ESCMID 2026: Highlights from Day 4
Predicting Antibiotic Resistance Risk in Urinary Tract Infections Using Machine Learning to Support Safer Empirical Prescribing in Hospitalised Children and Adults
Presenter: Lina Aerts
This study developed and evaluated machine learning (ML) models to predict antibiotic resistance in urinary tract infections across adult and paediatric hospital populations. Electronic health records (2018–2025) from two Swiss hospitals were used. Models included demographic, clinical, and infection-related variables and were developed separately for adults and children, with assessment of cross-population transferability.
E. coli was the most common pathogen (52.3% adults; 66.9% children). Resistance prevalence varied widely: 4% (nitrofurantoin) to 49% (cefuroxime) in adults, and 2% (fosfomycin) to 24% (trimethoprim–sulfamethoxazole) in children.
Model performance:
- Adults: AUROC 0.65±0.01 (cotrimoxazole), 0.71±0.01 (ciprofloxacin), 0.76±0.01 (amoxicillin–clavulanate)
- Children: Lower and more variable performance, e.g. 0.69±0.14 (ciprofloxacin) and 0.60±0.16 (amoxicillin–clavulanate)
Prior resistance history was the strongest predictor, with male sex associated with slightly higher predicted risk. Adult-trained models showed partial transferability to paediatric data (e.g. AUROC 0.65 for amoxicillin–clavulanate).
Overall, ML models demonstrated moderate predictive ability for antibiotic resistance using routine clinical data.
Clinical, Laboratory and Financial Evaluation of Diagnostic Testing for Invasive Aspergillus Infections in Haemato-Oncology Patients with Neutropenic Fever in A Large U.K. Teaching Hospital
Presenter: James Moore
This single-centre study evaluated the diagnostic performance and cost-benefit of serum Aspergillus galactomannan (AGM) and respiratory Aspergillus PCR in neutropenic haemato-oncology patients. A total of 1,187 AGM samples from 733 patients were analysed. Overall positivity was 3.1% (37/1187). Of these, 860 (73%) were serum samples and 327 (28%) bronchoalveolar lavage fluid (BALF). Positivity rates were 1.0% for serum and 8.6% for BALF. Among haemato-oncology patients, 432 samples (36%) were tested, with serum AGM positivity <0.5%.
In patients with positive serum AGM, clinical assessment and CT findings were sufficient to guide treatment. In patients with negative serum AGM (n=50), results had minimal impact on clinical decision-making. PCR detected A. fumigatus at very low concentrations (down to 10⁻⁸ dilution) and identified A. terreus. It was positive in 12/13 BALF samples with confirmed Aspergillus infection.
Reducing serum AGM testing by 20% would offset the cost of implementing BALF PCR. Overall, BALF PCR combined with AGM showed better diagnostic performance, while serum AGM alone had limited utility.
Diagnostic Value of Galactomannan in Tracheobronchial Aspirate for Aspergillus Infection in Lung Transplant Recipients (The GALACTBAS Study)
Presenter: Arnau Monforte Pallares
This retrospective single-centre study evaluated the diagnostic performance of tracheobronchial aspirate (TBA) galactomannan (GM) compared with bronchoalveolar lavage fluid (BALF) GM in lung transplant recipients. A total of 545 paired TBA–BALF samples from 282 patients were analysed. Proven or probable Aspergillus infection was identified in 22 samples (4%).
Diagnostic performance:
- TBA GM (cut-off ≥0.54 ODI): sensitivity 95.2%, specificity 92%, AUC 0.97 (95% CI 0.95–0.99)
- BALF GM (cut-off ≥1.0 ODI): sensitivity 33.3%, specificity 99.6%, AUC 0.88 (95% CI 0.80–0.95)
TBA cultures were more frequently positive than BALF (24% vs 9.9%). TBA and BALF GM values showed moderate correlation (r = 0.54). Combined testing with concordant results improved diagnostic accuracy to 99.6%.
Overall, TBA GM showed higher sensitivity than BALF GM while maintaining high specificity.
Fungal Diagnostic Approach Among Hospitalised Patients Receiving Polyene vs Azole in US, 2021-2024
Presenter: Emma Harvey
This multicentre retrospective cohort study assessed the use of diagnostic tests for identifying fungal pathogens in hospitalized patients treated with polyenes or azoles.
A total of 12,456 patients received polyenes (96.4% liposomal amphotericin B) and 18,741 received azoles (78.0% voriconazole) across ~900 hospitals. Polyene-treated patients were younger (median 55 vs 62 years), more often male (63.5% vs 57.6%), Hispanic (17.2% vs 14.6%), and had higher HIV/AIDS prevalence (14.6% vs 2.2%). Azole-treated patients more frequently had hematologic (24.8% vs 15.5%) and solid organ malignancies (9.2% vs 6.3%). Community-acquired infections were more common with polyenes (41.4% vs 29.7%).
Among ~300 hospitals with microbiology data, 57.5% (2,158/3,755) of polyene and 59.8% (3,450/5,770) of azole patients underwent culture testing. A fungal pathogen was identified in 506 polyene and 709 azole patients. Common sources were blood and cerebrospinal fluid (polyenes) and lung and blood (azoles). Aspergillus spp. were most frequent, followed by Cryptococcus neoformans and Histoplasma capsulatum.
Biomarker testing showed that galactomannan was used more often in azole-treated patients, while beta-D-glucan and PCR were less commonly used overall. Overall, fungal pathogens were infrequently identified despite antifungal use, and advanced diagnostics remained underutilized.
Outbreak of Carbapenemase-Carrying Plasmids in Urology: Implications of Bladder Irrigation Pipe Systems
Presenter: Ana Freijo Cancio
This study investigated sporadic cases of VIM-producing Enterobacteriaceae (VPE) and identified environmental reservoirs using molecular tracing.
