MEASUREMENT OF BACTERIAL-GROWTH RATES ON POLYMERS

A video microscope system and a mathematical model were developed to o bserve and model the early stage of bacterial growth on polymer surfac es. Glass slides were coated with polyorthoester, poly(L-lactic acid), and polysulfone, and inserted into a laminar flow cell to expose them to bacterial cultures of Staphylococcus epidermidis, Pseudomonas aeru ginosa, or Escherichia coli. The free energy of adhesion (Delta F-adh) was determined from contact-angle measurements. The microscopic obser vations along with the mathematical model allowed measurement of the r ates of adhesion, release, and growth. The growth rate of P. aeruginos a on the various surd aces correlated to the Delta F-adh. The growth r ates of all species on all of the surfaces were slower than the growth rates of the bacteria in suspension. The mathematical model is valid for early growth before the bacteria form a complete monolayer, and is useful in predicting and modeling early growth of bacteria on implant ed biomaterials. (C) 1996 John Wiley & Sons, Inc.