TABLE 2.
Mutations in the QRDR of and CIP and LVX MICs for 30 NTHi clinical isolates resistant to NAL
| Isolate(s)a | Disk diffusion inhibitory zone diam (mm) |
MIC (μg/ml) |
Mutation(s) in QRDRb |
||||
|---|---|---|---|---|---|---|---|
| NAL | CIP | CIP | LVX | GyrA | ParC | ParE | |
| 13.1 | 12 | 28 | 0.12 | 0.12 | Ser84Leu | — | — |
| 17.1 | 10 | 26 | 0.5 | 0.5 | Ser84Leu | — | — |
| 15.1, 23.1 | 6 | 24 | 0.5 | 0.5 | Ser84Leu | Ser84Ile | — |
| 1.1 | 9 | 20 | 0.5 | 0.5 | Ser84Tyr | Glu88Lys | — |
| 21.1 | 6 | 22 | 1 | 0.5 | Ser84Leu | Ser84Ile | — |
| 6.1 | 10 | 20 | 1 | 0.5 | Ser84Leu | Ser84Ile | — |
| 3.1 | 6 | 20 | 1 | 1 | Ser84Leu | Glu88Lys | — |
| 12.1 | 6 | 20 | 2 | 1 | Ser84Leu | Glu88Lys | — |
| 5.1 | 10 | 16 | 2 | 1 | Asp88Tyr | Glu88Lys | — |
| 2.1–2.5 | 6 | 20 | 2 | 1 | Ser84Tyr, Asp88Tyr | Asp83Gly, Ser84Ala | — |
| 11.1 | 6 | 15 | 8 | 4 | Ser84Tyr, Asp88Tyr | Ser84Asn | — |
| 7.1 | 6 | 6 | 8 | 4 | Ser84Leu, Asp88Tyr | Glu88Lys | — |
| 10.1, 10.2, 14.1 | 6 | 6 | 16 | 16 | Ser84Leu, Asp88Tyr | Glu88Lys | — |
| 8.1 | 6 | 6 | 16 | 16 | Ser84Leu, Asp88Asn | Gly82Asp | — |
| 19.1 | 6 | 6 | 16 | 16 | Ser84Leu, Asp88Asn | Ser84Arg | — |
| 16.1 | 6 | 6 | 16 | 8 | Ser84Tyr, Asp88Gly | Ser84Ile | Asp420Asn |
| 18.1 | 6 | 6 | 16 | 16 | Ser84Tyr, Asp88Gly | Ser84Ile | Asp420Asn |
| 24.1 | 6 | 6 | 16 | 16 | Ser84Leu, Asp88Gly | Ser84Ile | Asp420Asn |
| 20.1, 20.2, 22.1 | 6 | 6 | 16 | 16 | Ser84Leu, Asp88Asn | Ser84Ile | Asp420Asn |
| 4.1 | 6 | 6 | 16 | 16 | Ser84Leu, Asp88Tyr | Gly82Cys, Glu88Lys | — |
| 9.1 | 6 | 6 | 16 | 16 | Ser84Tyr, Asp88Tyr | Ser84Ile, Glu88Lys | — |
a
Isolates are numbered accord to their origins of isolation as defined in Table 1.
b
Changes at positions classically involved in resistance are shown in bold. Additional amino acid changes, found also in susceptible isolates, were ParC S133A (six isolates), ParC N138S (eight isolates), ParE R368H and S458L (one isolate), and GyrB A400V (three isolates). No amino acid changes have been detected in GyrB. —, no changes.