Actinomycetes (Micro Exam 3)

Misc. pathogens

1. Legionella sp.--Legionnaires' disease 2. Bartonella sp. --Cat scratch disease/other 3. Eikenella corrodens--Human bite wound

Actinomycetes

1. large group= characteristics of bacteria and fungi 2. form branches or filaments=hyphae 3. infections resemble fungal diseases 4. bacterial=procaryotic cell wall 5. susceptible to penicillin like bacteria

Actinomycetes functions and characteristics

1.form of fungi-like bacteria 2. sometimes called thread bacteria 3. in composting, they give off an earthy smell 4. primary decomposers of woody stems, newpapers, and bark 5. are very common in the soil at a rate of 1/4 pound per cubic foot in healthy soil especially higher pH soil (alkaline) and drier soils 6. comprises 5% of soil's total population

Actinomycosis

Actinomyces israelii and others

______ is the primary source of antibiotics used in topical antibiotic creams

Actinomycetes

B. henselae

Cat Scratch Disease -scratches, bites, cat fleas -chronic regional swelling of lymph nodes -culture often negative -view organism on tissue sections -antibiotics=often not used; tetracycline, erythromycin, rifampin

Nocardiosis

Nocardia asteroides and others

Actinomycosis diagnosis

-examine pus for white or yellow granules -Gram stain (+) -filamentous -culture -immunofluorescence

Actinomycosis genital

-intrauterine devices=inflammation

Legionella Epidemiology

-located in fresh water -attach to pipes, rubber, plastics -avoid chlorination-gobbled by amoeba -aerosols=human-human not shown -70% predisposed=underlying illness, older, heavy smoker

Nocardiosis diagnosis

-microscopic appearance=granules, filaments -grow on appropriate medium= 7-10 days. -Gram +, acid-fast organism -biochemical tests (casein hydrolysis +, urea hydrolysis +, tyrosine hydrolysis +)

Actinomycosis cervicofacial

-most common -lower jaw=abscess formation -sinus tracts that reach the skin

Legionella

-respiratory disease -difficult to isolate -CDC identified the organism

Nocardiosis treatment

-surgical debridement -early diagnosis important-poor recovery after systemic infection -treat with cotrimazole or sulfadiazine -respiratory infections may require several months

Actinomycosis treatment

-surgical debridement of damaged tissue is a pre-requisite to antibiotic therapy -Penicillin G for 3-4 weeks= treatment of choice -Trimethoprim and sulfamethoxazole result in more rapid cure

Those at risk for nocardiosis:

-weakened immune system -chronic lung disease -chronic steroid therapy -cancer -organ/bone marrow transplants -HIV/AIDS

______ is the most numerous of all actinomycetes

Streptomyces

Sugar consumption=...

acid production which erodes the enamel surface = dental carie

periodontitis

destruction of the bone that supports teeth

If plaque not removed...

inflammation of the gums=gingivitis

Actinomycetes are Gram ____

positive

How do A. viscosus organisms attach to enamel surface?

production of pili and extracellular polysaccharides (sticky)

Actinomycosis abdominal

trauma of intestine or abdominal wall

Eikenella

-E. corrodens -most frequently isolated -human bite wounds or fist fight injuries -may lead to sinusitis, brain abscess, pneumonia, endocarditis -slow growing, fastidious organism that "corrodes" the agar -opportunist

Legionella pneumophila

-Gram -, aerobic bacillus -Facultative intracellular parasite -produces a cytotoxin

Actinomycosis thoracic

-aspiration into lung -extension of cervicofacial -hematogenous

Nocardia asteroides

-compromised patients -steroid administration= patient more susceptible -inhalation or introduction to traumatized tissue -see nodular abscesses -in skin and soft tissue= see sinuses and granules -as sinus tracts extend to deep muscle and bone=actinomycetoma

Legionella diagnosis

-culture from sputum or lung specimen on BYCE agar -use direct fluorescent antibody test/moderate sens -use indirect fluorescent antibody test=4-fold rise, not very useful early in disease -Radioimmunoassay=detect AG in urine, 86%

Bartonella

-8 species -short, Gram- bacilli -aerobic -fastidious growth requirements -animal reservoirs/insect vectors

Dental plaque

-Actinomyces viscosus -organisms attach to enamel surface

Actinomycosis

-Cervicofacial -Thoracic -Abdominal -Genital