Inhalable dry powder aztreonam for treatment and prevention of pulmonary bacterial infections

A method of treatment for pulmonary infections caused by gram-negative bacteria Burkholderia cepacia, Stenotrophomonas maltophilia, Alcaligenes xylosoxidans, and multidrug resistant Pseudomonas aeruginosa, said method comprising steps:

• a. preparing a concentrated inhalable aztreonam formulation consisting of from about 1 to about 200 mg of purified aztreonam base, or a pharmaceutically acceptable salt thereof in an inhalable dry powder form, said dry powder having particle size between 1 and 5 microns and pH from 4.0 to 7.5;
• and
• b. delivering said aztreonam dry powder or the aztreonam salt to the lung endobronchial space of airways of a patient in need thereof by a dry powder or meter dose inhaler;
• provided that the pharmaceutically acceptable salt is not arginine.