Posters and poster guidelines

Thank you for considering to present your work as a poster at this conference.

Digital poster preparation and submission

• Page size: Prepare your poster as you would normally do for printing. You can prepare your poster in sizes A1 or A0, as the page size is not important if only presenting digitally. However, print hardcopy posters in A1 portrait format. Larger posters and those in landscape format may not be displayed due to space constraints.
• Naming your poster files: Name your poster files as follows:<your surname>-Phg25-Poster.pdf. For example, for David Jones, name your file as Jones-Phg25-Poster.pdf. DO NOT name your poster files as, e.g.,  Oxford-poster, poster2025, Oxford-phage-poster. Such files will be automatically rejected.
• Poster submission and deadlines: All poster presenters, whether attending virtually or in-person, are required to submit a digital version of their poster so that your poster is accessible to virtual attendees. Submit your final poster as PDF (<5MB) and via the link below no later than 25th August 2025 (we must have received your poster abstracts by 15th August). Late posters may not be included in the conference programme. Please DO NOT send your poster (or abstract) files by email. Please ensure you send us the very final version of your poster (as well as your poster abstract), as once published, it cannot be replaced.

Before uploading your poster, you must make sure that you follow ALL of the instructions above!

Upload your poster

Poster presentation

• Poster PDF files (required): Whether the presenter is attending virtually or in-person, poster PDF files are required, which will be made available via the secure conference documents page to the conference participants. The participants will be able to ask questions via the Zoom chatbox during the conference. There is no specific time for presenting digital posters.
• Flash-talk videos (optional, but strongly encouraged): We are pleased to offer poster presenters the opportunity to prepare a short video presentation about their poster and send it before the conference. The videos will be made available on the LPMHealthcare YouTube channel. Below is further information for sending your video presentation.
  • Download the opening slide (PhgOx25 posters first slide) and use it as the first slide of your presentation (see example: https://youtu.be/XatqenCd_IU?si=Yu1PooCD4JmSLAiz).
  • Give your presentation (no longer than 5 minutes) using Zoom or another platform of your choice.
  • Convert the video into a format compatible with YouTube (e.g., MP4).
  • Send your video to PhageOxford@gmail.com using a file transfer program, such as MailBigFile or WeTransfer.
• Hardcopy posters (optional): If attending in-person, you may bring along a printed copy of your poster (maximum A1 size) to be displayed during the conference. You may be assigned a specific day to display your poster.
• The participants can post their questions on X at any time using the meeting hashtag #PhgOx25, as well as the poster specific hashtag (given under each poster abstract) – do tag ~PhageOxford and @LPMHealthcare in your tweets.

Before uploading your poster, you must make sure that you follow ALL of the instructions above!

Upload your poster

Accepted posters

(Presenters in Bold)

Accepted poster abstracts will be displayed below. If your abstract has been accepted for presentation but it does not appear in the list below, please let us know as soon as possible by emailing PhageOxford@gmail.com.

M-13 Bacteriophage Functionalized Graphene Oxide Biosensor for the Rapid Detection of Analytes in Clinical and Environmental Sample

Hamda Y Alshehhi¹, Lina Tizani², Selvakumar Palanisamy², Habiba Alsafar^2,3, Shadi W Hasan^4,5, Ahmed F Yousef^1,2,4

¹Department of Biology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates

²Center for Biotechnology (BTC), Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates

³Department of Biomedical Engineering, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates

⁴Center for Membranes and Advanced Water Technology (CMAT), Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates

⁵Department of Chemical Engineering, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates

Rapid detection of infectious pathogens plays a critical role in public health, providing an early-warning system for identifying threats within clinical and environmental settings. Timely identification in such complex samples is essential for effective intervention and decision-making. Addressing this need, we previously developed a highly sensitive reduced graphene oxide (rGO)-based biosensor capable of detecting SARS-CoV-2 in clinical and environmental samples. In this study, we modified the biosensor to replace conventional antibodies with genetically engineered M13 bacteriophages, achieving a significant reduction in manufacturing costs and enabling in-house manufacturing to support greater manufacturing independence and quality control. The optimized biosensor maintained high sensitivity and specificity, with rapid detection in the millisecond range. Future work will focus on further engineering the biosensor to detect a broader range of pathogens and contaminants in wastewater and clinical samples, which will position the biosensor as a vital tool for public health surveillance and environmental monitoring, offering a scalable, reliable, and cost-effective solution for addressing global health challenges.

