Actinomycetes are filamentous, gram-positive bacteria that can cause infections in humans. Three types of infections are discussed: 1. Actinomycosis is caused by Actinomyces bacteria, most commonly A. israelii. It presents as a chronic infection forming lumps with draining sinuses. Diagnosis involves identifying the bacteria in pus or a "sulphur granule". Penicillin is the treatment. 2. Nocardiosis is caused by aerobic, weakly acid-fast Nocardia bacteria found in soil. It can cause pulmonary or disseminated infections. Diagnosis involves identifying filamentous bacteria in samples. Cotrimoxazole

1. Dr. Vaishali
Post Graduate
Department of
microbiology
ACTINOMYCETES
INFECTIONS

2. ACTINOMYCETES
Actinomycetes are 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 filaments may break into
bacillary or coccoid elements, non-motile,
non-sporing, non-capsulated
Most are free-living in soil

3.  Gram-positive arranged in chains or branching filaments
 Nonmotile, non-sporing, non-capsulated bacilli
 True bacteria resembling fungi, form mycelial network of
branching filaments
 Soil saprophytes or normal human commensals
ACTINOMYCETES INFECTIONS

4.  Actinomyces: Anaerobe and non-acid-fast; produce a clinical
condition called actinomycosis
 Nocardia: Aerobe and acid-fast ; cause actinomycetoma and
pulmonary infection
 Actinomadura: Aerobe and non-acid fast; cause
actinomadurosis
CONT…

5.  Streptomyces: Aerobe and non-acid-fast; rarely cause
actinomycetoma in man - also remain as an important source
of antibiotics - streptomycin
 Thermophilic actinomycetes – Micropolyspora and
Thermoactinomyces - cause hypersensitivity pneumonitis
(farmer’s lung and bagassosis).
CONT…

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

8. ACTINOMYCES (RAY FUNGUS)
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
Trauma, foreign body and poor oral hygiene
may favour tissue invasion

9.  Actinomyces - soil saprophytes and commensals of oral cavity.
 In humans, they cause actinomycosis.
 A. israelii - most common species infecting man.
ACTINOMYCOSIS

10.  Chronic suppurative and granulomatous infection - multiple
discharging sinuses, granules  fibrosis and tissue
destruction
 Mode of infection: Endogenous and result from trauma, e.g.
dental extraction
 Grow in oral anaerobic niche  induce a mixed inflammatory
response  painless indurated swelling with sinuses  drain
pus containing granules
 Spread to neighboring organs including the bones  tissue
destruction
PATHOGENESIS

11. ACTINOMYCOSIS
Four main clinical types are seen
 Cervicofacial: Indurated lesion on the cheek and
submaxillary region
 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

12.  Cervicofacial
actinomycosis:
Most common form
Painless, slow-growing,
hard mass with cutaneous
fistulas  lumpy jaw
CLINICAL MANIFESTATIONS
A B

13.  Abdominal form: Due to spillage of intestinal flora secondary
to bowel surgery or appendicitis
 Pelvic form: Following intrauterine contraceptive devices
(IUCDs) insertion
 Brain abscesses
 Bone destruction and soft tissue infections
 Disseminated form: Hematogenous spread (Lungs & liver) -
Nodules
 Dental caries and periodontal diseases
CONT..,

14.  Causes disease of gums, gingivitis, periodontitis and
sublingual plaques leading to root surface caries.
 May present as mycetoma, treated with penicillin for
several weeks

15. LABORATORY DIAGNOSIS OF
ACTINOMYCOSIS
 Specimen:
Discharge from the sinuses or fistula.
Sputum, bronchial washings, and cervico vaginal
secretions.
Sulphur granules are demonstrated in
pus

16.  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
Pus washed in saline & sediment collected – Sulfur
Granules: gritty, white or yellowish of <5 mm in size
Granules crushed between two slides  smears

17. Direct Microscopy (Cont..):
 Gram-staining (Brown–
Brenn modification):
Central Gram-positive
filamentous bacilli
Radiating peripherally
with hyaline, club-shaped
ends
A B C

18. LABORATORY DIAGNOSIS OF
ACTINOMYCOSIS
Fig 43.1

19. Direct Microscopy (Cont..):
 Histopathology
-Hematoxylin-eosin &
Gomori’s - Granules -
eosinophilic clubs,
surrounding basophilic
filaments and inflammatory
cells (sun-rays appearance)
C

20. Culture:
 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

21. LABORATORY DIAGNOSIS OF
ACTINOMYCOSIS
Isolation in culture: Sulphur granules or
pus innoculated into thioglycollate liquid
medium or streaked on brain–heart
infusion agar incubated anaerobically at
37°C
Liquid medium, A.israelii produces fluffy
ball colonies at the bottom
Solid medium, Actinomyces israelii
produces spidery colonies in 48–72 hours,
becomes heaped up, white, irregular
smooth large colonies in 10 days

22. Species Identification:
 Biochemical reactions
 Automated methods - MALDI-TOF
 Molecular methods - PCR detecting 16S-rRNA gene are also
available for speciation.

