Blood culture useful only in selected patients with urinary tract infections – a literature review

Development and validation of artificial intelligence models to predict urinary tract infections and secondary bloodstream infections in adult patients

BACKGROUND

Traditional culture methods are time-consuming, making it difficult to utilize the results in the early stage of urinary tract infection (UTI) management, and automated urinalyses alone show insufficient performance for diagnosing UTIs. Several models have been proposed to predict urine culture positivity based on urinalysis. However, most of them have not been externally validated or consisted solely of urinalysis data obtained using one specific commercial analyzer.

METHODS

A total of 259,187 patients were enrolled to develop artificial intelligence (AI) models. AI models were developed and validated for the diagnosis of UTI and urinary tract related-bloodstream infection (UT-BSI). The predictive performance of conventional urinalysis and AI algorithms were assessed by the areas under the receiver operating characteristic curve (AUROC). We also visualized feature importance rankings as Shapley additive explanation bar plots.

RESULTS

In the two cohorts, the positive rates of urine culture tests were 25.2% and 30.4%, and the proportions of cases classified as UT-BSI were 1.8% and 1.6%. As a result of predicting UTI from the automated urinalysis, the AUROC were 0.745 (0.743-0.746) and 0.740 (0.737-0.743), and most AI algorithms presented excellent discriminant performance (AUROC > 0.9). In the external validation dataset, the XGBoost model achieved the best values in predicting both UTI (AUROC 0.967 [0.966-0.968]) and UT-BSI (AUROC 0.955 [0.951-0.959]). A reduced model using ten parameters was also derived.

CONCLUSIONS

We found that AI models can improve the early prediction of urine culture positivity and UT-BSI by combining automated urinalysis with other clinical information. Clinical utilization of the model can reduce the risk of delayed antimicrobial therapy in patients with nonspecific symptoms of UTI and classify patients with UT-BSI who require further treatment and close monitoring.

Effect of Prior Antibiotic Treatment on Blood Culture in an Outpatient Department of General Internal Medicine: A Retrospective Case-Control Analysis

Purpose

The effect of antibiotics administered before blood cultures performed in general internal medicine outpatient settings is not well known.

Patients and Methods

We conducted a retrospective case-control study including adult patients who underwent blood cultures in the general internal medicine outpatient department of a Japanese university hospital between 2016 and 2022. Patients with positive blood cultures were included as cases and matched patients with negative blood cultures were included as controls. Univariable and multivariable logistic regression analyses were performed.

Results

A total of 200 patients and 200 controls were included. Antibiotics were administered prior to blood culture in 20% of patients (79/400). Oral antibiotics were prescribed to 69.6% of the prior antibiotics (55/79). Prior antibiotic use was significantly lower among patients with positive than negative blood cultures (13.5% vs 26.0%, p = 0.002) and was an independent predictive factor in univariable (odds ratio, 0.44; 95% confidence interval, 0.26-0.73; p = 0.002) and multivariable (adjusted odds ratio, 0.31; 95% confidence interval, 0.15-0.63; p = 0.002) logistic regression models for positive blood culture. The area under the receiver operating characteristic (AUROC) curve of the multivariable model for predicting positive blood cultures was 0.86.

Conclusion

There was a negative correlation between prior antibiotic use and positive blood cultures in the general internal medicine outpatient department. Therefore, physicians should interpret the negative results of blood cultures performed after the administration of antibiotics with care.

[Infectious emergencies in urology]

OBJECTIVE

To report the nature, diagnosis and therapeutic strategy of infectious emergencies in urology.

MATERIAL AND METHODS

Bibliographic research from Pubmed, Embase, and Google scholar in July 2021. A synthesis of the guidelines of national infectious diseases societies.

RESULTS

Urosepsis and complicated urinary tract infection have a standardized definition. Diagnosis and therapeutic strategy are presented for upper tract urinary infection, male urinary infection, healthcare associated urinary infection, symptomatic canduria and urinary infections of the elderly. Appropriate antibiotherapy should be tailored to the degree of severity, bacterial ecosystem, patient characteristics et localization of the infection.

