The Congress of the European Society of Clinical Microbiology and Infectious Diseases – known as ESCMID Global – brings together leading experts in infectious diseases and clinical microbiology to exchange ideas and explore the latest innovations and cutting-edge research. Here, Gerry Hughes reports on some of the key themes and highlights from the recent 2025 gathering.
The escalating global threat of antimicrobial resistance (AMR) demands evidence-informed, multidisciplinary action. In 2021, an estimated 4.71 million deaths were associated with bacterial AMR, with 8.22 million associated deaths projected by 2050, according to the latest global burden of bacterial resistance analysis published in The Lancet.
At ESCMID Global 2025 in Vienna, Austria (11-15 April), leading clinicians, researchers and policymakers gathered to address this crisis and share essential considerations for healthcare professionals.
Key themes included the intersection of infectious and chronic diseases, intravenous (IV) verses per os (PO) antimicrobial prescribing, and treating multidrug-resistant Gram-negative infections. Each of these is underpinned by evolving antimicrobial stewardship practices and optimising patient care and outcomes.
The intersection of infectious and chronic diseases
The emerging association between diabetes and AMR is an increasing cause for concern, according to Professor Reinout van Crevel, professor in global health and infectious diseases at Radboud University Medical Centre in Nijmegen, Netherlands. Indeed, evidence suggests patients with diabetes are more likely to develop resistant infections.
During his ESCMID Global session, Professor van Crevel highlighted the increased risk and severity of infections such as rhinocerebral mucormycosis, Fournier’s gangrene, malignant external otitis and invasive Klebsiella pneumoniae in patients with diabetes. These conditions often carry worse outcomes, and longer hospital stays compared with non-diabetic populations, he said.
Infection-related risks are particularly heightened in patients with type 1 diabetes, possibly due to greater glycaemic variability. Immunosuppression and microbial dysbiosis were cited as key contributors to this vulnerability. The session reinforced the need for integrated infection management strategies and tighter glycaemic control, especially around surgery or antimicrobial use in patients with diabetes.
‘Expect the unexpected’ was Professor Jörg Janne Vehreschild’s central message regarding infection risks in patients prescribed novel oncological agents – particularly those ending in –cel, –cept, –clib, –inib, –sib, or –mab. These therapies may alter immune function and infection profiles, necessitating bespoke infection prophylaxis strategies.
Professor Vehreschild noted key infection prophylaxis considerations, including for the herpes zoster virus, hepatitis B and C, and pneumocystis jirovecii pneumonia, as well as neutropenic bacterial prophylaxis.
He also reminded delegates that resistant organisms often emerge due to selective pressure from infection treatment itself. ‘When we start treating with antibiotics, we can turn our patient into a petri dish,’ he said, further highlighting the need for good stewardship in this area of practice.
Evidence-based antimicrobial prescribing: IV and PO myths vs data
The session from Dr Brad Spellberg, chief medical officer at Los Angeles County–University of Southern California Medical Center in the US, delivered a robust challenge to entrenched beliefs around intravenous (IV) antibiotic use. He focused particularly on conditions historically viewed as requiring prolonged parenteral therapy – namely osteomyelitis, bacteraemia and endocarditis. And his message was clear: the clinical default to IV therapy in these cases is not supported by evidence, but by inertia.
‘Not a single controlled study has ever demonstrated that IV therapy is superior to oral for these three diseases,’ said Dr Spellberg. He framed this as a battle between evidence-based medicine and the influence of expert consensus, noting that many clinicians resist oral therapy due to the misconception that existing randomised controlled trials (RCTs) ‘don’t apply to my patient’.
He traced the historical basis for prolonged IV therapy in osteomyelitis to an uncontrolled 1970 case series from a time when oral alternatives weren’t available. Since then, he notes that numerous observational studies and 10 RCTs have shown no clinically significant difference between oral and IV therapy.
A 2022 meta-analysis led by Dr Spellberg demonstrated that overall treatment success between oral and IV therapy was not significantly different.
For bacteraemia, 11 RCTs involving 1,012 patients demonstrated non-inferiority of oral treatment. Dr Spellberg and his team concluded that the confidence interval actually favoured oral therapy in terms of treatment success.
These findings challenge the deeply held assumption that bloodstream infections require prolonged IV regimens by default.
The same applied to infective endocarditis (IE). Early evidence supporting IV therapy stems from 1940s studies on IV penicillin in an era without oral comparators. However, more recent data tell a different story.
In a 2020 narrative review, Dr Spellberg advocated for oral step-down therapy in IE after initial IV treatment once bacteraemia is cleared and the patient is clinically stable. His 2022 meta-analysis even found oral therapy to be statistically superior in treatment success for IE.
To counter clinical inertia, he proposed five criteria for switching from IV to oral therapy:
- Patient is clinically stable
- Source control is achieved
- The oral regimen has known efficacy for the causative pathogen
- The patient has no gastrointestinal absorption issues
- No psychosocial or adherence-related barriers to oral therapy.
Clinical updates and challenges in multidrug-resistant infections
A comprehensive update on the expanding role of beta-lactam/beta-lactamase inhibitor (BL/BLI) combinations in treating multidrug-resistant Gram-negative infections was provided by Professor Laurent Dortet, professor in the department of microbiology at Bicetre Hospital in Paris, France.
At his ESCMID event he discussed recent evidence on the rationale for the use of new BL/BLI combinations and in critically ill patients. Newer BLIs such as relebactam and vaborbactam have a better activity against difficult to treat Gram-negative infections compared to older agents such as clavulanic acid or tazobactam, he said.
Yet, Professor Dortet cautioned that their uptake in clinical practice remains limited due to cost, regional regulatory discrepancies and the lack of large-scale real-world efficacy data.
He stressed the need for post-marketing studies with narrower non-inferiority margins and robust clinical endpoints to determine their optimal use.
Dr Carolina Garcia-Vidal, infectious diseases consultant at Hospital Clinic Barcelona, Spain, expanded on this Bl/BLI evidence by addressing the unintended consequences of empirical carbapenem use in haematology patients.
Referencing the European Conference on Infections in Leukaemia’s 10 recommendations – known as ECIL-10 – she highlighted appropriate clinical scenarios for empirical use of newer BL/BLI agents.
She also raised concerns about collateral effects – specifically, the tendency of carbapenems to eradicate beneficial anaerobic gut flora. This disruption has been linked to poorer outcomes in critically ill and immunocompromised patients.
Among patients with complicated urinary tract infections or pyelonephritis, Dr Garcia-Vidal discussed how cefepime/enmetazobactam has outperformed piperacillin/tazobactam in clinical cure and microbiological eradication in clinical trial data.
Dr Garcia-Vidal ended her ESCMID session by calling for greater inclusion of these microbiome considerations in clinical guidelines. She highlighted Spanish national guidance as an example of forward-thinking policy that integrates antimicrobial impact on the gut flora into decision-making frameworks.
Conclusion
ESCMID Global 2025 delivered a compelling call to action: use evidence to shape clinical care. From diabetes and cancer to administration options and drug-resistant pathogens, the sessions reinforced the need for agile, data-informed, multidisciplinary approaches.
For secondary healthcare professionals, adapting to new evidence is key to both individual patient care and public health. Translating scientific rigour into practice is no longer optional: it is a clinical imperative.
