Tony Hong Wei Chang

All Publications

• New Pseudomonas infections drive Pf phage transmission in CF airways. JCI insight Pourtois, J. D., Haddock, N. L., Gupta, A., Khosravi, A., Martinez, H. A., Schmidt, A. K., Prakash, P. S., Jain, R., Fleming, P., Chang, T. H., Milla, C., Secor, P. R., De Leo, G. A., Bollyky, P. L., Burgener, E. B. 2025

  Abstract

  Pf bacteriophages, lysogenic viruses that infect Pseudomonas aeruginosa (Pa), are implicated in the pathogenesis of chronic Pa infections; phage-infected (Pf+) strains are known to predominate in people with cystic fibrosis (pwCF) who are older and have more severe disease. However, the transmission patterns of Pf underlying the progressive dominance of Pf+ strains are unclear. In particular, it is unknown whether phage transmission commonly occurs horizontally between bacteria via viral particles within the airway or if Pf+ bacteria are mostly acquired via de novo Pseudomonas infections. Here, we studied Pa genomic sequences from 3 patient cohorts totaling 662 clinical isolates from 105 pwCF. We identified Pf+ isolates and analyzed transmission patterns of Pf within patients between genetically similar groups of bacteria called "clone types". We found that Pf was predominantly passed down vertically within Pa clone types and rarely via horizontal transfer between clone types within the airway. Conversely, we found extensive evidence of Pa de novo infection by a new, genetically distinct Pf+ Pa. Finally, we observed that clinical isolates showed reduced activity of the type IV pilus and reduced susceptibility to Pf in vitro. These results cast new light on the transmission of virulence-associated phages in the clinical setting.

  View details for DOI 10.1172/jci.insight.188146

  View details for PubMedID 40261708

• Prophages are infrequently associated with antibiotic resistance in Pseudomonas aeruginosa clinical isolates. mSphere Chang, T. H., Pourtois, J. D., Haddock, N. L., Furukawa, D., Kelly, K. E., Amanatullah, D. F., Burgener, E., Milla, C., Banaei, N., Bollyky, P. L. 2025: e0090424

  Abstract

  Lysogenic bacteriophages can integrate their genome into the bacterial chromosome in the form of a prophage and can promote genetic transfer between bacterial strains in vitro. However, the contribution of lysogenic bacteriophages to the incidence of antimicrobial resistance (AMR) in clinical settings is poorly understood. Here, in a set of 186 clinical isolates of Pseudomonas aeruginosa collected from respiratory cultures from 82 patients with cystic fibrosis, we evaluate the links between prophage counts and both genomic and phenotypic resistance to six anti-pseudomonal antibiotics: tobramycin, colistin, ciprofloxacin, meropenem, aztreonam, and piperacillin-tazobactam. We identified 239 different prophages in total. We find that P. aeruginosa isolates contain on average 3.06 ± 1.84 (SD) predicted prophages. We find no significant association between the number of prophages per isolate and the minimum inhibitory concentration for any of these antibiotics. We then investigate the relationship between particular prophages and AMR. We identify a single lysogenic phage associated with phenotypic resistance to the antibiotic tobramycin and, consistent with this association, we observe that AMR genes associated with resistance to tobramycin are more likely to be found when this prophage is present. However, we find that they are not encoded directly on prophage sequences. Additionally, we identify a single prophage statistically associated with ciprofloxacin resistance but do not identify any genes associated with ciprofloxacin phenotypic resistance. These findings suggest that prophages are only infrequently associated with the AMR genes in clinical isolates of P. aeruginosa.IMPORTANCEAntibiotic-resistant infections of Pseudomonas aeruginosa (Pa), a leading pathogen in patients with cystic fibrosis (CF), are a global health threat. While lysogenic bacteriophages are known to facilitate horizontal gene transfer, their role in promoting antibiotic resistance in clinical settings remains poorly understood. In our analysis of 186 clinical isolates of P. aeruginosa from CF patients, we find that prophage abundance does not predict phenotypic resistance to key antibiotics but that specific prophages are infrequently associated with tobramycin resistance genes. In addition, we do not find antimicrobial resistance (AMR) genes encoded directly on prophages. These results highlight that while phages can be associated with AMR, phage-mediated AMR transfer may be rare in clinical isolates and difficult to identify. This work is important for future efforts on mitigating AMR in CFCF and other vulnerable populations affected by Pa infections and advances our understanding of bacterial-phage dynamics in clinical infections.

