Article Figures & Data
Figures
- Fig. 1.
Various forms of DDST for two representative isolates ofE. cloacae (TSV-287 and TSV-9) producing β-lactamases of pI 8.2 (A) and 6.9 (B), respectively. A1 and B1, tests with application of the cephalosporin disks at a standard distance of 30 mm from the clavulanate-containing disk (center to center); A2 and B2, tests with proximal application of the disks at 20 mm. AMC, amoxicillin-clavulanate; CAZ, ceftazidime; CTX, cefotaxime; CRO, ceftriaxone; FEP, cefepime; CPO, cefpirome.
Tables
- Table 1.
MICs of selected β-lactams and β-lactamase contents for representative enterobacters and E. coli transconjugants
Strain β-Lactamase pI(s)a Etest MIC (μg/ml)b Amx Amc Tic TLc Pip PTz Fox Caz Ctx Cro Atm Fep Cpo Caz-resistant group E. cloacaeTSV-9 (8.0) + 6.9 >256 96 >256 128 128 16 256 >256 8 12 8 0.75 8 trccTSV-9 (8.5) + 6.9 >256 8 >256 32 32 1.5 3 >256 2 4 4 0.38 4 E. cloacaeTSV-213d (8.0) + 6.9 >256 128 >256 256 48 1.5 256 192 4 6 3 0.38 6 ESC-resistant group E. cloacaeTSV-43 (8.0) + 6.9 + 5.4 >256 192 >256 192 128 16 192 >256 12 32 16 1.5 16 trc TSV-43 (8.5) + 6.9 >256 12 >256 64 64 1.5 2 >256 2 3 4 0.25 3 E. cloacaeTSV-287 (8.0) + 8.2 >256 192 >256 128 >256 64 192 >256 128 192 >256 6 16 trc TSV-287 (8.5) + 8.2 >256 6 >256 4 128 12 2 48 4 1.5 24 0.25 0.75 E. aerogenesTSV-89 (8.3) + 8.2 >256 12 >256 >256 >256 32 >256 >256 24 64 >256 2 8 trc TSV-89 (8.5) + 8.2 >256 8 >256 6 128 16 3 64 6 2 32 0.5 1.5 E. cloacaeTSV-144e (8.0) + 5.4 >256 192 >256 128 192 64 >256 32 32 32 16 0.38 2 trc TSV-144 (8.5) + 5.4 >256 8 >256 6 128 8 2 0.19 0.047 0.064 0.094 0.047 0.5 E. cloacaeTSV-68 (9.0) >256 192 >256 >256 >256 >256 >256 128 >256 >256 96 8 24 E. aerogenesTSV-272 (8.3) 128 16 256 192 128 64 >256 64 24 >32 8 0.75 4 ESC-susceptible group E. cloacaeTSV-323f (8.0) 256 32 6 4 2 2 96 0.5 0.125 0.125 0.064 0.032 0.094 E. cloacaeTSV-123e (9.2) 96 12 4 3 4 3 >256 0.38 0.125 0.125 0.094 0.032 0.094 E. aerogenesTSV-92 (8.3) 128 12 2 3 4 3 >256 0.5 0.19 0.19 0.125 0.064 0.064 E. coli 1R716 (recipient) (8.5) 3 3 1 1.5 1 1 4 0.25 0.064 0.064 0.125 0.032 0.047 ↵a pIs in parentheses refer to those of β-lactamases considered chromosomal. Boldface numbers indicate pIs of ESBLs.
↵b Abbreviations: Amx, amoxicillin; Amc, amoxicillin-clavulanate; Tic, ticarcillin; TLc, ticarcillin-clavulanate; Pip, piperacillin; PTz, piperacillin-tazobactam; Fox, cefoxitin; Caz, ceftazidime; Ctx, cefotaxime; Cro, ceftriaxone; Atm, aztreonam; Fep, cefepime; Cpo, cefpirome.
↵c trc, transconjugated.
↵d Strains with true-positive Vitek ESBL detection test results.
↵e Two of three strains had false-positive DDST results.
↵f Strains with false-positive Vitek ESBL detection test results.
- Table 2.
Comparative evaluation of the Vitek ESBL detection test and the various forms of DDSTs applied for screening of ESBLs among 56E. cloacae and 12 E. aerogenes isolates
ESBL screening method No (%) of positive tests among confirmed ESBL producers No (%) of positive tests among non-ESBL producers E. cloacae (n = 24) E. aerogenes (n = 7) All isolates (n = 31) E. cloacae (n = 32) E. aerogenes(n = 5) All isolates (n = 37) Vitek ESBL test 2 (8.3) 0 2 (6.4) 1 (3.1) 0 1 (2.7) DDSTs Amc, 30 mm from Caz 0 0 0 1 0 1 (2.7) Ctx 0 2 2 0 0 0 Cro 2 1 1 0 0 0 Atm 2 0 2 1 0 1 At least one combination 3 (12.5) 2 (28.6) 5 (16.1) 1 (3.1) 0 1 (2.7) Amc, 20 mm from Caz 7 2 9 0 0 0 Ctx 8 4 12 0 0 0 Cro 8 4 12 0 0 0 Atm 17 4 21 0 0 0 At least one combination 17 (70.8) 5 (71.4) 22 (71) 0 0 0 Amc, 30 mm from Cpo 7 4 11 3 0 3 Fep 13 6 19 2 0 2 At least one combination 13 (54.2) 6 (85.7) 19 (61.3) 3 (9.4) 0 3 (8.1) Amc, 20 mm from Cpo 18 6 24 1 0 1 Fep 22 6 28 0 0 0 At least one combination 22 (91.7) 6 (85.7) 28 (90.3) 1 (3.1) 0 1 (2.7) At least one DDST 24 (100) 6 (85.7) 30 (96.8) 3 (9.4) 0 3 (8.1)
