The Role of Asymptomatic Bacteriuria in Young Women With Recurrent Urinary Tract Infections: To Treat or Not to Treat?

[New aspects on diagnostics and therapy of uncomplicated cystitis]

BACKGROUND

Acute uncomplicated cystitis in women is one of the most frequently diagnosed bacterial infections. A clinically symptomatic urinary tract infection must be differentiated from asymptomatic bacteriuria, which is not considered an infection but more a colonization which as a rule should not be treated. Acute cystitis can also be caused by a low number of uropathogenic bacteria, especially Escherichia coli, which is often overlooked during routine bacteriological diagnostics.

ANTIBIOTIC THERAPY

According to the guidelines the old oral antibiotics (e.g. fosfomycin tromethamine, nitrofurantoin and pivmecillinam) should be prescribed for antimicrobial therapy which are still effective against Escherichia coli in over 90% of cases.

ALTERNATIVE THERAPY

With new therapeutic concepts the elimination of bacteria is no longer the main aim but treatment of the inflammatory (over) reaction of the host. To establish the significance of these therapeutic options as compared to the standard antibiotic therapy, the results of the ongoing and planned phase 3 studies need to be awaited. Thus, reliable clinical measurement parameters for diagnostics and outcome are needed. The acute cystitis symptom score (ACSS) has now also been developed and validated in the German language. Because of its high reliability, validity and predictive value it can be used not only in daily practice but also for clinical studies for the diagnosis of acute uncomplicated cystitis in women.

Impact of host age and parity on susceptibility to severe urinary tract infection in a murine model

The epidemiology and bacteriology of urinary tract infection (UTI) varies across the human lifespan, but the reasons for these differences are poorly understood. Using established monomicrobial and polymicrobial murine UTI models caused by uropathogenic Escherichia coli (UPEC) and/or Group B Streptococcus (GBS), we demonstrate age and parity as inter-related factors contributing to UTI susceptibility. Young nulliparous animals exhibited 10–100-fold higher bacterial titers compared to older animals. In contrast, multiparity was associated with more severe acute cystitis in older animals compared to age-matched nulliparous controls, particularly in the context of polymicrobial infection where UPEC titers were ∼1000-fold higher in the multiparous compared to the nulliparous host. Multiparity was also associated with significantly increased risk of chronic high titer UPEC cystitis and ascending pyelonephritis. Further evidence is provided that the increased UPEC load in multiparous animals required TLR4-signaling. Together, these data strongly suggest that the experience of childbearing fundamentally and permanently changes the urinary tract and its response to pathogens in a manner that increases susceptibility to severe UTI. Moreover, this murine model provides a system for dissecting these and other lifespan-associated risk factors contributing to severe UTI in at-risk groups.

Antimicrobial treatment of asymptomatic bacteriuria in noncatheterized adults: a systematic review

Asymptomatic bacteriuria (ASB) is a common clinical finding characterized by the presence of bacteria in the urine of an individual without signs or symptoms suggestive of urinary tract infection. Despite available guidelines on the diagnosis and management of ASB, it is often managed inappropriately. We performed a systematic review of clinical trials evaluating antimicrobial therapy for ASB, identified translational barriers to evidence-based practice, and we offer strategies to optimize antimicrobial use for ASB. We conducted a systematic search of the PubMed, International Pharmaceutical Abstracts, Cumulative Index to Nursing and Allied Health databases, and the Cochrane Library. Randomized controlled trials, cohort trials, case-control studies, and meta-analyses published in the English language were included in this review if they addressed treatment of ASB with at least one antimicrobial agent in nonpregnant adults. Articles were excluded if they evaluated patients with indwelling urinary catheters or were not clinical trials. Of the 304 articles identified from the search, 287 were excluded; thus 17 articles met the inclusion criteria. Although treatment of ASB with antimicrobial therapy may improve short-term microbiologic outcomes, the clinical significance is diminished because the effect is not sustained, there is no measurable improvement in morbidity or mortality, and some data indicate that therapy is deleterious. Several translational barriers that preclude adoption of evidence-based practice are identified. Treatment guidelines may not achieve their desired effect and underscore the need for additional methods to translate clinical trial data into practice. Clinical pharmacists are a core member of the antimicrobial stewardship team and in an important position to participate in initiatives that promote appropriate antimicrobial use. We suggest a multifaceted approach consisting of education and frequent routine prospective audits with feedback coupled with appropriate process and outcome measures.

