Gram-negative

Erythromycin is active against gram-positive and certain gram-negative bacteria, also against Rickettsia and spirochaetes. It is used for patients who are allergic to or do not respond to treatment with penicillins or tetracyclines. 

Tetracyclines are broad-spectrum antibiotics. effective against Gram-positive and Gram-negative bacteria, also against Rickettsiae (typhus fever) and certain other organisms. 

Tetracyclines. The tetracycliaes are a small group of antibiotics characterized as containing a polyhydronaphthacene nucleus. Commercially the tetracyclines are very important. They have been used clinically against gram-positive and gram-negative bacteria, spirochete, mycoplasmas, and rickettsiae... 

General Antibacterial Properties. In the clinical control of bacterial infectious disease, the aminoglycosides gentamicin, tobramycin, amikacin, netilmicin, and to a lesser extent, dibekacin and isepamicin are most commonly used for the treatment of serious infections involving aerobic or facultative gram-negative baciUi, especially in the compromised host. This usage is discussed in the Hterature (44—51). 

In 1945 it was noted that a strain of Cephalosporium acremonium i oAu ced antibiotic material that was active against gram-negative as weU as gram-positive... 

Gram-negative organisms produce ced-bound P-lactamases which reside in the periplasmic space. Thus, for gram-negative bacteria, the antibiotic must penetrate the outer ced membrane/wad before coming in contact with a P-lactamase (80,139,140). 

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