Gram positive vs gram negative slide skin#
Gram positive vs gram negative slide series#

Careful interpretation of the cells, and or bacteria shown in a Gram stain allow the health practitioners to differentiate between normal flora and true infection.Ī Gram stain is often routinely performed as part of the evaluation of a culture.

Gram positive vs gram negative slide skin#

With the exception of vaginal specimens, absence or presence of skin cells (epithelial cells) may represent a contaminated sample or a poor-quality specimen. Absence or presence of white blood cells in the Gram stain can help establish that an adequate sample was obtained as white blood cells are frequently present with an infection. Often, detecting the presence of microorganisms and determining whether an infection is caused by an organism that is Gram positive or Gram negative will be sufficient to allow a doctor to prescribe treatment with an appropriate empiric antibiotic while waiting for more specific tests, such as culture and antibiotic sensitivities, to be completed. Particularly in patients who are suspected of septicaemia, pneumonia and meningitis.Ī Gram stain and culture of the material from an infected site are the most commonly performed microbiology tests used to identify the cause of an infection. Since its discovery in 1884 by Danish scientist Hans Christian Gram, the Gram stain remains the most simple, fast and cost-effective test in microbiology, providing an incredible amount of information to health practitioners. Fungi (in the form of yeasts or moulds) may also be initially recognised with a Gram stain, but viruses cannot be seen with a Gram stain.

coli), a common cause of urinary tract infections. An example of a Gram negative bacterium is Escherichia coli (or E. Examples of Gram positive cocci include Staphylococcus aureus, the bacterium commonly known as 'Golden Staph'. The Gram stain colour and the bacterial shape give clues as to what microorganism might be causing the infection. Any bacteria that are present within the patient's white blood cell (intracellular) are also noted.

Shape - the most common shapes include round (cocci) or rod-shaped (bacilli)Īdditional information may be obtained by observing the groupings of the bacteria on the slide, such as cocci that are present singly, in pairs, in groups of four, in clusters or in chains, or bacilli that are thick, thin, short, long or have enlarged spores on one end.

Colour - typically bacteria may be either 'Gram positive' (purple) or 'Gram negative' (pink).

Any bacteria that may be present are categorised by colour and shape during the microscopic evaluation: It is based on the principle that most bacteria are visualised under the microscope more easily after staining, which gives them a colour, depending on the type of cell wall.

Gram positive vs gram negative slide series#

The slide is then treated with a series of special stains and examined under a microscope by trained laboratory staff. The Gram stain involves applying a sample from the infected area onto a glass slide and allowing it to dry. It gives relatively quick results as to the general type of bacteria that may be present. A Gram stain is a laboratory procedure used to detect the presence of microrganisms, especially bacteria, in a sample taken from the site of a suspected infection.