Urinary immunoreactive interleukin-1 alpha and interleukin-6 in bacteriuric institutionalized elderly subjects

Atypical Presentation of Bacteremic Urinary Tract Infection in Older Patients: Frequency and Prognostic Impact

In older patients, urinary tract infection (UTI) often has an atypical clinical presentation, making its diagnosis difficult. We aimed to describe the clinical presentation in older inpatients with UTI-related bacteremia and to determine the prognostic impact of atypical presentation. This cohort study included all consecutive patients older than 75 years hospitalized in a university hospital in 2019 with a UTI-related gram-negative bacillus (GNB) bacteremia, defined by blood and urine cultures positive for the same GNB, and followed up for 90 days. Patients with typical symptoms of UTI were compared to patients with atypical forms. Among 3865 inpatients over 75 with GNB-positive urine culture over the inclusion period, 105 patients (2.7%) with bacteremic UTI were included (mean age 85.3 ± 5.9, 61.9% female). Among them, UTI symptoms were reported in only 38 patients (36.2%) and 44 patients (41.9%) had no fever on initial management. Initial diagnosis of UTI was made in only 58% of patient. Mortality at 90 days was 23.6%. After adjustment for confounders, hyperthermia (HR = 0.37; IC95 (0.14–0.97)) and early UTI diagnosis (HR = 0.35; IC95 (0.13–0.94)) were associated with lower mortality, while UTI symptoms were not associated with prognosis. In conclusion, only one third of older patients with UTI developing bacteremia had UTI symptoms. However, early UTI diagnosis was associated with better survival.

Asymptomatic Bacteriuria and Bacterial Interference

Asymptomatic bacteriuria is very common. In healthy women, asymptomatic bacteriuria increases with age, from <1% in newborns to 10% to 20% of women age 80 years, but is uncommon in men until after age 50 years. Individuals with underlying genitourinary abnormalities, including indwelling devices, may also have a high frequency of asymptomatic bacteriuria, irrespective of age or gender. The prevalence is very high in residents of long-term-care facilities, from 25% to 50% of women and 15% to 40% of men. Escherichia coli is the most frequent organism isolated, but a wide variety of other organisms may occur. Bacteriuria may be transient or persist for a prolonged period. Pregnant women with asymptomatic bacteriuria identified in early pregnancy and who are untreated have a risk of pyelonephritis later in pregnancy of 20% to 30%. Bacteremia is frequent in bacteriuric subjects following mucosal trauma with bleeding, with 5% to 10% of patients developing severe sepsis or septic shock. These two groups with clear evidence of negative outcomes should be screened for bacteriuria and appropriately treated. Asymptomatic bacteriuria in other populations is benign and screening and treatment are not indicated. Antimicrobial treatment has no benefits but is associated with negative outcomes including reinfection with antimicrobial resistant organisms and a short-term increased frequency of symptomatic infection post-treatment. The observation of increased symptomatic infection post-treatment, however, has led to active investigation of bacterial interference as a strategy to prevent symptomatic episodes in selected high risk patients.

Interleukin-6 concentrations in the urine and dipstick analyses were related to bacteriuria but not symptoms in the elderly: a cross sectional study of 421 nursing home residents

Background

Up to half the residents of nursing homes for the elderly have asymptomatic bacteriuria (ABU), which should not be treated with antibiotics. A complementary test to discriminate between symptomatic urinary tract infections (UTI) and ABU is needed, as diagnostic uncertainty is likely to generate significant antibiotic overtreatment. Previous studies indicate that Interleukin-6 (IL-6) in the urine might be suitable as such a test. The aim of this study was to investigate the association between laboratory findings of bacteriuria, IL-6 in the urine, dipstick urinalysis and newly onset symptoms among residents of nursing homes.

Methods

In this cross sectional study, voided urine specimens for culture, urine dipstick and IL-6 analyses were collected from all residents capable of providing a voided urine sample, regardless of the presence of symptoms. Urine specimens and symptom forms were provided from 421 residents of 22 nursing homes. The following new or increased nonspecific symptoms occurring during the previous month were registered; fatigue, restlessness, confusion, aggressiveness, loss of appetite, frequent falls and not being herself/himself, as well as symptoms from the urinary tract; dysuria, urinary urgency and frequency.

