CRISPR Engineering and Near-Infrared Imaging for Precision Phage Therapy Against Resistant Bacteria: Promise and Challenges
Background: Choosing and measuring treatment for resistant bacteria
A review published in Frontiers in Microbiology links phage engineering and near-infrared imaging as a precision-treatment strategy against multidrug-resistant and extensively drug-resistant bacteria. It synthesizes existing research and proposes directions for development; it should be distinguished from a study demonstrating the efficacy of a therapy combining the two technologies through new experiments.
Bacteriophages are viruses that infect bacteria. Lytic phages used for therapy multiply inside host bacteria and then cause them to burst. Enzymes produced by some phages also weaken the biofilm structure surrounding bacterial communities. However, phages that act against bacteria isolated from a patient must first be identified. Determining how much phages multiply and how active they are after reaching an infection site also remains a challenge.
Key findings: Linking gene targeting with imaging
The CRISPR–Cas approaches covered in the review include editing phage genomes and using phages as carriers for gene targeting. The latter delivers tools into bacteria to cut target DNA, targeting antibiotic-resistance genes such as blaNDM, mecA, and mcr-1. These strategies aim to kill specific bacteria or eliminate resistance to restore antibiotic susceptibility, and are distinct from phage engineering that alters host range.
Jumbo phages, whose genomes typically exceed 200 kilobases, are also reviewed. Some jumbo phages keep replicating DNA inside a protein compartment, protecting it from bacterial defense systems. When developing them as therapeutic candidates, these properties must be evaluated alongside genome safety, packaging stability, and consistency across manufacturing batches.
Near-infrared imaging is presented as a tool for measuring infection and tracking phage movement. Examples include iRFP and miRFP, near-infrared fluorescent reporters derived from bacteriophytochromes, which are bacterial photoreceptor proteins. A reporter is a protein genetically expressed to track a target of interest using a light signal. The review summarizes approaches that use these tools in experimental models to observe infection burden and phage distribution and activity over time.
Measurements validated in animals could help build models describing phage replication and clearance and generate hypotheses for studying administration strategies in humans. This does not mean that the optimization of patient-specific doses and administration timing has been established clinically.
Implications and outlook: Conditions for linking an integrated strategy to clinical evidence
The authors propose a framework connecting identification of pathogens and resistance genes, selection of suitable phages, and incorporation of response measurements into treatment design. Combination treatment with antibiotics is also a major area of consideration. Because interactions between phages and antibiotics vary with the combination and order of administration, effects observed in experiments cannot readily be generalized into a universal treatment schedule.
The human evidence summarized in the review consists mainly of compassionate use, case series, and early clinical-development experience. The review also identifies the difficulty of isolating the contribution of phages in cases where antibiotics and source control were used concurrently. Evaluating adoption in routine care requires confirmation of compatibility between patient isolates and phages, controlled clinical evaluations, and clinically meaningful endpoints.
Sterility and endotoxin control during manufacturing, along with phage neutralization by the immune system, remain challenges. Regional differences in regulatory systems complicate the development and supply of personalized products. The review proposes a development framework linking gene targeting with imaging-based measurement and emphasizes that its clinical value must be evaluated through standardized testing and quality control.
Source: Full review in Frontiers in Microbiology.
The rapid rise of multidrug-resistant and extensively drug-resistant bacterial infections has renewed interest in bacteriophages as adaptable, targeted antimicrobials. Recent advances in phage engineering, including CRISPR-based approaches, now make it possible to refine host range, strengthen lytic performance, and deliver genetic payloads that target clinically important resistance determinants such as
Developing phages against resistant bacterial infections starts with determining which phages act against bacteria isolated from a patient. For example, research on infections involving biofilms could assess candidate phages’ ability to infect bacteria and reduce biofilms, together with their interactions with antibiotics when used in combination. Animal models using near-infrared reporters provide a complementary way to examine distribution at infection sites and the duration of responses. These measurements could inform the choice of administration routes and assessment times in subsequent clinical trials. However, how well imaging signals reflect actual bacterial reduction and clinical improvement must be validated. This review alone does not establish efficacy or safety in patients.