Development and validation of a nomogram predicting recurrence risk in women with symptomatic urinary tract infection

OBJECTIVES

To develop and externally validate a novel nomogram predicting recurrence risk probability at 12 months in women after an episode of urinary tract infection.

METHODS

The study included 768 women from Santa Maria Annunziata Hospital, Florence, Italy, affected by urinary tract infections from January 2005 to December 2009. Another 373 women with the same criteria enrolled at Santa Chiara Hospital, Trento, Italy, from January 2010 to June 2012 were used to externally validate and calibrate the nomogram. Univariate and multivariate Cox regression models tested the relationship between urinary tract infection recurrence risk, and patient clinical and laboratory characteristics. The nomogram was evaluated by calculating concordance probabilities, as well as testing calibration of predicted urinary tract infection recurrence with observed urinary tract infections. Nomogram variables included: number of partners, bowel function, type of pathogens isolated (Gram-positive/negative), hormonal status, number of previous urinary tract infection recurrences and previous treatment of asymptomatic bacteriuria.

RESULTS

Of the original development data, 261 out of 768 women presented at least one episode of recurrence of urinary tract infection (33.9%). The nomogram had a concordance index of 0.85. The nomogram predictions were well calibrated. This model showed high discrimination accuracy and favorable calibration characteristics. In the validation group (373 women), the overall c-index was 0.83 (P = 0.003, 95% confidence interval 0.51-0.99), whereas the area under the receiver operating characteristic curve was 0.85 (95% confidence interval 0.79-0.91).

CONCLUSIONS

The present nomogram accurately predicts the recurrence risk of urinary tract infection at 12 months, and can assist in identifying women at high risk of symptomatic recurrence that can be suitable candidates for a prophylactic strategy.

Epidemiology and clinical outcomes of patients with carbapenem-resistant Klebsiella pneumoniae bacteriuria

Carbapenem-resistant Klebsiella pneumoniae (CRKP) bacteriuria is a frequently encountered clinical condition, but its clinical impact is unknown. We conducted a retrospective cohort study to define the epidemiology and outcomes for patients with CRKP bacteriuria. Patients with positive urine cultures for CRKP were classified as having asymptomatic bacteriuria (ASB) or symptomatic urinary tract infection (UTI). Among 105 patients with CRKP bacteriuria, 80% (84/105 patients) and 20% (21/105 patients) had ASB and UTI, respectively. Older age (P = 0.002) and higher Charlson's comorbidity index scores (P = 0.001) were associated with ASB. The median duration of hospitalization prior to CRKP bacteriuria was significantly longer for patients with ASB versus UTI (8.5 versus 2 days; P = 0.05). In multivariate analysis, male sex (odds ratio [OR], 4.69 [95% confidence interval (CI), 1.44 to 15.26]; P = 0.01), solid-organ transplantation (OR, 4.50 [95% CI, 1.39 to 14.52]; P = 0.01), and neurogenic bladder (OR, 18.62 [95% CI, 1.75 to 197.52]; P = 0.01) were independently associated with UTI. Ten percent (8/84) of the patients with ASB received antimicrobial therapy. The treatment success rate for patients with UTIs was 90% (19/21 patients), including all patients who received doxycycline (n = 9). The overall 30-day mortality rate was 6% (6/105 patients); the deaths were unrelated to CRKP infections. Secondary CRKP infections, including UTIs, were notably absent among patients with ASB who were followed for 90 days. In conclusion, identification of CRKP in the urine was most commonly associated with ASB and did not lead to subsequent infections or death among asymptomatic patients. Factors associated with UTIs included male sex, solid-organ transplantation, and neurogenic bladder. Doxycycline may be an effective therapy for CRKP UTIs.

Obesity and iron deficiency anemia as risk factors for asymptomatic bacteriuria

BACKGROUND

Few studies examined the risk factors of asymptomatic bacteriuria, showing contradictory results. Our study aimed to examine the association between different clinical and laboratory parameters and asymptomatic bacteriuria in internal medicine patients.

