666 Modern Food Microbiology
Distribution
Y. enterocolitica and the related species noted in Table 28–3 are widely distributed in the terrestrial
environment and in lake, well, and stream waters, which are sources of the organisms to warm-blooded
animals. It is more animal adapted and is found more often among human isolates than the other
species in Table 28–3. Of 149 strains of human origin, 81%, 12%, 5.4%, and 2% were, respectively, Y.
enterocolitica, Yersinia intermedia, Yersinia frederiksenii, and Yersinia kristensenii.
114 Y. intermedia
and Y. frederiksenii are found mainly in fresh waters, fish, and foods, and only occasionally are isolated
from humans. Y. kristensenii is found mainly in soils and other environmental samples as well as in
foods but rarely isolated from humans.
7 Like Y. enterocolitica, this species produces a heat-stable
enterotoxin. Many of the Y. enterocolitica-like isolates of Hanna et al.
52 were rhamnose positive and,
consequently, are classified as Y. intermedia and/or Y. frederiksenii, and all grow at 4
◦ C. Rhamnosepositive yersiniae are not known to cause infections in humans.
Animals from which Y. enterocolitica has been isolated include cats, birds, dogs, beavers, guinea
pigs, rats, camels, horses, chickens, raccoons, chinchillas, deer, cattle, swine, lambs, fish, and oysters.
It is widely believed that swine constitutes the single most common source of Y. enterocolitica to
humans. Of 43 samples of pork obtained from a slaughterhouse and examined for Y. enterocolitica,
Y. intermedia, Y. kristensenii, and Y. frederiksenii, 8 were positive and all four species were found.
53
Along with Klebsiella pneumoniae, Y. enterocolitica was recovered from crabs collected near Kodiak
Island, Alaska, and was shown to be pathogenic.
4 In a study in the United States, 95 of 103 (92.2%)
lots of market hogs carried at least one Y. enterocolitica isolate, and 98.7% of the pathogenic isolates
were serotype 0:5 and 3.7% were 0:3.
46 In a study in Finland, 92% of 51 tongue and 25% of 255
ground meat samples contained Y. enterocolitica.
44 These investigators used a yadA gene-targeted
polymerase chain reaction (PCR) along with a culture method and by the two methods >98% of the
pork tongues were positive. Biotype 4 was the most common, as was serotype 0:3 (see below). A
TaqMan assay was compared to two other methods for their respective recovery of Y. enterocolitica
from fresh and frozen ground pork, and the sensitivity of TaqMan was 3 to 4 log 10 cfu/g or ml.
138
Results could be obtained in 5 hours after an 18-hour enrichment. The thin agar layer Oxyrase (TALO)
method could detect as few as 2 log 10 cfu/g of freeze-injured cells. Using these two methods along
with a standard selective medium, no Y. enterocolitica could be found in 100 ground pork samples.
138
In regard to human carriage, an examination was made of 4,841 stool specimens from seven cities
in as many U.S. states from November 1989 to January 1990, and the findings were as follows:
38%, 49%, 60%, and 98% contained, respectively, Y. enterocolitica, shigellae, Campylobacter, and
salmonellae.
75 Of the Y. enterocolitica isolates, 92% were serotype 0:3.
Serovars and Biovars
The most commonly occurring Y. enterocolitica serovars (serotypes) in human infections are 0:3,
0:5,27, 0:8, and 0:9. Each of 49 isolates belonging to these serovars produced a positive HeLa cell
response, whereas only 5 of 39 other serovars were positive.
88 Most pathogenic strains in the United
States are 0:8 (biovars 2 and 3), and except for occasional isolations in Canada, it is rarely reported from
other continents. In Canada, Africa, Europe, and Japan, serovar 0:3 (biovar 4) is the most common.
130
The second most common in Europe and Africa is 0:9, which has been reported also from Japan.
Serovar 0:3 (biovar 4, phage type 9b) was practically the only type found in the province of Quebec,
Canada, and it was predominant in Ontario.
