Risk factors for bacteremia in urinary tract infections attended in the emergency department

Bacteremia From a Presumed Urinary Source in Hospitalized Adults With Asymptomatic Bacteriuria

Importance

Guidelines recommend withholding antibiotics in asymptomatic bacteriuria (ASB), including among patients with altered mental status (AMS) and no systemic signs of infection. However, ASB treatment remains common.

Objectives

To determine prevalence and factors associated with bacteremia from a presumed urinary source in inpatients with ASB with or without AMS and estimate antibiotics avoided if a 2% risk of bacteremia were used as a threshold to prompt empiric antibiotic treatment of ASB.

Design, Setting, and Participants

This cohort study assessed patients hospitalized to nonintensive care with ASB (no immune compromise or concomitant infections) in 68 Michigan hospitals from July 1, 2017, to June 30, 2022. Data were analyzed from August 2022 to January 2023.

Main Outcomes and Measures

The primary outcome was prevalence of bacteremia from a presumed urinary source (ie, positive blood culture with matching organisms within 3 days of urine culture). To determine factors associated with bacteremia, we used multivariable logistic regression models. We estimated each patient's risk of bacteremia and determined what percentage of patients empirically treated with antibiotics had less than 2% estimated risk of bacteremia.

Results

Of 11 590 hospitalized patients with ASB (median [IQR] age, 78.2 [67.7-86.6] years; 8595 female patients [74.2%]; 2235 African American or Black patients [19.3%], 184 Hispanic patients [1.6%], and 8897 White patients [76.8%]), 8364 (72.2%) received antimicrobial treatment for UTI, and 161 (1.4%) had bacteremia from a presumed urinary source. Only 17 of 2126 patients with AMS but no systemic signs of infection (0.7%) developed bacteremia. On multivariable analysis, male sex (adjusted odds ratio [aOR], 1.45; 95% CI, 1.02-2.05), hypotension (aOR, 1.86; 95% CI, 1.18-2.93), 2 or more systemic inflammatory response criteria (aOR, 1.72; 95% CI, 1.21-2.46), urinary retention (aOR, 1.87; 95% CI, 1.18-2.96), fatigue (aOR, 1.53; 95% CI, 1.08-2.17), log of serum leukocytosis (aOR, 3.38; 95% CI, 2.48-4.61), and pyuria (aOR, 3.31; 95% CI, 2.10-5.21) were associated with bacteremia. No single factor was associated with more than 2% risk of bacteremia. If 2% or higher risk of bacteremia were used as a cutoff for empiric antibiotics, antibiotic exposure would have been avoided in 78.4% (6323 of 8064) of empirically treated patients with low risk of bacteremia.

Conclusions and Relevance

In patients with ASB, bacteremia from a presumed urinary source was rare, occurring in less than 1% of patients with AMS. A personalized, risk-based approach to empiric therapy could decrease unnecessary ASB treatment.

Evaluation of the antibacterial activity of Weissella confusa K3 cell-free supernatant against extended-spectrum βeta lactamase (ESBL) producing uropathogenic Escherichia coli U60

Different strategies have been approved for controlling extended-spectrum βeta lactamase (ESBL) producing uropathogenic bacteria. The antibacterial activity of Lactic acid bacteria (LAB) is an effective strategy due to its probiotic characteristics and beneficial effects on human health. The antibiotic susceptibility test, disk diffusion method, and double disc synergy test indicated that five enteric uropathogenic isolates were ESBL producers during the present study. They recorded diameters of inhibition zones as ≤ 18, ≤ 8, ≤ 19, and ≤ 8 mm against cefotaxime (CTX), ceftazidime (CAZ), aztreonam (ATM), and ceftriaxone (CRO). Genotypically, bla_TEM genes are the most common, with (100 %) occurrence in all the five enteric tested uropathogens, followed by bla_SHV and bla_CTX genes (60 %). In addition, out of 10 LAB isolates from dairy products, the CFS of isolate no. K3 had high antibacterial activity against the tested ESBLs, especially no. U60, with a MIC of 600 µl. Additionally, the MIC and sub-MIC of K3 CFS inhibited the production of antibiotic-resistant bla _TEM genes of U60. Analyzing the 16S rRNA sequence confirmed that the most potent ESBL-producing bacteria (U60) and LAB (K3) isolates were identified as Escherichia coli U60.1 and Weissella confuse K3 with accession numbers MW173246 and MW173299.1, respectively, in GenBank.

