<prompt> In Bact. fragilis infection drug of choice isAzithromycinGentamicinClindamycinAztreonam  <response>: C. i.e. Clindamycin 731 - KDT 6th CLINDAMYCIN. Potent lincosamide antibioticIt inhibits most gram positive cocci, C. diphtheriae, Nocardia Actinomyces, Toxoplasma High activity against a variety of anaerobes especially Bact.fragilis AZITHROMYCIN - more active than other macrolides against H. influenzae High activity is exerted on respiratory pathogens- Mycoplasma, Chla. pneumonia, Legionella, Moraxella and on others like Campylobacter, Ch. trachomatis, H. ducreyi, Calymm. granulomatis, N. gonorrhoeae.CLARITHROMYCIN - More active against sensitive strains of gram - positive cocci, Moraxella, Legionella. Mycopneumoniae and Helicobacter- pylori. 