Bacteriophages come in different sizes and shapes but most of them have the same basic features: a head or capsid and a tail. A bacteriophage’s head structure, regardless of its size or shape, is made up of one or more proteins which protectively coats the nucleic acid. Though there are some phages that don’t have a tail, most of them do have one attached to its head structure. How Bacteriophages Work n oder to infect a host cell, the bacteriophage attaches itself to the bacteria’s cell wall, specifically on a receptor found on the bacteria’s surface. Once it becomes tightly bound to the cell, the bacterial virus injects its genetic material (its nucleic acid) into the host cell. Depending on the type of phage, one of two cycles will occur – the lytic or the lysogenic cycle. During a lytic cycle, the phage will make use of the host cell’s chemical energy as well as its biosynthetic machinery in order to produce phage nucleic acids (phage DNA and phage mRNA) and phage proteins. Once the production phase is finished, the phage nucleic acids and structural proteins are then assembled. After a while, certain proteins produced within the cell will cause the cell wall to lyse, allowing the assembled phages within to be released and to infect other bacterial cells. Viral reproduction can also occur through the lysogenic cycle. The main difference between the two types of cycles is that during lysogeny, the host cell is not destroyed or does not undergo lysis. Once the host cell is infected, the phage DNA integrates or combines with the bacterial chromosome, creating the prophage. When the bacterium reproduces, the prophage is replicated along with the host chromosomes. Thus, the daughter cells also contain the prophage which carries the potential of producing phages. The lysogenic cycle can continue indefinitely (daughter cells with prophage present within continuing to replicate) unless exposed to adverse conditions which can trigger the termination of the lysogenic state and cause the expression of the phage DNA and the start of the lytic cycle. These adverse conditions include exposure to UV or mutagenic chemicals and desiccation. http://phages.org/bacteriophage/ Patients in hospitals, especially those on breathing machines, those with devices such as catheters, and patients with wounds from surgery or from burns are potentially at risk for serious, life-threatening infections. n hospitals, where the most serious infections occur, Pseudomonas can be spread on the hands of healthcare workers or by equipment that gets contaminated and is not properly cleaned. https://www.cdc.gov/hai/organisms/pseudomonas.html P. aeruginosa can develop resistance to antibacterials either through the acquisition of resistance genes on mobile genetic elements (i.e., plasmids) or through mutational processes that alter the expression and/or function of chromosomally encoded mechanisms. Both strategies for developing drug resistance can severely limit the therapeutic ...

1. Bacteriophages come in different sizes and shapes but most of
them have the same basic features: a head or capsid and a tail.
A bacteriophage’s head structure, regardless of its size or shape,
is made up of one or more proteins which protectively coats the
nucleic acid. Though there are some phages that don’t have a
tail, most of them do have one attached to its head structure.
How Bacteriophages Work
n oder to infect a host cell, the bacteriophage attaches itself to
the bacteria’s cell wall, specifically on a receptor found on the
bacteria’s surface. Once it becomes tightly bound to the cell,
the bacterial virus injects its genetic material (its nucleic acid)
into the host cell. Depending on the type of phage, one of two
cycles will occur – the lytic or the lysogenic cycle. During a
lytic cycle, the phage will make use of the host cell’s chemical
energy as well as its biosynthetic machinery in order to produce
phage nucleic acids (phage DNA and phage mRNA) and phage
proteins. Once the production phase is finished, the phage
nucleic acids and structural proteins are then assembled. After a
while, certain proteins produced within the cell will cause the
cell wall to lyse, allowing the assembled phages within to be
released and to infect other bacterial cells.
Viral reproduction can also occur through the lysogenic cycle.
The main difference between the two types of cycles is that
during lysogeny, the host cell is not destroyed or does not
undergo lysis. Once the host cell is infected, the phage DNA
integrates or combines with the bacterial chromosome, creating
the prophage. When the bacterium reproduces, the prophage is
replicated along with the host chromosomes. Thus, the daughter
cells also contain the prophage which carries the potential of
producing phages. The lysogenic cycle can continue indefinitely
(daughter cells with prophage present within continuing to
replicate) unless exposed to adverse conditions which can
trigger the termination of the lysogenic state and cause the
expression of the phage DNA and the start of the lytic cycle.