Evaluation of a carbapenem antimicrobial stewardship program and clinical outcomes in a Japanese hospital

INTRODUCTION

Microorganisms can evolve and become resistant to antimicrobials, and this is known as antimicrobial resistance (AMR). Inappropriate use of antibiotics contributes to AMR, and antimicrobial stewardship programs have been developed to mitigate AMR. The Appropriate Use of Carbapenems Program was implemented in March 2019 in a university hospital and its effect was evaluated.

METHODS

We conducted a prospective audit and feedback on carbapenems at the time of prescription daily. Additionally, we compared a monthly survey of the total days of therapy (DOTs) per 1000 patient-days for carbapenems, piperacillin/tazobactam, and fluoroquinolones. The susceptibility of Pseudomonas aeruginosa to meropenem, piperacillin/tazobactam, and levofloxacin was tested before (January 2018 to February 2019) and after (March 2019 to December 2020) the intervention.

RESULTS

The monthly median DOTs of carbapenem usage decreased after the intervention; carbapenem use immediately declined during the intervention period. The monthly median DOTs of piperacillin/tazobactam and fluoroquinolones also decreased and continued to decline significantly after the intervention. Susceptibility of P. aeruginosa to meropenem, piperacillin/tazobactam, and levofloxacin did not change significantly during the study.

CONCLUSION

The implementation of the Appropriate Use of Carbapenems Program was effective in reducing the use of broad-spectrum antibiotics and maintaining the antibiotic susceptibility of P. aeruginosa.

Evolution of the Antimicrobial resistance of Bacteria causing Urinary Tract Infections

BACKGROUND

The bacteria, Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae), are the main reasons for urinary tract infections (UTIs). This research aimed to investigate the isolation of etiologic agents from patients with UTI; it also investigates the antibiotic resistance activities and incidence of ESBL genes between different clinical separates of uropathogenic E. coli, determining their association with ESBL genes.

METHODS

The study enrolled 1000 positive growth isolates. The predominant pathogen associated with urinary tract infection, Gram-negative, were the main isolates from UTI patients, including E. coli, K. pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus aureus and Enterococcus faecalis.

RESULTS

Among suspicious cases of urinary tract infection, we showed that 15.2% of the patients had UTI, and female patients in the childbearing age group were more affected. 644 E. coli (64.4%) and 322 (32.2%) K. pneumoniae were more isolated. Among 936 (93.6%) ESBL producing bacteria, 614 (61.4 %) E. coli showedhigh resistance to the antibiotics, Cefotaxime (85.7 %), Cefepime (85.7 %), Ciprofloxacin (83.1 %) and Kanamycin (77.9 %). Most ESBL-producing K. pneumoniae were multidrug-resistant (MDR). Nitrofurantoin, gentamycin, and imipenem were the most effective antibiotics for ESBL-producing E. coli isolates.

CONCLUSION

This study shows that the high rates of MDR Escherichia coli infection in our hospital were frequentative reasons for UTI. Nitrofurantoin and aminoglycosides were the most beneficial first-line drugs to be applied in the cases of UTI. It is recommended to conduct regular investigations on the drug resistance of all isolates and formulate helpful antibiotic treatment policies in China. It is important to determine the prevalence of ESBL in urine E. coli and K. pneumoniae isolates because it has a great influence on the selection of suitable antibacterial agents. In short, more than half of ESBL producers have multiple drug resistance (MDR).

Burden of illness in US hospitals due to carbapenem-resistant Gram-negative urinary tract infections in patients with or without bacteraemia

Background

Urinary tract infections (UTIs) are the most common infections caused by Gram-negative bacteria and represent a major healthcare burden. Carbapenem-resistant (CR) strains of Enterobacterales and non-lactose fermenting pathogens further complicate treatment approaches.