Cure of a difficult-to-treat Pseudomonas aeruginosa canine chronic otitis externa (OE) with the PYO bacteriophage cocktail followed by antibiotics

Raphaël Baudin¹, Verena Ducret², Line Gentsch³*, Karl Perron^2,4,5* and Grégory Resch¹*

*These authors contributed equally to this work.

¹Center for Research and innovation in Clinical Pharmaceutical Sciences (CRISP), Lausanne University Hospital (CHUV), Lausanne, Switzerland

²Microbiology Unit, Department of Plant Sciences, University of Geneva, 30 Quai Ernest-Ansermet, Geneva, 1211, Switzerland

³Veterinary practice Amivet Sàrl, Neuchâtel, Switzerland

⁴Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, 1 Rue Michel Servet, Geneva, 1211, Switzerland

⁵Section of Pharmaceutical Sciences, University of Geneva, 1 Rue Michel Servet, Geneva, 1211, Switzerland

A Labrador presented with severe chronic otitis externa. The ear canal was thickened and covered with foul-smelling purulent secretions, the walls showing extensive erythema with ulcerations. Pseudomonas aeruginosa was identified and standard of care (SoC, gentamycin + polymyxin) treatment had failed. Phage therapy, which uses specific bacterial viruses called bacteriophages, was proposed. PYO bacteriophage cocktail (Eliava biopreparation, Georgia) was applied locally into the ear canal after soft cleaning over three consecutive days (0.5mL per day). P. aeruginosa and phage loads were monitored from ear swabs. Antibiotic and phage susceptibility was assessed on recovered clones. Resistance mechanisms were investigated through comparative genomics. Before onset of treatment, P. aeruginosa isolates were fully susceptible to PYO in vitro. After a 2-log₁₀ P. aeruginosa load reduction by D2 post-treatment, levels returned to baseline. Interestingly, rapid and significant clinical improvement was observed, with reduced secretions and pain. We found that already at D1, the pathogen population changed with the emergence of phage-resistant clones, without modification of antibiograms. These clones harboured large genomic deletions or mutations impacting genes involved in O-antigen and type IV pilus biosynthesis known as phage receptors. Still, phages persisted in the ear canal for three weeks, with evidence of phage-susceptible P. aeruginosa at D65. Finally, instillations of SoC at D65 and D90 cleared the infection after >2 years of ineffectiveness. Phage therapy alone significantly improved clinical symptoms and modified the P. aeruginosa ear community towards mixed-resistance profiles. Although antibiograms remained similar, we believe that this pathogen community switch could explain the observed successful therapeutic outcome. Decrease in virulence or capacity to form biofilm of the selected phage-resistant clones might be involved and are currently investigated.

Establishing a phage collection as a first step towards a new strategy for the management of non-typhoidal Salmonellosis (NTS)

Raphaël Baudin¹, Wolf-Dietrich Hardt², Roger Stefan³ and Grégory Resch¹

¹Center for Research and innovation in Clinical Pharmaceutical Sciences (CRISP), Lausanne University Hospital (CHUV), Lausanne, Switzerland

²Institute of microbiology, ETH Zürich, Zürich, Switzerland

³National Reference Centre for Enteropathogenic Bacteria and Listeria (NENT), University of Zürich (UZH), Zürich, Switzerland

