AFB Flashcards
Liquifcation
Step #1
NALC
Decontamination
Step #2
NaOH and Oxalic acid
Neautralization
Step #3
Buffer or Water
Centrifugation
Step #4
3000g x 15-20 minutes
Acid Fast
Org is surrounded by mycolic acid layer (hydrocarbons and wax)
Gram Stain does not penetrate wax = ACID FAST
Carbol Fuschion
Zich-Neelson: hot (heat removes wax)
Kinyoun: cold (pheynol removes wax)
Runyoun Group I
Photochromogens
Yellow pigment when exposed to light
(M. kanasii, M. marinum, M. simiae)
Runyoun Group II
Schotochromagens
Pigmented WITHOUT light, gets darker when exposed to light
(M. scrofulaceum, M. gordonae, M. Szulgi, M. Flavescens, M.xenopi, M. thermoresistible)
Runyoun Group III
Nonphotochromogens
non-pigmented
(M. avium-intercellulare, M. ulcerans, M.tb, haemophilum, gasti, terrae)
Runyoun Group IV
Rapid Growers
Grow is <7 days
M. fortuitum, M. chelonae, abscessus, smegmatis
Mycobacterium tuberclosis
Niacin + Nitrate + Urease + Catalase - Tween 80 Hyrdolysis -
Virulence: Antigen 85 Complex: “walls off” Mtb, high lipid content, grows intracellularly (inhibits phaygocytosis)
ID: PPD, Quantiferon (if infected, patient WBCs release IFN-gamma and amount of IFN-gamma is measured)
TX: Isonaizid, rifampin
Mycobacterium bovis
TB in cattle, cats, dogs, swine
Niacin (variable) Nitrate - Catalase - Urease + Tween 80 Hydrolysis -
Mycobacterium avium complex
Pulmonary disease similar to TB (cough, fatigue, fever)
lymphadenitis
Immunocompromised patients, AIDS
Affects bowels of AIDS patients
Niacin - Nitrate - Catalase- Urease - Tween 80 Hydrolysis-
Mycobacterium kansasii
Pulmonary disease (TX, LA, , FL, CA)
Chronic Cavitary Disease
Infects upper lung lobes with cavitation and scarring
AIDS/immunocompromised
Mycobacterium asiaticum
Rarely a pathogen
Mycobacterium gastri
Rarely a pathogen
Mycobacterium gordonae
Found in tap water and soil
Found often, but not always a pathogen (contam)
Niacin - Nitrate - Catalase + Urease- Tween 80 Hydrolysis +
Mycobacterium haemophilum
Patients with AIDS and Hodgkin’s Disease
Associated with painful swellings, abscessed, subcutaneous nodules
Needs hemoglobin or hemin for growth (CHOC)
grows better at 30 degrees Niacin- Nitrate - Tween 80 - Catalase -
Mycobacterium marinum
Associated with fish/aquariums
Cutaneous infections in humans after contact with water (lesions in life guards; “swimming pool granuloma”)
Grows better at 30
Mycobacterium scrofulaceum
cervical lymphadenitis in KIDS “ scrofula” (enlarged nodes in neck)
Treated with drainage, no anti-TB drugs needed
Mycobacterium szulgi
Pulmonary disease
Mycobacterium terrae Complex
Septic arthritis, synovitis, osteomyelitis
Mycobacterium ulcerans
Painless nodules under the skin, ulcer
Grows better at 32
Niacin - Nitrate - Catalase + Urease (variable) Tween 80 Hydrolysis -
Mycobacterium xenopi
Only seen in Southeast England
Lung infections in people with pre-existing conditions (alcoholism,lung disease, diabetes)
Mycobacterium chelonae
Found in the environment
Infections in immunocompromised patients
Mycobacterium fortuitum
From soil, water, dust
Skin and soft tissue infections
Associated with infections from long-term use catheters, surgical wounds, injection sites
Mtb Stage 1
Droplet nuclei inhaled
Mtb Stage 2
Engulfed by macrophages 7-21 days after incubation
Mtb Stage 3
T cells activated, releasing cytokines
Skin Test +
Tubercules form (“cheesy necrosis”)
Mtb Stage 4
Mtb replicates
Tubercules grow/spread outside lung (extra-pulmonary TB/Military TB…. brain, liver, kidney)
Mtb Stage 5
Center of tubercules liquifies
Bronchi rupture and form cavity
Lesions calcify = “Ghon Complex”
Mycobacterium leprae
Leprosy, Hansen’s Disease
US reservoir = 9-banded armadillo
Grows better at 30 degrees
Disease: loss of eyebrows, lesions, ticketed ears/cheeks
Grows better at lower temps (28-32)
Ulcerans
Marinum
Haemophilum
Chelonei
Grows better at higher temps (42-45)
Xenopi
Thermoresistible
PANTA
polymixin B, amphotericin B, naladixic acid, trimethoprim, azlocillin
Treatment for NTM infections
Rifampin, Ethambutol, Azithromycin
Nocardia
Soil organisms
Usually affect immunocompromised
No toxins, no virulence factors identified
Pulmonary and cutaneous infections
Branching GPB, beading
partial acid fast positive
might grow better using “paraffin bait technique”
Nocardia asteroides
pulmonary infections
Nocardia brasiliensis
cutaneous infections
thorns or slivers after outdoor activity