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Vaccine and Treatments Key Identification Isolation technique Staining method Specimen Collection Transmittanc e and Personal safety Photochromo gens Scotochromo gens Rapid Growers Non- chromogens Leprosy
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Transmitted via: Airborne droplets (e.g. coughing ) In a confined space (e.g. jail, at home, school, work etc) General safety: Adequate ventilation; wear masks; early detection and treatment Lab safety: Use biosafety level 3 cabinets with directional airflow; aerosol free centrifuges; protective coverings, UV light; periodic TB testing, etc. Symptoms: Fatigue, weight loss, cough, fever, night sweats. X-ray illustrates cavitary disease of solitary nodules
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M. tuberculosis Rough, buff, about 21 days Key reactions: Niacin and Nitrate Confirmation: Nucleic acid probes or HPLC (high performance liquid chromatography). Mainly causes pulmonary illness but can be anywhere. M. avium-intracelluare (M.A.C) Rough or smooth, slow Can be other Runyoun groups Key reactions: lack of niacin and nitrate, growth in NAP and TCH. Semi-quant cat and tellurite are positive Pulmonary, disseminated M. bovis Generally smooth, buff colonies with irregular margins seen after 21 days of incubation at 37ºC. Key reactions: Urease positive, sensitive to TCH Causes pulmonary illness mainly in livestock but can be transmitted from cattle to humans.
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M. xenopi Recovered from water, hot and cold taps Can be scotochromogenic Small, slow growing colonies with dense centers and filamentous edges Optimum growth at 42 degrees Celsius Key reactions: Niacin negative, nitrate negative, Catalase positive, arylsulfatase positive, PZA positive Slow progressive pulmonary infection M. haemophilum Rough to smooth buff colonies Optimum growth at 28-32oC Requires heme/hemoglobin for growth Cause lymphadenitis, abscesses, draining fistulas (but mostly in immunocompromised patients) M. ulcerans Slow growth, buff smooth and rough colonies Optimum growth 30-33oC, 6-12 weeks incubation Key reactions: Biochemically inert Bairnsdale ulcer, cutaneous lesions in tropical regions following soil disturbances.
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M. kansasii Yellow carotene pigment when exposed to light Rough colonies with wavy edges and dark centers, slow growth at 37 degrees C Key reaction: Niacin negative, strongly positive for nitrate and catalase, PZA and Tween 80 positive Chronic pulmonary disease M. simiae Smooth, slow growing colonies, 10-21 days at 37 degrees C Key reactions : Niacin positive (can easily be mistake n for M. tuberculosis), Nitrate negative, catalase positive Pulmonary disease M. marinuum Optimum growth at 28oC-32oC Buff colonies seen in the dark, yellow when exposed to light Slow growing, smooth to rough colonies. Key reactions: Niacin and nitrate negative, catalase negative, PZA positive Cutaneous infections after trauma in water M. asiaticum Dysgenic and smooth Growth after 15 to 21 days at 37oC Key reactions: Niacin negative, Nitrate negative, Catalase positive, Tween 80 positive Rarely causes human infection
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M. gordonae Smooth yellow-orange colonies, 10-14 days Optimum temperature: 22-37oC Key reactions: Nitrate negative, catalase positive, Tween 80 positive, urea positive Rarely causes infection Contaminant from tap water (referred to as “tap- water bacillus”) M. szulgai Pigment production is temperature dependent Photochromogen at 22oC Smooth and rough colonies Key reactions: slow hydrolysis of Tween 80, nitrate positive, inability to grow in the presence of 5% NaCl Pulmonary disease M. scrofulaceum 4-6 weeks growth at 25-37 degrees Celsius Smooth light yellow to deep orange colonies with dense centers Key reactions: Nitrate negative, catalase positive, Tween 80 negative, urea positive Associated with cervical lymphadenitis in children
