Nocardia are aerobic, gram-positive bacteria that are ubiquitous environmental saprophytes found in soil. They cause opportunistic infections in both immunocompromised and immunocompetent individuals. Nocardia infections can manifest as cutaneous disease, pulmonary disease, disseminated disease, or central nervous system infections such as brain abscesses. Diagnosis involves microscopic examination of samples showing branching filaments, culture growth on selective media, and molecular techniques such as PCR and 16S rRNA sequencing. Treatment involves prolonged courses of antibiotics such as trimethoprim-sulfamethoxazole or amikacin depending on the species.

1. Nocardia
By
Jagrity singh
M.Sc 3rd sem

2. Classification
• Kingdom:Bacteria
• Phylum:Actinobacteria
• Class:Actinobacteria
• Order:Actinomycetales
• Suborder:Corynebacterineae
• Family:Nocardiaceae
• Genus:Nocardia

3. Introduction
• Named after Edmond Nocard, in 1888 described the
organism in cattle with bovine farcy.
• First human case of nocardiosis was reported in 1890 by
Eppinger.
• Members of the genus Nocardia are associated with the
group of microorganisms known as the aerobic
actinomycetes and belong specifically to the
family Mycobacteriaceae. The nocardiae contain
tuberculostearic acids but differ from the mycobacteria by
possession of shorter-chained (40- to 60-carbon) mycolic
acids.
• They have a type IV cell wall, characterized by a
peptidoglycan made up of meso-diaminopimelic acid,
arabinose, and galactose

4. Habitat
• Ubiquitous environmental saprophyte Soil,
organic matter, water Tropical and subtropical
regions.

5. Nocardia is present as commensal In
Humans
Nocardia are found
worldwide in soil that is
rich with organic matter.
In addition, Nocardia are
oral microflora found in
healthy gingiva as well as
periodontal pockets.
Most Nocardia infections
are acquired by inhalation
of the bacteria or through
traumatic introduction.

6. Other Species of Nocardia
• Gram-positive bacteria.
• On microscopy have branching filamentous
cells. The more common human pathogen are
Nocardia asteroids sensu stricto,
Nocardia farcinica, Nocardia nova,
Nocardia brasiliensis,
Nocardia pseudobrasiliensis,
Nocardia otitidiscaviarum, and
Nocardia transvalensis

7. Morphology
• Nocardia sp. are aerobic, gram-
positive bacteria which are
filamentous, relatively slow growing,
and variably acid fast.
•Branching, beaded, filamentous
bacteria and non motile
• Can cause "Sulfur granules" like
actinomycosis, in nocardial
mycetomas.
• Stains acid fast in tissue unlike the
Actinomyces.

8. Culture character
• Plate culture of the bacteria Nocardia asteroides
grown on 7H10 agar plates at 37° C.
• Media: Nutrient agar, sabouraur agar, brain heart in
fusion agar, yeast extract malt extract agar.
• Specimens with mixed flora can over grow the
Nocardia colonies
• Selective media may increase yield:
– Thayer-Martin agar with antibiotics
– paraffin agar.
– Buffered charcoal-yeast extract (BCYE) medium

9. Culture…..
• Norcardia forms white or yellow or pink brown
colonies.
• N. madurae – leathery colonies with red pigment
• N. asteroides – star shaped colony
• Colonies are formed after 3 weeks of incubation
at 36oc
• On LJ medium after 1-2 weeks of incubation,
colonies resemble saprophytic mycobacteria
(some are white, some are pigmented)

10. Biochemical characters
• Usually not necessary to identify Nocardia spp
• Casein hydrolysis test can be done to
differentiate N. asteroides from N. brasiliensis
• N. asteriodes doesnot hydrolyse casein
• N. brasiliensis – hydrolyse casein
• Both N. asteroides and N. brasiliensis are
urease positive.

14. Virulence Factors
• Virulent strains are relatively resistant to
neutrophil mediated killing.
• Organisms in the logarithmic growth phase are
more toxic to macrophages.
• Inhibit Phagosome-lysosome fusion more
successfully in vitro, which gives rise to L-forms,
which can survive in macrophages for days
• L-forms have been found human and animal
infections and perhaps account for treatment
failure.

15. Virulence factors
• The inability to be killed by normal white cells takes on
additional significance in the immunoincompetant who
have WBC dysfunction that tips the battle between
host and pathogen in favor of the Nocardia.
• Patients with CGD have increased risk for Nocardia
infections, a double whammy where the patients
cannot generate an oxidative burst and some strains
have the ability to make superoxide dismutase.

16. Species tissue tropism's
– N. asteroides complex including N. farcinica cause
80% of noncutaneous invasive disease and for most
systemic and CNS disease.
– N. brasiliensis: cutaneous and lymphocutaneous
disease.
– N. pseudobrasiliensis: systemic infections, including
the CNS.
– N. transvalensis and N. otitidiscavarium: Noncutaneous
disease

17. Clinical presentation of Nocardia
• Overall, 80% of nocardiosis cases present as invasive pulmonary
infection, disseminated infection, or brain abscess, 20% present as
cellulitis.
• Lymphocutaneous syndrome
• Pulmonary :Pneumonia
• CNS : Brain abscess
• Disseminated disease
CNS
Eyes (particularly the retina Keratitis),
Skin& subcutaneous
Kidneys,
Joints, bone
Heart

18. Clinical Syndromes: Mucocutaneous
• Mycetoma: a chronic progressive, destructive
disease, occurring days to months after inoculation
• located distally on the limbs (classically the foot)
and presents with
– Suppurative granulomata
– progressive fibrosis and necrosis
– sinus formation and destruction of adjacent
structures,
– macroscopically visible infective granules
– Mimics fungal mycetoma and actinomycetomata
(due to actinomycete).

