Header graphic for print
Marler Blog Providing Commentary on Food Poisoning Outbreaks & Litigation

Freshway E. coli O145 Romaine Lettuce Outbreak – the CDC Steps in

According to the CDC as a few moments ago, local and state public health officials in Michigan, New York, and Ohio are investigating human illnesses caused by E. coli O145. CDC is supporting these investigations and facilitating regular communication and information sharing between the states and with the U.S. Food and Drug Administration (FDA).

As of May 5, 2010, a total of 19 confirmed and 10 probable cases related to this outbreak have been reported from 3 states since March 1, 2010. The number of ill persons identified in each state with this strain is strain is: MI (10 confirmed and 3 probable), NY (2 confirmed and 5 probable), and OH (7 confirmed and 2 probable).

Among the confirmed and probable cases with reported dates available, illnesses began between April 10, 2010 and April 26, 2010. Infected individuals range in age from 13 years old to 29 years old and the median age is 19 years. Sixty-nine percent of patients are male. Among the 29 patients with available information, 12 (41%) were hospitalized. Three patients have developed a type of kidney failure known as hemolytic-uremic syndrome, or HUS. No deaths have been reported.

The outbreak can be visually described with a chart showing the number of persons who became ill each day. This chart is called an epidemic curve or epi curve. Of note, it takes an average of 2 to 3 weeks from the time a person becomes ill to the time when the illness is confirmed by laboratory testing and reported. Please see the E. coli Outbreak Investigations: Timeline for Reporting Cases for more details.

The bacteria responsible for this outbreak are referred to as Shiga toxin-producing E. coli, or STEC. STECs have been associated with human illness, including bloody diarrhea and a potentially fatal kidney condition called hemolytic-uremic syndrome (HUS). STEC bacteria are grouped by serotypes (e.g., O157 or O145). The STEC serotype found most commonly in U.S. patients is E. coli O157. Other E. coli serotypes in the STEC group, including O145, are sometimes called “non-O157 STECs.” Currently, there are limited public health surveillance data on the occurrence of non-O157 STECs, including E. coli O145, therefore E.coli O145 may go unreported. Because it is more difficult to identify than E. coli O157, many clinical laboratories do not test for non-O157 STEC infection.

Investigators are using pulsed-field gel electrophoresis (PFGE), a type of DNA fingerprint analysis of E. coli bacteria obtained through diagnostic testing to identify cases of illness that might be part of this outbreak. This testing is done in public health laboratories as part of the PulseNet network. Investigators have established a common definition of confirmed and probable cases related to this outbreak. Investigators have established a common definition of confirmed and probable cases related to this outbreak:

Confirmed cases are persons with:

(1) E. coli O145 infection, or E. coli infection with O Group pending, AND
(2) an illness onset on or after March 1, 2010, AND
(3) a DNA fingerprint matching the outbreak strain; AND
(4) an epidemiologic link to the outbreak.

Probable cases are persons with an epidemiologic link to the outbreak and:

(1) E. coli O145 infection with an illness onset on or after March 1, 2010 regardless of DNA fingerprint pattern, AND/OR
(2) hemolytic-uremic syndrome; AND/OR
(3) a laboratory isolate positive for Shiga toxin 2 [stx2] or isolate positive for Shiga toxin, but toxin type is unknown or pending.