or poisons range from slight to severe and
may result in death.Salmonella,Shigella,
and enterococci bacteria causing different
types of intestinal disorders are the most
common.
Personal Contamination of Food Products
The intrinsic factors that affect microbial
contamination by people are as follows.
- Body location. The composition of the
normal microbial flora varies depend-
ing on the body area. The face, neck,
hands, and hair contain a higher pro-
portion of transient microorganisms
and a higher bacterial density. The
exposed areas of the body are more
vulnerable to contamination from envi-
ronmental sources. When environmen-
tal conditions change, the microbial
flora adapt to the new environment. - Age. The microbial population changes
as a person matures. This trend is espe-
cially true for adolescents entering
puberty. They produce large quantities
of lipids known as sebum, which pro-
motes the formation of acne caused by
Propionibacterium acnes. - Hair. Because of the density and oil
production, the hair on the scalp
enhances the growth of microbes such
asS. aureusandPityrosporum. - pH. The pH of the skin is affected
through the secretion of lactic acid
from the sweat glands, bacterial pro-
duction of fatty acids, and diffusion of
carbon dioxide through the skin. The
approximate pH value for the skin (5.5)
is more selective against transient
microorganisms than it is against the
resident flora. Factors that change the
pH of the skin (soap, creams, etc.) alter
the normal microbial flora. - Nutrients. Perspiration contains water-
soluble nutrients (i.e., inorganic ions
and some acids), whereas sebum con-
tains lipid (oil)-soluble materials such
as triglycerides, esters, and cholesterol.
The role of perspiration and sebum in
the growth of microorganisms is not
fully understood.
Humans are the most common contami-
nation source of food. People transmit dis-
eases as carriers. A carrier is a person who
harbors and discharges pathogens but does
not exhibit the symptoms of the disease.
Carriers are divided into three groups:- Convalescent carriers. People who, after
recovering from an infectious disease,
continue to harbor the causative organ-
ism for a variable length of time, usu-
ally less than 10 weeks. - Chronic carriers. People who continue
to harbor the infectious organism
indefinitely, although they do not show
symptoms of the disease. - Contact carriers. People who acquire
and harbor a pathogen through close
contact with an infected person but do
not acquire the disease.
People harbor a number of organisms,
including:●Streptococci. These organisms, com-
monly harbored in the human throat
and intestines, are responsible for a
wider variety of diseases than other bac-
teria. They are also frequently responsi-
ble for the development of secondary
infections.
●Staphylococci. The most important sin-
gle reservoir of staphylococci infection
of humans is the nasal cavity. Equally
important to the food industries are
those who possess the pathogenic vari-
eties of the organism as part of their
natural skin flora. These people are a
constant threat to consumer safety if