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. 2017 Dec 26;40(6):317–328. doi: 10.1016/j.bj.2017.09.001

Table 2.

Discordant results: False positives and false negatives.

Sample type Media Number Comments
False positives
Urines CHROM 3
  • •

    Dust or agar artefacts wrongly considered as microbial objects by the algorithm

  • •

    False negative reported by the technician

See Figs. D.1–F.1
Urines COL 3
Urines MAC 5
Isolates CHROM 3
Isolates COL 1
Total 15
False negatives
Urines CHROM 8 Plates containing between 1 and 3 colonies were not detected by the algorithms (see Figs. G.1 and H.1).
  • •

    Colonies considered as non microbial objects (dust, artifacts, …)

  • •

    Colonies located on the edges of the plate, which is a zone not included in image analysis

  • •

    Colonies not detected
Urines COL 1
Isolates CHROM 29 Some plates containing Lactobacillus fermentum (8), Candida albicans (6),Corynebacterium striatum (5), Micrococcus luteus (2), Streptococcus mitis group (2), Staphylococcus saprophyticus (2), Staphylococcus haemolyticus (1), Staphylococcus epidermidis (1), Aerococcus urinae (1) and Pseudomonas aeruginosa (1) were not detected by the algorithms (see Fig. G.1).
  • •

    The growth of some bacterial species on CHROM agar produced lawns of tiny faint colonies after 24 h incubation in normal atmosphere that were not detected by the algorithm (see Fig. G.1, C. striatum, L. fermentum)

  • •

    Colonies considered as non microbial objects (dust, artifacts, …).

  • •

    Colonies located on the edges of the plate, which is a zone not included in image analysis (ex Fig. G.1,#16)

  • •

    Colonies not detected

  • •

    Possible false positive reported by the technician (see Fig. G.1,#23/27/28/38/42)
Isolates COL 7 Some plates containing between 1 to 4 colonies of Candida albicans (5), Streptococcus mitis group (1) and Pseudomonas aeruginosa (1) were not detected by the algorithms (see Fig. H.1).
  • •

    Colonies considered as non microbial objects (dust, artifacts, …)

  • •

    Colonies located on the edges of the plate, which is a zone not included in image analysis

  • •

    Colonies not detected
Isolates MAC 1 A plate containing one colony of Pseudomonas aeruginosa was not detected by the algorithm. The colony was located on the edge of the plate, which is a zone not included in image analysis (see Fig. I.1).
Total 46