2. History
• Cohn (1875) first observed and described a
branching filamentous microorganism in the
‘concretions’ (coagulated mass) taken from a
lacrimal canal, later identified as Actinomyces
israelii
• Bollinger (1877) first reported the yellow granules
in jaw of the cattle
• In 1878, Israel described the first human case
• In 1879, Hartz observed the microscopic
appearance of granules of Actinomyces and
suggested the name Actinomyces bovis
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3. Morphology
• Gram-positive filamentous
organisms with branching rods
• In artificial media.. short bacilli
or cocci forms
• During infection, the bacteria
can produce yellow coloured
granules (sulphur granule),
commonly found in the pus as
‘opaque speck’ and are visible
under naked eye. The granules
are usually soft and easily
broken under light pressure,
but sometimes are tough or
calcified
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4. Morphology
• The granules are composed of club
shaped bodies, arranged radially with
their narrow ends towards the centre.
So, the bacteria are also known as ‘ray
fungus’
• In the centre of the club, filamentous
masses of Gram positive bacteria with
some bacilli or cocci form are found.
Together the club like processes and
bacterial masses are known as ‘rosette’
• The club is composed of calcium
phosphate and inflammatory debris. It
occurs as a result of the bacterial
phosphatase activity in response to
inflammation. However, the clubs are
more prominently observed in tissue
section than the granules.
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5. Properties
• Actinomyces are non-motile, non-sporing and
non-acid fast
• facultative anaerobic and capnophilic (require
CO2 for growth)
• Classification:
Family- Actinomycetes;
The genus Actinomyces contains more than 30
species
A. bovis and A. israelii are the most common
pathogens in animals and human
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6. Properties
• Resistance: 60°C temperature for 20 minute exposure
and autoclaving (120°C for 15 minute) is lethal to
Actinomyces. The sulphur granules in pus remain viable
after being air-dried in test tubes for 18-22 days.The
bacteria are susceptible to common disinfectants like
phenol, cresol etc
• Natural habitat: Most of the Actinomyces are obligate
parasites on the mucous membrane of mouth,
pharynx, tonsils, teeth surface and alimentary tract of
different animals and humans. Most of the infections
are endogenous in origin. The bacteria do not survive
in the environment for a long time.
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7. Isolation, growth and colony
characteristics
• Actinomyces can be isolated in the media
enriched with blood (chocolate blood agar) or
serum
• Specific media are Garrod’s media, brain heart
infusion agar with or without sheep blood (10%),
Brucella blood agar with haemin and vitamin K1,
phenylethyl alcohol or mupirocin-metronidazole
blood agar
• No growth is observed in Sabouraud’s dextrose
agar at room temperature
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8. Isolation, growth and colony
characteristics
• The incubation is performed at 37°C for
4-6 days with 5% CO2 tension
• Under aerobic condition, most of the
colonies appear in the sub-surface layer
of the media, where oxygen tension is
low
• The colonies of A. bovis are non-
haemolytic, round, flat, pale yellow in
colour, 1 mm in diameter, non-
filamentous or filamentous with irregular
edges. Colonies can adhere with the solid
medium.
• A. viscosus : ‘spider colony’ / ‘Molar
tooth colony’
Molar tooth colony
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10. Antigenic characteristics
• Each of the species can be sub-divided into at
least two serotypes.
• Two serotypes of A. bovis show little or no
cross reaction with each other. Serotype 1 and
2 produce non-filamentous and filamentous
colonies, respectively.
• In A. viscosus, serotype 1 is restricted to
animals, whereas serotype 2 is typically
detected in humans. The two serotypes (1 and
2) are serologically distinct.
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11. Toxins and virulence factors produced
No true exotoxin is produced by Actinomyces
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12. Transmission
Actinomycosis in animals and human is an
endogenous infection. The bacteria have natural
habitat in the mucous membrane of mouth,
pharynx, tonsils and teeth surface. The bacteria
can enter the underlying deeper tissues either
through dental alveoli or through the damaged
mucosa by thorny feed, foreign bodies,
accidental trauma, and injury. Rarely animal bite
is another way of transmission in susceptible
animals and human.
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13. Pathogenesis
After entry into the deeper tissues of the buccal cavity,
A. bovis grows in the tongue, pharynx, and subcutaneous
tissues of the head and neck
The areas of suppuration are produced containing
bacteria and neutrophils in the centre. It is surrounded
by granulation, fibrosis and infiltration of mononuclear
cells. Neutrophils accumulate at the site due to
secreation of chemotactic molecules by Actinomyces
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14. Pathogenesis
Suppurative necrosis is observed in the
esophagus and reticulum with the production of
thick green / yellow coloured pus. Sometimes
excess pus may overflow the surface through the
sinus or fistula
Infection may disseminate into the lungs, lymph
nodes, liver, vertebrae and bones through the
blood.
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15. Pathogenesis
Osteomyelitis develops and
bones become porous
(honeycombed) with pus
filled sinuses.
Old bones are replaced with
new bones.
Mandibular fractures are
also observed. Animals
cannot chew properly.
However, in other tissues
after dissemination infection
does not establish.
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20. Diagnosis
Clinical samples: Pus, aspirates
from the unopened lesion
preferably with sulphur
granules can be collected as
ante-mortem samples. Fine
needle aspiration biopsy
(FNAB) can be carried out from
the depth of the suspected
actinomycotic growth and also
from the mandibular lymph
node with the help of the long
needle. Tissue biopsies are
collected in 10% formalin for
histopathology.
