Research letter: Antibacterial activity of fluorescein CMAJ 1998;158:471 We conducted a simple experiment to determine if fluorescein has any antibacterial activity after one of us questioned its possible deleterious effect on bacteria if applied to an eye before collection of a swab for culture. A literature search failed to produce any information on this topic. Antibiotic susceptibility plates (Mueller­Hinton medium, BBL, Baltimore, Md.) were streaked (according to the Kirby­Bauer method1) with 1×108 organisms/mL of the following ATCC (American Type Culture Collection) strains: Moraxella catarrhalis, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae (Mueller­Hinton medium with 5% sheep blood) and Haemophilus influenzae (Haemophilus testing medium). A fluorescein sodium strip, instead of an antibiotic disk, was applied to each of the plates. We conclude that swabs for culture should be taken before fluorescein is applied to the eye, because of its antibacterial activity against organisms such as M. catarrhalis, S. pneumoniae and H. influenzae, pathogens that are frequently found in the eye. Jacques J. Roy, MD Alfred Lau, ART Microbiology Laboratory Royal Columbian Hospital New Westminster, BC Douglas G. McFee, MD Langley, BC Reference Bauer AW, et al. 1966. Antibiotic susceptibility testing by a standarized single-disk method. Am J Clin Pathol 1966;45:493-6. Send a letter to the editor responding to this article Envoyez une lettre à la rédaction au sujet de cet article | CMAJ February 24, 1998 (vol 158, no 4) / JAMC le 24 février 1998 (vol 158, no 4) |