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Table. 3.

Table. 3.

Categorical agreement between fluconazole susceptibility results determined by DDT using two inocula and the BMD method after each incubation time for the readable Candida isolates*

Species (N tested) Incubation time (hr) DDT using a standard inoculum (McFarland 0.5) DDT using a large inoculum (McFarland 2.5)


Readable N (%) % CA N (%) of isolates with discrepancies Readable N (%) % CA N (%) of isolates with discrepancies


VME ME Minor VME ME Minor
C. albicans
(66)
10 5 (7.6) 100.0 0 0 0 26 (39.4) 100.0 0 0 0
12 38 (57.6) 100.0 0 0 0 55 (83.3) 96.4 1 (1.8) 0 1 (1.8)
14 63 (95.5) 96.8 2 (3.2) 0 0 63 (95.5) 96.8 1 (1.6) 0 1 (1.6)
16 63 (95.5) 95.2 2 (3.2) 0 1 (1.6) 66 (100.0) 95.5 1 (1.5) 0 2 (3.0)
18 63 (95.5) 95.2 2 (3.2) 0 1 (1.6) 66 (100.0) 95.5 2 (3.0) 0 1 (1.5)
20 64 (97.0) 96.9 2 (3.1) 0 0 66 (100.0) 95.5 1 (1.5) 0 2 (3.0)
22 66 (100.0) 97.0 2 (3.0) 0 0 66 (100.0) 97.0 1 (1.5) 0 1 (1.5)
24 66 (100.0) 97.0 2 (3.0) 0 0 66 (100.0) 97.0 1 (1.5) 0 1 (1.5)
C. glabrata
(69)
10 46 (66.7) 100.0 0 0 0 60 (87.0) 100.0 0 0 0
12 60 (87.0) 100.0 0 0 0 68 (98.6) 98.5 0 0 1 (1.5)
14 67 (97.1) 98.5 0 0 1 (1.5) 69 (100.0) 98.6 0 0 1 (1.4)
16 69 (100.0) 98.6 0 0 1 (1.4) 69 (100.0) 98.6 0 0 1 (1.4)
18 69 (100.0) 98.6 0 0 1 (1.4) 69 (100.0) 98.6 0 0 1 (1.4)
20 69 (100.0) 98.6 0 0 1 (1.4) 69 (100.0) 98.6 0 0 1 (1.4)
22 69 (100.0) 98.6 0 0 1 (1.4) 69 (100.0) 97.1 0 0 2 (2.9)
24 69 (100.0) 98.6 0 0 1 (1.4) 69 (100.0) 94.2 0 0 4 (5.8)
C. parapsilosis
(29)
10 0 (0.0) - 0 0 0 2 (6.9) 100.0 0 0 0
12 1 (3.4) 100.0 0 0 0 24 (82.8) 95.8 0 0 1 (4.2)
14 19 (65.5) 68.4 1 (5.3) 0 5 (26.3) 26 (89.7) 92.3 0 0 2 (7.7)
16 22 (75.9) 90.9 0 0 2 (9.1) 29 (100.0) 93.1 0 0 2 (6.9)
18 25 (86.2) 92.0 0 0 2 (8.0) 29 (100.0) 93.1 0 0 2 (6.9)
20 29 (100.0) 89.7 2 (6.9) 0 1 (3.4) 29 (100.0) 93.1 0 0 2 (6.9)
22 29 (100.0) 89.7 2 (6.9) 0 1 (3.4) 29 (100.0) 93.1 0 0 2 (6.9)
24 29 (100.0) 89.7 1 (3.4) 0 2 (6.9) 29 (100.0) 96.6 0 0 1 (3.4)
C. tropicalis
(24)
10 15 (62.5) 93.3 0 0 1 (6.7) 22 (91.7) 95.5 1 (4.5) 0 0
12 21 (87.5) 90.5 1 (4.8) 0 1 (4.8) 24 (100.0) 87.5 1 (4.2) 0 2 (8.3)
14 24 (100.0) 91.7 1 (4.2) 0 1 (4.2) 24 (100.0) 91.7 1 (4.2) 0 1 (4.2)
16 24 (100.0) 91.7 1 (4.2) 0 1 (4.2) 24 (100.0) 95.8 1 (4.2) 0 0
18 24 (100.0) 95.8 1 (4.2) 0 0 24 (100.0) 95.8 1 (4.2) 0 0
20 24 (100.0) 95.8 0 0 1 (4.2) 24 (100.0) 95.8 1 (4.2) 0 0
22 24 (100.0) 95.8 0 0 1 (4.2) 24 (100.0) 95.8 0 0 1 (4.2)
24 24 (100.0) 95.8 0 0 1 (4.2) 24 (100.0) 95.8 0 0 1 (4.2)
Total (188) 10 66 (35.1) 98.5 0 0 1 (1.5) 110 (58.5) 99.1 1 (0.9) 0 0
12 120 (63.8) 98.3 1 (0.8) 0 1 (0.8) 171 (91.0) 95.9 2 (1.2) 0 5 (2.9)
14 173 (92.0) 93.6 4 (2.3) 0 7 (4.0) 182 (96.8) 96.2 2 (1.1) 0 5 (2.7)
16 178 (94.7) 95.5 3 (1.7) 0 5 (2.8) 188 (100.0) 96.3 2 (1.1) 0 5 (2.7)
18 181 (96.3) 96.1 3 (1.7) 0 4 (2.2) 188 (100.0) 96.3 3 (1.6) 0 4 (2.1)
20 186 (98.9) 96.2 4 (2.2) 0 3 (1.6) 188 (100.0) 96.3 2 (1.1) 0 5 (2.7)
22 188 (100.0) 96.3 4 (2.1) 0 3 (1.6) 188 (100.0) 96.3 1 (0.5) 0 6 (3.2)
24 188 (100.0) 96.3 3 (1.6) 0 4 (2.1) 188 (100.0) 95.7 1 (0.5) 0 7 (3.7)

*BMD method was conducted strictly according to CLSI M27-ED4 document (24-hour incubation), but DDT was modified with the use of two cell suspensions (McFarland 0.5, standard inoculum; and 2.5, large inoculum), and inhibition zones were read at 2-hour intervals from 10 hours to 24 hours [15]. P<0.05, significant difference between the standard and large inoculums within a given category (i.e., readable N; % CA) and a given Candida species.

Abbreviations: BMD, broth microdilution; CA, categorical agreement; DDT, disk diffusion testing; ME, major error; Minor, minor error; VME, very major error.

Ann Lab Med 2021;41:559~567

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