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Corynebacterium macginleyi: susceptibility to 7 usual ophthalmic antibiotics

Abstract number: P1397

Somodevilla Á., Domingo D., Martinez M.C., Alarcón T., Lopéz-Brea M.

Objectives: Clinical importance of Corynebacterium macginleyi isolated from conjunctival infections has been recently recognized.

The aim of this study was to evaluate the susceptibility of 23 Corynebacterium macginleyi isolates obtained from conjunctival samples (November 2006 to June 2008) to 7 usual ophthalmic antibiotics: penicillin, gentamicin, ciprofloxacin, tetracycline, vancomicin, rifampicin and linezolid.

Methods: Conjunctival swabs obtained from symptomatic patients were cultured onto blood and chocolate agar and incubated in aerobic and microaerophilic environment, respectively. Plates were incubated for two days.

Identification was performed using the API Coryne system (bioMérieux).

Susceptibility was determined by microdilution broth method according to CLSI breakpoints and using its recomendations as well: Cation-adjusted Mueller-Hinton broth with lysed horse blood (2.5 to 5% v/v), 35°C, aerobic atmosphere and 24 to 48 hours of incubation.

Results: After 48 hours of incubation all the strains were susceptible to penicillin (leqslant R: less-than-or-eq, slant1 mg/l), gentamicin (leqslant R: less-than-or-eq, slant4 mg/l), vancomicin (leqslant R: less-than-or-eq, slant4 mg/l), rifampicin (leqslant R: less-than-or-eq, slant1 mg/l) and linezolid (leqslant R: less-than-or-eq, slant2 mg/l). Only one strain was resistant to ciprofloxacin (16 mg/l geqslant R: gt-or-equal, slanted 4 mg/l) and another to tetracycline (64 mg/l geqslant R: gt-or-equal, slanted 16 mg/l).

MIC50 and MIC90 obtained were as follows: leqslant R: less-than-or-eq, slant0.06 mg/l and leqslant R: less-than-or-eq, slant0.06 mg/l, leqslant R: less-than-or-eq, slant 0.06 mg/l and 0.25 mg/l, leqslant R: less-than-or-eq, slant 0.06 mg/l and 0.25 mg/l, 0.5 mg/l and 1 mg/l, 0.5 mg/l and 1 mg/l, leqslant R: less-than-or-eq, slant0.06 mg/l andleqslant R: less-than-or-eq, slant 0.06 mg/l, 0.25 mg/l and 1 mg/l to penicillin, gentamicin, ciprofloxacin, tetracycline, vancomicin, rifampicin and linezolid, respectively.

Conclusions:Corynebacterium macginleyi showed high susceptibility to all the ophthalmic antibiotics tested.

Only two strains were found to be resistant to one of them: ciprofloxacin or tetracyclin.

From these data we conclude that antimicrobial treatment of C. macginleyi obtained from ophthalmic samples is not an important problem, at least for the time being.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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