Webster's New World Medical Dictionary

yd.
Yard. 
yeast
A group of single-celled fungi that repro-
duce by budding. Most yeast is harmless, and yeast
is commonly present without ill effect on normal
human skin and mucous membranes, including the
gastrointestinal (GI) tract. In the GI tract, the
amount of yeast is usually controlled by helpful bac-
teria, although this balance can be upset by illness,
immune system problems, or antibiotic use.
Extreme overproliferation of yeast can cause dis-
comfort and disease. For example, the common
yeast Candida albicans (once called Monilia)
causes thrush and rashes, fingernail infections, vagi-
nal infections, and a host of other problems in
patients with immune deficiency. See also 
Candida
albicans; candidiasis; thrush; yeast infection;
yeast rash.
yeast diaper rash
Infection in the diaper area of
a baby that is caused by a yeast called Candida.
Certain conditions, such as antibiotic use or exces-
sive moisture, can upset the balance of microbes
and allow an overgrowth of Candida. The infected
skin is usually fiery red with areas that may have a
raised red border.
yeast infection
Overgrowth of yeast that affects
the skin (yeast rash), mouth (thrush), digestive
tract, esophagus, vagina (vaginitis), or other parts
of the body. Yeast infections occur most frequently
in moist areas of the body. Although Candida albi-
cans and other Candida yeasts are the most frequent
offenders, other yeast groups are known to cause
illness, primarily in immunocompromised patients.
Diagnosis is confirmed by culturing a stool or
mucosa sample or a scraping from the affected
area. Treatment involves use of topical or oral anti-
fungal medications. See also 
Candida albicans;
candidiasis; thrush; yeast vaginitis; yeast rash.