hepatitis has been found in the intestinal
tract over 5 years after the disease symptoms
have disappeared. To explain the importance
of employee hygienic practices, it is benefi-
cial to look at different parts of the human
body in terms of potential sources of bacter-
ial contamination.
Skin
This living organ provides four major func-
tions: protection, sensation, heat regulation,
and elimination. Protection is an important
function in terms of personal hygiene. The
epidermis (outer layer of skin) and the der-
mis (inner layer of skin) are tough, pliable,
elastic layers that provide resistance to dam-
age from the environment. The epidermis is
less subject to damage than other parts of the
body because it does not contain nervous tis-
sue or blood vessels. The outermost layer of
the epidermis is called the corneum. Cells of
the corneum consist of 25 to 30 rows. They
tend to be flatter and softer than most other
cells and function through the formation of a
layer that is impermeable to microorganisms.
This layer is important to the distribution of
transient and resident microbial flora. These
tissues are replaced with newly created cells
from the underlying layers every 4 to 5 days
as they wear away. These dead cells are 30 ×
0.6μm in diameter and are easily dislodged
in clothing or disseminated into the air. The
dermis, an underlying layer of skin, is com-
posed of connective tissue, elastic fibers,
blood and lymph vessels, nervous tissue, mus-
cle tissue, glands, and ducts. The glands of
the dermis secrete perspiration and oil. The
skin functions as a working organ through
constant deposition of perspiration, oil, and
dead cells on the outer surface. When these
materials mix with environmental substances
such as dust, dirt, and grease, they form an
ideal environment for bacterial growth. Thus,
the skin becomes a potential source of bacte-
rial contamination. As the secretions build
up and the bacteria continue to grow, the skin
may become irritated. Food handlers may
rub and scratch the area, thereby transferring
bacteria to food. Improper hand washing and
infrequent bathing increases the amount of
microorganisms dispersed with the dead cell
fragments. Contamination results in shorten-
ing the product’s shelf life or in foodborne ill-
ness.
Foodborne illness may occur if a food
handler is a carrier ofStaphylococcus aureus
orStaphylococcus epidermis, two of the pre-
dominant bacterial species normally present
on the skin. These organisms are present in
the hair follicles and in the ducts of sweat
glands. They are capable of causing
abscesses, boils, and wound infections fol-
lowing surgical operations. As secretions
occur, perspiration from the eccrine gland, as
well as sebum (a fatty material seated into
hair follicles) contains bacteria from the
gland and subsequently deposits them on the
skin surface, with subsequent reinfection.
Certain genera of bacteria do not grow on
the skin because the skin acts as a physical
barrier and also secretes chemicals that can
destroy some of the microorganisms that are
foreign to it. This self-disinfectant character-
istic is most effective when the skin is clean.
The epidermis contains cracks, crevices,
and hollows that can provide a favorable envi-
ronment for microorganisms. Bacteria also
grow in hair follicles and in the sweat seba-
ceous glands. Because hands are very tactile,
the opportunity for cuts, calluses, and contact
with a wide variety of microorganisms is evi-
dent. Hands are in association with so much
of the environment that contact with contam-
inating bacteria is unavoidable.
Resident bacteria of the skin, which are
not easily removed, live in microcolonies that
are usually buried deep in the pores of the
skin and protected by fatty secretions of the