2. These adverse conditions include exposure to UV or mutagenic
chemicals and desiccation.
http://phages.org/bacteriophage/
Patients in hospitals, especially those on breathing machines,
those with devices such as catheters, and patients with wounds
from surgery or from burns are potentially at risk for serious,
life-threatening infections.
n hospitals, where the most serious infections
occur, Pseudomonas can be spread on the hands of healthcare
workers or by equipment that gets contaminated and is not
properly cleaned.
https://www.cdc.gov/hai/organisms/pseudomonas.html
P. aeruginosa can develop resistance to antibacterials either
through the acquisition of resistance genes on mobile genetic
elements (i.e., plasmids) or through mutational processes that
alter the expression and/or function of chromosomally encoded
mechanisms. Both strategies for developing drug resistance can
severely limit the therapeutic options for treatment of serious
infections.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2772362/
Multidrug-resistant Pseudomonas can be deadly for patients in
critical care. An estimated 51,000 healthcare-associated P.
aeruginosa infections occur in the United States each year.
More than 6,000 (13%) of these are multidrug-resistant, with
roughly 400 deaths per year attributed to these
infections. Multidrug-resistant Pseudomonas was given a threat
level of serious threat in the CDC AR Threat report.
https://www.cdc.gov/hai/organisms/pseudomonas.html
Antibacterial Resistance Trends
Presented in Table Table11 are rates of P. aeruginosa resistance

3. to several antipseudomonal drugs
(54, 95, 99, 100, 178, 211, 212). This summary is not meant to
be inclusive of all of the published literature, but rather
highlights data reported for isolates from several U.S.
surveillance studies since January 2000. If multiple years were
included in a study, the resistance rates for the most recent year
are presented in Table Table11.
Rates of antibacterial resistance among P. aeruginosa isolates
from hospitals and ICUs
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2772362/
Each set must be modified twice a year to retain its ability to
lyse a large proportion of the target species [5], [11]. P.
aeruginosa bacteriophages are numerous, and current knowledge
of their diversity shows that they are distributed in at least 7
genera of purely lytic phages (T7-like, ΦKMV-like, LUZ24-
like, N4-like, PB1-like, ΦKZ-like, JG004-like) in addition to a
similar number of temperate genera [12], [13]. Within each
genus, phages with a variety of different host spectra are
observed, in part at least reflecting differences in their tail-
associated adhesins
http://journals.plos.org/plosone/article?id=10.1371/journal.pone
.0060575
In- vitro and In- vivo Phage Trials
Running head: BACTERIOPHAGE THERAPY 1
BACTERIOPHAGE THERAPY 2

4. BACTERIOPHAGE THERAPY ON Pseudomonas aeruginosa
NAME: Roaya Alhawsawi
LIU
11/13/2016
BACTERIOPHAGE THERAPY ON Pseudomonas aeruginosa
Introduction
Bacteriophages are viruses that infect bacteria and replicate
within the bacterial cell wall. Most have double-stranded DNA
genomes found in heads with icosahedral symmetry, and their
tails vary in length. All bacteriophages are classified in the
order Caudovirales and belong to the families Myoviridae (long,
contractile tail), Siphoviridae (long, non-contractile tail)and
Podoviridae (short, non-contractile tail) (Harper & Enright,
2011). Bacteriophages were first discovered by Fredrick Twort
and Felix D’Herelle in 1915. Since then, bacteriophages started
being widely used for treating bacterial infections. This,
however, did not last long as chemical antibiotics were
discovered and preferred because bacteriophages were not well
understood and their efficacy was controversial. Things have
now changed due to the development of antibiotic-resistant
bacterial strains and bacteriophages have started being used

5. again. Comment by Daniel Ginsburg: You need more
background on phage. Life cycle. Lytic vs. lysogenic, etc.
Pseudomonas aeruginosa is a multidrug-resistant Gram-negative
bacteria that causes infections in the lungs of cystic fibrosis
patients and is a regular cause of hospital-acquired bacterial
pneumonia and ventilator-associated pneumonia. Since
bacteriophages are capable of reaching bacteria protected within
biofilms (such as those found in the lungs of patients with
cystic fibrosis), they are being considered as an alternative
treatment to antibiotics. Comment by Daniel Ginsburg: You
need more about P. aeruginosa. How many people get it every
year? It is lethal? Who is infected? You should get some
statistics from the CDC or WHO. I would also start with this
and then talk about phage.
You should also talk about the developent of drug resistance.
What are they resistant to?
Types of P.aeruginosa bacteriophages
Many P.aeruginosa bacteriophages have been discovered,
and they are classified into at least seven genera of lytic
phages. These include T7-like, ɸKMV-like, LUZ24- like, N4-
like, PB1-like, ɸKZ-like and JG004-like including a similar
number of temperate genera.(Essoh et al., 2013). Therapeutic
bacteriophage cocktails such as “pyophage” have also been
formulated. “Pyophage” contains many different phages that
target streptococcus, staphylococcus, Escherichia coli, proteus
and P. aeruginosa. Comment by Daniel Ginsburg: How are
these different from each other?
In- vitro and In- vivo Phage Trials
Many in-vitro and in-vivo phage trials have been conducted on
animal models and human patients. In in-vitro trials, the
potential of phages against P. aeruginosa strains in planktonic
cultures or biofilms isolates has been evaluated. Some of the
trials that have been done include: (1.) Fu et al. study of the
effect of lytic phages in the prevention of P. aeruginosa biofilm
formation in hydrogel-coated catheters, (2.) Pires et al. study

