Ans: A (Mycobacterium Gordonae) M. Marinum & M. Kansasii are photochromogenes while M. intracellulare & M. avium are non-photochromogenes.Scotochromogens# M, Gordonae (formely M.aquae) - Often found in tap water (hence called 'the tap water scotochromogen), is a common contaminant in clinical specimens and a rare cause of pulmonary disease.# M. Scrofulaceum - It is principally associated with scrofula or cervical lymphadenopathy, but also cause pulmonary disease.# M, szulgai - An uncommon cause of pulmonary disease & bursitis. It is a scotochromogen when incubated at 37degC but a photochromogen at 25degC.Table (Greenwood): Principal types of opportunist mycobacterial disease in man and the usual causative agentsDiseaseUsual causative agentLymphadenopathyM. avium complexM. scrofuiaceumSkin lesions Post-trauma abscessesM. chelonaeM. fortuitumM.terraeSwimming pool granulomaM. marinumBuruli ulcerM. ulceransPulmonary diseaseM avium complexM. kansasiiM. xenopiM. malmoenseDisseminated disease AIDS-relatedM. avium complexM. genevenseNon-AIDS-relatedM. avium complexM. chelanae A typical = Nontuberculous = Paratubercle Mycobacterium = MOTTClassified into four group by Runyon | | | | |1. PhntnchroiiiogenesProduce no pigment in dark & yellow orange pigment when exposed to light.i M.SimiaeQii M. AsiaticumQiii M. kansasiiQiv M. MarinumQ 2. Scotochromogenes: Form yellow-orange red colonies even in the darki. M. ScrofulaceumQii M.Szulagaiiii. M. GordonaeQ 3. NonphotochromogenesDo not form pigment even on exposure to lighti M. AviumQii M. XenopiQiii M. UlceransQiv M. JntracellulareQv M.Matmoensevi M. Shinshuensevii M. Paratuberculosisviii M. Sylvaticumix M. Lepraemuriumx M. terraexi M. Nonchromogenicumxii M. trivialexiii M. Haemophiiumxiv M. Genevense 4. Rapid growers: Thevare capable of rapid growth, colonies appearing within seven days of incubation at 37deg C or 25deg C.i M. ChelonaeQii M. ForuitumQiii M. SmegmatisQiv M. fiavescensQv M. VaccaeQ