Bacte - Lesson 18: Branching. Aerobic, Partially Acid Fast & Non-Acid Fast Gram (+) Bacilli

1. nocardia

2. rhodococcus

3. gordonia

4. tsukamurella

actinomycetes (acid fast):

actinomycetes

large and diverse group of gram (+) bacilli; cells elongate to form branching

1. strain

2. growth medium

3. temperature of incubation

rate and extent of filament elongation w/ lateral branching of actinomycetes (acid fast) depends on:

1. substrate hyphae

2. aerial hyphae

2 types of temperature of incubation:

substrate hyphae

forming of filaments/hyphae on agar surface or into agar

aerial hyphae

hyphae extends to air

nocardia

N inhabitants of soil & water; for decomposition of plant materials

nocardia

ubiquitous; isolation from clinical spx does not indicate infection d/t ability of getting rid of it in healthy indivs

nocardia

isolation may be d/t colonization of skin and URT or lab contamination

1. traumatic inoculation

2. inhalation

nocardia MOT:

nocardia

beaded appearance; catalase (+); strictly aerobic

nocardia

as they age, fragments into pleomorphic rods or coccoid elements

nocardia

presence of mesodiaminopimelic acid (DAP)

nocardia

presence of sugars arabinose and galactose in peptidoglycan in cell wall

1. mycetoma

2. lymphocutaneous infections

3. skin abscess/cellulitis

3 types of skin infections:"

pulmonary infection

farmer’s lung; inhalation of organism from dust or soil; manifestation: bronchopneumonia

pulmonary infection

no sulfur granules or sinus tract formation

pulmonary infection

no special req for specimen collection, transport, and processing; able to grow on routine lab media

1. BAP

2. CAP

3. saboraud dextrose agar

4. brain heart infusion agar

routine lab media for nocardia/farmer’s lung:

nocardia

slow grower; 48-72h before colonies are visible

1. asteroides

2. nova

3. farcinica

4. brasiliensis

5. otitidiscaviarum

6. pseudobrasiliensis

nocardia (human pathogens):

tsukamurella

similar to nocardia; differentiation and identification w/ rhodococcus and gordonia is difficult

1. amount

2. complexity of mycolic acid on cell envelope and culture conditions

extent of acid fastness of tsukamurella depends on:

1. farm animals

2. fresh & salt water

tsukamurella isolated from:

inhalation

tsukamurella MOT

rhodococcus equi

gram (+) bacilli; assoc w/ human illness in immunocompromised px (HIV)

rhodococcus equi

facultative intracellular organisms that persist and replicate w/in macrophages

rhodococcus equi

virulence still under investigation

1. intracellular survival

2. IL-4

3. granuloma formation

tsukamurella virulence may involve mycolic acid that may play role in:

1. streptomyces

2. actinomadura

3. dermatophilus

4. nocardiopsis

5. thermophilic actinomycetes

actinomycetes (non-acid fast):

1. thermoactinomycetes

2. saccharomonospora

3. saccharopolyspora

thermophilic actinomycetes:

thermophilic actinomycetes

encountered infrequently in clinical lab; assoc w/ immunocompromised status

thermophilic actinomycetes

infection assoc w/ mycetoma (chronic granulomatous lesion of skin)

mycetoma

infection of subcutaneous tx that results in tissue swelling and drainage of sinus tracts

mycetoma

acquired by traumatic inoculation of organism (usually in lower limb) caused by fungi

thermophilic actinomycetes

responsible for hypersensitivity pneumonitis; occupational disease in farmers, factory workers

actinomycetoma

non-fungi; caused by actinomycete

actinomycetes

identification is beyond capability of routine clinical lab; referred to reference labs; no vaccines; avoid exposure