  View details for DOI 10.1128/msphere.00904-24

  View details for PubMedID 39945525

• Pseudomonas superinfection drives Pf phage transmission within airway infections in patients with cystic fibrosis. bioRxiv : the preprint server for biology Pourtois, J. D., Haddock, N. L., Gupta, A., Khosravi, A., Martinez, H., Schmidt, A. K., Prakash, P. S., Jain, R., Fleming, P., Chang, T. H., Milla, C., Secor, P. R., De Leo, G. A., Bollyky, P. L., Burgener, E. B. 2025

  Abstract

  Pf bacteriophages, lysogenic viruses that infect Pseudomonas aeruginosa (Pa), are implicated in the pathogenesis of chronic Pa infections; phage-infected (Pf+) strains are known to predominate in people with cystic fibrosis (pwCF) who are older and have more severe disease. However, the transmission patterns of Pf underlying the progressive dominance of Pf+ strains are unclear. In particular, it is unknown whether phage transmission commonly occurs horizontally between bacteria within the airway via viral particles or if Pf+ bacteria are mostly acquired via new Pseudomonas infections. Here, we have studied Pa genomic sequences from 3 patient cohorts totaling 663 clinical isolates from 105 pwCF. We identify Pf+ isolates and analyze transmission patterns of Pf within patients between genetically similar groups of bacteria called "clone types". We find that Pf is predominantly passed down vertically within Pa lineages and rarely via horizontal transfer between clone types within the airway. Conversely, we find extensive evidence of Pa superinfection by a new, genetically distinct Pa that is Pf+. Finally, we find that clinical isolates show reduced activity of the type IV pilus and reduced susceptibility to Pf in vitro. These results cast new light on the transmission of virulence-associated phages in the clinical setting.

  View details for DOI 10.1101/2025.01.14.632786

  View details for PubMedID 39868244

  View details for PubMedCentralID PMC11761399

• Bacteriophage therapy for multidrug-resistant infections: current technologies and therapeutic approaches The Journal of Clinical Investigation Kim, M., Suh, G. A., Cullen, G. D., Rodriguez, S. P., Dharmaraj, T., Chang, T. H., Li, Z., Chen, Q., Green, S. I., Lavigne, R., Pirnay, J., Bollyky, P. L., Sacher, J. C. 2025

  View details for DOI 10.1172/JCI187996

• Feasibility and Methodology of a Pilot Free Blood Pressure Monitoring and Follow-Up Program at Two Free Clinics. Journal of primary care & community health Mikos, G., Yu, B., Balbin, J., Martinez-Reyes, L., Tang, J. M., Lieu, B. N., Tran, E., Xue, A., Lee, J., Wary, N., Franke, C., Panyanouvong, N., Chaclan, M. J., Chang, T. H., Chen, C., Guo, M. Y., Harvell, K., Horan, R., Johnson, N. A., Kim, A., Liu, E., Liu, L., Nuñez-Perez, P., Quig, M., Sanyal, A., Sharma, K., Wang, I., Wang, K., Filsoof, A., Charon, M., Montacute, T., Singh, B. 2024; 15: 21501319241278836

  Abstract

  Hypertension affects approximately 1 in 2 adults in the US. Home blood pressure (BP) monitoring programs are effective in the diagnosis and management of hypertension. Free clinics serve as an integral safety net for millions of uninsured and economically disadvantaged patients in the US. The feasibility and effects of a free home BP monitoring and follow-up program in a free clinic setting is not well characterized.This was a prospective study of the implementation of a pilot BP monitoring and follow-up program between March 2021 and August 2023 at 2 free clinics in the San Francisco Bay Area. A total of 78 hypertensive patients were enrolled in the program and given a free BP monitor. We surveyed via telephone the change in systolic and diastolic BPs and BP monitor use and comfort at 3 weeks. Volunteers in clinic roles involved in the BP monitoring program were surveyed to assess their time spent and perceptions of the program.Of the 78 patients, 37 provided responses to the 3-week survey. A total of 36 of 37 (97%) patients reported using their BP monitor. A total of 35 patients reported using it at least once a week (95%), with the majority reporting at least four uses a week (68%). A total of 36 patients (97%) planned on continuing to use their BP monitor. At 3 weeks, the mean systolic and diastolic BP changed by -6.40 mmHg (95% CI, -10.8 to -2.01 mmHg; P = .00577) and -2.72 mmHg (95% CI, -5.62 to 0.188 mmHg; P = .0657), respectively. The time commitment for this program ranged from 130 ± 51 min for program leaders to 16 ± 14 min per week for patient-facing roles. All volunteer roles (patient-facing, phone follow-up, program leaders) expressed that they had a clear understanding of their responsibilities in the program (median 4 on Likert scale, IQR 3-5).Home BP monitoring and follow-up is feasible to implement in free clinics, resulting in high rates of patient engagement among respondents. Our findings suggest that home BP monitoring and follow-up programs may be beneficial in vulnerable patient populations.