Methods

We conducted a retrospective analysis of the US Premier Healthcare Database (2014–2019) in hospitalised adults with a UTI to estimate the healthcare burden of Gram-negative CR UTIs among patients with or without concurrent bacteraemia.

Results

Among the 47,496 patients with UTI analysed, CR infections were present in 2076 (4.4%). Bacteraemia was present in 24.5% of all UTI patients, and 1.7% of these were caused by a CR pathogen. The most frequent CR pathogens were Pseudomonas aeruginosa (49.4%) and Klebsiella pneumoniae (14.2%). Patients with CR infections had a significantly longer hospital length of stay (LOS) (median [range] 8 [5–12] days vs 6 [4–10] days, P < 0.001), were less likely to be discharged home (38.4% vs 51.0%, P < 0.001), had a higher readmission rate (22.6% vs 13.5%, P < 0.001), and had greater LOS-associated charges (mean US$ 91,752 vs US$ 66,011, P < 0.001) than patients with carbapenem-susceptible (CS) infections, respectively. The impact of CR pathogens was greater in patients with bacteraemia (or urosepsis) and these CR urosepsis patients had a significantly higher rate of mortality than those with CS urosepsis (10.5% vs 6.0%, P < 0.001).

Conclusions

Among hospitalised patients with UTIs, the presence of a CR organism and bacteraemia increased the burden of disease, with worse outcomes and higher hospitalisation charges than disease associated with CS pathogens and those without bacteraemia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06229-x.

Does This Patient Need Blood Cultures? A Scoping Review of Indications for Blood Cultures in Adult Nonneutropenic Inpatients

Guidance regarding indications for initial or follow-up blood cultures is limited. We conducted a scoping review of articles published between January 2004 and June 2019 that reported the yield of blood cultures and/or their impact in the clinical management of fever and common infectious syndromes in nonneutropenic adult inpatients. A total of 2893 articles were screened; 50 were included. Based on the reported incidence of bacteremia, syndromes were categorized into low, moderate, and high pretest probability of bacteremia. Routine blood cultures are recommended in syndromes with a high likelihood of bacteremia (eg, endovascular infections) and those with moderate likelihood when cultures from the primary source of infection are unavailable or when prompt initiation of antibiotics is needed prior to obtaining primary source cultures. In syndromes where blood cultures are low-yield, blood cultures can be considered for patients at risk of adverse events if a bacteremia is missed (eg, patient with pacemaker and severe purulent cellulitis). If a patient has adequate source control and risk factors or concern for endovascular infection are not present, most streptococci or Enterobacterales bacteremias do not require routine follow-up blood cultures.

The neutrophil-to-lymphocyte ratio is associated with bacteremia in older adults visiting the emergency department with urinary tract infections

PURPOSE

We evaluated the clinical features of older adults visiting the emergency department (ED) with urinary tract infections (UTIs), and the diagnostic utility of the neutrophil-to-lymphocyte ratio (NLR) in terms of identifying bacteremia.

METHODS

In total, 479 older adults admitted with UTIs via the ED between January 2010 and December 2015 were retrospectively reviewed. We recorded age, sex, comorbidities, body temperature, clinical findings, and initial laboratory results, including the NLR.

RESULTS

A UTI with bacteremia was identified in 186 (38.8%) older adults. Bacteremia was associated with a longer hospital stay (median 10 vs. 8 days, p < 0.001). NLRs and C-reactive protein, blood urea nitrogen and creatinine levels were significantly higher in the bacteremia group than in the non-bacteremia group (p < 0.001, p = 0.016, p = 0.008, and p = 0.011, respectively). The area under the curve for the NLR was 0.624 (95% CI = 0.579-0.668, p < 0.001), and the cutoff was 9.0 (sensitivity 74.2, specificity 49.2%). Independent risk factors for bacteremia were an NLR ≥ 9 and fever ≥ 39 °C (OR 2.43, OR 2.75: p < 0.001, p < 0.001, respectively).

