Four of six California children in a confirmed E. coli outbreak cluster drank unpasteurized raw milk from Organic Pastures Dairy Co. before becoming ill in January, state officials said Monday. The California Department of Public Health (CDPH) reported lab tests show all six children had the same unique strain of Shiga-toxin producing E. coli O157. Some of the children required hospitalization. Health officials said it is investigating the possibility of additional victims. “CDPH is continuing to work with local health departments to identify potential case patients that might be associated with this cluster of illnesses,” a health department spokesman said. The department’s Food and Drug Branch (FDB) collected a number of samples from the marketplace. Test results were not yet available on Monday according to the state health department spokesman. The dairy owners are aware of the illnesses and are cooperating with the investigation, CDPH officials said. “FDB has also initiated an environmental investigation at the dairy, but since that investigation is ongoing, we cannot provide any specifics at this time.” Mark McAfee, founder and CEO of the Fresno-based dairy, said Monday the state had collected hundreds of samples from the dairy and none were positive. The dairy recalled two lots of its whole, raw milk via its Facebook page at 9 p.m. Feb. 4. One lot had an expiration date of Jan. 23. The other expired Jan. 26. Organic Pastures also posted the recall on its website. “Our food safety program saved the day,” McAfee said Monday when asked about the CDPH report. “It worked extremely well. We’re proud of that.” McAfee said the test-and-hold procedure at the 500-cow dairy isn’t a 100 percent guarantee that pathogens are not present in Organic Pastures raw milk products. Raw milk is not pasteurized, which kills harmful germs and bacteria including E. coli, Salmonella, Campylobacter and Listeria. The Organic Pastures testing procedure apparently failed on Jan. 6 when a batch of raw, unpasteurized milk returned a false negative, McAfee said. The milk was distributed. That false negative wasn’t apparent until last week, he said. On Jan. 7, a test on a batch of raw milk returned a positive result. McAfee said that raised a red flag. That milk was not distributed under the Organic Pastures brand. McAfee said he sold it to a company that pasteurizes milk. “We’ll never know for sure that the negative was actually false,” McAfee said of the Jan. 6 test. He said the current situation is the first of its kind and that the dairy is working with state officials and researchers at the University of California-Davis to learn from it. “The scientists always tell us that E. coli comes from manure. But we had a cow with E. coli on the inside of her udder. That’s never happened before,” McAfee said. The animal tested negative on Jan. 7 and positive for E. coli on Jan. 8. The dairy immediately quarantined the cow, McAfee said. “All of our manure tests are negative. … We spend thousands a month on food safety.” The dairy is now double testing its raw products before distribution, McAfee said. The company’s website references triple testing. “If anyone has ever been made sick by our milk we want to talk to them,” McAfee said. The past decade at Organic Pastures Previous recalls and foodborne illness outbreaks linked to Organic Pastures in the past decade include: October 2015 – Organic Pastures raw milk recall and quarantine after CDFA inspectors found Campylobacter as a result of product testing conducted as part of routine inspection and sample collection at the facility. September 2012 – Organic Pastures raw milk recall and quarantine after CDFA inspectors found Campylobacter bacteria as a result of product testing conducted as part of routine inspection and sample collection at the facility. January-April 2012 – Organic Pastures products linked to campylobacter outbreak. Raw milk, raw skim milk, raw cream and raw butter were recalled and the dairy quarantined after the confirmed detection of campylobacter bacteria in raw cream. State officials identified at least 10 people with campylobacter infections throughout California. They reported consuming Organic Pastures raw milk prior to illness onset. Their median age was 11.5 years, with six younger than 18. The age range was nine months to 38 years. August-October 2011 — Organic Pastures products linked to E. coli outbreak. A cluster of five young children with E. coli O157:H7 infections with matching pulse-field gel electrophoresis (PFGE) patterns was identified. Illness onsets were from Aug. 25 to Oct. 25. All five children reported drinking commercially available raw milk from a single dairy, Organic Pastures, and had no other common exposures. Investigations by the CDPH’s Food and Drug Branch and the California Department of Food and Agriculture showed environmental samples collected at Organic Pastures yielded E. coli O157:H7 isolates that had PFGE patterns indistinguishable from the patient isolates. September 2008 — Organic Pastures Grade A raw cream recall and quarantine after state testing and confirmation testing detected campylobacter bacteria in the cream. September 2007 — Organic Pastures Grade A raw cream recall and quarantine following laboratory confirmation of the presence of Listeria monocytogenes bacteria. CDFA inspectors found the bacteria as a result of product testing conducted as part of routine inspection and sample collection at the facility. November-December 2007 — Organic Pastures cows linked to Campylobacter outbreak. State officials found 50 strains of Campylobacter jejuni plus Campylobacter coli, Campylobacter fetus, Campylobacter hyointetinalis and Campylobacter lari when they cultured feces from Organic Pastures dairy cow feces. There was only one patient isolate available for DNA fingerprinting, but it was identical to isolates from four cattle fecal samples collected at Organic Pastures. September 2006 — Organic Pastures linked to E. coli O157:H7 outbreak. Six sick children were identified by state officials. Four had culture-confirmed infections, one had a culture-confirmed infection and HUS (hemolytic uremic syndrome, which can result in kidney failure and stroke), and one had HUS only. The median age of patients was 8 years, with a range of 6 to 18 years. Organic Pastures’ operators claimed the illnesses were linked to consumption of fresh spinach that was linked to a separate E. coli outbreak in 2006. However, the five children who consumed Organic Pastures’ products who had culture confirmation were laboratory matches to each other and the CDC reported their specific E. coli isolates “differed markedly from the patterns of the concurrent E. coli O157:H7 outbreak strain associated with spinach consumption.” (To sign up for a free subscription to Food Safety News, click here.)