Which of the following is not an established antimicrobial drug synergism at the clinical level?
Amphotericin B and flucytosine in cryptococcal meningitis
Carbenicillin and gentamicin in pseudomonal infections
Penicillin and tetracycline in bacterial meningitis
Trimethoprim and sulfamethoxazole in coliform infections
Combination of a bacteriostatic and a bactericidal drug in most cases is antagonistic. Bactericidal drugs act on fast multiplying organisms whereas bacteriostatic drugs inhibit the growth. Here, penicillin is bactericidal whereas tetracyclines are bacteriostatic.