MATERIALS AND METHODS

330 consecutive hospitalized subjects, asymptomatic for urinary tract infections (UTIs), underwent to microscopic examination of urine specimens. 100 subjects were positive for microscopic bacteriuria and were recruited into the study. At the quantitative urine culture 31 subjects of study population were positive while 69 subjects were negative for bacteriuria.

RESULTS

The analysis of clinical characteristics showed that the two groups of subjects (positive and negative urine culture for bacteriuria) were significant different (p<0.05) about obesity (76.7% vs 42% respectively), metabolic syndrome (80.6% vs 44,9%), cholelithiasis (35.5% vs 13,2%) and iron deficiency anemia (80.6% vs 53,6%). The univariate analysis showed that only obesity, cholelithiasis and iron deficiency anemia were positively associated with positive urine culture for bacteriuria (Odds Ratios [OR]=3.79, p=0.0003; OR=2,65, p=0.0091; OR=2.63, p=0.0097; respectively). However, the multivariate analysis by logistic regression showed that only obesity and iron deficiency anemia, independently associated with positive urine culture for bacteriuria (OR=3.9695, p=0.0075; OR=3.1569, p=0.03420 respectively).

CONCLUSIONS

This study shows that obesity and iron deficiency anemia are independent risk factors for asymptomatic bacteriuria.

Reducing antimicrobial therapy for asymptomatic bacteriuria among noncatheterized inpatients: a proof-of-concept study

This proof-of-concept study demonstrates that no longer routinely reporting urine culture results from noncatheterized medical and surgical inpatients can greatly reduce unnecessary antimicrobial therapy for asymptomatic bacteriuria without significant additional laboratory workload. Larger studies are needed to confirm the generalizability, safety, and sustainability of this model of care.

Urinary tract infection syndromes: occurrence, recurrence, bacteriology, risk factors, and disease burden

Urinary tract infection (UTI) is one of the most common bacterial infections, accounting for 0.9% of all ambulatory visits in the United States. This review defines the major UTI syndromes, their occurrence and recurrence, bacteriology, risk factors, and disease burden.

Approach to a positive urine culture in a patient without urinary symptoms

Asymptomatic bacteriuria (ASB) is a condition in which bacteria are present in a noncontaminated urine sample collected from a patient without signs or symptoms related to the urinary tract. ASB must be distinguished from symptomatic urinary tract infection (UTI) by the absence of signs and symptoms compatible with UTI or by clinical determination that a nonurinary cause accounts for the patient's symptoms. The overall purpose of this review is to promote an awareness of ASB as a distinct condition from UTI and to empower clinicians to withhold antibiotics in situations in which antimicrobial treatment of bacteriuria is not indicated.

From infection to immunotherapy: host immune responses to bacteria at the bladder mucosa

The pathogenesis of urinary tract infection and mechanisms of the protective effect of Bacillus Calmette-Guerin (BCG) therapy for bladder cancer highlight the importance of studying the bladder as a unique mucosal surface. Innate responses to bacteria are reviewed, and although our collective knowledge remains incomplete, we discuss how adaptive immunity may be generated following bacterial challenge in the bladder microenvironment. Interestingly, the widely held belief that the bladder is sterile has been challenged recently, indicating the need for further study of the impact of commensal microorganisms on the immune response to uropathogen infection or intentional instillation of BCG. This review addresses the aspects of bladder biology that have been well explored and defines what still must be discovered about the immunobiology of this understudied organ.

Virulence factors of uropathogenic Escherichia coli of urinary tract infections and asymptomatic bacteriuria in children

BACKGROUND/PURPOSE

The clinical aspects of virulence genes of uropathogenic Escherichia coli (UPEC) are not fully understood. This study compared the presence of virulence genes in UPEC isolated from urinary tract infections (UTIs) and asymptomatic bacteriuria (ABU) in children.

METHODS

The study included children with UTI (n = 15) or ABU (n = 49) treated at Chung-Ang University Yongsan Hospital between 2010 and 2011. The strains were acquired from each urine sample collected, and 18 major virulence genes were detected by polymerase chain reaction. Antimicrobial susceptibility of all UPEC isolates was determined.

