Escherichia coli O157 and other Shiga Toxin-Producing E. Coli Infection and Hemolytic Uremic Syndrome 
Annual Summary of Reportable Diseases

During 2022, 698 Shiga toxin producing Escherichia coli (STEC) cases were reported. Of those, 62 were culture-confirmed E. coli O157, 334 were culture-confirmed non-O157 STEC, and 302 were only positive by a culture-independent test (CIDT) and not subsequently culture-confirmed.

The 62 culture-confirmed cases of E. coli O157 infection (1.08 per 100,000 population) reported in 2022 represents a 46% decrease from the median number of culture-confirmed cases reported annually from 2012 to 2021 (median, 115 cases; range, 65 to 143). During 2022, 30 (48%) cases occurred in the metropolitan area. Forty-six (74%) cases occurred during May through October. The median age of the cases was 32 years (range, 11 months to 91 years). Eighteen percent of the cases were 4 years of age or younger. Nineteen (31%) cases were hospitalized; the median hospital stay was 6 days (range, 1 to 15 days). No cases died.

The 334 culture-confirmed non-O157 cases (5.84 per 100,000 population) reported in 2022 represents a 71% increase from the median number of culture-confirmed cases reported annually from 2012 to 2021 (median, 195 cases; range, 101 to 269). Six STEC serogroups accounted for 59% of non-O157 cases: E. coli O111 was the serogroup for 59 (18%) cases, E. coli O103 for 53 (16%), E. coli O26 for 33 (10%), E. coli O145 for 25 (7%), E. coli O121 for 16 (5%), and E. coli O45 for 12 (4%). The median age of the non-O157 STEC cases was 30 years (range, 5 months to 93 years). Sixty-five (19%) cases were hospitalized; the median hospital stay was 2 days (range, 1 to 32 days). Two cases died: an 84 year-old died of Clostridioides difficile, chronic renal disease, and diabetes the same day that E. coli O17/44/77:H18 was isolated from stool; and, an 84 year-old died of sepsis and intra-abdominal infection 2 days after E. coli 9:H30 was isolated from stool.

During 2022, 302 STEC cases with specimens that were positive by a CIDT conducted at a clinical laboratory and not subsequently culture-confirmed were reported. CIDTs have become widely adopted by clinical laboratories for the detection of Shiga toxin or Shiga toxin genes in stool. The median age of the CIDT-positive only cases was 36 years (range, 19 days to 92 years). Forty-five (15%) cases were hospitalized; the median hospital stay was 3 days (range, 1 to 19 days). Three cases died: a three year-old died of complications from rotavirus and respiratory infections the same day as a stool specimen tested positive for STEC by CIDT; a five year-old died of complications from a norovirus infection the same day as a stool specimen tested positive for STEC by CIDT; and, a 70 year-old died of metastatic rectal and colon cancer and norovirus infection 11 days after a stool specimen tested positive for STEC by CIDT.

Two E. coli O157 outbreaks were identified during 2022. One outbreak was due to foodborne transmission, and the other was due to person-to-person transmission in a childcare setting.

In August, a national outbreak of E. coli O157 infections was associated with spinach. Two laboratory confirmed cases were identified in Minnesota. Neither case developed hemolytic uremic syndrome (HUS) nor died.

In September, an outbreak of E. coli O157 infections associated with person-to-person transmission occurred at a childcare facility in Scott County; nine cases, including four laboratory-confirmed, were identified. No cases developed HUS nor died.

Seven non-O157 STEC outbreaks were identified during 2022. Three outbreaks were due to foodborne transmission, three were due to person-to-person transmission in childcare settings, and one was due to animal contact.

In July, an outbreak of E. coli O111:H8 infections was associated with a restaurant. A cabbage and carrot mix was statistically associated with illness, but bean sprouts, basil, and mint could not conclusively be ruled out as potential vehicles. The source of contamination was not identified. Fourteen patron cases were identified, including four that were laboratory-confirmed. Three laboratory-confirmed food workers were also identified. No cases developed HUS nor died.

