Before diving in the deep end and talking about some microbiology, a basic introduction to some terms.
The most commonly used description of bacteria you will come across in a microbiology laboratory is
Gram negative or Gram positive. This refers to the result obtained when staining bacteria with a Gram stain, which is the first step used in classifying and identifying almost all bacteria.
Below is a diagram and a picture of a Gram stain of Gram negative bacilli. These organisms are rod shaped and stain red with the Gram stain.


Gram positive cocci are spherical and retain the blue colour of the Gram stain as in the diagram and picture below.


Generally Gram positive cocci prefer dry environments but Gram negative bacilli like moist environments and some can readily contaminate detergents and disinfectants.
Clinical infections associated with endoscopy may occur because infective agents are transmitted from one patient to the next via the endoscope or its accessory equipment.
Hospital environmental pathogens may also contaminate the endoscope or accessory equipment and be introduced into the patient during subsequent examination. Contamination may be from the general hospital environment, the water supply or disinfecting machines. Previously the risks of clinical infection from environmental pathogens related mainly to E.R.C.P. The more widespread use of endoscope reprocessing machines now makes this risk more relevant for many workplaces.
There are a number of organisms that are of importance in relation to endoscopy. This may be because of: