IN-VITRO SUSCEPTIBILITY OF AURAL ISOLATES OF PSEUDOMONAS-AERUGINOSA TO COMMONLY USED OTOTOPICAL ANTIBIOTICS

The choice of antimicrobial agents used to treat Pseudomonas aeruginos a infections of the ear is quite empiric. Yet in spite of this, very l ittle has been published ex amining susceptibility patterns of aural i solates of P. aeruginosa. Recently, increasing concern has emerged ove r the development of resistance to many of the commonly used ototopica l preparations with activity against P. aeruginosa. This concern stems from the fact that these preparations have been in use for a long tim e, and P. aeruginosa is known to develop resistance fairly readily. We prospectively studied the susceptibilities of aural isolates of P. ae ruginosa in 231 consecutive children who were seen in the outpatient P ediatric Otolaryngology Department at Children's Hospital of Pittsburg h during the years 1992 and 1993. The agents tested included neomycin, polymyxin B, colistin, and norfloxacin. We found that only 17.8% of t he isolates were sensitive to neomycin, as opposed to >95% for each of the other agents tested (polymyxin B, 99.6%; colistin, 97.4%; and nor floxacin, 98.3%). This difference proved to be statistically significa nt (p < 0.05). Given the concern of aminoglycoside-induced ototoxicity and the high rate of neomycin resistance, we believe that further inv estigation of other alternative ototopic agents with activity against P. aeruginosa is warranted.