Aztreonam, which is active only against gram-negative bacilli, also is useful when given in a single dose.

• 第三代头孢菌素如头孢他啶单剂量使用是有效的，作为仅对革兰氏阴性杆菌有效的阿奇霉素，（单剂量使用）也同样有效。