Longitudinal Study of Listeria monocytogenes Prevalence and Persistence in Retail Delis Haley F. Oliver, PhD Purdue University 1 Interagency Risk Assessment - L. monocytogenes in Retail Delicatessens Public Meeting Washington, DC - May 22 nd, 2013

Four-Phase Longitudinal Study Hypotheses L. monocytogenes persists on food and non-food contact surfaces in retail delis Cross-contamination occurs between non- food contact surfaces and food contact surfaces 2 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Four Phase Longitudinal Study - Overview Phase 1: Monthly sampling (prior to operation) for LM and Listeria species in 15 stores (5 stores/state) for 3 months –Also included APC and ATP testing Phase 2: Monthly sampling (during operation) for LM and Listeria species in 30 stores (10 stores/state) for 6 months Phase 3: Develop interventions to be implemented in stores (based on phase 1 and 2 results) Phase 4: Repeat phase 2 with interventions in place Initiated under FSIS/Office of Public Health Science 3 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Results of pre-op sampling (Phase 1) 21/315 samples positive for L. monocytogenes (6.7%) –2/315 samples positive for non-LM Listeria spp. (0.63%) Quantification data indicate that drains and floors can have >10 4 L. monocytogenes/sponge LM pos.Other List. Species pos. Trash cans1/45 (2.2%) Carts2/45 (4.5%)0 Pans1/45 (2.2%)0 Floor next to drain7/45 (15.5%)0 Wall/floor juncture8/45 (17.7%)0 Walk-in cooler & shelving2/45 (4.5%)0 Slicer casing01/45 (2.2%) 4

Phase 1 Pre-Op LM+ by Store - Evidence of L. monocytogenes Persistence 5 AprilMayJune Trash can -7 Cart -47 Pan 10-- Floor Next to Drain 2, 7, 132, 7 Wall/Floor Juncture 2, 5, 72, 72, 7, 10 Walk-in Cooler & Shelving 5, 11-- Slicer Casing --- May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Results – Longitudinal Testing (Phase 2) 30 stores Total samples = % (425/4512) positive for LM –73/1604 (4.5%) of “Food Contact Surfaces” positive for LM –18/540 (3.3%) of “Transfer Points” positive for LM –334/2368 (14.1%) of “Non-Food Contact Surfaces” positive for LM 6 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Food ContactNon-Food Contact Site+/Total%Site+/Total% Slicer Blade5/ Basin Sink Ext6/ Deli Case4/ Floor-Wall Junct. (under 3-basin sink)24/ Case by Meat2/ Basin Sink Exterior7/ Deli Case Tray4/ Floor/Wall Junct (under 1-basin sink)31/ Basin Sink Interior14/1797.8Deli Drain36/ Basin Sink Interior30/ Floor Adjacent to Deli Drain46/ Cold Room Rack4/1802.2Deli Floor23/ Cutting Board4/1522.6Cold Room Floor36/ Rewrap table1/1790.6Cold Room Wall4/ Counter5/1782.8Cold Room Drain40/ Transfer PointStanding Water16/ SiteTotal%Squeegee36/ Slicer Knob3/1801.7Cart Wheel14/ Case Handle8/1804.4Hose6/ Scale Top7/1803.9Trash Can9/ May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Store Month FOOD CONTACT 070/90/81/90/9 0/72/90/90/81/80/90/60/9 080/95/90/90/80/90/70/9 0/83/80/90/100/9 090/9 0/100/90/81/90/9 1/90/9 100/9 0/70/91/90/81/80/9 110/90/100/90/100/90/101/9 0/81/90/91/92/90/9 120/91/90/91/80/90/70/9 0/81/81/90/9 TRANSFER POINT 070/31/30/3 080/32/30/3 1/30/3 090/3 100/31/30/3 110/3 2/30/3 120/3 NON-FOOD CONTACT 070/114/140/14 0/1210/145/140/107/140/150/110/140/12 080/116/140/160/14 0/128/144/140/108/130/140/100/140/110/12 090/116/140/14 1/151/140/107/140/140/110/140/120/13 100/135/150/142/140/140/127/140/140/113/140/140/112/140/100/12 111/115/140/141/140/14 8/141/141/112/140/142/111/141/110/12 120/118/150/141/140/140/128/140/140/113/141/140/112/140/110/12 L. monocytogenes Positive samples: Stores 1-15 by Month 8 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Stores by Month Store Month FOOD CONTACT 08 1/100/91/90/9 1/85/91/102/80/9 5/90/91/90/9 09 0/9 1/90/90/80/93/100/80/9 1/90/9 10 1/100/91/90/9 1/101/91/100/9 0/100/9 11 1/101/90/9 2/90/91/101/80/100/9 0/81/90/9 12 3/100/9 1/90/90/100/90/100/80/9 1/90/9 01 1/90/91/9 0/80/91/90/80/9 1/81/90/9 TRANSFER POINT 08 0/3 3/30/3 2/30/3 09 0/3 1/30/3 10 0/3 11 0/31/30/3 1/30/3 1/30/3 12 1/30/3 01 0/3 1/30/3 NON-FOOD CONTACT 08 4/140/120/140/110/145/145/129/154/121/120/144/119/153/140/ /140/120/140/110/145/140/118/146/110/130/140/129/141/140/ /140/130/141/110/143/130/117/158/130/131/140/129/142/140/ /153/120/140/121/152/140/125/1410/130/152/140/129/150/ /150/120/140/110/144/140/124/157/130/111/140/118/150/ /140/132/140/110/144/140/129/156/120/110/140/119/152/140/14 9 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