6. of biofilm control using a broad- host- range phage for P.
aeruginosa, (3.) Torres-Barceló et al. report on treatment using
a combination of Podoviridae phage LUZ7 and streptomycin
against P. aeruginosa PAO1 (Pires, Vilas Boas, Sillankorva, &
Azeredo, 2015). Comment by Daniel Ginsburg: Don’t just
list these. You need to talk a little bit about each of them.
What phage was used? What kind of system was it done in?
How were the phage delivered? How well did they work?
Some of the in- vivo trials that have been conducted on human
patients include: (1.) Wright et al. study of the the efficacy and
safety of a therapeutic phage preparation (Biophage-PA), (2.)
Sivera Marza et al. report on the successful topical use of phage
to treat a burn patient who had been colonized by P. aeruginosa
months after skin grafts had been applied and (3.) Merabishvili
et al. description of a quality-controlled small-scale production
of a phage cocktail (BFC-1) for use in human clinical
practice(Pires et al., 2015).
Discussion
Many bacteriophages have been isolated and their effects
against P. aeruginosa documented. A cocktail of ɸMR299-2 and
ɸNH-4 was effective in eliminating P. aeruginosa NH57388A
(mucoid) and P. aeruginosa MR299 (non- mucoid) strains when
growing as a biofilm on a cystic fibrosis bronchial epithelial
CFBE41o- cell line (Alemayehu et al., 2012). PAK-P or P3-
CHA reduced mortality and lung damage in mice with lethal
pneumonia caused by MDR P. aeruginosa (Rolain, Hraiech, &
Bregeon, 2015). Cocktail from “pyophage” showed lytic activity
against 70% of P. aeruginosa strains cultured in growth
medium, while PAK-P1 reduced mortality and lung inflation in
mice with lethal pneumonia caused by PAK bioluminescent P.
aeruginosa strain. Phage LUZ7 used with streptomycin inhibited
growth of the P. aeruginosa PAOI strain, while Engineered T7
phage with aiiA gene inhibited biofilm formation in the P.
aeruginosa PAOI strain. Phage PB-1 and tobramycin reduced
resistance to tobramycin in the P. aeruginosa PAOI strain
(Rolain et al., 2015). Phage P2-10Ab01 isolated from sewage

7. water in Abidjan could lyse two pyophage-resistant strains, C7-
6 and C9-5, and PAP3 was capable of lysogenization (Essoh et
al., 2013). Comment by Daniel Ginsburg: How effective?
Comment by Daniel Ginsburg: How were the phage
delivered? Comment by Daniel Ginsburg: What is this?
Comment by Daniel Ginsburg: You need a little more
detail about each of these. How did they work? How was the
experiment done?
Quorum Sensing Inhibition
Since hydrolyzing acyl homoserine lactonases can decrease in
vivo virulence of P. aeruginosa and in vitro biofilm production,
bacteriophages can be modified genetically to produce
lactonase, which would facilitate inhibition of P.aeruginosa
biofilm production (Rolain et al., 2015). … Comment by
Daniel Ginsburg: How do these work?
I don’t understand what this has to do with quoroum sensing.
Mechanism of Bacteriophage Resistance
Even though bacteriophage therapy has made headway in the
treatment of bacterial infections, the issue of bacteria that are
resistant to phages has come up. The mechanisms of bacterial
resistance to phages drive the evolution of both bacteria and
bacteriophages, and ongoing isolation of new bacteriophages
targeting various hosts and host receptors is, therefore,
necessary. Bacterial resistance to phages may involve three
mechanisms: inhibition of the adsorption of phages on the
bacteria and injection of DNA, use of restriction enzymes to
degrade phage DNA and the CRISPR- Cas system that gives
bacteria immunity against the phages (Essoh et al., 2013). The
CRISPR-Cas mediates interference against certain types of
temperate phages. However, some phages found in the Mu- like
genus have been found to carry genes that can inactivate the
system.
Challenges Facing Use of Bactereophages
The potential disadvantages of bacteriophages can be
categorized into four: phage selection, phage-host- range

