Sensitivity and spectrum of bacterial isolates in infectious otitis externa.

OBJECTIVE

To determine the spectrum and antibiotic sensitivity pattern of organisms from aural swabs taken from cases of infectious otitis externa.

DESIGN

Descriptive study.

PLACE AND DURATION OF STUDY

Department of ENT, Combined Military Hospital, Peshawar, from May 2002 to April 2003.

SUBJECTS AND METHODS

One hundred and twenty-four patients, diagnosed clinically as infectious otitis externa without concomitant suppurative otitis media, perforated tympanic membrane or otomycosis, were selected for the study. Samples of pus from external auditory canal were taken on sterile cotton swabs and were cultured on blood agar and MacConkey Agar for 24 to 48 hours. Sensitivity was tested and interpreted by Kirby-Bauer disc diffusion method of grading zones of inhibition.

RESULTS

One hundred and twenty four subjects were cultured. Sixteen samples showed no growth. One hundred and eight specimens yielded growth of bacteria. No specimen revealed multiple organisms. Staphylococcus aureus was found in 38%, and Pseudomonas aeruginosa was found in other 38%. Others included Proteus, Enterococci, Klebsiella, and E. coli. Majority of organisms were resistant to co-trimoxazole, amoxicillin and erythromycin, while 100% were sensitive to imipenem. Sensitivity to enoxacin was 96%, Ninety-two percent were sensitive to ciprofloxacin and ofloxacin.

CONCLUSION

Pseudomonas aeruginosa and Staphylococcus aureus were the most common bacterial isolates. Both were sensitive to fluoroquinolones. The latter can be used empirically for treatment of acute infectious otitis externa.