CONCLUSION

Bacteremia was associated with a longer hospital stay in older adults with UTIs, in whom the initial NLR and high fever reliably predicted bacteremia. The NLR may help emergency physicians to predict bacteremia in older adults with UTIs visiting the ED.

Extended-Spectrum β-Lactamase (ESBL) Genotypes among Multidrug-Resistant Uropathogenic Escherichia coli Clinical Isolates from a Teaching Hospital of Nepal

Urinary tract infections (UTI) represent the most common bacterial infections among patients visiting outpatient clinics of healthcare centers in Nepal. However, treatment of such infections is compounded by emergence and spread of multidrug-resistant uropathogens associated with extended-spectrum β-lactamases (ESBLs). In this study, we aimed to investigate the burden of antimicrobial resistance and occurrence of ESBL genes among clinical isolates of uropathogenic Escherichia coli at a tertiary care teaching hospital of Nepal. During the study period, we processed a total of 1,626 urinary tract specimens, isolated significant bacterial pathogens, and investigated their antimicrobial susceptibilities. Escherichia coli (n = 154), the predominant pathogen associated with UTI, was further investigated for the existence of ESBL enzymes by using conventional phenotypic as well as molecular approaches. Among suspected cases of UTI, we found that 15.2% were having UTI and female patients of the reproductive age group were more affected (p < 0.05). Escherichia coli (154, 62.1%) was the key uropathogen, and majority (∼64.9%) of them were multidrug resistant (MDR). Among MDR E. coli isolates, 40.3% were producing extended-spectrum β-lactamases (ESBLs). bla-TEM (83.8%), bla-CTX-M (66.1%), and bla-SHV (4.8%) were common ESBL genotypes. Nitrofurantoin, gentamycin, and imipenem were the most effective antibiotics for ESBL-producing Escherichia coli isolates. It indicates that the high rates of multidrug-resistant Escherichia coli are frequent causes of UTI in our hospital. Nitrofurantoin and aminoglycosides are the most useful first-line drugs to be used in the cases of UTI. We recommend the regular investigation of drug resistance among all isolates and develop a useful antibiotic prescription policy in our country.

A nomogram to predict mortality in patients with severe fever with thrombocytopenia syndrome at the early stage-A multicenter study in China

Background

Severe fever with thrombocytopenia syndrome (SFTS) caused by the SFTS virus is an emerging infectious disease that was first identified in the rural areas of China in 2011. Severe cases often result in death due to multiple organ failure. To date, there are still numerous problems remain unresolved in SFTS, including unclear pathogenesis, lack of specific treatment, and no effective vaccines available.

Aim

To analyze the clinical information of patients with early-stage SFTS and to establish a nomogram for the mortality risk.

Methods

Between April 2011 and December 2018, data on consecutive patients who were diagnosed with SFTS were prospectively collected from five medical centers distributed in central and northeastern China. Multivariable Cox analyses were used to identify the factors independently associated with mortality. A nomogram for mortality was established using those factors.

Results

During the study period, 429 consecutive patients were diagnosed with SFTS at the early stage of the disease (within 7 days of fever), among whom 69 (16.1%) died within 28 days. The multivariable Cox proportional hazard regression analysis showed that low lymphocyte percentage, early-stage encephalopathy, and elevated concentration of serum LDH and BUN were independent risk factors for fatal outcomes. Received-operating characteristic curves for 7-, 14-, and 28-days survival had AUCs of 0.944 (95% CI: 0.920–0.968), 0.924 (95% CI: 0.896–0.953), and 0.924 (95% CI: 0.895–0.952), respectively. Among low-risk patients, 6 patients died (2.2%). Among moderate-risk patients, 25 patients died (24.0%, hazard ratio (HR) = 11.957). Among high-risk patients, the mortality rate was 69.1% (HR = 57.768).

Conclusion

We established a simple and practical clinical scoring system, through which we can identify critically ill patients and provide intensive medical intervention for patients as soon as possible to reduce mortality.