In August, an outbreak of E. coli O26:H11 infections was associated with a restaurant. Sirloin steak and parsley were identified as potential vehicles. Eight cases, five laboratoryconfirmed, were identified. No cases developed HUS nor died.

In August, an outbreak of E. coli O111:H8 infections was associated with animal contact at a county fair. Six cases, four laboratory-confirmed, were identified. Environmental testing revealed evidence of STEC contamination in a barnyard and show arena barn. Two cases developed HUS, but none died.

In August, an outbreak of E. coli O45:H2 infections associated with person-to-person transmission occurred at a childcare facility in Carver County. Twenty-one cases, five laboratory-confirmed, were identified. No cases developed HUS nor died.

In August, an outbreak of E. coli O111:H8 infections associated with person-to-person transmission occurred at a childcare facility in Waseca County. Eleven cases, seven laboratory-confirmed, were identified. One case developed HUS, but none died.

In October, an outbreak of E. coli O71:H11 infections was associated with a restaurant. House-made chip dip and hamburgers were identified as potential vehicles. Three cases, two laboratory-confirmed, were identified. No cases developed HUS nor died.

In October, an outbreak of E. coli O111:H8 infections associated with person-to-person transmission occurred at a childcare facility in Dakota County. Two cases, both laboratory-confirmed, were identified. Neither case developed HUS nor died.

Hemolytic Uremic Syndrome (HUS)

In 2022, 15 HUS cases were reported. The number of reported cases was 36% higher than the median number of cases reported annually from 2012 to 2021 (median, 11 cases; range, 4 to 17). In 2022, the median age of HUS cases was 20 years (range, 8 months to 81 years). All 15 cases were hospitalized, with a median hospital stay of 12 days (range, 4 to 18 days). No cases died. E. coli O157:H7 was cultured from the stool of 5 (33%) cases. E. coli O111:H8 was cultured from the stool of two cases, E. coli O145:H28 was cultured from the stool of two cases, E. coli O168:H8 was cultured from the stool of one case, and E. coli O17/44/77:H18 was cultured from the stool of one case. Four cases were Shiga toxin positive by PCR but not culture-confirmed. In 2022, there were three outbreak-associated HUS cases. From 1997 through 2022, the overall case fatality rate among HUS cases was 4.9%.

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During 2021, 584 Shiga toxin producing Escherichia coli (STEC) cases were reported. Of those, 69 were culture-confirmed E. coli O157, 263 were culture-confirmed non-O157 STEC, and 252 were only positive by a culture-independent test (CIDT) and not subsequently culture-confirmed.

The 69 culture-confirmed cases of E. coli O157 infection (1.22 per 100,000 population) reported in 2021 represents a 42% decrease from the median number of culture-confirmed cases reported annually from 2011 to 2020 (median, 119 cases; range, 65 to 146). During 2021, 32 (46%) cases occurred in the metropolitan area. Fifty-five (80%) cases occurred during May through October. The median age of the cases was 17 years (range, 11 months to 79 years). Twenty-nine percent of the cases were 4 years of age or younger. Twenty-four (35%) cases were hospitalized; the median hospital stay was 3 days (range, 1 to 31 days). No cases died.

The 263 culture-confirmed non-O157 cases (4.65 per 100,000 population) reported in 2021 represents a 53% increase from the median number of culture-confirmed cases reported annually from 2011 to 2020 (median, 172 cases; range, 105 to 322). E. coli O103 was the serogroup for 42 (17%) cases, E. coli O26 for 34 (17%), E. coli O111 for 33 (13%), E. coli O145 for 19 (4%), E. coli O121 for 15 (5%), and E. coli O45 for 6 (2%). The median age of the non-O157 STEC cases was 31 years (range, 4 months to 96 years). Fifty (19%) cases were hospitalized; the median hospital stay was 3 days (range, 1 to 32 days). No cases died.

