6 WOUND INFECTION 
addition to those causing the trouble. It should be noted that in wound 
infections it is impossible to predict from the general character of 
the lesions the species of bacteria which are producing them although 
certain bacteria cause tissue changes that seem to be somewhat 
peculiar to their species. The infecting organisms can usually be 
found microscopically without trouble in properly stained cover- 
glass preparations made from the lesions and most of them can be 
readily cultivated on ordinary media. B. pyogenes, however, 
requires special media for its development and most characteristic 
growth. 
Morbid anatomy of wound infection. ‘The tissue changes resulting 
from an infection of the body with various microérganisms belong 
with those considered in general 
pathology under the headings of 
inflammation, degeneration, other 
retrograde disturbances and regen- 
erative processes. The pathology 
of ordinary wound infections con- 
sists of an acute inflammation 
usually leading to suppuration, 
necrosis or gangrene; sometimes 
the lesions are chronic in nature 
resulting in a productive inflam- 
mation, and again they exhibit 
Fie.2. micrococcusrrocmnes. praw- the various forms of exudates. In 
ING FROM A COVER-GLASS PREPAR- Other instances infection results in 
at witeor OU Cemorrhages of ‘yarying degrees. 
Occasionally the lesions may be- 
come localized, as in pneumonia, lymphangitis, intestinal ulcers, 
nephritis, hepatitis and the like. The morbid anatomy of wound 
infection includes the variety of changes found in different forms of 
inflammation. Because of this, the emphasis of the pathology of 
infection rests on the etiology and the distribution within the body 
of the morbid changes. It has been shown that certain infections 
are slow in bringing about tissue changes and consequently many 
lesions resulting from wound infection may, when they appear, 
be considered as distinct maladies. 
Prevention of infection. In surgical operations, wound infection 
may be prevented by properly disinfecting the field of operation, 
