A WINDOW OF OPPORTUNITY TO CONTROL THE BACTERIAL PATHOGEN PSEDOMONAS AERUGINOSA COMBINING ANTIBIOTICS AND PHAGES

Clara T.Barcelo, Flor I. Sanchez, Marie Vasse et. al.

http://www.pseudomonas.com/

Presentation by: Juan Barrera

Antibiotic resistance is becoming an increasingly problematic issue Antibiotics are the

most effective defense against bacterial infections.

Rapid adaptation of bacteria to antibiotics leads to resistance.

There is mounting interest in search of alternatives to antibiotics. http://www.pulsetoday.co.uk/Pictures/web/w/n/x/

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Pseudomonas aeruginosa is responsible for a variety of

nosocomial infections Gram negative. Poses a threat to

cystic fibrosis patients.

Source of hospital acquired pneumonia.

Causes chronic lung infections.

Infects wounds and burns.

http://upload.wikimedia.org/commons/e/ec/Pseudomonas_aeruginosa_culture.JPG

Phage therapy is used to treat bacterial pathogens

Provide host specificity.

More specific than antibiotics.

Phages are able to inject genetic material inside host.

LUZ7 phage has reduced bacterial population size of P. aeruginosa.

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Experiment designed to test individual and combined treatments

P.aeruginosa (PAO1) treated with LUZ7 bacteriophage.

Pathogen treated with streptomycin.

Treatment with both streptomycin and LUZ7.

Results observed by counting number of different growing colonies (CFU).

Figure 1. Overview of experimental design

Barcelo et. al. (2014)

Combined phage-strep treatment caused reduction in bacterial density

Single treatments of phage and antibiotic reduced bacterial density over the first 24 hours.

Densities rebounded to control levels by the 70 hour mark

Combined treatment caused significant reduction in density without regrowth.

Bacterial density reduction was stronger when antibiotic was added with a 12 hour delay.

Streptomycin dose had no significant effect on final density.

Figure 2. Changes in bacterial density over time

Barcelo et. al. (2014)

There is a positive synergistic interaction between phage and antibiotic

Densities were lower than expected.

The combined treatment was most significant for the 12h antibiotic addition.

Delay of antibiotic addition resulted in strongest negative impact.

Figure 3. Final bacterial densities

Barcelo et. al. (2014)

Final bacterial populations exhibited resistance

Bacteria treated from streptomycin evolved higher levels of resistance.

Single-strep treatment resistance reached maximum levels.

Resistance values were lower for populations where streptomycin was added to the phage with a 12h delay.Barcelo et. al.

(2014)

Figure 4. Resistance of final bacterial populations.

Bacteria from phage treatments were more resistant as compared

with bacteria with no phage treatment

Absence of phage produced a decrease in resistance.

Previously exposed bacteria exhibit resistance towards ancestral phage.

Figure 4. Resistance of final bacterial populations.

Barcelo et. al. (2014)

Treatment with evolved phage showed difference when compared

with ancestral phage

Resistance against evolved phage was lower as compared with ancestral phage.

Data suggests adaptation of phage to bacteria.

Figure 4. Resistance of final bacterial populations.

Barcelo et. al. (2014)

Combination of antibiotics and phages is a enticing possibility

Combined treatments lead to synergistic suppression of bacterial density and less resistance.

Bacteria most affected when antibiotic added at the time when phages had their strongest impact.

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Conclusion The study provides evidence of the

effectiveness of antibiotic-phage treatment on P.aeruginosa pathogen. It also suggests a specific window of opportunity in which the antibiotic can be added and have the most effect.

ReferencesBetts A, Vasse M, Kaltz O, Hochberg ME (2013) Back to the future: evolving bacteriophages to increase their effectiveness against the pathogen Pseudomonas aeruginosa PAO1. Evol. Appl 6: 1054–1063. doi: 10.1111/eva.12085

Chan BK, Abedon ST, Loc-Carrillo C (2013) Phage cocktails and the future of phage therapy. Future Microbiol 8: 769–783. doi: 10.2217/fmb.13.47

Escobar-Paramo P, Gougat-Barbera C, Hochberg ME (2012) Evolutionary dynamics of separate and combined exposure of Pseudomonas fluorescens SBW25 to antibiotics and bacteriophage. Evol. Appl 5: 583–592. doi: 10.1111/j.1752-4571.2012.00248.x

Jesus, Blazquez, Oliver Antonio, and Gomez-Gomez Jose-Maria. "Mutation And Evolution Of Antibiotic Resistance: Antibiotics As Promoters Of Antibiotic Resistance?." Current Drug Targets 3.4 (2002): 345-349. Academic Search Complete. Web. 19 Oct. 2014.

Rodriguez-Rojas A, Rodriguez-Beltran J, Couce A, Blazquez J (2013) Antibiotics and antibiotic resistance: A bitter fight against evolution. Int. J. Med. Microbiol 303: 293–297. doi: 10.1016/j.ijmm.2013.02.004

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http://news.bbcimg.co.uk/media/images/66413000/jpg/_66413365_c0147229-bacteriophages_leaving_host_cell,_artwork-spl.jpg

http://www.pseudomonas.com/

http://upload.wikimedia.org/commons/e/ec/Pseudomonas_aeruginosa_culture.JPG

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