30 retail stores – subtyping conclusions 10 12/30 stores show low LM prevalence (≤4 positive samples; <2% prevalence) 4/30 stores show low LM prevalence with a single high prevalence contamination event 14/30 stores show evidence for persistence (preliminary sub-classification) 9 stores show clear evidence for persistence on “non- FCS” area with occasional FCS contamination with persistent type 2 stores show clear evidence for persistence on non FCS area; persistent strain not isolated from FCS 3 stores show possible short term persistence (same subtype isolated in 2 or 3 different months with ≤ 8 total positive samples), two on FCS, one on non-FCS. May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Low LM prevalence with a sporadic high prevalence event AugustSeptemberOctoberNovemberDecemberJanuary Food Contact Sites SlicerCU-258, Deli case Deli case near raw meatNT Deli case traysCU-258, basin sink interior basin sink interiorCU-258, Cold room rack Cutting board Rewrap tableCU-258, CounterCU-258, Non-food contact sites basin sink exteriorCU-258, Floor/wall junction (3-basin) basin sink exteriorCU-258, Floor/wall junction (1-basin)NT - Deli drain Floor adjacent to drainCU-258, Deli floor Cold room floor Cold room wall Cold room drainCU-258, Standing waterNT SqueegeeNT Cart Wheel Hose-NT-- Trash can Transfer Points --- Slicer knob Case handleCU-258, ScaleCU-258,

PFGE data - low prevalence with a high prevalence event SiteSubtype SlicerCU-258,69 Deli case traysCU-258,69 1-basin sink interiorCU-258,69 Rewrap tableCU-258,69 CounterCU-258,69 3-basin sink exterior CU-258,333 1-basin sink exterior CU-258,69 Floor adjacent to drain CU-258,69 Cold room drainCU-258,69 Case handleCU-258,69 ScaleCU-258,69 12 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

30 retail stores – subtyping conclusions 13 12/30 stores show low LM prevalence (≤4 positive samples; <2% prevalence) 4/30 stores show low LM prevalence with a single high prevalence contamination event 14/30 stores show evidence for persistence (preliminary sub-classification) 9 stores show clear evidence for persistence on “non- FCS” area with occasional FCS contamination with persistent type 2 stores show clear evidence for persistence on non FCS area; persistent strain not isolated from FCS 3 stores show possible short term persistence (same subtype isolated in 2 or 3 different months with ≤ 8 total positive samples), two on FCS, one on non-FCS. May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

LM Persistence on non-food contact surfaces with sporadic FCS positive AprilMayJuneJulyAugustSeptemberOctoberNovemberDecember Food Contact Sites Slicer Deli caseNT Deli case near raw meatNT Deli case traysNT basin sink interiorNT CU-57, basin sink interiorNT CU-258,69---CU-294,321- Cold room rack Cutting boardNT -- - Rewrap tableNT CounterNT Non-food contact sites 3-basin sink exteriorNT Floor/wall junction (3-basin)CU-258,69 CU-8,96--CU-258,69 1-basin sink exteriorNT CU-258, Floor/wall junction (1-basin)NT CU-258,69-- Deli drainNT CU-258,69CU-258,333--CU-258,69 Floor adjacent to drain-CU-258,69 - Deli floorNT CU-258, Cold room floorNT CU-258,69CU-295,329-CU-258,69 Cold room wallCU-258, Cold room drainNT CU-258,69 - Standing waterNT -- - SqueegeeNT CU-258,69 - Cart Wheel--CU-258, HoseNT -CU-258, Trash can--CU-258, Transfer Points Slicer knob Case handle ScaleNT May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

