The isolation and characterization of two Stenotrophomonas maltophilia bacteriophages capable of cross-taxonomic order infectivity.
BACKGROUND
A rapid worldwide increase in the number of human infections caused by the extremely antibiotic resistant bacterium Stenotrophomonas maltophilia is prompting alarm. One potential treatment solution to the current antibiotic resistance dilemma is "phage therapy", the clinical application of bacteriophages to selectively kill bacteria.


RESULTS
Towards that end, phages DLP1 and DLP2 (vB_SmaS-DLP_1 and vB_SmaS-DLP_2, respectively) were isolated against S. maltophilia strain D1585. Host range analysis for each phage was conducted using 27 clinical S. maltophilia isolates and 11 Pseudomonas aeruginosa strains. Both phages exhibit unusually broad host ranges capable of infecting bacteria across taxonomic orders. Transmission electron microscopy of the phage DLP1 and DLP2 morphology reveals that they belong to the Siphoviridae family of bacteriophages. Restriction fragment length polymorphism analysis and complete genome sequencing and analysis indicates that phages DLP1 and DLP2 are closely related but different phages, sharing 96.7 % identity over 97.2 % of their genomes. These two phages are also related to P. aeruginosa phages vB_Pae-Kakheti_25 (PA25), PA73, and vB_PaeS_SCH_Ab26 (Ab26) and more distantly related to Burkholderia cepacia complex phage KL1, which together make up a taxonomic sub-family. Phages DLP1 and DLP2 exhibited significant differences in host ranges and growth kinetics.


CONCLUSIONS
The isolation and characterization of phages able to infect two completely different species of bacteria is an exciting discovery, as phages typically can only infect related bacterial species, and rarely infect bacteria across taxonomic families, let alone across taxonomic orders.
Department of Biological Sciences, 6-065 Centennial Centre for Interdisciplinary Science, University of Alberta, Edmonton, AB, T6G 2E9, Canada. dlpeters@ualberta.ca.
Danielle L
DL
Peters
Department of Biological Sciences, 6-065 Centennial Centre for Interdisciplinary Science, University of Alberta, Edmonton, AB, T6G 2E9, Canada. khlynch@ualberta.ca.
Karlene H
KH
Lynch
Department of Agricultural, Food and Nutritional Science, University of Alberta, 1400 College Plaza, Edmonton, AB, T6G 2C8, Canada. stothard@ualberta.ca.
Paul
P
Stothard
Department of Biological Sciences, 6-065 Centennial Centre for Interdisciplinary Science, University of Alberta, Edmonton, AB, T6G 2E9, Canada. jon.dennis@ualberta.ca.
Jonathan J
JJ
Dennis
D001433:Bacteriolysis; D001435:Bacteriophages / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity*; D004260:DNA Repair; D004261:DNA Replication; D016679:Genome, Viral; D058507:Host Specificity; D058977:Molecular Sequence Annotation; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D015203:Reproducibility of Results; D020615:Stenotrophomonas maltophilia / Q000821:virology*; D014771:Virion / Q000254:growth & development