Acute non-typhoidal salmonellosis is the second most common cause of gastroenteritis in Switzerland. Antibiotics are not recommended due to limited efficacy and the perturbation they cause to the gut microbiota, a natural barrier to the infection. Thus, untreated carriers represent an important reservoir for transmission to vulnerable people, in whom the infection can become life-threatening. Using bacteriophages, specific bacterial viruses, is proposed as a decolonization strategy for carriers. A collection of Salmonella clinical isolates was assembled in collaboration with NENT, UZH. Bacteriophages were isolated from local wastewaters. Their host ranges were characterized through efficiency of plating (EOP) assays. In silico analyses of the phage genomes allowed evaluation of their suitability for clinical intervention. We retrieved eight genetically distinct lytic phages. None carried genes coding for known virulence or antimicrobial resistance determinants. The collection efficiently infected and lysed 99% of 104 Salmonella clinical isolates from the six most dominant serovars (Enteritidis, Typhimurium, Monophasic Typhimurium, Napoli, Infantis, and Derby). However, S. Infantis and S. Derby displayed high resistance to individual phages, suggesting presence of specific and highly effective anti-phage mechanisms in these serovars. First phage training experiments suggested possibility to increase virulence of some phages. Genetically different Salmonella phages with clinical potential were isolated from Swiss wastewaters. These phages cover a broad spectrum of dominant serovars, S. Infantis and S. Derby being the exceptions. Next steps towards clinical application are i) to evaluate their in vitro efficacy, ii) to produce few promising candidates through the Swissmedic authorized CHUV phage manufacturing pipeline and to iii) evaluate their efficacy in vivo in a preclinical model of Salmonella infection.

How Cellular Resources Limit T7 Bacteriophages Growth

Liqi Chen, Aidan T Brown

School of Physics and Astronomy, King’s Buildings, EH9 3FD, University of Edinburgh, Edinburgh, UK

Efficient resource allocation is crucial for cellular growth and survival, particularly under constrained conditions. A well-established “growth law” shows a linear correlation between bacterial growth rates and the cellular concentration of ribosomes, the machines that make proteins. Ribosomes can be inactivated by the ribosome-targeted antibiotic chloramphenicol, leaving only a fraction capable of translating proteins, referred to as active ribosomes. Our study extends a growth principle to bacteriophages T7, showing that T7 replication rates are directly proportional to the number of active ribosomes per cell under ribosome-limited conditions. Under the specific conditions, this findings suggest that ribosome availability can be a key limiting factor for bacteriophages growth.

Host phase variation mediates the persistent co-existence of lytic bacteriophages with gut Bacteroidales

Adrián Cortés-Martín^1,2, Colin Buttimer¹, Jessie L Maier³, Ciara A Tobin¹, Lorraine A Draper¹, R Paul Ross¹, Manuel Kleiner³, Colin Hill¹, Andrey N Shkoporov¹

¹APC Microbiome Ireland & School of Microbiology, University College Cork, Cork, T12 YT20, Ireland

²Sport and Health University Research Institute (iMUDS), University of Granada, Granada, Spain

³Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America

Bacteriophages (phages) in the gut microbiome persist in long-term stable coexistence with their bacterial hosts driven by dynamic eco-evolutionary interactions. CrAss-like phages represent the most abundant group of bacteriophages in the human gut. They infect members of the order Bacteroidales and, despite their virulent nature, they can effectively co-exist with their host bacteria without dramatically impacting community structure or target bacterial numbers. In this study, we investigated the mechanisms underlying phage-bacteria co-existence through an in vitro multi-omics approach (transcriptomics, proteomics and metabolomics). We examined four phage-bacteria pairs: three Bacteroides strains paired with three crAss-like phages (Bacteroides intestinalis and фcrAss001, Bacteroides xylanisolvens and фcrAss002, and an acapsular mutant of Bacteroides thetaiotaomicron with DAC15), and Parabacteroides distasonis APCS2/PD with the siphovirus фPDS1. Our findings reveal that phase variation of individual capsular polysaccharides (CPSs) is the primary mechanism that promotes phage co-existence in Bacteroidales, but this is not the only strategy. Alternative resistance mechanisms, which also involve phase variation but less efficiently than changes in CPS expression, can be activated to enhance bacterial survival by regulating gene expression and resulting in metabolic adaptations, particularly in amino acid degradation pathways. In the absence of CPS, higher transcriptomic, proteomic, and metabolomic changes are observed since more factors are involved in achieving the equilibrium between bacterial and host populations. These mechanisms allow bacterial populations to survive in the presence of phages, and vice versa. These results advance our understanding of long-term phage-host interaction, offering insights into the long-term persistence of crAss-like phages and extending these observations to other phages, such as фPDS1.

