L-627. Corynebacterium amycolatum in Otic Infections
Session: Poster Session: Aggressive Unusual Infections from Around the World
Saturday, October 25, 2008: 12:00 AM
Room: Hall C
Background: Recently, Corynebacterium amycolatum has been reported as an emerging pathogen particularly in nosocomial infections of immunosuppressed patients. Isolates of C. amycolatum have been described as resistant to multiple antibiotics, although the specific clinical source of the isolates has not always been identified. In recent otic clinical studies of acute otitis externa or acute otitis media with tympanostomy tubes, numerous isolates of C. amycolatum have been recovered and characterized.
Methods: DNA-based methods, automated ribotyping and comparative sequence analysis of the 16S rRNA gene, were used to identify coryneform bacteria recovered from clinical specimens. Susceptibility profiles of the C. amycolatum isolates were determined by microtiter broth dilution MIC testing in MHB supplemented with 2.5% lysed horse blood. Results: In previous clinical studies conducted from 1998 - 2001, 28 C. amycolatum isolates were recovered from 3070 patients while in recent studies (2006-2008), 128 C. amycolatum isolates were recovered from 1709 patients. The susceptibility profile for all 156 isolates demonstrated 50% or more of the isolates were resistant to macrolides, clindamycin, fluoroquinolones, and trimethoprim. High level resistance was occasionally seen to aminoglycosides, β-lactams, tetracyclines, fusidic acid, chloramphenicol, and vancomycin.
Conclusions: The frequency with which C. amycolatum is recovered in otic infections has increased in the last ten years from 1 in 100 patients to 1 in 13 patients. The reason for this notable increase in frequency of occurrence is not known. As has been observed by others, this species exhibits a remarkable capability to become resistant to a wide variety of antibiotics.
Celeste McLean1, David Stroman, PhD2, Linda Clark, BS2 and  D. W. Stroman,
Alcon Laboratories Role(s): Employee, Received: Salary., (1)Alcon Research, Ltd., (2)Alcon Laboratories, Inc.