During 2021, 252 cases were reported with specimens that were positive by a CIDT conducted at a clinical laboratory, but were not subsequently culture confirmed. CIDTs have become widely adopted by clinical laboratories for the detection of Shiga toxin or Shiga toxin genes in stool. The median age of the CIDT-positive only cases was 41 years (range, 4 months to 97 years). Seventy (27%) cases were hospitalized; the median hospital stay was 3 days (range, 1 to 56 days). Two cases died.

Two E. coli O157 outbreaks were identified during 2021. One outbreak was due to animal contact, and the other was due to foodborne transmission. In August, an outbreak of E. coli O157 infections was likely associated with indirect contact with a calf and sheep at a private home; three cases, all laboratory-confirmed, were identified. Two cases developed hemolytic uremic syndrome (HUS), but none of the cases died. In November, a national outbreak of E. coli O157 infections was associated with spinach. Two cases were identified in Minnesota, both laboratory-confirmed. Neither developed HUS nor died.

Four non-O157 STEC outbreaks were identified during 2021. One outbreak was due to person-toperson transmission in a childcare setting, one was due to foodborne transmission, one was due to animal contact, and one had an unknown transmission route. In July, an outbreak of E. coli O103:H11 infections associated with person to-person transmission occurred at a childcare facility in Polk County. Nineteen cases, one laboratory confirmed, were identified. No cases developed HUS nor died. In August, an outbreak of E. coli O145:H28 infections with an unknown transmission route was identified. Three cases, all laboratory-confirmed, were identified. No cases developed HUS nor died.In October, an outbreak of E. coli O111:H8 infections was associated with contact with calves at an apple orchard. Two cases, both laboratory-confirmed, were identified. Neither case developed HUS nor died. In December, a national outbreak of E. coli O121:H19 infections was associated with romaine lettuce. Two cases were identified in Minnesota. Neither developed HUS nor died.

Hemolytic Uremic Syndrome (HUS)

In 2021, 11 HUS cases were reported. The number of reported cases is the same as the median number of cases reported annually from 2011 to 2020 (median, 11 cases; range, 3 to 17). In 2021, the median age of HUS cases was 2 years (range, 1 to 11 years). All 11 cases were hospitalized, with a median hospital stay of 13 days (range, 1 to 31 days). No cases died. From 1997 through 2021, the overall case fatality rate among HUS cases was 5.1%. E. coli O157:H7 was cultured from the stool of 7 (64%) cases. E. coli O5:H9 was cultured from the stool of one case and E. coli O-genotype untypeable:H8 was cultured from the stool of one case. Two cases were Shiga toxin positive by PCR but not culture-confirmed. In 2021, there were two outbreakassociated HUS cases.

• For up to date information see:E. coli O157:H7 and HUS

During 2020, 65 culture-confirmed cases of Escherichia coli O157 infection (1.2 per 100,000 population) were reported. The number of reported cases represents a 48% decrease from the median number of cases reported annually from 2010 to 2019 (median, 124 cases; range, 96 to 146) (Figure 2). During 2020, 22 (34%) cases occurred in the metropolitan area. Forty-six (71%) cases occurred during May through October. The median age of the cases was 24 years (range, 10 months to 81 years). Eighteen percent of the cases were 4 years of age or younger. Twenty-three (35%) cases were hospitalized; the median hospital stay was 2 days (range, 1 to 17 days). No cases died.

In addition to the 65 culture-confirmed E. coli O157 cases, 193 cases of Shiga toxin-producing E. coli (STEC) infection other than O157 were identified in 2020. Among the 193 cases with non-O157 STEC, E. coli O103 was the serogroup for 33 (17%) cases, E. coli O26 for 33 (17%), E. coli O111 for 26 (13%), E. coli O121 for 9 (5%), E. coli O145 for 7 (4%), and E. coli O45 for 3 (2%). The median age of the non-O157 STEC cases was 24 years (range, 11 months to 92 years). Thirty-one (16%) cases were hospitalized; the median hospital stay was 2 days (range, 1 to 24 days). No cases died.

