Association of Appropriate Empirical Antimicrobial Therapy With In-Hospital Mortality in Patients With Bloodstream Infections in the US

Impact of an antibiotic stewardship programme in the emergency department of a secondary hospital

INTRODUCTION

Emergency Departments (ED) are usually the first point of contact between patients and hospitals. There is no solid evidence evaluating the activity of antibiotic stewardship programs (ASP) in EDs. We aimed to assess antibiotic prescription appropriateness after the implementation of an ASP in an ED in May 2019 and to determine the risk factors associated with inappropriate antibiotic prescription.

METHODS

A cross-sectional study was conducted with patients admitted to the ED of the University Hospital Fundación Alcorcón, a second-level university hospital in Spain. All patients admitted to the ED in May 2019, March 2021, and between October and November 2022 were included. We analyzed demographic data, epidemiological variables, comorbidities, empirical antibiotic treatment, previous isolations, and treatment duration. A 30-day follow-up was implemented.

RESULTS

A total of 402 patients were included. No significant improvement in antibiotic appropriateness was observed between the first and second periods (50 % vs. 57.3 %; OR = 1.3, 95 % CI: 0.65-2.76, p = 0.424), while antibiotic appropriateness increased between the first and third periods (50 % vs. 71.2 %; OR = 2.47, 95 % CI: 1.28-4.79, p = 0.007). Factors associated with antibiotic inadequacy were having a urinary catheter (33 % vs. 56 %, p = 0.008, OR: 2.62, 95 % CI: 1.29-5.33), a history of infection/colonization by multidrug-resistant microorganisms (32 % vs. 57 %, p = 0.007), and coming from a retirement home or medium-stay hospital (32 % vs. 47 % vs. 53 %, p = 0.015).The overall use of carbapenems was 9 % (n = 36), showing a decrease in consumption between the first and third periods (26.2 % vs. 7 % vs. 7 %, p < 0.01).

Predictors of mortality of enterococcal bacteraemia and the role of source control interventions; a retrospective cohort study

PURPOSE

To identify predictors of mortality among patients with enterococcal bacteraemia.

METHODS

This retrospective study was conducted at the Lausanne University Hospital, Switzerland and included adult patients with enterococcal bacteraemia from 2014 to 2023.

RESULTS

During the study period, 768 enterococcal bacteraemia episodes were included. The predominant species was Enterococcus faecalis (427 episodes; 56%). Sepsis or septic shock were present in 351 (46%) episodes. The overall 30-day mortality rate was 19% (148 episodes). The Cox multivariable regression model showed that age > 60 years (aHR: 1.75, 95% CI: 1.05-2.90), nosocomial infection (1.78, 1.19-2.65), sepsis or septic shock (3.67, 2.48-5.45), and not performing source control interventions within 48 h, in patients on or discussing of transitioning to limitations of care (5.91, 3.13-11.14) were associated with 30-day mortality. Conversely, infectious diseases (ID) consultation within 48 h (0.40, 0.28-0.57), appropriate antimicrobial therapy within 48 h (0.54, 0.34-0.86), and source control interventions performed within 48 h (0.22, 0.14-0.36) or not warranted (0.54; 0.34-0.86) were associated with survival. Among the 737 episodes without limitation of care, the Cox multivariable regression model showed that nosocomial infection (1.78, 1.19-2.67), sepsis or septic shock (3.76, 2.42-5.82), were associated with 30-day mortality. Conversely, ID consultation within 48 h (0.44, 0.30-0.65), appropriate antimicrobial therapy within 48 h (0.51, 0.30-0.86), and source control interventions performed within 48 h (0.25, 0.16-0.40) or not warranted (0.40; 0.26-0.61) were associated with survival.

CONCLUSIONS

Our findings underscore the pivotal role of early management of enterococcal bacteraemia, including ID consultation, appropriate antimicrobial treatment initiation and performance of source control interventions.

Multi-center evaluation of the Selux next-generation phenotyping system for gram-negative direct-from-positive blood culture antimicrobial susceptibility testing

Accurate and rapid antimicrobial susceptibility test (AST) results from positive blood cultures are crucial for patient care and combatting antimicrobial resistance. Although recent advancements in rapid direct-from-positive blood culture (PBC) identification platforms have enabled the provision of species-level identification and some resistance marker information within hours after blood culture positivity, AST results required for clinical decision-making often require 48 h after blood culture positivity. This study evaluated the Selux next-generation phenotyping system, including an automated PBC Separator and the Selux AST system in a multicenter clinical trial for their ability to perform AST directly from PBCs for gram-negative bacilli. The PBC separator produces McFarland equivalent inocula from positive blood cultures within 1 h, facilitating direct processing on the Selux AST system. The study evaluated 162 fresh clinical PBC samples, 307 seeded clinical samples, and 87 seeded challenge samples across 4 sites for each of the 17 antimicrobials included in the panel. The results demonstrate that the Selux system's clinical performance, reproducibility, and analytical performances are consistent when using positive blood cultures held for up to 16 h after positivity on the BACTEC and BacT/ALERT 3D and BacT/ALERT VIRTUO blood culture systems, including all major BACTEC and BacT/ALERT blood culture bottle types. These findings suggest that the PBC Separator with the Selux AST system is a valuable addition to the arsenal of tools available for rapid sepsis diagnosis and management.IMPORTANCETechnologies that consistently and substantially shorten the time between blood bottle positivity, organism identification, and complete AST results are crucial for ensuring that antimicrobial therapy can be tailored. The Selux PBC Separator and the Selux AST system perform rapid AST directly from positive blood culture bottles. This substantially shortens the gap between obtaining a positive blood bottle and organism identification and the availability of a fully actionable AST result.

Incidence, case-fatality rates and risk factors of bloodstream infections caused by Escherichia coli, Klebsiella species and Pseudomonas aeruginosa, England, April 2017 to March 2022

BackgroundEscherichia coli, Klebsiella spp. and Pseudomonas aeruginosa are included in the mandatory surveillance of bloodstream infections (BSI) in England.AimWe aimed to investigate the epidemiology of these BSIs in England April 2017-March 2022.MethodsWe extracted data on E. coli, Klebsiella spp. and P. aeruginosa BSI, categorised BSIs as healthcare-associated (HA) or community-associated (CA) and linked to antimicrobial susceptibility and mortality data. We used multivariable logistic regression models to assess predictors of mortality.ResultsThe incidence rate of E. coli BSI was 71.8 per 100,000 population (95% confidence interval (CI): 71.5-72.1), Klebsiella spp. 19.1 (95% CI: 18.9-19.3) and P. aeruginosa 7.6 (95% CI: 7.5-7.7). Most (65,467/104,957) BSI episodes were CA. Case-fatality rate was 14.8% (95% CI: 14.6-14.9) in E. coli, 20.0% (95% CI: 19.6-20.3) in Klebsiella spp. and 25.8% (95% CI: 25.2-26.4) in P. aeruginosa BSI. Urinary tract infection (UTI) was the most reported primary infection for E. coli (56,961/100,834), Klebsiella spp. (9,098/22,827) and P. aeruginosa (3,204/8,484) BSI. Insertion or manipulation of urinary catheters was reported for 26.4% (16,136/61,043) of E. coli, 41.6% (4,470 /10,734) of Klebsiella spp. and 49.0% (2,127/4,341) of P. aeruginosa BSI. The adjusted odds ratio (OR) of death among hospital-onset HA-BSI compared to CA-BSI was 2.0 (95% CI: 1.9-2.2) for E. coli, 2.1 (95% CI: 2.0-2.3) for Klebsiella spp. and 1.7 (95% CI: 1.5-2.0) for P. aeruginosa.ConclusionsAppropriate management of UTIs and urinary catheterisation is essential for reduction of these BSIs.

Pathogenic bacteria features of central line-associated bloodstream infections in ICU patients: focus on the early predictive value of neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios

Objective

Explore and analyze CLABSI pathogenic bacteria characteristics in ICU patients and the value of PCT, NLR, PLR in early infection prediction.

Methods

926 ICU patients with central venous catheters in Minhang Hospital from January 2021 to December 2023 were enrolled. They were grouped by co-infection status. PCT, NLR and PLR levels were measured, patient data analyzed, pathogenic bacteria characteristics summarized, and their predictive value evaluated via ROC curve.

Results

From January 2021 to December 2023, among the 926 patients with CVC, 73 were diagnosed with CLABSI, with an infection rate of 7.88%. A total of 81 strains of pathogenic bacteria were isolated, including 60.50% (49/81) Gram - positive bacteria, 35.80% (29/81) Gram - negative bacteria, and 3.70% (3/81) fungi. The main Gram - positive bacteria exhibited high resistance to penicillin, erythromycin, clindamycin, and oxacillin, with a resistance rate exceeding 70%, yet were sensitive to vancomycin, linezolid, and tetracycline. The main Gram - negative bacteria had high resistance to piperacillin, piperacillin/tazobactam, Aztreonam, and gentamicin, with a resistance rate over 70%, and were more sensitive to cefoperazone/sulbactam, imipenem, and amikacin. Age, the site of catheterization, the duration of catheterization, and the employment of double - cavity catheters were all factors that exerted an influence on CLABSI among ICU patients (with p < 0.05). The levels of peripheral blood NLR, PLR, and PCT in the infected group were higher than those in the non - infected group (p < 0.05). The areas under the curve (AUCs) of peripheral blood NLR, PLR, and PCT were 0.814, 0.798, and 0.856, respectively, with the largest AUC for PCT. When the cut - off point was 2.75 ng/ml, the Youden index was the largest. The AUCs of the combination of peripheral blood NLR and PLR, NLR and PCT, PLR and PCT, and all three combined were 0.877, 0.903, 0.857, and 0.917.

Conclusion

The early prediction of CLABSI in ICU patients by means of PCT, NLR, and PLR is of remarkable significance. It can provide a precious reference for clinical diagnostic and treatment strategies.

Management practices and mortality predictors among Klebsiella pneumoniae infections across Lebanese hospitals: a multicenter retrospective study

BACKGROUND

Klebsiella pneumoniae is a significant cause of both community-acquired and nosocomial infections, leading to high morbidity and mortality rates. The increasing antimicrobial resistance among K. pneumoniae strains poses a critical challenge to effective treatment. This study aimed to assess the appropriateness of initial antimicrobial therapy, determine the 30-day all-cause mortality rate, and identify predictors of mortality among patients infected with K. pneumoniae in Lebanese hospitals.

METHODS

A multicenter retrospective observational study was conducted across three university hospitals in Beirut, Lebanon. The study included hospitalized adult patients with confirmed K. pneumoniae infections. Kaplan-Meier survival analysis and log-rank tests were used to analyze time-to-mortality. Binary logistic regression was performed to identify predictors of mortality.