23.  Recommended regimen - IV ampicillin or IV penicillin G for 4–
6 weeks followed by oral penicillin V or amoxicillin for 6–12
months.
 Lesser duration - cause relapse
 Doxycycline, ceftriaxone or clindamycin - penicillin allergy
 Surgical removal of the affected tissues - required for
extensive lesions.
TREATMENT

24. NOCARDIOSIS

25. NOCARDIA
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

26. NOCARDIA
Morphology:
 Filaments, 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

27.  Gram-positive branching filamentous bacilli
 Aerobic and acid-fast
 Environmental
 Common pathogens – N.asteroides & N.brasiliensis
NOCARDIA

28.  Inhalation of fragmented bacterial filaments:  pulmonary
nocardiosis
 Transcutaneous inoculation of bacteria: Cutaneous and
subcutaneous manifestations (e.g. mycetoma).
 Person-to-person spread is not known.
PATHOLOGY AND PATHOGENESIS

29.  Cell-mediated immunity - important role in controlling the
disease.
 Tend to occur frequently in immunocompromised conditions -
AIDS, corticosteroid treatment, organ transplantation and
tuberculosis.
RISK FACTORS

30.  Pulmonary Nocardiosis:
Lobar pneumonia - subacute onset of cough with thick,
purulent sputum
Rarely spread to adjacent tissues  Pericarditis,
mediastinitis, laryngitis, tracheitis and bronchitis
CLINICAL FEATURES

31.  Extrapulmonary (Disseminated) Nocardiosis:
Haematogenous dissemination
Subacute abscess – Brain (MC), skin, kidneys, bone and
muscle, Meningitis is uncommon
CONT…

32. NOCARDIA
• 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

33.  Specimen:
Sputum, pus from abscess
Granules - collected in sterile gauze or loop by pressing
sinuses
LAB DIAGNOSIS

34.  Direct Microscopy:
Gram staining (Brown–Brenn modification):
Gram-positive branching and filamentous bacilli 0.5–1
μm thick
Histopathology (H and E stain) of the granules: Sun ray
appearance
CONT…

35.  Direct Microscopy (Cont..):
Modified acid-fast staining(
1% sulfuric acid)
Nocardiae are weakly acid
fast
Branching & filamentous
acid-fast bacilli

36.  Culture:
Obligate aerobes
Grow on brain heart infusion agar and Sabauraud dextrose
agar (SDA) - 2 days to 2 weeks
Colonies- Creamy, wrinkled, pigmented & adhere firmly
medium

37. Culture (Cont..):
 Recovery of Nocardia from the samples containing
Actinomadura and Streptomyces can be done by:
Using selective media
Paraffin bait technique
Lowenstein–Jensen medium

38. Culture (Cont..):
 Using selective media:
Buffered yeast extract containing polymyxin and
vancomycin

39. Culture (Cont..):
Paraffin bait technique: Paraffin as the sole carbon
source.
Lowenstein–Jensen medium: Produces moist glabrous
colonies (differentiates from mycobacteria).

40.  Identification:
Appropriate biochemical tests or automated methods
such as MALDI-TOF

41.  Cotrimoxazole - drug of choice for all forms of nocardiosis
 For severe disease - brain abscess or pneumonia,
cotrimoxazole plus imipenem is recommended
TREATMENT

42.  Duration of treatment
For severe disease: 6–12 months (for intact host defense) or
1 year (for deficient host defense)
For lymphadenitis, skin abscess: 2 months
For actinomycetoma: Until 6–12 months after cure
For keratitis: Until 2 months after cure
CONT…

43. Features 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
Clinical forms Cervicofacial,
abdominal and others
Pulmonary, CNS forms,
Actinomycetoma
DIFFERENCES BETWEEN
ACTINOMYCES AND NOCARDIA

44. Features Actinomyces Nocardia
Granules Sulfur granules are hard and not
emulsifiable, consist of branching
filamentous bacilli and
surrounded by clubs (sun-ray
appearance)
 Granules are soft and
lobulated and also show sun-
ray appearance
 Commonly found in
mycetoma, rare in other
conditions
Culture  Spidery molar teeth colony in
solid media
 Fluffy ball at bottom of the
liquid medium
Colonies are creamy, wrinkled
and pink
Isolation is done in:
 Selective media
 Paraffin bait technique
 LJ medium
Treatment Penicillin Cotrimoxazole
CONT…

45. ACTINOMYCOTIC MYCETOMA
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

46.  Actinomadura - most frequent cause of actinomycetoma.
 A. madurae and A. pellettieri - important species
 Granules - white to yellow except in case of A. pellettieri that
produces red colored granules.
 Colonies - molar tooth appearance after 48 hours in culture
with sparse aerial growth
ACTINOMADURA INFECTIONS

47. FARMER’S LUNG
Allergic alveolitis, hypersensitive
pneumonitis and chronic pulmonary
obstructive disease (COPD)
May be caused by inhaled spores of
thermophilic actinomycetes like Faenia
and Saccharomonosporia species

48. MYCETOMA FROM BACTERIAL
CAUSES
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

49. THANK YOU