TABLE 1.
Performance of the Check KPC/ESBL microarray assay in identification of β-lactamase genesa
| Species |
blaKPC |
blaSHV |
blaTEM |
blaCTX-M |
Isolates with all bla genes correctly reported |
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No. of isolates positive by PCR/Seq | Agreementi (%) | ESBLd |
Non-ESBL |
Total |
ESBLd |
Non-ESBL |
Total |
No. of isolates positive by PCR/Seq | Agreementi (%) | Agreementi (%) | |||||||
| No. of isolates positive by PCR/Seq | Agreementi (%) | No. of isolates positive by PCR/Seqc | Agreementi (%) | No. of isolates positive by PCR/Seq | Agreementi (%) | No. of isolates positive by PCR/Seq | Agreementi (%) | No. of isolates positive by PCR/Seqe | Agreementi (%) | No. of isolates positive by PCR/Seq | Agreementi (%) | ||||||
| K. pneumoniae (n = 79)b | 52 | 79/79 (100) | 41 | 41/41 (100) | 38 | 31/38 (81.6) | 79 | 72/79 (91.1) | 3 | 3/3 (100) | 64 | 64/64 (100) | 67 | 79/79 (100) | 8 | 79/79 (100) | 72/79 (91.1) |
| E. coli (n = 22)b | 4 | 22/22 (100) | 3 | 2/3 (66.7) | 2 | 2/2 (100) | 5 | 21/22 (95.5) | 2 | 2/2 (100) | 7 | 7/7 (100) | 9 | 21/22 (95.5) | 9 | 22/22 (100) | 20/22 (90.9) |
| A. baumannii (n = 4) | 0 | 4/4 (100) | 0 | 0 | 0 | 4/4 (100) | 2 | 2/2 (100) | 2 | 4/4 (100) | 2 | 4/4 (100) | 4/4 (100) | ||||
| Enterobacter cloacae (n = 1) | 1 | 1/1 (100) | 0 | 0 | 0 | 1/1 (100) | 0 | 1 | 1/1 (100) | 1 | 1/1 (100) | 0 | 1/1 (100) | 1/1 (100) | |||
| Total (n = 106) | 57 | 106/106 (100)f | 44 | 43/44 (97.7) | 40 | 33/40 (82.5) | 84 | 98/106 (92.5)g | 7 | 7/7 (100) | 72 | 72/72 (100) | 79 | 105/106 (99.1)h | 19 | 106/106 (100)f | 97/106 (91.5) |
Results represent comparisons of the Check KPC/ESBL microarray assay to PCR amplification followed by DNA sequencing (PCR/Seq).
Includes control isolates.
One E. coli isolate containing blaSHV-38 was reported as a non-ESBL SHV type; six K. pneumoniae isolates containing a blaSHV-non-ESBL gene (i.e., a blaSHV-1 or blaSHV-11 gene) were reported as representing SHV-ESBL strains; one K. pneumoniae isolate containing blaSHV-11 was reported as SHV negative (see Table S1 in the supplemental material).
Includes isolates containing blaESBL (e.g., blaSHV-12) or blaESBL plus blanon-ESBL genes (e.g., blaSHV-12 and blaSHV-11).
One blaTEM-negative E. coli isolate was reported as a non-ESBL TEM strain.
Sensitivity, 100%; specificity, 100%; positive predictive value, 100%; negative predictive value, 100%.
Sensitivity, 98.8%; specificity, 100%; positive predictive value, 100%; negative predictive value, 95.7%.
Sensitivity, 100%; specificity, 96.4%; positive predictive value, 98.8%; negative predictive value, 100%.
The value preceding the slash is the number of isolates whose Check KPC/ESBL microarray results agreed with their PCR/Seq results, and the value following the slash is the total number of isolates tested by both assays.