423
Chapter 30
indicators of Bacterial
Pathogens
introduction
All pathogenic microorganisms implicated in foodborne diseases are considered enteric pathogens
except Staphylococcus aureus, Bacillus cereus, Clostridium botulinum (except in the case of infant botulism), Clo. perfringens, and toxicogenic molds. This means they can survive and multiply or establish in the gastrointestinal (GI) tract of humans, food animals, and birds. A food contaminated
directly or indirectly with fecal materials from these sources may theoretically contain one or more
of these pathogens and can thus be potentially hazardous to consumers. To implement regulatory
requirements and ensure consumer safety, it is necessary to know that a food is either free of some
enteric pathogens, such as Salmonella serovars and Escherichia coli O157:H7 or contains low levels
of some other enteric pathogens, such as Yersinia enterocolitica and Vibrio parahaemolyticus. The
procedures used to isolate and confirm a pathogen from a food involve several steps, take a relatively
long time, and are costly. Some of the new tests involving molecular biology techniques require
high initial investment and highly skilled technicians. In a modernized, large commercial operation, involving procurement of ingredients from many countries, processing of different products,
warehousing, distribution over a large area, and retail marketing, it is not practical or economical
to test the required number of product samples from each batch for all the pathogens or even those
that are suspected of being present in a particular product. Instead, food samples are examined
for the number (or level) of groups or a species of bacteria that are of fecal (enteric) origin, usually
present in a higher density than pathogens but usually considered to be nonpathogenic. Their presence is viewed as resulting from direct or indirect contamination of a food with fecal materials and
indicates the possible presence of enteric pathogens in the food. These bacterial groups or species are
termed indicators of enteric pathogens. Although Sta. aureus, Clo. botulinum, Clo. perfringens, and
Bac. cereus can be present in the fecal matter of humans and food animals, they, along with toxigenic molds, are not considered classical enteric pathogens. Their presence in a food is not normally
considered to be due to because of fecal contamination, and the indicators of enteric pathogens are
not very effective for the purpose. To determine the presence of these microorganisms and their
Chapter 30
indicators of Bacterial
Pathogens
introduction
All pathogenic microorganisms implicated in foodborne diseases are considered enteric pathogens
except Staphylococcus aureus, Bacillus cereus, Clostridium botulinum (except in the case of infant botulism), Clo. perfringens, and toxicogenic molds. This means they can survive and multiply or establish in the gastrointestinal (GI) tract of humans, food animals, and birds. A food contaminated
directly or indirectly with fecal materials from these sources may theoretically contain one or more
of these pathogens and can thus be potentially hazardous to consumers. To implement regulatory
requirements and ensure consumer safety, it is necessary to know that a food is either free of some
enteric pathogens, such as Salmonella serovars and Escherichia coli O157:H7 or contains low levels
of some other enteric pathogens, such as Yersinia enterocolitica and Vibrio parahaemolyticus. The
procedures used to isolate and confirm a pathogen from a food involve several steps, take a relatively
long time, and are costly. Some of the new tests involving molecular biology techniques require
high initial investment and highly skilled technicians. In a modernized, large commercial operation, involving procurement of ingredients from many countries, processing of different products,
warehousing, distribution over a large area, and retail marketing, it is not practical or economical
to test the required number of product samples from each batch for all the pathogens or even those
that are suspected of being present in a particular product. Instead, food samples are examined
for the number (or level) of groups or a species of bacteria that are of fecal (enteric) origin, usually
present in a higher density than pathogens but usually considered to be nonpathogenic. Their presence is viewed as resulting from direct or indirect contamination of a food with fecal materials and
indicates the possible presence of enteric pathogens in the food. These bacterial groups or species are
termed indicators of enteric pathogens. Although Sta. aureus, Clo. botulinum, Clo. perfringens, and
Bac. cereus can be present in the fecal matter of humans and food animals, they, along with toxigenic molds, are not considered classical enteric pathogens. Their presence in a food is not normally
considered to be due to because of fecal contamination, and the indicators of enteric pathogens are
not very effective for the purpose. To determine the presence of these microorganisms and their