year, a significant number of those affected
die from the disease. He has identified this
microorganism as a “super bacterium” that
can survive environmental extremes that will
eliminate other pathogenic bacteria. Thus,
food processors and foodservice operators
should focus on reducing the presence of this
microorganism in products, even though it is
nearly impossible to completely eliminate
this pathogen from the food supply.
Salmonellosis
Salmonellosis is considered a food infec-
tion because it results from the ingestion of
any one of numerous strains of living Salmo-
nellaorganisms. These microbes grow in a 5
to 47ºC (37ºC optimal temperature) environ-
ment and produce an endotoxin (a toxin
retained within the bacterial cell) that causes
the illness. The usual symptoms of salmonel-
losis are nausea, vomiting, and diarrhea,
which appear to result from the irritation of
the intestinal wall by the endotoxins. About
1 million of these microorganisms must be
ingested for an infection to occur. The time
lapse between ingestion and appearance of
symptoms of salmonellosis is generally
longer than that of staphylococcal food poi-
soning symptoms. Mortality from salmonel-
losis is generally low. Most deaths that occur
are among infants, the aged, or those already
debilitated from other illnesses. Celum et al.
(1987) reported that salmonellosis may be
especially harmful to persons with AIDS
and Archer (1988) stated that AIDS patients
are quite susceptible to this foodborne ill-
ness.
Salmonellae are facultative anaerobic,
gram-negative non-spore-forming, ova-
shaped bacteria that primarily originate
from the intestinal tract. This pathogen gen-
erally grows at an optimum Awof 0.86 in a
pH range of 3.6 to 9.5 with an optimum
range of 6.5 to 7.5. A salt concentration of
over 2% will retard growth, but this microbe
is very tolerant of freezing and drying. These
bacteria may be present in the intestinal tract
and other tissues of poultry and red meat
animals without producing any apparent
symptoms of infection in the animal. This
microorganism has been an enduring prob-
lem for fresh poultry and has been found on
up to 70% broiler carcasses. The epidemic of
Salmonella enteritidisin the northeastern
United States during 1988 was partially
attributable to poultry and shell eggs. A five-
fold increase of this serotype has occurred
since the late 1970s. This contaminant
appears to have entered the egg through
hairline cracks and fecal soiling of the shell
and ovarian infection in the hen. During the
past, eight food handlers in a grocery store
in McLean, Virginia, were found to be posi-
tive for S. enteritidis, which was attributed to
their using cracked eggs for food preparation
in gourmet foods.
Although Salmonellaorganisms can be
present in skeletal tissues, the major source of
the infection results from the contamination
of food by the handlers during processing,
through recontamination or cross-contami-
nation.Salmonellaetransferred by the finger-
tips are capable of surviving for several hours
and still contaminating food. Thermal pro-
cessing conditions for the destruction of
S. aureuswill destroy most species ofSalmo-
nella. Because of the origin of these bacteria
and their sensitivity to cold temperature, sal-
monellosis can usually be blamed on poor
sanitation and temperature abuse.Shigellosis
Shigellagastroenteritis (called shigellosis
or bacillary dysentery) is an infection with an
onset time of 1 to 7 days that endures 5 to 6
days. Primary symptoms vary with severe
cases that may result in bloody diarrhea,
mucus secretion, dehydration, fever, and
chills. Death may occur among immunocom-
promised individuals, but the mortality rateThe Relationship of Microorganisms to Sanitation 47