8. limitation uniqueness of phages as pharmaceuticals and
unfamiliarity with phages (Loc-Carrillo & Abedon, 2011). Not
all phages are good for therapeutics since some of them may
cause the development of immunogenic reactions due to large
uncontrolled amounts of phages in circulation (Paul et al.,
2011). However, use of bacteriophages devoid of endotoxins
should not induce a strong stimulation of the pro-inflammatory
markers (Morello et al., 2011).
Conclusion
In this therapy, isolation of bacteriophage using the strain from
the patient is preferred over using readymade phages (Henry,
Lavigne, & Debarbieux, 2013). Moreover, bioluminescent
bacteria can be used to compare several bacteriophages, so as to
establish candidates for therapeutics based on their real in vivo
efficacy instead of they are in vitro performance (Debarbieux et
al., 2010). With a combination of proper selection of phages,
proper formulation and improved clinical understanding of how
phages work, bacteriophage could easily become the most
effective way for treating bacterial infections. Comment by
Daniel Ginsburg: As I see it, everything up to this point is
Body. This would be your Discussion and it needs to be
expanded. Can you talk more about isolating phage from
patients, using bioluminescent bacteria, etc.?
References
Alemayehu, D., Casey, P. G., McAuliffe, O., Guinane, C. M.,
Martin, J. G., Shanahan, F., … Hill, C. (2012). Bacteriophages
φMR299-2 and φNH-4 can eliminate Pseudomonas aeruginosa
in the murine lung and on cystic fibrosis lung airway cells.
mBio, 3(2), e00029-12. http://doi.org/10.1128/mBio.00029-12
Debarbieux, L., Leduc, D., Maura, D., Morello, E., Criscuolo,
A., Grossi, O., … Touqui, L. (2010). Bacteriophages can treat
and prevent Pseudomonas aeruginosa lung infections. The
Journal of Infectious Diseases, 201(7), 1096–104.
http://doi.org/10.1086/651135
Essoh, C., Blouin, Y., Loukou, G., Cablanmian, A., Lathro, S.,
Kutter, E., … Qimron, U. (2013). The Susceptibility of

9. Pseudomonas aeruginosa Strains from Cystic Fibrosis Patients
to Bacteriophages. PLoS ONE, 8(4), e60575.
http://doi.org/10.1371/journal.pone.0060575
Harper, D. R., & Enright, M. C. (2011). Bacteriophages for the
treatment of Pseudomonas aeruginosa infections. Journal of
Applied Microbiology, 111(1), 1–7.
http://doi.org/10.1111/j.1365-2672.2011.05003.x
Henry, M., Lavigne, R., & Debarbieux, L. (2013). Predicting in
vivo efficacy of therapeutic bacteriophages used to treat
pulmonary infections. Antimicrobial Agents and Chemotherapy,
57(12), 5961–5968. http://doi.org/10.1128/AAC.01596-13
Loc-Carrillo, C., & Abedon, S. T. (2011). Pros and cons of
phage therapy. Bacteriophage, 1(2), 111–114.
http://doi.org/10.4161/bact.1.2.14590
Morello, E., Saussereau, E., Maura, D., Huerre, M., Touqui, L.,
& Debarbieux, L. (2011). Pulmonary bacteriophage therapy on
Pseudomonas aeruginosa cystic fibrosis strains: first steps
towards treatment and prevention. PloS One, 6(2), e16963.
http://doi.org/10.1371/journal.pone.0016963
Paul, V., Sundarrajan, S., Rajagopalan, S., Hariharan, S.,
Kempashanaiah, N., Padmanabhan, S., … Watson, J. (2011).
Lysis-deficient phages as novel therapeutic agents for
controlling bacterial infection. BMC Microbiology, 11(1), 195.
http://doi.org/10.1186/1471-2180-11-195
Pires, D. P., Vilas Boas, D., Sillankorva, S., & Azeredo, J.
(2015). Phage Therapy: a Step Forward in the Treatment of
Pseudomonas aeruginosa Infections. Journal of Virology,
89(15), 7449–56. http://doi.org/10.1128/JVI.00385-15
Rolain, J.-M., Hraiech, S., & Bregeon, F. (2015).
Bacteriophage-based therapy in cystic fibrosis-associated
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