TABLE 1.
Distribution of resistance targets identified by CT103 and CT103 XL according to species
| Species (no. of isolates)a | Resistance gene target | No. of resistance gene variants |
||||||
|---|---|---|---|---|---|---|---|---|
| Total no. of targetsb | Detected by CT103 | Additionally detected by CT103c | Missed by CT103 (false negative) | Detected by CT103 XL | Additionally detected by CT103 XLc | Missed by CT103 XL (false negative) | ||
| Escherichia coli (93) | CTX-M-1 groupd | 36 | 36 | 2e | 0 | 36 | 2e | 0 |
| CTX-M-9 groupd | 19 | 17 | 3 | 2e | 18 | 3 | 1e | |
| SHVf | 19 | 18 | 5 | 1g | 18 | 5 | 1g | |
| TEMh | 58 | 57 | 29 | 1i | 53 | 29 | 5i | |
| Plasmid-borne AmpCj | 13 | 13 | 3 | 0 | 12k | 3 | 0k | |
| VEB | 1 | NAl | NA | NA | 1 | 0 | 0 | |
| NDM | 1 | 1 | 0 | 0 | 1 | 0 | 0 | |
| KPC | 1 | 1 | 0 | 0 | 1 | 0 | 0 | |
| Klebsiella pneumoniae complex (8) | TEMm | 3 | 3 | 1 | 0 | 3 | 1 | 0 |
| SHVn | 8 | 8 | 1 | 0 | 6o | 1 | 0o | |
| CTX-M-1 groupp | 1 | 1 | 0 | 0 | 1 | 0 | 0 | |
| Citrobacter koseri (1) | TEMq | 1 | 1 | 1 | 0 | 1 | 1 | 0 |
| KPC | 1 | 1 | 0 | 0 | 1 | 0 | 0 | |
| Enterobacter aerogenes (1) | KPC | 1 | 1 | 0 | 0 | 1 | 0 | 0 |
| SHVg | 1 | 0 | 0 | 1 | 1 | 1 | 0 | |
| TEMq | 1 | 0 | 0 | 1 | 1 | 1 | 0 | |
| Enterobacter cloacae complex (1) | KPC | 1 | 1 | 0 | 0 | 1 | 0 | 0 |
| Proteus mirabilis (1) | KPC | 1 | 1 | 0 | 0 | 1 | 0 | 0 |
| Providencia stuartii (1) | KPC | 1 | 1 | 0 | 0 | 1 | 0 | 0 |
| Serratia marcescens (1) | TEMq | 1 | 1 | 1 | 0 | 1 | 1 | 0 |
| KPC | 1 | 1 | 0 | 0 | 1 | 0 | 0 | |
| Pseudomonas aeruginosa (1) | VIM | 1 | 1 | 0 | 0 | 1 | 0 | 0 |
Includes negative controls comprising 2 E. coli isolates, which lost plasmids carrying blaSHV or blaKPC during cryopreservation. These two isolates were found, based on the studies performed herein, to harbor blaCTX-M-9/blaTEM and blaCTX-M-9.
As previously characterized, as part of reference collections and also if detected as present by the CT103 or CT103 XL assay, and confirmed by conventional PCR.
Resistance target was not previously known to be present but was identified by the CT103 or CT103 XL assays and confirmed by conventional PCR.
The CTX-M-1 group comprises (no. of isolates) CTX-M-1 (2), CTX-M-1 like (1), CTX-M-3 like (4), CTX-M-15 (26), CTX-M-22 (1), CTX-M-27 (1), and CTX-M-28 (1); The CTX-M-9 group comprises (no. of isolates) CTX-M-9 (1), CTX-M-14 (14), CTX-M-27(1), and CTX-M-9 (unspecified) (3).
CT103 and CT103 XL detected a CTX-M-1 target in a reference CTX-M-14 isolate, which is part of the CTX-M-9 group, but did not detect CTX-M-9. Conventional PCR confirmed the presence of CTX-M-1 and CTX-M-9. In addition, CT103 missed a CTX-M-27 (CTX-M-9 group).
The SHV group comprises (no. of isolates) SHV-1 (1), SHV-12 (4), and SHV (unspecified) (14).
SHV (unspecified).
The TEM group comprises (no. of isolates) TEM-1 (4), TEM-1a (7), TEM-1c (2), TEM-1d (1), TEM-6 (1), TEM-10 (1), TEM-12 (1), TEM-26b (2), TEM-43 (1), TEM-104 (1), and TEM (unspecified) (37).
One TEM (unspecified) was missed by CT103, and two TEM-1a, one TEM-1d, one TEM-6, and one TEM (unspecified) was missed by CT103 XL.
Plasmid-borne AmpC comprises (no. of isolates) CMY-2 (11), CMY-8 (1), and FOX-5 (1).
One nonviable isolate was not tested.
NA, not available.
The TEM group comprises (no. of isolates) TEM-1 (1), TEM-1/TEM-10 cocarried (1), and TEM (unspecified) (1).
The SHV group comprises (no. of isolates) SHV-5/55 (4), SHV-12 (1), and SHV (unspecified) (3).
Two nonviable isolates were not tested.
One CTX-M-12 isolate.
TEM (unspecified).