Results

Recent onset of nonspecific symptoms was common among elderly residents of nursing homes (85/421). Urine cultures were positive in 32% (135/421), Escherichia coli was by far the most common bacterial finding. Residents without nonspecific symptoms had positive urine cultures as often as those with nonspecific symptoms with a duration of up to one month. Residents with positive urine cultures had higher concentrations of IL-6 in the urine (p < 0.001). However, among residents with positive urine cultures there were no differences in IL-6 concentrations or dipstick findings between those with or without nonspecific symptoms.

Conclusions

Nonspecific symptoms among elderly residents of nursing homes are unlikely to be caused by bacteria in the urine. This study could not establish any clinical value of using dipstick urinalysis or IL-6 in the urine to verify if bacteriuria was linked to nonspecific symptoms.

Cytokines in urine in elderly subjects with acute cystitis and asymptomatic bacteriuria

OBJECTIVE

Searching for useful diagnostic tools to discriminate between asymptomatic bacteriuria (ASB) and acute cystitis, this study compared urinary levels of cytokines/chemokines and leukocyte esterase in three groups of elderly subjects; those with acute cystitis, those with ASB, and those without bacteriuria.

DESIGN

Comparative laboratory.

SETTING

Primary care.

SUBJECTS

A total of 16 patients with acute cystitis, 24 subjects with ASB, and 20 controls without bacteriuria, all of whom were aged 80 or over.

MAIN OUTCOME MEASURES

Urinary levels of IL-1 beta, TNF-alpha, IL-12, IL-18, CXCL1 (GRO-alpha), CXCL8 (IL-8), CCL2 (MCP-1), IL-6, IL-10, and leukocyte esterase.

RESULTS

Urinary levels of CXCL1, CXCL8, and IL-6 were significantly higher in acute cystitis patients than in the ASB group. The sensitivities and specificities for CXCL8, IL-6, and leukocyte esterase to discriminate between acute cystitis and ASB were 63% (95% CI 36-84) and 96% (95% CI 77-100) (cut-off > 285 pg/mg creatinine), 81% (95% CI 54-95) and 96% (95% CI 77-100) (cut-off > 30 pg/mg creatinine), and 88% (95% CI 60-98) and 79% (95% CI 57-92) (cut-off > 2, on a scale of 0-4), respectively.

CONCLUSIONS

The results indicate that measurement of urinary cytokines, and also leukocyte esterase, when using a cut-off value > 2, could be useful in clinical practice to discriminate between symptomatic and asymptomatic urinary tract infections in the elderly. A combination of IL-6 and leukocyte esterase could be even more useful. This needs to be evaluated in prospective studies on the diagnosis and treatment of urinary tract infections in an elderly population.

Mechanisms of renal damage owing to infection

Urinary tract infection (UTI) is a common bacterial illness in children. It is known to be associated with an increased risk of permanent renal cell damage and scarring which may lead to generation of pathological conditions such as hypertension, pre-eclampsia during pregnancy, renal insufficiency, and end-stage kidney disease. The pathophysiology of renal scarring is still obscure, which makes the prevention of renal damage difficult. During acute infection, there are numerous factors that may contribute to tissue damage. Inflammatory responses are activated by host defense mechanisms as well as by specific bacterial virulence factors. Understanding of these complex mechanisms would be helpful to better identify children at high risk of developing renal scarring following UTI.

Asymptomatic bacteriuria in elderly humans is associated with increased levels of circulating TNF receptors and elevated numbers of neutrophils

Low-grade inflammatory activity is strongly associated with age-associated diseases such as atherosclerosis, dementia, type-2 diabetes, sarcopenia, and osteoporosis and predicts mortality risk in elderly populations. The aim of the current study was to investigate if asymptomatic bacteriuria in elderly humans was associated with inflammation. Midstream clean-catch urine culture was collected from consecutive, elderly patients at admission to a department of internal medicine due to functional disability. Forty patients (age 70-91 years) were selected and included in the current study; 20 subjects had positive urine culture and 20 sex- and age-matched subjects had negative urine culture. Inclusion criteria were temperature below 37.8 degrees C, no clinical signs of infection and no current antibiotic treatment. Patients with asymptomatic bacteriuria had significantly increased levels of circulating tumor necrosis factor receptors (sTNFR-I) and a higher number of neutrophils in the blood compared to the group without bacteriuria. Thus, the present study provides some support for the hypothesis that asymptomatic urinary infections are associated with low-grade immune activity in frail, elderly humans.

Urinary cytokines: clinically useful markers of chronic renal disease progression?

