This document discusses the history and potential applications of bacteriophage therapy. It begins by introducing bacteriophages and their ability to lyse bacteria. It then provides examples of different types of phages and describes their life cycles. The document discusses the discovery of phages in the early 20th century and their use in the former Soviet Union to treat bacterial infections. It notes that antibiotic resistance has renewed interest in phage therapy as an alternative approach. The advantages and disadvantages of phage therapy over antibiotics are presented. The document concludes by stating that further studies are needed but that phages show promise as tailored treatments for multidrug-resistant bacteria.

1. Bacteriophage Therapy old
idea new application
Edited by
Muslim Dhaher
2012

2. Introduction
The emergence of pathogenic bacteria resistant to most,
if not all, currently available antimicrobial agents has
become critical problem in modern medicine, particularly
because of the concomitant increase in
immunosuppressed patients. The concern that humankind
is reentering the ―preantibiotics‖ era has become very
real, and the development of alternative antiinfection
modalities has become one of the highest priorities of
modern medicine and biotechnology

3. Bacteriophage definition
Bacteriophages are viruses that parasitize bacteria. Bacteriophages
were jointly discovered by Frederick Twort (1915) in England and
by Felix d'Herelle (1917) at the Pasteur Institute in France. Felix
d'Herelle coined the term ―Bacteriophage‖. Bacteriophage means
to eat bacteria, and are called so because virulent bacteriophage
can cause the compete lysis of a susceptible bacterial culture. They
are commonly referred as ―phage‖. Phages are obligate
intracellular parasites that multiply inside bacteria by making
use of some or all of the host biosynthetic machinery. They occur
widely in nature and can readily be isolated from feces and
sewage. There are at least 12 distinct groups of bacteriophages,
which are very diverse structurally and genetically .

4. Examples of phages
 T-even phages such as T2, T4 and T6 that
infect E.coli
 Temperate phages such as lambda and mu
 Spherical phages with single stranded
DNA such as PhiX174
 Filamentous phages with single stranded
DNA such as M13
 RNA phages such as Q- beta

5. Phage life cycle
The following phases can be distinguished in the lytic
bacteriophage developmental cycle:
1. Adsorption of the phage on the bacterial cell by binding to
a specific receptor.
2. Injection of the nucleic acid into the bacterium.
3. Expression of the phage early genes, synthesis of
early proteins, most involved in the shutting down of
the host bacterium systems and phage genome
replication.

6. 4. Replication of the phage genome.
5. Expression of the phage late proteins involved
in the formation of new phage particles and lysis
of the host bacterium.
6. Assembly of the phage heads and tails and
packaging of the genome.
7. Lysis of the host bacterium and release of the
new phage progeny

7. Schematic illustration of phage-induced
bacteriolysis

8. The Problem
Multidrug resistant bacteria are a serious health problem
these days. Persistent use of broad spectrum
antibiotics leads to further drug resistance in these
organism. Rigorous research activities are ongoing to
develop alternate methods of treatment of infections
caused by these microorganisms. Phage therapy seems
to be a good option for this problem.

9. Resistance is on the rise. An increasing number of pathogens
are resistant to one or more drugs used to treat the diseases
they cause!. Indeed, many diseases common in developing
countries— including malaria, pneumonia, cholera, and
dysentery—are increasingly caused by strains that are
resistant to multiple drugs. This is true for diseases such as
tuberculosis (TB) and infections such as Staphylococcus
aureus (S. aureus) that afflict rich countries as well as
poor ones.
The problem is global: Drug-resistant TB is spreading
rapidly to countries where it has not been seen before

10. The ability of the phages to kill the bacterial
cells at the end of the infectious cycle is the
cornerstone of the idea of using phages as
therapeutic agents.

11. Electron micrographs of tailed phages. KVP20, KVP40, and
KVP241 are Vibrio phages belonging to family Myoviridae;
fMR11 is a Staphylococccus phage belonging to family
Siphoviridae.

12. First Era of Bacteriophage
 Ernest Hankin, a British bacteriologist, reported in 1896 on
the presence of marked antibacterial activity (against Vibrio
cholerae) which he observed in the waters
of the Ganges and Jumna rivers in India, and he suggested
that an unidentified substance (which passed through fine
porcelain filters and was heat labile) was responsible for
this phenomenon
 Russian bacteriologist Gamaleya observed a similar
phenomenon while working with Bacillus subtilis and the
observations of several other investigators are also thought
to have been related to the bacteriophage phenomenon
However, none of these investigators further explored their
findings

13. Frederick Twort, a medically trained bacteriologist
for various reasons—including financial difficulties
Twort did not pursue this finding from England,
reintroduced the subject. The discovery or
rediscovery of bacteriophages by d‘Herelle is
frequently associated with an outbreak of severe
hemorrhagic dysentery among French troops
stationed at Maisons-Laffitte (on the outskirts of
Paris) in July-August 1915, althoug d‘Herelle
apparently first observed the bacteriophag
phenomenon in 1910 while studying microbiologic
means of controlling an epizootic of locusts in
Mexico. Several soldiers were hospitalized.