Culture-independent tests have become increasingly adopted by clinical laboratories for the detection of Shiga toxin or Shiga toxin genes in stool. One hundred-fifty-six patient specimens that were positive by a culture-independent test conducted at a clinical laboratory were not subsequently culture-confirmed, and therefore did not meet the surveillance case definition for inclusion in MDH case count totals.

Two E. coli O157 outbreaks were identified during 2020. In October, a national outbreak of E. coli O157 infections was associated with leafy greens. Two cases were identified in Minnesota. No cases developed HUS or died.In addition, there was one multistate investigation with 2 Minnesota cases that CDC classified as an outbreak with an unknown source.

Four non-O157 STEC outbreaks were identified during 2020. One outbreak was due to person-to person transmission in a childcare setting, and one was due to foodborne transmission. In February, an outbreak of E. coli O26:H11 infections associated with person-to-person transmission occurred at a childcare facility in Hennepin County. Three cases, two laboratory-confirmed, were identified. No cases developed HUS or died. In July, an outbreak of E. coli O26:H11 infections was associated with a restaurant in Scott County. Two cases, both laboratory-confirmed, were identified. Neither case developed HUS nor died. In addition, there were two multistate investigations that included 6 Minnesota cases which CDC classified as outbreaks with an unknown source.

Hemolytic Uremic Syndrome (HUS)

In 2020, 3 HUS cases were reported. The number of reported cases represents a 74% decrease from the median number of cases reported annually from 2010 to 2019 (median, 11.5 cases; range, 9 to 17). In 2020, the median age of HUS cases was 7 years (range, 1 year to 10 years). All 3 cases were hospitalized, with a median hospital stay of 17 days (range, 7 to 17 days). No cases died. From 1997 through 2020, the overall case fatality rate among HUS cases was 5.3%. All 3 HUS cases reported in 2020 were post diarrheal. E. coli O157:H7 was cultured from the stool of 2 (67%) cases. The third case was Shiga toxin positive by PCR but not culture-confirmed. In 2019, there were no outbreak-associated HUS cases.

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In 2019, 111 culture-confirmed cases of Escherichia coli O157 infection (1.98 per 100,000 population) were reported. The number of reported cases represents a 12% decrease from the median number of cases reported annually from 2009 to 2018 (median, 126.5 cases; range, 96 to 146). During 2019, 59 (53%) cases occurred in the metropolitan area. Sixty-eight (61%) cases occurred during May through October. The median age of the cases was 28 years (range, 1 to 91 years). Eleven percent of the cases were 4 years of age or younger. Forty-five (41%) cases were hospitalized; the median hospital stay was 3 days (range, 1 to 25 days). No cases died.

In addition to the 111 culture-confirmed E. coli O157 cases, 322 cases of Shiga toxin-producing E. coli (STEC) infection were identified in 2019. Among the 322 cases with STEC other than O157, E. coli O103 was the serogroup for 52 (16%) cases, E. coli O26 for 52 (16%), E. coli O111 for 51 (16%), E. coli O145 for 12 (4%), E. coli O121 for 7 (2%), and E. coli O45 for 5 (2%). The median age of the non-O157 STEC cases was 23.5 years (range, 5 months to 95 years). Forty-one (13%) cases were hospitalized; the median hospital stay was 3 days (range, 1 to 56 days). No cases died.

Culture-independent tests (CIDTs) have become increasingly adopted by clinical laboratories for the detection of Shiga toxin in stool. Two hundred fifty-one patient specimens that were positive by a CIDT conducted at a clinical laboratory were not subsequently culture-confirmed, and therefore did not meet the surveillance case definition for inclusion in MDH case count totals.