Many factors that drive glomerular and tubulointerstitial fibrogenesis have been identified. These include hemodynamic factors, chemokines, inflammatory mediators, cytokines, and lipids. These strides in knowledge are important in identifying those patients at increased risk of progressive renal disease as well as in developing targets for therapeutic interventions. Identifying 'progressors' is crucial since the distribution of the slope of the glomerular filtration rate of patients with chronic kidney disease is not normal. Some patients appear to progress very rapidly, such as those with diabetes, whereas other patients fail to progress at all. Developing strategies targeted at identifying the fast from the slow progressors is therefore of paramount importance if we are to deploy resources rationally in the management of patients with chronic kidney disease. The use of urinary cytokine markers as predictors of progression of renal disease is reviewed in this paper.

Urinary tract infections in long-term-care facilities

Urinary tract infection (UTI) is the most common bacterial infection occurring in residents of long-term-care facilities. It is a frequent reason for antimicrobial administration, but antimicrobial use for treating UTIs is often inappropriate. Achieving optimal management of UTI in this population is problematic because of the very high prevalence of bacteriuria, evidence that the treatment of asymptomatic bacteriuria is not beneficial, and the clinical and microbiological imprecision in diagnosing symptomatic UTI. This position paper has been developed, using available evidence, to assist facilities and healthcare professionals in managing this common problem.

Increased urinary levels of adrenomedullin in patients with cystitis

In this study, we examined urinary levels of adrenomedullin (AM) in 18 healthy volunteers and 18 patients with cystitis. We also compared urinary levels of AM in 11 patients with cystitis before and after antibiotic treatment. Urinary AM concentrations were measured by a radioimmunoassay specific for human AM. Urinary AM levels in patients with cystitis were significantly elevated compared with those of healthy volunteers and correlated positively with the number of urine leukocytes. By antibiotic treatment, urinary AM levels significantly decreased as compared with before the treatment. By RNA blot analysis of AM transcript, we detected significant levels of AM mRNA in canine urinary bladder and ureter. Intravenous administration of lipopolysaccharide elevated the AM mRNA level in the urinary bladder. These data suggest that infection and inflammation stimulate AM production in the urinary tract, which results in increased urinary AM levels in patients with cystitis. Based on these results, it is deduced that AM participates in the pathophysiology of cystitis, and its urinary level could be used as an index of the degree of cystitis.

Asymptomatic bacteriuria and inflammatory response to urinary tract infection of elderly ambulatory women in nursing homes

BACKGROUND

Bacteriuria > or = 10(5) CFU/ml is evidence of urinary tract infection in the absence of associated signs or symptoms. The presence of pyuria with asymptomatic bacteriuria established the response of elderly women against microorganisms capable of causing invasiveness or tissue injury of the urinary tract.

METHODS

The association between bacteriuria and pyuria was determined in 178 elderly, ambulatory women without symptoms of urinary tract infection in seven nursing homes. Urine culture results were subsequently analyzed in conjunction with absolute leukocyte count in urine. In this cross-sectional study, asymptomatic bacteriuria in elderly women was classified with and without pyuria.

RESULTS

The prevalence of asymptomatic bacteriuria was found in 44 (24.7%) elderly women. The presence of pyuria had a sensitivity of 63.6% for bacteriuria and a specificity of 91%. The positive predictive value for the presence of pyuria predicting those with bacteriuria was 70%, and the negative predictive value for the absence of pyuria predicting those without bacteriuria was 88.4%. Escherichia coli was the most common organism isolated in 81.8% of the women.

CONCLUSIONS

Bacteriuria > or 10(5) CFU/ml associated with pyuria was detected in 77% of elderly women with asymptomatic urinary tract infections. Bacteriuria of < 10(5) CFU/ml with pyuria proves less sensitive as an indicator of urinary tract infection. Elderly women with pyuria but without bacteriuria should be studied for other causes of urinary tract inflammation.

Urinary antibody level and survival in bacteriuric institutionalized older subjects

OBJECTIVE

In a previous study, elevated urine antibody levels in institutionalized subjects with asymptomatic bacteriuria were associated with decreased survival. This study was undertaken to confirm the previous observation in a prospective study in a larger cohort and to explore selected other variables that may be associated with survival.

DESIGN

A prospective, 24-month, observational cohort study.

SETTING

Three large nursing homes in Winnipeg, Manitoba.