CONCLUSION

Urinary infections can be critical and require immediate care. Knowledge of the guidelines and of appropriate diagnosis and therapeutics strategy improve care which should be rapidly applied, and collegial.

Seven Versus 14 Days of Antibiotic Therapy for Uncomplicated Gram-negative Bacteremia: A Noninferiority Randomized Controlled Trial

BACKGROUND

Gram-negative bacteremia is a major cause of morbidity and mortality in hospitalized patients. Data to guide the duration of antibiotic therapy are limited.

METHODS

This was a randomized, multicenter, open-label, noninferiority trial. Inpatients with gram-negative bacteremia, who were afebrile and hemodynamically stable for at least 48 hours, were randomized to receive 7 days (intervention) or 14 days (control) of covering antibiotic therapy. Patients with uncontrolled focus of infection were excluded. The primary outcome at 90 days was a composite of all-cause mortality; relapse, suppurative, or distant complications; and readmission or extended hospitalization (>14 days). The noninferiority margin was set at 10%.

RESULTS

We included 604 patients (306 intervention, 298 control) between January 2013 and August 2017 in 3 centers in Israel and Italy. The source of the infection was urinary in 411 of 604 patients (68%); causative pathogens were mainly Enterobacteriaceae (543/604 [90%]). A 7-day difference in the median duration of covering antibiotics was achieved. The primary outcome occurred in 140 of 306 patients (45.8%) in the 7-day group vs 144 of 298 (48.3%) in the 14-day group (risk difference, -2.6% [95% confidence interval, -10.5% to 5.3%]). No significant differences were observed in all other outcomes and adverse events, except for a shorter time to return to baseline functional status in the short-course therapy arm.

CONCLUSIONS

In patients hospitalized with gram-negative bacteremia achieving clinical stability before day 7, an antibiotic course of 7 days was noninferior to 14 days. Reducing antibiotic treatment for uncomplicated gram-negative bacteremia to 7 days is an important antibiotic stewardship intervention.

CLINICAL TRIALS REGISTRATION

NCT01737320.

Usefulness of next-generation DNA sequencing for the diagnosis of urinary tract infection

Acute urinary tract infection (UTI) is a highly common clinical condition. Although bacterial culture is the gold standard diagnostic test, false negative results may be possible, leading to the pathogen being unidentified. In recent years, bacterial DNA sequencing analysis has garnered much attention, but clinical studies are rare in Japan. In this study, we assessed the usefulness of next-generation DNA sequencing (NGS) analysis for acute UTI patients. We thus performed an observational, retrospective case series study. Urine and blood samples were collected from ten acute UTI patients, of whom four had also been diagnosed with urosepsis. Seven variable regions of bacterial 16S rRNA genes were amplified by PCR and then sequenced by IonPGM. The identified bacterial species were compared with those identified using the culture tests and the clinical parameters were analyzed. As a result, the NGS method effectively identified predominant culture-positive bacteria in urine samples. The urine NGS also detected several culture-negative species, which have been reported to be potentially pathogenic. Out of four urosepsis cases, three were pathogen-positive in blood NGS results, while two were pathogen-negative in blood culture. In one sepsis case, although blood culture was negative for Escherichia coli, this species was detected by blood NGS. For non-sepsis cases, however, blood NGS, as well as blood culture, was less effective in detecting bacterial signals. In conclusion, NGS is potentially useful for identifying pathogenic bacteria in urine from acute UTI patients but is less applicable in patients who do not meet clinical criteria for sepsis.