130 The next most common were 0:5,27 and 0:6,30. From
human infections in Canada, 0:3 represented 85% of 256 isolates, whereas for nonhuman sources,
Distribution
Y. enterocolitica and the related species noted in Table 28–3 are widely distributed in the terrestrial
environment and in lake, well, and stream waters, which are sources of the organisms to warm-blooded
animals. It is more animal adapted and is found more often among human isolates than the other
species in Table 28–3. Of 149 strains of human origin, 81%, 12%, 5.4%, and 2% were, respectively, Y.
enterocolitica, Yersinia intermedia, Yersinia frederiksenii, and Yersinia kristensenii.
114 Y. intermedia
and Y. frederiksenii are found mainly in fresh waters, fish, and foods, and only occasionally are isolated
from humans. Y. kristensenii is found mainly in soils and other environmental samples as well as in
foods but rarely isolated from humans.
7 Like Y. enterocolitica, this species produces a heat-stable
enterotoxin. Many of the Y. enterocolitica-like isolates of Hanna et al.
52 were rhamnose positive and,
consequently, are classified as Y. intermedia and/or Y. frederiksenii, and all grow at 4
◦ C. Rhamnosepositive yersiniae are not known to cause infections in humans.
Animals from which Y. enterocolitica has been isolated include cats, birds, dogs, beavers, guinea
pigs, rats, camels, horses, chickens, raccoons, chinchillas, deer, cattle, swine, lambs, fish, and oysters.
It is widely believed that swine constitutes the single most common source of Y. enterocolitica to
humans. Of 43 samples of pork obtained from a slaughterhouse and examined for Y. enterocolitica,
Y. intermedia, Y. kristensenii, and Y. frederiksenii, 8 were positive and all four species were found.
53
Along with Klebsiella pneumoniae, Y. enterocolitica was recovered from crabs collected near Kodiak
Island, Alaska, and was shown to be pathogenic.
4 In a study in the United States, 95 of 103 (92.2%)
lots of market hogs carried at least one Y. enterocolitica isolate, and 98.7% of the pathogenic isolates
were serotype 0:5 and 3.7% were 0:3.
46 In a study in Finland, 92% of 51 tongue and 25% of 255
ground meat samples contained Y. enterocolitica.
44 These investigators used a yadA gene-targeted
polymerase chain reaction (PCR) along with a culture method and by the two methods >98% of the
pork tongues were positive. Biotype 4 was the most common, as was serotype 0:3 (see below). A
TaqMan assay was compared to two other methods for their respective recovery of Y. enterocolitica
from fresh and frozen ground pork, and the sensitivity of TaqMan was 3 to 4 log 10 cfu/g or ml.
138
Results could be obtained in 5 hours after an 18-hour enrichment. The thin agar layer Oxyrase (TALO)
method could detect as few as 2 log 10 cfu/g of freeze-injured cells. Using these two methods along
with a standard selective medium, no Y. enterocolitica could be found in 100 ground pork samples.
138
In regard to human carriage, an examination was made of 4,841 stool specimens from seven cities
in as many U.S. states from November 1989 to January 1990, and the findings were as follows:
38%, 49%, 60%, and 98% contained, respectively, Y. enterocolitica, shigellae, Campylobacter, and
salmonellae.
75 Of the Y. enterocolitica isolates, 92% were serotype 0:3.
Serovars and Biovars
The most commonly occurring Y. enterocolitica serovars (serotypes) in human infections are 0:3,
0:5,27, 0:8, and 0:9. Each of 49 isolates belonging to these serovars produced a positive HeLa cell
response, whereas only 5 of 39 other serovars were positive.
88 Most pathogenic strains in the United
States are 0:8 (biovars 2 and 3), and except for occasional isolations in Canada, it is rarely reported from
other continents. In Canada, Africa, Europe, and Japan, serovar 0:3 (biovar 4) is the most common.
130
The second most common in Europe and Africa is 0:9, which has been reported also from Japan.
Serovar 0:3 (biovar 4, phage type 9b) was practically the only type found in the province of Quebec,
Canada, and it was predominant in Ontario.
130 The next most common were 0:5,27 and 0:6,30. From
human infections in Canada, 0:3 represented 85% of 256 isolates, whereas for nonhuman sources,