PARTICIPANTS

Permanent residents were identified by initial screening urine cultures and subjects with bacteriuria were enrolled. The median age of subjects was 76 years, 51% were women, and the median duration of residence before enrollment was 26 months. Subjects were highly functionally impaired.

MEASUREMENTS

Monthly urine specimens were collected for culture, leukocyte count, and urine antibody. Serum specimens for antibody to uropathogens and IL6 were obtained at enrollment and every 6 months. Anthroporphometric tests of nutritional status and functional and mental status were also measured every 6 months. Residents were stratified as having elevated or not elevated urine antibody, based on the initial urine specimen. The mean urine antibody for all of each subject's specimens was also calculated, and subjects were stratified as low, intermediate, or elevated urine antibody. Outcomes measured included mortality, infection and antibiotic use, and functional, mental, and nutritional decline.

RESULTS

Ninety-eight bacteriuric subjects were enrolled in the study; 34 (35%) had elevated urine antibody and 64 (65%) had not elevated urine antibody. The two groups did not differ in demographic features, co-morbidities, functional status, medication use, or infecting organisms. Survival was significantly (P < .001) poorer in the group with elevated urine antibody. At 24 months, 35% of subjects with an elevated urine antibody were alive compared with 75% with a low urine antibody level. This survival difference was consistent when the two groups were stratified by sex, institution, and presence of a chronic indwelling catheter. Subjects with elevated urine antibody had no evidence for accelerated functional or nutritional decline during the study period compared with the group with low urine antibody. These subjects did, however, have an increased incidence of episodes of symptomatic urinary infection and infections at non-urinary sites.

CONCLUSIONS

Older, bacteriuric, institutionalized subjects with elevated urine antibody had decreased survival rates compared with subjects with lower urine antibody levels. There is no clinical evidence to support accelerated decline caused by chronic infection to explain this observation. Urine antibody may be a marker for immune dysregulation, which precedes death in older impaired subjects.

Asymptomatic bacteriuria in the elderly

Asymptomatic bacteriuria is frequent in elderly, populations. The major contributing factors are selected physiologic aging changes and comorbid illnesses, which occur with increased frequency in these populations. There is little short-term or long-term adverse outcomes attributable to this high prevalence and incidence of asymptomatic bacteriuria and no evidence for an impact on survival. A number of important questions relating to this problem have yet to be resolved. First, further studies in the noninstitutionalized population are needed to characterize the incidence of asymptomatic infection and its relationship to symptomatic infection. In the institutionalized population, studies to refine the clinical diagnosis of symptomatic urinary infection occurring in a population with such a high prevalence of asymptomatic bacteriuria are needed. In addition, further assessment of the impact of the reservoir of asymptomatic bacteriuria in elderly institutionalized subjects as a contributor to the problem of antimicrobial resistance in the institutionalized population should be a priority.

Management of complicated urinary tract infection in older patients

Urinary tract infection (UTI) in older persons is a common medical problem that is seen in both the ambulatory and institutional settings. It affects older women and men with a gender prevalence ratio of 2:1, respectively. UTI in older persons can be a complex problem in terms of the approach to diagnosis, treatment, and prevention. In this report the discussion will begin with the unique aspects of UTI in older persons, particularly as they relate to UTI in the younger, general population. The remaining discussion will then focus on three complicated clinical circumstances and conditions of UTI in the geriatric population: non-catheter recurrent UTI, asymptomatic bacteriuria, and catheter-related bacteriuria and UTI.

Bacteriuria and urinary infections in the elderly

Aging is associated with a decreased physiological functioning, reflecting the body's progressive inability to maintain homeostasis as age increases. The physiologic dysfunctions experienced in response to the aging process increase the individual's susceptibility to infection. Many elderly subjects are hospitalized for the care and treatment of functional disabilities; thus, an increased exposure to possible uropathogens (many with antimicrobial resistance) often results in infection. Additionally, indwelling catheters and other attending procedures may provide a microenvironment conducive to infection. In catheterized patients, the drainage bag often is infected with polymicrobes, which enhances the transference of antimicrobial genetic information. Postmenopause reflects a decrease in circulating estrogen, and a relational decrease in lactobacilli colonization with a lower vaginal pH. Consequently, vaginal colonization with possible uropathogenic and gastrointestinal bacteria increases, which partially may account for the generally higher incidence of bacteriuria in elderly women as opposed to elderly men. Urinary infections in the elderly more commonly are asymptomatic. Treatment for asymptomatic bacteriuria is not justified and will often present opportunities for the infecting organism to acquire antimicrobial resistance. Only symptomatic bacteriuria presenting adverse conditions in the host should be treated. Antimicrobial selection for the treatment of complicating symptomatic urinary infections in elderly subjects is complicated by the many physiological and environmental conditions associated with older age patients. Unfortunately, data confirming the efficacy and safety of antimicrobial agents for the treatment of symptomatic infections in the elderly presently are insufficient.

