![]() ![]() For sterile body fluids, the sensitivity of Gram stain may be increased by cytospin centrifugation prior to staining (particularly cerebrospinal fluid). Īny bacteria detected on Gram stain of a sterile site specimen should be considered significant, although a negative Gram stain does not exclude infection. Colonizing bacteria rarely contaminate specimens from sterile sites in sufficient quantities to be detected on Gram stain. Fluid and/or tissue from these sites should be collected under sterile conditions (examples include cerebrospinal fluid, pleural fluid, pericardial fluid, synovial fluid, and peritoneal fluid). Sterile sites - Sterile sites refer to anatomic sites in which bacterial organisms are not present in the absence of infection. ![]() Basic fuchsin (present in dilute carbol fuchsin) stains many gram-negative bacteria more intensely than the other two stains. Counterstain with safranin, basic fuchsin, or neutral red.The decolorization step is critical, and it must be timed correctly if the decolorizing agent is left on too long, crystal violet stain will be removed from gram-positive cells as well as gram-negative cells. Perform rapid decolorization (a matter of seconds) with acetone or alcohol.Immerse the slide in mordant (Gram's iodine).Apply the primary stain (crystal violet) to the slide rinse with water.Prepare a heat-fixed smear of processed clinical specimen or a bacterial culture on a glass slide.Procedure - Performing a Gram stain consists of the following steps : Gram staining also allows visualization of yeast. Gram staining of clinical specimens (including sterile and nonsterile body fluid specimens, biopsy specimens, and positive culture specimens) is useful for guiding empiric clinical management for bacterial infections pending definitive culture data and/or molecular data. The method is named after Danish scientist Hans Christian Gram (1853 to 1938), who developed the technique in order to distinguish between two different bacterial causes of pneumonia ( Streptococcus pneumoniae and Klebsiella pneumoniae). GRAM STAIN - The Gram stain is used to differentiate between different types of bacteria based on the biochemical properties of their cell walls. Issues relating to the management of specific infections are discussed in detail separately. Issues relating to the interpretation of Gram stain and culture results are discussed here. Good specimen collection should avoid contamination with surrounding colonizing bacteria, provide an adequate volume of material for Gram stain and culture, be collected prior to initiation of antimicrobial therapy and labelled carefully with relevant clinical information, and be transported to the laboratory in a timely manner. The choice of the specimen sent for Gram stain and culture depends on the site of the infection and the likely pathogens. The quality of the clinical specimen can impact the value of the Gram stain performed. Therefore, it is important that such studies are performed and interpreted correctly. INTRODUCTION - Clinical decisions regarding the management of infections are frequently based on the results of Gram stain and culture. ![]()
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