Five E. coli O157 outbreaks were identified during 2019. Four outbreaks were due to foodborne transmission, and one was due to animal contact. All four foodborne outbreaks were part of national investigations. The five outbreaks resulted in 46 laboratory-confirmed Minnesota cases with a median of 7 cases (range, 5 to 18 cases per outbreak). One outbreak was associated with animal contact at the Minnesota State Fair. Eleven laboratory-confirmed cases were identified. No cases developed hemolytic uremic syndrome (HUS) or died. A national outbreak was likely associated with frozen pizza. Eighteen cases were identified in Minnesota. No cases developed HUS or died. In November, a national outbreak of infections was associated with romaine lettuce from Salinas, California. Seven laboratory-confirmed cases were identified in Minnesota. Two cases developed HUS and neither died. In November, a national outbreak was associated with pre-packaged salad kits. Five laboratory-confirmed cases were identified in Minnesota. No cases developed HUS or died. In December, a national outbreak was associated with iceberg lettuce. Five laboratory-confirmed cases were identified in Minnesota. No cases developed HUS or died.

Seven non-O157 STEC outbreaks were identified during 2019. Four outbreaks were due to person-to-person transmission in child care settings, two were due to foodborne transmission, and one was due to waterborne transmission. A national outbreak of E. coli O103 infections was associated with consuming ground beef. One laboratory-confirmed case was identified in Minnesota. The case did not develop HUS or die.

An outbreak of E. coli O26:H11 infections associated with person-to-person transmission occurred at a childcare facility in Hennepin County. Six cases, all laboratory-confirmed, were identified. No cases developed HUS or died. A second outbreak of E. coli O26:H11 infections associated with person-to-person transmission occurred at a childcare facility in Hennepin County. Four cases, all laboratory-confirmed, were identified. No cases developed HUS or died. Another outbreak of E. coli O26:H11 infections associated with person-to-person transmission occurred at a child care facility in Olmsted County. Two cases, both laboratory-confirmed, were identified. Neither case developed HUS or died. Another outbreak of E. coli O26:H11 infections associated with person-to-person transmission occurred at a childcare facility in Wright County. Thirty-six cases, including 20 laboratory-confirmed, were identified. No cases developed HUS or died.

In August, an outbreak of E. coli O145:H28 infections was associated with a waterborne transmission at a lake in Hennepin County. Sixty-nine cases, including 4 laboratory-confirmed, were identified. No cases developed HUS or died.

An outbreak of E. coli O69:H11 infections was associated with a restaurant in Anoka County. Three cases, all laboratory-confirmed, were identified. No cases developed HUS or died.

Hemolytic Uremic Syndrome (HUS)

In 2019, 11 HUS cases were reported. The number of reported cases is similar to the median number of cases reported annually from 2009 to 2018 (median, 12.5 cases; range, 9 to 17). In 2019, the median age of HUS cases was 7 years (range, 1 year to 78 years); 6 of the 11 cases occurred in children <7 years of age. All 11 cases were hospitalized, with a median hospital stay of 15 days (range, 3 to 25 days). No cases died. From 1997 through 2019, the overall case fatality rate among HUS cases was 5.0%. Ten of the 11 HUS cases reported in 2019 were post-diarrheal. E. coli O157:H7 was cultured from the stool of 7 cases, E. coli O111:H8 was cultured from the stool of 1 case, and E. coli O55:H7 was isolated from the stool of 1 case. In 2019, there were 2 outbreak-associated HUS cases, both associated with a national outbreak due to romaine lettuce from Salinas, California. Both outbreak-associated HUS cases were hospitalized; the median hospital stay was 9 days (range, 3 to 15 days). Neither case died.