RESULTS

Of 2,655 cases screened, 410 patients were enrolled, and 395 cases were included in the final analysis of the 30-day mortality after excluding those lost to follow-up. Nearly one-third of the isolates (36.8%) were extended-spectrum β-lactamase (ESBL)-producing, while 6.8% were carbapenem-resistant K. pneumoniae (CRKP). The most commonly prescribed empirical antibiotics were meropenem (31.7%), amikacin (28.5%), and ceftriaxone (22.2%). Around one-third of the patients (32.9%) received inappropriate initial antimicrobial therapy. The 30-day mortality rate was 14.4%. Main predictors significantly associated with mortality in patients with K. pneumoniae infection were solid cancer (adjusted odds ratio [AOR] = 7.82, P < 0.01), coronary artery disease (AOR = 4.81, P = 0.01), age ≥ 65 years (AOR = 4.22, P = 0.02), type II diabetes mellitus (AOR = 3.96, P = 0.01), receiving inappropriate initial antimicrobial therapy (AOR = 2.96, P = 0.02), infection with CRKP isolates (AOR = 2.53, P = 0.03), and having a higher Charlson comorbidity index (AOR = 1.61, P = 0.001).

CONCLUSIONS

The study highlights the critical need for effective antimicrobial stewardship and tailored infection control protocols to mitigate the high resistance rates and improve patient outcomes in Lebanon. Emphasis should be placed on enhancing the monitoring of local resistance patterns and using these data to guide the selection of appropriate empirical therapy to reduce mortality associated with K. pneumoniae infections.

MultiSeq-AMR: a modular amplicon-sequencing workflow for rapid detection of bloodstream infection and antimicrobial resistance markers

Bloodstream infections (BSIs) represent a significant global health challenge, and traditional diagnostic methods are suboptimal for timely guiding targeted antibiotic therapy. We introduce MultiSeq-AMR, a rapid and modular nanopore amplicon-sequencing workflow to identify bacterial and fungal species and a comprehensive set of antimicrobial resistance (AMR) genes (n=91) from various types of infection sources. We initially benchmarked MultiSeq-AMR using DNA from 16 bacterial and 5 fungal reference strains and accurately identified all species. AMR gene identification exhibited 99.4% categorical agreement (CA: 153/154 prediction) with whole-genome sequencing. Further validation with 33 BACT/ALERT positive samples from suspected BSI cases revealed 100% accuracy for genus and 96.7% for species identification, with 97.4% CA (151/155) for AMR gene prediction. To accelerate microbiological diagnosis, a 6 h culture enrichment step was tested with MultiSeq-AMR using 15 clinically important bacterial species. Of 13 species selected for sequencing, 11 were correctly identified, with 96% CA (59/61 predictions) for AMR gene identification. With only 2 Mbp yield, sequencing identified 93.7% of species and 89.8% AMR genes initially detected with 20-50 Mbp yield/sample. MultiSeq-AMR holds promise for BSI diagnosis, as species/AMR genes could be identified under 5 h of BACT/ALERT positivity and potentially <11 h of sample collection (rapid-enrichment) for a large set of bacterial species. MultiSeq-AMR gene targets can be modified/increased indefinitely to suit user needs. Further research is required to clinically validate MultiSeq-AMR, especially the rapid enrichment method, to assess its utility in a medical setup and in improving patient outcomes in BSI.

Accuracy of classification of urinary Gram-stain findings by a computer-aided diagnosis app compared with microbiology specialists

Introduction. Timely and accurate diagnosis of bacterial infections enables early administration of appropriate antimicrobial treatment and improved outcomes.Hypothesis/Gap Statement. The accuracy of computer-aided diagnosis (CAD) for identifying organisms on urine Gram stains has not been compared with that of microbiology specialists (MS).Aim. To compare the interpretation of urine Gram-stain results by MS and a CAD app designed using artificial intelligence.Methodology. Urine specimens from patients with urinary tract infections were used and collected at two tertiary hospitals between 1 April and 31 December 2022. Using non-inferiority analysis to assess whether CAD was non-inferior to expert interpretation, CAD-predicted microscopic findings of the Gram-stained slide generated from iPhone camera images from two hospitals were compared with those from ten MS. A total of 153 images were taken from each hospital, and CAD interpreted a total of 306. The primary endpoint was the prediction accuracy based on the morphology of the Gram-stained bacteria.Results. The accuracy (95% confidence interval) of MS and CAD predictions was 83.0% (81.6%-84.3%) and 87.9% (83.7%-91.3%), respectively, with a difference of -4.93% (-8.43% to -0.62%) indicating non-inferiority of CAD.Conclusion. CAD was non-inferior to MS predictions for identifying Gram-stained pathogens; therefore, CAD was suggested to have the potential for guiding empirical antibiotic selection in patients with urinary tract infections.

Epidemiology and Resistance Profiles of Bacteria Isolated From Blood Samples in Septic Patients at Emergency Department Admission: A 6-Year Single Centre Retrospective Analysis From Northern Italy

OBJECTIVE

This study aimed to investigate the microbiological and clinical heterogeneity of community-onset bloodstream infections (BSIs) and identify features to support targeted empirical antibiotic therapy in the Emergency Department (ED).

METHODS

Clinical and microbiological data from 992 BSI cases (1,135 isolates) diagnosed within 24 h of ED admission at IRCCS Humanitas Research Hospital, Milan, Italy (January 2015-June 2022), were analysed. Drug resistance was interpreted using EUCAST-2023. Clinical features included age, sex, comorbidities (e.g., cancer, diabetes), infection source, presence of central venous catheters (CVC), ongoing therapies, and sepsis severity. Microbiological data included pathogen identification and antimicrobial susceptibility.

RESULTS

Antibiotic-susceptible Escherichia coli (29.5%) was the most common isolate, including extended-spectrum beta-lactamase (ESBL)-producing strains (11.3%), followed by methicillin-susceptible Staphylococcus aureus (MSSA, 8.4%). BSIs due to E. coli were more frequent in patients >60 years (43.9% vs. 27.3%, P < 0.001) and associated with ESBL production (OR = 2.202, P = 0.031) and urosepsis (OR = 1.688, P = 0.006). Younger patients (≤60 years) had more S. aureus-associated BSIs (22.4% vs. 10.8%, P < 0.001) and methicillin resistance (7.9% vs. 3.6%, P = 0.021). Carbapenem-resistant Enterobacterales were rare (2.1%-2.8%), predominantly involving Klebsiella pneumoniae. Onco-hematological patients had a lower multidrug-resistance prevalence (9.5% vs. 21.1%, P < 0.001).

CONCLUSIONS

Community-onset BSIs demonstrated substantial prevalence of resistant pathogens, including ESBL and MRSA, emphasizing the need for robust surveillance systems. Age is a critical factor in guiding empirical antibiotic therapy in the ED.

Rapid identification of pathogenic bacteria from clinical positive blood cultures via virus-like magnetic bead enrichment and MALDI-TOF MS profiling

Reducing the time required for the detection of bacteria in blood samples is a critical area of investigation in the field of clinical diagnosis. Positive blood culture samples often require a plate culture stage due to the interference of blood cells and proteins, which can result in significant delays before the isolation of single colonies suitable for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. In this study, we developed a non-specific enrichment strategy based on SiO2-encapsulated Fe3O4 nanoparticles combined with MALDI-TOF MS for direct identification of bacteria from aqueous environments or positive blood culture samples. Three distinct types of Fe3O4@SiO2 magnetic nanoparticles (MNPs) with unique surface morphologies were developed: spherical MNPs with smooth surfaces (Fe3O4@SN), mesoporous silica coated MNPs (Fe3O4@MSN), and MNPs exhibiting a viral spiked structure (Fe3O4@VSN). These MNPs exhibited excellent binding affinity towards both Staphylococcus aureus and Klebsiella pneumoniae in PBS and artificial saliva solutions. Furthermore, the strategy of using Fe3O4@VSN, which involves non-specific interactions between bacterial cells and the virus-like surface, resulted in a dramatic reduction in the minimum detectable concentrations of target pathogens by up to 1000-fold compared to conventional methods. Our results demonstrate that the use of Fe3O4@VSN has the potential to significantly reduce the processing time required after blood culture and may be useful for enrichment and identification of microorganisms in complex clinical samples.

Identification of Pathogens in HIV-Infected Patients Using Metagenomic Next-Generation Sequencing (mNGS) as Compared to Conventional Microbiological Tests (CMTs)

Background

The rapid and accurate identification of infectious pathogens in HIV-infected patients remains a challenge. Metagenomic next-generation sequencing (mNGS) is a panpathogen assay for rapid diagnosis of infectious diseases. Here, the diagnostic value of mNGS was evaluated in HIV-infected patients and compared with conventional microbiological tests (CMTs).

Methods

This study was conducted on 216 hIV-infected patients with suspected opportunistic infections. Infectious pathogen detection was done by mNGS and conventional microbiological tests, respectively.

Results

A total of 195 patients (90.2%) were positive for microbial pathogens by mNGS, while 135 patients (62.5%) were positive for microbial pathogens by CMTs. Mixed infection was identified in 92 patients by mNGS, and 41 patients were detected with mixed infection by CMTs. Fungi and virus mixed infection was the most frequent pattern detected by mNGS (32, 14.8%) and CMTs (22, 10.2%). The CD4+ T cell count in patients with mixed pathogens was significantly lower than that in patients infected with a single pathogen. Pathogens were quickly identified by mNGS in 151 patients (69.9%), and appropriate treatments were initiated. In 47 patients antibacterial agents were adjusted based on mNGS results, in 39 patients antifungal agents were changed, and 35 patients had antiviral agents added.

Conclusion

mNGS is a valuable tool and enhances rapid microbiological identification in HIV-infected patients. Combined with CMTs, mNGS may facilitate personalized antimicrobial treatment strategies and increase survival.

