title: Aminopenicillins and superinfection by gram-negative rods.
mesh_terms: D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006801:Humans; D010403:Penicillin Resistance; D010406:Penicillins / Q000627:therapeutic use*; D012141:Respiratory Tract Infections / Q000188:drug therapy / Q000382:microbiology*
chemical_list: D010406:Penicillins