Fundamental Food Microbiology, Third Edition - Fuad Fathir

374 FUNDAMENTAL FOOD MICROBIOLOGY
has been implicated in many outbreaks in the U.S., Europe, and Canada. The affected
people were found to have consumed improperly cooked, contaminated hamburgers.
In a 1993 outbreak, affecting over 500 people and causing 4 deaths, consumption
of hamburgers served by a fast-food chain in Washington, Nevada, Oregon, and
California was implicated. The hamburgers, contaminated with Esc. coli O157:H7,
were cooked at a temperature that failed to kill the pathogen. In addition to ground
beef, other foods, such as raw milk, apple cider, some fruits, uncooked sausages,
sprouts, and salad have been implicated. Investigations revealed the presence of Esc.
coli O157:H7 in many different types of foods of animal origin, such as ground
beef, pork, poultry, lamb, and raw milk, in low percentages. The organism was
isolated in low frequencies from dairy cows as well as calves and chickens. 17–21
5. Prevention
Proper sanitation, cooking or heating at appropriate temperatures, proper refrigeration,
and prevention of cross-contamination should be practiced in order to control
the presence of Esc. coli O157:H7 in a ready-to-eat food. The Food Safety Inspection
Service (FSIS) in the U.S. has provided the following guidelines to control foodborne
illness from this pathogen: use only pasteurized milk; quickly refrigerate or freeze
perishable foods; never thaw a food at room temperature or keep a refrigerated food
at room temperature over 2 h; wash hands, utensils, and work areas with hot soapy
water after contact with raw meat and meat patties; cook meat or patties until the
center is gray or brown; and prevent fecal–oral contamination through proper personal
hygiene. 17–21
V. SHIGELLOSIS (BACILLARY DYSENTERY) BY SHIGELLA SPP.
A. Importance
The genus Shigella contains four species: Shigella dysenteriae, Shi, flexneri, Shi.
boydii and Shi. sonnei and each species has several serovars. Only humans and some
primates are their hosts. The organisms are either transmitted directly through
fecal–oral routes or indirectly through fecal-contaminated food and water. While in
most developed countries transmission through drinking water has been reduced, in
developing countries contaminated drinking water is a major cause of shigellosis.
The disease is prevalent in some geographic locations, particularly in Asia, Mexico,
and South America. It occurs more frequently in places with poor sanitation. In the
U.S., shigellosis occurs more among migrant workers, on Indian reservations, in
poor urban institutions, and in day-care centers. Children below 5 years of age are
more affected. In developing countries, there is a high fatality rate among children
suffering from shigellosis. In the U.S., before the 1950s, the predominant species
was Shi. dysenteriae. At present, the predominant species is Shi. sonnei. In the U.S.
between 1983 and 1987, there were 44 outbreaks affecting 9971 people, with 2
deaths. In one outbreak in 1987, several thousand people were affected by eating
commercial meals prepared under poor hygienic conditions that resulted in