| Autor: |
Menon ND; School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kerala, India.; Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, UC San Diego, La Jolla, California, USA., Penziner S; Division of Infectious Diseases and Global Public Health, Department of Medicine, UC San Diego, La Jolla, California, USA., Montaño ET; Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, UC San Diego, La Jolla, California, USA., Zurich R; Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, UC San Diego, La Jolla, California, USA., Pride DT; Division of Infectious Diseases and Global Public Health, Department of Medicine, UC San Diego, La Jolla, California, USA.; Department of Pathology, UC San Diego, La Jolla, California, USA., Nair BG; School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kerala, India.; Tata Institute for Genetics and Society (TIGS), Bangalore, Karnataka, India., Kumar GB; School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kerala, India.; Tata Institute for Genetics and Society (TIGS), Bangalore, Karnataka, India., Nizet V; Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, UC San Diego, La Jolla, California, USA.; Skaggs School of Pharmacy and Pharmaceutical Sciences, UC San Diego, La Jolla, California, USA. |
| Abstrakt: |
Bacteriophage (phage) therapy is an alternative to traditional antibiotic treatments that is particularly important for multidrug-resistant pathogens, such as Pseudomonas aeruginosa. Unfortunately, phage resistance commonly arises during treatment as bacteria evolve to survive phage predation. During in vitro phage treatment of a P. aeruginosa-type strain, we observed the emergence of phage-resistant mutants with brown pigmentation that was indicative of pyomelanin. As increased pyomelanin (due to hmgA gene mutation) was recently associated with enhanced resistance to hydrogen peroxide and persistence in experimental lung infection, we questioned if therapeutic phage applications could inadvertently select for hypervirulent populations. Pyomelanogenic phage-resistant mutants of P. aeruginosa PAO1 were selected for upon treatment with three distinct phages. Phage-resistant pyomelanogenic mutants did not possess increased survival of pyomelanogenic Δ hmgA in hydrogen peroxide. At the genomic level, large (~300 kb) deletions in the phage-resistant mutants resulted in the loss of ≥227 genes, many of which had roles in survival, virulence, and antibiotic resistance. Phage-resistant pyomelanogenic mutants were hypersusceptible to cationic peptides LL-37 and colistin and were more easily cleared in human whole blood, serum, and a murine infection model. Our findings suggest that hyperpigmented phage-resistant mutants that may arise during phage therapy are markedly less virulent than their predecessors due to large genomic deletions. Thus, their existence does not present a contraindication to using anti-pseudomonal phage therapy, especially considering that these mutants develop drug susceptibility to the familiar FDA-approved antibiotic, colistin. |
