Microscopic examination remains the initial diagnostic test infor the processing of
specimens in the clinical microbiology laboratory. The timely report of a Gram stain
result gives the physician important information about the presence and cause of
infection. The Gram stain has a broad staining spectrum and classifies bacteria as either
Gram-positive or Gram-negative. Despite the clinical importance of the Gram stain,
there are few available standards for the reading and interpretation of this test. The
assignment of semi-quantitative and quantitative values to the number of cells and
bacteria seen is clearly arbitrary, since published criteria for general use vary
varies dramatically (1-5).