Most common form of Nocardial respiratory tract infection is -

Ans. is 'd' i.e., Pneumonia * Nocardia are 'gram positive' 'acid fast' filaments.* Nocardia are strict aerobes and partially urease and catalase positive. Since nocardiae are among the few aerobic microorganism that use paraffin as a carbon source, paraffin baiting can be used to isolate the organism from mixed culture.* Nocardia are acid-fast and are most commonly stained by Ziehl-Neelson (ZN) stain. Other acid fast stains used are Kinyon stain and Fitefaraco stain.* Nocardia can also be stained by mucin stains like mucicarmine stain and alcian blue stain.Clinical manifestations* Most common species causing human disease is N asteroids. N brasiliensis is other species causing disease.* Clinical manifestations may be:i) Respiratory: Pneumonia is most common manifestation of nocardia infection.ii) Extrapulmonary: Most common site of involvement is brain and brain abscess is most characteristic lesion. Other infections are keratitis, cellulitis, and actinomycetoma.Treatment* Sulfonamide is the drug of choice. Cotrimoxazole is equally effective. Minocycline is best alternative.*Amikacin is the drug of choice for perentral use.