Clinical impact of perinephric fat stranding detected on computed tomography in patients with acute pyelonephritis: a retrospective observational study

Perinephric fat stranding (PFS) is often detected on computed tomography (CT) in patients with acute pyelonephritis (APN). However, its clinical impact remains unclear. This study aimed to evaluate the clinical impact of PFS detected on CT in patients with APN. This retrospective observational study included patients with APN who underwent CT (median age, 79.5 years). Patients were classified into PFS (patients with PFS observed on CT) and non-PFS (patients without PFS observed on CT) groups, which were further classified into bacteraemia and non-bacteraemia groups. Clinical findings between the groups were compared. Among 194 patients who underwent CT, 111 (57.2%) patients demonstrated PFS. The rate of bacteraemia was significantly higher in the PFS group than in the non-PFS group (55.2 vs. 23.1%, p < 0.001). CT findings other than PFS were not associated with bacteraemia. The median peak body temperature was significantly higher in the PFS group than in the non-PFS group (38.8 vs. 38.5 °C, p < 0.001); however, the duration of fever and in-hospital mortality rates were not significantly different between the groups. Concordance between blood and urine culture results was observed in 75.0% of the patients; the presence of PFS was not different between patients with concordant and discordant results, regardless of the pre-treatment antibiotic used. Our findings suggest that the presence of PFS in patients with APN predicts bacteraemia; thus, clinicians should consider obtaining blood cultures if PFS is found on CT in patients with APN, even if the patients had received antibiotics prior to admission.

A significant percentage of patients with transrectal biopsy-related infections have positive blood cultures but negative urine cultures. A literature review and meta-analysis

BACKGROUND

Infectious complications after transrectal prostate biopsy are rare. Nevertheless, since these are frequent procedures, the burden of infectious complications is high. Considering the increasing antimicrobial resistance, microbiological confirmation is important to guide antimicrobial therapy.

METHODS

We reviewed PubMed for original studies providing concurrent urine and blood culture data in symptomatic patients with transrectal biopsy-related infectious complications. We performed a proportions meta-analysis (with MedCalc) and calculated the pooled yield of urine and blood cultures and the pooled discordance rate between urine and blood cultures.

RESULTS

Our review identified 41 studies, involving 852 patients with infectious complications after transrectal prostate biopsy and sufficient data to calculate discordance. The pooled yield of urine cultures was 64.6% (95% CI: 56.2-72.3%, I² 83%), the pooled yield of blood cultures was 43% (95% CI: 36.5-49.7%, I² 74%) and the pooled discordance rate was 14% (95% CI: 10.6-17.8%, I² 53%). In subgroup analyses the pooled discordance was; 19.6% (95% CI: 11.8-28.9%, I² 31%) in 113 patients presenting within 2 calendar days after the biopsy and 11.2% (95% CI: 4.5-20%, I² 47%) in 143 patients presenting with fever and symptoms of lower urinary tract symptoms. The statistical and methodological heterogeneity of included studies was high.

CONCLUSION

Obtaining blood cultures is reasonable in all patients presenting with systemic symptoms suggestive of infection after a transrectal prostate biopsy. Blood cultures can provide additional microbiological data in about 1 of 7 patients with post-biopsy infectious complications. Prospective studies are needed to validate these results.

Atypical Presentation of IgA Nephropathy Mimicking Acute Pyelonephritis

Background

IgA glomerulonephritis may present with hematuria, flank pain, and fever. This clinical presentation may be easily confused with acute pyelonephritis.

Case Report

We present the case of a 25-year-old female with a typical clinical presentation for acute pyelonephritis (high fever, left flank pain, left costovertebral angle tenderness, hematuria, elevated inflammatory markers, and a hypoenhancing region in the left kidney on contrast-enhanced computed tomography). However, urine and blood cultures were both negative, the serum creatinine was elevated, and the urinalysis revealed significant proteinuria and dysmorphic red blood cells. A kidney biopsy confirmed a diagnosis of IgA nephropathy. She was treated with a combination of lisinopril and methylprednisolone, with good response.

Conclusion

Gross hematuria, especially in the absence of pyuria or bacteriuria, should raise the suspicion for underlying IgA nephropathy, even if the rest of the clinical presentation is typical for a urinary tract infection. The presence of significant proteinuria, red blood cell casts, and dysmorphic red blood cells are useful clues suggesting glomerular disease.