Interleukin-1 alpha and interleukin-1 receptor antagonist in the urine of children with acute pyelonephritis and relation to renal scarring

Urinary concentrations of interleukin-1 alpha (IL-1 alpha) and interleukin-1 receptor antagonist (IL-lra) standardized to urinary creatinine concentrations were studied. The median standardized IL-1 alpha creatinine quotient in children with first-time acute pyelonephritis was 3.6 pg/mumol, but was nondetectable in children with recurrent pyelonephritis, children with non-renal febrile conditions and children convalescent after acute pyelonephritis (p < 0.05-0.01). IL-lra levels were also significantly higher in children with acute first-time pyelonephritis (median of 239 pg/mumol) compared to these three groups of children (p < 0.01-0.001). The highest urinary IL-lra levels, however, were found in the healthy controls (median value 1.019; p < 0.001). Both cytokines were higher among children younger than one year compared to older children. The acute IL-1 alpha creatinine quotients were lowest in children with uptake defects on 99mTC-dimercaptosuccinic acid (DMSA) scintigraphy both during the acute infection (reflecting the acute inflammation) (p < 0.001) and 1 year after the acute infection (reflecting permanent kidney scarring) (p < 0.001). In conclusion, persisting high urinary levels of IL-1 alpha were associated with less renal inflammation and scarring.

Interleukin-1 increases vacuolar-type H+-ATPase activity in murine peritoneal macrophages

Maintenance of cytoplasmic pH (pHi) within a narrow physiological range is crucial to normal cellular function. This is of particular relevance to phagocytic cells within the acidic inflammatory microenvironment where the pHi tends to be acid loaded. We have previously reported that a vacuolar-type H(+)-ATPase (V-ATPase) situated in the plasma membrane of macrophages and poised to extrude protons from the cytoplasmic to the extracellular space is an important pHi regulatory mechanism within the inflammatory milieu. Since this microenvironment is frequently characterized by the influx of cells known to release inflammatory cytokines, we performed studies to examine the effect of one such mediator molecule, interleukin-1 (IL-1), on pHi regulation in peritoneal macrophages. IL-1 caused a time- and dose-dependent increase in macrophage pHi recovery from an acute acid load. This effect was specific to IL-1 and was due to enhanced plasmalemmal V-ATPase activity. The increased V-ATPase activity by IL-1 occurred following a lag period of several hours and required de novo protein and mRNA synthesis. However, Northern blot analysis revealed that IL-1 did not exert its effect via alterations in the levels of mRNA transcripts for the A or B subunits of the V-ATPase complex. Finally, stimulation of both cAMP-dependent protein kinase and protein kinase C was required for the stimulatory effect of IL-1 on V-ATPase activity. Thus, cytokines present within the inflammatory milieu are able to modulate pHi regulatory mechanisms. These data may represent a novel mechanism whereby cytokines may improve cellular function at inflammatory sites.

Interleukin-6 and interstitial cystitis

We analyzed the presence of the cytokine interleukin-6 in urine samples from interstitial cystitis patients. Interleukin-6 was significantly elevated in patients with interstitial cystitis (169.29 +/- 90.81 pg./ml. versus 34.8 +/- 6.35 pg./ml. in controls). Representative urine samples were analyzed with specific antibody to interleukin-6 and greater than 80% of the biological activity was neutralized. These cytokine measurements were then compared with clinical parameters and interleukin-6 levels correlated positively with the pain scores. Studies on the potential cellular origin of interleukin-6 showed increased levels in spontaneously voided urine but not in ureteral urine, which was collected during cystoscopy, suggesting that interleukin-6 is the product of activated cells in the bladder. This finding is supported by in situ hybridization analyses, which showed that interleukin-6 messenger ribonucleic acid expressing cells are located in the interstitium and epithelial layer, and within blood vessels. The implications of these findings for interstitial cystitis pathogenesis are discussed.