Rapid quantification of staphylococci adhered to titanium surfaces using image analyzed epifluorescence microscopy

A method for rapid enumeration of S. epidermidis adhered to the surface of commercially pure titanium samples was developed using image analyzed epifluorescence microscopy. The method was used to determine the effects of different surface roughnesses of titanium samples and the influence of adsorbed human serum proteins on bacterial adherence. Bacterial suspension of S. epidermidis (VAS-11, concentration: 10(7) cfu/ml) were incubated with titanium samples (with different surface roughnesses and coated with human serum albumin or fibronectin) for 1 h at 37 degrees C with agitation. Thereafter they were washed, stained with propidium iodide, air dried, mounted onto microslides, and counted by using image analyzed epifluorescence microscopy. The results showed that: (1) this direct counting method is quick, simple, accurate, reproducible, and suitable for counting bacteria adhered to opaque surfaces such as metal, (2) the different roughnesses of the titanium surfaces (roughness: 1.25 to 0.44 Ra) had no effect on the S. epidermidis adherence, and (3) adsorbed human serum albumin reduced the S. epidermidis adherence by more than 90%, suggesting that precoating biomaterials with albumin may reduce the possibility of prosthesis or implant colonization by staphylococci. Conversely, human serum fibronectin had no effect on S. epidermidis adherence to a titanium surface.