A sputum culture from a patient in Texas has buff colored colonies growing in approximately 4 weeks. After exposure to light, the colonies turn intense yellow. This isolate is most likely

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The buff colored colonies growing in 4 weeks followed by intense yellow color upon light exposure is a classic feature of M. kansasii. This organism is commonly found in Texas and is known to cause pulmonary disease in immunocompromised patients or those with pre-existing lung disease. M. scrofulaceum and M. xenopi are also slow growing organisms that can cause pulmonary disease, but do not typically exhibit the yellow color change. M. fortuitum is a rapid-grower and would not take 4 weeks to show growth.

A Sputum Culture from a Patient in Texas Has Buff