We established a SFTS nomogram scoring system, which is the first nomogram for this disease. According to this nomogram, patients were divided into three levels of mortality risk: low, moderate, and high. This scoring system is helpful to identify critically ill patients, allowing for early intervention and intensive care, which may contribute to reducing the mortality of SFTS.

Evaluation of blood culture epidemiology and efficiency in a large European teaching hospital

Background

Blood cultures remain the gold standard for detecting bacteremia despite their limitations. The current practice of blood culture collection is still inefficient with low yields. Limited focus has been given to the association between timing of specimen collection at different time points during admission and their yield.

Methods

We carried out a retrospective observational study by analyzing all 3,890 sets of cultures collected from the 1,962 admitted patients over the seven-month period of this study. We compared the blood culture yield between the early group (≤24 hours after admission) and the late group (> 24 hours of admission). We also investigated the effect of prehospital oral antibiotics and pre-analytical time on the first cultures in the emergency department. Epidemiology and efficiency of blood cultures were studied for each medical specialty.

Results

In total, 3,349(86.1%) blood cultures were negative and 541(13.9%) were positive for one or more microorganisms. After correcting for contamination, the overall yield was 290 (7.5%). The early group (n = 1,490) yielded significantly more true-positive cultures (10.1% versus 5.8%, P<0.001) than the late group (n = 2,400). The emergency department had a significantly higher yield than general wards, 11.2% versus 5.7% (p<0.001). Prehospital oral antibiotic use and pre-analytical time did not affect the yield of first cultures at the emergency department (p = 0.735 and 0.816 respectively). The number of tests needed to obtain one true-positive culture varied between departments, ranging from 7 to 45.

Conclusion

This study showed that blood cultures are inefficient in detecting bacteremia. Cultures collected during 24 hours after admission yielded more positive results than those collected later. Significant variations in blood culture epidemiology and efficiency per specialty suggest that guidelines should be reevaluated. Future studies should aim at improving blood culture yield, implementing educational programs to reduce contamination and cost-effective application of modern molecular diagnostic technologies.

Nonspecific Symptoms Lack Diagnostic Accuracy for Infection in Older Patients in the Emergency Department

OBJECTIVES

To determine if nonspecific symptoms and fever affect the posttest probability of acute bacterial infection in older patients in the emergency department (ED).

DESIGN

Preplanned, secondary analysis of a prospective observational study.

SETTING

Tertiary care, academic ED.

PARTICIPANTS

A total of 424 patients in the ED, 65 years or older, including all chief complaints.

MEASUREMENTS

We identified presence of altered mental status, malaise/lethargy, and fever, as reported by the patient, as documented in the chart, or both. Bacterial infection was adjudicated by agreement among two or more of three expert reviewers. Odds ratios were calculated using univariable logistic regression. Positive and negative likelihood ratios (PLR and NLR, respectively) were used to determine each symptom's effect on posttest probability of infection.

RESULTS

Of 424 subjects, 77 (18%) had bacterial infection. Accounting for different reporting methods, presence of altered mental status (PLR range, 1.40-2.53) or malaise/lethargy (PLR range, 1.25-1.34) only slightly increased posttest probability of infection. Their absence did not assist with ruling out infection (NLR, greater than 0.50 for both). Fever of 38°C or higher either before or during the ED visit had moderate to large increases in probability of infection (PLR, 5.15-18.10), with initial fever in the ED perfectly predictive, but absence of fever did not rule out infection (NLR, 0.79-0.92). Results were similar when analyzing lower respiratory, gastrointestinal, and urinary tract infections (UTIs) individually. Of older adults diagnosed as having UTIs, 47% did not complain of UTI symptoms.

CONCLUSIONS

The presence of either altered mental status or malaise/lethargy does not substantially increase the probability of bacterial infection in older adults in the ED and should not be used alone to indicate infection in this population. Fever of 38°C or higher is associated with increased probability of infection. J Am Geriatr Soc 67:484-492, 2019.