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21. Direct Examination
Yellow coloured ‘sulphur granules’ are observed in the pus/
exudate
Granules are washed with distilled water in a sterile petri dish
Granules are placed in one drop of 10% KOH in a glass slide
Granules are gently crushed with cover slip and observed under
low power objective of microscope
‘Club shaped’ bacterial micro-colonies are found
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22. Diagnosis
• Isolation of bacteria from clinical samples
• Serological tests: Immunodiffusion,
fluorescent antibody test (FAT) can be
performed for the detection of A. bovis
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23. Prevention and Control
• No Vaccine
• Isolation or disposal of infected animals with
oral lesions and salivation
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25. Nocardiosis
• Nocardiosis primarily presents as a pulmonary
disease or brain abscess in the U.S. In Latin
America, it is more frequently seen as the
cause of a subcutaneous infection, with or
without draining abscesses. It can even
present as a lesion in the chest wall that
drains onto the surface of the body similar to
actinomycosis. Brain abscesses are frequent
secondary lesions.
Dr.T.V.Rao MD 27
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26. Morphology of Nocardia
–The Nocardia are branched, strictly
aerobic, Gram-positive bacteria that
are closely related to the rapidly
growing mycobacteria. Like the latter,
but unlike Actinomyctes, they are
environmental saprophytes with a
broad temperature range of growth. .
Most isolates are acid-fast when
decolorized with 1% sulphuric acid.
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27. Epidemiology
• Many species of Nocardia are found in the
environment, notably in soil, and a range of
species cause human opportunist disease,
notably Nocardia asteroids, so named because
of its star-shaped colonies, N, abscessus, N.
farcinica, N. brasiliensis, N. brevicatena, N.
otitidiscaviarum, N. nova and N. transvalensis.
A wider range of species is encountered in
profoundly immunosuppressed patients.
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28. Other Species Infective
• Nocardiae, principally N. asteroides, are
uncommon causes of opportunist pulmonary
disease, which usually, but not always, occurs
in immunocompromised individuals, including
those receiving post-transplant
immunosuppressive therapy or chemotherapy
for cancer and those with acquired immune
deficiency syndrome (AIDS).
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29. Nocardia and Corticosteroid Therapy
• Corticosteroid therapy is a strong risk factor.
As a result, the frequency and diversity of
clinical manifestations of Nocardia disease has
increased over the past few decades. Pre-
existing lung disease, notably alveolar
proteinosis, also predisposes to nocardial
disease. The infection is exogenous, resulting
from inhalation of the bacilli. The clinical and
radiological features are very variable and
non-specific, and diagnosis is not easy
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30. Clinical presentation
• Most cases there are multiple confluent
abscesses with little or no surrounding
fibrous reaction, and local spread may
result in pleural effusions, empyema and
invasion of bones. In some cases the
disease is chronic, whereas in others it
spreads rapidly through the lungs.
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31. Other Complications
• Secondary abscesses in the brain and, less
frequently, in other organs occur in about one-
third of patients with pulmonary nocardiosis.
Acute dissemination with involvement of
many organs occurs in profoundly
immunosuppressed persons, notably those
with AIDS. Recurrence is common in
immunosuppressed patients and mortality is
high.
Dr.T.V.Rao MD 33
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32. Other Complications
• Nocardiae also cause primary post-traumatic,
postoperative or post-inoculation cutaneous
infections (primary cuteneous nocardiasis).
The most frequent cause is N. brasiliensis but
some cases are caused by N. asteroides or
other species. In the USA and the southern
hemisphere, but rarely in Europe, cutaneous
infections may result in fungating tumour-like
masses termed mycetomas.
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33. Diagnosis of Nocardia Infections
• A presumptive diagnosis of pulmonary
nocardiasis may be made by a microscopical
examination of sputum. In many cases the
sputum contains numerous lymphocytes and
macrophages, some of which contain
pleomorphic Gram-positive and weakly acid-
fast bacilli, and occasional extracellular
branching filaments.
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34. Modified Z N Staining
• Nocardia are not so
easily seen in tissue
biopsies stained by the
Gram or modified Ziehl-
Neelsen methods, but
may be seen in
preparations stained by
the Gram-Weigert or
Gomori methenamine
silver methods.
Dr.T.V.Rao MD 36
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35. Culturing Nocardia
• Nocardiae grow on blood agar,
although growth is better on
enriched media including
Löwenstein-Jensen medium, brain-
heart infusion agar and Sabouraud's
dextrose agar containing
chloramphenicol as a selective agent.
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36. Culture on Media
• Growth is visible after
incubation for between
2 days and 1 month;
selective growth is
favoured by incubation
at 45°C. Colonies are
cream, orange or pink
coloured; their surfaces
may develop a dry,
chalky appearance, and
they adhere firmly to
the medium
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37. Treating Nocardia
• Widely used regimen is
sulfamethoxazole with trimethoprim
(co-trimoxazole) for 3-6 months,
although this prolonged course often
causes adverse drug reactions. In
addition, some strains, especially of
N. farcinica, are resistant to
sulphonamides.
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38. Other drugs in Use
• An alternative regimen, particularly
in severe disease, is high-dose
imipenem with amikacin for 4-6
weeks. Minocycline, third generation
cephalosporins, amoxicillin-
clavulanate combinations and
linezolid, an oxazolidinone, are also
effective. Dr.T.V.Rao MD 40
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