RESULTS

Sixty-four E. coli strains were isolated from the urine samples. The most commonly identified virulence gene in both groups was fimH (100.0% in the UTI group and 95.9% in the ABU group). The UTI isolates showed a higher prevalence of papEF and fyuA, and a lower prevalence of feoB than ABU isolates (p < 0.01 for all). The profile of virulence gene, fimH(+)kpsMTII(+)feoB(+) also showed a significant difference between the two groups (p < 0.01). Isolates from ABU were more resistant to most antimicrobials tested. The presence of papEF, feoB, and fyuA also correlated with the antimicrobial susceptibility of UPEC.

CONCLUSION

The virulence gene repertoire was different in the UPEC of UTI and ABU. The papEF, feoB, and fyuA genes showed meaningful differences between the two groups and may have an important role in the pathogenesis of overt UTI.

Prevention of recurrent urinary tract infections in women

Around 40-50% of women experience at least one urinary tract infection (UTI) during their lifetime and 20-30% of these have a recurrence within 3-4 months of the initial infection.¹ Recurrent UTI (usually defined as three episodes in the last 12 months or two episodes in the last 6 months) can have a considerable impact on a woman's quality of life. Each episode of acute UTI in young women is typically associated with about 6 days of symptoms, 2.4 days of restricted activities and 0.4 days of bed rest.¹ Antibacterial prophylaxis is effective in preventing recurrent episodes, but at the expense of unwanted effects and a risk of promoting bacterial resistance. Here we assess the efficacy of different antibacterial regimens and non-antibacterial alternatives (cranberry, probiotics, oestrogens, immunostimulation, hyaluronic acid and chondroitin, acupuncture and herbs) in the prevention of recurrent uncomplicated UTIs in women.

Patient characteristics but not virulence factors discriminate between asymptomatic and symptomatic E. coli bacteriuria in the hospital

Background

Escherichia coli is a common cause of asymptomatic and symptomatic bacteriuria in hospitalized patients. Asymptomatic bacteriuria (ASB) is frequently treated with antibiotics without a clear indication. Our goal was to determine patient and pathogen factors suggestive of ASB.

Methods

We conducted a 12-month prospective cohort study of adult inpatients with E. coli bacteriuria seen at a tertiary care hospital in St. Louis, Missouri, USA. Urine cultures were taken at the discretion of treating physicians. Bacterial isolates were tested for 14 putative virulence genes using high-throughput dot-blot hybridization.

Results

The median age of the 287 study patients was 65 (19–101) years; 78% were female. Seventy percent had community-acquired bacteriuria. One-hundred ten (38.3%) patients had ASB and 177 (61.7%) had symptomatic urinary tract infection (sUTI). Asymptomatic patients were more likely than symptomatic patients to have congestive heart failure (p = 0.03), a history of myocardial infarction (p = 0.01), chronic pulmonary disease (p = 0.045), peripheral vascular disease (p = 0.04), and dementia (p = 0.03). Patients with sUTI were more likely to be neutropenic at the time of bacteriuria (p = 0.046). Chronic pulmonary disease [OR 2.1 (95% CI 1.04, 4.1)] and dementia [OR 2.4 (95% CI 1.02, 5.8)] were independent predictors for asymptomatic bacteriuria. Absence of pyuria was not predictive of ASB. None of the individual virulence genes tested were associated with ASB nor was the total number of genes.

Conclusions

Asymptomatic E. coli bacteriuria in hospitalized patients was frequent and more common in patients with dementia and chronic pulmonary disease. Bacterial virulence factors could not discriminate symptomatic from asymptomatic bacteriurias. Asymptomatic E. coli bacteriuria cannot be predicted by virulence screening.

Alternative approaches to conventional treatment of acute uncomplicated urinary tract infection in women

The increasing resistance of uropathogens to antibiotics and recognition of the generally self-limiting nature of uncomplicated urinary tract infection (UTI) suggest that it is time to reconsider empirical treatment of UTI using antibiotics. Identifying new and effective strategies to prevent recurrences and alternative treatment strategies are a high priority. We review the recent literature regarding the effects of functional food products, probiotics, vaccines, and alternative treatments on treating and preventing UTI.