<prompt> Which of the following is active against atypical mycobacteria?ClarithromycinRifabutinCiprofloxacinAll of the above  <response>: Clarithromycin: The antimicrobial spectrum of clarithromycin is similar to erythromycin; in addition, it includes Mycobact. avium complex MAC, other atypical mycobacteria, M.leprae and some anaerobes but not Bact.fragilis. It is more active against sensitive strains of gram-positive cocci, Moraxella, Legionella, Mycoplasma pneumoniae and Helicobacter pylori. However, bacteria that have developed resistance to erythromycin are resistant to clarithromycin also. Rifabutin: It is related to rifampin in structure anC. mechanism of action; but less active against M. tuberculi and more active against MAC.For the treatment of established MAC infection, it has been added to ethambutol clarithromycin azithromycin Ciprofloxacin prototype: It is the most potent first generation FQ actie against a broad range of bacteria, the most susceptible ones are the aerobic gram-negatie bacilli, especially the Enterobacteriaceae and Neisseria. The MIC of ciprofloxacin against these bacteria is usually 0.1 J.Igml, while grampositive bacteria are inhibited at relatively higher concentrations. The spectrum of action is summarized below: Highly susceptible: E. coli K. pneumoniae Enterobacter Salmonella typhi other Salmonella Shigella Proteus Neisseria gonorrhoeae N. meningitidis H. influenzae H. ducreyi Campylobacter jejuni Yersinia enterocolitica Vibrio cholerae Moderately susceptible: Pseudomonas aeruginosa Staph. aureus including few MRSA Staph. epidermidis Branhamella catarrhalis Legionella Brucella Listeria Bacillus anthracis Mycobact. tuberculosis ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:688,689,730,744 