  View details for DOI 10.1177/21501319241278836

  View details for PubMedID 39269685

• Pf bacteriophages hinder sputum antibiotic diffusion via electrostatic binding. Science advances Chen, Q., Cai, P., Chang, T. H., Burgener, E., Kratochvil, M. J., Gupta, A., Hargill, A., Secor, P. R., Nielsen, J. E., Barron, A. E., Milla, C., Heilshorn, S. C., Spakowitz, A., Bollyky, P. L. 2024; 10 (22): eadl5576

  Abstract

  Despite great progress in the field, chronic Pseudomonas aeruginosa (Pa) infections remain a major cause of mortality in patients with cystic fibrosis (pwCF), necessitating treatment with antibiotics. Pf is a filamentous bacteriophage produced by Pa and acts as a structural element in Pa biofilms. Pf presence has been associated with antibiotic resistance and poor outcomes in pwCF, although the underlying mechanisms are unclear. We have investigated how Pf and sputum biopolymers impede antibiotic diffusion using pwCF sputum and fluorescent recovery after photobleaching. We demonstrate that tobramycin interacts with Pf and sputum polymers through electrostatic interactions. We also developed a set of mathematical models to analyze the complex observations. Our analysis suggests that Pf in sputum reduces the diffusion of charged antibiotics due to a greater binding constant associated with organized liquid crystalline structures formed between Pf and sputum polymers. This study provides insights into antibiotic tolerance mechanisms in chronic Pa infections and may offer potential strategies for novel therapeutic approaches.

  View details for DOI 10.1126/sciadv.adl5576

  View details for PubMedID 38820163

  View details for PubMedCentralID PMC11141622

• Hydrogels for Local and Sustained Delivery of Bacteriophages to Treat Multidrug-Resistant Wound Infections. bioRxiv : the preprint server for biology Lin, Y. H., Dharmaraj, T., Chen, Q., Echterhof, A., Manasherob, R., Zheng, L. J., de Leeuw, C., Peterson, N. A., Stannard, W., Li, Z., Hajfathalian, M., Hargil, A., Martinez, H. A., Chang, T. H., Blankenberg, F. B., Amanatullah, D., Chaudhuri, O., Bollyky, P. 2024

  Abstract

  Bacteriophages (phages), viruses that specifically target and kill bacteria, represent a promising strategy to combat multidrug-resistant (MDR) pathogens such as Pseudomonas aeruginosa (Pa). However, delivering sufficient concentrations of active phages directly to the infection site remains challenging, with current methods having variable success. Here we present "HydroPhage", an innovative hydrogel system for the sustained release of high-titer phages to effectively treat infections caused by MDR pathogens. Our injectable hydrogels, featuring dual-crosslinking of hyaluronic acid and PEG-based hydrogels through static covalent thioether bonds and dynamic covalent hemithioacetal crosslinks (DCC), encapsulate phages at concentration up to 1011 PFU/mL, and achieves controlled release of 109 PFU daily over a week, surpassing levels of current clinical dosages, with more than 60% total phage recovery. In a preclinical mouse model of extended wound infection, compared to intravenous treatment, we demonstrate enhanced bacterial clearance by localized, high-dose, and repeated phage dosing despite the emergence of bacterial resistance to phages. This work advances the development of clinically practical wound dressings tailored for resistant infections.