Predictive Value of Direct Disk Diffusion Testing from Positive Blood Cultures for Detection of Antimicrobial Nonsusceptibility

Antibiotic resistance poses a significant global threat, particularly in the context of bloodstream infections. Early antimicrobial susceptibility testing plays a crucial role in guiding clinicians to optimize treatment and enhance patient outcomes. Direct disk diffusion testing (dDDT), utilizing positive blood culture broth as an inoculum, provides results one day earlier than the standard method using bacterial colonies. This retrospective study evaluated the ability of dDDT to predict nonsusceptibility to commonly used antibiotics. From January 2021 to December 2023, a total of 1473 blood cultures positive for a single pathogen (Enterobacterales, Pseudomonas aeruginosa, Staphylococcus aureus, β-hemolytic streptococci, or Enterococcus spp.) were examined. The results of dDDT were compared against the standard disk diffusion method as the reference standard. A total of 9754 organism-antibiotic pairs were analyzed. The positive predictive values were more than 98% for clinically significant resistant phenotypes, including ceftriaxone, ceftazidime, cefepime, and meropenem nonsusceptibility in Enterobacterales, ceftazidime and meropenem nonsusceptibility in P. aeruginosa, and cefoxitin resistance in S. aureus. Overall, sensitivities exceeded 98% for the majority of organism-antibiotic pairs, with specificities ranging from 88.4% to 100%. Categorical agreement was high at 97.9%, ranging from 88.8% to 100% across organism groups. The overall rates of major error and very major error were very low, at 0.2% and 0.04%, respectively, and ranged from 0% to 1.5% and 0% to 0.04%, respectively, across organism groups. In conclusion, dDDT is a reliable and expedient method for detecting antibiotic nonsusceptibility, making it a valuable tool for the timely management of bloodstream infections caused by resistant organisms.

Ten-Year Evaluation of Ventilator-Associated Pneumonia (VAP) According to Initial Empiric Treatment: A Retrospective Analysis Using Real-World Data

Background/Objectives: Ventilator-associated pneumonia (VAP) is the main nosocomial infection in intensive care units (ICUs) that causes the highest morbidity and mortality. The aim of our study is to investigate variations in crude ICU mortality among patients with VAP over the past decade. We also wish to identify associated risk factors, evaluate changes in the etiology, and assess the incidence and impact of inappropriate empirical antibiotic treatment (IEAT). Methods: We conducted a retrospective, observational, single-center study over a 10-year period (2014-2024), including critically ill patients who developed VAP. The population was divided into three periods: (P1) from 2014 to 2018 (pre-COVID-19); (P2) from 2019 to 2021 (COVID-19); and (P3) from 2022 to 2024 (post-COVID-19). Binary logistic regression was used to identify which variables were independently associated with ICU mortality. Results: A total of 220 patients were included in the study (P1 = 47, P2 = 96, and P3 = 77 patients). The most prevalent microorganisms identified were P. aeruginosa, Klebsiella spp., and S. aureus. Significant variations in etiology were not observed over the years. The incidence of IEAT was 4.5%, with no observed differences between the study periods. Crude ICU mortality was 33.6%, with higher rates observed in IEAT (40% vs. 33.3%, p = 0.73). In patients with appropriate empiric antibiotic treatment (AEAT), there was a significant decrease in crude mortality over the years from 42.2% in P1 to 22.2% in P3 (p < 0.001). Age (OR = 1.04; 95% CI = 1.01-1.08) and P2 (OR = 2.8; 95% CI = 1.1-7.4) were found to be independently associated with an increased risk of mortality. Conversely, a lower risk of death was associated with mean arterial pressure (OR = 0.94; 95% CI = 0.69-0.99) and the use of syndromic respiratory panel (OR = 0.23; 95% CI = 0.07-0.68). Conclusions: A reduction in crude VAP mortality over the years was observed, with no change in the etiology or rate of IEAT. The implementation of protocols using respiratory syndromic panels could be a measure to implement to reduce VAP mortality.

Microbiological and Clinical Features of Patients with Cellulitis in Tropical Australia: Disease Severity Assessment and Implications for Clinical Management

Australian guidelines for the treatment of cellulitis are informed by data from temperate, metropolitan centers. It is uncertain if these guidelines are equally applicable in tropical Australia, where the population, access to healthcare, and array of potential pathogens are quite different. This retrospective study examined adults admitted to Cairns Hospital in tropical Queensland, Australia, who were treated with intravenous antibiotics for a principal diagnosis of cellulitis in 2019. The study aimed to describe the epidemiological, clinical, and microbiological findings in these cases and the resulting implications for patient management. There were 305 episodes of cellulitis; a potential pathogen was identified in 93/305 (30%), most commonly Staphylococcus aureus (45/93, 48%) or Group A Streptococcus (16/93, 17%). There was one case of Burkholderia pseudomallei. Initial treatment was most commonly with narrow spectrum β-lactam antibiotics with flucloxacillin prescribed in 170/305 (56%) and cefazolin prescribed in 74/305 (26%). Overall, 4/305 (1%) died or were admitted to the intensive care unit (ICU) within 30 days, 123/305 (40%) had an inpatient stay >48 hours, and 63/305 (21%) were readmitted to hospital within 30 days. Every patient who subsequently died or required ICU admission had an elevated early warning score (EWS ≥3) on admission. An EWS ≥3 on admission also predicted an inpatient stay of >48 hours (odds ratio [OR]: 3.2, 95% CI: 1.7-6.0; P <0.001) and 30-day readmission (OR: 2.3, 95% CI: 1.2-4.6; P = 0.01). The etiology of cellulitis in tropical Queensland, Australia, is very similar to that seen in temperate regions, enabling the use of standard management algorithms for patients with cellulitis in the region.

Effect of empiric antibiotics against Pseudomonas aeruginosa on mortality in hospitalized patients: a systematic review and meta-analysis

BACKGROUND

Empiric antibiotics active against Pseudomonas aeruginosa are recommended by professional societies for certain infections and are commonly prescribed for hospitalized patients. The effect of this practice on mortality is uncertain.

METHODS

A systematic literature search was conducted using Embase, Medline, PubMed, Web of Science, Cochrane, Scopus and Google Scholar from earliest entry through 9 October 2023. We included studies of patients hospitalized with P. aeruginosa infections that compared mortality rates depending on whether patients received active empiric antibiotics.

RESULTS

We found 27 studies of 12 522 patients that reported adjusted OR of active empiric antibiotics on mortality. The pooled adjusted OR was 0.40 (95% CI, 0.32-0.50), favouring active empiric antibiotics. In practice, the mortality effect of empiric antibiotics against P. aeruginosa depends on the prevalence of P. aeruginosa and baseline mortality. The estimated absolute mortality benefit was 0.02% (95% CI, 0.02-0.02) for soft tissue infections, 0.12% (95% CI, 0.10-0.13) for urinary tract infections and community-acquired pneumonia, 0.3% (0.25-0.34) for sepsis without shock, 1.1% (95% CI, 0.9-1.4) for septic shock and 2.4% (95% CI, 1.9-2.8) for nosocomial pneumonia.

CONCLUSIONS

The mortality effect for empiric antibiotics against P. aeruginosa depends crucially on the prevalence of P. aeruginosa and baseline mortality by type of infection. For soft tissue infections, urinary tract infections and community-acquired pneumonia, the mortality benefit is low. Meaningful benefit of empiric antibiotics against P. aeruginosa is limited to patients with approximately 30% mortality and 5% prevalence of P. aeruginosa, which is largely limited to patients in intensive care settings.

Seven versus 14 days of antimicrobial therapy for severe multidrug-resistant Gram-negative bacterial infections in intensive care unit patients (OPTIMISE): a randomised, open-label, non-inferiority clinical trial

BACKGROUND

Shorter courses of antimicrobial therapy have been shown to be non-inferior to longer durations for the management of several infections. However, data on critically ill patients with severe infections by multidrug-resistant Gram-negative bacteria (MDR-GNB) are scarce. In the duratiOn of theraPy in severe infecTIons by MultIdrug-reSistant gram-nEgative bacteria (OPTIMISE) trial, we assessed the non-inferiority of 7-day versus 14-day antimicrobial therapy for patients with intensive care unit (ICU)-acquired severe infections by MDR-GNB.

METHODS

This was a randomised multicenter, open-label, parallel controlled, non-inferiority trial. Adult patients with severe infections by MDR-GNB initiated ≥ 48 h of ICU admission were eligible if they were hemodynamically stable and without fever > 48 h on the 7th day of appropriate antimicrobial therapy. Patients were 1:1 randomised to discontinue antimicrobial therapy on the 7th (± 1) day or to continue for a total of 14 (± 1) days. The primary outcome was clinical failure, defined as death or relapse of infection within 28 days of randomisation. An upper edge of the two-tailed 95% confidence interval (CI) of the delta between the clinical failure rate in the 7- and the 14-day lower than 10% in both intention-to-treat (ITT) and per protocol (PP) analyses was set as the non-inferiority criteria.

RESULTS

A total of 106 patients composed the ITT population: 59 and 47 allocated to 7- and 14-day groups, respectively. The PP population included 75 patients: 47 and 28 in the 7- and 14-day groups, respectively. Clinical failure occurred in 42.4% and 44.7% of the ITT population in 7- and 14-day groups, respectively, (risk difference (RD) - 2.3, 95%CI - 21.3 to 16.7), and in 46.8% and 50.0% of the PP population in 7- and 14-day groups, respectively (RD - 3.2, 95%CI - 26.6 to 20.2).  Most infections were of the respiratory tract (73/68.9%) and caused by carbapenem-resistant Enterobacterales (42/39.6%). The study was interrupted before reaching planned sample size due to low recruitment rate.

CONCLUSION

The OPTIMISE trial could not determine the non-inferiority of 7-day compared to 14-day therapy for severe infections caused by MDR-GNB due to early termination related to the low recruitment rate.

TRIAL REGISTRATION

NCT05210387 on January 13, 2022.

Strategies to reduce 28-day mortality in adult patients with bacteremia in the emergency department

BACKGROUND

Bacteremia, a common emergency department presentation, has a high burden of mortality, cost and morbidity. We aimed to identify areas for potential improvement in emergency department bacteremia management.

METHODS

This retrospective cohort study included adults with bacteremia in an emergency department in 2019 and 2022. The primary outcome was 28-day mortality. Descriptive analyses evaluated demographics, comorbidities and clinical characteristics. Univariate and multivariate analyses identified mortality predictors.

RESULTS

Overall, 433 patients were included [217 males (50.1%), mean ± SD age: 74.1 ± 15.2 years]. The 28-day mortality rate was 15.2% (n = 66). In univariate analysis, age ≥ 70 years, arrival by ambulance, arrhythmia, congestive heart failure, recent steroid use, hypotension (< 90/60 mmHg), mechanical ventilation, cardiac arrest, intensive care unit (ICU) admission, intravenous antibiotics, pneumonia as bacteremia source, non-urinary tract infections, no infectious disease consultation, no antibiotic adjustment and no control blood cultures were significantly associated with 28-day mortality (p < 0.05). Malignancy showed a statistical trend (0.05 < p < 0.15). The above-stated sixteen variables, identified in univariate analysis, were assessed via multivariate analysis. Primarily, clinical relevance and, secondarily, statistical significance were used for multivariate model creation to prioritize pertinent variables. Five risk factors, significantly associated with mortality (p < 0.05), were included in the model: ICU admission [adjusted OR (95% CI): 6.03 (3.08-11.81)], pneumonia as bacteremia source [4.94 (2.62-9.32)], age ≥ 70 [3.16 (1.39-7.17)], hypotension [2.12 (1.02-4.40)], and no infectious disease consultation [2.02 (1.08-3.78)]). Surprisingly, initial antibiotic administration within 6 h, inappropriate initial antibiotic regimen and type of bacteria (Gram-negative, Gram-positive) were non-significant (p > 0.05).

CONCLUSIONS

We identified significant mortality predictors among emergency department patients presenting with bacteremia. Referral to an infectious disease physician is the only modifiable strategy to decrease 28-day mortality with long-term effect and should be prioritized.

Clinical Outcomes of Early Phenotype-Desirable Antimicrobial Therapy for Enterobacterales Bacteremia

Importance

Initiating effective therapy early is associated with improved survival among patients hospitalized with gram-negative bloodstream infections; furthermore, providing early phenotype-desirable antimicrobial therapy (PDAT; defined as receipt of a β-lactam antibiotic with the narrowest spectrum of activity to effectively treat the pathogen's phenotype) is crucial for antimicrobial stewardship. However, the timing of targeted therapy among patients hospitalized with gram-negative bloodstream infections is not well understood.

Objective

To compare the clinical outcomes between patients who were hospitalized with Enterobacterales bloodstream infections receiving early vs delayed PDAT.

Design, Setting, and Participants

This retrospective cohort study used a large, geographically diverse, hospital-based US database (PINC AI Healthcare Database). Participants were adult (aged ≥18 years) patients with an inpatient admission between January 1, 2017, and June 30, 2022, with at least 1 blood culture isolate positive for Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, or Proteus mirabilis and receiving PDAT on blood culture collection days 0 to 4.

Exposure

Early vs delayed PDAT, with early PDAT defined as receipt of PDAT on blood culture collection days 0 to 2.

Main Outcomes and Measures

The main outcome was desirability of outcome ranking, in which patients were assigned a mutually exclusive rank 1 through 5. Rank 1 indicated the most desirable outcome (alive with no events), whereas rank 5 indicated the least desirable outcome and included all patients who died within 30 days of blood culture collection.

Results

Among 8193 eligible patients (mean [SD] age, 69.0 [16.4] years; 4758 [58.1%] female; 1200 [14.6%] African American or Black, 729 [8.9%] Hispanic, and 5778 [70.5%] White) from 252 hospitals, 5033 (61.4%) received early PDAT. Patients receiving early PDAT were similar in age (mean [SD], 68.2 [16.9] vs 70.3 [15.6] years) but more likely to have a lower median (IQR) Charlson-Deyo comorbidity score (2 [1-5] vs 3 [1-5]) compared with patients receiving delayed PDAT. After adjusting for comorbidities and severity of illness, patients receiving early PDAT were 20% less likely to be readmitted within 30 days compared with those receiving delayed PDAT (odds ratio, 0.80; 95% CI, 0.69-0.92; P < .001). A higher percentage of patients receiving early PDAT had a desirability of outcome ranking of 1 compared with patients receiving delayed PDAT (56.3% vs 52.2%, P < .001). Those receiving early PDAT had a 52.5% probability (95% CI, 51.3%-53.7%) of a more desirable outcome than those receiving delayed PDAT, a finding that persisted in the adjusted analysis (probability, 52.0%; 95% CI, 50.9%-53.2%).

Conclusions and Relevance

Receiving early PDAT was associated with favorable 30-day clinical outcomes among patients hospitalized with Enterobacterales blood stream infections. Early PDAT may be important not only for antimicrobial stewardship but also for improving patient outcomes.

Impact of inappropriate empirical antibiotic therapy on in-hospital mortality: a retrospective multicentre cohort study of patients with bloodstream infections in Chile, 2018-2022

Introduction

Empirical antibiotic therapy is essential for treating bloodstream infections (BSI), yet there is limited evidence from resource-limited settings. We quantified the association of inappropriate empirical antibiotic therapy (IEAT) with in-hospital mortality and the associated burden on BSI patients in Chile.

Methods

We used a retrospective multicentre cohort study of BSI cases in three Chilean tertiary hospitals (2018-2022) to assess the impact of IEAT on 30-day and overall in-hospital mortality and quantify excess disease and economic burdens associated with IEAT. We determined the appropriateness of pathogen-antimicrobial pairings based on in vitro susceptibilities and pathogen-corresponding antibiotic treatment, allowing a 48-hour window after the initial blood culture. We addressed confounding using propensity scores and inverse probability weights (IPW). We used IPW-weighted logistic competing-risk survival models, including time-varying independent variables after blood tests as controls.

Results

Among 1323 BSI episodes, 432 (33%) received IEAT, with an average time to adequate therapy of 4.6 days. Compared with adequate treatment, IEAT was associated with 30-day and overall mortality risks that were 1.31 and 1.24 times higher, respectively. These risks were further inflated between twofold and fourfold when antibiotic-resistant bacteria (ARB) was included. Competing-risk models showed associations between IEAT and IEAT-ARB combinations with in-hospital mortality. Accounting for time-varying variables yielded similar results. The economic burden of IEAT resulted in an additional cost of ~US$9900 from premature mortality and 0.46 disability-adjusted life-years per patient with BSI.

Conclusion

Approximately one in three patients received IEAT, often associated with ARB. IEAT was linked to increased mortality risk and higher economic costs. Timely appropriate treatment, early pathogen detection and resistance profiling are likely to improve health and financial outcomes at the population level.

Fluoroquinolones tackling antimicrobial resistance: Rational design, mechanistic insights and comparative analysis of norfloxacin vs ciprofloxacin derivatives

Antimicrobial resistance poses a global health concern and develops a need to discover novel antimicrobial agents or targets to tackle this problem. Fluoroquinolone (FN), a DNA gyrase and topoisomerase IV inhibitor, has helped to conquer antimicrobial resistance as it provides flexibility to researchers to rationally modify its structure to increase potency and efficacy. This review provides insights into the rational modification of FNs, the causes of resistance to FNs, and the mechanism of action of FNs. Herein, we have explored the latest advancements in antimicrobial activities of FN analogues and the effect of various substitutions with a focus on utilizing the FN nucleus to search for novel potential antimicrobial candidates. Moreover, this review also provides a comparative analysis of two widely prescribed FNs that are ciprofloxacin and norfloxacin, explaining their rationale for their design, structure-activity relationships (SAR), causes of resistance, and mechanistic studies. These insights will prove advantageous for new researchers by aiding them in designing novel and effective FN-based compounds to combat antimicrobial resistance.

Clinical characteristics and mortality risk factors of premature infants with carbapenem-resistant Klebsiella pneumoniae bloodstream infection

Due to the resistance of carbapenem-resistant Klebsiella pneumoniae (CRKP) to most antibiotics, CRKP treatment is challenging, which results a high mortality rate. CRKP infection poses a significant challenge for infection management and treatment, especially among neonates and premature infants. Therefore, it is important to understand the clinical characteristics of CRKP bloodstream infection (BSI) in premature infants and identify the related risk factors for death. This study aims to explore and analyze the clinical characteristics and risk factors affecting mortality of BSI caused by CRKP in premature infants. A retrospective study was conducted in a Children's Hospital in Henan to analyze clinical data of premature infants with CRKP BSI admitted from January 2015 to December 2022. Univariate and multivariate logistic regression models were utilized to investigate risk factors affecting mortality. Receiver operating characteristic curves were employed to evaluate the predictive value of different indicators on mortality, and differences in area under the curve (AUC) were compared using Stata 17 SE. A total of 96 premature infants with CRKP BSI were enrolled, including 70 patients in the survival group and 26 in the death group. At the onset of infection, 69 (71.9%) patients exhibited persistent tachycardia (heart rate > 180 beats/min), 61 (63.5%) had fever, and 59 (61.4%) experienced apnea episodes. Concurrent meningitis (OR 9.588, 95% CI 1.401-57.613, P = 0.021), concurrent necrotizing enterocolitis (NEC) (OR 7.881, 95% CI 1.672-73.842, P = 0.032), and the maximum vasoactive-inotropic score (VIS) value within 48 h of onset (OR 1.467, 95% CI 1.021-1.782, P = 0.001) were identified as independent risk factors for mortality. The univariate analysis showed that ceftazidime-avibactam (CAZ/AVI) treatment and appropriate early antimicrobial treatment were significantly associated with survival (P < 0.05). The combined predictive AUC for mortality in premature infants with CRKP BSI using the maximum VIS value ≥ 52.5 points within 48 h of onset, concurrent NEC, and purulent meningitis was 0.931 (95% CI 0.856-1.000) with a sensitivity of 92% and specificity of 85.7%. CRKP BSI was a significant mortality risk in premature infants. It is crucial to administer proper antimicrobial therapy in order to increase survival rates of the patients. CAZ/AVI has the potential to improve outcomes in this particular population; however, further research is required to evaluate the effectiveness of specific treatment in premature infants.

Performance of Risk Models for Antimicrobial Resistance in Adult Patients With Sepsis

Importance

The results of prediction models that stratify patients with sepsis and risk of resistant gram-negative bacilli (GNB) infections inform treatment guidelines. However, these models do not extrapolate well across hospitals.

Objective

To assess whether patient case mix and local prevalence rates of resistance contributed to the variable performance of a general risk stratification GNB sepsis model for community-onset and hospital-onset sepsis across hospitals.

Design, Setting, and Participants

This was a retrospective cohort study conducted from January 2016 and October 2021. Adult patients with sepsis at 10 acute-care hospitals in rural and urban areas across Missouri and Illinois were included. Inclusion criteria were blood cultures indicating sepsis, having received 4 days of antibiotic treatment, and having organ dysfunction (vasopressor use, mechanical ventilation, increased creatinine or bilirubin levels, and thrombocytopenia). Analyses were completed in April 2024.

Exposure

The model included demographic characteristics, comorbidities, vital signs, laboratory values, procedures, and medications administered.

Main Outcomes and Measures

Culture results were stratified for ceftriaxone-susceptible GNB (SS), ceftriaxone-resistant but cefepime-susceptible GNB (RS), and ceftriaxone- and cefepime-resistant GNB (RR). Negative cultures and other pathogens were labeled SS. Deep learning models were developed separately for community-onset (patient presented with sepsis) and hospital-onset (sepsis developed ≥48 hours after admission) sepsis. The models were tested across hospitals and patient subgroups. Models were assessed using area under the receiver operating characteristic curve (AUROC) and area under precision recall curve (AUPRC).

