Which organism is identified as acid-fast bacilli?

The organism identified as acid-fast bacilli is Mycobacterium tuberculosis. Acid-fastness is a property of certain bacteria that retain dye even after being washed with acid-alcohol solutions. This characteristic is due to the presence of mycolic acids in the bacterial cell wall, making it resistant to decolorization.

Mycobacterium tuberculosis is a slow-growing, aerobic bacterium that causes tuberculosis in humans. It is crucial to identify it accurately, especially in clinical microbiology, as timely diagnosis and treatment are essential for controlling the spread of the disease.

Other options do not exhibit acid-fast properties. Escherichia coli, Staphylococcus aureus, and Streptococcus pneumoniae are not classified as acid-fast bacilli; they do not have the same cell wall structure and therefore cannot retain the dye during the acid wash process. Understanding the unique characteristics of bacteria, such as acid-fastness, helps in accurate identification and treatment of infections caused by these organisms.