Chapter 7:	Microbiology
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Gram Stain Bacterial organisms are broadly classified into one of four groups by performing a gram stain. The classifications include: Gram-positive rods Gram-positive cocci Gram-negative rods Gram-negative cocci

The bacteria can be then be further classified as being either aerobic or anaerobic.

Cultures and Sensitivity Tests

Cultures involve the propagation of microorganisms or living tissue cells in special media conducive to their growth. These tests are performed whenever identification of specific organisms is needed to prescribe therapies. Most cultures can be completed within two or three days, but some, such as mycobacterium tuberculosis can take as long as eight weeks. Once the organism has been identified, it is necessary to conduct sensitivity tests to ascertain the most appropriate and effective antibiotic therapy.

Using a technique called the acid-fast stain generally tests for the presence of mycobacterium organisms. Urinalysis is used to diagnose diseases involving the liver, kidney, cardiovascular, and endocrine systems. Pleural fluid analysis is used to distinguish transudate and exudate fluids in the pleural space.