Results

A total of 39 893 patients with 85 238 sepsis episodes (43 207 [50.7%] community onset; 42 031 [48.3%] hospital onset) were included. Median (IQR) age was 65 (54-74) years, 21 241 patients (53.2%) were male, and 18 830 (47.2%) had a previous episode of sepsis. RS contributed to 3.9% (1667 episodes) and 5.7% (2389 episodes) of community-onset and hospital-onset sepsis episodes, respectively, and RR contributed to 1.8% (796 episodes) and 3.9% (1626 episodes), respectively. Previous infections and exposure to antibiotics were associated with the risk of resistant GNB. For example, in community-onset sepsis, 375 RR episodes (47.1%), 420 RS episodes (25.2%) and 3483 of 40 744 (8.5%) SS episodes were among patients with resistance to antimicrobial drugs (P < .001). The AUROC and AUPRC results varied across hospitals and patient subgroups for both community-onset and hospital-onset sepsis. AUPRC values correlated with the prevalence rates of resistant GNB (R = 0.79; P = .001).

Conclusions and Relevance

In this cohort study of 39 893 patients with sepsis, variable model performance was associated with prevalence rates of antimicrobial resistance rather than patient case mix. This variability suggests caution is needed when using generalized models for predicting resistant GNB etiologies in sepsis.

Microbial dynamics, risk factors and outcomes of secondary pneumonia in critically ill patients with COVID-19: A multicenter retrospective cohort study

BACKGROUND

Secondary pneumonia has a significant clinical impact on critically ill patients with COVID-19.

AIM

Considering potential geographic variations, this study explores the clinical implications of secondary pneumonia within East Asian populations.

METHODS

This multicenter, retrospective cohort study enrolled critical COVID-19 patients requiring intensive care units (ICUs) admission in Taiwan from December 31, 2020, to June 1, 2022.

FINDINGS

Among the 187 critical COVID-19 patients, 80 (42.8%) developed secondary pneumonia. The primary causative pathogens were gram-negative bacilli (GNB) (76.8%). Gram-positive cocci and fungi were mainly observed during the initial two weeks of ICU stay. Notably, the incidence of pulmonary aspergillosis was 9.2% during the first week of ICU stay and all Staphylococcus aureus were susceptible to methicillin. Multi-drug resistant organisms (MDROs) were responsible for 28.3% of the cases, exhibiting significantly longer ICU stays compared to the non-MDRO group (median, 27 vs. 14 days, P < 0.001). In the multivariate analysis, Acute Physiology and Chronic Health Evaluation II (APACHE II) and Sequential Organ Failure Assessment (SOFA) scores were associated with a significantly increased risk of secondary pneumonia. In-hospital mortality was significantly higher in patients with secondary pneumonia than in those without (37.7% vs. 16.7%, P = 0.02) and survival analysis demonstrated gram-negative bacilli-related secondary pneumonia contributed to a worse prognosis.

CONCLUSION

Secondary pneumonia in critical COVID-19 patients significantly raised in-hospital mortality and extended hospital and ICU stays. Moreover, the presence of GNB notably predicted an unfavorable prognosis.

Effectiveness of short treatment duration for carbapenemase-producing Enterobacterales in bloodstream-infections: A retrospective cohort study

OBJECTIVE

We analyse the effectiveness of short courses of adequate treatment in patients with episodes of carbapenemase-producing Enterobacterales bloodstream-infections (CPE-BSI).

METHODS

Patients with first monomicrobial CPE-BSI episodes who received ≥72 h of appropriate treatment from 2014-2022 were selected. Detection of CPE was established on the basis of phenotypic antibiogram and confirmation by PCR and/or immunochromatographic methods. Patients were classified in short treatment group (STG) those who received 3-10 days of appropriate treatment, and long treatment (LTG) those receiving >10 days. Unfavourable outcome consisted in a composite of global 30-day mortality and/or persistent bacteremia and/or recurrent bacteremia. Inverse probability of treatment weighting (IPTW) analysis was performed to compare the outcome between the two study groups.

RESULTS

We included 105 CPE-BSI episodes: 99 were caused by OXA-48-like, 4 VIM and 2 KPC carbapenemases. Thirty-nine patients (37.1%) were included in the STG and 66 (62.9%) in LTG. The STG group presented frequent treatment with ceftazidime-avibactam (43.6% vs. 24.2%, P = 0.03) and lower in-hospital stay (21 days vs. 32 days, P = 0.02). Overall, 28 patients (26.7%) presented unfavourable outcome: IPTW analysis showed no differences in the outcome between STG to LTG groups (24.2% vs. 30.8%, weighted-risk difference 6.6%, P = 0.44). Patients with unfavourable outcome presented more frequently source other than urinary-biliary (46.4% vs. 23.4%, P = 0.02), received less frequently ceftazidime-avibactam (14.3% vs. 37.7%, P = 0.02) and presented frequently with absence of source control when indicated (28.6% vs. 13.0%, P = 0.06).

CONCLUSIONS

Short treatment durations for CPE-BSI episodes may be effective, as long as they are appropriate and source control is performed.

Early antibiotic de-escalation in patients with severe infections due to bloodstream infection by enterobacterales: A post hoc analysis of a prospective multicentre cohort

BACKGROUND

Data about antibiotic de-escalation in sepsis associated with the bloodstream and caused by Enterobacterales are scarce. The objectives of this study are to identify factors associated with early de-escalation and to analyse the impact of de-escalation on mortality in patients with Enterobacterales bloodstream infection (BSI) with a Sequential Organ Failure Assessment (SOFA) score ≥ 2.

METHODS

A prospective, multicentre cohort study was performed including episodes of BSI due to Enterobacterales and a SOFA score ≥ 2 who were receiving an active antipseudomonal β-lactam; the isolate should be susceptible to at least 1 narrower-spectrum antibiotic. Variables associated with de-escalation were identified using logistic binary regression. The association of de-escalation with 30-day mortality was investigated. Confounding was controlled by calculating a propensity score used as covariate, as matching variable, and for inverse probability treatment weighting.

RESULTS

Of the 582 patients included, de-escalation was performed in 311 (53.4%). Neutropenia (adjusted odds ratio [aOR] = 0.37; 95% confidence interval [95% CI] = 0.18-0.75), central venous catheter (aOR = 0.52; 95% CI = 0.32-0.83), and extended-spectrum β-lactamase (ESBL)-producing isolate (aOR = 0.28; 95% CI = 0.17-0.48) were negatively associated with de-escalation, and urinary tract source was positively associated (aOR = 2.27; 95% CI = 1.56-3.33). The 30-day mortality was 6.8% (21 patients) in de-escalated patients and 14.4% (39) in not de-escalated patients (relative risk, 0.63; 95% CI = 0.44-0.89). In multivariate analysis including the propensity score, de-escalation was not associated with mortality (AOR = 0.98; 95% CI = 0.39-2.47) and was protective in the case of urinary or biliary tract source (AOR = 0.31, 95% CI = 0.09-1.06). Matched and inverse probability treatment weighting analysis showed similar results.

CONCLUSIONS

These results suggest that early de-escalation from antipseudomonal β-lactams is safe in patients with Enterobacterales bacteremia and SOFA ≥ 2.

Association Between Infectious Diseases Consultation and Mortality in Hospitalized Patients With Gram-negative Bloodstream Infection: A Retrospective Population-wide Cohort Study

OBJECTIVES

Data supporting routine infectious diseases (ID) consultation in gram-negative bloodstream infection (GN-BSI) are limited. We evaluated the association between ID consultation and mortality in patients with GN-BSI in a retrospective population-wide cohort study in Ontario using linked health administrative databases.

METHODS

Hospitalized adult patients with GN-BSI between April 2017 and December 2021 were included. The primary outcome was time to all-cause mortality censored at 30 days, analyzed using a mixed effects Cox proportional hazards model with hospital as a random effect. ID consultation 1-10 days after the first positive blood culture was treated as a time-varying exposure.

RESULTS

Of 30 159 patients with GN-BSI across 53 hospitals, 11 013 (36.5%) received ID consultation. Median prevalence of ID consultation for patients with GN-BSI across hospitals was 35.0% with wide variability (range 2.7%-76.1%, interquartile range 19.6%-41.1%). In total, 1041 (9.5%) patients who received ID consultation died within 30 days, compared to 1797 (9.4%) patients without ID consultation. In the fully adjusted multivariable model, ID consultation was associated with mortality benefit (adjusted hazard ratio [HR] 0.82, 95% confidence interval [CI] .77-.88, P < .0001; translating to absolute risk reduction of -3.8% or number needed to treat [NNT] of 27). Exploratory subgroup analyses of the primary outcome showed that ID consultation could have greater benefit in patients with high-risk features (nosocomial infection, polymicrobial or non-Enterobacterales infection, antimicrobial resistance, or non-urinary tract source).

CONCLUSIONS

Early ID consultation was associated with reduced mortality in patients with GN-BSI. If resources permit, routine ID consultation for this patient population should be considered to improve patient outcomes.

Risk Factors and Outcomes of Patients with Pseudomonas aeruginosa Bloodstream Infection in the Intensive Care Unit

Background: Bloodstream infections (BSIs) caused by Pseudomonas aeruginosa have high mortality rates and pose a significant threat to healthcare settings. Objectives: We aimed to investigate the clinical risk factors related to mortality and the development of P. aeruginosa with difficult-to-treat resistance (DTR-PA) BSI in the intensive care unit. Methods: This was a retrospective, single-center study that included patients with P. aeruginosa BSI who were hospitalized between 2020 and 2022. The risk factors affecting 30-day mortality and the development of DTR-PA were investigated using both univariate and multivariate analyses. Results: A total of 140 patients were analyzed. The mean age was (66 ± 17.5) years, and 48% of the patients were male. Previous meropenem use was an independent risk factor for DTR-PA BSI (odds ratio, 2.68; 95% CI, 1.24 to 5.80; P = 0.012). Multivariate analysis demonstrated that the requirement for inotropic support was an independent risk factor for 30-day mortality [hazard ratio, 2.50; 95% confidence interval (CI), 1.33 to 4.68; P = 0.004]. Conclusions: Prior meropenem use was an independent risk factor for DTR-PA development. Strict policies for Carbapenem use and infection control procedures are essential to combat infections caused by DTR-PA.

Diagnostic and therapeutic yield of imaging studies in Polymicrobial and Monomicrobial Gram-negative bloodstream infections - a retrospective cohort study

PURPOSE

Appropriate antimicrobial therapy and surgical drainage, improve survival in patients with Gram negative bloodstream infections (BSI). Data about the yield of imaging studies in polymicrobial BSI is sparse. The aim of the study was to assess the need for imaging studies and surgical drainage among patients with polymicrobial compared to monomicrobial BSI.

RESULTS

In a retrospective cohort study of adult patients with Gram negative BSI, 135 patients with monomicrobial BSI were compared to 82 with polymicrobial BSI. Imaging studies were performed in 56.3 % of patients with monomicrobial BSI and in 50 % of polymicrobial BSI (p=0.4), surgical drainage was performed in 20.1 % of patients with monomicrobial BSI and 27.2 % of polymicrobial BSI (p=0.25). Surgical drainage was performed in 26.2 % of patients who survived vs. 11.8 % of patients who died (p=0.035).