  View details for DOI 10.1101/2024.05.07.593005

  View details for PubMedID 38766200

  View details for PubMedCentralID PMC11100690

• Pf bacteriophages hinder sputum antibiotic diffusion via electrostatic binding. bioRxiv : the preprint server for biology Chen, Q., Cai, P., Chang, T. H., Burgener, E., Kratochvil, M. J., Gupta, A., Hargil, A., Secor, P. R., Nielsen, J. E., Barron, A. E., Milla, C., Heilshorn, S. C., Spakowitz, A., Bollyky, P. L. 2024

  Abstract

  Despite great progress in the field, chronic Pseudomonas aeruginosa (Pa) infections remain a major cause of morbidity and mortality in patients with cystic fibrosis, necessitating treatment with inhaled antibiotics. Pf phage is a filamentous bacteriophage produced by Pa that has been reported to act as a structural element in Pa biofilms. Pf presence has been associated with resistance to antibiotics and poor outcomes in cystic fibrosis, though the underlying mechanisms are unclear. Here, we have investigated how Pf phages and sputum biopolymers impede antibiotic diffusion using human sputum samples and fluorescent recovery after photobleaching. We demonstrate that tobramycin interacts with Pf phages and sputum polymers through electrostatic interactions. We also developed a set of mathematical models to analyze the complex observations. Our analysis suggests that Pf phages in sputum reduce the diffusion of charged antibiotics due to a greater binding constant associated with organized liquid crystalline structures formed between Pf phages and sputum polymers. This study provides insights into antibiotic tolerance mechanisms in chronic Pa infections and may offer potential strategies for novel therapeutic approaches.

  View details for DOI 10.1101/2024.03.10.584330

  View details for PubMedID 38496625

• 13 Pseudomonas transmission dynamics revealed by prophage barcoding Journal of Cystic Fibrosis Pourtois , J., Haddock , N., Martinez , H., Schmidt , A., Gupta , A., Prakash , P., Chang , T., Amantullah , D., Milla , C., Secor , P., DeLeo , G., Bollyky , P., Burgener , E. 2024; 23

  View details for DOI 10.1016/S1569-1993(24)00856-7

• Rapid assessment of changes in phage bioactivity using dynamic light scattering. PNAS nexus Dharmaraj, T., Kratochvil, M. J., Pourtois, J. D., Chen, Q., Hajfathalian, M., Hargil, A., Lin, Y. H., Evans, Z., Oromí-Bosch, A., Berry, J. D., McBride, R., Haddock, N. L., Holman, D. R., van Belleghem, J. D., Chang, T. H., Barr, J. J., Lavigne, R., Heilshorn, S. C., Blankenberg, F. G., Bollyky, P. L. 2023; 2 (12): pgad406

  Abstract

  Extensive efforts are underway to develop bacteriophages as therapies against antibiotic-resistant bacteria. However, these efforts are confounded by the instability of phage preparations and a lack of suitable tools to assess active phage concentrations over time. In this study, we use dynamic light scattering (DLS) to measure changes in phage physical state in response to environmental factors and time, finding that phages tend to decay and form aggregates and that the degree of aggregation can be used to predict phage bioactivity. We then use DLS to optimize phage storage conditions for phages from human clinical trials, predict bioactivity in 50-y-old archival stocks, and evaluate phage samples for use in a phage therapy/wound infection model. We also provide a web application (Phage-Estimator of Lytic Function) to facilitate DLS studies of phages. We conclude that DLS provides a rapid, convenient, and nondestructive tool for quality control of phage preparations in academic and commercial settings.

  View details for DOI 10.1093/pnasnexus/pgad406

  View details for PubMedID 38111822

  View details for PubMedCentralID PMC10726995

• The Environmental Impact of Orthopaedic Surgery. The Journal of bone and joint surgery. American volume Saleh, J. R., Mitchell, A., Kha, S. T., Outterson, R., Choi, A., Allen, L., Chang, T., Ladd, A. L., Goodman, S. B., Fox, P., Chou, L. 2022

  Abstract

  ➤: There are a growing number of opportunities within the field of orthopaedic surgery to address climate change and investigate ways to promote sustainability.➤: Orthopaedic surgeons can take a proactive role in addressing climate change and its impacts within the areas of operating-room waste, carbon emissions from transportation and implant manufacturing, anesthetic gases, and water usage.➤: Future studies are needed to further these initiatives on quantifying and decreasing environmental impact and furthering sustainable use of our resources.

  View details for DOI 10.2106/JBJS.22.00548

  View details for PubMedID 36574633