Targeting Asymptomatic Bacteriuria in Antimicrobial Stewardship: the Role of the Microbiology Laboratory

Current and emerging strategies to curb antibiotic-resistant urinary tract infections

Rising rates of antibiotic resistance in uropathogenic bacteria compromise patient outcomes and prolong hospital stays. Consequently, new strategies are needed to prevent and control the spread of antibiotic resistance in uropathogenic bacteria. Over the past two decades, sizeable clinical efforts and research advances have changed urinary tract infection (UTI) treatment and prevention strategies to conserve antibiotic use. The emergence of antimicrobial stewardship, policies from national societies, and the development of new antimicrobials have shaped modern UTI practices. Future UTI management practices could be driven by the evolution of antimicrobial stewardship, improved and readily available diagnostics, and an improved understanding of how the microbiome affects UTI. Forthcoming UTI treatment and prevention strategies could employ novel bactericidal compounds, combinations of new and classic antimicrobials that enhance bacterial killing, medications that prevent bacterial attachment to uroepithelial cells, repurposing drugs, and vaccines to curtail the rising rates of antibiotic resistance in uropathogenic bacteria and improve outcomes in people with UTI.

A quasi-experimental study of a bundled diagnostic stewardship intervention for ventilator-associated pneumonia

OBJECTIVES

Diagnostic error in the use of respiratory cultures for ventilator-associated pneumonia (VAP) fuels misdiagnosis and antibiotic overuse within intensive care units. In this prospective quasi-experimental study (NCT05176353), we aimed to evaluate the safety, feasibility, and efficacy of a novel VAP-specific bundled diagnostic stewardship intervention (VAP-DSI) to mitigate VAP over-diagnosis/overtreatment.

METHODS

We developed and implemented a VAP-DSI using an interruptive clinical decision support tool and modifications to clinical laboratory workflows. Interventions included gatekeeping access to respiratory culture ordering, preferential use of non-bronchoscopic bronchoalveolar lavage for culture collection, and suppression of culture results for samples with minimal alveolar neutrophilia. Rates of adverse safety outcomes, positive respiratory cultures, and antimicrobial utilization were compared between mechanically ventilated patients (MVPs) in the 1-year post-intervention study cohort (2022-2023) and 5-year pre-intervention MVP controls (2017-2022).

RESULTS

VAP-DSI implementation did not associate with increases in adverse safety outcomes but did associate with a 20% rate reduction in positive respiratory cultures per 1000 MVP days (pre-intervention rate 127 [95% CI: 122-131], post-intervention rate 102 [95% CI: 92-112], p < 0.01). Significant reductions in broad-spectrum antibiotic days of therapy per 1000 MVP days were noted after VAP-DSI implementation (pre-intervention rate 1199 [95% CI: 1177-1205], post-intervention rate 1149 [95% CI: 1116-1184], p 0.03).

DISCUSSION

Implementation of a VAP-DSI was safe and associated with significant reductions in rates of positive respiratory cultures and broad-spectrum antimicrobial use. This innovative trial of a VAP-DSI represents a novel avenue for intensive care unit antimicrobial stewardship. Multicentre trials of VAP-DSIs are warranted.

Urinary Tract Infections: The Current Scenario and Future Prospects

Urinary tract infections (UTIs) are among the most common bacterial infections worldwide, occurring in both community and healthcare settings. Although the clinical symptoms of UTIs are heterogeneous and range from uncomplicated (uUTIs) to complicated (cUTIs), most UTIs are usually treated empirically. Bacteria are the main causative agents of these infections, although more rarely, other microorganisms, such as fungi and some viruses, have been reported to be responsible for UTIs. Uropathogenic Escherichia coli (UPEC) is the most common causative agent for both uUTIs and cUTIs, followed by other pathogenic microorganisms, such as Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis, and Staphylococcus spp. In addition, the incidence of UTIs caused by multidrug resistance (MDR) is increasing, resulting in a significant increase in the spread of antibiotic resistance and the economic burden of these infections. Here, we discuss the various factors associated with UTIs, including the mechanisms of pathogenicity related to the bacteria that cause UTIs and the emergence of increasing resistance in UTI pathogens.

A Retrospective, Observational Study of Catheter-Associated Urinary Tract Infection Events Post-Implementation of a Novel Urinary Catheter System with Active Drain Line Clearance and Automated Intra-Abdominal Pressure Monitoring

