Recovery Rate of Cells of the Seven Regulated Serogroups of Shiga Toxin-Producing Escherichia coli from Raw Veal Cutlets, Ground Veal, and Ground Beef from Retail Stores in the Mid-Atlantic Region of the United States

Authors: JUNG, YANGJIN - Former ARS Employee; Porto-Fett, Anna; PARVEEN, SALINA - University Of Maryland Eastern Shore (UMES); MEREDITH, JOAN - University Of Maryland Eastern Shore (UMES); Shoyer, Brad; HENRY, ELIZABETH - Former ARS Employee; TRAUGER, ZACHARY - Former ARS Employee; Shane, Laura; Osorio, Manuela; SCHWARZ, JURGEN - University Of Maryland Eastern Shore (UMES); RUPERT, CHRISTOPHER - North Carolina State University; CHAPMAN, BENJAMIN - North Carolina State University; MOXLEY, RODNEY - University Of Nebraska; Luchansky, John

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2020
Publication Date: 2/1/2021
Citation: Jung, Y., Porto Fett, A.C., Parveen, S., Meredith, J., Shoyer, B.A., Henry, E., Trauger, Z., Shane, L.E., Osoria, M., Schwarz, J., Rupert, C., Chapman, B., Moxley, R., Luchansky, J.B. 2021. Recovery rate of cells of the seven regulated serogroups of shiga toxin-producing Escherichia coli from raw veal cutlets, ground veal, and ground beef from retail stores in the mid-atlantic region of the United States. Journal of Food Protection. 84(2):220-232. https://doi.org/10.4315/JFP-20-290.
DOI: https://doi.org/10.4315/JFP-20-290

Interpretive Summary: Shiga toxin-producing Escherichia coli (STEC) pose a significant threat to public health as evidenced by their occasional recovery from raw meat, and by the number and magnitude of recalls and associated illnesses attributed to STEC and beef that continue to occur. Although considerable information has been published on the recovery rates of serotype O157:H7 strains in raw beef, not much information is available on the comparative prevalence of the six additional regulated STEC serogroups associated with raw veal and/or beef, particularly for retail products. Therefore, we collected raw ground veal and ground beef samples from food retailers across the Mid-Atlantic region of the U.S. to establish and compare the true recovery rates of the regulated six serogroups of non-O157 STEC and E. coli O157:H7 in raw veal versus raw beef, and to subsequently characterize their genetic relatedness. Among 482 veal cutlet, 555 ground veal, and 540 ground beef samples purchased from retail establishments in the Mid-Atlantic region of the U.S. between 2014 and 2017, the recovery rates of non-O157 STEC from veal cutlets (3.94%, 19 of 482 samples) and ground veal (7.03%, 39 of 555 samples) were significantly higher (P less than 0.05) than from ground beef (0.93%, 5 of 540 samples). A single isolate of E. coli O157:H7 was recovered from ground veal (0.18%; 1 of 555), whereas the pathogen was not recovered from veal cutlet or ground beef samples. Regarding their genetic similarity, DNA fingerprinting of the 270 STEC isolates recovered from the 64 samples testing positive were clustered by into 39 “groups” (at greater than or equal to 90% similarity); multiple isolates (up to 5 from a single sample) from 43 of 64 (67.7%) positive samples showed indistinguishable fingerprints. These findings support related data from regulatory sampling exercises over the past decade and confirm that the recovery rates for the regulated STEC serogroups are appreciably higher for raw veal compared to raw beef samples as observed herein for meat purchased at food retailers in the Mid-Atlantic region of the U.S.

Technical Abstract: A total of 482 veal cutlet, 555 ground veal, and 540 ground beef samples were purchased from retail establishments in the Mid-Atlantic region of the U.S. over a non-contiguous, two-year period between 2014 and 2017. Samples (325 g each) were individually enriched and screened via real-time PCR for all seven regulated serogroup of Shiga toxin-producing Escherichia coli (STEC). Presumptive STEC positive samples were subjected to serogroup-specific immunomagnetic separation and plated onto selective media. Next, up to five isolates typical for STEC from each sample were analyzed via multiplex PCR for both virulence genes (i.e., eae, stx1 and/or stx2, and ehxA) and serogroup-specific gene(s) for one of the seven regulated STEC serogroup. The recovery rates of non-O157 STEC from veal cutlets (3.94%, 19 of 482 samples) and ground veal (7.03%, 39 of 555 samples) were significantly higher (P less than 0.05) than from ground beef (0.93%, 5 of 540 samples). In contrast, only a single isolate of STEC O157:H7 was recovered; this isolate originated from one (0.18%) of 555 samples of ground veal. Recovery rates for STEC were not associated with state, season, packaging type, brand, store type, meat condition, or fat content (P greater than 0.05). Pulsed-field subtyping of the 270 viable/confirmed STEC isolates from the 64 total samples testing positive revealed 78 pulsotypes (50 to 80% similarity) belonging to 39 pulsogroups with greater than or equal to 90% similarity within pulsogroups. Also, multiple isolates from the same sample displayed an indistinguishable pulsotype for 43 of 64 (67.7%) samples testing positive. The data herein may be used to estimate the comparative recovery of the regulated STEC serovars among retail veal and beef samples. These data will also be useful to support risk assessments, inform policy decisions, and develop interventions to reduce the risk of STEC associated with veal and beef products in the event of undercooking and/or improper handling or storage.