Following initial sporadic ICU cases and two primary care cases of VIM-1-producing Citrobacter freundii, a total of 31 cases were detected. Surveillance included 107 patients, environmental sampling (operating theatre n=10, sink syphons n=14, cystoscopes n=2), and later bladder irrigation pipes.
The median time between bladder irrigation and VPE detection was 25.5 days (range 1–238). Three carriers (2.8%) were identified. Environmental sampling showed negative results for surfaces and syphons, while 1 cystoscope and 7/33 (21.1%) irrigation pipes were positive.
A total of 64 VPE isolates were identified. The predominant clone was Serratia sarumanii ST1008 (63%). All isolates harboured a common IncF K7:A-:B- plasmid, with >90% homology across sequenced samples.
After disinfection of irrigation pipes with peracetic acid, no new cases were detected. Overall, molecular typing identified a shared plasmid across species, linking infections to an environmental reservoir.
NANOMUR: Innovative Nanomotion Technology for Antibiotic Susceptibility Testing: A Game-Changer for Urinary Tract Infections?
Presenter: Alexandre Delfino
This study evaluated an innovative nanomotion-based approach combined with machine learning (ML) to accelerate antibiotic susceptibility testing (AST) for urinary tract infections, aiming to overcome delays associated with culture-based methods.
A total of 81 monomicrobial urine samples were analysed. Initial evaluation using a model trained on spiked blood samples showed 82.72% (67/81) accuracy, 85.92% (61/71) sensitivity, and 60% (6/10) specificity. When models were trained directly on urine sample data, performance improved significantly. The best-performing model, a multilayer perceptron, achieved 95.06% accuracy, 97.18% sensitivity, and 80% specificity.
Nanomotion markedly reduced diagnostic turnaround time, delivering results in a median of 4.4 hours, compared with 37.5 hours using routine diagnostics (culture and VITEK2).
Overall, nanomotion demonstrated strong diagnostic performance and a substantial reduction in time-to-results when combined with optimized ML models.
Not All MIC Plates Are Equal: Method-Driven Shifts in Cefiderocol Susceptibility for NDM-Producing Enterobacterales
Presenter: Mélanie Bouillon
This study compared two methods for determining cefiderocol minimum inhibitory concentrations (MICs) in NDM-producing Enterobacterales (EBNDM), where accurate susceptibility testing is critical for treatment decisions. A total of 29 isolates across 8 species were analysed, including 21 ESBL-producing strains. MICs were measured using a commercial UMIC® assay and an in-house broth microdilution (BDM) method.
Results:
- MIC50: 4 mg/L (UMIC) vs 2 mg/L (BDM)
- MIC90: 8 mg/L for both methods
- EUCAST susceptibility: 48% (UMIC) vs 72% (BDM)
- CLSI susceptibility: 83% (UMIC) vs 86% (BDM)
A consistent discrepancy was observed for all NDM-7 isolates (n=3). Overall agreement between methods was 48%, with a kappa coefficient of 0.34, indicating low concordance. No specific resistance profile or strain type explained the variability.
Overall, significant differences between testing methods may impact clinical interpretation of cefiderocol susceptibility.
Rethinking ESBL Detection in Enterobacterales: Comparison if EUCAST And CLSI Guidelines and Development of a Clavulanate-Free Algorithm
Presenter: Linea Katharina Muhsal
This study compared EUCAST and CLSI methods for detecting ESBLs in Enterobacterales using whole genome sequencing (WGS) as the reference standard and evaluated a new machine learning–based algorithm.
A total of 231 isolates were analysed.
- CLSI CDT: sensitivity 80.3% (CI 72.2–87.0%), specificity 62.2% (CI 44.8–77.5%) across four species
- EUCAST CDT: sensitivity 42.7% (CI 34.6–51.0%), specificity 91.4% (CI 83.0–96.5%)
- Restricting EUCAST to the same species slightly improved sensitivity to 47.5% with specificity 83.8%
Proteus mirabilis was particularly challenging due to apparent ceftazidime susceptibility despite ESBL presence.
A new clavulanate-free algorithm based on ceftazidime, cefepime, and cefoxitin achieved:
- Internal validation: sensitivity 97.3%, specificity 60.0%
- External validation (n=201): sensitivity 97.0%, specificity 91.9%
Overall, existing methods showed limitations, while the new algorithm demonstrated high sensitivity and improved real-world specificity.
Development of a Non-Invasion Intranasal Vaccine for Klebsiella Pneumoniae Urinary Tract Infection
Presenter: L. Kristopher Siu
This study evaluated an OmpK36-based vaccine targeting Klebsiella pneumoniae using subcutaneous and intranasal immunization approaches in a UTI model. Eight female BALB/c mice (5 weeks old) underwent a structured schedule including primary immunization, Boost I (day 14), and Boost II (day 28), followed by sample collection and sequential challenge phases. Blood samples and weight assessments were conducted at defined intervals before and after challenges.
Subcutaneous immunization with OmpK36 (without adjuvant) increased serum IgG levels, with titres rising from baseline to approximately 8 × 10⁶ after Boost II.
Intranasal immunization showed formulation-dependent responses:
- IgG (intranasal): The rOmpK36 + PELC + CpG formulation produced the highest titres (>10⁶) compared to control and other formulations.
- IgA (intranasal): The same formulation demonstrated the strongest mucosal immune response (measured by OD450), outperforming other groups.
Overall, intranasal immunization with PELC-OmpK36 induced protective immunity against K. pneumoniae-associated UTIs.
ESCMID 2026, 17-21 April, Munich, Germany.
