Scanning electron microscopy of bacterial biofilms on indwelling bladder catheters

Abstract

Fifty Foley bladder catheters that had been indwelling for periods ranging from 3 to 83 days (mean 35 days) were examined for the presence of bacterial biofilm. Scanning electron microscopy on freeze-dried cross-sections and fixed, critical point-dried longitudinal sections revealed biofilm formation on the luminal surfaces of 44 of the catheters. Culture of urine samples and sonicates from catheters revealed that the prevalence of bacteriuria was less than that of catheter colonization. A wide range of nosocomial species were found colonizing the catheters, Escherichia coli being most often isolated. The bacterial composition of the biofilms ranged from single species to mixed communities containing up to four species. There was no relationship between the length of time that the catheter had been in situ and the extent of biofilm formation. The biofilms varied in thickness from 3 to 490 microns and were visible as layers of bacterial cells up to about 400 cells deep, embedded in a matrix.

Study on biofilm-forming properties of clinical isolates of Staphylococcus aureus

“…The sample was then coated with gold film by SEM JEOL JFC-1500 Quick auto sputter coater up to 300 Armstrong. The sample was then placed in a sample chamber of SEM JEOL JSM-6380A and scanning was performed under different magnifications ranging from 6,000x to 12,500x, and voltage 5kV [13,14].…”

“…A variety of methods have been standardized in various laboratories, each having their own merits. These methods include tissue culture plate (TCP) [7], tube method (TM) [8], Congo red agar method (CRA) [9], bioluminescent assay [10], light or fluorescent microscopic examination [11,12], air-liquid interface coverslip assay [7,8], and scanning electron microscopy (SEM) [13,14]. SEM is an advanced resolution method that provides ultrastructure analysis of biofilms.…”

“…The scanning electron microscope has an extensive magnification to about 210 times the limit of a light microscope. It displays whether biofilm is loosely expressed by bacteria in the surrounding medium or is definitely fixed to the bacteria allowing the bacteria to be embedded in a matrix [13,14].…”

Biofilm and Urogenital Infections

“…Bacteria can ascend the catheter also by an intraluminal route, which occurs when organisms gain access to the internal lumen of the catheter. These organisms are usually introduced from exogenous sources, for instance with cross transmission from the hands of health care personnel [13,32,33,35]. Adhesion of microorganisms to catheter materials depends on the hydrophobicity of the organism and catheter surface.…”

Nasal cytology: the “infectious spot”, an expression of a morphological-chromatic biofilm

“…The investigation of biofilms has increased its possibilities with the evolution of the methods of investigation, whereas the early work was based on scanning electron microscopy (SEM) [17], and transmission electron microscopy (TEM) [18], which clarify the ultramicroscopic fine structure. Indeed electron microscopy and specific staining of polysaccharides with ruthenium identify the nature of the extracellular fibers as biofilms and their association with cells [19,20].…”