• For up to date information see:E. coli O157:H7 and HUS

During 2018, 115 culture-confirmed cases of Escherichia coli O157 infection (2.06 per 100,000 population) were reported. The number of reported cases represents a 10% decrease from the median number of cases reported annually from 2008 to 2017 (median, 126.5 cases; range, 96 to 146). During 2018, 52 (45%) cases occurred in the metropolitan area. Eighty-five (74%) cases occurred during May through October. The median age of the cases was 27 years (range, 7 months to 88 years). Twelve percent of the cases were 4 years of age or younger. Thirty (26%) cases were hospitalized; the median hospital stay was 3 days (range, 1 to 47 days). Two cases, a 73-year-old female and a 46-year-old female, died.

In addition to the 115 culture-confirmed E. coli O157 cases, 270 cases of Shiga toxin-producing E. coli (STEC) infection were identified. Of those, culture-confirmation was not possible in 1, and therefore it is unknown if this was O157 or another serogroup. Among the remaining 269 cases, E. coli O103 was the serogroup for 68 (25%) cases, E. coli O111 for 45 (17%), E. coli O26 for 28 (10%), E. coli O145 for 15 (6%), E. coli O121 for 10 (4%), and E. coli O45 for 5 (2%). The median age of the non-O157 STEC cases was 28.5 years (range, 4 months to 90 years). Forty-one (15%) cases were hospitalized; the median hospital stay was 2 days (range, 1 to 28 days). One case, a 63-year-old female, died.

Culture-independent tests (CIDTs) have become increasingly adopted by clinical laboratories for the detection of Shiga toxin in stool. Two hundred twenty-two patient specimens that were positive by a CIDT conducted at a clinical laboratory were not subsequently culture-confirmed, and therefore did not meet the surveillance case definition for inclusion in MDH case count totals.

Two E. coli O157 outbreaks were identified during 2018. Both outbreaks were due to foodborne transmission, and were part of national investigations. These outbreaks resulted in 14 laboratory-confirmed Minnesota cases, with 2 and 12 cases, respectively. In May, a national outbreak was associated with romaine lettuce. Twelve cases were identified in Minnesota. Three cases developed hemolytic uremic syndrome (HUS), and 2 cases died. In October, a national outbreak was associated with chicken salad. Two laboratory-confirmed cases were identified in Minnesota. Neither case developed HUS or died.

Three non-O157 STEC outbreaks were identified during 2018. One outbreak was due to person-toperson transmission, one was due to waterborne transmission, and one was due to animal contact. An outbreak of E. coli O111 infections was associated with a petting zoo at a campground. Five laboratory-confirmed cases were identified. Two cases developed HUS but none died. An outbreak of both E. coli O121 and Cryptosporidium infections was associated with a campground. Seventy-nine cases were identified, including 2 laboratoryconfirmed cases of E. coli O121 infections and 5 laboratory-confirmed cases of Cryptosporidium infections. No cases developed HUS or died. An outbreak of E. coli O103 infections associated with person-to-person transmission occurred at a childcare facility in Martin County. Five cases, including 1 laboratory-confirmed, were identified. No cases developed HUS or died.

Hemolytic Uremic Syndrome (HUS)

In 2018, 11 HUS cases were reported. The number of reported cases is similar to the median number of cases reported annually from 2008 to 2017 (median, 12.5 cases; range, 9 to 17). In 2018, the median age of HUS cases was 46 years (range, 1 year to 81 years); 4 of the 11 cases occurred in children less than 7 years of age. All 11 cases were hospitalized, with a median hospital stay of 9 days (range, 3 to 48 days). From 1997 through 2018, the overall case fatality rate among HUS cases was 5.5%. Nine of the 11 HUS cases reported in 2018 were post-diarrheal. E. coli O157:H7 was cultured from the stool of 8 (73%) cases, E. coli O111 was cultured from the stool of 2 (18%) cases, and E. coli O777 was isolated from the stool of 1 (9%) case. In 2018, there were 5 outbreak-associated HUS cases. All outbreak-associated HUS cases were hospitalized; the median hospital stay was 11 days (range, 3 to 47 days), and 1 died.

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