Microbiologic Studies

Microbiologic studies that allow for direct examination of a specimen (e.g., sputum, blood, or urine) also may aid in a presumptive diagnosis and give an indication of the characteristics of the infecting organism. Generally, microbial cultures are obtained with a Gram stain of the cultured material.

A Gram stain of collected specimens can give rapid information that can be applied immediately to patient care. A Gram stain is performed to identify if bacteria are present and to determine morphologic characteristics of bacteria (such as gram-positive or gram-negative or shape—cocci, bacilli). Certain specimens do not stain well or at all and must be identified by alternative staining techniques (Mycoplasma spp., Legionella spp., Mycobacterium spp.). Figure 69-2 identifies bacterial pathogens as classified by Gram stain and morphologic characteristics. The presence of WBCs on a Gram stain indicates inflammation and suggests that the identified bacteria are pathogenic. The Gram stain may be useful in judging a sputum specimen's adequacy. For example, the presence of epithelial cells on sputum Gram stain suggests that the specimen is either poorly collected or contaminated. A poor specimen can give misleading information regarding the underlying pathogen and is a waste of laboratory personnel time and patient cost.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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