Objective: A quality improvement study to assess catheter-associated urinary tract infection (CAUTI) rate post-implementation of a bladder catheter with integrated active drain line urine clearance and automated intra-abdominal pressure monitoring in a burn intensive care unit (ICU). DESIGN: Eight-year retrospective before and after study (2015−2022). Setting: A single American Burn Association-verified Burn Center with 14 inpatient beds. Patients: Patients meeting criteria for admission to a Burn Center. Methods: Retrospective cohort study following the implementation of a novel urine output monitoring system with integrated drain line and urine clearance. Data from a 48-month (from January 2015−December 2018) historical control (period 1) were compared to data from a 28-month (from January 2020 to April 2022) post-implementation period (period 2). Pre- and post-implementation CAUTI event incidences were compared. Patients were transferred from outside hospitals with gravity bladder. A distinction in the chart between catheter types was impossible. Charts were reviewed to characterize patients with CAUTI events. Results: A total of 42 CAUTIs in 2243 patients were identified using the National Health and Safety Network (NHSN) definition during the analyzed period. There were 40 CAUTI events in period 1 and two CAUTIs in period 2. The incidence of CAUTI events pre-implementation was 0.030 (mean of 10 CAUTI events per year) compared to 0.002 (mean of 1 CAUTI event per year) post-implementation of an automatic drain line clearing UO monitoring system showing a significant reduction in CAUTI events (p < 0.01, risk ratio novel vs. gravity bladder catheter 0.071, 95% confidence interval: 0.017−0.294). Conclusions: CAUTIs were reduced in the period following the implementation of a novel urinary catheter system with an integrated active drain line and urine clearance in burn patients.

Antimicrobial Stewardship at Transitions of Care to Outpatient Settings: Synopsis and Strategies

Inappropriate antibiotic use and associated consequences, including pathogen resistance and Clostridioides difficile infection, continue to serve as significant threats in the United States, with increasing incidence in the community setting. While much attention has been granted towards antimicrobial stewardship in acute care settings, the transition to the outpatient setting represents a significant yet overlooked area to target optimized antimicrobial utilization. In this article, we highlight notable areas for improved practices and present an interventional approach to stewardship tactics with a framework of disease, drug, dose, and duration. In doing so, we review current evidence regarding stewardship strategies at transitional settings, including diagnostic guidance, technological clinical support, and behavioral and educational approaches for both providers and patients.

Effect of asymptomatic bacteriuria on readmissions and rate of urosepsis after ureterorenoscopy for urolithiasis

Objective:

This study aims to assess whether the rate of readmissions after ureterorenoscopy (URS) is dependent on results of urine microscopy, culture and sensitivity (MC&S) or nitrite dipstick test performed before the procedure.

Patients and Methods:

All patients attending for ureteroscopy for stone disease over 12 months were included and had urine dipstick performed immediately prior to the surgery with mid-stream urine (MSU) sample sent for culture. Asymptomatic bacteriuria (ABU) was not treated before ureteroscopy. All included patients received standard antibiotic prophylaxis. Readmissions within 30 days of the procedure were evaluated.

Results:

A total 120 ureteroscopies were included, of which 20% had ABU. Eight patients (6.67%) were readmitted due to all procedure-related complications; among them, five (4.17%) were readmitted with urinary tract infection (UTI). Readmission rates with UTIs were similar for patients with sterile urine and those who had untreated ABU. Of those patients who were readmitted with UTI, all had a negative nitrite result on preoperative urine dipstick specimens. Most patients (54.17%) who had ABU also had a negative urinary nitrite test.

Conclusions:

Screening and routine treatment of ABU before ureteroscopy for urolithiasis may be unnecessary provided patients have standard antibiotic prophylaxis. Moreover, urine nitrite testing before ureteroscopy may not be a useful screening test for ABU before ureteroscopy.

Level of evidence:

2

Whole-Person, Urobiome-Centric Therapy for Uncomplicated Urinary Tract Infection

A healthy urinary tract contains a variety of microbes resulting in a diverse urobiome. Urobiome dysbiosis, defined as an imbalance in the microbial composition in the microenvironments along the urinary tract, is found in women with uncomplicated urinary tract infection (UTI). Historically, antibiotics have been used to address UTI. An alternative approach to uncomplicated UTI is warranted as the current paradigm fails to take urobiome dysbiosis into account and contributes to the communal problem of resistance. A whole-person, multi-modal approach that addresses vaginal and urinary tract dysbiosis may be more effective in reducing recurrent UTI. In this review, we discuss strategies that include reducing pathogenic bacteria while supporting commensal urogenital bacteria, encouraging diuresis, maintaining optimal pH levels, and reducing inflammation. Strategies for future research are suggested.

Urinary Tract Infections in Kidney Transplant Recipients-Is There a Need for Antibiotic Stewardship?

(1) Background: Urinary tract infections (UTI) are the most common infections after kidney transplantation. Given the risk of urosepsis and the potential threat to the graft, the threshold for treating UTI and asymptomatic bacteriuria with broad spectrum antibiotics is low. Historically fluoroquinolones were prescription favorites for patients that underwent kidney transplantation (KT). After the recent recommendation to avoid them in these patients, however, alternative treatment strategies need to be investigated (2) Methods: We retrospectively analyzed the charts of 207 consecutive adult kidney transplantations that were performed at the department of General, Visceral and Transplantation Surgery of the University Hospital of Tuebingen between January 2015 and August 2020. All charts were screened for the diagnosis and treatment of asymptomatic bacteriuria (ASB) and urinary tract infections (UTI) and the patients' clinical characteristics and outcomes were evaluated. (3) Results: Of the 207 patients, 68 patients suffered from urinary tract infections. Patients who developed UTI had worse graft function at discharge (p = 0.024) and at the 12 months follow-up (p < 0.001). The most commonly prescribed antibiotics were Ciprofloxacin and Piperacillin/Tazobactam. To both, bacterial resistance was more common in the study cohort than in the control group. (4) Conclusions: Urinary tract infections appear to be linked to worse graft functions. Thus, prevention and treatment should be accompanied by antibiotic stewardship teams.

Recurrent Urinary Tract Infections and Asymptomatic Bacteriuria in Adults

Purpose of review

Our goal was to summarize recent evidence regarding recurrent urinary tract infections and asymptomatic bacteriuria in different adult populations.

Recent findings

Several research groups are focused on the description of resident bacterial flora in the bladder and urinary dysbiosis in the microbiome era. Even the definitions might change in light of these discoveries. However, the role of urinary microbiome and bacterial interference has still to be determined.

Summary

Systematic treatment of asymptomatic bacteriuria is not recommended and even classic indications such as asymptomatic bacteriuria in pregnant women are controversial. In fact, its treatment is associated with a higher probability of symptomatic UTI and a higher prevalence of antibiotic-resistant bacteria. Improving the diagnosis of asymptomatic bacteriuria and optimizing the management of recurrent urinary tract infections, especially through non-antibiotics measures, are needed in order to minimise antimicrobial resistance.

Antibiotic use and presumptive pathogens in the Veterans Affairs Healthcare System

BACKGROUND

Empirical antibiotic use is common in the hospital. Here, we characterize patterns of antibiotic use, infectious diagnoses, and microbiological lab results among hospitalized patients and aim to quantify the proportion of antibiotic use that is potentially attributable to specific bacterial pathogens.

METHODS

We conducted an observational study using electronic health records from acute care facilities in the United States Veterans Affairs Healthcare System. From October 2017 to September 2018, 482,381 hospitalizations for 332,657 unique patients that met all criteria were included. At least one antibiotic was administered at 202,037 (41.9%) of included hospital stays. We measured frequency of antibiotic use, microbiological specimen collection, and bacterial isolation by diagnosis category and antibiotic group. A tiered system based on specimen collection sites and diagnoses was used to attribute antibiotic use to presumptive causative organisms.

RESULTS

Specimens were collected at 130,012 (64.4%) hospitalizations with any antibiotic use, and at least one bacterial organism was isolated at 35.1% of these stays. Frequency of bacterial isolation varied widely by diagnosis category and antibiotic group. Under increasingly lenient criteria, 10.2% to 31.4% of 974,733 antibiotic days-of-therapy could be linked to a potential bacterial pathogen.

CONCLUSIONS

Overall, the vast majority of antibiotic use could be linked to either an infectious diagnosis or microbiological specimen. Nearly half of antibiotic use occurred when there was a specimen collected but no bacterial organism identified, underscoring the need for rapid and improved diagnostics to optimize antibiotic use.

Rising prevalence of multidrug-resistant uropathogenic bacteria from urinary tract infections in pregnant women

Objectives

This study aimed to determine the prevalence of urinary tract infections (UTI) in pregnant women and characterise the uropathogenic bacterial strains associated with symptomatic and asymptomatic bacteriuria in Lahore, Pakistan.

Methods

Between December 2018 and June 2019, we analysed the uropathogenic bacterial strains from midstream urine samples in 80 pregnant women. The age of the pregnant women ranged from 19 to 45 years, and they resided in urban and rural areas. We also recorded socioeconomic factors in this cohort. The isolated strains were phenotypically identified and evaluated for multiple drug resistance (MDR) patterns against recommended antimicrobial drugs.

Results

Of the 80 pregnant women, 65 had UTI, reflecting an 81% prevalence of UTI in women during pregnancy. The majority of participants aged 24–35 years, were multipara, and were in their third trimester. Results showed that 67 uropathogenic bacterial strains belonged to Escherichia (31%), Klebsiella (23%), Pseudomonas (16%), Streptococcus (4%), Enterococcus (4%), Staphylococcus (4%), and Proteus (3%) genera, as identified using biochemical characterisation. The highest overall resistance of Escherichia was seen against amoxicillin, pipemidic acid, and ampicillin; for Klebsiella against pipemidic acid, ampicillin, and cefotaxime; and for Pseudomonas against ciprofloxacin and cefotaxime. The three strains with the highest MDR were identified using 16S rRNA as Pseudomonas aeruginosa strain UA17, Escherichia coli strain UA32, and Klebsiella pneumoniae strain UA47.

Conclusion

In this study, the MDR uropathogenic strains showed the highest resistance pattern. The alarming signs of MDR uropathogenic infections are infrequently addressed and thus, urgent attention to this matter is essential.