14. Another thought came to me also.
If this is true, the same thing will
have probably occurred in the sick
man. In his intestine, as in my
test-tube, the dysentery bacilli will
have dissolved away under the
action of their parasite. He should
now be cured

15. d‘Herelle was assigned to conduct an investigation of the
outbreak. During these studies, he made bacterium-free
filtrates of the patients‘ fecal samples and mixed and
incubated them with Shigella strains isolated from the
patients. A portion of the mixtures was inoculated into
experimental animals (as part of d‘Herelle‘s studies on
developing a vaccine against bacterial dysentery), and a
portion was spread on agar medium in order to observe
the growth of the bacteria. It was on these agar cultures
that d‘Herelle observed the appearance of small, clear
areas, which he initially called taches, then taches vierges,
and, later, plaques (68). D’Herelle’s findings were
presented during the September 1917 meeting of the
Academy of Sciences, and they were subsequently
published in the meeting‘s proceedings. In contrast to
Hankin and Twort, d‘Herelle had little doubt about the
nature of the phenomenon, and he proposed that it was
caused by a virus capable of parasitizing bacteria.

16. What is bacteriophage thearapy
Phage therapy is the use of Bacteriophage viruses to combat bacteria
instead of using antibiotics. Bacteriophages only attack bacteria
nothing else which makes it useful in medicine as it does not affect
the patient only the bacteria, it also has the bonus of being very
specific to with bacteria it will attack. Phage therapy is the
therapeutic use of bacteriophages to treat pathogenic bacterial
infections . Although extensively used and developed mainly in
former Soviet Union countries for about ninty years , this method
of therapy is still being tested elsewhere for treatment of a variety
of bacterial and poly – microbial biofilms infections and has not
yet been approved in countries other than Georgia . Phage therapy
has mainly potential applications in human medicines , dentistry ,
veterinary science and agricujture .

17. An important benefit of phage therapy is that
bacteriophage can be much more specific than
more common drugs so can be chosen to be
harmless to not only host organism but also
other beneficial bacteria . A smaller effective
dose can be used in phage therapy . On the
other hand specificity also a disadvantage , a
phage will only kill a bacterium if it is a match
to the specific strain . Thus mixture are often
applied to improve the chances of success or
samples can be taken and an appropriate phage
identified and grown . Phages tend to be more
successful than antibiotics where there is a
biofilm covered by a polysaccharide layer ,
which antibiotics typically cannot penetrate .

18. Bacteriophage ignoration
It is interesting to note that phage therapy ceased to be used in
the West with the advent of the antibiotic era but has been
rediscovered because of the rise in antimicrobial-resistant bacteria.
While the study and exploitation of phages flourished in the
West, particularly in the development of molecular tools, its use
in the former Soviet Union as a therapeutic tool has remained
steady for over 80 years. Phage therapy has been the subject of
numerous recent review articles (4-16). (Regrettably, the present
article largely ignores the literature from the former Soviet
Union because of language problems and lack of detail provided
in the published studies.

19. Importance of phage
Epidemiological fingerprinting of bacterial isolates (phage typing)
In epidemiological work, it is necessary to track individual bacterial
isolates from clinical specimens to their source (47). This is
accomplished by fingerprinting the strains using a wide variety
of phenotype- or genotype-based typing methods. One of the classical
procedures is phage typing, which is still used in Canada at the
Laboratory for Foodborne Zoonoses (Guelph, Ontario) and the
National Microbiology Laboratory (Winnipeg, Manitoba), for
Salmonella and E coli strains. This procedure involves exposing the
bacterial isolate to a battery of ‗typing‘ phages, and recording the
pattern and degree of lysis. This approach offers import advantages,
including the incredible specificity of phage, and a high degree of
typability and reproducibility. Furthermore, in contrast to serotyping
and pulsed field gel electrophoresis analysis, phage typing is
relatively inexpensive.

20. Use of bacteriophages to express peptides and proteins
(phage display) Several systems have been developed to create
peptide or protein fusions on capsid proteins of bacteriophages
of coliphages lambda (59,60), M13 (61), T7 (62-64) and T4
(65). The M13 and T7 systems have been commercialized.
These extremely elegant molecular tools have been used to
identify antibody binding epitopes (66-68), amino acid
residues involved in protein-protein interactions (69-71),
peptides that mimic nonpeptide ligands (72), enzyme
substrates and inhibitors, and have even been used to express
proteins. One major advantage of this system over standard
protein chemistry is that the sequence of the peptide insert can
be rapidly aninexpensivel determined by DNA sequencing.

