Actinomycetes and Nocardia

1. DR ARUNA RANI BEHERA
DEPARTMENT OF MICROBIOLOGY

2.  Actinomycetes are thin bacteria that possess a
cell wall containing muramic acid
 They have prokaryotic nuclei and are susceptible
to antibiotics
 Superficially resemble fungi due to branching
filaments
 Gram-positive, non-motile, non-sporing,
noncapsulated filaments that break into bacillary
or coccoid elements.
 Most are free-living in soil

4.  Anaerobic Actinomyces: Non-acid fast,
anaerobic or microaerophilic
-Arachnia, Bifidobacterium and Rothia
 Aerobic Nocardia: Aerobic, weakly acid fast
-Nocardia, Actinomadura, Dermatophilus and
Streptomyces
-Streptomyces may cause disease but they
are a major source of antibiotics

5.  Ray-like appearance of organisms in granules
 Chronic granulomatous infection in humans
and animals
 Indurated swelling, mainly in connective
tissues, with suppuration, discharge from
multiple sinuses
 Discharge has yellowish, soft, waxy granules
called sulphur granules
 Endogenous infection
 Trauma, foreign body and poor oral hygiene
may favour tissue invasion

6.  Actinomyces israelii is the most common
causative agent of actinomycosis
 Four main clinical types are seen
◦ Cervicofacial
◦ Thoracic
◦ Abdominal
◦ Pelvic

7.  Cervicofacial
actinomycosis:
- Most common form
- Painless, slow-
growing, hard mass
with cutaneous
fistulas  lumpy jaw
- Indurated lesion on
the cheek and
submaxillary region

9. ◦ Thoracic: Lesions in the lung, may involve the pleura and
pericardium, spreading outwards through the chest wall
◦ Abdominal: Lesion is usually around the cecum, involving
neighbouring tissues and abdominal wall
◦ Pelvic: Associated with the use of intrauterine device (IUD),
abscess in bone and soft tissues with chronic draining
sinuses to the exterior
 Causes disease of gums( gingivitis,
periodontitis )and sublingual plaques leading
to root surface caries
 May present as mycetoma, treated with
penicillin for several weeks

10. 1.Specimens- pus or tissues
- pulmonary disease- sputum
2. Gross examination of granules-
 Pus washed in saline & sediment collected – Sulfur
Granules: gritty, white or yellowish of <5 mm in
size
 Granules crushed between two slides  smears
(white to yellow)
3.Direct microscopy: Dense network of thin Gram-
positive filaments surrounded by peripheral zone
of swollen, radiating, club-shaped structures
presenting a sun ray appearance; the clubs are
antigen–antibody complexes

12. 4.Isolation in culture: Sulphur granules or pus
innoculated into thioglycollate liquid medium or
streaked on brain–heart infusion agar
 Washed sulfur granules cultured anaerobically at
37°C
 Thioglycollate broth:
- A.israelii - fluffy balls at the bottom of the tube
- A.bovis - uniform turbidity
 ™
Brain heart infusion (BHI) agar: Small spidery
colonies in 48–72 hours, becomes heaped up,
white, irregular smooth large colonies in 10 days

13.  Penicillin, tetracycline for months supplemented
with surgery

15.  Resembles Actinomycetes morphologically
but it is aerobic
 Nocardia are Gram-positive and some
species like N. asteroides and N. brasiliensis
are acid fast
 Found in soil and infection is exogenous
 Causes cutaneous, subcutaneous and
systemic lesions
 Common species are N. asteroides,
N. brasiliensis and N. caviae

16. Morphology:
 Filamentous, rod-shaped bacteria that do not
produce spores, non-motile, catalase positive
and weakly acid fast by Kinyoun’s acid fast
staining method
 N. asteroides is most commonly involved in
human disease
 Transmission is through contaminated soil
and not from humans or animals

17. • Clinical forms:
–Cutaneous: Local abscess, cellulitis or
lymphocutaneous lesions, subcutaneous
actinomycotic mycetoma
–Systemic: Manifests as pulmonary disease,
pneumonia, lung abscess or resembles
tuberculosis
–Metastatic manifestation: May involve the
brain, kidneys and other organs
Systemic nocardiosis occurs more often in
immunodeficient persons

18. 1.Direct microscopy
Modified acid-fast
staining( 1% sulfuric
acid)
- Nocardiae are weakly
acid fast
- Branching &
filamentous acid-fast
bacilli

19. 2.Isolation in culture: Grows on ordinary media
forming dry, granular wrinkled colonies,
producing pigment ranging from yellow to red
Treatment:
Resistant to penicillin; cotimoxazole and
minocycline are used
◦ Surgery is performed to remove mycetomas
◦ In immunocompromised, amikacin and cefotaxime are
used

20.  Usually caused by
◦ Actinomyces israelii, A. bovis
◦ N. asteroides, N. brasiliensis, N. caviae
◦ Actinomadura madurae, A. pelletierii
◦ Streptomyces somaliensis
 Botryomycosis: Mycetoma-like lesion
produced by Staphylococcus aureus and
other pyogenic bacteria

21.  Mycetoma is a localised chronic granulomatous
involvement of subcutaneous and deeper
tissues affecting the foot and hand and
presenting as swelling with multiple
discharging sinuses
 First described by Gill 1842— maduramycosis
 Actinomycotic – granules are yellow or white,
filaments are thin (1 µm)
 May be due to fungus, filaments are thicker
(4–5 µm), granules are black

22.  Allergic alveolitis, hypersensitive
pneumonitis and chronic pulmonary
obstructive disease (COPD)
 May be caused by inhaled spores of
thermophilic actinomycetes

23. Actinomyces Nocardia
Acid-fastness Non Acid fast Partially acid fast
O2 requirement Anaerobe Obligate aerobe
Habitat Found as oral flora
Infections occur
endogenously
Usual habitat is soil
Infections occur
exogenously
Risk factors Disease occurs in
immunocompetent host
also
Usually affects
people with low
immunity

24. Actinomyces Nocardia
Culture 1.Spidery molar teeth
colony in solid media
2.Fluffy ball at
bottom of the liquid
medium
Colonies are creamy,
wrinkled and orange
to pink.
Recovery done by-
1.Selective media
2.Paraffin bait
technique
3.LJ medium
Drug of choice Penicillin Sulfonamide or
Cotrimoxazole