sulfa drug vs tetracycline

sulfa drug

noun
  • Any of a group of antibiotic drugs structurally related to sulphonamide, tending to be bacteriostatic rather than bacteriocidal. 

tetracycline

noun
  • Any of a large group of antibiotics with the same general structure derived from tetracene with many hydroxyl and other groups. 

  • A yellow crystalline broad-spectrum antibiotic C₂₂H₂₄N₂O₈ produced by streptomyces or synthetically. 

How often have the words sulfa drug and tetracycline occurred in a corpus of books? (source: Google Ngram Viewer )