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Table 1 MPN-based quantification of L. monocytogenes in samples collected from three tree fruit packing facilities at two time points in March 2018

From: The occurrence of Listeria monocytogenes is associated with built environment microbiota in three tree fruit processing facilities

Log MPN/sponge sample Facility F1c Facility F2 Facility F3c
Wash Dry Wax Wash Dry Wax Wash Dry Wax
Trial 1a < LD < LD < LD 3.87 5.02 4.38 LD < 1.55d < LD LD < 1.55d
Trial 2b < LD < LD < LD 3.15 3.32 5.35 1.55 1.55 2.63
Average < LD < LD < LD 3.51 4.17 4.87 < 1.55 0.82 < 2.63
  1. aFour dilutions (10−2, 10−3, 10−4, 10−5) were used in the MPN calculation. Each dilution was tested in triplicates. Sample homogenate (a sponge in 90 ml of BLEB) was also enriched
  2. bFive dilutions (10−2, 10−3, 10−4, 10−5, 10−6) were used in MPN calculation. Each dilution was tested in triplicates. Sample homogenate (a sponge in 90 ml of BLEB) was also enriched
  3. c< LD indicates that L. monocytogenes was below the limit of detection, which was at least one viable cell per sample, grown to at least 105 cells/ml by the time the enrichment was completed
  4. dThe level of L. monocytogenes was between the limit of detection and 1.55 log10 MPN/sponge sample. L. monocytogenes was detected in enriched sponge homogenate; however, none of the MPN dilution tubes were positive