CONCLUSIONS

There is no difference in the diagnostic approach to monomicrobial and polymicrobial Gram-negative BSI. Surgical drainage is associated with decreased mortality.

The impact of meropenem shortage and post-prescription review and feedback on broad-spectrum antimicrobial use: An interrupted time-series analysis

Background

Meropenem (MEPM) holds significance in treating severe infections and drug-resistant bacteria. There are concerns that antimicrobial shortages may lead to the use of alternative antimicrobials that are less effective and safer. We have responded to the MEPM shortage with post-prescription monitoring and feedback (PPRF) with no restrictions on MEPM initiation. We aimed to assess the impact of the MEPM shortage and the PPRF on broad-spectrum antimicrobial use and mortality.

Methods

This retrospective study was conducted in a single hospital in Japan. The period from October 2021 to August 2022 was defined as the period before the MEPM shortage, and the period from September 2022 to March 2023 was defined as the period during the MEPM shortage. To support the appropriate use of antimicrobials during MEPM shortages, the antimicrobial stewardship team (AST) developed a list of alternatives to MEPM. An interrupted time series analysis was used to assess changes in use and mortality among patients receiving broad-spectrum antimicrobials over the study period.

Discussion

The shortage of MEPM and PPRF temporarily increased the use of alternative cefepime; however, the subsequent change in days of therapy and days of coverage of broad-spectrum antimicrobials suggests a decrease in the use of these antimicrobials. Despite these shifts, the mortality rates remained stable, suggesting that the response to the shortage did not adversely affect treatment outcomes.

Conclusion

In the context of antimicrobial shortages, AST support plays an important role in enabling physicians to make optimal use of antimicrobials.

Rapid Diagnostic Tests and Antimicrobial Stewardship Programs for the Management of Bloodstream Infection: What Is Their Relative Contribution to Improving Clinical Outcomes? A Systematic Review and Network Meta-analysis

BACKGROUND

Evidence about the clinical impact of rapid diagnostic tests (RDTs) for the diagnosis of bloodstream infections is limited, and whether RDT are superior to conventional blood cultures (BCs) embedded within antimicrobial stewardship programs (ASPs) is unknown.

METHODS

We performed network meta-analyses using results from studies of patients with bloodstream infection with the aim of comparing the clinical impact of RDT (applied on positive BC broth or whole blood) to conventional BC, both assessed with and without ASP with respect to mortality, length of stay (LOS), and time to optimal therapy.

RESULTS

Eighty-eight papers were selected, including 25 682 patient encounters. There was an appreciable amount of statistical heterogeneity within each meta-analysis. The network meta-analyses showed a significant reduction in mortality associated with the use of RDT + ASP versus BC alone (odds ratio [OR], 0.72; 95% confidence interval [CI], .59-.87) and with the use of RDT + ASP versus BC + ASP (OR, 0.78; 95% CI, .63-.96). No benefit in survival was found associated with the use of RDT alone nor with BC + ASP compared to BC alone. A reduction in LOS was associated with RDT + ASP versus BC alone (OR, 0.91; 95% CI, .84-.98) whereas no difference in LOS was shown between any other groups. A reduced time to optimal therapy was shown when RDT + ASP was compared to BC alone (-29 hours; 95% CI, -35 to -23), BC + ASP (-18 hours; 95% CI, -27 to -10), and to RDT alone (-12 hours; 95% CI, -20 to -3).

CONCLUSIONS

The use of RDT + ASP may lead to a survival benefit even when introduced in settings already adopting effective ASP in association with conventional BC.

Outcomes of inadequate empiric therapy and timing of newer antibacterial therapy in hospitalized adults with culture-positive Enterobacterales and Pseudomonas aeruginosa: a multicenter analysis

BACKGROUND

Infections caused by multi-drug resistant Gram-negative pathogens are associated with worse clinical outcomes in critically ill patients. We evaluated hospital outcomes based on adequacy of overall and newer antibacterial therapy for Enterobacterales (ENT) and Pseudomonas aeruginosa (PsA) in US patients.

METHODS

Hospitalized adults ≥ 18 years old with facility-reported antibiotic susceptibility from 2018-2022 across 161 facilities in the BD Insights Research Database were identified as ENT- or PsA-positive. Generalized linear mixed models were used to evaluate the impact of inadequate empiric therapy (IET) and time to initiate newer antibacterials (ceftazidime-avibactam; ceftolozane-tazobactam; cefiderocol; meropenem-vaborbactam; eravacycline; and imipenem-cilcastatin-relebactam) on hospital mortality and post-culture length of stay (LOS).

RESULTS

Among 229,320 ENT and 36,027 PsA susceptibility results, 1.7% and 16.8% were carbapenem non-susceptible (carb-NS), respectively. Median time to first susceptibility result was longer for carb-NS vs. carb susceptible in ENT (64 h vs. 48 h) and PsA (67 h vs. 60 h). For ENT, IET was associated with significantly higher mortality (odds ratio [OR],1.29 [95% CI, 1.16-1.43, P < 0.0001]) and longer hospital LOS (14.8 vs. 13.3, P < 0.0001). Delayed start to newer antibacterial therapy was associated with significantly greater hospital mortality for ENT (P = 0.0182) and PsA (P = 0.0249) and significantly longer post-culture LOS for ENT (P < 0.0001) and PsA (P < 0.0001).

CONCLUSIONS

Overall, IET and delayed use of newer antibacterials are associated with significantly worse hospital outcomes. More rapid identification of high-risk patients can facilitate adequate therapy and timely use of newer antibacterials developed for resistant Gram-negative pathogens.

Hospital mortality and length of stay associated with Enterobacterales positive blood cultures: a multicenter analysis

Delayed time to antimicrobial susceptibility results can impact patients' outcomes. Our study evaluated the impact of susceptibility turnaround time (TAT) and inadequate empiric antibacterial therapy (IET) in patients with bloodstream infections (BSI) caused by Enterobacterales (ENT) species on in-hospital mortality and length of stay (LOS). This retrospective, multicenter investigation which included 29,570 blood ENT-positive admissions across 161 US healthcare facilities evaluated the association between antimicrobial susceptibility testing (AST) TAT, carbapenem susceptibility, and empiric therapy on post-BSI in-hospital mortality and LOS following an ENT BSI event in adult patients. After adjusting for outcomes covariates, post-BSI in-hospital mortality was significantly higher for patients in the IET vs adequate empiric therapy (AET) group [odds ratio (OR): 1.61 (95% CI: 1.32, 1.98); P < 0.0001], and when AST TAT was >63 h [OR:1.48 (95% CI: 1.16, 1.90); P = 0.0017]. Patients with carbapenem non-susceptible (carb-NS) ENT BSI had significantly higher LOS (16.6 days, 95% CI: 15.6, 17.8) compared to carbapenem susceptible (carb-S, 12.2 days, 95% CI: 11.8, 12.6), (P < 0.0001). Extended AST TAT was significantly associated with longer LOS for TAT of 57-65 h and >65 h (P = 0.005 and P< 0.0001, respectively) compared to TAT ≤42 h (reference). Inadequate empiric therapy (IET), carb-NS, and delayed AST TAT are significantly associated with adverse hospital outcomes in ENT BSI. Workflows that accelerate AST TAT for ENT BSIs and facilitate timely and adequate therapy may reduce post-BSI in-hospital mortality rate and LOS.IMPORTANCEFor patients diagnosed with bloodstream infections (BSI) caused by Enterobacterales (ENT), delayed time to antimicrobial susceptibility (AST) results can significantly impact in-hospital mortality and hospital length of stay. However, this relationship between time elapsed from blood culture collection to AST results has only been assessed, to date, in a limited number of publications. Our study focuses on this important gap using retrospective data from 29,570 blood ENT-positive admissions across 161 healthcare facilities in the US as we believe that a thorough understanding of the dynamic between AST turnaround time, adequacy of empiric therapy, post-BSI event mortality, and hospital length of stay will help guide effective clinical management and optimize outcomes of patients with ENT infections.

Association of microbiological factors with mortality in Escherichia coli bacteraemia presenting with sepsis/septic shock: a prospective cohort study

OBJECTIVES

This study aimed to determine the association of Escherichia coli microbiological factors with 30-day mortality in patients with bloodstream infection (BSI) presenting with a dysregulated response to infection (i.e. sepsis or septic shock).

METHODS

Whole-genome sequencing was performed on 224 E coli isolates of patients with sepsis/septic shock, from 22 Spanish hospitals. Phylogroup, sequence type, virulence, antibiotic resistance, and pathogenicity islands were assessed. A multivariable model for 30-day mortality including clinical and epidemiological variables was built, to which microbiological variables were hierarchically added. The predictive capacity of the models was estimated by the area under the receiver operating characteristic curve (AUROC) with 95% confidence intervals (CI).

RESULTS

Mortality at day 30 was 31% (69 patients). The clinical model for mortality included (adjusted OR; 95% CI) age (1.04; 1.02-1.07), Charlson index ≥3 (1.78; 0.95-3.32), urinary BSI source (0.30; 0.16-0.57), and active empirical treatment (0.36; 0.11-1.14) with an AUROC of 0.73 (95% CI, 0.67-0.80). Addition of microbiological factors selected clone ST95 (3.64; 0.94-14.04), eilA gene (2.62; 1.14-6.02), and astA gene (2.39; 0.87-6.59) as associated with mortality, with an AUROC of 0.76 (0.69-0.82).

DISCUSSION

Despite having a modest overall contribution, some microbiological factors were associated with increased odds of death and deserve to be studied as potential therapeutic or preventive targets.

Management of Immunosuppressive Therapy in Kidney Transplant Recipients with Sepsis: A Multicenter Retrospective Study

BACKGROUND

Up to 6% of kidney transplant recipients (KTRs) experience life-threatening complications requiring intensive care unit (ICU) admission, and one of the most common medical complications requiring ICU admission is infection. This study aimed to evaluate the effect of immunosuppressive therapy (IST) modification on prognosis of KTRs with sepsis.

METHODS

We conducted a multicenter retrospective study in 4 university-affiliated hospitals to evaluate the effect of adjusting the IST in KTRs with sepsis. Only patients who either maintained IST after ICU admission or those who underwent immediate (within 24 h of ICU admission) reduction or withdrawal of IST following ICU admission were included in this study. "Any reduction" was defined as a dosage reduction of any IST or discontinuation of at least 1 IST. "Complete withdrawal of IST" was defined as concomitant discontinuation of all ISTs, except steroids.

