<prompt> Which of the following drugs combination shows antimicrobial synergism?Penicillin Streptomycin in SABEAmpicillin Tetracycline in endocarditisSulfamethoxazole Trimethoprim in UTIAmphotericin B Flucytosine in cryptococcal meningitis  <response>: Every AMA has a specific effect on selected microorganisms. Depending on the drug pair as well as the organism involved, either synergism supra-additive effect, additive action, indifference or antagonism may be observed when two AMAs belonging to different classes are used together Every combination is unique; the same drugs may be synergistic for one organism but antagonistic for another. However, general guidelines are: a Two bacteriostatic agents are often additive, rarely synergistic,i.e. combination of tetracyclines, chloramphenicol, erythromycin, etc. b Two bactericidal drugs are frequently additive and sometime synergistic if the organism is sensitive to both, e.g.: Penicillin ampicillin streptomycin gentamicin or vancomycin gentamicin for enterococcal SABE. Penicillins by acting on the cell wall may enhance the penetration of the aminoglycoside into the bacterium c Combination of a bactericidal with a bacteriostatic drug may be synergistic or antagonistic depending on the organism ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:677 