21. New phage diagnostic tools In addition to the
classical uses of phages in molecular biology
and diagnostic microbiology, new tools have
been developed. The phage amplification
assay, for example, is a simple yet elegant way
to identify the presence of specific pathogens
in food products. The intracellular replication
of phage and concomitant lysis of the
susceptible bacteria leads to an increase in free
phage, which can be easily measured

22. SPECIAL ADVANTAGES
Phages have specific properties which give them
advantages as therapeutic agents. They are self-
replicating as well as self-limiting. They continue
to multiply and penetrate deeper as long as local
infection as present. This is in sharp contrast to
antibiotics which decrease in concentration below
the site of infection. Phages are lytic against
specific bacteria so they can be targeted more
specifically than antibiotics which are active
against a group of bacteria. Phages do not harm
normal intestinal microflora.6 Antibiotics have
side effects which can be serious. But phages have
been used in

23. millions of patients without any reported side
effects. Phages can be used prophylactically
as well as in established infections. The
self-perpetuating nature of phages in the
presence of susceptible bacteria, makes
multiple administrations7,8 unnecessary. It
also allows transfer of administered phages
between animals in a farmyard.9,1

24. The advantages and
disadvantages
of phage therapy
Advantage Remark
Phages are very specific and do not As a result, there are no side effects
harm the useful bacteria that live in like diarrhoea or secondary infections
and on the body. such as those that occur in treatment
with antibiotics.
Due to their specificity, phages do
not cause a selection of resistances
in the useful bacteria that live in and
on the body.
We are constantly ingesting Because they are harmless, phages
phages. In general, they are can be used for combating harmful
harmless to human beings. When bacteria in fattening animals and
well-purified phages are used, few food.
side effects have been described
for all types of administration

25. Some resistant Antibiotic-resistant
bacteria that have been bacteria are generally
selected during not less virulent.
treatment with phages
are less virulent and
can be fought by the
immune system
Phages are also active
against bacteria that
have become resistant to
antibiotics
Phages can be
genetically modified in
order to make up for
some of their
disadvantages
Phages are an Bacteria that have
‘intelligent’ drug. They become resistant to a
multiply at the site of the certain antibiotic often
infection until there are become resistant to
no more bacteria. Then other drugs more easily.
they are excreted

26. Phage disadvantage
 The great specificity of phages is a
disadvantage when the exact species of
infecting bacteria is unknown or if there
is a multiple infection.
 Bacteria have a type of ‘immune system’
that destroys the hereditary material of
some penetrating phages. Only suitable
phages can conquer this ‘immune
system’
 Infections whose agents are hidden in
the interior of human cells may be
inaccessible to phages

27. Results of bacteriophage
treatment
Septicemia S. aureus, E.
coli,
Klebsiella,
Proteus,
Pseudomonas
Purulent otitis S. aureus,
media Klebsiella,
Pseudomonas
Varicose S. aureus, E.
ulcers of coli,
lower Klebsiella,
extremities Proteus,
Pseudomonas
Mucopurulent S. aureus, E.
chronic coli,
bronchitis, Klebsiella,
laryngitis, Proteus,
rhinitis Pseudomonas

28. Bronchopneumoni S. aureus, E. coli, 57 47
a, Klebsiella,
empyema Proteus,
Pseudomonas
Pleuritis with fistula S. aureus, E. coli,
Klebsiella, Proteus,
Pseudomonas
Suppurative S. aureus, E. coli,
peritonitis Klebsiella,
Enterobacter,
Proteus,
Pseudomonas
Urinary tract S. aureus, E. coli,
infections Klebsiella, Proteus,
Pseudomonas
Pyogenic arthritis S. aureus, E. coli,
and Klebsiella, Proteus,
myositis Pseudomonas
Suppurative osteitis S. aureus, E. coli,
after Klebsiella, Proteus,
bone fractures Pseudomonas

29. CONCLUSION
In medicine today phages find many applications. They
are used for typing of clinical bacterial strains for in situ
bacterial detection through labelled phages, (TB, Listeria),
phage display system for vaccines, control of food pathogens
and for drug and gene delivery using defective phage with
targeted receptor. Phage therapy for eliminating multidrug
resistant bacteria is gaining importance. However, there is a
need to carry out further studies on phages as therapeutic
agents using specific phage strains against the corresponding
bacterial hosts. Phages should be essentially free of
contaminating bacterial toxin and also capable of evading
the reticulendothelial system

30. Thanks for your attention