Development of Novel Drug Discovery Approaches Based on Bacteriophage Technology

Longzhu Cui

Division of Bacteriology, School of Medicine, Jichi Medical University, Japan

Bacteriophages have gained attention not only for their antibacterial properties but also as a novel modality for drug discovery, with applications in cancer treatment, vaccine development, and gene therapy. We have developed a phage-based approach for sequence-specific bacterial elimination, targeting drug-resistant bacteria. By engineering non-replicative phages and incorporating specific genes, we have enhanced phage safety, targeting, and stability. Our research focuses on generating phage-based drugs and optimizing gene incorporation techniques for therapeutic applications. To counteract resistance mechanisms, we are designing phages that provide a targeted alternative to conventional antibiotics. For biofilm-forming bacteria, we are developing phages with improved biofilm-disruption capabilities to address persistent infections. Additionally, we are investigating synthetic phages capable of accessing and controlling intracellular bacteria, offering potential solutions for hard-to-treat infections. Beyond antibacterial applications, we are advancing phage-based vaccine development by utilizing phages as delivery vehicles for immunogenic components. Furthermore, we have established a tumor-targeting phage drug delivery system (DDS) that integrates controlled drug release mechanisms responsive to the tumor microenvironment, enabling precise and selective cancer treatment. Through these strategies, we aim to establish phages as a versatile platform for combating refractory bacterial infections and developing innovative therapeutic applications.

Exploring Nanomotion Technology for Phage Therapy: A Novel Diagnostic Tool to Combat Antimicrobial Resistance

Anthony Vocat¹, Amanda Luraschi-Eggemann², Grzegorz Jóźwiak², Julia Dolezel³, Zahra Azizi3, Shreyas Vasantham³, Salomé Gutiérrez³, Danuta Cichocka², Alexander Sturm², Gregory Resch¹

¹Centre for Research and Innovation in Clinical Pharmaceutical Sciences (CRISP), Lausanne University Hospital (CHUV), Lausanne, Switzerland

²Resistell AG, Muttenz, Switzerland

³Cellectric Biosciences GmbH, Vienna, Austria

Antimicrobial resistance (AMR) is an escalating global health threat, responsible for hundreds of thousands of deaths annually, with projections reaching 10 million fatalities per year by 2050 without effective interventions. Phage therapy, utilizing bacteriophages to target drug-resistant bacteria, presents a promising complementary approach to antibiotic treatments. This study explores the application of nanomotion technology for rapid, growth-independent in vitro phage susceptibility testing (PST). We developed Phenotech PST, an innovative technology that simplifies empirical drop test assays (DTA) by measuring the real-time nanomotions (vibrations) of living bacterial cells. These vibrations are detected via micromechanical sensors (cantilevers). Clinical isolates of Pseudomonas aeruginosa (n=47) were exposed to five distinct bacteriophages across 171 experiments. Machine learning algorithms were applied to analyze the resulting nanomotion data. Additionally, PST was performed directly on patient sputum samples, circumventing traditional bacterial isolation steps. Phenotech PST significantly reduced the time-to-result (TTR) from approximately 16 hours for standard DTA to just 6 hours. By analyzing variance slopes of nanomotion signals, the technology accurately classified phage activity, correlating with observed lysis patterns in DTA. While no significant signal differences were found between inactive phages and control samples (p > 0.99), Phenotech PST achieved 91% accuracy in distinguishing clear and turbid lysis outcomes, with 97.5% sensitivity and 83% specificity (p < 0.001). Preliminary sputum testing results were promising, though further optimization is needed for standardization. Nanomotion technology demonstrates significant potential for enhancing PST and guiding phage therapy decisions. By providing a rapid, reliable, and growth-independent readout, this method addresses key limitations of traditional assays. Future work will focus on refining sputum testing protocols, incorporating temperature-controlled conditions at 37°C, and optimizing TTR. Our findings contribute to the advancement of phage-based diagnostics, offering a valuable tool for combating AMR.