RESULTS

During the study period, 1596 of the KTRs were admitted to the ICU, and 112 episodes of sepsis or septic shock were identified. The overall in-hospital mortality rate was 35.7%. In-hospital mortality was associated with higher sequential organ failure assessment score, simplified acute physiology score 3, non-identical human leukocyte antigen relation, presence of septic shock, and complete withdrawal of IST. After adjusting for potential confounding factors, complete withdrawal of IST remained significantly associated with in-hospital mortality (adjusted coefficient, 1.029; 95% confidence interval, 0.024-2.035) and graft failure (adjusted coefficient, 2.001; 95% confidence interval, 0.961-3.058).

CONCLUSIONS

Complete IST withdrawal was common and associated with worse outcomes in critically ill KTRs with sepsis.

Mortality impact of further delays in active targeted antibiotic therapy in bacteraemic patients that did not receive initial active empiric treatment: Results from the prospective, multicentre cohort PROBAC

OBJECTIVES

The early initiation of the empirical antibiotic treatment and its impact on mortality in patients with bacteraemia has been extensively studied. However, information on the impact of precocity of the targeted antibiotic treatment is scarce. We aimed to study the impact of further delay in active antibiotic therapy on 30-day mortality among patients with bloodstream infection who had not received appropriate empirical therapy.

DESIGN

We worked with PROBAC cohort (prospective and compound by patients from 26 different Spanish hospitals). We selected a total of 1703 patients, who survived to day 2 without having received any active antibiotic therapy against the causative pathogen.

RESULTS

The 30-day mortality was 14% (238 patients). The adjusted odds of mortality increased for every day of delay, from 1.53 (95% confidence interval (CI) 1.13-2.08) for day 3 or after to 11.38 (95% CI 7.95-16.38) for day 6 or after.

CONCLUSION

We concluded that among patients who had not received active treatment within the first 2 days of blood culture collection, additional delays in active targeted therapy were associated with increased mortality. These results emphasize the importance of active interventions in the management of patients with bloodstream infections.

Epidemiology and clinical relevance of persistent bacteraemia in patients with Gram-negative bloodstream infection: a retrospective cohort study

OBJECTIVES

The risk factors and outcomes associated with persistent bacteraemia in Gram-negative bloodstream infection (GN-BSI) are not well described. We conducted a follow-on analysis of a retrospective population-wide cohort to characterize persistent bacteraemia in patients with GN-BSI.

METHODS

We included all hospitalized patients >18 years old with GN-BSI between April 2017 and December 2021 in Ontario who received follow-up blood culture (FUBC) 2-5 days after the index positive blood culture. Persistent bacteraemia was defined as having a positive FUBC with the same Gram-negative organism as the index blood culture. We identified variables independently associated with persistent bacteraemia in a multivariable logistic regression model. We evaluated whether persistent bacteraemia was associated with increased odds of 30- and 90-day all-cause mortality using multivariable logistic regression models adjusted for potential confounders.

RESULTS

In this study, 8807 patients were included; 600 (6.8%) had persistent bacteraemia. Having a permanent catheter, antimicrobial resistance, nosocomial infection, ICU admission, respiratory or skin and soft tissue source of infection, and infection by a non-fermenter or non-Enterobacterales/anaerobic organism were associated with increased odds of having persistent bacteraemia. The 30-day mortality was 17.2% versus 9.6% in those with and without persistent bacteraemia (aOR 1.65, 95% CI 1.29-2.11), while 90-day mortality was 25.5% versus 16.9%, respectively (aOR 1.53, 95% CI 1.24-1.89). Prevalence and odds of developing persistent bacteraemia varied widely depending on causative organism.

CONCLUSIONS

Persistent bacteraemia is uncommon in GN-BSI but is associated with poorer outcomes. A validated risk stratification tool may be useful to identify patients with persistent bacteraemia.

Proteomic assay for rapid characterisation of Staphylococcus aureus antimicrobial resistance mechanisms directly from blood cultures

PURPOSE

Staphylococcus aureus is one of the most common pathogens causing bloodstream infection. A rapid characterisation of resistance to methicillin and, occasionally, to aminoglycosides for particular indications, is therefore crucial to quickly adapt the treatment and improve the clinical outcomes of septic patients. Among analytical technologies, targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) has emerged as a promising tool to detect resistance mechanisms in clinical samples.

METHODS

A rapid proteomic method was developed to detect and quantify the most clinically relevant antimicrobial resistance effectors in S. aureus in the context of sepsis: PBP2a, PBP2c, APH(3')-III, ANT(4')-I, and AAC(6')-APH(2''), directly from positive blood cultures and in less than 70 min including a 30-min cefoxitin-induction step. The method was tested on spiked blood culture bottles inoculated with 124 S.aureus, accounting for the known genomic diversity of SCCmec types and the genetic background of the strains.

RESULTS

This method provided 99% agreement for PBP2a (n = 98/99 strains) detection. Agreement was 100% for PBP2c (n = 5/5), APH(3')-III (n = 16/16), and ANT(4')-I (n = 20/20), and 94% for AAC(6')-APH(2'') (n = 16/17). Across the entire strain collection, 100% negative agreement was reported for each of the 5 resistance proteins. Additionally, relative quantification of ANT(4')-I expression allowed to discriminate kanamycin-susceptible and -resistant strains, in all strains harbouring the ant(4')-Ia gene.

CONCLUSION

The LC-MS/MS method presented herein demonstrates its ability to provide a reliable determination of S. aureus resistance mechanisms, directly from positive blood cultures and in a short turnaround time, as required in clinical laboratories.

Community-acquired pneumonia: The importance of the early detection of drug-resistant organisms

Pneumonia is a disease associated with significant healthcare burden with over 1.5 million hospitalizations annually and is the eighth leading cause of death in the United States. While community-acquired pneumonia (CAP) is generally considered an acute time-limited illness, it is associated with high long-term mortality, with nearly one-third of patients requiring hospitalization dying within one year. An increasing trend of detecting multidrug-resistant (MDR) organisms causing CAP has been observed, especially in the Western world. In this editorial, we discuss about a publication by Jatteppanavar et al which reported that a case of a MDR organism was the culprit in developing pneumonia, bacteremia, and infective endocarditis that led to the patient's death. The early detection of these resistant organisms helps improve patient outcomes. Significant advances have been made in the biotechnological and research space, but preventive measures, diagnostic techniques, and treatment strategies need to be developed.

Epidemiology and antimicrobial susceptibility profiles of Enterobacterales causing bloodstream infections before and during COVID-19 pandemic: Results of the Study for Monitoring Antimicrobial Resistance Trends (SMART) in Taiwan, 2018-2021

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has contributed to the spread of antimicrobial resistance, including carbapenem-resistant Enterobacterales.

METHODS

This study utilized data from the Study for Monitoring Antimicrobial Resistance Trends (SMART) surveillance program in Taiwan. Enterobacterales from patients with bloodstream infections (BSIs) were collected and subjected to antimicrobial susceptibility testing and β-lactamase gene detection using a multiplex PCR assay. Statistical analysis was conducted to compare susceptibility rates and resistance genes between time periods before (2018-2019) and during the COVID-19 pandemic (2020-2021).

RESULTS

A total of 1231 Enterobacterales isolates were collected, predominantly Escherichia coli (55.6%) and Klebsiella pneumoniae (29.2%). The proportion of nosocomial BSIs increased during the COVID-19 pandemic (55.5% vs. 61.7%, p < 0.05). Overall, susceptibility rates for most antimicrobial agents decreased, with Enterobacterales from nosocomial BSIs showing significantly lower susceptibility rates than those from community-acquired BSIs. Among 123 Enterobacterales isolates that underwent molecular resistance mechanism detection, ESBL, AmpC β-lactamase, and carbapenemase genes were detected in 43.1%, 48.8% and 16.3% of the tested isolates, respectively. The prevalence of carbapenemase genes among carbapenem-resistant Enterobacterales increased during the pandemic, although the difference was not statistically significant. Two novel β-lactamase inhibitor combinations, imipenem-relebactam and meropenem-vaborbactam, preserved good efficacy against Enterobacterales. However, imipenem-relebactam showed lower in vitro activity against imipenem-non-susceptible Enterobacterales than that of meropenem-vaborbactam.

CONCLUSIONS

The COVID-19 pandemic appears to be associated with a general decrease in antimicrobial susceptibility rates among Enterobacterales causing BSIs in Taiwan. Continuous surveillance is crucial to monitor antimicrobial resistance during the pandemic and in the future.

Efficacy and safety of a structured de-escalation from antipseudomonal β-lactams in bloodstream infections due to Enterobacterales (SIMPLIFY): an open-label, multicentre, randomised trial

BACKGROUND

De-escalation from broad-spectrum to narrow-spectrum antibiotics is considered an important measure to reduce the selective pressure of antibiotics, but a scarcity of adequate evidence is a barrier to its implementation. We aimed to determine whether de-escalation from an antipseudomonal β-lactam to a narrower-spectrum drug was non-inferior to continuing the antipseudomonal drug in patients with Enterobacterales bacteraemia.

METHODS

An open-label, pragmatic, randomised trial was performed in 21 Spanish hospitals. Patients with bacteraemia caused by Enterobacterales susceptible to one of the de-escalation options and treated empirically with an antipseudomonal β-lactam were eligible. Patients were randomly assigned (1:1; stratified by urinary source) to de-escalate to ampicillin, trimethoprim-sulfamethoxazole (urinary tract infections only), cefuroxime, cefotaxime or ceftriaxone, amoxicillin-clavulanic acid, ciprofloxacin, or ertapenem in that order according to susceptibility (de-escalation group), or to continue with the empiric antipseudomonal β-lactam (control group). Oral switching was allowed in both groups. The primary outcome was clinical cure 3-5 days after end of treatment in the modified intention-to-treat (mITT) population, formed of patients who received at least one dose of study drug. Safety was assessed in all participants. Non-inferiority was declared when the lower bound of the 95% CI of the absolute difference in cure rate was above the -10% non-inferiority margin. This trial is registered with EudraCT (2015-004219-19) and ClinicalTrials.gov (NCT02795949) and is complete.

FINDINGS

2030 patients were screened between Oct 5, 2016, and Jan 23, 2020, of whom 171 were randomly assigned to the de-escalation group and 173 to the control group. 164 (50%) patients in the de-escalation group and 167 (50%) in the control group were included in the mITT population. 148 (90%) patients in the de-escalation group and 148 (89%) in the control group had clinical cure (risk difference 1·6 percentage points, 95% CI -5·0 to 8·2). The number of adverse events reported was 219 in the de-escalation group and 175 in the control group, of these, 53 (24%) in the de-escalation group and 56 (32%) in the control group were considered severe. Seven (5%) of 164 patients in the de-escalation group and nine (6%) of 167 patients in the control group died during the 60-day follow-up. There were no treatment-related deaths.