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M. fortuitum Growth in 3-5 days of incubation at 37oC Buff rough or smooth colonies Key reactions: Positive 3-day arylsulfatase test, nitrate positive, NaCl positive, iron positive Skin and soft tissue, “whirlpool footbath” infections M. chelonae Related to M. abscessus Most commonly isolated rapid grower Rough or smooth buff colonies Growth within 3-5 days of incubation at 37oC Key reactions: Positive 3-day arylsulfatase, nitrate negative, iron negative, NaCl negative Disseminated nodular disease in immunocompromised patients M. smegmatis complex Buff, rough, wrinkled or coarsely folded growth after 2-4 days Key reactions: negative arylsulfatase, iron positive, nitrate positive, positive growth in NaCl Pulmonary, skin, soft tissue and bone infections M. phlei 3-5 days growth; optimum temperature 30oC Coarsely wrinkled with deep yellow to orange pigment Key reactions: negative arylsulfatase, iron positive, NaCl negative Rare cause of pulmonary and soft tissue infections M. thermoresistable Rare Grows at 52oC M. abscessus Subspecies of M. chelonae Chronic lung disease, otitis media following tympanostomy, disseminated cutaneous infections
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Rapid Growers : M. chelonae - Arylsulfatase (+); 5% NaCl, iron uptake and Nitrate (-) M. fortuitum - Arylsulfatase (+) ; 5% NaCl, iron uptake and nitrate (+) Photochromogen Nitrate negative Strong Nitrate Positive M. kansaii Cat (+) M. marinum Tween 80 negative M. scrofulaceum Urease (+) M. gordonae Urease (-) Pigment Scotochromogen Non-chromogen Niacin positive Niacin negative M. Tuberculosis Nitrate (+), TCH (+) cat (-) NAP (-) TCH (+)/ PZA (+) TCH (-)/ PZA (-) M. Avium complex Tellurite and cat (+) M. bovis Tween 80 posistive
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Sterile wide mouth cup with tightly fitted lid Respiratory : First morning deep cough sputum, bronchial wash or brushing, BAL or bronchial lavage Cutanaeous lesions Body Fluids Pleural, ascitic pericardial, gastric, CSF, urine, joint aspirate, feces, etc.
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Culture media Egg based media (Lowenstein Jensen)- classical TB medium. Contains malachite green which suppresses the growth of gram positive bacteria Agar based media (Middlebrook 7H10) – contains casein hydrolysate (helps isolate isoniazid resistant stains), biotin and catalase (helps revive damaged bacilli); and albumin (binds toxins)
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1. Digestion: N-acetyl-L-cysteine (NALC) disrupts disulfide bonds of mucus, releasing organism 2.Decontamination 4% sodium hydroxide (NaOH) equally mixed with NALC destroys bacterial species (i.e. normal flora) other than mycobacterium Concentration Neutralization: Phosphate buffer of low specific gravity is added to mixture, and centrifuged at a high rate to concentrate the organism Albumin dilutes the mixture and heal the damaged cells
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Gram stains poorly due to high lipid content (mycolic acid) in cell wall Fluorescence or Carbolfuschin technique (i.e. Ziel Neelson or Kinyoun stain)
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Mantoux screening (tuberculin skin test) Read 48 hours later Positive skin test due to : 1) exposure to the antigen 2) Recovery from past infection(delayed type (IV) hypersensitivity) Reading the test: Healthy individuals – Induration (raised hardened area) of 15mm or greater is positive result Immunocompromised individuals–Induration greater than or equal to 5 mm is a positive result Quantiferon-TB gold Use whole blood Latent or active TB will stimulate interferon-gamma release from leukocytes Measured with ELISA
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Spread through direct contact or by inhalation via aerosols Slow growth (very difficult to culture in routine lab) Acid fast positive Two forms: Tuberculoid form – non-contagious hypo-pigmented skin macules with underlying nerve involvement causing loss of feeling Lepromatous form - highly contagious. Cell mediated immunity absent causing an increase development of the organism
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B.C.G NOT used as a vaccine for TB due to: Interference with skin test U.S. is a low risk population Varies in its ability to trigger immunity Dapsone + Rifampin + Clofazimine multidrug therapy which effectively treats both TB and leprosy (must be used in combination to prevent development of resistant organisms)
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