Bacteriophage-Based Therapeutic Strategies Against Mycobacterium tuberculosis and Nontuberculous Mycobacteria: Advances Toward Clinical Application

Anthony Vocat¹, Saskia Janssen², Graham F. Hatfull³, Andreas H. Diacon², Gregory Resch^1 1 Centre for Research and Innovation in Clinical Pharmaceutical Sciences (CRISP), Lausanne University Hospital (CHUV), Lausanne, Switzerland. ²TASK, Cape Town, South Africa. ³Department of Biological Sciences, University of Pittsburgh, Pittsburgh, USA Abstract: Tuberculosis (TB) and infections caused by nontuberculous mycobacteria (NTM) remain major global health challenges, particularly with the rise of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains. Bacteriophage therapy is emerging as a promising adjunct or alternative to conventional treatments. Recent clinical cases and experimental studies support its potential efficacy, warranting further investigation. To explore phage-based strategies, Mycobacterium smegmatis was employed as a non-pathogenic model organism. Three well-characterized recombinant mycobacteriophages, previously shown to be active against M. smegmatis and M. tuberculosis, were utilized. Large-scale production and purification protocols were developed to meet Good Manufacturing Practice (GMP) standards, with approval from Swissmedic for clinical-grade phage preparations. In parallel, environmental sampling and soil extract processing enabled the isolation and full characterization (morphological, genomic, and host range profiling) of five novel mycobacteriophages. We successfully established large-scale GMP-compliant production of therapeutic phages, a critical step toward clinical application. Five new phages active against M. smegmatis were isolated and fully characterized, expanding the available therapeutic arsenal. Preliminary in vitro studies indicate potential synergistic effects when these phages are combined with standard anti-TB and anti-NTM antibiotics. Further testing is ongoing against a panel of clinical M. tuberculosis and NTM isolates, including MDR and XDR strains. Our findings support the feasibility and therapeutic promise of bacteriophage applications in the treatment of TB and NTM infections. The successful development of GMP-grade phages and discovery of novel candidates lay the groundwork for upcoming clinical trials. Future work will focus on assessing efficacy in MDR/XDR M. tuberculosis infections, with the goal of integrating phage therapy into standard care protocols.

Genomic diversity and genetic exchange between prophages of Burkholderia pseudomallei, B. thailandensis and their free phages from soils

Patoo Withatanung¹, Veerachat Muangsombut¹, Sujintana Janesomboon¹, Vanaporn Wuthiekanun², Premjit Amornchai², Sorujsiri Chareonsudjai³, Dave J. Baker⁴, Martha R.J. Clokie⁵, Edouard E. Galyov⁵, Ozan Gundogdu⁶, Sunee Korbsrisate¹

¹Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand

²Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand

³Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand

⁴Science Operations, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK

⁵Becky Mayer Centre for Bacteriophage Research, Department of Genetics, Genomics and Cancer Sciences, University of Leicester, Leicester, UK

⁶Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK

Burkholderia pseudomallei, pathogenic bacterium that causes melioidosis, can be found coexisting with Burkholderia thailandensis and B. thailandensis capsule variant (BTCV) in the environment. Currently, most Burkholderia phage studies focus on in silico analyzes of clinical strains which are likely to reflect only a small subset of total diversity. This study aimed to investigate the genomes of induced prophages and soil-isolated free phages associated with Burkholderia spp. To achieve this, soil-isolated B. pseudomallei, B. thailandensis, and BTCV were induced with mitomycin C; resulting in the recovery of 66 culturable prophages. In addition, 16 phages were isolated from soil. Genomic analysis of these 82 Burkholderia-associated phages revealed a dynamic interplay between lysogenic and lytic phage lifestyles in the environment. The sequence homology and integrases presence in environmental free phages support the idea that they originate from prophages through environmental triggers. Three B. pseudomallei phage clades were identified: BP1 represents a novel group whereas clades BP2-3 showed homology with known B. pseudomallei phages. The finding that clades BP2 and BP3 share sequence similarity with phages isolated from melioidosis patients indicates that prophages can be induced and detected in patients. B. thailandensis and BTCV phages form seven clades (BT1-7), each clade contains various genes that promote bacterial survival, stress resistance and evolution. This pioneering study provides novel insights into Burkholderia phage dynamics, origins and their potential for horizontal transfer between environmental and clinical settings. Detection of B. pseudomallei phages in the environment has the potential to serve as ecological markers for B. pseudomallei surveillance.

