I read the article by Dohar et al 1 with interest. Their finding concerning the efficacy of piperacillin and tobramycin against aural isolates of Pseudomonas aeruginosa is consistent with the sensitivity data at our institution in Honolulu, Hawaii (piperacillin, 97%; tobramycin, 100%). In Hawaii, otitis externa caused by Pseudomonas is common because of tropical weather and frequency of year-round water sports. From 1993 to 1995, we found that several additional antibiotics were at least as effective as piperacillin for aural isolates of Pseudomonas : ceftazidime (100%), imipenem (100%), and aztreonam (98%). These antibiotics are approved for children and are especially useful in patients who are allergic to penicillin. These antibiotics can be given by intramuscular or intravenous injection, and, because of their longer half-lives, can be given at 8- to 12-hour intervals. Therefore, ceftazidime, imipenem, and aztreonam are more amenable than piperacillin for outpatient antibiotic therapy of serious Pseudomonas ear infections,