INTERPRETATION

De-escalation from an antipseudomonal β-lactam in Enterobacterales bacteraemia following a predefined rule was non-inferior to continuing the empiric antipseudomonal drug. These results support de-escalation in this setting.

FUNDING

Plan Nacional de I+D+i 2013-2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Ciencia, Innovación y Universidades, Spanish Network for Research in Infectious Diseases; Spanish Clinical Research and Clinical Trials Platform, co-financed by the EU; European Development Regional Fund "A way to achieve Europe", Operative Program Intelligence Growth 2014-2020.

Empirical antibiotic therapy modalities for Enterobacteriaceae bloodstream infections in older patients and their impact on mortality: a multicentre retrospective study

PURPOSE

Enterobacteriaceae (EB) bloodstream infections (BSI) are frequent and serious in older patients. Physicians are faced with the dilemma of prescribing early appropriate empirical antibiotics to limit the risk of death, and sparing broad-spectrum antibiotic prescription. The aim of the study was to assess the rate of appropriate empirical antibiotics prescription to treat EB BSI in older patients and its impact on survival.

METHODS

This study conducted in 49 centres enrolled retrospectively up to the 10 last consecutive patients aged 75 years and over and treated for EB BSI. Factors related to in-hospital death were investigated using logistic regression.

RESULTS

Among the 487 enrolled patients (mean age 86 ± 5.9 years), 70% had at least one risk factor of being infected by third-generation cephalosporins (3GC)-resistant strain; however, only 13.8% of EB strains were resistant to 3GC. An empirical antimicrobial treatment was initiated for 418 patients (85.8%), and for 86% (n = 360/418) of them, it was considered appropriate. In-hospital mortality was 12.7% (n = 62) and was related to the severity of infection (OR 3.17, CI 95% 1.75-5.75), while a urinary portal of entry was protective (OR 0.34, CI 95% 0.19-0.60). Neither the absence of nor inappropriate empirical antibiotics prescription was associated with increased mortality.

CONCLUSION

While patients enrolled in this study were at risk of being infected by multidrug-resistant bacteria, yet mainly treated with 3GC, empirical antibiotics prescription was appropriate in most cases and did not influence mortality.

Association of piperacillin/tazobactam MIC and mortality in a cohort of ceftriaxone-resistant Escherichia coli bloodstream infections treated with piperacillin/tazobactam and carbapenems: a multicentric propensity score-weighted observational cohort study

OBJECTIVES

To assess the impact of piperacillin/tazobactam MICs on in-hospital 30 day mortality in patients with third-generation cephalosporin-resistant Escherichia coli bloodstream infection treated with piperacillin/tazobactam, compared with those treated with carbapenems.

METHODS

A multicentre retrospective cohort study was conducted in three large academic hospitals in Italy between 2018 and 2022. The study population comprised patients with monomicrobial third-generation cephalosporin-resistant E. coli bloodstream infection, who received either piperacillin/tazobactam or carbapenem therapy within 48 h of blood culture collection. The primary outcome was in-hospital 30 day all-cause mortality. A propensity score was used to estimate the likelihood of receiving empirical piperacillin/tazobactam treatment. Cox regression models were performed to ascertain risk factors independently associated with in-hospital 30 day mortality.

RESULTS

Of the 412 consecutive patients included in the study, 51% received empirical therapy with piperacillin/tazobactam, while 49% received carbapenem therapy. In the propensity-adjusted multiple Cox model, the Pitt bacteraemia score [HR 1.38 (95% CI, 0.85-2.16)] and piperacillin/tazobactam MICs of 8 mg/L [HR 2.35 (95% CI, 1.35-3.95)] and ≥16 mg/L [HR 3.69 (95% CI, 1.86-6.91)] were significantly associated with increased in-hospital 30 day mortality, while the empirical use of piperacillin/tazobactam was not found to predict in-hospital 30 day mortality [HR 1.38 (95% CI, 0.85-2.16)].

CONCLUSIONS

Piperacillin/tazobactam use might not be associated with increased mortality in treating third-generation cephalosporin-resistant E. coli bloodstream infections when the MIC is <8 mg/L.

Multicenter evaluation of the Selux Next-Generation Phenotyping antimicrobial susceptibility testing system

The Selux Next-Generation Phenotyping (NGP) system (Charlestown, MA) is a new antimicrobial susceptibility testing system that utilizes two sequential assays performed on all wells of doubling dilution series to determine MICs. A multicenter evaluation of the performance of the Selux NGP system compared with reference broth microdilution was conducted following FDA recommendations and using FDA-defined breakpoints. A total of 2,488 clinical and challenge isolates were included; gram-negative isolates were tested against 24 antimicrobials, and gram-positive isolates were tested against 15 antimicrobials. Data is provided for all organism-antimicrobial combinations evaluated, including those that did and did not meet FDA performance requirements. Overall very major error and major error rates were less than 1% (31/3,805 and 107/15,606, respectively), essential agreement and categorical agreement were >95%, reproducibility was ≥95%, and the average time-to-result (from time of assay start to time of MIC result) was 5.65 hours.

Molecular antimicrobial susceptibility testing in sepsis

Rapidly detecting and identifying pathogens is crucial for appropriate antimicrobial therapy in patients with sepsis. Conventional diagnostic methods have been a great asset to medicine, though they are time consuming and labor intensive. This work will enable healthcare professionals to understand the bacterial community better and enhance their diagnostic capacity by using novel molecular methods that make obtaining quicker, more precise results possible. The authors discuss and critically assess the merits and drawbacks of molecular testing and the added value of these tests, including the shift turnaround time, the implication for clinicians' decisions, gaps in knowledge, future research directions and novel insights or innovations. The field of antimicrobial molecular testing has seen several novel insights and innovations to improve the diagnosis and management of infectious diseases.

Can Decision Support Tools Improve Empiric Antibiotic Prescribing?

Decision Support Tools for Antibiotic PrescribingChoosing the right antibiotic is challenging. Unnecessarily broad-spectrum antibiotic treatment promotes antimicrobial resistance; inappropriately narrow-spectrum antibiotic use can lead to treatment failure. A cluster-randomized trial of a model-informed clinical decision support tool is proposed for guiding empiric antibiotic therapy for hospitalized patients with suspected infection.

Prevalence of Antimicrobial Resistance in Gram-Negative Bacteria Bloodstream Infections in Peru and Associated Outcomes: VIRAPERU Study

Surveillance of antimicrobial resistance among gram-negative bacteria (GNB) is of critical importance, but data for Peru are not available. To fill this gap, a non-interventional hospital-based surveillance study was conducted in 15 hospitals across Peru from July 2017 to October 2019. Consecutive unique blood culture isolates of key GNB (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter spp.) recovered from hospitalized patients were collected for centralized antimicrobial susceptibility testing, along with linked epidemiological and clinical data. A total of 449 isolates were included in the analysis. Resistance to third-generation cephalosporins (3GCs) was present in 266 (59.2%) GNB isolates. Among E. coli (n = 199), 68.3% showed 3GC resistance (i.e., above the median ratio for low- and middle-income countries in 2020 for this sustainable development goal indicator). Carbapenem resistance was present in 74 (16.5%) GNB isolates, with wide variation among species (0% in E. coli, 11.0% in K. pneumoniae, 37.0% in P. aeruginosa, and 60.8% in Acinetobacter spp. isolates). Co-resistance to carbapenems and colistin was found in seven (1.6%) GNB isolates. Empiric treatment covered the causative GNB in 63.3% of 215 cases. The in-hospital case fatality ratio was 33.3% (92/276). Pseudomonas aeruginosa species and carbapenem resistance were associated with higher risk of in-hospital death. In conclusion, an important proportion of bloodstream infections in Peru are caused by highly resistant GNB and are associated with high in-hospital mortality.

Occult Bacteremia Caused by Enterococcus-Associated Pyuria in an Elderly Man

We report a case of Enterococcus-associated pyelonephritis in a 74-year-old Parkinson's patient. He showed constipation, a mild fever, and altered consciousness. Blood cultures revealed Gram-positive cocci (GPC), prompting vancomycin treatment. Urinary Gram staining confirmed pyelonephritis, underscoring its diagnostic utility in elderly patients with vague symptoms. Enterococcus faecalis infections can be insidious, with the potential for organ abscesses and persistent fever. Due to nuanced presentations of Gram-positive infections versus Gram-negative ones, diagnosis can be delayed, risking sepsis. Gram-staining urine is vital, especially in older patients, as untreated Gram-positive bacteremia elevates mortality. Given our aging population and their comorbidities, Gram staining's role in quick antibiotic administration is crucial. Hence, its integration into community hospitals is advocated. This case emphasizes early detection and treatment of GPC infections in the elderly and endorses Gram staining for prompt diagnosis of Enterococcus-associated pyelonephritis.

Association of SARS-CoV-2 status and antibiotic-resistant bacteria with inadequate empiric therapy in hospitalized patients: a US multicenter cohort evaluation (July 2019 - October 2021)

BACKGROUND

Antibiotic usage and antibiotic resistance (ABR) patterns changed during the COVID-19 pandemic. Inadequate empiric antibiotic therapy (IET) is a significant public health problem and contributes to ABR. We evaluated factors associated with IET before and during the COVID-19 pandemic to determine the impact of the pandemic on antibiotic management.

METHODS

This multicenter, retrospective cohort analysis included hospitalized US adults who had a positive bacterial culture (specified gram-positive or gram-negative bacteria) from July 2019 to October 2021 in the BD Insights Research Database. IET was defined as antibacterial therapy within 48 h that was not active against the bacteria. ABR results were based on susceptibility testing and reports from local facilities. Multivariate analysis was used to identify risk factors associated with IET in patients with any positive bacterial culture and ABR-positive cultures, including multidrug-resistant (MDR) bacteria.

RESULTS

Of 278,344 eligible patients in 269 hospitals, 56,733 (20.4%) received IET; rates were higher in patients with ABR-positive (n = 93,252) or MDR-positive (n = 39,000) cultures (34.9% and 45.0%, respectively). Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2)-positive patients had significantly higher rates of IET (25.9%) compared with SARS-CoV-2-negative (20.3%) or not tested (19.7%) patients overall and in the ABR and MDR subgroups. Patients with ABR- or MDR-positive cultures had more days of therapy and longer lengths of stay. In multivariate analyses, ABR, MDR, SARS-CoV-2-positive status, respiratory source, and prior admissions were identified as key IET risk factors.

CONCLUSIONS

IET remained a persistent problem during the COVID-19 pandemic and occurred at higher rates in patients with ABR/MDR bacteria or a co-SARS-CoV-2 infection.