Rational in vitro design of a two-phage cocktail against a contemporary A. baumannii strain recovered from a burned patient at CHUV

Hugues de Villiers de la Noue, Gwenaëlle Golliard, Xavier Vuattoux, Gregory Resch

Laboratory of Bacteriophages and Phage Therapy, Center for Research and Innovation in Clinical Pharmaceutical Sciences (CRISP), Lausanne University Hospital (CHUV), Switzerland

Acinetobacter baumannii is a major threat to human health. With the spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains, development of complementary strategies is needed. A complimentary strategy could be phage therapy, which uses bacteriophages (phages), i.e viruses that kill bacterial cells during their life cycle. We designed a two-phage cocktail highly efficient against an XDR A. baumannii isolate collected from a patient with burn wound infection at CHUV (termed Ab125). A first in vitro screen of our collection of 36 different phages identified only phage vB_AbaM_3098 as capable of lysing Ab125. However, quick (ca. 6 h) selection of phage-resistant clones (termed Ab139) occurred. Very interestingly, we observed that Ab139 became susceptible to six different phages in the collection, otherwise inactive on Ab125. Phage-resistance was also selected when Ab139 was challenged with either of the six phages, with bacterial regrowth observed between 12 h and 16 h. However, combination of vB_AbaM_3098 and phage vB_AbaM_3014 led to a clinically usable two-phage cocktail capable of totally inhibiting the growth of Ab125. Treatment with the phage cocktail led to 86.67% survival after 5 days in the in vivo Galleria Mellonella model of infectious diseases, compared to 0% in the non-treated group. Finally, the therapeutic potential of the assembled cocktail was tested in synergy with Standard-of-Care (SOC) antibiotics by both synograms and Time-kill assays, and a synergy with colistin was detected. We show that the combination of a phage that only slightly shifted the in vitro bacterial growth curve with an “inactive phage” led to the formulation of a highly bactericidal phage cocktail against an XDR A. baumannii clinical isolate. This work highlights the complexity sometimes involved in the assembly of potent phage cocktail, as well as their potential in difficult-to treat infections in combination with SOC antibiotics.

Optical trapping of bacteria for ultrafast bacteriophage lysis detection at the single-cell level

Hugues de Villiers de la Noue¹, Nicolas Villa², Enrico Tartari², Simon Glicenstein³, Emmanuel Picard³, Emmanuel Hadji³, Pierre R. Marcoux⁴, Marc Zelsmann⁵, Romuald Houdré² and Gregory Resch¹

¹Laboratory of Bacteriophages and Phage Therapy, Center for Research and Innovation in Clinical Pharmaceutical Sciences (CRISP), Lausanne University Hospital (CHUV), Switzerland

²Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland

³University Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, SiNaPS, France

⁴University Grenoble Alpes, CEA, LETI, Minatec-Campus, France

⁵University Grenoble Alpes, CNRS, CEA/LETI Minatec, Grenoble INP, LTM, France

Regarding their high bacterial strain specificity, rapid and accurate selection of therapeutic bacteriophages is crucial in phage therapy clinical protocols. Here, we report the use of photonic crystal cavities as on-chip optical nanotweezers for ultrafast phage susceptibility testing (PST) at the single bacterium level. On a silicon photonic chip, resonant photonic crystal cavities allow the trapping of a single Escherichia coli B cell and sensing its stressed-induced modifications. This is achieved by monitoring the transmitted optical power through the photonic chip that carries information about the bacterium’s characteristics. E. coli cells were put in contact with T4 Myoviridae and T1 Tunaviridae phages before being injected in the trapping device. We report direct observation of a bacterium-phage lytic event in the optical cavity. The cell’s morphological changes caused by the phage activity prior and after lysis are detected via the transmitted power as well through a microscope imaging system. The lytic event leads to a sudden refractive index reduction, which is attested by an abrupt drop in transmission and a reduced imaging contrast of the cell. Accordingly, only 40min ± 5min after mixing phages and bacteria (t = 0), we observe an abrupt decrease in transmission signal correlating with the bursts of the trapped bacterium. Interestingly, we observe different drop in transmission depending on the phages used to lyse the bacterial cell, correlated with the estimated burst size of the phages. This detection of the lysis event is much faster than current culture-based phagograms usually requiring 16h-24h incubation times. This innovative phagogram approach paves the way to ultrafast PST at the single bacterium level.