In Vitro Determination of the Antimicrobial Properties of Two Cyanoacrylate Preparations GARY N. BLUM, WILLIAM A. NOLTE, and PAUL B. ROBERTSON Departments of Periodontics and Microbiology, University of Texas, Dental Branch, Houston, Texas 77067, USA Isobutyl and trifluoro cyanoacrylates showed varying degrees of inhibition for Lactobacil- lus casei and Staphylococcus aureus when tested by the spread plate technique. Can- dida albicans and Pseudomonas aeruginosa were resistant. The results tend to support the view that inhibition of growth was due to the vapor effect and not the diffusibility of the cyanoacrylates. Cyanoacrylate monomers have been found to be useful as tissue adhesives and hemo- static agents in medicine and dentistry and have a potential use as dressings in perio- dontal surgical procedures.1-4 Several inves- tigators have reported that isobutyl cyano- acrylate inhibited the growth of representa- tive gram-negative and gram-positive organ- isms.5-7 Jandinski and Sonis8 have reported growth inhibition of Streptococcus, Neisseria catarrhalis, Gaflyka, and Staphylococcus au- reus when the isobutyl cyanoacrylate polymer was applied to freshly inoculated Petri dishes. This investigation was undertaken to de- termine the antimicrobial properties of iso- butyl 2-cyanoacrylatea and trifluoro-l-methyl ethyl 2-cyanoacrylate.b Materials and Methods Isobutyl cyanoacrylate and trifluoro cyano- acrylate were evaluated for antimicrobial ac- tivity against Candida albicans AT10231, Lactobacillus casei ATI 1578, Pseudomonas aeruginosa, and Staphylococcus aureus. To This paper is based on a thesis submitted in partial fulfillment of the requirements for MS degree. This work was supported by USPHS Grant 5S01-RR- 05344-12. Received for publication June 3, 1974. Accepted for publication December 23, 1974. a Bucrylate, Johnson & Johnson, New Brunswick, NJ. b Flucrylate, 3M Co., St. Paul, Minn. 500 standardize the culture with regard to con- sistency of resistance of organisms and num- ber of cells, a series of two consecutive broth subcultures was made for each organism from a 48-hour-old stock slant culture. With a standard McFarland9 No. 4 nephelometer, dilutions were made i'n sterile saline solution to achieve final approximate organism counts of 1.2 X 104 and 6.0 X 104 cells per milliliter. The two cyanoacrylate compounds were cul- tured on Trypticase soy agare with 1% dex- trose, Trypticase soy broth,c and blood agar to test for sterility. No observable organism growth was evident in any of the tests with either of the materials at periods up to 72 hours. Several plating techniques were used to evaluate the cyanoacrylates for antimicrobial activity. For overlay techniques, saline sus- pensions of the test organisms were inocu- lated into warm melted Trypticase soy agar with dextrose and mixed. The resultant in- oculated agar was overlaid on previously poured 24-hour-old sterile Trypticase soy dextrose agar plates. One drop of each cy- anoacrylate compound or sterile saline solu- tion, used as control, was placed in the cen- ter of respective plates of the different test organisms. Spread plates were inoculated with 0.1 ml of each saline suspension of the test organism and this inoculum was spread over the agar surface. One drop of either cyanoacrylate compound or sterile saline solution was placed in the center of the respective plates of the test organisms. Broth culture techniques used 0.1% agar to localize the bacterial cells of the inoculum within the medium. One-tenth milliliter of each dilution of each organism was trans- c Baltimore Biological Laboratories, Cockeysville, Md.