LM Persistence on non-food contact surfaces with same type found multiple times on FCS AprilMayJuneJulyAugustSeptemberOctoberNovemberDecember Food Contact Sites Slicer----CU-258, Deli caseNT Deli case near raw meatNT - - Deli case traysNT basin sink interiorNT basin sink interiorNT CU-294,321 CU-57,267 LM Cold room rack Cutting boardNT Rewrap tableNT CounterNT -CU-11, Non-food contact sites 3-basin sink exteriorNT Floor/wall junction (3-basin)--CU-11, basin sink exteriorNT Floor/wall junction (1-basin)NT Deli drainNT CU-11,320 CU-40,96-LM Floor adjacent to drain---CU-11,320 -LM Deli floorNT CU-11, Cold room floorNT CU-11, Cold room wall---CU-11, Cold room drainNT CU-11,320 CU-8,96CU-11,320CU-57,267LM Standing waterNT SqueegeeNT CU-11, Cart Wheel----CU-11, HoseNT Trash can CU-11,320- Transfer Points Slicer knobNT -CU-258, Case handleNT ScaleNT May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Persistence on non-FCS only AprilMayJuneJulyAugustSeptemberOctoberNovemberDecember Food Contact Sites Slicer Deli caseNT Deli case near raw meatNT Deli case traysNT basin sink interiorNT basin sink interiorNT ---CU-40,96CU-200,227- Cold room rack Cutting boardNT Rewrap tableNT CounterNT Non-food contact sites 3-basin sink exteriorNT Floor/wall junction (3- basin)CU-11, basin sink exteriorNT Floor/wall junction (1- basin)NT CU-8, Deli drainNT -CU-8, Floor adjacent to drainCU-8,340---CU-11, Deli floorNT CU-8, Cold room floorNT CU-8, Cold room wall Cold room drainNT Standing waterNT CU-8, SqueegeeNT Cart Wheel---CU-8, HoseNT Trash can Transfer Points Slicer knobNT Case handleNT ScaleNT May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

AugustSeptemberOctoberNovemberDecemberJanuary Food Contact Sites Slicer Deli case Deli case near raw meatNT - Deli case trays---CU-262, basin sink interiorCU-294, basin sink interior---CU-262,79-- Cold room rack Cutting boardNT --- Rewrap table Counter Non-food contact sites 3-basin sink exterior---CU-262,79-- Floor/wall junction (3-basin)-CU-11, basin sink exterior Floor/wall junction (1-basin)CU-294,321CU-11,320-NT-CU-11,320 Deli drain-CU-11, Floor adjacent to drain-CU-263,319--CU-263,318CU-11,320 Deli floorCU-11, Cold room floorCU-11,320- CU-263,319-CU-11,320 Cold room wall Cold room drainCU-11,320 -NT- Standing waterNT CU-11,320NT Squeegee--CU-11,320- Cart Wheel Hose--NT--- Trash canCU-11, Transfer Points Slicer knob Case handle---CU-262,79-- Scale Persistence on non-FCS & possible short term persistence of 2 nd subtype on FCS 17

Quantitative data 18 Occasional high numbers on non-food contact surfaces Floor next to deli drain Pre-op: 4x10 4, 3x10 2, and 2.5x10 5 /sponge (total of 3 stores) During operation: <10; 1x10 5 /sponge (2 stores) Cold room floor or drain During operation: 5x10 6, 1x10 6, 3x10 1 /sponge (3 stores) May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

L. monocytogenes and Listeria spp. testing 19 Among a total of 4,512 samples: 3,980 (88.2%) samples negative for both LM and Listeria spp. 291 (6.4%) samples positive for LM only 133 (2.9%) samples positive for LM and Listeria spp. 108 (2.4%) samples positive for Listeria spp. Only Data indicate that L. monocytogenes testing will facilitate focus on actual food safety hazard Some stores show presence of indictor, but not the pathogen May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Summary and conclusions L. monocytogenes contamination in retail environments non-food contact surfaces is not uncommon –L. monocytogenes is common in surrounding environments –L. monocytogenes contamination of FCS is considerably less than contamination of non-FCS –Wide variation in L. monocytogenes prevalence among stores L. monocytogenes persist widely in retail environments (>35%) –Need to control niches Focus on L. monocytogenes testing rather than Listeria spp. testing is warranted at retail 20 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting

Acknowledgments Students and staff: S. Roof, S. Warchocki, E. Fortes, E. Wright, C. Simmons, B. Ziegler, S. Chambers, E. Christian, P. Cook, J. Wang, C. Wickware, A. Pleitner, N. Donovan, N. Boyd, J. Eichinger, L. Hill, J. Wang, S. Hammons Collaborators: Retailers, New York State Department of Agriculture and Markets, Neogen Corp., Ecolab Financial support: u USDA, Food Safety and Inspection Service/Office of Public Health Science u Food Marketing Institute Foundation u American Meat Institute Foundation 21 May 22 nd, 2013 Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens Public Meeting