20. Pulmonary
Clinical Presentations:
– endobronchial inflammatory masses pneumonia
– lung abscess,
– cavitary disease
– empyema
– pneumonia (often progressive in HIV)
– it can invade through surrounding tissues like
actinomycosis

21. Pulmonary disease
Pneumonia
Subacute(more acute in immunosuppressed)
Cough**
Small amounts of thick, purulent sputum
Fever, anorexia, weight loss, malaise
• Endobronchial inflammatory mass
• Lung abscess
• Cavitary disease
• Inadequate therapy =Progressive fibrotic disease
• Cerebral imaging, should be performed in all cases of
pulmonary and disseminated nocardiosis

22. CNS : Brain abscess
Insidious presentations : mistaken for neoplasia !!!
• Granulomatous , abscesses
• Cerebral cortex, basal ganglia and midbrain
• Less commonly: spinal cord or meninges.
• However, cerebral biopsy: considered early in
immunocompromised

23. LABORATORY DIAGNOSIS
• Specimens: Sputum, CSF, blood, Tissue, pus or exudate
with granules, body sites with an abscess condition,
Bronchial washings, bronchial lavage fluids
• Transport/Storage:
• Onsite collections: Transport specimens to the
laboratory immediately.
• Offsite collections: Refrigerate specimen. Specimens
must be promptly transported to the laboratory, not to
exceed 24 hours from the time of collection. However,
delayed transport causes a delay of test results.
• Special Processing: Store at 4°C until specimen can be
shipped. Ship within 24 hours.

24. Diagnosis
• Macroscopic examination: The initial macroscopic inspection should
include examination for the presence or absence of granules, and if
granules are present, they should be carefully washed in sterile
saline, crushed, and examined microscopically. These granules are
most often seen in infections with N. brasiliensis but also can be
produced by other Nocardia species and with Actinomyces species
• Microscopic examination: Gram sataining = gram-positive, thin,
branching, filamentous organisms, usually in a background of
purulence with many polymorphonuclear leukocytes.
• 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.

25. • With the modified Kinyoun acid-fast stain using
weak acid (1% sulfuric acid) for decolorization,
the nocardiae are often seen as partially acid-fast
filamentous bacilli (showing both acid-fast and
non-acid-fast organisms).
• Histologically, Nocardia has delicate (< 2 microns
in thickness) filaments with pronounced
branching.

26. Culture
• Nocardiae grow on blood agar, although growth is
better on enriched media including Löwenstein-Jensen
medium, brainheart infusion agar and Sabouraud's
dextrose agar containing chloramphenicol as a
selective agent.
• 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
• On tap-water agar, Nocardia species have recursively
branching hyphae with aerial hyphae.

27. Biochemical test
• hydrolysis of casein, tyrosine, and/or xanthine, (2) presence of
urease, (3) utilization of rhamnose, and (4) positive resistance to
lysozyme.
Table 1: Hydrolysis Tests for differentiating Nocardia strain
Casein hydrolysis L-tyrosine hydrolysis Xanthine hydrolysis
N. asteroides complex,
N. farcinica, or N. nova - - -
N. brasiliensis
+ + -
N. otitidis
- + -
N. caviae
- - +
Streptomyces or
Nocardiopsis + + +

28. Chemotaxonomic methods
• Whole-cell hydrolysates examined for the presence of meso-
diaminopimelic acid and specific carbohydrates are useful tools in
the identification of the nocardiae in laboratories that can
perform these tests.
• Evaluation of the chromatographic patterns of p-bromophenacyl
esters of mycolic acids by HPLC may be helpful in identifying
isolates resembling Nocardia to the genus level.
• However, most species of the nocardiae show similar mycolic acid
patterns by HPLC and are difficult, if not impossible, to
characterize to species.
• Gas-liquid chromatography of the short-chain fatty acids has also
been used for identification of Nocardia

29. Serology
• Immunodiffusion techniques to detect circulating
antibodies
• Complement fixation test were also shown to be
nonspecific but were able to detect antibodies in most
of the serum samples tested from
immunocompromised patients
• Immunoblot and enzyme-linked immunosorbent assays
which detect antibodies to specific high-molecular-
weight proteins that appear to be common in
various Nocardia and Actinomadura species have been
developed. These antigens do not react with antibodies
produced in response to Mycobacterium
tuberculosis infections

30. Molecular technology
• PCR83,84 and 16S rRNA sequencing are the
most reliable for giving a precise spp.
• DNA probe
• DNA sequencing
• Pyrosequencing
• Ribotyping
• Direct detection in paraffin-embedded tissue
and clinical samples

31. Antibiotic Resistance
of N.asteroides group members
Tobramycin Cefamandole or
Cefotaxime
Erythromycin
N. asteroides complex Variable Resistance Sensitive Resistant
N. farcinica Resistant Resistant Resistant
N. nova Resistant Sensitive Sensitive

32. • http://cmr.asm.org/content/19/2/259/T3.exp
ansion.html