. For residents receiving no therapy, 71 percent showed persistent infection with the same organism(s). Antimicrobial therapy was associated with an increased incidence of reinfection (1.67 versus 0.87 per patient-year) and adverse antimicrobial drug effects (0.51 versus 0.046 per patient-year) as well as isolation of increasingly resistant organisms in recurrent infection when compared with no therapy. No differences in genitourinary morbidity or mortality were observed between the groups. Thus, despite a lowered prevalence of bacteriuria, no short-term benefits were identified and some harmful effects were observed with treatment of asymptomatic bacteriuria. These data support current recommendations of no therapy for asymptomatic bacteriuria in this population.

Nicolle, L. E., J. Bjornson, G. K. Harding, and J. A. MacDonell (1983) N Engl J Med 309:1420-1425.

Bacteriuria in elderly institutionalized men.

Over a two-year period we obtained monthly urine samples from all noncatheterized male residents on two geriatric wards to determine the occurrence and optimal management of bacteriuria in this population. Among 88 men the prevalence of bacteriuria was 33 per cent, and the incidence was 45 infections per 100 patients per year. Outcomes after single-dose therapy for asymptomatic bacteriuria with 43 courses of trimethoprim/sulfamethoxazole and 23 of tobramycin included 15 cures, 40 relapses, and 11 treatment failures. Thirty-six residents who had a relapse or in whom single-dose therapy failed were randomly assigned to receive therapy to eradicate bacteriuria or to receive no therapy. All 20 residents who received no therapy remained bacteriuric. The 16 residents who received therapy had fewer months of bacteriuria after randomization, but at the end of the study only one remained free of bacteriuria. Mortality and infectious morbidity after randomization were similar in the two groups. These data suggest that asymptomatic bacteriuria is common in elderly institutionalized men and that therapy is neither necessary nor effective.

Nicolle, L. E., J. W. Mayhew, and L. Bryan (1988) Age Ageing 17:187-192.

Outcome following antimicrobial therapy for asymptomatic bacteriuria in elderly women resident in an institution.

Twenty-six elderly (mean age 83.3 +/- 8.7 years) institutionalized women with asymptomatic bacteriuria were treated with antibiotic therapy, including initial single-dose and subsequent 2 weeks’ therapy, then 6 weeks’ therapy if relapse occurred. Forty-seven courses of single-dose, 30 of 2 weeks’, and 10 of 6 weeks’ therapy were given during a 1-year period. At 8 weeks of follow-up, 57% of single-dose courses, 52% of 2-week, and 29% of 6-week had been followed by relapse, and 32%, 24%, and 29%, respectively, by reinfection. Outcome with single-dose therapy did not correlate with infecting organism, antimicrobial therapy, or presence of pyuria with the infection. However, residents who persistently relapsed following single-dose therapy appeared to be a less-well population, as evidenced by a significantly greater age, number of chronic disease diagnoses and medications, as compared to those who were cured by single-dose therapy. Thus, recurrent infection, including both relapse and reinfection is the usual short-term outcome following therapy for asymptomatic bacteriuria in this population. Differences in patient characteristics may prove useful in predicting which individuals may respond to minimal therapy.

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